2014Rosov pinSECOND REGIONAL ROUNDTABLE: REFRACTORY, PROCESS INDUSTRY AND NANOTECHNOLOGY

Programme andThe Book of Abstracts

Rosov pin 2014

SECOND REGIONALROUND TABLE:

CENTER FOR INDUSTRIAL AND TECHNOLOGICAL DEVELOPMENT ”ANDREVLJE”, FRUŠKA GORA, SERBIA, OCTOBER 23-24, 2014

Organised by:> Vinča Institute of Nuclear Sciences, Belgrade> Engineering Academy of Serbia, Belgrade> Lafarge BFC d.o.o. Beočin > REAL S d.o.o. Beograd

“ROSOV PIN 2014 focuses on connecting different types of nanotechnology with conventional technologies in refractory and process industry. Nanotechnologies are not only present in modern high tech technology, but also in conventional technology applied in the process industry and refractory, giving the materials a completely new mechanical and corrosion properties.”

CENTER FOR INDUSTRIAL AND TECHNOLOGICAL DEVELOPMENT ”ANDREVLJE”, FRUŠKA GORA, SERBIA, OCTOBER 23-24, 2014

REFRACTORY, PROCESS INDUSTRY AND NANOTECHNOLOGY

ENGENEERING ACADEMYOF SERBIA VINČA INSTITUTE

OF NUCLEAR SCIENCES

 

Second regional roundtable: Refractory, process industry and nanotechnology

ROSOV PIN 2014

Center for Industrial and Technological development ”Andrevlje”, Fruška Gora, Serbia, October 23-24, 2014

 

 

 

 

 

 

 

Programme and

The Book of Abstracts

Organised by: Vinča Institute of Nuclear Sciences, Belgrade

Engineering Academy of Serbia, Belgrade Lafarge BFC d.o.o. Beočin

REAL S d.o.o. Beograd

 

Title: Second regional roundtable: Refractory, process industry and nanotechnology ROSOV PIN 2014 Programme and The Book of Abstracts

Publishers: Vinča Institute of Nuclear Sciences, Belgrade, Serbia Engineering Academy of Serbia, Belgrade, Serbia Editor: Vukoman Jokanović Technical editor: Božana Čolović Sponsors: LAFARGE BFC d.o.o. Beočin REAL S d.o.o. Beograd GALAX d.o.o. Donji Žabar, RS, BiH BOMEX Invest d.o.o. Beograd Printed in: MP štampa, Novi Sad Circulation: 100 copies ISBN: 978-86-7306-125-2 Acknowledgement: The Organizing and Scientific comities of ROSOV PIN 2014 are grateful to the Ministry of Education, Science and Technological Development of the Republic of Serbia for financial support.

 

Dear colleagues,

We are pleased to welcome you in the center “Andrevlje”, placed in the hearth of beautiful mountain Fruška Gora, at the Second regional roundtable “Refractory, process industry and nanotechnology”, ROSOV PIN 2014.

ROSOV PIN 2014 focuses on connecting different types of nanotechnology with conventional technologies in refractory and process industry. Nanotechnologies are not only present in modern high tech technology, but also in conventional technology applied in the process industry and refractory, giving the materials a completely new mechanical and corrosion properties.

The roundtable is organized in three different parts: Refractory, including the preparation of mineral raw materials; Process technology, including the cement industry, glass industry, iron and steel and non-ferrous metallurgy; and Nanotechnology, which covers the general principles of nanotechnology and its place in the development of advanced refractories and ceramics in general, powder metallurgy and carbon materials.

The desired intention of the organizers is to collect as many corporate actors, including producers, consumers and providers of services in the field of refractory and process industry in particular, and to open innovative ways of the penetration of new technologies based on nanotechnology in various types of process industry, in order to create entirely new products and to accelerate technological progress in industries that are mostly present in our region. Completely new approaches and technological concepts are welcome.

Have a nice time and a fruitful discussion with your colleagues from scientific institutions and experts from the industry. We hope that you will establish new connections which will lead to further efficient collaboration.

On behalf of the Organizing and Scientific Committee

Vukoman Jokanović

 

Scientific committee

Vukoman Jokanović, Vinča Institute of Nuclear Sciences, Belgrade, Serbia

Zlatko Rakočević, Vinča Institute of Nuclear Sciences, Belgrade, Serbia

Branko Nikolić, Engineering Academy of Serbia, Belgrade, Serbia

Mirko Gojić, Faculty of Metallurgy, Department for Physical metallurgy, Sisak, Croatia

Maja Dotour-Sikirić, Ruđer Bošković Institute, Zagreb, Croatia

Vesna Babić-Ivančić, Ruđer Bošković Institute, Zagreb, Croatia

Rebeka Rudolf, Faculty of Mechanical Engineering, Maribor, Slovenia

Ilija Nasov, Institute of Physics, St. Cyril and Methodius University, Skopje, Macedonia

Mira Vukčević, Faculty of Metallurgy and Technology, Podgorica, Monte Negro

Monika Jenko, Institute of Metals and Technology, Ljubljana, Slovenia

Tatjana Volkov Husović, Faculty of Technology and Metallurgy, Belgrade, Serbia

Branko Bugarski, Faculty of Technology and Metallurgy, Belgrade, Serbia

Ljubiša Andrić, Institute for Technology of Nuclear and Other Mineral Raw Materials, Belgrade, Serbia

Amir Baraković, Faculty of Mining, Geology and Civil Engineering, Tuzla, Bosnia and Herzegovina

Željko Kamberović, Faculty of Technology and Metallurgy, Belgrade, Serbia

Dejan Marković, Faculty of Dentistry, Belgrade, Serbia

Slavoljub Živković, Faculty of Dentistry, Belgrade, Serbia

Nikola Bajić, Institute for Chemical Power Sources, Belgrade, Serbia

Nenad Radić, Institute of Chemistry, Technology and Metallurgy, Belgrade, Serbia

Duško Borka, Vinča Institute of Nuclear Sciences, Belgrade, Serbia

Dušan Milivojević, Vinča Institute of Nuclear Sciences, Belgrade, Serbia

Anka Trajkovska Petkoska, University St. Kliment Ohridski, Bitola, R. Macedonia

 

Organizing Committee

Goran Lazić, LAFARGE BFC d.o.o., Beočin, Serbia

Vukoman Jokanović, Vinča Institute of Nuclear Sciences, Belgrade, Serbia

Snežana Pašalić, Ministry of Education, Science and Technological Development of the Republic of Serbia

Branko Nikolić, Engineering Academy of Serbia, Belgrade, Serbia

Vesna Babić-Ivančić, Ruđer Bošković Institute, Zagreb, Croatia

Božana Čolović, Vinča Institute of Nuclear Sciences, Belgrade, Serbia

Milan Petrović, Faculty of Dentistry, Belgrade, Serbia

Svetlana Nikolić, Faculty of Technology and Metallurgy, Belgrade, Serbia

Miodrag Stević, Real S d.o.o., Belgrade, Serbia

Svetolik Baucal, Lafarge BFC d.o.o., Beočin, Serbia

Ivan Kranjčić, Zagorka, Bedekovčina, Croatia

Marko Jokanović, Tehnoimpex, Belgrade, Serbia

Nedret Kikanović, Regional Chamber of Commerce, Tuzla, Bosnia and Herzegovina

Gorica Avramović, Bomex, Belgrade, Serbia

Gordana Višnar, VIGO, Jesenice, Slovenia

Jelena Stamenkovski, Holcim (Srbija), Popovac, Serbia

Toše Dimitrievski, Vatrostalna, Skoplje, Macedonia

Momčilo Tadić, VGI-Rivir, Nikšić, Monte Negro

Dalibor Stević, Real S d.o.o., Belgrade, Serbia

 

Programme

 

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General conference program Thursday, October 23th 2014

0800-0900 Registration

0900-0930 Opening ceremony

0930-1115 Plenary lectures

1115-1135 Coffee break

1135-1340 Invited lectures

1340-1530 Lunch break

1530-1710 Invited lectures

1800-1930 Poster session

2000 Gala dinner

Friday, October 24th 2014

0900-1045 Plenary lectures

1045-1115 Coffee break

1115-1320 Invited lectures

1330-1400 Closing ceremony and awards

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Program of lectures Thursday, October 23th 2014 Plenary lectures: 0930-1115 (Amfiteatar I)

Chairmen: Vesna Babić-Ivančić , Vukoman Jokanović

0930-1005 Basic principles of materials design in refractory, process technology and nanomedicine, based on nanotechnology Vukoman Jokanović The Vinča Institute of Nuclear Sciences, Belgrade, Serbia 1005-1040 Mechanisms of in vitro and in vivo crystallization of calcium phosphates

Vesna Babić-Ivančić The Ruđer Bošković Institute, Zagreb, Croatia

1040-1115 Plasma - PVD technology: customized nano coatings for solar applications Ilija Nasov Institute of Physics, St. Cyril and Methodius University, Skopje, Macedonia Break until 1135

Invited lectures: 1135-1340 Section: Refractory (Amphitheater I)

Chairmen: Tatjana Volkov-Husović, Mirko Gojić 1135-1200 Implementation of non-destructive methods for monitoring the degradation of

refractory materials exposed to thermal shock Tatjana Volkov Husović Faculty of Technology and Metallurgy, Belgrade, Serbia 1200-1225 Refractory materials used in the process of lead production

Branislav Nikolić Engineering Academy of Serbia

1225-1250 The mineral raw materials and methods of their preparation for the use in the

refractory and process industry Ljubiša Andrić Institute for Technology of Nuclear and Other Mineral Raw Materials, Belgrade, Serbia

 

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1250-1315 Refractory and ceramic resources of Bosnia and Herzegovina Amir Baraković Faculty of Mining, Geology and Civil Engineering, Tuzla, Bosnia and Herzegovina

1315-1340 Refractory in cement industry Goran Lazić Lafarge BFC, Beočin, Serbia

Section: Process industry (Hall II)

Chairmen: Željko Kamberović, Anka Trajkovska Petkoska

1145-1210 Copper, nickel and alumina based nanocomposites: different architectures

and applications Željko Kamberović Faculty of Technology and Metallurgy, Belgrade, Serbia

1210-1235 Impact of roughness of Zn-Mn coatings on corrosive stability

Milorad Tomić University of Eastern Sarajevo, Faculty of Technology Zvornik, Republic of Srpska 1235-1300 Polymer surface engineering by using advanced nanotechnology

Anka Trajkovska Petkoska The St. Clement of Ohrid University of Bitola, Macedonia

Break until 1530

Invited lectures: 1530-1710

Sections: Refractory and Process industry (Amphitheater I)

Chairmen: Amir Baraković, Mira Vukčević

1530-1555 Harmonization of European regulations and standards (EN) and the national

standards (SR) in the field of refractory materials Sanja Martinović Institute of Chemistry, Technology and Metallurgy, Belgrade, Serbia

1555-1620 Low cement concrete: composition, properties and application

Milica Vlahović Institute of Chemistry, Technology and Metallurgy, Belgrade, Serbia

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1620-1645 Catalysts: from nanotechnology to the application Nenad Radić Institute of Chemistry, Technology and Metallurgy, Belgrade, Serbia

1645-1710 Improving the quality of new supplementary materials for arc welding

Nikola Bajić Institute for Chemical Power Sources, Belgrade, Serbia

Section: Nanotechnology (Hall II)

Chairmen: Dušan Milivojević, Božana Čolović

1530-1555 Surface active substances in the synthesis of inorganic materials Maja Dutour-Sikirić The Ruđer Bošković Institute, Zagreb, Croatia

1555-1620 Biomimetic designing of carriers and controlled drug release

Božana Čolović The Vinča Institute of Nuclear Sciences, Belgrade, Serbia

1620-1645 Carbon nanostructured materials: theoretical aspects and applications in

electronics and medicine Duško Borka The Vinča Institute of Nuclear Sciences, Belgrade, Serbia

1645-1710 Electron paramagnetic resonance and nanomaterials

Dušan Milivojević The Vinča Institute of Nuclear Sciences, Belgrade, Serbia

1730-1900 Poster session

Friday, October 24th 2014 Plenary lectures: 0900-1045 (Amphitheater I)

Chairmen: Ilija Nasov, Rebeka Rudolf

0900-0935 Methods of corrosion protection of dental alloys and characterization of coatings Rebeka Rudolf

Faculty of Mechanical Engineering, Maribor, Slovenia

 

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0935-1010 Correlation between microstructure and functional properties of memory shape alloys Mirko Gojić Faculty of Metallurgy, Department for Physical metallurgy, Sisak, Croatia

1010-1045 Properties of red-mud based geopolymers as a function of raw mixture and activator characteristics Mira Vukčević Faculty of Metallurgy and Technology, Podgorica, Monte Negro

Break until 1115

Invited lectures: 1115-1320 Section: Nanotechnology (Amphitheater I)

Chairmen: Dejan Marković, Slavoljub Živković 1115-1140 Biological aspects of the application of nanomaterials in tissue engineering

Dejan Marković Faculty of Stomatology, Belgrade, Serbia

1140-1205 Bone tissue engineering in maxillofacial region

Petrović Milan, Faculty of Stomatology, Belgrade, Serbia

1205-1230 Nanomaterials in endodontics

Živković Slavoljub Faculty of Stomatology, Belgrade, Serbia

1230-1255 Biocompatibility and bioinductivity of materials based on calcium silicates and hydroxyapatite

Violeta Petrović Faculty of Stomatology, Belgrade, Serbia

1255-1320 Advanced integrated electron spectroscopy techniques for the haracterisation of the surface of nanostructured metallic materials

Monika Jenko Institute of Metals and Technology, Ljubljana, Slovenia

 

Abstracts  

 

 

Plenary lectures

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Basic principles of materials design in refractory, process technology and

nanomedicine, based on nanotechnology

Vukoman Jokanović The Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia

Influence of nanotechnology on the structure and physical and mechanical properties of various materials used in the refractory, process industry and finally nanomedicine is very high. The initial structure of various components in such complex systems was studied in numerous papers in which fine details of system geometry and structure were pointed. Although most of the components belonging to the refractory materials are much larger than the nanometer size, advanced approaches to these technologies assume full understanding of special role of components with nanometric dimensions. The problem of adjusting the rheological properties of various casting mixtures is one of the main problems that can be solved on the base of nanotechnology experience, to obtain easily flowable mixtures with high green density, and finally sintering density after their thermal treatment in situ in the case of monolithic refractory linings. These properties are crucial from the aspect of material functionality, its corrosion resistance to the influence of various corrosion media and erosion, and abrasion properties. All this indicates that nanotechnology is one of the most important factors in design of such materials.

The similar conclusions can be drawn for any kind of material, ceramic or metal, because the design of micro-phases between grains of its matrix is the most important for behavior of the material in practice. Various processes as quenching should be conducted to enable development of these micro-phases of desired design which is the most important for functions of corresponding materials. Synthesis of very active calcium silicate phases using colloid technology combined with the technology of self propagating combustion waves, in our investigations, significantly improved the setting rate of these components of dental cements, while in the case of tetra calcium phosphate, whisker phase obtained by inverse micelle method, the material showed unusual high mechanical properties. Special attention was dedicated to materials which can be used in tissue engineering, like hydroxyapatite, from the aspect of particle size and shape of the initial hydroxyapatite powder, obtained by various technologies. In every case the obtained powder was specific from the aspect of its particles shape and specially diameter: length ratio. The powder synthesis was only the first step in obtaining the scaffold, using different techniques. The aim was to obtain the structure with very pronounced geometrical design which includes macro level, micro level and finally nano level, very important for cell adhesion and attachment of filopodia during cell adhesion and free proliferation of cells in all directions.

 

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The production of starting components in all of these cases includes various nanotechnology techniques. It can be concluded that nanotechnology enables the creation of materials which have great potential for practical application in many areas.

Mechanisms of in vitro and in vivo crystallization of calcium phosphates

Vesna Babić-Ivančić The Ruđer Bošković Institute, Zagreb, Croatia

Calcium phosphates (CaP) continue to attract considerable research interest due to their role not only in biological (bones, teeth) and pathological (urinary and/or kidney stones, carries) mineralization, but also in precipitation processes in natural and industrial waters, as well as in production of fertilizers, ceramics, bioimplants, etc. Formation, i.e. precipitation of calcium phosphates has been investigated both in vitro and in vivo in various fields (chemistry, physics, medicine, biology, materials sciences). The results obtained in in vitro investigations of CaP formation under different conditions contributed to our understanding of mechanisms of their formation in vivo, and vice versa. As formed calcium phosphates can be of different composition, crystallinity and morphology, in recent years this knowledge is used in preparation of novel materials for specific applications, like hard tissue engineering and etc.

 

 

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PVD plasma technology and design of nanocoatings for solar thermal absorbers

Ilija Nasov 1, Anka Trajkovska Petkoska2

1PLASMA – Center for plasma technologies, Skopje, Macedonia 2University Sv.Kltment Ohridski, Bitola, Macedonia

Solar thermal collectors are mainly used for water and space heating. They capture

incident solar radiation, convert it to usable thermal energy, and transfer the energy into a heat transfer fluid. All of this should be accomplished economically with minimum energy loss. One of the most important components of the solar thermal collector is the solar absorber. To be effective, the absorber should exhibit wavelength selectivity, i.e. have maximum solar absorbance, minimum solar reflectance and thermal infrared emittance. A high solar absorbance is needed to collect as much of the incident solar radiation as possible and a low thermal infrared emittance is needed to minimize radiant energy losses. A lightweight materials (copper or aluminium) having a high thermal conductivity is needed to transfer the absorbed energy from surface to the fluid which has to be heated.

Spectral selective coatings are composed of islands of metal embedded in a three-dimensional matrix of dielectric. Recent researches of authors are on mixtures of titanium nitride and titanium oxide that has yielded spectral selective coatings with a solar absorbance of α > 0.95 and an emittance, ε < 0.55. In most cases, they are TiNxOy coatings that are manufactured by Physical Vapour Deposition process – combination of magnetron sputtering and cathodic arc evaporation deposition;

TiNxOy film possesses excellent absorbance towards visible light, in which most of solar energy lies, and good transmittance for the infrared region. This new “blue” coating, based on Titanium, marked a significant increase in performance and represented one of the first environmentally friendly alternative to the so far commonly used “Black-Chrome”- and “Black-Nickel”- coatings. In this work, the TiNxOy coating is deposited by magnetron sputtering and cathodic arc evaporation deposition process in Ar/N2/O2 environment onto aluminium, copper and glass substrates.

Finally, authors present some new types of coatings on different substrates as glass, metals and polymers, two and three dimensional absorbers for solar thermal collectors.

 

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Methods of corrosion protection of dental alloys and characterization of coatings

Rebeka Rudolf1,2

1University of Maribor, Faculty of Mechanical Engineering, Slovenia 2Zlatarna Celje d.d. Slovenia

In this lecture a compressive overview will be presented of the typical composition, mechanical and physical properties of two group dental alloys (basic and noble) in connection with their corrosion resistance. Namely, formatted corrosion products of dental alloys tend to seal the marginal gap and inhibit the entering of oral fluid and bacteria. According to this, it is known that in most cases corrosion of the dental restorations and prostheses in the oral environment is undesirable. In this manner it could be concluded that no dental device (including restorative materials) is absolutely safe for the human organism.

The first group of dental alloys represents austenitic (316) and, rarely martensitic (440) stainless steels alloys which have a variety of uses in dentistry. A common example of corrosion of these dental alloys is rusting of iron caused by a complex chemical reaction which is the final result in the formatting of the oxide Fe2O3×H2O. This oxide is porous, weaker and more brittle than the metal from which is formed. One method to prevent such types of corrosion is to alloy these materials with chromium, Nickel and Molybdenum to form stainless steel. A second one is to perform treatments of the upper surfaces with different coatings.

