A yolk–shell Sn@C nanobox composite with controllable structures has been synthesized using a facile approach. The void space is engineered to fit the volume expansion of Sn during cycling. It is ...demonstrated that the shell thickness of carbon nanobox has substantial influence on both nanostructures and the electrochemical performance. With an optimized shell thickness, a high reversible capacity of 810 mA h g−1 can be maintained after 500 cycles, corresponding to 90% retention of the second discharge capacity. For Sn@C materials with either thinner or thicker carbon shells, significant capacity decay or a decreased specific capacity are observed during cycling. The present study sheds light on the rational design of nanostructured electrode materials with enhanced electrochemical performance for next‐generation lithium ion batteries.
A novel yolk–shell Sn@C nanobox composite with controllable structures has been synthesized using a facile approach. The generation of metallic Sn together with the void space and the conversion of polymer to carbon are simultaneously completed in one step. Importantly, with an optimized carbon shell thickness, the composite exhibits high specific capacity, good rate performance, and exceptional cycling stability.
The electrochemical performance of lithium–oxygen (Li–O2) batteries awaits dramatic improvement in the design of porous cathode electrodes with sufficient spaces to accommodate the discharge products ...and discovery of effective cathode catalysts to promote both oxygen reduction reactions and oxygen evolution reactions. Herein, we report the synthesis of porous graphene with different pore size architectures as cathode catalysts for Li–O2 batteries. Porous graphene materials exhibited significantly higher discharge capacities than that of nonporous graphene. Furthermore, porous graphene with pore diameter around 250 nm showed the highest discharge capacity among the porous graphene with the small pores (about 60 nm) and large pores (about 400 nm). Moreover, we discovered that addition of ruthenium (Ru) nanocrystals to porous graphene promotes the oxygen evolution reaction. The Ru nanocrystal-decorated porous graphene exhibited an excellent catalytic activity as cathodes in Li–O2 batteries with a high reversible capacity of 17 700 mA h g–1, a low charge/discharge overpotential (about 0.355 V), and a long cycle life up to 200 cycles (under the curtaining capacity of 1000 mAh g–1). The novel porous graphene architecture inspires the development of high-performance Li–O2 batteries.
Synthesis of mesoporous graphene materials by soft-template methods remains a great challenge, owing to the poor self-assembly capability of precursors and the severe agglomeration of graphene ...nanosheets. Herein, a micelle-template strategy to prepare porous graphene materials with controllable mesopores, high specific surface areas and large pore volumes is reported. By fine-tuning the synthesis parameters, the pore sizes of mesoporous graphene can be rationally controlled. Nitrogen heteroatom doping is found to remarkably render electrocatalytic properties towards hydrogen evolution reactions as a highly efficient metal-free catalyst. The synthesis strategy and the demonstration of highly efficient catalytic effect provide benchmarks for preparing well-defined mesoporous graphene materials for energy production applications.
Light plays a pivotal role in the regulation of affective behaviors. However, the precise circuits that mediate the impact of light on depressive-like behaviors are not well understood. Here, we show ...that light influences depressive-like behaviors through a disynaptic circuit linking the retina and the lateral habenula (LHb). Specifically, M4-type melanopsin-expressing retinal ganglion cells (RGCs) innervate GABA neurons in the thalamic ventral lateral geniculate nucleus and intergeniculate leaflet (vLGN/IGL), which in turn inhibit CaMKIIα neurons in the LHb. Specific activation of vLGN/IGL-projecting RGCs, activation of LHb-projecting vLGN/IGL neurons, or inhibition of postsynaptic LHb neurons is sufficient to decrease the depressive-like behaviors evoked by long-term exposure to aversive stimuli or chronic social defeat stress. Furthermore, we demonstrate that the antidepressive effects of light therapy require activation of the retina-vLGN/IGL-LHb pathway. These results reveal a dedicated retina-vLGN/IGL-LHb circuit that regulates depressive-like behaviors and provide a potential mechanistic explanation for light treatment of depression.
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•Activation of LHb-projecting vLGN/IGL neurons inhibits neuronal activity in the LHb•M4-type mRGCs directly innervate the vLGN/IGL-LHb pathway•Activation of the retina-vLGN/IGL-LHb pathway decreases depressive-like behaviors•Light therapy ameliorates depressive symptoms via the retina-vLGN/IGL-LHb pathway
Huang et al. identified a visual circuit related to the LHb that regulates depressive-like behaviors. They demonstrate that activation of the disynaptic retina-vLGN/IGL-LHb pathway underlies the antidepressive effects of light therapy.
