摘要：The anionic redox chemistry(O^2-→O^-)in P2-type sodium-ion battery cathodes has attracted much ***,determining how to tune the anionic redox reaction is still a major ***,we tune the activity and reversibility of both the anionic and cationic redox reactions of Na0.67Mn0.5Fe0.5O2 though an integrated strategy that combines the advantages of Li2SiO3 coating,Li doping and Si doping,and the initial capacity,rate performance and cycling stability are significantly *** in-depth modulation mechanism is revealed by means of neutron diffraction,X-ray absorption spectroscopy,in situ X-ray diffraction,electron paramagnetic resonance spectroscopy,first-principles calculations and so *** Li2SiO3 coating alleviates the side reactions and enhances the cycling ***^4+doping lowers the Na^+diffusion barrier due to the expanded interlayer ***,Si^4+doping improves the structural stability,oxygen redox activity and ***^+doping in Na sites further increases the structure *** electron density maps confirm the greater activity of Na and O in the modified *** density maps and bond-valence energy landscapes identify the Na^+migration pathway from Nae site to Naf site(the positions of the Na ions in the crystal structure).The proposed insights into the modulation mechanism of the anionic and cationic redox chemistry are also instructive for designing other oxide-based cathode materials.

摘要：Flow rate and temperature are important parameters for design and operation of liquid lead–bismuth(Pb Bi) experimental loop. The PREKY facility was designed to study test technique of flow rate and local temperature of Pb Bi loop. In this work, flow rate monitoring of molten Pb Bi was performed, and temperatures of the Pb Bi and pipe surface were measured. The results show that the flow rate of the venturi-nozzle flow meter had an uncertainty of ±5 % in the range of 0.6–2.0 m/s, and the maximum temperature difference between the Pb Bi and pipe surface was about 8 ℃.

摘要：Hamamatsu R1924A is one of the most widely used photomultiplier tubes(PMTs) in nuclear *** the active base suitable for R1924A is still not available in market, an active base is designed for Hamamatsu R1924A PMT, and the test results at high counting rates are presented. The active bases with two different sets of resistor chains were tested and compared by a frequency-controlled green straw hat LED light. A stable signal output up to 100 kHz is achieved using frequency-controlled LED pulsed light. The temperature of bases, which reflects the power consumption and is crucial for applications in vacuum, is also monitored with the same LED pulsed light. The temperature of the active base with smaller resistances reaches about twice of that of the active base with larger resistances in the resistor chain. For the applications in vacuum, the active base with resistance between the two sets of resistor chains may be preferable.

摘要：Metabolites play important roles in numerous cell biology processes,such as cell proliferation,differentiation,stress response,and cell death[1].Recently,lactate and lactate-derived lysine residue lactylation(Kla)have emerged as newly discovered epigenetic modifications that play critical roles in various physiological and pathological *** the history of lactate research,we can categorize the studies into three mile stones(Fig.S1 online).

摘要：Rapid growth in population and gross domestic product in chinese urban regions such as Beijing has resulted in a large amount of CO2 emissions from fossil fuels. Forests are considered the most important carbon sink to offset these carbon emissions. In this study we estimated forest carbon storage in Beijing using forest inventory data and the biomass expansion factors method. We analyzed trends in the forest ecosystem and its fractions along altitudinal gradients. We concluded that broad-leaved forest is the main forest carbon pool in Beijing, and forest carbon is mainly stored in plains at an altitude of＆lt;60 m a.s.l. and in the low mountainous area at an altitude of 60-600 m a.s.l. Forest ecosystem carbon density in Beijing increases with altitudinal gradients but slightly decreases in regions at altitudes that range from 200-400 m a.s.l. Forest vegetation carbon density of the plain area at an altitude of ＆lt;60 m a.s.l. is much higher than other areas, attributable to the high ratios of the plantation of Populus spp. and Larix principisrupprechtii with higher vegetation carbon densities than others and human practices such as fertilization and irrigation which are beneifcial for vegetation carbon accumulation. The forest soil carbon density in Beijing also increases with increasing altitude, attributable to decreasing soil carbon output with altitude. Management practices such as understory cultivation, irrigation, fertilization and scariifcation directly accelerate carbon emissions from soil heterotrophic respiration which decreases with altitude. Soil erosion in areas that range from 200-800 m a.s.l. also decrease with altitude as management practices decrease. This study will underpin scientiifc knowledge for local forest managers to adopt more appropriate practices to protect forest ecosystems and to improve forest carbon storage.

摘要：We propose a new 3D inversion scheme to invert the near-and transition-zone data of CSAMT with topography *** this new method,the earth was discretized into unstructured tetrahedra to fit the ragged topography and the vector fi nite-element method was adopted to obtain precise responses and good *** simulate the attitude and shape of the transmitter,we divided a long-grounded transmitter into dipoles and integrated these dipoles to obtain good responses in the near-and transition-fi eld ***,we designed an L2 norm-based objective functional and applied a standard quasi-Newton method as the optimization method to solve the inverse problem and guarantee steady *** tested our 3D inversion method first on synthetic data and then on a field dataset acquired from select sites near Changbai Mountain,*** both tests,the new inversion algorithm achieved excellent fitting between the predicted and observed data,even in near-and transition-fi eld zones,and the inversion results agreed well with the true *** fi ndings reveal that the proposed algorithm is eff ective for 3D inversion of CSAMT data.

