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Astrocytic modulation of potassium under seizures 预览
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作者 Fushun Wang Xiaoming Qi +1 位作者 Jun Zhang Jason HHuang 《中国神经再生研究:英文版》 SCIE CAS CSCD 2020年第6期980-987,共8页
The contribution of an impaired astrocytic K^+ regulation system to epileptic neuronal hyperexcitability has been increasingly recognized in the last decade.A defective K^+ regulation leads to an elevated extracellula... The contribution of an impaired astrocytic K^+ regulation system to epileptic neuronal hyperexcitability has been increasingly recognized in the last decade.A defective K^+ regulation leads to an elevated extracellular K^+ concentration([K^+]o).When[K^+]o reaches peaks of 10-12 mM,it is strongly associated with seizure initiation during hypersynchronous neuronal activities.On the other hand,reactive astrocytes during a seizure attack restrict influx of K^+ across the membrane both passively and actively.In addition to decreased K^+ buffering,aberrant Ca^2+ signaling and declined glutamate transport have also been observed in astrogliosis in epileptic specimens,precipitating an increased neuronal discharge and induction of seizures.This review aims to provide an overview of experimental findings that implicated astrocytic modulation of extracellular K^+ in the mechanism of epileptogenesis. 展开更多
关键词 AQP4 Ca^2+ signaling cell volume CONNEXINS EPILEPSY K^+ buffering mi RNA NKCC PANNEXIN TBI
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Effects of V-pits covering layer position on the optoelectronic performance of InGaN green LEDs 预览
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作者 Chen Xu Changda Zheng +4 位作者 Xiaoming Wu Shuan Pan Xingan Jiang Junlin Liu Fengyi Jiang 《半导体学报:英文版》 EI CAS CSCD 2019年第5期61-65,共5页
The impact of the V-pits covering layer(VCL) position on the optoelectronic performance of InGaN-based green light-emitting diodes(LEDs) was investigated. It is found that earlier covering of V-pits will hinder the ho... The impact of the V-pits covering layer(VCL) position on the optoelectronic performance of InGaN-based green light-emitting diodes(LEDs) was investigated. It is found that earlier covering of V-pits will hinder the hole injection via the sidewall of V-pits, and then result in less quantum wells(QWs) participating in radioluminescence. The current-voltage characteristics show that the LEDs with earlier covering of V-pits have higher operating voltage at room temperature, and a more dramatic voltage rise with the reduction of temperature. Meanwhile, more manifested emission peaks for sidewall QWs and deeper QWs near to ntype layer was observed in the sample with earlier coveing of V-pits at cryogenic temperatures, for the reason that the holes being injected via V-pits sidewall have higher kinetic energy and could transport to deeper QWs. 展开更多
关键词 green LIGHT-EMITTING DIODES V-pits covering layer hole injection efficiency operating voltage
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Fish Assemblage Responses to a Low-head Dam Removal in the Lancang River 预览
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作者 DING Chengzhi JIANG Xiaoming +11 位作者 WANG Lieen FAN Hui CHEN Liqiang HU Jinming WANG Hailong CHEN Yifeng SHI Xiaotao CHEN Hao PAN Bohui DING Liuyong ZHANG Chao HE Daming 《中国地理科学:英文版》 SCIE CSCD 2019年第1期26-36,共11页
Dam removal is becoming an effective approach for aquatic biodiversity restoration in damming river in order to balance the aquatic ecosystem conservation with large-scale cascade damming. However, the effects of dam ... Dam removal is becoming an effective approach for aquatic biodiversity restoration in damming river in order to balance the aquatic ecosystem conservation with large-scale cascade damming. However, the effects of dam removal on fish communities in Asian mountainous rivers, which are dominated by Cypriniformes fishes, are still not well known. To determine whether dam removal on a mountainous river benefit restoration of fish diversity, we investigated the response of fish assemblage to dam removal using a before-after-control-impact design in two tributaries of the Lancang River(dam removal river: the Jidu River, and control river: the Fengdian River). Fish surveys were conducted one year prior to dam removal(2012) and three years(2013–2015) following dam removal. We observed rapidly and notably spatio-temporal changes in fish biodiversity metrics and assemblage structure, occurring in the Jidu River within the first year after dam removal. Overall, fish species richness, density and Shannon-Wiener diversity all increased immediately in above-and