The second groups of alloys represent noble and high noble, which are usually stable chemically and they do not develop significant corrosion; the major components of these alloys are gold, palladium, and platinum. However, we must take into consideration the fact that in this metals group silver is not considered as noble by dental standards since it will react with tissue fluid, air and sulphur to form silver sulphide, a dark discoloration product. Because silver is still used widely for the production of noble dental alloys as one of main metals it is clear that problems with corrosion do still exist. For these purposes different techniques of electro-depositions of the noble metals on the upper surface for such alloys are used. One of them will be presented as successful praxis in the firm ZlatarnaCeljed.d..

Finally, characterization techniques will be presented which enable the overview and identification of a formatted protective layer, as well as the determination of chemical compositions.

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Correlation of microstructure and functional properties of shape memory

alloys

Mirko Gojić1, Borut Kosec2, Stjepan Kožuh1 1 University of Zagreb, Faculty of Metallurgy Sisak, Sisak, Croatia

2 University of Ljubljana, Faculty of Natural Science and Engineering, Ljubljana, Slovenia

Shape memory alloys (SMAs) belong to a group of new functional metallic materials. They are used in different fields: medicine, electrical and electronic industry, machine industry etc. Shape memory effect is a remembrance of previously deformed shape of the material, and in physical sense is a consequence of martensitic transformation in structure of a homogeneous substance. Necessary condition for obtaining the shape memory is the presence of the reversible phase transformation of austenite (high-temperature phase) in martensite. This transformation is obtained by mechanical (deformation) or thermal methods (heating and cooling).

Numerous alloys show shape memory effect. In this paper, an overview of the most important three groups of alloys: Ni-Ti alloy (nitinol), Cu-alloy (Cu-Zn-Al, Cu-Al-Ni, etc.) and iron based alloys (Fe-Pt, Fe-Mn-Si, etc.) will be presented. Besides nitinol, copper-based alloys (CuZnAl, CuAlNi) have the highest application, which are much cheaper and relatively easy to produce, and they are used as sensor, actuator, etc. Also, production methods of these alloys such as “melt-spinner” technique (rapid solidification), production of alloys by conventional and continuous casting, etc. will be presented. Besides the development trend and characterization of these alloys, a part of our own research, obtained on nitinol and copper based alloys, particularly from the standpoint of their production (casting), heat treatment, microstructure and functional properties (hardness, corrosion resistance, etc.), will be presented in this work.

 

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Properties of Red-Mud based geopolymers as a function of Raw Mixture and Activator characteristics

                                         M. Vukčević, M. Krgović, I. Bošković

Faculty of Metallurgy and Technology, Univeristy of Montenegro, Podgorica, Montenegro

A wide spectrum of by-products enriched with the alumosilicates (ashes, slags, construction remainings, red mud) can be used for the synthesis of geopolymers. Red mud, as the by-product in aluminum industry can be activated by a highly concentrated alkaline solution (sodium hydroxide and sodium-silicate) in the presence of silicon binder. This study presents the influence of relevant parameters as the content of initial mixture and characteristics of alkaline activator and different types of binder, on performances of geopolymers with the aim to obtain satisfactory mechanical characteristics. The level of characteristics of these materials shows all the advantages of these constructive materials in respect to portland cement. The most convenient combination of the parameters can be defined with the aim to enable the use of red mud as the precursor in geopolymers production.

 

Invited lectures

 

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Refractory Implementation of non-destructive methods for monitoring the degradation

of refractory materials exposed to thermal shock

Tatjana Volkov Husović Univeristy of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia

The purpose of this study was to investigate possibilities of using non destructive testing methods for additional thermal shock monitoring of refractory castable. Samples based on low cement high alumina castable sintered at 1300 °C with a dwell time of 3 hours were used in this paper. Thermal stability of refractory samples was tested using standard laboratory procedure of water quench test (ICS 81.080 SRPS B.D8.308 former JUS B. D8. 306). Program for image analysis Image Pro Plus was applied for monitoring destruction at the surface of the sample before and during testing. Ultrasonic pulse velocity testing (UPVT) was applied to measure ultrasonic velocities before and during the testing with the aim of monitoring the changes inside the bulk. Obtained results were used for analysis of samples degradation level before and during the testing. Based on the obtained results, models for strength degradation of the samples during the thermal shock were proposed. Proposed models were compared with the experimental values of compressive strength degradation during the thermal shock. Strength degradation that defining life time of the samples was obtained based on the analysis of the results for monitoring sample behavior due to rapid temperature change.

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Refractory materials used in the process of lead production

Branislav Nikolić1, Vesna Vujačić2

1 Engineering Academy of Serbia, Belgrade, Serbia 2 Institute of Chemistry, Technology and Metallurgy, Belgrade, Serbia

About 90% of the total lead is produced by pyrometallurgical processing of flotation lead-sulphide concentrates (PbS) and waste lead accumulators (aku-waste). By roasting, sulfides convert into oxides (PbO) which are processed in blast furnace at about 1200 ° C to obtain the raw lead. During roasting, sulfur from the concentrate releases as SO2 which is conducted into the plant for the production of sulfuric acid, and in this technological line sulphureous-acid refractory materials are used.

Raw lead contains many useful metals (Cu, Sb, Ag, Bi, Au) which are separated from the lead by refinery and are valorized into commercial products by specific processes.   In kettle furnaces for refining, standard refractory materials for operating temperatures up to 850 ° C are used.

Bismuth is produced in chlorine process, so walls of settling chamber for process gases (up to 600 ° C) and the chimney should be resistant to chlorine and chlorides.

Batches of reverberatory furnaces for processing of copper dross, and short-drum furnaces for processing of aku-waste and As-Sb dross have a high content of soda (NaOH, Na2CO3), and operating temperatures are about 1100 °C.

Batches of   retort and cupellation furnaces for the production of gold and silver have high zinc content and operating temperatures of about 1100 °C.

Therefore, in certain processes i.e. in certain metallurgical furnaces, refractory materials should be used according to the operating temperature, but also depending on the chemical composition of the treated material.

Burner holes, casting of the material from the furnace, batching and other specific parts of the furnace are particularly burdened, and they should be specially treated and strengthened, which significantly contributes to the long working life of the aggregate.

 

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Mineral raw materials and preparation methods for application in refractory and process industry

Ljubiša Andrić

Institute for Technology of Nuclear and other Mineral Raw Materials, Belgrade, Serbia

Basic request for the non-metallic mineral raw materials and components which are applied in the manufacturing of different refractory materials is to be bearers of minerals and oxides necessary for the formation of adequate structure of the refractory material. It should be highlighted that these raw materials should not contain impurities which could decrease final properties of the product and negatively affect the course of its manufacturing. Basic raw materials and components, on whose application the manufacturing of the refractory materials is based, in wider belong to the group of silicates, alumo-silicates, oxides and carbonates. From the natural resources the components are: kaoline, refractory clays, silimanite group of minerals (silimanite, andalusite, kyanite), bauxite, quartz, quartzite, magnesite, chromite, dunite, olivinite, zircon. Besides natural raw materials for manufacturing of various types of refractory-ceramic materials, the materials obtained via chemical processing of natural materials or via synthesis are used. In group of such materials are: technical alumina, synthetic magnesium-oxide, mullite, electrically melted quartz, deposited calcium carbonate, synthetic gypsum, synthetic wollastonite, etc. Reserves of quality refractory clays have been significantly depleted in past years, and if serious measurements regarding preservation of existing foundations of these raw materials are not conducted, the Serbian refractory industry will remain without raw material basis. Having in mind acute problem of raw material basis, the investigations planned for following years should be conducted in rest of interesting and potential parts of Serbia. As a part of a complex consideration of the problem of refractory clays in Serbia, physico-chemical, mineralogical and technological researches should have a huge part in

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finding of the adequate solutions for obtaining quality materials from the clays of lower quality.

At the same time, technological investigations should be initiated regarding application of adequate methods of enriching clays of lower quality in order to obtain synthetic raw material which are fulfilling the requested quality. These researches are based on the fact that Serbia has large quantity of non-metallic mineral raw materials for process industry, which is going to be discussed in the paper.

Refractory and ceramic resources of Bosnia and Herzegovina

Amir Baraković Faculty of Mining, Geology and Civil Engineering, University of Tuzla, Bosnia and

Herzegovina Refractory and ceramic resources of Bosnia and Herzegovina are characterized by insufficient degree of exploration and low level of technological knowledge. In the overall potential of these resources there are significant deposits of kaolin, bentonite, ceramic and brick clay, dolomite and limestone and quartz sand, quartzite, talc and magnesite, whose evaluation is possible. Based on the current level of knowledge on the potential of raw material and perspectives, it can be concluded that Bosnia and Herzegovina is abundant in various deposits and occurrences of natural resources, classified in more ore regions within the inner and central Dinarides. Deposits and occurrences of the mentioned resources, in genetic terms, are related to the zone of the Cenozoic Neo-Alpine autonomous activation and sediment-genesis in the Neogene lakes and lagoons, or to multiphase polygenetic geodynamic movements and processes whose activity was strongest in the Oligo-Miocene with calming in the Pliocene and the Quaternary.

A multiple application of refractory and ceramic raw materials in the process industry is possible, as a crude or refined ore whose composition is adjusted by different recipes and demands of the industry. The quality and application of these materials in various industries determine the chemical and mineralogical composition and technological parameters of homogeneity in the final product. The main qualitative parameters of the listed refractory and ceramic raw materials of Bosnia and Herzegovina are shown in this work.

 

 

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Refractory in cement industry

Goran Lazić Lafarge, Beočin, Serbia

 

The concept of refractory in its original sense, as well as refractory in the industry, is very broad term. Consequently, each segment within the global notion has its own similarities and particularities. The common denominator in every aspect of refractory is the need of opposition to high temperature, abrasive reactants, thermochemical processes between reactants and also between the reactants, technological fuel and refractory material etc. Number of similarities is long. Of course, there are differences. Some of them are outstanding, some are small-scale.

Mutual similarities give the space to provide universality, and thus simplify the work with all its benefits. Mutual differences give the space to creativity, scientific research, learning and improvement, both in technical and technological terms, and of course, to the safety of work. A specific review of refractory in cement industry will be given in this work.  

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Harmonization of European regulations and standards (EN) and the national standards (SR) in the field of refractory materials

Sanja Martinović

Institute of Chemistry, Technology and Metallurgy, University of Belgrade

Technical Committee for standardization of Serbia, KS B033 - Refractory materials, which is operating withinin the Institute for standardization of Serbia has the task to prepare the standards in the field of raw materials and products of the refractory materials industry with monitoring the work of Technical Committees: CEN/TC 187-European Committe for Standardization (CEN): Refractorory products and materials and ISO/TC 33-International Organisation for Standardization (ISO): Refrectoriess. Harmonization of Serbian standards with European ones are based on the adoption of European standars as national and especially European standards that are directly related to implementation of the New Approach Directives. In addition, by adopting the European standards as Serbian, all national standards for the same items of standardization that are inconsistent with them, must be withdrawn. This presentation would give the basic information related to the published standards in the fields of Refractory materials, primarily referring to the European standards. Also, the Committee’s work program which is adopted by the Expert Counsil of the ISS will be shown. The Committee has the plan to adopt the national standards related to the environmental management in the field of refractory materials. This presentation will show specifically standard for shaped refractory products - sampling and acceptance testing on admission of the samples together with the statistical assessment (ISO 5022).

 

 27  

Low cement concrete: composition, properties and application

Milica Vlahović Institute of Chemistry, Technology and Metallurgy, University of Belgrade, Belgrade, Serbia

Today’s low cement refractory castables are refractory concretes with the most of 5 % calcium-aluminate cement and the content of CaO in the range of 0-1.5 % while the content of water should be 4-6 %. Modern low cement concretes have the composition that provides a dense packing of particles, high density and low porosity. Such composition involves the use of fine and ultra-fine particles, additives or active deflocculants and other powders thus preventing the agglomeration of particles and increasing the zeta potential of oxide grains in concrete, and thereby reducing the required amount of water for the preparation of concrete. Modern low cement concretes show superior physical properties compared to other monolithic or shaped refractory materials of similar composition (content of Al2O3). The improved properties include small porosity, high density, ultra high strength, resistance to corrosion, erosion and abrasion, thermal stability and resistance to the effects of slag, excellent resistance to mechanical and thermal spalling. Development of low and ultra-low refractory concretes significantly increases the scope of application, even in cases where the only solution was lining of the refractory bricks. Advantage in comparison with the shaped refractory products is primarily economic (lower cost of production and application), but also they can be simply applied in case of complex shapes and difficult to reach areas. Nowadays, applications of low cement concretes are numerous in almost all areas of industry: metal (iron and steel), cement, chemical, petrochemical, nuclear, in hydrocarbon waste incinerators, power plants, and etc. It should be emphasized that low cement concretes can be sucessfully used for repairing the damaged refractory lining.

  28  

Process industry Coopper, nickel and alumina based nanocomposites, different architectures

and applications

Marija Korać1, Zoran Anđić2, Željko Kamberović1

1Faculty of Technology and Metallurgy, University of Belgrade, Belgrade, Serbia 2Innovation Center of the Faculty of Chemistry, Belgrade, Serbia

Considering that nanostructural materials are expected to have special physical and mechanical properties, in the recent years the examinations of synthesis and characterization of the nanocomposite system attracts even greater scientific interest. This paper presents production of sintered contacts materials produced from nanocomposite powders obtained by combination of thermochemical synthesis of Cu-Al2O3 powder and mechanical alloying of atomized copper powder with previously synthesized Cu-Al2O3 powder. Produced powders were characterized by X-ray diffraction and Analytical Electron Microscopy. Characterization of sintered samples included Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), measurement of hardness and specific electrical conductivity. By thermochemical method of Cu-Al2O3 nanocomposite synthesis, i.e. deposition from aqueous solutions, in combination with mechanical alloying, significant effects of reinforcement were achieved as a result of homogenous distribution of alumina in the nanocomposite system.

In combination with conventional methods, thermochemical process of nanocomposite powders synthesis could be successfully applied for synthesis of new nanocomposite catalysts, which are characterized by a high degree of dispersion of the catalytically active component, respectively the catalyst with high activity and selectivity. The high degree of dispersion is the result of uniform distribution of the catalytically active component into alumina suspension, realized during the thermochemical treatment in the synthesis of nanocomposite catalysts. In accordance with this, the paper shows the synthesis of Ni/Al2O3 and Ni-Pd/Al2O3 nanocomposite catalysts with homogeneously dispersed Ni particles, as catalytically active component, and Pd, as activity modifier, supported on ceramic Al2O3 based foam. Namely, the previous synthesized monolith was soaked in a mixed alumina suspension with NiCl2, PdCl2 and appropriate organic additives in order to obtain nanocomposite catalysts with homogeneous distribution of catalytically active components. Characterization of obtained Al2O3 foam, as the active catalytic components primary carrier, and synthesized nanocomposite catalysts included SEM, EDS, gas permeability and mechanical properties.

Synthesis of nanocomposite materials with homogeneous distribution of particles on the nanometer level may lead to formation of new materials with improved or even unexpected properties.

 

 29  

Impact of roughness of Zn-Mn coatings on corrosive stability

Milorad V. Tomić1, Milan G. Riđošić1, Miomir G. Pavlović1, Miroslav Jokić1, Jelena Bajat2

1University of Eastern Sarajevo, Faculty of Technology Zvornik, Republic of Srpska 2University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia

This paper involves electrochemical deposition of Zn-Mn coatings from four solution, we measured their roughness and corrosion stability. We used cathodes made of steel of unknown composition that were licensed under the chemical preparation before the electrochemical deposition of dual-Zn-Mn coatings, and we also used the anode of zinc, purity of 99.99%. Dual Zn-Mn coatings were electrodeposited for 15 minutes from all of the solutions at a current density of 1 A/dm2, 2 A/dm2 and 4 A/dm2. All experiments were carried out in galvanostatic (at constant current) in an electrochemical cell, volume of 500 cm3 and at room temperature.

The roughness of electrochemically deposited Zn-Mn coatings was measured by a device TR200 and corrosion stability of deposited coatings by determining the electrochemical impedance spectroscopy (EIS). The results show that the coatings with the smallest roughness are coatings deposited at a current density of 2 A/dm2 from all of the solutions. The exception is the solution 3 with the relation [Mn2 +]:[Zn2 +]=1:2 where the roughness is at the lowest level in comparison to all solutions, ranging from 0.71 to 0.875 µm, and the roughness is lowest at the current density of 4 A/dm2 and is 0.71 µm. Based on electrochemical measurements, the corrosive most stable Zn-Mn coating is deposited at a current density of 2 A/dm2 from all the solutions and at the current density of 4 A/dm2 from solution 3 with a ratio of [Mn2+]:[Zn2+]=1:2. This suggests that the corrosion stability is directly related to the roughness and compactness of Zn-Mn coatings. When it comes to corrosion, the most stable coatings are those with the lowest roughness.  

 

 

 

 

 

 

 

 

  30  

Shaping of polymeric material by use of soft lithography

Anka Trajkovska Petkoska University St. Kliment Ohridski, Bitola, R. Macedonia

Soft lithography as a technique has been used for replicating structures with

micrometer or nano-dimensions with an elastomeric mold or stamp. In this study, soft lithography technique has been used for manufacture regular forms of polymer cholesteric liquid crystal material. Liquid crystals (LCs) represent a special condensed matter phase, which belongs between the disordered isotropic liquids and the well-ordered solid crystals. They possess the fluidity of a liquid phase, and at the same time have a certain degree of the orientational and/or positional order like in a crystal lattice. LC materials show pronounced anisotropic (optical, electrical, magnetic, and mechanical) properties due to their rod-like or disk-like nature of their molecules. Cholesteric liquid crystals (CLC) are materials, which exhibit unique optical properties, such as selective reflection and circular polarization due to their helical structure. With proper molecular design, polymeric CLCs with varying pitch lengths that reflect color from deep UV- to far IR- region can be made. Polymer cholesteric liquid crystals (PCLCs) posses fixed selective reflection color. The long-chain macromolecular nature of PCLC materials may result in glass-formation, processing into films, good mechanical and thermal stability. Also, PCLC could be made into shaped micro-particulate forms by use of soft lithography. It is an inexpensive technique that uses a flexible patterned elastomeric mold, polydimethylsiloxane (PDMS) mold. Patterning of the PDMS mold happens after curing of PDMS material over patterned silicon wafer that serves as a template. Different shaped polymeric microparticles have been produced in this way like, rectangular, square, oval shapes etc. Shaped PCLC microparticles have been characterized by different techniques viz polarized optical microscopy, scanning electron microscopy, white light interferometry and other techniques. PCLC films and microparticles could find multiple applications such as: notch filters, reflectors, polarizers, sensor applications. Among many potential applications, the most attractive application of regularly-shaped PCLC microparticles is as the low-cost alternative to the existing liquid crystal displays, and particularly, the particle display technologies, due to their multi-color availability and low power consumption.

 

 

 

 

 

 

 31  

Catalysts: from nanotechnology to the application

Nenad Radić IChTM-Department of Catalysis and Chemical Engineering, University of Belgrade,

Belgrade, Serbia

In recent general usage, nanotechnology is any technology related to features of nanometer scale: thin films, fine particles, chemical synthesis, advanced microlithography, and so forth. A technology based on the ability to build structures to complex, atomic specifications by means of mechano-synthesis; this can be termed molecular nanotechnology. Today's nanotechnology harnesses current progress in chemistry, physics, materials science, and biotechnology to create novel materials that have unique properties because their structures are determined on the nanometer scale.

Heterogeneous catalytic chemists have always known that size matters. Since catalysis is a surface effect, and active surface is a function of particle size, it is obvious that particle size is an important variable. One of the main objectives of catalysis research is to design and tune activity and selectivity of catalysts by controlling their structural properties at the atomic level. In this article the current understanding of the active catalytic site and the reaction mechanism is reviewed. The recent progress with respect to volatile organic compounds oxidation on Pt/Al2O3 catalysts with different platinum mean crystallite size, small and large, is summarized. The effects of the addition of manganese on the performance of small and large Pt crystallites are also reported.

