1422 17 JUNE 2016 • VOL 352 ISSUE 6292 sciencemag.org SCIENCE

Edited by Sacha Vignieri

and Jesse SmithIN OTHER JOURNALS

APPLIED PHYSICS

Organic solar cells tuned by blending Electrical engineers can fine-

tune the energetics of rigid

photovoltaics and transistors

by blending different semicon-

ducting materials. However,

it’s hard to apply this tuning

protocol to the flexible class of

carbon-based semiconductors.

Schwarze et al. now show that

continuous band energy tuning

is indeed possible by varying the

blend ratios of certain organic

phthalocyanines and their fluori-

nated or chlorinated derivatives

(see the Perspective by Ueno).

They demonstrated the effect,

which they attribute to quadru-

polar interactions, in model solar

cells. — JSY

Science, this issue p. 1446;

see also p. 1395

bone was shaped to a defect in

miniature pigs, and then stem

cells were cultured on the bone.

To mimic the manufacturing

and transport chain for human

facial bone reconstruction, the

bioreactor containing living

bone was shipped to the site of

surgery. The implanted scaffold

material integrated successfully

with host tissue, formed new

bone, and was vascularized.

— MLF

Sci. Transl. Med. 8, 343ra83 (2016).

MOLECULAR JUNCTIONS

Stable molecular switches Many single-molecule current

switches have been reported,

but most show poor stabil-

ity because of weak contacts

to metal electrodes. Jia et al.

covalently bonded a diaryle-

thene molecule to graphene

electrodes and achieved stable

photoswitching at room tem-

perature (see the Perspective

by Frisbie). The incorporation

of short bridging alkyl chains

between the molecule and

graphene decoupled their pi-

electron systems and allowed

fast conversion of the open and

closed ring states. — PDS

Science, this issue p. 1443;

see also p. 1394

STEM CELLS

Tracking stem cell fate in time and space After injury and during homeo-

stasis, tissues rely on the

balance of cell loss and renewal.

Rompolas et al. visualized

individual stem cells over their

lifetime in the epidermis of live

mice. Tracking stem cells over

multiple generations revealed

that tissue homeostasis in

the mouse epidermis is not

maintained by asymmetric cell

division as previously thought,

but through the coordination

of sibling cell fate and lifetimes.

Furthermore, differentiating

stem cells reused the exist-

ing spatial organization of the

epidermis. — BAP

Science, this issue p. 1471

MEDICINE

Replacing factor VIII replacement?Hemophilia A is a bleeding

disorder caused by a deficiency

of factor VIII, a protein essential

for blood clotting. Injection of

recombinant or plasma-derived

factor VIII is an effective

prophylactic treatment. Factor

replacement therapy has draw-

backs, however, as it requires

multiple injections each week

and can induce antibodies that

inhibit factor VIII. Shima et al.

clinically tested an alternative

therapy: an engineered bispecific

Molecular structural properties

of organic semiconductors.

ATMOSPHERIC AEROSOLS

Nanoparticle growth in

the CLOUD chamber

Atmospheric ions and small acid-base clusters can

participate in the growth of atmospheric nanoparticles.

These species generally are not considered in models of

aerosol formation from sulfuric acid vapor and so have

not been included in estimates of new particle growth

rates. Lehtipalo et al. measured growth rates of particles

smaller than 3 nm in the CLOUD chamber at CERN and found

that compounds that stabilize sulfuric acid clusters can con-

trol the magnitude of these effects, leading to higher growth

rates and affecting the growth mechanism. — HJS

Nat. Comm. 10.1038/ncomms11594 (2016).

A view of the interior of the CERN CLOUD chamber

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TISSUE ENGINEERING

Saving faceBone grafts from the patient

are currently used to cor-

rect facial deformities, but a

biomaterials-based approach

would be useful. Bhumiratana

et al. designed a facial recon-

structive strategy based on

stem cells, decellularized bone,

and a custom-designed perfu-

sion bioreactor. First,

RESEARCH | IN SCIENCE JOURNALS

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antibody called emicizumab

that mimics the critical function

of factor VIII, which is to bridge

together clotting factors IXa and

X. Nineteen patients with severe

hemophilia A were injected with

emicizumab once a week for 12

weeks. Most patients showed

reduced bleeding rates without

adverse effects. — PAK

N. Engl. J. Med. 374, 21 (2016).

CLIMATE CHANGE ECOLOGY

Mountain forests in a warming worldPaleoecological records of

past distributions of plants and

animals can be useful guides to

their potential responses to cur-

rent changing climate. Ivory et al.

