biofisika membran-11-2009 eng.ppt

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REVIEW AND Theoretical

Modeling membrane

Basically, to explain the transportphenomena in the membrane. then

conducted a review of theoretical

and modeling.



Electrochemical Reviews

• Based on the membraneelectrochemical potential canbe formulated as follows:

• i

=

i

o

kT ln C

i

Z

i

q

Reviews electric force and

electric field:

•Ei = -

•Fi = qi Ei



Current of ionic

• J i = q Di ZiCiEi/(kT)

• With substituted Ei,

• Get Nerns – planck equation

dx

d

kT

CDqZ

x

CqDZJ ii

22

iiiii



IMPEDANCE

The conductance value can be obtained Norcapacitance :

m

~

m

~

CIG

1Z

LICDZ

kTL

q

1Z

0~

ii

2

i

2

~



conduktance

Capacitance

ii

2

i

2

CDZkTL

q

L

0

• This is to explain the theoretical

formulation of the impedance,

capacitance and inductance of themembrane that interact with the

solution ionic or ion



Membrane modelling• Tues membrane can be modeled by

electric circuits consisting of a

combination of capacitors and

inductors (coster)

C C

G G G



Analisis impedansi

•

Combined series between Z1 and Z2and see ZM formulation, it willgenerate value membraneconductance and capacitance.

1

~

1

~

CIG

11Z

2

~

2

2

~

CIG

1Z

m

~

m

m

~

CIG

1Z



222

222

)2C1C()2G1G(

)1G2C2G1C()2G1G(2G1GGm

222

222

)2C1C()2G1G(

)2C1C(2C1C2C1G1C2GCm

Cm Gm

f



TRANSPORT OF ION

• If we consider a charged ion, and hehas the energy itself.

• Overall ions basically do not want to

be in the area of energy exceeds theenergy itself.

• Energy self-ions are formed due tothe electrostatic energy has to do

with the dielectric constant



• In view of the basic electrical

theory of self-electrostatic

energy is the integral of theelectric field

~

0r

r 4

2

0

2

0

dr )4(

)zq(5.0

u 4

2

)d8(

)zq(u

0

2

• Z ion valency

• d pore size



Membran

• u

• u

The membrane has a dielectric constant

lower than the water, then the energy itself

is higher than in water.Ions in the membrane transport of energy is

needed or something that makes the energy

ions increases. Or lower energy membranes



This is lower energy self-ions

when passing through the

membrane• A. thickness Factor

• L = thickness

• The contribution of the membrane

thickness is very small

)2

ln()l4(

)zq(u

mw

w

0m

2



• B. Ion kristal

• Ions across the membrane is considered

an ionic crystal (crystal form), notcovered in water ions

Ketoka ion energy Pebedaan are the

inner and outer membrane is:

Slightly larger than the thickness factor

)11

()d8(

)zq(u

wm0

2



C. hydrated ions

•

with the ions of water covered the ionradius will tend to dilate which causesa small ion energy.

• With the arising water interfacetension between water and membrane

(I). Thus the addition of energy (u2)due to these interface

• U2=4Ib2,

• b is hydrated ion radius

• Thus the total energy differencebecomes



D. Ion pairs

• Ions in the opposite sign to form a pair

and then move together through themembrane

If d + and d-represents the radius of the

positive and negative ions, and j the

distance between them, then the

electrostatic energy of this ion pair is

) j4(

)zq(

)d8(

)zq(

)d8(

)zq(u

m0

2

m0

2

m0

2



• J d+ + d _

•If considered these ionstogether then

• J = d+ + d _ ,

• For d+ = d _

• it is the same as

• before

)dd(4()zq(

)d8()zq(

)d8()zq(u

m0

2

m0

2

m0

2

)d8(

)zq(u

m0

2



E. Ion Transport through pore

• if there are pores in the membrane

is the membrane area which there

is a high dielectric constant, so

that the ions would prefer to gothrough the area

)r 4(K )zq(dum0

2



Conductace of

membrane• In general, the membrane

conductance is a function of time,

which is exponential function andrelated to changes in self energy of

ion

)kT/duexp(GG 0

biofisika membran-11-2009 eng.ppt

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