Another important aspect is the way in which catalyst materials are implemented into catalytic reactors. Many catalytic devices used in industrial catalysis are based on monolithic supports in which catalytic reactions occur in channels, porous walls and other confined cavities for which coating of catalyst thin films is required. Thin oxide films as catalysts and catalyst supports are of great importance to control the functional characteristics and, thus their intrinsic catalytic properties. Several challenges can be mentioned in relation to the development of these catalyst thin films in terms of thickness, surface area, control of porosity and catalyst accessibility. Thin oxide films can also take advantage of the new generation of microporous and mesoporous solid materials for the preparation of supported catalyst layers able to exhibit high surface area and hierarchic porosity. Spray pyrolysis is very simple and relatively cheap processing method to deposit thin films or coatings on different substrates. Also, this method offers great versatility due to the large number of adjustable process parameters, such as: spray geometry, substrate temperature, atomization technique, composition and concentration of precursor, liquid and gas flow rates. Thin films deposition, current status and progress in the field of spray pyrolysis will be discussed in this review. The influence of process parameters of spray pyrolysis on film  structure and properties  of various oxide films will be illustrated with some examples.

  32  

Improving quality of new filler for arc welding

Nikola Bajić Research and Development Center, IHIS Techno-experts d.o.o., Belgrade, Serbia

This paper provides an overview and an analysis of the results achieved in the development and production of new fillers with enhanced additional features of the shape and type of flux-cored wires and special electrodes intended for arc welding.

Particular attention is paid to the development of new flux-cored wires based on domestic raw materials with improved quality compared to conventional cored wires. Development and organization of production of new cored wires is followed by changes in the shape of the cross-section and composition of the active core. The thickness of the narrow steel strip used for making a new flux-cored wire was increased multi fold compared to the strip used for producing classical cored wire. For mastering production of new cored wires an experimental technological line for the calibration of narrow steel strip and formation of flux-cored wires was set up. The produced new quality of flux-cored wires, designed for the MAG and submerged arc welding process, in the course of experimental welding showed satisfactory operational welding features and the required quality of the welded joint as evidenced by the obtained test results.

Development work on improving the quality of the coated electrodes for welding and surfacing is based on the use of flux-cored wire, instead of solid wire, for creating the core of the coated electrodes and represents continuity in the development of flux-cored wires with a higher degree of processing. Mastering production of a special coated electrode with a core of flux-cored wire was performed on an experimental line for coating, and then experimental welding and testing of welded joints was performed. The results obtained indicate the feasibility of continuing the research and development work on the development of new metallurgical quality of special coated electrodes.

 

 33  

Nanotechnology

Surface active agents in the synthesis of inorganic materials

Maja Dutour Sikirić Ruđer Bošković Institute, Division of Physical Chemistry, Zagreb, Croatia

Surface active agents (shorten surfactants) are organic compounds containing in one molecule both lyophobic (hydrophobic) and lyophilic (hydrophilic) parts. Due to such amphiphilic structure surfactants exhibit specific properties in solutions (as well as in solid state). When present at low concentrations in solutions they adsorb at all available interfaces (liquid/gas, liquid /liquid, liquid /solid,) and as a consequence dramatically change their free energy. At higher concentrations, above so called critical micellization concentration, when all the interfaces are occupied, surfactants self-assemble in the bulk in various aggregates: micelles, vesicles and liquid crystals. Surfactants versatile phase behavior and ability to form different structures, with sizes from nano to micro-scale, is a reason why they are widely used in various applications and industrial processes, ranging from classical to modern technologies. Although surfactants have been used in the synthesis of inorganic materials for a number of years, either as soft templates or in the surfactant mediated synthesis, it is their role in the synthesis of nano-materials which renewed interest in applying novel surfactants in the synthesis of inorganic materials.

  34  

Biomimetic designing of carriers and controlled drug release

Božana Čolović, Vukoman Jokanović Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia

   

The main problems which scientists and doctors, working in the field of bone tissue engineering, are dealing with are related to processes of osteointegration, implantation and the inflammation at the implantation site.

The problems of biocompatibility and osteointegration of materials used as implants in bone tissue engineering may be solved by the formation of bioactive coatings of calcium hydroxyapatite (CHA) on their surface using biomimetic method. This method enables formation of CHA with similar structural and morphological properties of a natural bone. It is based on the use of the solutions of similar ionic composition as human plasma - simulated body fluids, providing similar conditions of CHA nucleation as in biological systems. Two potential types of implants, metal and ceramic, were used in this study. Prior to biomimetic treatment, the metal surface (stainless steel) was coated with the thin silica film, with OH groups that act as active centers of apatite nucleation. Ceramic substrate- porous CHA scaffold was treated in biomimetic medium in order to improve nanotopology of its inner walls, optimal for growth and activation of bone tissue cells. It was previously functionalized with polymers (PLGA, cellulose and alginate) in order to achieve its additional nanodesigning and increase its surface activity. The phase analysis of the phases formed in the biomimetic medium, confirmed that CHA was formed on the surface of all samples. Also, bio-acceptability of these materials was investigated in vitro and in vivo and very good results were obtained.

The problem of frequent inflammation occurring after implantation, as well as the problem of local treatment of bone tissue diseases, may be solved using controlled drug delivery to the affected area. The main issue is how to develop an implant material that will have required osteoinductive and osteoconductive properties and also act as the local regulator of the release of biologically active molecules at the interface of living tissue and the implant. CHA, as the one of the mostly used materials in bone tissue engineering, was used in this study as a model system to investigate the release kinetics of antibiotics used for healing of bone tissue infections. Antibiotics were encapsulated in two different systems: in the polymer incorporated in CHA scaffold and tablets obtained by compression of CHA powder. Besides CHA carriers, carrier for controlled drug delivery based on SiO2 was also created, using the spray drying method that allows obtaining the SiO2 particles of complex structural design with simultaneous drug immobilization on these particles. The release rate of antibiotics from these systems was measured and it was concluded that suitably designed porous carriers can sustain a drug long enough to control the process of local inflammation.

 

 35  

Carbon nanostructured materials: theoretical aspects and applications in electronics and medicine

Duško Borka

Vinča Institute of Nuclear Sciences, Atomic Physics Laboratory, University of Belgrade, Belgrade, Serbia

Carbon nanostructured materials have attracted great research interest for their potential applications in electronics, energy, materials, biomedical areas and in next generation of electronic devices. In this paper we will focus on interaction of carbon nanostructured materials with charged particle beams, in particular charged particle interaction with carbon nanotubes and graphene surfaces.

The theoretical analysis has shown that the angular distribution of transmitted ions through carbon nanotube contains the information on the transverse lattice structure of the nanotube. The flux redistribution can be manipulated within carbon nanotubes by varying two parameters, the incident ion angle and the initial ion energy. The cross section of the ion beam within the nanotube can be very small; the spatial distribution contains a large, narrow central maximum. We presented here the angular and spatial distributions of transmitted charged particles through carbon nanotubes. Also, we discuss the problems of guiding of charged particle beams by nanotubes and possible applications for creating nanosized charged particle beams to be used in materials science, biology and medicine.

Well understanding of the electronic structure of graphene is a necessary first step for the design of nanoelectronics, chemical/bio-sensors, electrocatalysts, and nanoplasmonics. That is why investigations of interaction with particle in the context of probing plasmon excitations in graphene by using electron energy loss spectroscopy (EELS) are of great importance. It can be used like a novel tool for changing and controlling the electronic properties of carbon nano-materials. We shall present here our studying that include interactions of graphene with external charges that move at high speeds by using a dielectric function for graphene with a two-fluid hydrodynamic model and at low speeds by using a dielectric function for graphene within the random phase approximation (RPA).

  36  

Electron paramagnetic resonance and nanomaterials

Dušan Milivojević Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia

EPR spectroscopy is a method that can be applied to samples that contain unpaired electrons. There is wide range of application of this method which includes research in the field of life sciences (nitric oxide and reactive oxygen species), bioinorganic and inorganic chemistry (transitional metal elements in compounds and in living tissue), petrochemistry, dosimetry, environmental chemistry, pharmaceutical industry, biophysics, food industry and whole range of applications in solid state physics and material science, like research of magnetic properties of materials, free radicals and defects. Most of those applications are well established and some are routinely used. For nanomaterials, a number of physical (mechanical, electrical, optical, catalytic, etc.) properties change when the size of the system decreases compared to macroscopic systems. Quantum effects can become significant when the nanometer size range is reached, typically at size of 100 nanometers or less. The surface area to volume ratio increases altering properties of materials. EPR turn out to be valuable method in nanoscience research and we witness innovative ideas of application. Author reports some applications of EPR in nanomaterials research through examples from his practice, like carbon based nanomaterials, II-VI semiconductor nanoparticles, silver nanoparticles etc. EPR is used to characterize the environment of the unpaired electron, to analyze reactive oxygen species produced by nanoparticles or to follow chemical transformation.  

 

 37  

Biological aspects of application of nanomaterials in tissue engineering

Dejan Marković1, Ivana Karadžić2, Vukoman Jokanović3, Vesna Vučić2

1 Department of Paediatric and Preventive Dentistry, Faculty of Dentistry, University of Belgrade, Belgrade, Serbia

2 Centre of Research Excellence in Nutrition and Metabolism, Institute for Medical Research, University of Belgrade, Belgrade, Serbia

3 Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia

Stem cells and scaffolds have an essential role in the production of new tissue by tissue engineering. Cellular component is necessary for generation and establishment of extracellular matrix in the new tissue, while scaffold provides mechanical stability and foundation of a new three-dimensional tissue organization. All dental pulp stem cells have characteristics needed for successful therapeutic applications: isolation is simple and efficient, they have multipotent potential, and can be successfully stored long-term by cryopreservation. Interaction with biomaterials used as matrixes induces intense proliferation of these cells. They can differentiate into odontoblasts, osteoblasts, chondrocytes, adipocytes, neurons, and other cells. Besides cells, the selection of a suitable scaffold material is crucial for bone tissue regeneration. The basis of tissue engineering is to induce tissue regeneration with cell culturing onto three-dimensional matrixes.

We examined the differential capacity of dental pulp stem cells isolated from healthy deciduous teeth with physiological root resorption (SHED) cultured onto four different scaffold materials: porous hydroxyapatite (pHAP) and pHAP combined with three polymers: poly lactic-co-glycolic acid, alginate and poly(ethylene vinyl acetate)/poly(ethylene vinyl versatate). MTT assay didn’t show any significant cytotoxic effect for the tested materials, in the tested concentrations. LDH test showed significant cell proliferation and adhesion to all tested materials. Alizarin red is a marker of mineralization, and the presence of colored complex surrounding the cells indicated osteoblastic differentiation of SHED and newly deposited mineralized matrix which they produced in presence of all tested scaffolds. However, cells cultured on polystyrene (as control) with osteogenic medium but without scaffolds, indicated clearly lower level of differentiation. This result confirmed the importance of scaffold in the process of differentiation. ALP activity is a biochemical marker for osteoblastic phenotype, mineralization and differentiation. After 12 days of culturing, significantly higher ALP activity was found in cells grown with all tested materials than with Bio Oss which was used as control. Scanning electron microscopy showed that, after 21 days of culture in osteogenic medium, in the presence of each material, the extracellular matrix was dominant, covering the scaffold and the pores. In this way, all tested materials proved to be equal, and by many parameters even better than the gold standard in bone tissue engineering Bio Oss. All of these materials enable binding of osteoblasts and osteoblast precursors, their growth and differentiation in vitro.

  38  

Bone tissue engineering in maxillofacial region

Milan Petrović Faculty of Dentistry, Belgrade University, Serbia

The repair of large segmental bone defects due to trauma, inflammation and tumor

surgery remains a major clinical problem. Bone tissue engineering developed into the one of the main fields of research in regenerative medicine in the last decade. It is an alternative approach to conventional bone grafts. The main objective of this type of therapy is to repair, regenerate and reconstruct damaged bone. Scaffolds or cell carriers are essentially in the tissue engineering. Scaffolds have a key function concerning cellular invasion and bone formation. Ideally, a scaffold should have the following characteristics: (i) three-dimensional and highly porous with an interconnected pore network for cell growth and flow transport of nutrients and metabolic waste; (ii) biocompatible and bioresorbable with a controllable degradation (iii) suitable surface chemistry for cell attachment, proliferation, and differentiation and (iv) suitably mechanical properties.

Nowadays, thanks to nanotechnology, we are able to make almost ideal scaffolds. Such scaffolds in combination with stem cells and certain active substances are widely used in many preclinical and clinical researches concerning maxillofacial region. This presentation will present the latest achievements and goals in bone tissue engineering in maxillofacial region.

 

 

 39  

Nanomaterials in endodontics

Slavoljub Živković Department for Restorative Dentistry and Endodontics, School of Dentistry,

Belgrade, Serbia

Nanotechnology is implemented in almost all scientific fields with huge potentials and possibilities in medicine and dentistry. It is based on molecular self-assembly and creating new materials with nanoparticles.

In dentistry, bioactive materials based on calcium silicate and calcium phosphate ceramics are becoming of increasingly great importance. Their physical and chemical properties are being researched while their development and modifications are becoming one of the goals of nanotechnology.

Hydroxyapatite is widely used in dentistry, and it also consists of nanoparticles. It has the ability to integrate in bone structures and support bone ingrowth without dissolving (it is bioactive). It also stimulates osteoprogenitor cells and synthesis of bone matrix. The development of new scaffolds is also a new field of research in regenerative endodontics. Except its mechanical and physical properties, scaffold should also stimulate differentiation of odontoblasts and forming a dental bridge at the place of pulp chamber floor perforation.

Different nanomaterials are used in endodontics nowadays. They are used mostly in cases when the successful outcome is not certain (direct pulp capping, apexogenesis, apexification, pulp regeneration). Porous ceramics, polymers, organic-inorganic hybrids of hydroxyapatite, tricalcium phosphate, bioactive glass and glass ceramics are convenient for application in these cases because they encourage osteoblast differentiation and forming of mineralized tissue.

The use of nanomaterials based on silicate systems in therapy of furcation perforations or as a sealer for root canal opturation, is also an important improvement in solving complex problems in endodontics.

  40  

Biocompatibility and bioinductivity of nanomaterials based on calcium silicates and hydroxyapatite

Violeta Petrović

Department for Restorative Dentistry and Endodontics, School of Dentistry, Belgrade, Serbia

Fast setting of the two newly synthesized endodontic nanomaterials based on calcium silicate (CS) and hydroxyapatite (HA-CS) (10 and 15 minutes, respectively) could be a clinical advantage compared to commercial materials with similar chemical constitution. The purpose of the study was to evaluate in vitro cytotoxicity and in vivo biocompatibility and bioinductivity of a new nanomaterials based on calcium silicates (CS) and hydroxyapatite. Cytotoxicity of a tricalcium and dicalcium silicate system (CS) and a mixture of CS and hydroxyapatite (HA-CS) was tested using the MTT assay on human lung fibroblasts MRC-5 and compared to White Mineral Trioxide Aggregate (MTA Angelus, Soluções Odontológicas, Brazil). Eluates of set materials were tested in 100% and 50% concentrations after 24h, 7 days and 21 days of elution. For biocompatibility and bioinductivity studies, CS and HA-CS, were implanted in root canals of experimental animals (Oryctolagus cuniculus), after endodontic treatment. The animals were sacrificed 28 days later, and the treated teeth with surrounding tissue were submitted to histological processing. The degree of inflammatory cell response and the formation of calcified tissue were determined in the specimens. CS and HA-CS undiluted and diluted eluates showed greater cell viability then MTA at all test periods. In 21-day undiluted eluates, cell viability was greater after treatment with HA-CS than with CS. Diluted eluates of CS and HA-CS resulted in significantly greater cell viability then undiluted eluates of the materials. In the animal model study, there was no significant difference between the tested materials in term of intensity of the inflammatory response. In most of samples, inflammatory reactions were scored as mild to moderate. Neoformation of a calcified tissue was detected in all specimens for all tested materials. CS and HA-CS showed faster formation of calcified tissue compared to MTA. Calcified tissue in HA-CS samples was better organized compared to CS and MTA. CS and HA-CS were less cytotoxic then MTA in vitro. In vivo, CS and HA-CS showed similar biocompatibility and better bioinductivity compared to MTA.

 

 

 

Posters

  42  

Refractory Improving the characteristics of low-cement refractory concrete outside the

shelf life

Goran Lazić Lafarge, Beočin, Serbia

In practice, it often happens for various reasons, that the refractory concrete that we have in stock is not used within its shelf life. This means that after the specified time frame, the manufacturer is no longer liable for its features that are specified in the declaration. Then we find ourselves in a dilemma: to use it or no to use it. If we use it, we risk its damage with all further consequences. If we do not use it, we make a futile expense by removing it from the stock, making damages to our professionalism and vocation of “refractory expert”. There are ways to mitigate this negative effect, as it will be shown in this work.

 

 43  

The installation of refaractory concrete

Goran Lazić

Lafarge, Beočin, Serbia

All involved in the installation of refractory concrete were or will be in a position to have to make an emergency (quick, easy and effective) installation of this material in an inaccessible position of the plant. But, that is not the only demand that an investor can place before you. In other words, the investor does not have the space to cool the plant, which means that you will have to do an intervention from the outside. Furthermore, even if the plant is cooled, the damage is too small or you have to mount a scaffolding twenty feet high in order to reach the site. The cost of scaffolding can be weleveled out accordingly, but difficulty the time required for its assembly and disassembly. These two extremes are sufficient to create a significant dilemma in you as a contractor, in which direction to go!? There are ways to resolve it in an efficient way, as confirmed in practice.

  44  

Methods of preparation of refractory fillers for the synthesis of cast coating

Marko Pavlović1, Tatjana Volkov-Husović1, Ljubiša Andrić2

1University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia 2ITNMS, Belgrade, Serbia

For production of the castings with favorable properties, cast coatings with the advance quality setting must be used. During the castings, the basic role of coating is creation of an efficient refractory barrier between sandy substrate and liquid metal flow. The coating properties required: refractorability; favorable gas permeability; easy application and adhesion to sand mold surfaces and polymer model surfaces; easy adjustment of thickness of the coating layer, high drying rate, without cracking or removal of the dried coating layers, were achieved by optimization of coating composition and their production technology. The most important components of the coating are: the refractory filler, bonding agent, means for holding the suspension and the solvent. As the refractory coating filler used by the various refractories (talc, corundum, cordierite, mica, zircon, mullite, chromite) and their selection is done according to the characteristics: relatively high melting temperature; low heat spread coefficient; it doesn’t soak up liquid metal; it doesn’t produce gases when in contact with liquid metal. Preparation of the fillers is performed according to procedures oF grinding and fragmentation to the grain size 20-40 µm.

An important coating property is the sediment stability of coating suspension. Different kinds and quantities of additives were examined (dextrin, Na3P3O3, carboxymethyl cellulose-CMC, bentone), as well as their activation by mixing, with an aim to enable easy additive absorption to the refractory filler particles, maintenance of the filler in a dispersed state and prevention of the filler build up. A bonding agent within the coating (colophonium-C20H30O2, bentonite, Bindal H), was chosen with regard to the size and shape of the refractory filler particles in order to enable connection of the particles and to secure good adhesion of refractory particles to the observed surface of either the sandy mold or polymer model. As a liquid solvent was used alcohol, as well as water. It appeared that the optimal density of refractory coating was 2 g/cm3. In doing so, it is preferred that the refractory filler, with particles size up to 40 µm, to be used in an amount 92-95%; bonding agent in an amount 2.3-3.5%; additives up to 1.5%, and liquid solvent used to density of suspension up to 1.8 - 2 g/cm3.        

 

 45  

   

Production of SiC based shaped refractory materials for application up to 1450 °C – nonferrous metallurgy, ceramic bond, secondary SiC

Vladimir Vučetić1, Milorad Vučetić1, Nemanja Vučetić2

1Real S, Belgrade, Serbia 2University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia

Purpose of this work is conquest of production of shaped product based on SiC which would have use in nonferrous metallurgy, primarily in production of aluminum, copper, zinc and lead, wherein is necessary refractoriness up to 1450 °C.