compared the present distribu-

tions of several common species

of African mountain forests with

their distributions (inferred from

pollen records) in the mid-Holo-

cene and Last Glacial Maximum

(6000 and 21,000 years ago,

respectively). Paleoclimate data

indicate that these species occu-

pied warmer habitats than those

in which they currently occur,

in some cases expanding their

ranges into the lowlands. Hence,

Even monomers such as isobu-

tylene yielded highly branched

polymers when the highly

electron-withdrawing fluorinated

initiator was used. — PDS

J. Am. Chem. Soc. 10.1021/

jacs.6b03568 (2016).

PSYCHOLOGY

How to advertise eco-friendly productsHave you ever found yourself

trying to decide whether to buy

an eco-friendly washing powder

or one of the regular alterna-

tives? Goldsmith et al. show that

such decisions depend on the

mental state of the consumer.

The authors induced an abstract

mindset by asking participants

to write about their life one year

from tomorrow. In this mindset,

the participants were less likely to

choose an eco-friendly prod-

uct promoted for its economic

benefits. In contrast, they tended

to act based on economic

self-interest when in a concrete

mindset induced by writing about

their life tomorrow. So a television

advertisement aiming to influ-

ence future purchases may be

more successful if it emphasizes

environmental benefits; for in-

store decisions, self-interest is

the rule of the day. — JFU

Nat. Clim. Change 10.1038/

nclimate3019 (2016).

AGING

Longer life? It’s all in the headCaloric restriction extends life

span and helps ward off diseases

of aging in model organisms

and may do so in primates as

well. It’s not pleasant, though,

so a way to mimic its effect with

a drug would be more appeal-

ing. Lucanic et al. screened for

such a compound in the worm

Caenorhabditis elegans and

found one that extended life

span in a manner similar to

dietary restriction. Experiments

to trace the point of action of

the compound indicated that it

may act by limiting activity in a

neuronal pathway that senses

the presence of food. Thus,

sensory signaling pathways

might be targets for agents that

could mimic beneficial effects of

dietary restriction on aging and

health span. — LBR

Aging Cell. 10.1111/acel.12492 (2016).

present-day distributions of

these species are not necessar-

ily representative of their entire

climatic niche space. Their future

response to a warming climate

may thus be more constrained by

human land use than by increas-

ing temperature. — AMS

Global Ecol. Biogeogr.

10.1111/geb.12446 (2016).

POLYMER CHEMISTRY

Photoinitiation with boron clustersNonmetallic photoinitiators of

polymerization are gaining inter-

est for biomedical and electronics

applications in which metal

compounds are toxic or their

presence reduces performance.

Messina et al. report on boron

clusters [B12

(OR)12

, where R is

a phenyl or pentafluorophenyl

group] that act as photoinitiators

with blue light for the polymeriza-

tion of olefins. These compounds

photoionize and can initiate the

reaction via one-electron transfer

(creating a cluster radical anion

and a monomer radical cation) to

both electron-rich and electron-

deficient styrene monomers at

very low loadings (0.005 mol %).

PALEONTOLOGY

Dino dung beetles

Insects are one of the most spe-

ciose groups, and the rise in their

diversity has often been attrib-

uted to the rise of angiosperms.

However, not all insects are herbi-

vores, and the scarab family of beetles

is a notably diverse example. Gunter et

al. asked what drove this family’s high

levels of speciation and found that the

monophyletic group’s diversification

also appears to be indirectly connected

to the emergence of angiosperms. In

particular, they found that dung beetles

experienced a rapid radiation at about

the time that angiosperms became a

part of dinosaur diets. Thus, the rise

of more easily digestible angiosperms

allowed beetles to process dung long

before the rise of mammals. — SNV

PLOS ONE 10.1371/journal.pone.0153570

(2016). Dinosaur dung led

to dung beetle diversity.

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Replacing factor VIII replacement?Paula A. Kiberstis

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