below-dam sites, and maintained a stable level in subsequent years, compared to unchanged situation in the control river. All sites in the Jidu River experienced shifts in fish composition after dam removal, with the greatest temporal changes occurred in sites below-and above-the former dam, resulting in a temporal homogenization tendency in the dam removed river. These findings suggest that dam removal can benefit the recovery of habitat conditions and fish community in Asian mountainous rivers, but the results should be further evaluated when apply to other dammed rivers since the dam age, fluvial geomorphology and situation of source populations could all affect the responses of fish assemblages. 展开更多
关键词 fish diversity DAM DEMOLITION HABITAT recovery CYPRINIFORMES international RIVERS
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Phase–amplitude model for doubly fed induction generators 预览
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作者 Hua HUANG Ping JU +3 位作者 Xueping PAN Yuqing JIN Xiaoming YUAN Yuan GAO 《现代电力系统与清洁能源学报(英文)》 CSCD 2019年第2期369-379,共11页
The doubly fed induction generator(DFIG) is major type of wind turbine generator used in grid-connected wind farms. Practical models of DFIG have been built to study the influence of wind power generation on power sys... The doubly fed induction generator(DFIG) is major type of wind turbine generator used in grid-connected wind farms. Practical models of DFIG have been built to study the influence of wind power generation on power system dynamics. However, most existing practical models of the DFIG are based on rectangular coordinates,in which frequency variation is neglected. In this paper, a phase-amplitude(P-A) model is proposed for a DFIG based on phase and amplitude of the internal voltage. The model structure is much like that of the synchronous generator, and the rotor voltage can manipulate both the amplitude and the phase of the internal voltage.Comparisons have been made between the new P-A model of the DFIG and the synchronous generator model,as well as the asynchronous motor model.The contributions of the new P-A model of the DFIG are discussed and it is demonstrated that the proposed model has better ability in describing power system dynamic phenomena such as voltage dynamics and structural dynamics. Simulation results and a field test validate these contributions. 展开更多
关键词 DOUBLY fed induction generator(DFIG) MODEL Internal VOLTAGE VOLTAGE DYNAMICS Frequency DYNAMICS
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行波管金刚石输能窗片金属化影响因素分析 预览
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作者 薛辽豫 刘林 +2 位作者 张平伟 安晓明 刘青伦 《电子元件与材料》 CAS CSCD 北大核心 2019年第1期83-88,共6页
为制备行波管用金刚石输能窗片,分析金刚石金属化影响因素。采用粗糙度、拉曼光谱评估金刚石材料性能。采用酸洗、离子束刻蚀清洗金刚石表面。采用冲压掩膜、光刻掩膜防护非金属化区域。通过物理气相沉积制备Ti/Mo/Ni金属化层,并通过真... 为制备行波管用金刚石输能窗片,分析金刚石金属化影响因素。采用粗糙度、拉曼光谱评估金刚石材料性能。采用酸洗、离子束刻蚀清洗金刚石表面。采用冲压掩膜、光刻掩膜防护非金属化区域。通过物理气相沉积制备Ti/Mo/Ni金属化层,并通过真空热处理方法制备TiC过渡层。结果表明:当金刚石内石墨的质量分数低于1%时,离子束刻蚀方法一方面去除金刚石表面杂质,另一方面将表面粗糙度从0.256μm提升至0.343μm;相比冲压掩模,光刻掩模降低界面孔隙率,减少了金属离子对掩模底层的污染,过渡区域宽度从200μm减少至10μm;700℃保温过程促进了TiC的形成,提升了金属化层结合强度,促进了抗热冲击性能。 展开更多
关键词 金刚石 金属化 物理气相沉积 掩膜 热处理 碳化钛
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East Asian Economic Integration under the US Protectionist Trade Policy 预览
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作者 Pan Xiaoming 《中国国际问题研究:英文版》 2019年第5期90-104,共15页
In pursuit of“America First,”the Trump administration has adopted a protectionist trade policy in an attempt to strengthen the competitive advantage of US companies,and has invoked domestic law to impose tariffs on ... In pursuit of“America First,”the Trump administration has adopted a protectionist trade policy in an attempt to strengthen the competitive advantage of US companies,and has invoked domestic law to impose tariffs on trading partners,with the intent of forcing other countries to adjust their trade policies in a direction more favorable to the US. 展开更多
关键词 COMPANIES TRADING PARTNER
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Statistical study on interplanetary drivers behind intense geomagnetic storms and substorms 预览
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作者 Tian Tian Zheng Chang +3 位作者 LingFeng Sun JunShui Bai XiaoMing Sha Ze Gao 《地球与行星物理:英文版》 CSCD 2019年第5期380-390,共11页