Detailed process mechanism of SiC forming in industrial conditions in form of large compact crystals is not clarified, despite to efforts of various authors. Summarized, reaction is: SiO2+3C=2SiC+2CO. According to one scheme of SiC forming process, it is being shown in two stages: in the beginning is formed elementary Si by reaction of C and SiO2, and then, the liquid Si or gaseous SiO react with carbon, wherein β-SiC is being formed. All this take place at relatively low temperature (up to 1400 °C), while formation of SiC is obtained at much higher temperature.

In ceramic mass with suitable granulometric composition, during the sintering process is necessary to bind the basic raw material SiC directly, by secondary SiC or by ceramic bond, e.g. by mullite.

In this work is applied a method of production of shaped SiC refractory material by sintering in oxidizing or neutral environment, at t=1450 °C, wherein it was necessary to enable the sintering process of SiC forming to be carried at low temperatures by adding corresponding mineral agent and preventing of loss of possibly present Si, i.e. SiO, and by oxidation of graphite, while the process of formation of so-called secondary SiC is performed in micro pores of shaped SiC refractory material, and possibly presence of oxygen is being prevented by forming of low melting glassy phase. Converting the β-SiC to α-SiC is performed in process of exploitation or during production process. In this way, the porosity of final product is reduced, density is increased, and finally, as result is obtained product which is concurrent to famous world producers (Norton, Morgan).

               

  46  

   

   Refractory in Serbia: problems and perspectives

Dalibor Stević Real S Ltd Belgrade, Serbia

Current problems in refractory production and consumption in Serbia have been analyzed on the base of numerous data. It has been noticed that domestic producers of refractory materials are in an unequal position compared to foreign companies which sell their products on Serbian refractory market.

The main problem is the lack of the right education, responsible people who work on high positions in companies which are consumers of refractory materials, which usually favor foreign producers on the account of domestic producers, without any rational reason. Beside, week network of domestic refractory producers, their insufficient mutual communication, lack of the right individual and common strategy are also significant reasons for such situation. During last twenty years, previously existing development centers were shut down, together with bankrupt of large industrial centers for the production of refractory materials.

Perspectives are in education of new young experts and networking between experts from this area, connections of various producers with their small companies, with the aim of faster development and implementation of innovative technologies in the practice and more efficient access to the customers of refractory materials.

 

 

 

 

 

 

 

 

 

 

 

 

 

 47  

 

Refractory gunning mixes – new applying possibilities

Vladimir Vučetić, Dalibor Stević, Jovanka Malešević Real S, Belgrade, Serbia

Company Real S, in cooperation with company Albos, has developed gunning mixes with wide application in refractory industry. The gunning mixes have advantages comparing to other refractory shaped or monolithic products because of their possibility to apply on unreachable places, and casts are not necessary. Particular advantage of these mixes is possibility of application to hot surfaces, without need of turning off and cooling the thermal unit. Also, material loss is reduced to 5-10 %, which saves time and money.

We produced semi acidic gunning mixes based on Al2O3 as holder of refractoriness which have wide range of application in thermal power plants, cement industries, etc; also alkali gunning mixes based on MgO as holder of refractoriness which have wide application in ferrous metallurgy. Semi acidic gunning mixes have been successfully used for many years in cement plants Lafarge BFC, Beočin and Holcim (Srbija), Popovac. Alkali gunning mixes were successfully tested in steel smelter Sirmium steel, Sremska Mitrovica.

  48  

Reparation of foundry ladles by refractory mixes

Boro Hinić

Real S d.o.o. Belgrade, Serbia

In older foundries of gray cast iron, for ladle repair chamotte mud is still used. If mix for ladle repair is not dried appropriately, during the casting process the melt can be frequently boiled, influencing formation of scarp and interruption of casting process. Optimal solution for fast repairs should be waterless refractory mixes based on tar and various organic resins, which enables small repairs onto the surface of hot areas of refractory lining. This solution is optimal for such application in domestic consumers of such refractory materials. Therefore, this approach can be observed as promising for experimental investigations and industrial testing in our foundries.

 

 49  

Deposits of boron minerals in Adriatic basin

Nebojša Videnović

Belgrade University, Faculty of Mining and Geology, Belgrade, Serbia

Deposits of boron at Piskanja, Baljevac - Serbia, are unique in this part of Europe. Due to its quality crude ore obtained from this deposit is exported worldwide, as they are India, Italy and Germany. Taking in mind its established reserves and very wide opportunities for processing in more than 102 products this mineral can be observed as strategic resource of national economy. On the base of given data in this paper, potential reserves of boron in corresponding ore deposits are estimated about 7.500.000 tons, with average content of boron around 36%. These reserves are probably significantly larger, due to special structure-tectonic and geologically-mineral-genetic position of deposit, showing so a very big importance for development our economy. For more efficient exploitation numerous questions should be solved, previously, like conditions of exploitation, kind of investigations, maximal allowed distances among particular investigations, distribution of deposits and ore bodies towards of the genetic type and size, categorization and classification of reserves, etc.

Small efficiency of manufacturing caused by manual ore selection, shows that Pobrđe deposit, particularly in the region Piskanja, can be promising for further technological exploitation over previous usual ore treatments by the methods of magnetic and electrostatic separation and subsequent thermal treatment at about 500 C. Finally, industrial testing is necessary.

  50  

Refractory concretes

Olivera Ljubić Elka d.o.o., Arandjelovac, Serbia

Refractory concretes are shaped or unshaped products, made on the basis of one or more raw materials without the use of hydraulic or other binders. They consist of a large filler and ceramic binder. Comparison of quality characteristics obtained from the same raw materials, by the method of refractory concretes production and other known ways of shaping indicate that this type of material has a higher apparent density, mechanical strength and thermal stability. It binds at low temperature, which ranking them among the materials with favorable energy balance.

The history of the development of this type of material, the principles of production, technological line, types depending on the used raw materials, with emphasis on the advantages and disadvantages of the technology, will be presented in this study.

 

 51  

The production refractory, fireproof, acid proof and ceramic product

Branimir Špiljak

Zagorka, Bedekovčina, Croatia

Our factory “Zagorka” was founded in Bedekovčina in 1889. The main reasons for starting the factory were high quality clay deposits and the railroad which had been there even in that time. The location of the factory has been in the central Zagorje in Croatia in the town Bedekovčina from its beginnings. In 1923, in one of the Zagorka's section, started the production of fireclay ovens and tiles for the stoves. The Zagorka has been working in the today's form since 1995, and we produce fireproof and acid proof materials, decorative-utility ceramics, ceramic lining for furnaces, fireplaces and tile stoves. The Zagorka has a program of producing fireproof and acid proof products, and we make materials for heavy industry (ironworks, foundries), boiler plants, thermal power plants, chemical and petrochemical plants. Producing programs is constantly enriching with new products upon customers’ requests.

  52  

Reserves of quartz sand in the Tuzla basin and its industrial application

Rešad Husagić Coal mines “Kreka”, Tuzla, Bosnia and Herzegovina

Quartz sand is a natural material that is widely used for the production of many products based on silicates. In the wider area of Kreka pool long-term research was conducted on the quantity and quality of quartz sand. Depending on the activities of individual development programs in domain of silicate complexes, partial research was performed in some locations. Raw potential of Kreka basin, according to the previous research, is estimated to be about 9.6 x 109 m3 of quartz sand.

The paper presents the possibility of application of quartz sand, found as accompanying deposits in the coal basin “Kreka” in Tuzla. Possibility of application is determined on the basis of established properties of quartz sand, either as a raw material either after a certain degree of refinement.

 

 53  

Natural resources of Gračanica area in B&H

Damir Baraković GRANEX doo, Gračanica, Bosnia and Herzegovina

Refractory and ceramic resources of Gračanica were studied in this paper. In Bosnia and Herzegovina there are significant deposits of bentonite, ceramic and brick clay, dolomite and limestone and quartz sand, quartzite, which should be more evaluated. Gračanica area is rich in various natural resources, belonging to the inner and central Dinarides. These resources in genetic terms are related to the zone of Cenozoic Neo-Alpine autonomous activating and sediment-genesis in the Neogene lakes and lagoons, or to multiphase polygenetic geodynamic movements and processes whose activity was strongest in the Miocene.

  54  

Applicability of quartz sand from the reservoir “Bukinje” near Tuzla

Hamo Isaković, Amir Baraković, Damir Baraković Faculty of Mining, Geology and Civil Engineering, Tuzla, Bosnia and Herzegovina

Quartz sand reservoir “Bukinje” is located about 2 km west from Tuzla. It is very good communicatively connected and could say, optimaly stationed in respect of gravitating market. The reservoir “Bukinje” represents the part of the upper pont, ie. the immediate floor of the first roof coal layer of crack lignite. Tectonically, the reservoir represents a small segment of the northern flank of the anticline “Ravna Trešnja”.

From the data of granulometric study it can be concluded that the fraction of fine-grained sand is dominant, with content of 78% and 23% of silty-clay fractions. The content of SiO2 as one of the most important components of the chemical composition ranges from 83-91 % while this content can be greatly increased by breeding (90-94%). The mineral composition of sand consists of quartz and feldspar (98.5%) and heavy minerals (1.5%). Certain adverse effects that occur during sand grinding to a fineness of cement, which are the consequence of the content of silty-clay part of the natural sand, can be solved by previous washing of sand.

 

 55  

Andalusite – refractory raw material: properties and application

Xiao-Yong Xiong, Aleksei Bobkov IMERYS Refractory Minerals, Paris, France

Andalusite is an alumino – silicate mineral belonging to the sillimanite family. It is

present in the form of stick in the rocks composed mainly of quartz and micas. The andalusite processing consists of its separation from the quartz and the micas. The andalusite stick's size limits the maximal size of the andalusite grain. It’s very difficult to produce the big size of pure andalusite. IMERYS has developed a complete andalusite processing technique, and successfully produced the 8 mm size andalusite product. The chemical composition of andalusite is bi-oxides of aluminum and silicon: Al2O3.SiO2 with a density 3.15. The andalusite can be directly used as raw refractory material without any thermal treatment. It will be transformed to mullite and silica glass at 1200° - 1400°C.

After mullitisation of the andalusite, the excess of SiO2 content transformed to glass is dominant inside the mullite phase. A small part of this glass is on the surface of the mullite crystal. At the high temperature, the glass softened or fused inside of the mullite can absorb the volume change of the mullite with the temperature. In this way, the mullite obtained from andalusite has the more thermal stability than the other types of mullite. This softened glass can penetrate in the possible crack fissure of transformed mullite as a welding agent to repair the damaged mullite during the use.

Andalusite has a higher refractoriness under load and a higher resistance to creep than other silico-alumina materials as bauxite, chamotte etc.

The principles of andalusite application in refractory can be summarized in three points: 1) application of mullite which is reputed as the best of the materials with a high thermal stability and a high creep resistance; the mullite based products are used specially in the equipments submit in the high temperature of long time and in the frequent thermal choc environment, 2) advantage of the slight expansion: after being fired the andalusite based products remain a slight expansion (PLC at 1500°C is +1%) useful to control the fired process of product which helps avoiding the split between the bricks, and the crack of the castable, 3) application as bonding agent: the thermal transformation of andalusite powders to mullite can form bonds between the mullite, the excess of SiO2 on the mullite surface can react with the alumina powders to form a second mullite and also a bonding system which is formed at the middle temperature range (1200°-1400°C) having very high refractoriness as mullite.

Andalusite can be applied as a product based fully on the andalusite which possesses the same characteristics as a mullite product, or as a product with andalusite powder as matrix and bauxite or corundum as grain which has the high thermal stability and high creep

  56  

resistance as mullite products, and the high abrasive resistance and high refractoriness as bauxite and corundum products.

Nowadays, the andalusite based products are widely applied in the process of iron, steel and aluminum production; in ceramic, cement and glass industry; in kiln furnaces, etc.

Effect of mechanochemical activation

Milan Petrov, Ljubiša Andić, Zoran Bartulović Institute for Technology of Nuclear Mineral Raw Materials, Belgrade, Serbia

The presented results refer to the investigation of effect the mechanical-chemical activation of flotation tailings on copper, iron and sulphur leaching degree in the sulphuric-chloride solution with the addition of H2O2 as oxidant. A sample of the Bor flotation tailings (BFT) from the old Bor flotation tailing dump consists of pyrite and tailings as the main components, and is activated in a dry process of the vibro mill with (BFT1) and without (BFT2) addition of NaOH as the chemical reagent. Using the dry magnetic separation in the high-gradient magnetic separator Sala, the samples were separated into magnetic fraction, BFT MF and BFT NMF respectively. Leaching of various treated samples showed that the highest level of copper leaching (98.7 wt %), was obtained for BFJ2 MF sample while the leaching degree of Fe and S was higher in non-magnetic, up to 92.46 wt % in BFT 1 NMF sample for Fe and 80.62 wt % for S in BFT 2 NMF sample.

 

 57  

Process industry

Application of the new lightweight aggregate based on natural pozzolanic and waste materials in concrete production

Ognjen Rudić1, Nenad Milenković1, Vilma Ducman2, Snežana Vučetić1, Jonjaua Ranogajec1

1University of Novi Sad, Faculty of Technology, Novi Sad, Serbia 2 Slovenian National Building and Civil Engineering Institute, Ljubljana, Slovenia

The properties of designed lightweight aggregates (LWA) obtained by the thermal treatment of raw composition based on natural pozzolanic material, waste glass, suitable polymer and wooden dust are presented. The production process of LWA consisted of raw material preparation, plastic shaping - extrusion, granulation and thermal treatment. The final temperature (T=1020oC) was chosen based on the appropriate mechanical and physical properties of the designed LWA pellets. Properties of raw natural pozzolanic material were examined by using DSC/TGand dilatometry, while waste glass was characterized by chemical analysis and XRF.

The particle size distribution of the LWAs was unimodal (d ≈ 5 mm). Textural and mechanical properties of LWA pellets were examined by water absorption, mercury porosimetry and compressive strength. The microstructure characteristics of LWA pellets were characterized by SEM analysis while phase composition during thermal treatment was studied by using high temperature XRD analysis. Thermal conductivity of unbound, fired LWA pellets was determined by measuring the amount of axially transferred heat in the stationary state. The obtained results show that the LWA thermal conductivity (λsr= 0,702W/mK.) is suitable for the production of structural concrete blocks with improved thermal insulating properties. Due to their high porosity and appropriate compressive strength values, the designed LWA were used in the production of concrete blocks (one third of the natural aggregate was replaced with designed LWA). Due to good thermal conductivity value (λsr= 1.31 W/mK) and compressive strength (61,57MPa after 28 days of curing), the concrete with designed LWA could be classified as a normal high strength concrete.

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Importance of determination of silicate dust in the processing of raw materials of mineral origin

Borislav Simendić, Vesna Petrović

High Technical School of Professional Studies, Novi Sad, Serbia

This paper is based on an analysis of the dust that are risky in the work environment, especially those that are present in the ceramic industry, as well as a negative perception of their impact on the health of persons exposed to it. The paper deals with the results of measuring the concentration of dust in the processing of natural stone. The aim of this work is dating with diseases that consequence of the presence of silicate dust in the working environment, and the importance of prevention of the same, namely safety at work under conditions where dust is present. It is shown that depending on the climate and working conditions in the processing of natural stone the concentration of dust in the working environment is changing. The greatest threats to the health of employees are climatic conditions with the lowest moisture content. In case of sanding granite without ventilation the maximum dust concentration of 77 mg/m3 was measured.

 

 59  

Modification of titanium substrate by alkaline and heat treatment

Bojan Jokanović1, Vukoman Jokanović2, Miroljub Vilotijević2, Rebeka Rudolf3

1SGL Carbon, Meitingen, Germany 2Vinča Institute of Nuclear Sciences, Belgrade University, Belgrade, Serbia

3University of Maribor, Faculty of Mechanical Engineering, Maribor, Slovenia

Surface modification of titanium and its alloys by formation of thin oxide layers is often necessary to enhance their biological properties. In this study, the titanium substrate was firstly alkali treated with NaOH, then it was subjected to the ionic exchange of Na+ with Ca2+

ions and finally it was thermally treatment at 700 °C. After treatment the substrate was investigated by X ray diffraction, Fourier transformed infrared spectroscopy and Auger electron spectroscopy to analyze the chemical changes and changes of Ti oxidation states, as well as the obtained phases, along the depth of the titanium oxide coatings. The morphology of the sample was analyzed by Secondary Electron Imaging, showing very interesting nano-topology consisting of interconnected pores and thin walls between them. The structure like this seems to be very suitable for further deposition of hydroxyapatite and also as a promising scaffold for cell adhesion and proliferation.  

 

 

 

 

 

 

 

 

 

 

 

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Hydroxyapatite coatings on titanium substrate obtained by high energy plasma jet deposition

Miroljub Vilotijević1, Božana Čolović1, Monika Jenko2, Vukoman Jokanović1

1 University of Belgrade, Vinča Institute of Nuclear Sciences, Belgrade, Serbia 2Institute of Metals and Technology, Ljubljana, Slovenia

Hydroxyapatite (HA) coatings were deposited on the surface of titanium substrate by the plasma jet method with high electric energy input. Prior to the deposition the substrate surface was alkali etched with NaOH and then thermally treated. The XRD spectra of the obtained coatings showed that they consisted mainly of crystalline HA and small quantities of the amorphous HA phase. The SEM analysis showed very interesting and different morphology of the HA coatings with specific micro-structural features desirable for improving the coatings’ biological performances. The AES analysis performed on various spots on the boundary of the titanium substrate and the coating showed the presence of several oxidative layers and the implantation of Ca ions inside them due to high kinetic energy of the plasma jet beam. Adhesive strength measurements showed very good results, showing values greater than 50 MPa.                                          

 

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Degradation of Reactive Blue 52 dye waste water by ClO2 in the presence of La-doped TiO2 as catalyst

Jelena Nešić1, Goran M. Roglić1, Biljana P. Dojčinović2, Milica Jović1, Predrag J. Vulić3,

Jugoslav Krstić4, Dragan D. Manojlović1 1Faculty of Chemistry, University of Belgrade, Belgrade, Serbia, 2Institute of Chemistry,

Technology and Metallurgy, Center of Chemistry, University of Belgrade, Belgrade, Serbia 3Laboratory of Crystallography, Faculty of Mining and Geology, University of Belgrade,

Belgrade, Serbia, 4Institute of Chemistry, Technology & Metallurgy, Department of Catalysis & Chemical

Engineering, University of Belgrade, Belgrade, Serbia Chlorine dioxide (ClO2) is one of the disinfectant agents used in water treatment plants as an alternative to chlorine, since unlike the chlorine, ClO2 does not form trihalomethanes. Also, photocatalysis with TiO2 as catalyst is very promising in the field of environmental remediation, especially with modified, doped TiO2 which has proven to be more efficient. Therefore, the combination of these two processes can be used and take advantage of potential synergistic effect. Experiments were conducted to investigate the removal of Reactive Blue 52 dye in order to assess the effectiveness of chlorine dioxide catalytic oxidation process under sun-like radiation. The catalyst used in this process was La-doped TiO2. La-doped TiO2 photocatalysts with different content of La (0.2, 2 and 4% (w/w)) were synthesized by the microwave-hydrothermal method and characterized by XRD, SEM and N2 physisorption at 77 K. The photocatalyst with 2% La was found to be the most efficient with ClO2. The operating parameters such as the ClO2 dosage and initial pH were evaluated. The 2% La-doped TiO2 catalyst with ClO2 showed higher efficiency than commercially available TiO2 Degussa P25 under the same conditions, therefore it can be considered as good candidate for wastewaters remediation purpose.

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Solving a technical problem in the field of medical waste incineration

Branko Pejović, Milorad Tomić, Vladan Mićić

Faculty of Technology Zvornik, University of East Sarajevo, Republic of Srpska, Bosnia and Herzegovina

In this paper, a case of incineration of two typical medical wastes in the furnace is described. Maximum amounts of both wastes that can be burned at the given conditions were determined with a large number of limitations characteristic for the observed problem. At this, the analytical geometry method was applied, where two variables that represent the mass flow of mentioned wastes were included. A mathematical model with six limitations in linear form is formed on the basis of thermodynamic relations of combustion process of waste. A presentation of method at one numerical example from practice was given, where besides required quantities of waste, working area was determined. The solution of the problem was obtained using lower heating temperature of waste. Obtained graphical solution was verified by analytical method.