Novel carbon materials derived from metal‐organic frameworks (MOFs) have attracted much attention, but the commonly inevitable inward contraction during the carbonization process has restricted their ...structural variety and applications. In this work, a novel rigid‐interface induced outward contraction approach is reported for synthesizing hollow mesoporous carbon nanocubes (HMCNCs) by using ZIF‐8 nanocubes as precursors. HMCNCs exhibit a cubic morphology with the particle sizes slightly larger than ZIF‐8 nanocubes. Due to the unique outward contraction process, uniform carbon nanocubes with a hollow cavity, an outer microporous shell, and an inner mesoporous wall are simultaneously formed with a large pore size (25 nm), high surface area (1085.7 m2 g−1), high porosity (3.77 cm3 g−1), and high nitrogen content (12.2%). When used as a cathode material for Li–SeS2 batteries, the HMCNCs deliver a stable capacity of 812.6 mA h g−1 at 0.2 A g−1 after 100 cycles and an outstanding rate capability (455.1 mA h g−1 at 5.0 A g−1). The findings may pave the way for the construction of distinctive MOF‐derived carbon materials for various applications.
Metal‐organic framework (MOF)‐derived hollow mesoporous carbon nanocubes (HMCNCs) with a uniform nanocubic morphology, a large hollow cavity, an outer microporous shell, and an inner mesoporous shell are synthesized via a novel rigid‐interface induced outward contraction approach. When used as a cathode substrate for Li–SeS2 batteries, HMCNCs deliver superior electrochemical performances with stable capacity and outstanding rate capability.
Studies of genetic adaptation, a central focus of evolutionary biology, most often focus on the host’s genome and only rarely on its co-evolved microbiome. The Qinghai-Tibetan Plateau (QTP) offers ...one of the most extreme environments for the survival of human and other mammalian species. Yaks (Bos grunniens) and Tibetan sheep (T-sheep) (Ovis aries) have adaptations for living in this harsh high-altitude environment, where nomadic Tibetan people keep them primarily for food and livelihood 1. Adaptive evolution affects energy-metabolism-related genes in a way that helps these ruminants live at high altitude 2, 3. Herein, we report convergent evolution of rumen microbiomes for energy harvesting persistence in two typical high-altitude ruminants, yaks and T-sheep. Both ruminants yield significantly lower levels of methane and higher yields of volatile fatty acids (VFAs) than their low-altitude relatives, cattle (Bos taurus) and ordinary sheep (Ovis aries). Ultra-deep metagenomic sequencing reveals significant enrichment in VFA-yielding pathways of rumen microbial genes in high-altitude ruminants, whereas methanogenesis pathways show enrichment in the cattle metagenome. Analyses of RNA transcriptomes reveal significant upregulation in 36 genes associated with VFA transport and absorption in the ruminal epithelium of high-altitude ruminants. Our study provides novel insights into the contributions of microbiomes to adaptive evolution in mammals and sheds light on the biological control of greenhouse gas emissions from livestock enteric fermentation.
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•High-altitude adaptation produces convergent phenotypes of rumen metabolism•Microbial community structures and compositions contribute to convergent adaptation•Results show convergence of microbial genes in VFAs and methane-yielding pathways•Microbiomes co-evolve with host genomes for extremely environmental adaptation
Zhang et al. observe both low-methane emissions and high-VFA production in high-altitude mammals. Using ultra-deep metagenomic sequencing, the authors show co-enrichment in VFA-yielding pathways of rumen microbial genes in high-altitude species, suggesting convergent evolution of rumen microbiomes for their hosts’ energy harvesting persistence.
Silicon has been recognized as the most promising anode material for high capacity lithium ion batteries. However, large volume variations during charge and discharge result in pulverization of Si ...electrodes and fast capacity loss on cycling. This drawback of Si electrodes can be overcome by combination with well-organized graphene foam. In this work, hierarchical three-dimensional carbon-coated mesoporous Si nanospheres@graphene foam （C@Si@GF） nanoarchitectures were successfully synthesized by a thermal bubble ejection assisted chemical-vapor-deposition and magnesiothermic reduction method. The morphology and structure of the as-prepared nanocomposites were characterized by field emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. When employed as anode materials in lithium ion batteries, C@Si@GF nanocomposites exhibited superior electrochemical per- formance including a high specific capacity of 1,200 mAh/g at the current density of 1A/g, excellent high rate capabilities and an outstanding cyclability. Post-mortem analyses identified that the morphology of 3D C@Si@GF electrodes after 200 cycles was well maintained. The synergistic effects arising from the combination of mesoporous Si nanospheres and graphene foam nanoarchitectures may address the intractable pulverization problem of Si electrode.