Geomagnetic storms and substorms play a central role in both the daily life of mankind and in academic space physics.The profiles of storms,especially their initial phase morphology and the intensity of their substorm... Geomagnetic storms and substorms play a central role in both the daily life of mankind and in academic space physics.The profiles of storms,especially their initial phase morphology and the intensity of their substorms under different interplanetary conditions,have usually been ignored in previous studies.In this study,97 intense geomagnetic storms(Dstmin≤–100 nT)between 1998 and 2018 were studied statistically using the double superposed epoch analysis(DSEA)and normalized superposed epoch analysis(NSEA)methods.These storms are categorized into two types according to different interplanetary magnetic field(IMF)Bz orientations:geomagnetic storms whose IMF is northward,both upstream and downstream relative to the interplanetary shock,and geomagnetic storms whose upstream and downstream IMF is consistently southward.We further divide these two types into two subsets,by different geomagnetic storm profiles:Type Ⅰ/Type Ⅱ—one/two-step geomagnetic storms with northward IMF both upstream and downstream of the interplanetary shock;Type Ⅲ/TypeⅣ—one/two-step geomagnetic storms with southward IMF both upstream and downstream of the interplanetary shock.The results show that:(1)geomagnetic storms with northward IMF both upstream and downstream of the interplanetary shock have a clear initial phase;geomagnetic storms with southward IMF in both upstream and downstream of the interplanetary shock do not;(2)the IMF is an important controlling factor in affecting the intensity characteristics of substorms.When Bz is positive before and after the interplanetary shock arrival,the Auroral Electrojet(AE)index changes gently during the initial phase of geomagnetic storms,the median value of AE index is maintained at 500–1000 nT;(3)when Bz is negative before and after the interplanetary shock arrival,the AE index rises rapidly and reaches its maxmum value about one hour after storm sudden commencements(SSC),although the time is scaled between reference points and the maximum value of AE is usually greater than 1,000 nT 展开更多
关键词 GEOMAGNETIC storms SUBSTORMS normalized superposed EPOCH analysis initial phase IMF Bz
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Magnetically Driven Superhydrophobic Polyurethane Sponge for High Efficiency Oil/Water Mixtures Separation
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作者 Xuemei Zhang Feng Fu +1 位作者 Xiaoming Gao Xiufang Hou 《仿生工程学报:英文版》 SCIE EI CSCD 2019年第1期38-46,共9页
Magnetically driven super-hydrophobic materials were prepared by Fe3O4 nanoparticles and stearic acid,which were deposited on the surface of polyurethane sponges.The presence of the Fe3O4 nanoparticles makes the spong... Magnetically driven super-hydrophobic materials were prepared by Fe3O4 nanoparticles and stearic acid,which were deposited on the surface of polyurethane sponges.The presence of the Fe3O4 nanoparticles makes the sponge have the magnetic,and the micro-nano hierarchical structure and hydrophobic functional groups lead to the sponge have excellent superhydrophobicity.The as-prepared sponge exhibited excellent absorption capacities for various oils and organic solvents ranging from 23.8 times to 86.7 times of its own weight.Moreover,the oil separation capacities still keep a high value after 50 cycles of squeezing the saturated absorbed as-prepared sponge.All of these satisfactory properties make the as-prepared sponge as a candidate of ideal absorbents for oily industrial wastewater and oil spills in oceans. 展开更多
关键词 superhydrophobic/superoleophilic materials POLYURETHANE SPONGE magnetic DRIVEN oil-water SEPARATION continuous SEPARATION
Self-ignition characteristics of the high-speed ramjet kinetic energy projectile in the launch process
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作者 Changfei ZHUO Haotian CHEN +1 位作者 Wenjin YAO Xiaoming WANG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第4期851-860,共10页
To research the self-ignition characteristics of high-speed ramjet kinetic energy projectile in the launch process, the self-ignition process based on the solid fuel of polyethylene was numerically simulated by using ... To research the self-ignition characteristics of high-speed ramjet kinetic energy projectile in the launch process, the self-ignition process based on the solid fuel of polyethylene was numerically simulated by using the dynamic grid technology. The effect of different muzzle velocity on the self-ignition performance, and the effect of opening the blockage at different times on the flow field stability of the combustion chamber and the flow field characteristics after the solid fuel ramjet stabilized were analyzed. The results show that the occurrence of self-ignition is not only related to the pressure, temperature in the combustion chamber, and the muzzle velocity, but also to the content of C2H4 and its degree of mixing with air in the combustion chamber. After the kinetic energy projectile gets out of the muzzle and before the blockage opens, there is oscillation occurring in the combustion chamber. The higher the muzzle velocity of the kinetic energy projectile, the more prone to the occurrence of the self-ignition and the negative effects can be avoided due to the pressure oscillation in the combustion chamber. The effect of opening the blockage at different times on the flow field stability after the self-ignition occurs in a period of time is weak. After the blockage opens, the solid fuel ramjet can reach a stable working condition quickly. 展开更多
