1 Liquefied gas electrolytes for electrochemical energy storage devices
Cyrus S. Rustomji, Yangyuchen Yang, Tae Kyoung Kim…Hyeseung Chung, Y. Shirley Meng
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Electrochemical capacitors and lithium-ion batteries have seen little change in their electrolyte chemistry since their commercialization, which has limited improvements in device performance. Combining superior physical and chemical properties and a high dielectric-fluidity factor, the use of electrolytes based on solvent systems that exclusively use components that are typically gaseous under standard conditions show a wide potential window of stability and excellent performance over an extended temperature range. Electrochemical capacitors using difluoromethane show outstanding performance from –78° to +65°C, with an increased operation voltage. The use of fluoromethane shows a high coulombic efficiency of ~97% for cycling lithium metal anodes, together with good cyclability of a 4-volt lithium cobalt oxide cathode and operation as low as –60°C, with excellent capacity retention.
2 Atomic structure of the human cytomegalovirus capsid with its securing tegument layer of pp150
Xuekui Yu, Jonathan Jih, Jiansen Jiang, Z. Hong Zhou（周宏，加州大学洛杉矶分校）
Herpesviruses possess a genome-pressurized capsid. The 235-kilobase genome of human cytomegalovirus (HCMV) is by far the largest of any herpesvirus, yet it has been unclear how its capsid, which is similar in size to those of other herpesviruses, is stabilized. Here we report a HCMV atomic structure consisting of the herpesvirus-conserved capsid proteins MCP, Tri1, Tri2, and SCP and the HCMV-specific tegument protein pp150—totaling ~4000 molecules and 62 different conformers. MCPs manifest as a complex of insertions around a bacteriophage HK97 gp5–like domain, which gives rise to three classes of capsid floor–defining interactions; triplexes, composed of two “embracing” Tri2 conformers and a “third-wheeling” Tri1, fasten the capsid floor. HCMV-specific strategies include using hexon channels to accommodate the genome and pp150 helix bundles to secure the capsid via cysteine tetrad–to-SCP interactions. Our structure should inform rational design of countermeasures against HCMV, other herpesviruses, and even HIV/AIDS.
(导读 郭怿暄)人类巨细胞病毒（HCMV）是已知基因组最大的疱疹病毒，但其衣壳尺寸仅与同类其他病毒相近。本研究通过冷冻电镜技术解析了HCMV衣壳结构，其中包含疱疹病毒保守衣壳蛋白MCP, Tri1, Tri2和SCP，以及HCMV特异的外被蛋白pp150等共约4000个分子以及62种不同变构体，此结构为疱疹状病毒甚至HIV/AIDS的治疗提供基础。
3 Restoring auditory cortex plasticity in adult mice by restricting thalamic adenosine signaling
Jay A. Blundon, Noah C. Roy, Brett J. W. Teubner…Burgess B. Freeman III, Stanislav S. Zakharenko
Circuits in the auditory cortex are highly susceptible to acoustic influences during an early postnatal critical period. The auditory cortex selectively expands neural representations of enriched acoustic stimuli, a process important for human language acquisition. Adults lack this plasticity. Here we show in the murine auditory cortex that juvenile plasticity can be reestablished in adulthood if acoustic stimuli are paired with disruption of ecto-5′-nucleotidase–dependent adenosine production or A1–adenosine receptor signaling in the auditory thalamus. This plasticity occurs at the level of cortical maps and individual neurons in the auditory cortex of awake adult mice and is associated with long-term improvement of tone-discrimination abilities. We conclude that, in adult mice, disrupting adenosine signaling in the thalamus rejuvenates plasticity in the auditory cortex and improves auditory perception.
4. A human-driven decline in global burned area
N. Andela, D. C. Morton, L. Giglio, Y. Chen, G. R. van der Werf, P. S. Kasibhatla, R. S. DeFries, G. J. Collatz, S. Hantson, S. Kloster, D. Bachelet, M. Forrest, G. Lasslop, F. Li, S. Mangeon, J. R. Melton, C. Yue, J. T. Randerson.