Summary
Despite their important roles in host nutrition, metabolism and adaptability, the knowledge on how the mammalian gut microbial community assemble is relatively scanty, especially regarding ...the ecological mechanisms that govern microbiota along environmental gradients. To address this, we surveyed the diversity, function and ecological processes of gut microbiota in the wild plateau pika, Ochotona curzoniae, along the elevational gradient from 3106 to 4331 m on ‘the Roof of the World’—Qinghai‐Tibet Plateau. The results indicated that the alpha, beta and functional diversity of gut microbiota significantly increased with elevation, and elevation significantly explained the variations in the gut microbial communities, even after controlling for geographical distance, host sex and body weight. Some gene functions (e.g. nitrogen metabolism and protein kinases) associated with metabolism were enriched in the high‐altitude pikas. Null model and phylogenetic analysis suggest that the relative contributions of environmental filtering responsible for local gut communities increased with elevation. In addition, deterministic processes dominated gut microbial communities in the high‐altitude (more than 3694 m) pikas, while the percentages of stochastic and deterministic processes were very close in the low‐altitude (3106 and 3580 m) pikas. The observed mechanisms that influence pika gut microbiota assembly and function seemed to be mainly mediated by the internal gut environment and by the external environmental pressure (i.e. lower temperature) in the harsh high‐altitude environment. These findings enhance our understanding of gut microbiota assembly patterns and function in wild mammals from extreme harsh environments.
The relative contributions of environmental filtering responsible for local gut communities increased with elevation. In addition, deterministic processes dominated gut microbial communities in the high‐altitude (more than 3694 m) pikas, while the percentages of stochastic and deterministic processes were very close in the low‐altitude (3106 and 3580 m) pikas.
In this study, a fluorine-containing flow modifier (Si-DF) with low surface energy is successfully synthesized, which is applied to fabricate ideal electronic packaging materials (BN/PPS composites) ...with high thermal conductivity, excellent dielectric properties, processability, and toughness by conventional melt blending. Si-DPF is located at the interface between the BN fillers and the PPS matrix, which not only improves the dispersion of BN fillers but also strengthens the interaction. With the help of 5 wt% Si-DF,
still exhibits the high thermally conductive coefficient (3.985 W/m·K) and low dielectric constant (3.76 at 100 MHz) although BN fillers are loaded as high as 70 wt%. Moreover, the sample processes a lower stable torque value (2.5 N·m), and the area under the stress-strain curves is also increased. This work provides an efficient way to develop high-performance polymer-based composites with high thermally conductive coefficients and low dielectric constants for electronic packaging applications.
Light exerts profound effects on cognitive functions across species, including humans. However, the neuronal mechanisms underlying the effects of light on cognitive functions are poorly understood. ...In this study, we show that long-term exposure to bright-light treatment promotes spatial memory through a di-synaptic visual circuit related to the nucleus reuniens (Re). Specifically, a subset of SMI-32-expressing ON-type retinal ganglion cells (RGCs) innervate CaMKIIα neurons in the thalamic ventral lateral geniculate nucleus and intergeniculate leaflet (vLGN/IGL), which in turn activate CaMKIIα neurons in the Re. Specific activation of vLGN/IGL-projecting RGCs, activation of Re-projecting vLGN/IGL neurons, or activation of postsynaptic Re neurons is sufficient to promote spatial memory. Furthermore, we demonstrate that the spatial-memory-promoting effects of light treatment are dependent on the activation of vLGN/IGL-projecting RGCs, Re-projecting vLGN/IGL neurons, and Re neurons. Our results reveal a dedicated subcortical visual circuit that mediates the spatial-memory-promoting effects of light treatment.
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•Activation of Re-projecting vLGN/IGL neurons activates neuronal activity in the Re•SMI-32+ ON-type RGCs directly innervate the vLGN/IGL-Re pathway•Activation of the retina-vLGN/IGL-Re pathway promotes spatial memory•Light treatment promotes spatial memory via the retina-vLGN/IGL-Re pathway
Huang et al. identified a visual circuit related to the Re that regulates spatial memory. They demonstrate that the retina-vLGN/IGL-Re pathway mediates the spatial-memory-promoting effects of light treatment.
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