关键词 Dynamic grid KINETIC energy PROJECTILE MUZZLE velocity SELF-IGNITION Solid fuel RAMJET
Effect of minor content of Gd on the mechanical and degradable properties of as-cast Mg-2Zn-xGd-0.5Zr alloys
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作者 Junxiu Chen Lili Tan +1 位作者 Xiaoming Yu Ke Yang 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第4期503-511,共9页
RE-containing Mg alloys used as biodegradable medical implants exhibit good promising application due to their good mechanical properties and degradation resistance. In this work, effect of Gd on the microstructure, m... RE-containing Mg alloys used as biodegradable medical implants exhibit good promising application due to their good mechanical properties and degradation resistance. In this work, effect of Gd on the microstructure, mechanical properties and biodegradation of as-cast Mg-2Zn-xGd-0.5Zr alloys was investigated. The results showed that there were mainly α-Mg, I-phase, W-phase and MgZn2 phase in Mg-Zn-Gd-Zr alloys. With increase of the Gd content, the strength of the alloys was enhanced due to the second phase strengthening and grain refinement. The degradation resistance of Mg-2Zn-0.5Zr alloy was increased by adding 0.5%–1% Gd due to the uniformly distributed second phases which acted as a barrier to prevent the pitting corrosion. However, increasing Gd content to 2% reduced the degradation resistance of the alloy due to the galvanic corrosion between the matrix and the second phases.The good degradation resistance and mechanical properties of as-cast Mg-2Zn-1Gd-0.5Zr alloy makes it outstanding for biomaterial application. 展开更多
关键词 Mg-2Zn-0.5Zr-Gd allo Microstructure MECHANICAL properties Biodegradation
Responses of different biodiversity indices to subsampling efforts in lotic macroinvertebrate assemblages 预览
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作者 WANG Jun LI Zhengfei +3 位作者 SONG Zhuoyan ZHANG Yun JIANG Xiaoming XIE Zhicai 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第1期122-133,共12页
As a less time-consuming procedure,subsampling technology has been widely used in biological monitoring and assessment programs.It is clear that subsampling counts affect the value of traditional biodiversity indices,... As a less time-consuming procedure,subsampling technology has been widely used in biological monitoring and assessment programs.It is clear that subsampling counts affect the value of traditional biodiversity indices,but its effect on taxonomic distinctness(TD)indices is less well studied.Here,we examined the responses of traditional(species richness,Shannon-Wiener diversity)and TD(average taxonomic distinctness:Δ^+,and variation in taxonomic distinctness:Λ^+)indices to subsample counts using a random subsampling procedure from 50 to 400 individuals,based on macroinvertebrate datasets from three different river systems in China.At regional scale,taxa richness asymptotically increased with fi xed-count size;≥250–300 individuals to express 95%information of the raw data.In contrast,TD indices were less sensitive to the subsampling procedure.At local scale,TD indices were more stable and had less deviation than species richness and Shannon-Wiener index,even at low subsample counts,with≥100 individuals needed to estimate 95%of the information of the actualΔ^+andΛ+in the three river basins.We also found that abundance had a certain effect on diversity indices during the subsampling procedure,with different subsampling counts for species richness and TD indices varying by regions.Therefore,we suggest that TD indices are suitable for biodiversity assessment and environment monitoring.Meanwhile,pilot analyses are necessary when to determine the appropriate subsample counts for bioassessment in a new region or habitat type. 展开更多
关键词 SUBSAMPLING MACROINVERTEBRATES TAXONOMIC distinctness indices TAXA richness Shannon-Wiener index
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Selectivity regulation of CO2 electroreduction through contact interface engineering on superwetting Cu nanoarray electrodes