Fire is an essential Earth system process that alters ecosystem and atmospheric composition. Here we assessed long-term fire trends using multiple satellite data sets. We found that global burned area declined by 24.3 ± 8.8% over the past 18 years. The estimated decrease in burned area remained robust after adjusting for precipitation variability and was largest in savannas. Agricultural expansion and intensification were primary drivers of declining fire activity. Fewer and smaller fires reduced aerosol concentrations, modified vegetation structure, and increased the magnitude of the terrestrial carbon sink. Fire models were unable to reproduce the pattern and magnitude of observed declines, suggesting that they may overestimate fire emissions in future projections. Using economic and demographic variables, we developed a conceptual model for predicting fire in human-dominated landscapes.
5 Estimating economic damage from climate change in the United States
Solomon Hsiang, Robert Kopp, Amir Jina…Kate Larsen, Trevor Houser
Estimates of climate change damage are central to the design of climate policies. Here, we develop a flexible architecture for computing damages that integrates climate science, econometric analyses, and process models. We use this approach to construct spatially explicit, probabilistic, and empirically derived estimates of economic damage in the United States from climate change. The combined value of market and nonmarket damage across analyzed sectors—agriculture, crime, coastal storms, energy, human mortality, and labor—increases quadratically in global mean temperature, costing roughly 1.2% of gross domestic product per +1°C on average. Importantly, risk is distributed unequally across locations, generating a large transfer of value northward and westward that increases economic inequality. By the late 21st century, the poorest third of counties are projected to experience damages between 2 and 20% of county income (90% chance) under business-as-usual emissions (Representative Concentration Pathway 8.5).
6 Carbon nanotube transistors scaled to a 40-nanometer footprint
Qing Cao, Jerry Tersoff, Damon B. Farmer, Yu Zhu, Shu-Jen Han
The International Technology Roadmap for Semiconductors challenges the device research community to reduce the transistor footprint containing all components to 40 nanometers within the next decade. We report on a p-channel transistor scaled to such an extremely small dimension. Built on one semiconducting carbon nanotube, it occupies less than half the space of leading silicon technologies, while delivering a significantly higher pitch-normalized current density—above 0.9 milliampere per micrometer at a low supply voltage of 0.5 volts with a subthreshold swing of 85 millivolts per decade. Furthermore, we show transistors with the same small footprint built on actual high-density arrays of such nanotubes that deliver higher current than that of the best-competing silicon devices under the same overdrive, without any normalization. We achieve this using low-resistance end-bonded contacts, a high-purity semiconducting carbon nanotube source, and self-assembly to pack nanotubes into full surface-coverage aligned arrays.
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7 Anti-coalescence of bosons on a lossy beam splitter
Benjamin Vest, Marie-Christine Dheur, Éloïse Devaux…Gaétan Messin, François Marquier
Two-boson interference, a fundamentally quantum effect, has been extensively studied with photons through the Hong-Ou-Mandel effect and observed with guided plasmons. Using two freely propagating surface plasmon polaritons (SPPs) interfering on a lossy beam splitter, we show that the presence of loss enables us to modify the reflection and transmission factors of the beam splitter, thus revealing quantum interference paths that do not exist in a lossless configuration. We investigate the two-plasmon interference on beam splitters with different sets of reflection and transmission factors. Through coincidence-detection measurements, we observe either coalescence or anti-coalescence of SPPs. The results show that losses can be viewed as a degree of freedom to control quantum processes.
8 Iodide management in formamidinium-lead-halide–based perovskite layers for efficient solar cells
Woon Seok Yang, Byung-Wook Park, Eui Hyuk Jung…Jun Hong Noh, Sang Il Seok
（导读 韩宇）提高钙钛矿太阳能电池（PSCs）转换效率的关键在于对缺陷能级浓度的控制。本研究表明，在甲脒铅卤化物基钙钛矿层的形成过程中引入额外的三碘阴离子可抑制深能级缺陷的形成。该缺陷控制过程将1cm2大小PSCs 的认证转换效率提高到近20％。
The formation of a dense and uniform thin layer on the substrates is crucial for the fabrication of high-performance perovskite solar cells (PSCs) containing formamidinium with multiple cations and mixed halide anions. The concentration of defect states, which reduce a cell’s performance by decreasing the open-circuit voltage and short-circuit current density, needs to be as low as possible. We show that the introduction of additional iodide ions into the organic cation solution, which are used to form the perovskite layers through an intramolecular exchanging process, decreases the concentration of deep-level defects. The defect-engineered thin perovskite layers enable the fabrication of PSCs with a certified power conversion efficiency of 22.1% in small cells and 19.7% in 1-square-centimeter cells.