 

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The future of biofuels

Vladan Mićić, Milovan Jotanović, Milorad Tomić, Branko Pejović, Zoran Petrović Faculty of Technology Zvornik, University of East Sarajevo, Republic of Srpska,

Bosnia and Herzegovina Biofuels are the future chief energy source of the world. Based on the fact that fossil fuels are non-renewable reserves, logic dictates that fossil fuels will eventually be diminished and no longer be mankind’s go to source of energy. Biofuels, on the other hand, will definitely be staying for the foreseeable future and can still continue to provide the earth and the human population with a relatively clean source of energy with several benefits such as economic benefits of providing employment and health benefits of reduced carbon emissions, leading to cleaner air. With increasing sophistication of technology and intense research and development done, one can safely infer that biofuel will become more appealing and applicable to be used on a globally commercial level. As such, biofuel is acknowledged as the Earth’s future energy source. Until such time where a newer and cleaner source of energy is discovered, scientists will definitely persist to research and enhance biofuels to make them more cost-effective, while still being environmentally friendly.

 

 

 

 

 

 

 

 

 

 

 

 

 

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Al2O3/TiO2 mixed oxide coatings: optimization of processing parameters regarding photocatalytical properties

Nenad Tadić1, Nenad Radić2, Boško Grbić2, Rastko Vasilić1, Stevan Stojadinović1

1University of Belgrade, Faculty of Physics, Belgrade, Serbia 2University of Belgrade, Institute of Chemistry, Technology, and Metallurgy, Department of

Catalysis and Chemical Engineering, Belgrade, Serbia

Influence of processing parameters on photocatalytic properties of mixed oxide Al2O3/TiO2 coatings is investigated. Mixed oxide semiconductors are prepared using plasma electrolytic oxidation of aluminum in water solution of sodium silicate, with varying concentrations of Degussa P25. Obtained oxide coatings are characterized using SEM-EDS and XRD analyses, while their photocatalytic activity is determined by degrading methyl-orange at room temperature. Optimization of processing parameters identified concentration of 2 g/L TiO2 as the most favorable for producing mixed oxide coatings with high photocatalytic activity.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Life cycles of adsorbents in the process of mineral base oil treatments

Zoran Petrović1, Pero Dugić2, Stojan Simić2, Vojislav Aleksić1, Vladan Mićić1, Mirko Petković2

1Faculty of Technology Zvornik, University of East Sarajevo, Republic of Srpska 2Oil refinery, Modriča, Republic of Srpska

Aluminosilicate clays have a structure and composition that allows a wide application in various industries. Also they have relatively good adsorption characteristics, which can be significantly improved by using a method of modification chemical structures. One of their most important applications is the adsorption process in the treatment of mineral base oils, edible oils, and in the process of environmental protection. In the production of mineral base oils commercial active clays obtained by the activation of natural aluminosilicate clay by acid are used. As result of this process there is a change in the structure, composition and their characteristics. After refining of mineral base oil by active clay obtained refined base oil as primary product and oil filter cake as by-product, which is categorized as hazardous waste. There are several methods to solve the problem of obtained waste and the priority given to those that are safe for the environment and human health. One of the acceptable ways for solving this problem is the production of ecological briquettes from the "hazardous waste" and the waste generated in treatment of wood (wood chips), which would be used as fuel for households. These investigations showed that high quality and environmentally friendly energy source for using in household can be obtained from by-product. In this paper is presented life cycles of commercial active clay in the process of treatment mineral base oils. The basic characteristics, composition and structure of commercial active clay used in the treatment of mineral base oil and oil filter cake and wood chips, as well as obtained ecological briquettes are presented. Different instrumental analytic methods (FTIR, ICP-AES, XRF), and scanning electron microscopy with EDX were used.

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Innovative company ALBOS and its main activity

Vukoman Jokanović ALBOS company, Belgrade, Serbia

Program of an innovative company ALBOS is oriented to the development of technology for various presumably refractory materials and their application in industry, with very close collaboration with other small companies - producers of such materials in Serbia.

This form of activity is very interesting as one kind of transfer of high technology in real industry and market, in this case refractory market, but in the other case it could be any other product which can be implemented in any kind of processing industry. The huge ALBOS network of professionals and specially its very high experience in various technologies is a nice example how the science can be connected with real industrial needs.

In the case of better and more transparent market approach, this kind of cooperation can be very fruitful for most of small enterprises and companies. This kind of strategy can be accepted from others companies from the region, with the aim to form one strong center over ROSOV for networking all subjects with their problems and needs.

The company ALBOS developed several products which have been applied in various large companies, producers of steel, cement or coke.

 

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Study for implementation of solar thermal systems in a local diary production capacity

Aleksandra Jakimovska1, Anka Trajkovska Petkoska1, Ilija Nasov2

1Faculty of Technology and Technical Sciences, University St. Clement of Ohrid, Bitola, R. Macedonia

2Plasma-Center for Plasma Technologies, Skopje, R. Macedonia

Solar energy as a clean, safe and endless source of energy that is available everywhere

can replace the fossil oils. Macedonia has a duty to decrease the emission of greenhouse gasses as other countries in the region according to Kyoto Protocol. This duty should not be a big problem for our country since that the potential of most of renewable energies is very high.

In this study, the example of replacing a part of energy source (electricity) with RES in a local dairy company in the region of Kichevo (Macedonia) is explained. The energy of a daily solar irradiance in this region is ~ 4100 Wh/m2/day, (according to PVGIS - Photovoltaic Geographical Information System) that is close to average value of the country. This is a big advantage of this region to use the solar energy in households as well as in industrial capacities.

Dairy industries are one of the most interesting capacities for use of renewable energy and particularly of solar energy since that they work in most cases 7 days a week and continuous use of hot water which is possible to be used from the solar thermal systems.

According to data available from a local capacity “Bistra”, Kichevo, authors attempt to present the need of solar thermal system that contains 20 solar thermal collectors (or 40 m2 collector absorbance area) and they in full will satisfy the need of hot sanitary water in this local capacity. Savings due to installation of solar system are also calculated in this study. Briefly they can be presented as: payback period of ~ 2.4 years, decrease of CO2 emission of 208 kg/annual per 1m2 collector area; savings for electricity of ~3900 Eur/annualy, etc. This is a big advantage to environment and makes the Earth safe and clean place for next generation.

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Global Ispat Coke Industry d.o.o.

Dževad Šehić RJ Koksovanje, Lukavac, Bosnia and Herzegovina

Global Ispat Coke Industry d.o.o. Lukavac (GIKIL), located in Bosnia and Herzegovina, southeastern Europe, is the company known for its high-quality products and services as well as long-standing customer relationships. The company has more then 1000 employees and the whole complex with its five operating industrial units covers an area of over million square meters.

Our range of products like metallurgical coke, anhydride of maleic acid, mineral fertilizers, power, potable water, decarbonized water and demineralized water is creating added value for our customers in a variety of industies. GIKIL´s products are highly appreciated across the world by their quality. These are the brands, built on relationship of quality, service and trust that provide the motivation for further innovation and technological excellence at GIKIL. GIKIL is the leading metallurgical coke producer in the Region and is known for its superior quality product and long-standing customer relationships.

 

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Nanotechnology

Vital pulp therapy with MTA after traumatic dental injuries

Dejan Marković 1, Ana Vuković 1, Bojana Ćetenović 2, Vukoman Jokanović3 1 Department of Pediatric and Preventive Dentistry, School of Dental Medicine, University of

Belgrade, Belgrade, Serbia 2 Department of dental Medicine, Faculty of Medical Sciences, University of Kragujevac,

Kragujevac, Serbia 3 Vinča Insitute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia

Complicated crown fractures represent 11.9-20.0 % of all traumatic injuries to permanent teeth. Pulp healing after traumatic exposure is possible, but in correlation with time interval of pulp exposure, width of exposure, stage of root development and presence of concomitant injuries. Pulp necrosis and arrested root development may influence long term prognosis of the injured tooth. Several materials have been used as pulp dressing in vital pulp therapy. To date, calcium hydroxide has been widely used and recognized as material of choice. However, in the past decades alternative material Mineral Trioxide Aggregate (MTA) has been introduced and used due to biocompatibility and low cytotoxicity. Various clinical and histological studies have demonstrated the superior therapeutic effects of MTA inducing the pulp regeneration after traumatic exposures which induces irreversible pulpitis. Also it has been confirmed that MTA enhances the proliferation of dental mesenchymal cells, but causes no cell death on the odontoblastic differentiation of pulp cells as compared with other materials. MTA provides an enhanced nonresorbable seal over the vital pulp. MTA has shown high clinical and radiographie success rates as a pulp agent in immature permanent teeth after traumatic exposures of the pulp.

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The biocompatibility investigation of MTA using animal models

Bojana Ćetenović1, Dejan Marković2, Ana Vuković2, Vukoman Jokanović3

1Department of Dental Medicine, Faculty of Medical Sciences, University of Kragujevac, Kragujevac, Serbia

2Clinic for Paediatric and Preventive Dentistry, Faculty of Dental Medicine, University of Belgrade, Belgrade, Serbia

3 Vinča Institute for Nuclear Sciences, University of Belgrade, Belgrade, Serbia Biocompatibility is defined as the material’s ability to perform desired function in the body after its application without causing unwanted response of the host tissues. The contemporary aspect of examining materials’ biocompatibility includes three levels of research: in vitro tests in laboratory conditions, in vivo tests on experimental animals and tests of application. Mineral trioxide aggregate (MTA) has appeared in the use during nineties as a material of choice for retrograde cavities, but today has a broad range of indications in dentistry. The aim of this work was to summarize the results concerning the biocompatibility of MTA using animal models. A review of the literature was performed by using electronic-searching method indexed in ScienceDirect scientific database and published from 1993 to 2013. The key words used were: MTA, biocompatibility and animal. In this period, 211 manuscripts (40 reviews and 171 research articles) concerning the biocompatibility of MTA using animal models were published. Results of numerous studies showed that subcutaneous responses to MTA ranged from moderate to severe, but decreased over time. Results of intraosseous implementation of MTA demonstrated relatively mild inflammation of bone tissue without necrosis, bone resorption, and infiltration of mononuclear inflammatory and foreign body giant cells.

 

 71  

Analysis of the glass-ionomer fissure sealant adhesion to enamel- a SEM/EDS and clinical study

Bojan Petrović1, Dejan Marković2, Tamara Perić2, Vukoman Jokanović3, Branislav Bajkin1,

Djordje Petrović1, Duška Blagojević1

1 Dental Clinic of Vojvodina, Faculty of Medicine, University of Novi Sad, Serbia

2Department of Paediatric and Preventive Dentistry, School of Dentistry, University of Belgrade, Serbia

3Institute of Nuclear Sciences “Vinča”, University of Belgrade, Belgrade, Serbia

The purpose of this study was to examine morpholological characteristics of the interface zone between glass-ionomer and the enamel surface, to evaluate the presence of the fluoride ions at the interface zone and the enamel surface and to evaluate clinical efficacy of glass-ionomer fissure sealant in 36 months observation period. Five intact third molars were used in the experimental study, and six section of each tooth were examined.

SEM/EDS analysis was performed at the material in the proximity of the interfacial zone, the interface and the enamel surface. Clinical examination comprised 60 participants and investigated parameters included: the retention rate, margin adaptation, color match, surface smoothness and caries occurrence. SEM analysis revealed the presence of thin uniform layer at the interface zone of chemical bonding between the material and the enamel surface. Morphological analysis of the interface zone between the glass-ionomer and the enamel revealed the presence of the hybrid layer of chemical bonding with specific morphological characteristics. The interface zone turned out to be about several micrometers thick, with various cracks and voids present predominantly in the material structure. Interface zone was flattened, without significant changes at the enamel surface. Enamel prisms appeared to be intact, without material tags penetrating the enamel surface. EDS analysis confirmed the presence and availability of fluoride ions at the interface zone and at the enamel surface. Regarding the retention, fissure sealant exhibited rather low complete retention rate in 3 years observation period. Partial loss of fissure sealant was the most frequent clinical finding (47%), while complete loss of fissure sealant was noticed in 12 cases. Almost 30% of the placed sealants exhibited satisfactory margin adaptation at the end of the observation period. Regarding color match and surface smoothness, glass-ionomer sealant exhibited constant characteristics throughout the investigation period. Regarding the occurrence of caries lesions, they were noticed in two cases, during the first year of observation. Caries was observed in two cases. Clinical investigation confirmed strong occlusal surface protection after glass-ionomer sealant placement. SEM analysis revealed the presence of thin uniform layer at the interface zone of chemical bonding between the material and the enamel surface. EDS analysis confirmed the presence and availability of fluoride ions at the interface zone and at the enamel surface. Clinical investigation confirmed strong occlusal surface protection after glass-ionomer sealant placement.

  72  

Cytotoxicity of the surface of titanium oxide thin films

Marko Magić1, Dejan Marković2, Vukoman Jokanović3

1Department of Oral Surgery, School of Dentistry, University of Belgrade, Belgrade, Serbia 2 Department of Pediatric and Preventive Dentistry, School of Dentistry,

University of Belgrade, Belgrade, Serbia 3Institute of Nuclear Sciences “Vinča”, University of Belgrade, Belgrade, Serbia

Titanium and its alloys are widely used as implant materials in implant dentistry and orthopedics, due to their good mechanical properties, corrosion resistance and biocompatibility. Surface modification of titanium and its alloys, by formation of thin oxide layers on their surface using various chemical methods is necessary to provide more suitable surface for cell attachment than unmodified metal titanium surface. Titanium substrate, after etching with NaOH, subsequent replacement of Na+ with Ca2+ ions, and final treatment at 600 °C was subjected to cytotoxicity testing and compared to untreated titanium substrate. Cytotoxicity was examined on the cell line L929, using MTT, LDH and cell viability assays. Qualitative verification of the results was performed using light microscopy, based on the morphological characteristics of the cells and the confluence of the cell growth in the culture. The obtained results of cytotoxicity assessment of Ti- based samples performed on L929 cell line indicates almost complete absence, or minimal cytopathic effect of Ti and Ti-Ca samples. The observed values of cell viability are below 30% and according to the analyzed Ti-based samples can be considered as noncytotoxic. Significantly lower value of LDH and consequently low percentage of cytotoxicity in the culture with the Ti-Ca samples compared to the Ti samples indicate that described modification of Ti samples would have a positive effect on reducing the already low cytotoxicity of Ti-based substrates.

 

 73  

Physicochemical and biological investigations of novel endodontic cement containing calcium silicate, calcium carbonate and radiopacifier

Djordje Antonijević1, Marija Radoičić2, Marija Prekajski2, Božana Čolović2

1Laboratory for Anthropology, Institute of Anatomy, School of Medicine, University of Belgrade, Belgrade, Serbia

2 The Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia

Calcium silicates are widely investigated for the use in dentistry but their clinical application is limited by long setting time and poor radiopacity. To overcome these disadvantages, previously synthesized calcium silicate cement was mixed with calcium carbonate to increase its setting time and ytterbium trifluoride was added as a radio pacifier. So obtained cement was investigated from the aspect of setting time, radiopacity, micromechanical properties and porosity. Phase analysis of the cement after hydration was performed by XRD and FTIR and its morphological and micromechanical characterization was done by SEM, Reference Point Indentation and micro computed tomography. To investigate its biological properties, osteoblasts and osteoclasts like cells were grown on the cement surface. Biodentine was used as a control. The results showed that addition of calcium carbonate and ytterbium trifluoride improved radiopacity and setting time of the cement. Wettability of the cement was superior to that of Biodentine, but Biodentine showed superior micromechanical properties and porosity. Osteoclasts and osteoblasts like cells adhered to the cement surface without any evident differences in their morphology. All these make this cement a promising candidate for dental application.  

 

 

 

 

 

 

 

 

 

  74  

Efficiency of carbamid and hydrogen peroxide in bleaching method in endodontic treated teeth

Nataša Knežević, Aleksandra Đeri, Željka Kojić, Renata Josipović, Irena Radman-

Kuzmanović, Valentina Veselinović

University of Banja Luka, Faculty of Medicine, Dentistry department, Banja Luka, Republic of Srpska

Carbamid and hydrogen peroxide are commonly used for dental bleaching. Hydrogen peroxide effectively denatures proteins and can penetrate through hard dental tissues. Ionization gives perhidroxide ion and superoxide ion, which leads to changes in the configuration of the elektrolyte in macromolecules. There is a change of absorption energy of macromolecules and that moves visible absorption spectrum from longer towards shorter wavelengths. That leads to creation of smaller molecules which reflect less light, and that results in achievement of dental bleaching effect. Carbamid peroxide “in situ” decomposes into urea, ammonia, carbon dioxid, water and hydrogen peroxide which is here active substance for dental bleaching.

The aim of this study was to determine the effect of bleaching of endodontic treated teeth based on the degree of change in hue, but in function of different bleaching agents.

The study was conducted on 20 extracted, endodontic treated human teeth. The teeth were bleached with internal bleaching method with 30% carbamid peroxide, and with 35% hydrogen peroxide. Agent was applied to the chamber at palatal side and cavity was closed with temporary filling for seven days. The procedure was repeated three times for every tooth. After bleaching method, teeth were restored with composite materials. The dye of tooth was determined using Vita key for dental dye before and after dental bleaching treatment and also after each session.

The teeth bleached with 35% hydrogen peroxide were discolored for one (30%) and two (70%) grades, while the teeth bleached with 30% carbamide peroxide were discolored with one (44.4%), two (33.3%) and three (22.3%) grades. The results of chi-square tests showed that there was no statistically significant difference between the solution of 30% carbamide peroxide and 35% hydrogen peroxide in efficiency of dental internal bleaching method.

Solutions of carbamid peroxide and hydrogen peroxide are equally effective in bleaching endodontic treated teeth with internal bleaching method.

 

 75  

Quality of bond strength between composite materials and teeth bleached with internal technique with 30 % solution of carbamide peroxide

Nataša Knežević, Aleksandra Đeri, Željka Kojić, Renata Josipović, Irena Radman-

Kuzmanović, Valentina Veselinović

University of Banja Luka, Faculty of Medicine, Dentistry department, Banja Luka, Republic of Srpska

Quality of bond strength between composite material and bleached tooth depends on changed micromorphological structure of enamel and dentin under the influence of bleaching. Bleaching methods can reduce adhesion of composite material for hard dental tissues, and the presence of hydrogen peroxide can affect the polymerization of composite materials.

The aim of this study was to determine the quality of bond strength between composite material and tooth bleached with internal bleaching method with 30% carbamide peroxide.

The study was conducted on 20 extracted, endodontically treated human teeth. The teeth were divided into two groups: a group of teeth bleached with internal bleaching method with 30% solution of carbimide peroxide (10 teeth) and control group (10 teeth). Agent was applied to the chamber at palatal side and cavity was closed with temporary filling for seven days. The procedure was repeated three times for every tooth. After bleaching method, preparation in class V cavities is done and teeth were restored with nanocomposite material TetricEvoCeram. The examination of mikroleakage was performed using dying in silver-nitrate, and results were read with a stereo, at incisal and gingival part of restoration. The linear dye penetration at the incisal wall of treated teeth (7.25 µm) was greater than at incisal wall of teeth from control group (5.75µm), but without statistically significant difference. Linear dye penetration at gingival wall of treated teeth (20.00 µm) was greater than at gingival wall of control group (14.25 µm). This difference was statistically significant (p<0.05).

Larger mikroleakage, or lower quality of bond strength was observed in teeth bleached with internal bleaching method with 30% carbamide peroxide than in teeth which were not treated with bleaching method.