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作者 Zhao Cai Yusheng Zhang +9 位作者 Yuxin Zhao Yueshen Wu Wenwen Xu Xuemei Wen Yang Zhong Ying Zhang Wen Liu Hailiang Wang Yun Kuang Xiaoming Sun 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第2期345-349,共5页
Electrocatalytic CO2 reduction is a promising way to mitigate the urgent energy and environmental issues, but how to increase the selectivity for desired product among multiple competi ng reaction pathways remains a b... Electrocatalytic CO2 reduction is a promising way to mitigate the urgent energy and environmental issues, but how to increase the selectivity for desired product among multiple competi ng reaction pathways remains a bottle neck. Here, we demonstrate that engineering the gas-liquid-solid contact interface on the electrode surface could tailor the selectivity of CO2 reducti on and meanwhile suppress H2 production through regulated reacti on kin etics. Specifically, polytetrafl uoroethyle ne (PTFE) was utilized to modify a Cu nano array electrode as an example, which is able to cha nge the electrode surface from aerophobic to aerophilic state. The en riched nano-tunnels of the Cu nano array electrode can facilitate CO2 transportation and pin gaseous products on the electrode surface. The latter is believed to be the reason that boosts the Faradaic efficie ncy of liquid products by 67% and limits the H2 producti on to less than half of before. This in terface engin eeri ng strategy also lowered H2O (proton) affinity, therefore promoting CO and HCOOH production. Engineering the electrode contact interface controls the reaction kinetics and the selectivity of products, which should be inspiring for other electrochemical reactions. 展开更多
关键词 CO2 REDUCTION SELECTIVITY copper contact interface reaction KINETICS
Efficient InGaN-based yellow-light-emitting diodes
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作者 FENGYI JIANG JIANLI ZHANG +10 位作者 LONGQUAN XU JIE DING GUANGXU WANG XIAOMING WU XIAOLAN WANG CHUNLAN MO ZHIJUE QUAN XING GUO CHANGDA ZHENG SHUAN PAN JUNLIN LIU 《光子学研究:英文版》 CSCD 2019年第2期144-148,共5页
Realization of efficient yellow-light-emitting diodes(LEDs) has always been a challenge in solid-state lighting.Great effort has been made, but only slight advancements have occurred in the past few decades. After com... Realization of efficient yellow-light-emitting diodes(LEDs) has always been a challenge in solid-state lighting.Great effort has been made, but only slight advancements have occurred in the past few decades. After comprehensive work on InGaN-based yellow LEDs on Si substrate, we successfully made a breakthrough and pushed the wall-plug efficiency of 565-nm-yellow LEDs to 24.3% at 20 A∕cm~2 and 33.7% at 3 A∕cm~2. The success of yellow LEDs can be credited to the improved material quality and reduced compressive strain of InGaN quantum wells by a prestrained layer and substrate, as well as enhanced hole injection by a 3 D pn junction with V-pits. 展开更多
关键词 INGAN SI EFFICIENT InGaN-based
p53 mutation regulates PKD genes and results in co-occurrence of PKD and tumorigenesis 预览
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作者 Haili Li Yongjin Zhang +8 位作者 Juhua Dan Ruoyu Zhou Cui Li Rong Li Xiaoming Wu Sanjay Kumar Singh Jeffrey T. Chang Julun Yang Ying Luo 《癌症生物学与医学:英文版》 CAS CSCD 2019年第1期79-88,共10页
Objective: Polycystic kidney disease(PKD) is the major cause of kidney failure and mortality in humans. It has always been suspected that the development of cystic kidney disease shares features with tumorigenesis, al... Objective: Polycystic kidney disease(PKD) is the major cause of kidney failure and mortality in humans. It has always been suspected that the development of cystic kidney disease shares features with tumorigenesis, although the evidence is unclear.Methods: We crossed p53 mutant mice(p53N236S, p53S) with Werner syndrome mice and analyzed the pathological phenotypes.The RNA-seq, ss GSEA analysis, and real-time PCR were performed to dissect the gene signatures involved in the development of disease phenotypes.Results: We found enlarged kidneys with fluid-filled cysts in offspring mice with a genotype of G3mTerc-/-WRN-/-p53S/S(G3TM).Pathology analysis confirmed the occurrence of PKD, and it was highly correlated with the incidence of tumorigenesis. RNA-seq data revealed the gene signatures involved in PKD development, and demonstrated that PKD and tumorigenesis shared common pathways, including complement pathways, lipid metabolism, mitochondria energy homeostasis and others. Interestingly, this G3TM PKD and the classical PKD1/2 deficient PKD shared common pathways, possibly because the mutant p53S could regulate the expression levels of PKD1/2, Pkhd1, and Hnf1b.Conclusions: We established a dual mouse model for PKD and tumorigenesis derived from abnormal cellular proliferation and telomere dysfunction. The innovative point of our study is to report PKD occurring in conjunction with tumorigenesis. The gene signatures revealed might shed new light on the pathogenesis of PKD, and provide new molecular biomarkers for clinical diagnosis and prognosis. 展开更多