9 Decoding of position in the developing neural tube from antiparallel morphogen gradients
Marcin Zagorski, Yoji Tabata, Nathalie Brandenberg…James Briscoe, Anna Kicheva
Like many developing tissues, the vertebrate neural tube is patterned by antiparallel morphogen gradients. To understand how these inputs are interpreted, we measured morphogen signaling and target gene expression in mouse embryos and chick ex vivo assays. From these data, we derived and validated a characteristic decoding map that relates morphogen input to the positional identity of neural progenitors. Analysis of the observed responses indicates that the underlying interpretation strategy minimizes patterning errors in response to the joint input of noisy opposing gradients. We reverse-engineered a transcriptional network that provides a mechanistic basis for the observed cell fate decisions and accounts for the precision and dynamics of pattern formation. Together, our data link opposing gradient dynamics in a growing tissue to precise pattern formation.
10 Hypothalamic regulation of regionally distinct adult neural stem cells and neurogenesis
Alex Paul, Zayna Chaker, Fiona Doetsch
Neural stem cells (NSCs) in specialized niches in the adult mammalian brain generate neurons throughout life. NSCs in the adult mouse ventricular-subventricular zone (V-SVZ) exhibit a regional identity and, depending on their location, generate distinct olfactory bulb interneuron subtypes. Here, we show that the hypothalamus, a brain area regulating physiological states, provides long-range regionalized input to the V-SVZ niche and can regulate specific NSC subpopulations. Hypothalamic proopiomelanocortin neurons selectively innervate the anterior ventral V-SVZ and promote the proliferation of Nkx2.1+ NSCs and the generation of deep granule neurons. Accordingly, hunger and satiety regulate adult neurogenesis by modulating the activity of this hypothalamic–V-SVZ connection. Our findings reveal that neural circuitry, via mosaic innervation of the V-SVZ, can recruit distinct NSC pools, allowing on-demand neurogenesis in response to physiology and environmental signals.
11 Emission of volatile organic compounds from petunia flowers is facilitated by an ABC transporter
Funmilayo Adebesin, Joshua R. Widhalm, Benoît Boachon…Robert C. Schuurink, Natalia Dudareva
Plants synthesize a diversity of volatile molecules that are important for reproduction and defense, serve as practical products for humans, and influence atmospheric chemistry and climate. Despite progress in deciphering plant volatile biosynthesis, their release from the cell has been poorly understood. The default assumption has been that volatiles passively diffuse out of cells. By characterization of a Petunia hybrida adenosine triphosphate–binding cassette (ABC) transporter, PhABCG1, we demonstrate that passage of volatiles across the plasma membrane relies on active transport. PhABCG1 down-regulation by RNA interference results in decreased emission of volatiles, which accumulate to toxic levels in the plasma membrane. This study provides direct proof of a biologically mediated mechanism of volatile emission.