  76  

Histological evaluation of the response of dental pulp of rats after direct pulp capping with MTA

Aleksandra Đeri, Nataša Knežević, Irena Radman-Kuzmanović, Renata Josipović

University of Banja Luka, Medical faculty, Department of dentistry, Banja Luka, Republic of Srpska

The aim of this study was to verify the efficiency of material – mineral trioxide aggregate, MTA, in direct pulp capping Wistar rats’ teeth. The study was conducted on 11 rats, specifically 22 paired first molars on which the procedure of direct pulp capping is performed. MTA is placed on 22 molars (experimental group) while 6 molars represented control group. Histological analysis was performed in two observation periods (after 14 and after 30 days) after placing MTA. Inflammatory changes in the pulp tissue were graded into 4 levels. Sections of the pulp were analyzed at the electron microscope at various magnifications.

Histological analysis of 80 sections of dental pulp at healthy rats with direct pulp capping with MTA after observation period of 14 days indicated that fibrin matrix can be seen in 61 sections in the region of contact with the pulp capping material. There were found initial signs of inflammation in 15 sections, and inflammation was expressed in 4 sections. There weren’t signs of necrosis in any sections. After observation period of 30 days, completely formed dentin bridge was observed at the site of perforation in 58 sections, initial signs of inflammation were observed in 16 sections and inflammation was observed in 6 sections.

Histological analysis of the response of the dental pulp of rats after direct pulp capping with MTA pointed to effective odontogenesis and dental bridge formation at the site of perforation.

 

 

 77  

Marginal seal evaluation of direct composite veneers

Renata Josipović, Irena Radman-Kuzmanović, Ognjenka Janković, Aleksandra Đeri, Nataša Knežević

Department of Restorative Dentistry, Dental Study Program, Faculty of Medicine, University of Banja, Republika of Srpska

Advance of new nano-composite dental materials and adhesive systems provide better quality of bond between dental hard tissue and this materials as well as possibility of minimally preparation of dental hard tissue. The aim of this study was to evaluate the marginal seal using dye method of direct composite veneers of intact and abraded anterior teeth polymerized with classical and soft start light curing technique.

The study was conducted on 40 extracted human anterior teeth. Teeth were extracted for periodontal reasons and divided into two groups: intact teeth (20) and abraded teeth (20). Ten teeth in each group were polymerized with classical and soft start technique of polymerization. Dye penetration was measured using stereo loupes with micrometer scale and six times magnification.

Linear dye penetration of direct composite veneers in intact teeth polymerized with classical technique of polymerization on the gingival wall was 2.50 µm, while on the incisal wall was 0.5 µm. Linear dye penetration in intact teeth polymerized with soft start technique of polymerization on the gingival wall was 2.25 µm, while on the incisal wall was 2.0 µm. Average dye penetration of direct composite veneers in abraded teeth polymerized with classical technique of polymerization on the gingival wall was 3.0 µm, while on the incisal wall was 1.25 µm. Linear dye penetration in abraded teeth polymerized with soft start technique of polymerization was greater on the gingival wall (3.50 µm), than on the incisal wall (3.25 µm).

After use of classical and soft start technique of polymerization direct composite veneers the lower micro crack was observed on the incisal wall, than on the gingival. The lower dye penetration was observed in the group intact teeth polymerized with classical technique of polymerization.

  78  

The importance of definitive restoration in the treatment of deep caries

Irena Radman-Kuzmanović, Aleksandra Đeri, Nataša Knežević, Renata Josipović

University of Banja Luka, Faculty of Medicine, Dental Clinic, Dentistry department, Banja Luka, Republic of Srpska

The aim of this study was to determine whether the outcome of the treatment of deep caries depends on the type of material for the definitive restoration of treated tooth. Clinical trials included 29 patients of both sexes, aged 16 to 40. Study was conducted at the Faculty of Medicine, study program of dentistry at 45 permanent morphologically different teeth with deep caries. Every tooth was radiographed before the treatment. Personal data, status of teeth, information about drugs and materials, and subjective complaints were entered in the patient medical records. After the indirect pulp capping treatment, 25 teeth were restored with composite resin Charisma and 20 teeth with composite resin Tetric Evo Ceram. At the check-ups after 3, 6, and 12 months were recorded all subjective observations of the patient, the occurrence of pain and the condition of filling, in other words, condition of composite resin.

Analyses of obtained results showed that more successful outcome of deep caries treatment was in teeth restored with a composite resin Charisma (94,1%) than with composite resin Tetric Evo Ceram (77,3%). Results of the analyses of frequency sensitivity to stimuli showed that after three months sensitivity was present in 15,6 % of cases, while in the next two observational period sensitivity was not recorded. After 3 and 6 months, there was no fracture of the crown, but after 12 months the fracture was observed in 11,1% of teeth. Teeth restored with composite resin Charisma showed slightly greater success in deep caries treatment compared to Tetric Evo Ceram. None of the material did not show any significant advantage, but confirmed that the quality of restoration is an important prerequisite for successful deep caries treatment.

 

 79  

The examination of sensitivity to corrosion of nickel-titanium and stainless steel endodontic instruments in root canal irrigating solutions

Jelena Popović1, Goran Radenković2, Jovanka Gašić1, Slavoljub Živković3, Aleksandar

Mitić1, Marija Nikolić1, Radomir Barac1 1Department of Restorative Dentistry and Endodontics, Clinic of Dentistry, Medical Faculty,

University of Niš, Niš, Serbia 2Mechanical Faculty, University of Niš, Niš, Serbia

3Department of Restorative Dentistry and Endodontics, Faculty of Dentistry, University of Belgrade, Belgrade, Serbia

The application of irrigating solutions is essential in chemomechanical treatment of root canal. However, chemical and electrochemical aggressiveness of the solutions, which directly act on instruments, may damage their surface.

The aim of this study was to investigate the sensitivity of the nickel-titanium (Ni-Ti) and stainless steel endodontic files to corrosive action of the sodium hypochlorite (NaOCl), chlorhexidine gluconate (CHX) andethylenediaminetetraacetic acid (EDTA).

Testing of sensitivity to corrosion of the instruments was performed by dynamic potentiometric method. Measurements werecarried out by means of the linear sweep technique with a sweep rate of 0,2mV/s. Anodic polarization curves were recorded and the potentials at which a sharp rise in current occurred, called the pitting potentials, were determined. The sharp rise of the potential occurs due to the beginning of the local dissolution of the metal and forming of the pits.Measurements were made in 5.25% NaOCl, 0.2% CHX and 17% EDTA.

The most intensive corrosive changes and the lowest value of pitting potential of 1.1 V showed Ni-Ti instruments immersed in 5.25% NaOCl. Slightly lower value of pitting potential of 1.3 V showed stainless steel instruments immersed in 5.25% NaOCl. Higher value of the pitting potential of 1,7 V and lower corrosive surface changes showed stainless steel instruments immersed in 0.2% CHX, whereas nickel-titanium instruments immersed in 0.2% CHX showed the pitting potential of 2 V.The corrosion was not observed in both types of instruments after immersion in 17% EDTA.

The useof 5.25% NaOCl and 0.2% CHX may cause severe surface corrosion of Ni-Ti and stainless steel endodontic files. The use of EDTA did not cause corrosion of the surface of both types of instruments.  

  80  

SEM examination of the surface corrosion of endodontic filers after immersion in irrigating solutions

Jelena Popović1, Goran Radenković2, Jovanka Gašić1, Slavoljub Živković3, Aleksandar

Mitić1, Marija Nikolić1, Radomir Barac1 1Department of Restorative Dentistry and Endodontics, Clinic of Dentistry, Medical Faculty,

University of Niš, Niš, Serbia 2Mechanical Faculty, University of Niš, Niš, Serbia

3Department of Restorative Dentistry and Endodontics, Faculty of Dentistry, University of Belgrade, Belgrade, Serbia

Chemomechanial canal preparation during root canal treatment includes procedures of cleaning and shaping with endodontic instruments and irrigation solutions. The functions of the irrigants are to act as lubricants, to dissolve tissue and remove debris, and to promote root canal sterility. However, the chemical effects of the irrigating solutions may damage the instruments surface and hinder their performance.

The purpose of this study was to evaluate surface of the endodontic instruments after immersion in different irrigating solutions using scanning electron microscope (SEM).

The study included nickel-titanium and stainles steel hand endodontic files. After immersion in three most used irrigating solutions (5.25% NaOCl, 0.2% chlorhexidine gluconate (CHX) and 17% EDTA), the instruments were subjected to SEM examination.

SEM examination of the samples revealed general severe corrosion in form of spots, pits and cracks on the instrument surface after immersion in 5.25% NaOCl. Corrosion had also occured in local regions on the surface of the instruments after immersion in 0.2% CHX. SEM analysis revealed no corroded areas on the surface of the instruments treated with 17% EDTA, and those instruments were similar to control samples.

The useof 5.25% NaOCl and 0.2% CHX may cause intensive surface corrosion of endodontic files. The use of 17% EDTA did not cause corrosion of the instrument surface.

 

 81  

Modified porous apatite biomaterials: An in vivo biocompatibility study

Milena Aleksić1, Andrea Žabar Popović1, Perica Vasiljević1, Ljubiša Đorđević1, Stevo Najman2, Vukoman Jokanović3

1Department of Biology and Ecology, Faculty of Science and Mathematics, University of Niš, Niš, Serbia

2 Institute of Biomedical Research, Medical Faculty, University of Niš, Nis, Serbia 3 Vinča Institute of Nuclear Sciences, Laboratory of Radiation Physics and Chemistry,

Belgrade, Serbia

During recent years a number of different synthetic biomaterials for the regeneration and repair of tissues, particularly bone tissue, have been developed. Biomaterials based on calcium phospate (apatite) were shown to be the most effective in bone tissue reparation. The aim of the study was to examine the biocompatibility of two materials based on porous apatite: porous apatite thin alginate film (PA + A) and porous apatite with a thin film of polylactide co-glycolide (PA + PLLA) in vivo. Both biomaterials were implanted in BALB / c mice subcutaneously in the interscapular region and intraperitoneally. Biomaterials were divided into two test groups. The first group consisted of materials implanted alone, and second group contained tested materials with blood plasma. After two week period, the mice were sacrificed and implants with surrounding tissue were surgically removed. The tissues were fixed in 10% neutral formalin, decalcified in formic acid and further processed by routine histological protocol. Histological sections were visualized using two different staining techniques: Harris haematoxylin / eosin and Masson Trichrome. Obtained sections were observed using light microscopy. Histopathological analysis revealed the presence of giant multinuclear cells and moderate production of collagen. Mild resorption of biomaterials was observed. All this findings indicated the presence of moderate inflammatory response. At the end of the two week period we did not notice a significant difference between the biomaterials which were implanted with blood plasma and biomaterials without blood plasma.

  82  

Biocompatible Materials – Metals

Aleš Stambolić, Monika Jenko IMT, Ljubljana, Slovenia

The biomaterials in medicine were used already 4000 years ago unaware of their properties. It is now only 150 years that we are researching the interactions between the host tissue and materials. The main groups of biomaterials are metals, ceramics and polymers. Metals have excellent strength and are used as load-bearing materials; ceramics are hard but brittle and are often used in dentistry, while polymers are quite soft composite materials. Problems with biomaterials appear in aggressive environments and the consequences are corrosion, wear, fatigue and release of toxic ions into the human body. To reduce the failure of a biomaterial, a passive layer should be deposited on its surface. This is achieved by oxidation process where the oxide layer forms on the surface and protects the bulk material from further degradation. Oxidation kinetics of metals obeys three different laws depending on the temperature of oxidation: linear, parabolic and logarithmic law. Logarithmic law usually represents oxidation in thin layer regime at low temperatures. In parabolic law, the oxide growth occurs with a continuing decreasing oxidation rate. Linear law appears when rate of oxidation remains constant with time.

 

 

 

 

 

 

 

 

 

 

 

 

 83  

Heavy metals nickel and cobalt induce epileptiform activity in leech Retzius neurons

Marija Stanojević1, Srđan Lopičić1, Svetolik Spasić1, Isidora Aleksić1, Milica Prostran2,

Vladimir Nedeljkov1

1Institute for Pathological Physiology “Ljubodrag Buba Mihailović'', Faculty of Medicine, University of Belgrade, Serbia

2Institute for Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, Serbia

Heavy metals nickel and cobalt are environmental pollutants, but human exposure to them is particularly high when it is occupational. Nickel and cobalt toxicity can produce a variety of adverse effects on human health, including epileptic seizures.

The object of the present study was to examine the effects of heavy metals nickel and cobalt on intracellularly recorded activity of Retzius neurons of the leech Haemopis sanguisuga.

Experiments were performed in two separate trials. The addition of 3 mM NiCl2 or 3 mM CoSO4 into the superfusing saline induced epileptiform activity. Epileptiform activity was characterized by the generation of membrane potential oscillations in a form of paroxysmal depolarization shifts (PDSs). Frequency, duration and amplitude of PDSs were measured, as well as the duration of PDS intervals. A PDS interval was defined as time period from the beginig of one PDS to the beginning of the next one. The intensity of PDS activity was calculated as a percentage of PDS duration within its belonging PDS interval. All data are presented as average±SEM.

Both Ni2+ and Co2+ induced epileptiform activity in leech Retzius neurons. Epileptiform activity consisted of repetitive PDSs. Nickel-induced PDSs had an average frequency of 5.53±0.39 min-1, average duration of 5.38±0.26 s, and an average amplitude of 12.90±0.77 mV. Average intensity of Ni2+-induced PDS activity was 48.20±1.54 % (n=10). Cobalt-induced PDSs had an average frequency of 3.61±0.35 min-1, average duration of 3.71±0.34 s, and an average amplitude of 6.14±1.07 mV. Average intensity of Co2+-induced PDS activity was 22.11±2.47 % (n=6). Nickel and cobalt disturb spontaneous electrical activity of leech Retzius neurons, inducing epileptiform activity. As a convulsant nickel proves to be more potent than cobalt on our cell epilepsy model.

  84  

Application of nanotechnology in medicine

Dragana Jordanov1, Branislav Milovanović2, Branko Matović1, Milena Rosić1, 1Institute of Nuclear Sciences Vinča, University of Belgrade, Belgrade, Serbia

2University Medical Center B. Kosa, Neurocardiological laboratory, Medical faculty, University of Belgrade

X-difractometry (XRD) is widely used in material science like the one of the most sensitive and foolproof method in nanotechnology. But XRD also have numerous applications in medicine, optics, electronics, chemistry and biology. In this work the crystal structure of industrial produced drug Midodrine (Gutron) has been investigated by X-ray methods and comparing with placebo forms obtained from sucrose. Properties such as lattice parameters, chemical composition and crystal phase of that samples were monitored by X-ray powder diffraction on a Siemens D-500 XRPD difractometer with Cu Kα1,2 radiation, at room temperature. The measurements were performed in the range 2-600 2θ in a continuous scan mode with a step width of 0.020 and 0.5 s/step. The results were analysed using the software package Powder Cell. The difference in structure between sucrose and placebo forms was noticed.  

 

 85  

Calcium oxalates urolithiasis - assessment of some renal cell injury

Vatroslav Šerić1,2, Vesna Babić-Ivančić2,3 1 Clinical Hospital Center Osijek, Division of Clinical Laboratory Diagnostics,

Osijek, Croatia 2Faculty of Medicine Osijek, Osijek, Croatia 3Ruđer Bošković Institute, Zagreb, Croatia

Urolithiasis is a chronic, relapsing disease in which mineral aggregates are formed in the urinary tract. It represents one of the pathologic biomineralisation forms. However, despite that many intensive researches have been conducted, all mechanisms of the formation and growth of the stones have not yet been discovered due to its complex and multifactorial process. An important factor in the formation of the stones is retention of formed crystals in the urinary tract. Renal cells damage induced by oxidative stress due to the presence of a crystallization promoter in higher concentrations in the urinary tract and inflammation resulting from greater predisposition for crystal-cell interactions, as shown by sensitive biomarkers of renal damage such as L-FABP, n-GAL, cystatin C. In this paper the degree of damage to the epithelial cells of renal tubules caused by toxic effects of hyperoxaluria in patients with calcium urolithiasis using the some biomarkers of kidney damage as a new way of assessing the propensity to formation urinary and / or kidney stones. Results metabolic parameters of urolithiasis in the first morning urine of the patients showed higher values of promoting factors for calcium lithiasis, index risk, as well as increased levels of biomarkers of values obtained for the same parameters in controls. In conclusion it can be said that it is possible, based on the assessment of the degree of renal tubular cells with the investigated biomarkers, to predict the possible retention of the generated crystals in the urinary tract of people with calcium urolithiasis

  86  

The encrustates on urological double J stent - physco-chemical analyses

Hrvoje Kuveždić1, Jasminka Kontrec2, Dalibor Šimunović1, Vesna Babić-Ivančić2,3 1Clinical Hospital Center Osijek, Urology Clinic, Osijek, Croatia

2Ruđer Bošković Institute, Zagreb, Croatia 3Faculty of Medicine Osijek, Osijek, Croatia

In humans, one of the pathological forms of biomineralization in the body is a process in which the complex chemical systems, such as the urine, precipitated inorganic salts such as the kidney and / or urinary stones of different composition. This process is influenced by physico-chemical, genetic, endocrine, anatomic, climate, inflammatory and others factors. The disease is defined as urolithiasis and is still a serious health, social and sociological problem.

Double J stent has been established as very valuable medical tool in treatment of numerous urological conditions. As such it has its advantages and drawbacks. The complications of double J stent are well documented and in the most cases are not life-treating. The most common “technical” complication is formation of stent encrustations which render stent nonfunctional. The stent encrustation is most easily prevented by stent replacement. The etiological factors of the stent encrustation, besides biofilm formation and inflammation, are not well documented. The aim of this research was to analyze selected etiological factors and their role in the stent encrustation. The secondary objective was to test the hypothesis that chemical composition of the encrustate must be same as of primary stone, with premise that alkali urine will favor the phosphate stones. Deposits on JJ stent removed from the urinary tract in selected groups of patients were characterized by thermal FT-IR spectroscopic analysis and gravimetric analysis (TG) . The composition of the encrustates on the urological stents were compared with the composition of urinary stoneand it is shown that they are not consistent. In conclusion it can be said that some of the parameters were not significantly different in patients with and without encrustates. The most common encrustate component is apatite, then struvite, and least common are calcium oxalate encrustates. The compositions of the encrustates were not always identical at different levels.

 

 87  

Synthesis and characterization of multiferroic BiFeO3 powders fabricated by hydrothermal and mechanochemical method

Maria Čebela1, Radmila Hercigonja2, Svetlana Ilić1, Miljana Mirković1, Mia Omerašević1,

Branko Matović1

1Laboratory of Materials Sciences, Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia

2Faculty of Physical Chemistry, University of Belgrade, Belgrade, Serbia

Bismuth ferrite (BiFeO3) is one of the most investigated single-phase multiferroic materials. BiFeO3 nanopowder have been successfully synthesized by the hydrothermal and solid state synthesis methods. We analyzed the particles size using granulometric analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The phase composition of the sintered samples was determined by x-ray diffraction (XRD) analysis. It revealed that synthesized material crystallize in space group R3c with cell parameters a = b = 5.5780(10) Å and c = 13,863(3) Å. The powders behavior was characterized by TG/DTA and Heating stage microscope. The magnetic behavior of synthesized material is done by means of SQUID device and using a vibrating sample magnetometer (VSM).

