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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
PH
OT
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T)
SC
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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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17 JUNE 2016 • VOL 352 ISSUE 6292 1423SCIENCE sciencemag.org
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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
DOI: 10.1126/science.352.6292.1422-b (6292), 1422-1423.352Science
ARTICLE TOOLS http://science.sciencemag.org/content/352/6292/1422.2
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