摘要：Electrochemical CO2 reduction reaction(CO2RR)powered by renewable electricity has emerged as the most promising technique for CO2 conversion,making it possible to realize a carbon‐neutral *** efficient,robust,and cost‐effective catalysts are highly demanded for the near‐future practical applications of *** studies on atomically dispersed metal‐nitrogen(M‐Nx)sites constituted of earth abundant elements with maximum atom‐utilization efficiency have demonstrated their performance towards *** review summarizes recent advances on a variety of M‐Nx sites‐containing transition metal‐centered macrocyclic complexes,metal organic frameworks,and M‐Nx‐doped carbon materials for efficient CO2RR,including both experimental and theoretical *** roles of metal centers,coordinated ligands,and conductive supports on the intrinsic activity and selectivity,together with the importance of reaction conditions for improved performance are *** mechanisms of CO2RR over these M‐Nx‐containing materials are presented to provide useful guidance for the rational design of efficient catalysts towards CO2RR.

摘要：Burning crop residues and excessive use of chemical fertilizers results in an enormous waste of bio- logical resources, which further weakens the potential capacity of the agro-ecosystem as a carbon sink. To explore the potential of farmlands acting as a carbon sink without yield losses, we conducted an experiment on a temperate eco-farm in eastern rural China. Crop residues were applied to cattle feed, and the composted cattle manure was returned to cropland with a winter wheat and maize rotation. Four different proportions of fertilizers were designed： 100 % cattle manure, 100 % mineral nitrogen, 75 % cattle manure plus 25 % mineral nitrogen, and 50 % cattle manure plus 50 % mineral nitrogen. Crop yield and greenhouse gas （GHG） emissions were carefully calculated according to the Intergovernmental Panel on Climate Change （IPCC） Guidelines for National Green- house Gas Inventories 2006. Our results showed that replacing chemical fertilizer with organic manure signifi- cantly decreased the emission of GHGs. Yields of wheat and corn also increased as the soil fertility was improved by the application of cattle manure. Totally replacing chemical fertilizer with organic manure decreased GHG emissions, which reversed the agriculture ecosystem from a carbon source （＋2.7 t CO_2-eq. hm-2 year-1） to a carbon sink （-8.8 t CO_2-eq. hm^-2 year^-1）. Our findings provide useful insights for improving agricultural ecosystems under global change scenarios.

摘要：近年来,纳米尺度上范德华材料中声子极化激元的研究因在纳米光子学中的潜在应用而受到广泛关注.这些材料具有亚衍射分辨成像和传感的独特能力,因而成为纳米光子学领域新技术开发的热门途径.尽管声子极化激元材料的研究取得了很多进展,但由于这些材料的绝缘特性,其在实现声子极化激元的动态可逆操纵方面仍然存在挑战.最新研究发现,借助VO_(2)薄膜,可以实现α-MoO_(3)中各向异性声子极化激元的可逆操纵.VO_(2)薄膜是一种近室温相变材料,因其相变前后绝缘态和金属态之间介电性能的巨大变化受到广泛关注.最新的一项研究展示了精心构建的α-MoO_(3)/VO_(2)异质结构,改变温度调控VO_(2)薄膜的介电性能,能够调谐中红外波段极化激元的传播.这些结果展示了一种在纳米尺度上控制光能流动的有效方法,并为集成平面亚衍射激元器件的设计和制造提供了指导.

摘要：镁二次电池具有安全性高、价格低廉等优点,是一种具有潜在应用前景的高能量密度电池体系.目前,镁二次电池的研究重点之一是寻找合适的电极材料.最近,我们通过水热和热处理相结合的方法成功制备了具有三维导电网络结构的锡纳米颗粒/石墨烯纳米片复合电极材料.研究发现,在石墨烯的三维导电网络片层上,均匀分布了粒径小于100 nm的锡纳米颗粒.将锡纳米颗粒/石墨烯纳米片复合材料作为镁二次电池电极材料,当电流密度为15 mA·g^(-1)和300 mA·g^(-1)时,首次放电容量分别达到了545.4 mAh·g^(-1)和238.8 mAh·g^(-1),经过150圈后,容量保持率达到了93%,库伦效率为99%,表现出了较高的电化学活性.研究还发现,镁离子嵌入复合材料中形成镁锡合金,当镁离子脱出后,再次形成锡纳米颗粒/石墨烯纳米片复合电极材料,镁离子的脱出和嵌入具有很高的可逆性.这对未来研究设计高性能镁离子电极材料具有十分重要的意义.