  88  

Thermal transformation of Cs-Exchanged zeolite

Mia Omerašević1, Bojana Nedić Vasiljević2, Svetlana Ilić1, Maria Čebela1, Miljana Mirković1, Ana Radosavljević-Mihajlović1, Branko Matović1

1Laboratory for Material Science, Institute of Nuclear Sciences “Vinča”, University of Belgrade, Belgrade, Serbia

2Faculty of Physical Chemistry, University of Belgrade, Belgrade, Serbia    Cesium aluminosilicate phases are of great interest as possible hosts for 137Cs

immobilization in radioactive waste management. Cs+ exchanged forms of two synthetic LTA zeolites (4A and 5A) were prepared by ion exchange procedure. Synthesized samples were thermally treated in temperature range of 600ºC-1400ºC. High temperature phase transformations of Cs+ exchanged zeolites (Cs-LTA) were investigated. Based on data obtained by FTIR, TG-DTA, SEM/EDS and XRPD analysis of the samples, it was concluded that above 1000 ºC Cs-LTA (4A and 5A) frameworks recrystallized into a pollucite phase.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 89  

Synthesis of Monetite (CaHPO4) by mechanochemical treatment of Brushite (CaHPO4·2H2O)

Miljana Mirković1, Anja Došen1, Biljana Babić1, Maria Čebela1, Mia Omerašević1,

Branko Matović1, Aleksandra Rosić2

1Laboratory of Materials Sciences, Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia

2Department of mineralogy and crystallography, Faculty of Mining and Geology, University of Belgrade, Belgrade, Serbia

In the field of biology and medicine different types of calcium phosphates materials (CaP) play a very significant role. They can be found in a human body as one of the crystalline components of human enamel, dentine, cementum and bones and as a pathological product – phosphatic renal stones. Calcium phosphates such as brushite (CaHPO4·2H2O) and monetite (CaHPO4) are of great scientific interest in the field of biomaterials. Main objective of this study is a synthesis of monetite by mechanochemical treatment of synthesized brushite. When brushite loses its structural water it transforms to monetite. Pure synthesized brushite nanomaterial was obtained, and the particle size was modified by grinding in the vibrating mill. The sample was ground five times for 2.5 minutes and analyzed by XRD between grinding. Crystallite sizes were determined from the XRD patterns using Scherer equation. After about 5min of grinding an increase in temperature causes a phase transformation from brushite to monetite, after 12.5 min of grinding we get monetite material. BET method indicates that synthesized brushite is micro porous. After 5 minutes of milling brushite is mezzo porous, these results were confirmed by SEM images. Mechanochemical treatment and phase transformation of brushite to monetite is cost-effective and much faster than the standard methods for synthesize monetite.      

 

 

 

 

 

 

 

  90  

Young’s modulus evaluation and thermal shock behavior of a porous SiC/cordierite composite materials

Milica Pošarac-Marković1, Jelena Majstorović2, Aleksandar Devečerski1, Branko Matović1,

Tatjana Volkov –Husović3

1University of Belgrade, Vinča Institute of Nuclear Sciences, Belgrade, Serbia 2 University of Belgrade, Faculty of Mining and Geology, Belgrade, Serbia

3 University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia

Porous SiC/Cordierite Composit samples with graphite content (10%) were synthesized. Evaluation of Young modulus of elasticity and thermal shock behavior of these samples will be presented. Thermal shock behavior will be monitored using water quench test, and non destructive methods such are UPVT and image analysis will also be used for accompaniment the level of destruction of the samples during water quench test. Based on the level of destruction graphical modeling of critical number of cycles will be given. This approach will be implemented on discussion of the influence of the graphite content on thermal stability behavior of the samples.

 

 91  

Dopant effect of iron on the formation of sol-gel derived mullite

Svetlana Ilić, Slavica Zec, Vesna Maksimović, Maria Čebela, Mia Omerašević, Aleksandra Šaponjić, Branko Matović

University of Belgrade - Institute of Nuclear Sciences “Vinča”, Materials Sci. Lab., Belgrade, Serbia

Precursor powders of pure and iron doped mullite were prepared using sol-gel combustion method. Firstly, the solutions of the synthesized iron doped mullites (composition 6-15 wt % of Fe2O3) were obtained by dissolving of Al(III) nitrate, Fe(III) nitrate and TEOS in ethanol. Afterwards, water and urea were added. The prepared solutions were heated on a hot plate to evaporate solvents and obtain gels that were further heated to initiate combustion process. During the heating on a hot plate nitrates have been decomposed emitting brown gases. As-prepared ashes were heat treated at 800 °C for 4 h to remove the remaining organic residues and retained nitrogen. Sintering of uniaxially pressed pellets (8 mm, 135 MPa) was performed at 1550 °C for 4 h. XRD analysis confirmed that all as-synthesized powders were amorphous while a single mullite phase appeared in the sintered samples. Also, the lattice parameters of doped mullites increase with increasing iron content due to replacement of Al3+ - by larger Fe3+ -ions in mullite lattice. TGA/DSC analysis showed lowering of crystallization temperature of iron doped mullite with increasing iron content. The SEM micrographs of the sintered samples reveal elongated lath-like mullite grains that enlarge and become better packed with enriching of the reaction mixtures by iron. Densities of sintered samples have also increased.

 

 

 

 

 

 

 

 

 

 

  92  

Sintering and magnetic behavior of Ca1-xGdxMnO3 (x=0.05, 0.1, 0.15, 0.2) nanopowders

Milena Rosić1, Ljiljana Kljaljević1, Dragana Jordanov1, Milovan Stoiljković1,

Vladan Kusigerski2, Vojislav Spasojević2, Branko Matović1 1Laboratory for Material Science, Institute of Nuclear Sciences „Vinča“, University of

Belgrade, Belgrade, Serbia 2Laboratory for Physical Chemistry, Institute of Nuclear Sciences „Vinča“, University of

Belgrade, Belgrade, Serbia 3Condensed Matter Physics Laboratory, Institute of Nuclear Sciences “Vinča“, University of

Belgrade, Belgrade, Serbia

The synthesis, sintering temperatures and magnetic properties of Ca1-xGdxMnO3 (x=0.05; 0.1; 0.15; 0.2) perovskite has been investigated. Powders were prepared using a modified glycine nitrate procedure. Sintering of the green bodies was carried out by conventional sintering (CS) method with a special emphasis on the effects of sintering temperature (1300–1400 oC). CS was applied on nanocrystalline system of Ca1-xGdxMnO3 (x=0.05; 0.1; 0.15; 0.2) to control the accelerated grain growth and high-density occurring during the final stage of sintering. All samples where characterized by ICP, XRD, FTIR, SEM, EDS and SQUID magnetometry. Magnetic measurements show the existence of a phase transition antiferromagnetic - paramagnetics at a temperature TN = 105 K. The value of the effective magnetic moment of the manganese ions is between the values of Mn3+ and Mn4+ ions, which show their mixed valence of the tested compound. Properties of the synthesized powders together with sintering and magnetic tests are discussed.

 

 93  

Synthesis and Characterization of Sphene Based Ceramics

Jelena Pantić, Jelena Luković, Maria Čebela, Tamara Minović, Miljana Mirković, Svetlana Ilić, Milena Rosić

Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia

Sphene (CaTiSiO5), a calcium titanosilicate ceramic has been prepared from a powder mixture of CaCO3, TiO2 and SiO2 using vibro-milling for homogenization and activation of precursors. Also, mechanical activation of precursors has been used for the preparation of Cr-doped sphene ceramic pigments (CaTi1−yCrySiO5). The mechanochemical process initially yielded amorphous powders, which on further calcination, crystallized to yield sphene ceramic. Low and high pressure sphene ceramics are obtained by pressureless and high pressure - high temperature synthesis process (at 4 GPa, 1200°C). The resulting room (P21/a) temperature phase is thermally unstable and it transforms to high (A2/a) pressure-temperature phase.

The evolution of the phase composition with thermal treatment was investigated by X-ray powder diffraction (XRPD). Powder morphology and particle size distribution were analyzed by scanning electron microscopy (SEM) and laser diffraction, respectively. Rietveld refinement was employed to get the structural information of the synthesized powder. Densification and microstructure evolution was determined by means of density and scanning electron microscopy (SEM). UV/Vis reflectance spectra are used to determinate the behavior of the chromium ion. The color efficiency of pigments was evaluated by colorimetric analysis (CIE L * a * b system). Raman and IC measurements were performed to verify phase transition.

  94  

Synthesis and characterization of Ce1-xBixO2-δ solid solution for application in solid oxide fuel cells

Marija Prekajski1, Jelena Pantić1, Jelena Luković1, Marija Stojmenović1,

Goran Branković2, Branko Matović1 1Institute of Nuclear Sciences ”Vinča”, University of Belgrade, Belgrade, Serbia

2Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia

CeO2 system doped with Bi3+ can be very interesting for application in SOFC’s due to the

high ion conductivity of CeO2 and Bi2O3 phases. Exactly that was a motivation for synthesis, characterization and study of sintering properties and ionic conductivity on this solid solution. Solid solution Ce1-xBixO2-δ nanopowders with the composition of x = 0.1 - 0.5 were synthesized by using Self Propagating Room Temperature procedure (SPRT). The results obtained by XRPD show that synthesized samples were single-phase solid solution at room temperature. Powders were densified by using Conventional (CS) and Microwave (MS) Sintering techniques at different temperatures, in an air atmosphere for 1 h. Complex impedance method measurements were carried out on sintered samples. The highest conductivity was obtained for the ceramic composition Ce0.80Bi0.20O2-δ sintered by microwave technique at 700 °C. Ionic conductivity measurement showed that conductivity increased dramatically with increasing temperature as well as with Bi3+ concentration. It seems that Ce1-

xBixO2-δ solid solution is promising material for application in IT-SOFC’s.    

 

 

 

 

 

 

 

 

 

 

 

 

 95  

Simple tungsten carbide synthesis from tungsten(VI) oxide

Jelena Luković1, Biljana Babić1, Marija Prekajski1, Jelena Pantić1, Marija Stojmenović1, Igor Pašti2, Branko Matović1

1University of Belgrade, Institute of Nuclear Sciences “Vinča”, Belgrade, Serbia 2University of Belgrade, Faculty of Physical Chemistry, Belgrade, Serbia

Tungsten carbide powder has been prepared by straightforward method. Tungsten (VI) oxide was placed on the activated carbon cloth that was in a carrier and put into the furnace. Furnace, through which hydrogen flowed, was heated up to 750 °C. Than the flowing gas was changed to acetylene, and temperature was further raised to 900 °C. The sample was at this temperature for one hour before the furnace was cooled to the room temperature. Obtained powder was tungsten carbide.

Composition of the powder was determined by X-ray powder diffraction (XRPD). Specific surface area and texture of obtained powder were examined by Brunauer–Emmett–Teller (BET) method. Capacitive and electrocatalytic properties of the sample in alkaline media were done in a conventional one-compartment three-electrode electrochemical cell. The GAMRY PCI4 / 750 potentiostats / galvanostat was used in the voltammetric studies.

 

 

 

 

 

 

 

 

 

 

 

 

  96  

Effect of UV/ozone treatment on the surface energy and nanoscale topography of gold implanted polyethylene

Miloš Nenadović, Danilo Kisić, Danka Stojanović, Zlatko Rakočević

University of Belgrade, Vinča Institute of Nuclear Sciences, Belgrade, Serbia The effect of ultraviolet (UV) ozone treatment on the surface energy and nanoscale

topography of gold implanted high density polyethylene (HDPE) was investigated, by atomic force microscopy (AFM) and contact angle measurement. HDPE samples were modified by the implantation of gold ions at a dose of 5×1015 ions/cm2, using energies of 50, 100, 150, and 200 keV, and subsequently treated with UV/ozone. Surface energy of the samples was calculated from contact angle measurements, using Owens-Wendt model. After gold implantation surface energy decreases, with higher percentage of polar component, while after UV/Ozone treatment surface energy increases, and polar component percentage increases to above 95 %. AFM showed that the surface is significantly damaged after implantation, while UV/ozone treatment caused significant changes visible by formation of small hemispherical structures on the surface.

 

 97  

Structural, optical and electrical properties of argon implanted TiN thin films

Maja Popović, Mirjana Novaković, Nataša Bibić

University of Belgrade, Vinča Institute of Nuclear Sciences, Belgrade, Serbia

Modification in structural, optical and electrical properties of titanium nitride (TiN) thin films induced by argon ion irradiation and thermal annealings were studied using various experimental techniques. TiN thin films deposited by dc reactive sputtering on Si substrate were implanted with argon ions at 200 keV. As-implanted samples were annealed before or after ion irradiation at 600 oC and 700 oC, respectively. Rutherford backscattering spectrometry, X-ray diffraction, cross-sectional (high-resolution) transmission electron microscopy, spectroscopic ellipsometry and electrical measurements were carried out in order to study structural, optical and electrical properties of TiN/Si samples. After irradiation with 200 keV Ar ions the columnar microstructure of TiN was changed and the presence of smaller crystalline grains were observed. Partial loss of columnar structure observed in implanted samples was completely recovered after annealing at 700 oC. Observed changes in microstructure induced by ion irradiation and annealings were correlated with the variation in optical parameters obtained by spectroscopic ellipsometry. It was found that both refractive index and extinction coefficient are strongly dependent on the defects concentration and size of the crystalline grains in TiN layers.

  98  

Xenon-ion-induced mixing of Co/Si bilayers

Mirjana Novaković1, Marija Popović1, Kun Zhang2, Nataša Bibić1 1University of Belgrade, Vinča Institute of Nuclear Sciences, Belgrade, Serbia

2II. Physikalisches Institut, Georg-August-Universität Göttingen, Göttingen, Germany

Studies on ion-irradiated transition-metal/silicon bilayers demonstrate that interface mixing depend sensitively on the ion and film parameters, including the structure of the metal/Si interface. Thin Co layers e-gun evaporated to a thickness of 50 nm on Si (100) wafers were bombarded at room temperature with 400-keV Xe+ ions at fluences of up to 3 ×1016 ions/cm2. We used either crystalline or pre-amorphized Si wafers, the latter ones prepared by 1.0-keV Ar-ion implantation. Changes of the bilayer structures induced by ion irradiation were investigated with Rutherford backscattering spectrometry and high-resolution transmission electron microscopy. It was found that the mixing rate for the Co/crystalline-Si couples, Δσ2/Φ = 3.0(4) nm4, is higher than the value expected for ballistic mixing and about half the value typical for spike mixing. Mixing of layers with pre-amorphized Si is much weaker relative to crystalline Si wafers, contrary to previous results obtained for Fe/Si bilayers.

 

 99  

Properties of the nanostructured nickel thin films deposited by GLAD technique

Jelena Potočnik1, Miloš Nenadović1, Bojan Jokić2, Zlatko Rakočević1

1University of Belgrade, INS Vinča, Laboratory of Atomic Physics, Belgrade, Serbia 1University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia

In this study, structures of the nickel thin films have been obtained using Glancing Angle Deposition (GLAD) technique. Glass substrates were positioned 75 degrees with respect to the substrate normal. The substrates were rotated with a suitable constant speed followed by intervals without rotation. The durations of rotations were 10 minutes, 30 minutes and 1 hour, for the different samples, while the total time of deposition was kept constant. During the deposition time of 1 hour 30 minutes nickel thin films with a thicknesses of 260 nm, 230 nm and 210 nm were obtained. The deposited nickel thin films were characterized by Scanning Electron Microscopy and Atomic Force Microscopy. Magnetic properties of the thin films were observed by Magneto–Optical Kerr Effect Microscope. The values of the specific resistivity of the samples were found using Four-Point Probe method.  

 

 

 

 

 

 

 

 

 

 

 

 

 

  100  

Interactions in mixtures of sodium bis (2-ethylhexyl) sulfosuccinate (AOT) and ionic liquid

Sanja Novak1, Sara Morasi-Piperčić2, Sandro Makarić2, Ines Primožič2, Darija Jurašin3 1Department of Physical Chemistry, Faculty of Science, University of Zagreb, Croatia 2Department of Organic Chemistry, Faculty of Science, University of Zagreb, Croatia

3Division of Physical Chemistry, Ruđer Bošković Institute, Zagreb, Croatia

Surfactants (shorten for surface-active agents) are organic compounds containing in one molecule both lyophobic (hydrophobic) and lyophilic (hydrophilic) parts. Due to such amphiphilic structure surfactants exhibit specific properties in solutions, as well as in solid state. Mixtures of two or more different of surfactants often show a synergistic effect i.e., the interfacial properties of the mixture are more pronounced than those of the individual components themselves. As a result, in many industrial products and processes, mixtures of different types of surfactants, rather than individual materials, are used. Aqueous catanionic surfactant mixtures, mixtures of opposite charge surfactants, offer numerous possibilities in mediating molecular self-assembly by varying the molar ratio and/or concentration of oppositely charged surfactants.Interactions in aqueous mixtures of the cationic surfactant (1-dodecyl-3-methylimidazolium bromide, [C12mim]Br) and anionic surfactant (sodium bis (2-ethylhexyl) sulfosuccinate, AOT) have been investigated by surface tension, conductivity, microelectrophoretic and light scattering measurements as well as by optical microscopy. Due to its molecular structure AOT shows a tendency to form interfaces with minimal curvatures, such as vesicles and flexible bilayers even in dilute aqueous solutions.2 [C12mim]Br as ionic liquid (IL) also exhibits unique physco-chemical properties. The term ionic liquid (IL) refers to a class of substance formed by a large organic cation and either a small anion, such as Br−, or relatively large one, such as [(CF3SO2)N2]− with melting points under 100 oC, often even lower than room temperature. In the last decade ILs have attracted increasing interest in numerous scientific areas such as chemistry, physics, engineering, material science, energy and fuels, among others. Investigated mixtures display interesting interfacial and phase behavior properties; i.e. strong synergistic effects were observed for both their interfacial and bulk properties. Competition between various molecular interactions (hydrophobic, electrostatic, van der Waals, hydration forces, etc.) results in the formation of mixed monolayer at the air/solution interface and variety of microstructures and liquid crystall phases in bulk phase. Phase behaviour observed in the investigated mixtures is not typical for the catanionic mixtures. In equimolar mixtures gel-like mesophase appears instead of a solid crystalline precipitate. Also, mixed micelles do not form even in the large excess of one of the surfactants. However, small and large vesicles are found in a broad concentration range. Observed behaviour is consequence of chain length asymmetry and great solubility mismatch between surfactants in mixtures.  

 

 101  

Stability of titanate nanowires in aqueous medium

Natali Nakić1, Darija Jurašin2, Maja Dutour Sikirić2, Atiđa Selmani1

1Department of Physical Chemistry, Faculty of Science, University of Zagreb 2Division of Physical Chemistry, Ruđer Bošković Institute, Zagreb, Croatia

Recently, nanostructural TiO2 materials of different morphologies (nanoparticles, nanotubes, nanosheets, nanowires) have been synthesized. These materials attract considerable interest due to their unique phyisico-chemical properties and numerous possible applications. However, the success of their application, as well as possible toxicity and environmental impact, depend on particle size and stability in the medium of interest. Stability of nanoparticles is affected by concentration of the particles themselves, composition (presence of the ions and organic material), pH and ionic strength of the medium.   The influence of the medium of different ionic strength and pH (Mili Q water and phosphate buffer saline, PBS) on the satbility of titanate nanowires has been investigated. Titanate nanowires have been synthetised by hidrothermal method. Structure and composition of nanowires have been determnined by powder X-ray diffraction, infrared and Raman spectroscopy. Morphology of nanowires has been visualised by scanning electron microscopy and specific surface has been determined by BET. Nanowires stability in water and PBS has been monitored for 24 hours by dynamic light scattering. The influence of nanowires concentration has also been determined. Size of titanate nanowires in both media is decresing woth the time. No significant difference in stability of nanowires between investigated media was observed.

  102  

Nanostructured carbon materials in electroanalysis – proof of concept for sensing of bismuth ion

Nevena Markičević, Biljana Šljukić, Radmila Hercigonja, Gordana Ćirić-Marjanović

University of Belgrade, Faculty of Physical Chemistry, Belgrade, Serbia

Different carbon electrodes were explored for application in electroanalysis, namely for sensing of bismuth ion as model analyte. The carbon materials tested included glassy carbon, edge and basal plane pyrolytic graphite, as well as prepared carbonized nanostructured polyaniline. Polyaniline was synthesized by the oxidative polymerization of aniline in the presence of 3,5-dinitrosalicylic acid, and then carbonized in nitrogen atmosphere by means of gradual heating up to 800 °C.