（导读 郭怿暄）植物合成多种挥发性分子来帮助自身繁殖和防卫，同时还可服务于人类， 影响大气化学和气候，但这些分子如何从细胞中释放仍不清楚。本研究通过研究矮牵牛花的ABC转运蛋白（PhABCG1）发现挥发性物质通过主动运输跨越细胞膜。这一发现为生物体内挥发性物质的释放机制提供了直接证据。
12 Plant diversity increases with the strength of negative density dependence at the global scale
Joseph A. LaManna, Scott A. Mangan, Alfonso Alonso…Sandra Yap, Jonathan A. Myers
（导读 刘威尔）热带地区较高的生物多样性可能是由植物及其天敌间专一性相互作用引发的种内负密度效应（conspecific negative density dependence, CNDD）维持的。本文通过分析世界范围内24个森林样地中3000多个物种近240万株树木，发现热带地区稀有种的CNDD强于温带地区，CNDD与物种丰度的关系随纬度变化，揭示了温带与热带群落之间物种多样性维持相关的局地尺度生物相互作用的本质区别。
Theory predicts that higher biodiversity in the tropics is maintained by specialized interactions among plants and their natural enemies that result in conspecific negative density dependence (CNDD). By using more than 3000 species and nearly 2.4 million trees across 24 forest plots worldwide, we show that global patterns in tree species diversity reflect not only stronger CNDD at tropical versus temperate latitudes but also a latitudinal shift in the relationship between CNDD and species abundance. CNDD was stronger for rare species at tropical versus temperate latitudes, potentially causing the persistence of greater numbers of rare species in the tropics. Our study reveals fundamental differences in the nature of local-scale biotic interactions that contribute to the maintenance of species diversity across temperate and tropical communities.
13 Country-specific effects of neonicotinoid pesticides on honey bees and wild bees
B. A. Woodcock, J. M. Bullock, R. F. Shore… S. Knäbe, R. F. Pywell
Neonicotinoid seed dressings have caused concern world-wide. We use large field experiments to assess the effects of neonicotinoid-treated crops on three bee species across three countries (Hungary, Germany, and the United Kingdom). Winter-sown oilseed rape was grown commercially with either seed coatings containing neonicotinoids (clothianidin or thiamethoxam) or no seed treatment (control). For honey bees, we found both negative (Hungary and United Kingdom) and positive (Germany) effects during crop flowering. In Hungary, negative effects on honey bees (associated with clothianidin) persisted over winter and resulted in smaller colonies in the following spring (24% declines). In wild bees (Bombus terrestris and Osmia bicornis), reproduction was negatively correlated with neonicotinoid residues. These findings point to neonicotinoids causing a reduced capacity of bee species to establish new populations in the year following exposure.
14 Chronic exposure to neonicotinoids reduces honey bee health near corn crops
N. Tsvetkov, O. Samson-Robert, K. Sood1, H. S. Patel, D. A. Malena, P. H. Gajiwala, P. Maciukiewicz, V. Fournier, A. Zayed
Experiments linking neonicotinoids and declining bee health have been criticized for not simulating realistic exposure. Here we quantified the duration and magnitude of neonicotinoid exposure in Canada’s corn-growing regions and used these data to design realistic experiments to investigate the effect of such insecticides on honey bees. Colonies near corn were naturally exposed to neonicotinoids for up to 4 months—the majority of the honey bee’s active season. Realistic experiments showed that neonicotinoids increased worker mortality and were associated with declines in social immunity and increased queenlessness over time. We also discovered that the acute toxicity of neonicotinoids to honey bees doubles in the presence of a commonly encountered fungicide. Our work demonstrates that field-realistic exposure to neonicotinoids can reduce honey bee health in corn-growing regions.
15 Click chemistry enables preclinical evaluation of targeted epigenetic therapies
Dean S. Tyler, Johanna Vappiani, Tatiana Cañeque…Paola Grandi, Mark A. Dawson
The success of new therapies hinges on our ability to understand their molecular and cellular mechanisms of action. We modified BET bromodomain inhibitors, an epigenetic-based therapy, to create functionally conserved compounds that are amenable to click chemistry and can be used as molecular probes in vitro and in vivo. We used click proteomics and click sequencing to explore the gene regulatory function of BRD4 (bromodomain containing protein 4) and the transcriptional changes induced by BET inhibitors. In our studies of mouse models of acute leukemia, we used high-resolution microscopy and flow cytometry to highlight the heterogeneity of drug activity within tumor cells located in different tissue compartments. We also demonstrate the differential distribution and effects of BET inhibitors in normal and malignant cells in vivo. This study provides a potential framework for the preclinical assessment of a wide range of drugs.
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