November 5, 2013
In This Issue
Tunable p-n heterojunction diodes
orphanages. To account for the genetic and environmental factors
that influence human studies, the authors mimicked the impoverished caregiving provided by the children’s orphanages in preweaned mice by decreasing nesting material available to the dams
for a limited time. The findings uncover lasting effects of early life
experiences on human behavior and development, the authors report. Early-onset and long lasting changes in anxious behavior and
amygdala function were observed in mice exposed to disorganized
parental care early in life, mirroring the heightened emotional reactivity and amygdala changes in orphanage-reared children. The
changes persisted long after the children were removed from the
stressor, and did not diminish with the development of prefrontal
regulatory regions in the brain. According to the authors, the findings highlight how early-life stress can lead to altered brain circuitry and emotional dysregulation, and suggest that such children
may benefit from early intervention. — A.G.
The p-n junction diode, a ubiquitous building block of modern
electronics, has numerous applications ranging from integrated circuits to photovoltaics and lasers. However, the recent emergence of
extremely thin materials suggests that this integral electronic component can be scaled down to thicknesses of a few atoms, potentially enhancing its functionality even further. Deep Jariwala et al.
(pp. 18076–18080) demonstrate the fabrication and operation of a
p-n heterojunction diode—an interface that passes current between
dissimilar semiconductor types—based on atomically thin molybdenum disulfide (MoS2) and sorted semiconducting single-walled
carbon nanotubes (SWCNTs). The electrical characteristics of these
heterojunction diodes can be precisely tuned to achieve behavior
ranging from insulating to rectifying. Furthermore, the diodes respond strongly to optical irradiation with a fast photoresponse and
quantum efficiency that compares favorably with other recently
reported atomically thin nanomaterials. By combining the highly
desirable electrical properties of SWCNTs with the rapidly expand- Maternal bond might influence bonobo
ing field of atomically thin materials, the authors report, the p-n social competence
heterojunction concept might lead to a new generation of ultrathin,
Previous studies have suggested that social skills, such as expresshigh-performance electronics and optoelectronics. — T. J.
ing sympathy and responding to others’ distress, are positively tied
to emotion control in humans. Zanna Clay and Frans de Waal (pp.
18121–18126) examined the development of social and emotional
competence in our close primate relatives: bonobos (Pan paniscus).
The authors studied a range of social skills, including the apes’ abilities to sustain social interaction through play bouts, overcome selfdistress, and console distressed peers through comforting acts
such as touching, stroking, kissing, and embracing, among a group
of juvenile bonobos in a forested sanctuary in the Democratic
False-colored scanning electron micrograph of a carbon nanotube/
MoS2 heterojunction diode.
Effects of early-childhood stress on
behavior and brain development
Early-childhood stress, such as the disorganized care received by
children reared in some orphanages, has been linked to psychopathology later in life but the neurobiological underpinnings
of these outcomes remain unclear. Matthew Malter Cohen et al.
(pp. 18274–18278) studied 16 orphanage-reared children, ages
11 and younger, and a group of 10 children who had not lived in One juvenile embraces another after the other loses a fight.
November 5, 2013 | vol. 110 | no. 45 | 18025–18026
Republic of Congo. Whereas some bonobos were born and
mother-reared at the sanctuary, most arrived as orphans rescued
in the wild from illegal