Bismuth ion was chosen as model analyte as protocol for its detection and quantifications is still to be determined. Herein, anodic stripping voltammetry was used with optimization of several parameters such as deposition potential and time. Electrode based on carbonized polyaniline showed the highest catalytic activity for bismuth ion sensing in terms of the highest current densities recorded, both in a laboratory and in real sample.

 

 103  

Synthesis and characterization of barium titanate thin films obtained by wet chemical deposition technique

Branimir Bajac1, Jelena Vukmirović1, Đorđije Tripković1, Elvira Đurđić2, Željka Cvejić2,

Srđan Rakić2, Vladimir Srdić1 1Faculty of Technology, Department of Materials Engineering, University of Novi Sad,

Novi Sad, Serbia 2Faculty of Sciences, Department of Physics, University of Novi Sad, Novi Sad, Serbia

In recent years, interest in electroceramic materials has grown rapidly. The application of dielectric thin ceramic films for production of specific microchip components, such as capacitors and sensors, have reduced the size of those components to nanometer scale. The most research have been performed on BaTiO3, because it possesses high dielectric constant at room temperature and good electrical polarization. This research presents process of preparation of BaTiO3 thin films obtained by spin coating deposition technique. Particle size and viscosity of precursor sols have been characterized by DLS and rotational viscometer, respectively. After the thermal treatment at 750˚C for 30 minutes, morphology and phase composition of obtained thin films have been inspected by scanning electron microscopy and X-ray diffraction analysis. In was concluded that precursors sols were stable in period of seven days, with insignificant change in particle size and viscosity. Phase composition of obtained films was free of secondary phases, and there was no chemical interaction with the silicon substrate. Thickness of BaTiO3 films was around 300 nm, with crack free and uniform surface, and grain size in range between 50 and 100 nm.

  104  

Investigation of mechanical and electrical properties of Cu-based composites reinforced with micro and nano ZrB2 particles

 Jovana Ružić1, Jelena Stašić1, Davor Atanasijević2, Karlo Raić3, Dušan Božić1

1Materials Department, Institute of Nuclear Sciences “Vinča”, University of Belgrade, Belgrade, Serbia

2Innovation Center of the Faculty of Technology and Metallurgy, University of Belgrade, Belgrade, Serbia

3Faculty of Technology and Metallurgy, University of Belgrade, Belgrade, Serbia

The Cu-based composites reinforced with micro and nano ZrB2 particles was consolidated via powder metallurgy processing by combining mechanical alloying and hot pressing. Powder mixture of copper (94.78 wt.%), zirconium (4.1 wt.%) and boron (1.12 wt.%) was used as a starting material. Mechanical alloying of powder mixture was carried out at various times– from 5 up to 30 hours and samples were taken on every five hours. All the specimens of mechanically alloyed powders were hot pressed up to nearly theoretical density ,in argon atmosphere, at the temperature of 950˚C,with retention time 2.5 hours and pressure of 35 MPa. Mechanically alloyed powders and hot-pressed samples of copper based composites with 7 vol.%ZrB2 were characterized using X-ray diffraction and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometry(EDS).Mechanical properties of the Cu-7vol.%ZrB2 alloy was investigated, and results showed that hardness and compressive strength of hot-pressed samples increased as the milling time increased. Distribution of micro and nano ZrB2 particles and presence of agglomerates in the Cu matrix directly depend on the milling time and show strong influence on mechanical properties and fracture of Cu-7 vol.% ZrB2 alloy. Electrical conductivity also shows the strong dependence of the time of mechanical alloying. Addition of ZrB2 particles decreases electrical conductivity of copper but despite these fact, Cu-7 vol.% ZrB2 alloy can be marked as highly conductive alloys (samples made of mechanically alloyed powders milled longer than 20h).In the present study, the mechanical properties of copper based composite prepared by hot pressing of mechanically alloyed powders were predicted using Artificial Neural Network (ANN) approach. Experimental results of specimens have shown a consistency with predicted results of ANN.                

 

 105  

Application of new synthesized ferrite nanoparticles for preparation of modified carbon paste electrode

Dalibor M. Stanković1, Sandra Škrivanj2, Aleksandar S. Nikolić2, Predrag Vulić3,

Dragan D. Manojlović2

1 Innovation Centre Faculty of Chemistry, University of Belgrade, Belgrade, Serbia 2 Faculty of Chemistry, University of Belgrade, Belgrade, Serbia

3 Faculty of Mining and Geology, Belgrade, Serbia

Ferrite nanoparticles with different amount of cobalt were synthesized and characterized using scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD). This work describes a new type of modified glassy carbon paste electrode based on different Co-ferrites. The electrode was used for the determination of nanomolar level of copper ions in natural waters using differential pulse anodic stripping voltammetry, DPASV. A significant increase in current was achieved at the modified electrode in comparison with the bare glassy carbon paste electrode. Electrochemical parameters such as percentage of modifier, accumulation time and potential, pH and the optimized amount of cobalt in the ferrites were determined. The best voltammetric response was observed for Co0.5Fe0.5Fe2O4 when percentage of modifier was 3 %, pH of supporting electrolyte acetate buffer 4.5, deposition potential -0.3 V and deposition time 4 min. Influence of possible interferences were determined. Thus prepared electrode displays selective detection toward copper ions, detection limit of 44 nM and it was successfully applied for the determination of copper ions in water samples.    

  106  

Electrochemical behavior of acid activated clays

Tihana Mudrinić1, Zorica Mojović1, Aleksandra Milutinović-Nikolić1, Davor Lončarević1, Božana Čolović2, Vukoman Jokanović2, Dušan Jovanović1

1University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Center of Catalysis and Chemical Engineering, Belgrade, Serbia

2University of Belgrade, Vinča Institute of Nuclear Sciences, Belgrade, Serbia

Smectites are phylosillicates of 2:1 type, meaning that octahedral sheet is sandwiched between two tetrahedral sheets. Due to isomorphous substitutions (Al3+ or Fe3+ for tetrahedral Si4+ and Mg2+, Fe2+ or Fe3+ for octahedral Al3+) these sheets have resulting negative charge. Hydrated cations in interlayer region neutralize negative charge. Acid activation of clays consists of mixing clay with acid solution. During acid treatment of clay interlayer cations are replaced by H+ ions what is followed by dissolution of structural cations. The extent of acid activation can be controlled by several factors: the concentration of acid, the ratio between clay and acid solution, temperature and duration of contact between acid and clay. In this paper is to investigate acid activation of smectite under very mild conditions. The purpose of this activation is exposing of present Fe2+/Fe3+ ions to the environment and subsequent investigation of obtained material as an electrode material. The obtained materials were characterized by XRD and FTIR technique.

According to X-ray diffraction patterns smectite is the main constituent of the investigated clay. The obtained basal spacing d001 =1.52 indicates that Ca2+ is the main exchangeable cation, defining raw clay as Ca-bentonite. The XRD analysis confirmed that conditions applied for acid activation were mild enough not to disturbe crystal structure of smectite. The lines corresponding to smectite (001 and 060) are present at sample treated with the highest used concentration although in lower intensity indicating that dissolution of clay mineral was partial as intended.

The three bending vibrations of hydroxyl groups associated with Al3+, Fe2+ and Mg2+ ( 915 cm−1, 875 cm−1 and 848 cm−1) were present in the FTIR spectra of starting and acid activated samples confirming that acid activation did not completely removed iron ions from smectite framework.

The acid activated clay samples were tested as electrode materials in acidic electrolyte, 0.1 M H2SO4. Aside from current rise at potential range limits due to hydrogen and oxygen evolution, presented CV’s have only one feature at potential around 0.4 V. This peak is ascribed to Fe3+/Fe2+ oxidation/reduction process. The current maxima are obtained for samples treated with 1 M and 4.5 M HCl. The observed potential for oxido-reduction for Fe3+/Fe2+ couple are lower than the standard potential for aqueous Fe3+/Fe2+ couple (+0.77 V vs SHE). The reduction potential is lower for structural Fe3+ than for solution Fe3+. The shift in reduction potential observed for different samples is driven by change of the ratio of Fe(II) to Fe(III) species. The Fe3+/Fe2+ ratio can significantly influence the application of material as catalyst. The acid activation provides an easy way to modify clay to desired effect.

 

 107  

Magnetic properties of ultrasmall iron-oxide nanoparticles

Dušan Milivojević1, Branka Babić-Stojić1, Vukoman Jokanović1, Zvonko Jagličić2, Darko Makovec3, Nataša Jović1

1Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia 2Institute of Mathematics, Physics and Mechanics, Ljubljana, Slovenia

3Department for Materials Synthesis, Jožef Stefan Institute, Ljubljana, Slovenia Structural and magnetic properties of ultrasmall magnetic nanoparticles consisting of inorganic iron oxide core and organic ester shell, dispersed in an organic fluid, synthesized via polyol route were investigated. The structure analysis shows that nanoparticles are crystalline, less then 3 nm in size, mutually clearly separated. The magnetic properties are in accordance with the size of the nanoparticles and do not indicate interparticle interactions. The particles show pure superparamagnetic behavior with very low blocking temperature. ZFCFC bifurcation and ac susceptibility peaks are at temperatures TB < 12 K. The properties of fluid were compared with dried powder sample. Drying of fluid brings about interactions between the magnetic nanoparticles that considerably affect spin dynamics of the particles. The surface of nanoparticles has a significant influence on their behavior. The Mössbauer parameters indicate existence of γ-Fe2O3 core and non-stoichiometric surface layer. Magnetic field dependent magnetization analysis suggests smaller apparent size of the particles d0= 0.56 nm. High magnetic anisotropy due to surface layer anisotropy was measured to be of the order 106 erg/cm3 that is two orders of magnitude higher than that in bulk material.

  108  

List  of  authors  and  coauthors:  

 

1.  Aleksić  I.    .....................................83                    2.  Aleksić  M.    ...................................81  3. Aleksić  V.    .....................................65  4. Andrić  Lj.    .....................................23,  44,  56  5. Anđić  Z.    .......................................28  6. Antonijević  Đ.    ..............................73  7. Atanasijević  D.    ............................104  8. Babić  B.    ........................................89,  95  9. Babić  Stojić  B.    ..............................107  10. Babić-­‐Ivančić  V.    ...........................15,  85,  86  11. Bajac  B.    ........................................103  12. Bajat  J.    ..........................................29  13. Bajić  N.    ..........................................32  14. Bajkin  B.    .........................................71  15. Barac  R.    .........................................79,  80  16. Baraković  A.    ..................................24,  54  17. Baraković  D.    ..................................53,  54  18. Bartulović  Z.    ..................................56  19. Bibić  N.    ..........................................97,  98  20. Blagojević  D.    ..................................71  21. Bobkov  A.    .......................................55  22. Borka  D.    .........................................35  23. Bošković  I.    ......................................19  24. Božić  D.    ..........................................104  25. Branković  G.    ...................................94  26. Cvejić  Ž.    ..........................................103  27. Čebela  M.    .......................................87,  88,  89,  91,  93  28. Čolović  B.    .......................................34,  60,  73,  106  29. Ćetenović  B.    ...................................69,  70  30. Ćirić  Marjanović  G.    .........................102  31. Devčerski  A.    ....................................90  32. Dojčinović  B.    ...................................61  33. Došen  A.    .........................................89  34. Ducman  V.    ......................................57  35. Dugić  P.    ..........................................65  36. Dutour  Sikirić  M.    ............................33,  101  37. Đeri  A.    ............................................74,  75,  76,  77,  78  38. Đorđević  Lj.    ....................................81  39. Đurđić  E.    .........................................103  40. Gašić  J.    ............................................79,  80  41. Gojić  M.    ..........................................18  42. Grbić  B.    ...........................................64  43. Hercigonja  R.    ..................................87,  102  44. Hinić  B.    ...........................................48  45. Husagić  R.    .......................................52  46. Ilić  S.    ...............................................87,  88,  91,  93  

 

 109  

47. Isaković  H.    .......................................54  48. Jagličić  Z.    .........................................107  49. Jakimovska  A.    ..................................67  50. Janković  O.    .......................................77  51. Jenko  M.    ..........................................60,  82  52. Jokanovic  V.    .....................................14,  34,  37,  59,  60,  66,  69,  70,  71,  72,  81,  106  53. Jokanović  B.    .....................................59  54. Jokić  B.    .............................................99  55. Jokić  M.    ............................................29  56. Jordanov  D.    ......................................84,  92  57. Josipović  R.    .......................................74,  75,  76,  77,  78  58. Jotanović  M.    .....................................63  59. Jovanović  D.    .....................................106  60. Jović  M.    ............................................61  61. Jović  N.    .............................................107  62. Jurašin  D.    ..........................................100,  101  63. Kamberović  Ž.    ...................................28  64. Karađžić  I.    .........................................37  65. Kisić  D.    ..............................................96  66. Kljajević  Lj.    ........................................92  67. Knežević  N.    .......................................74,  75,  76,  77,  78  68. Kojić  Ž.    ..............................................74,  75  69. Kontrec  J.    .........................................86  70. Korać  M.    ..........................................28  71. Kosec  B..............................................18  72. Kožuh  S.    ...........................................18  73. Krgović  M.    ........................................19  74. Krstić  J.    .............................................61  75. Kusigerski  V.    ....................................92  76. Kuveždić  H.  .......................................86  77. Lazić  G.    ............................................25,  42,  43  78. Lončarević  D.    ..................................106  79. Lopičić  S.    .........................................83  80. Luković  J.    .........................................93,  94,  95  81. Ljubić  O.    ..........................................50  82. Magić  M.    .........................................72  83. Majstorović  J.    ..................................90  84. Makarić  S.    .......................................100  85. Makovec  D.    .....................................107  86. Maksimović  V.    .................................91  87. Malešević  J.    .....................................47  88. Manojlović  D.    ..................................61,  105  89. Morasi  Piperčić  S.    ...........................100  90. Martinović  S.    ...................................26      91.  Markićević  N.    .................................102  92. Marković  D.    ....................................37,  69,  70,  71,  72  93. Matović  B.    ......................................84,  87,  88,  89,  90,  91,  92,  94,  95  94. Mićić  V.    ...........................................62,  63,  65  95. Milenković  N.    .................................57  96. Milivojević  D.    .................................36,  107  

  110  

97. Milovanović  B.    ...............................84  98. Milutinović  Nikolić  A.    ....................106  99. Minović  T.    ......................................93  100. Mirković  M.    .................................87,  88,  89,  93  101. Mitić  A.    ........................................79,  80  102.  Mojović  Z.    ...................................106  103. Mudrinić  T.    ..................................106  104. Najman  S.    .....................................81  105. Nakić  N.    .......................................101  106. Nasov  I.    ........................................16,  67  107. Nedeljkov  V.    .................................83  108. Nedić  Vasiljević  B.    ........................88  109. Nenadović  M.    ...............................96,  99  110. Nešić  J.    ..........................................61  111. Nikolić  A.    ......................................105  112. Nikolić  B.    ......................................22  113. Nikolić  M.    .....................................79,  80  114. Novak  S.    .......................................100  115. Novaković  M.    ...............................97,  98  116. Omerašević  M.    .............................87,  88,  89,  91  117. Pantić  J.    ........................................93,  94,  95  118. Pašti  I.    ..........................................95  119. Pavlović  M.    ..................................29,  44  120. Pejović  B.    .....................................62,  63  121. Perić  T.    ........................................71  122. Petković  M.    .................................65  123. Petrov  M.    ....................................56  124. Petrović  B.    ...................................71  125. Petrović  Đ.    ...................................71  126. Petrović  M.    ..................................38  127. Petrović  V.    ...................................40,  58  128. Petrović  Z.    ...................................63,  65  129. Popović  J.    ....................................79,  80  130. Popović  M.    ..................................97,  98  131. Pošarac  Marković  M.    ..................90  132. Potočnik  J.    ...................................99  133. Prekajski  M.    .................................73,  94,  95  134. Primožić  I.    ...................................100  135. Prostran  M.    ..................................83  136. Radenković  G.    ..............................79,  80  137. Radić  N.    .......................................31,  64  138. Radman  Kuzmanović  I.    ................74,  75,  76,  77,  78  139. Radoičić  M.    ..................................73  140. Radosavljević  Mihajlović  A.  ..........88  141. Raić  K.    ..........................................104  142. Rakić  S.    ........................................103  143. Rakočević  Z.    .................................96,  99  144. Ranogajec  J.    .................................57  145. Riđošić  M.    ....................................29  146. Roglić  G.    .......................................61  

 

 111  

147. Rosić  M.    .......................................84,  89,  92,  93  148. Rudić  O.    .......................................57  149. Rudolf  R.    .....................................17,  59  150. Ružić  J.    ........................................104  151. Selmani  A.    ...................................101  152. Simendić  B.    ..................................58  153. Simić  S.    ........................................65  154. Spasić  S.    .......................................83  155. Spasojević  V.    ................................92  156. Srdić  V.    ........................................103  157. Stambolić  A.    .................................82  158. Stanković  D.    .................................105  159. Stanojević  M.    ................................83  160. Stašić  J.    ........................................104  161. Stević  D.    .......................................46,  47  162. Stojadinović  S.    ..............................64  163. Stojanović  D.    ................................96  164. Stojiljković  M.    ...............................92  165. Stojmenović  M.    .............................94,  95  166. Šaponjić  A.    ....................................91  167. Šehić  Dž.    .......................................68  168. Šerić  B    ...........................................85  169. Šimunović  D.    .................................86  170. Škrivanj  S.    .....................................105  171. Šljukić  B.    .......................................102  172. Špiljak  B.    .......................................51  173. Tadić  N.    .........................................64  174. Tomić  M.    .......................................29,  62,  63  175. Trajkovska  Petkovska  A.    ...............16,  30,  67  176. Tripković  Đ.    ...................................103  177. Vasilić  R.    ........................................64  178. Vasiljević  P.    ...................................81  179. Veselinović  V.    ...............................74,  75  180. Videnović  N.    .................................49  181. Vilotijević  M.    ................................59,  60  182. Vlahović  M.    ..................................27  183. Volkov  Husović  T.    .........................21,  44,  90  184. Vučetić  M.    ....................................45  185. Vučetić  N.    .....................................45  186. Vučetić  S.    ......................................57  187. Vučetić  V.    ......................................45,  47  188. Vučić  V.    .........................................37  189. Vujačić  V.    ......................................22  190. Vukčević  M.    ..................................19  191. Vukmirović  J.    .................................103  192. Vuković  A.    .....................................69,  70  193. Vulić  P.    ..........................................61,  105  194. Xiong  X-­‐Y.    ......................................55  195. Zec  S.    .............................................91  196. Zhang  K.    ........................................98  

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197. Žabar  Popović  A.    ...........................81  198. Živković  S.    .....................................39,  79,  80  

 

 

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2014Rosov pinSECOND REGIONAL ROUNDTABLE: REFRACTORY, PROCESS INDUSTRY AND NANOTECHNOLOGY

Programme andThe Book of Abstracts

Rosov pin 2014

SECOND REGIONALROUND TABLE:

CENTER FOR INDUSTRIAL AND TECHNOLOGICAL DEVELOPMENT ”ANDREVLJE”, FRUŠKA GORA, SERBIA, OCTOBER 23-24, 2014

Organised by:> Vinča Institute of Nuclear Sciences, Belgrade> Engineering Academy of Serbia, Belgrade> Lafarge BFC d.o.o. Beočin > REAL S d.o.o. Beograd

“ROSOV PIN 2014 focuses on connecting different types of nanotechnology with conventional technologies in refractory and process industry. Nanotechnologies are not only present in modern high tech technology, but also in conventional technology applied in the process industry and refractory, giving the materials a completely new mechanical and corrosion properties.”

CENTER FOR INDUSTRIAL AND TECHNOLOGICAL DEVELOPMENT ”ANDREVLJE”, FRUŠKA GORA, SERBIA, OCTOBER 23-24, 2014

REFRACTORY, PROCESS INDUSTRY AND NANOTECHNOLOGY

ENGENEERING ACADEMYOF SERBIA VINČA INSTITUTE

OF NUCLEAR SCIENCES