关键词 P53 MUTATION telomere dysfunction POLYCYSTIC kidney disease tumorigenesis
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An electrodeposition approach to metal/metal oxide heterostructures for active hydrogen evolution catalysts in near-neutral electrolytes
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作者 Michael J.Kenney Jianan Erick Huang +9 位作者 Yong Zhu Yongtao Meng Mingquan Xu Guanzhou Zhu Wei-Hsuan Hung Yun Kuang Mengchang Lin Xiaoming Sun Wu Zhou Hongjie Dai 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第6期1431-1435,共5页
Neutral water splitting is attractive for its use of non-corrosive and environmentally friendly electrolytes.However,catalyst development for hydrogen and oxygen evolution remains a challenge under neutral conditions.... Neutral water splitting is attractive for its use of non-corrosive and environmentally friendly electrolytes.However,catalyst development for hydrogen and oxygen evolution remains a challenge under neutral conditions.Here we report a simple electrodeposition and reductive annealing procedure to produce a highly active Ni-Co-Cr metal/metal oxide heterostructured catalyst directly on Ni foam.The resulting electrocatalyst for hydrogen evolution reaction (HER) requires only 198 mV of overpotential to reach 100 mNcm2 in 1 M potassium phosphate (pH =7.4) and can operate for at least two days without significant performance decay.Scanning transmission electron microscopy coupled with electron energy loss spectroscopy (STEM-EELS) imaging reveals a Ni-Co alloy core decorated with blended oxides layers of NiO,CoO and Cr2O3.The metal/metal oxide interfaces are suggested to be responsible for the high HER activity. 展开更多
关键词 water SPLITTING CATALYSIS NANOSTRUCTURED materials hydrogen EVOLUTION chemical mapping
Cumulative activation in social networks
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作者 Xiaohan SHAN Wei CHEN +2 位作者 Qiang LI Xiaoming SUN Jialin ZHANG 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第5期108-128,共21页
Most studies on influence maximization focus on one-shot propagation, i.e., the influence is propagated from seed users only once following a probabilistic diffusion model and users’ activation are determined via sin... Most studies on influence maximization focus on one-shot propagation, i.e., the influence is propagated from seed users only once following a probabilistic diffusion model and users’ activation are determined via single cascade. In reality it is often the case that a user needs to be cumulatively impacted by receiving enough pieces of information propagated to her before she makes the final purchase decision. In this paper we model such cumulative activation as the following process: first multiple pieces of information are propagated independently in the social network following the classical independent cascade model, then the user will be activated(and adopt the product) if the cumulative pieces of information she received reaches her cumulative activation threshold. Two optimization problems are investigated under this framework: seed minimization with cumulative activation(SM-CA), which asks how to select a seed set with minimum size such that the number of cumulatively active nodes reaches a given requirement η;influence maximization with cumulative activation(IM-CA), which asks how to choose a seed set with fixed budget to maximize the number of cumulatively active nodes. For SM-CA problem, we design a greedy algorithm that yields a bicriteria O(ln n)-approximation when η = n, where n is the number of nodes in the network. For both SM-CA problem with η < n and IM-CA problem, we prove strong inapproximability results. Despite the hardness results, we propose two efficient heuristic algorithms for SM-CA and IM-CA respectively based on the reverse reachable set approach. Experimental results on different real-world social networks show that our algorithms significantly outperform baseline algorithms. 展开更多
关键词 social networks CUMULATIVE ACTIVATION influence MAXIMIZATION SEED MINIMIZATION
Photosynthetic traits and antioxidative defense responses of Pinus yunnanensis after joint attack by bark beetles Tomicus yunnanensis and T.minor 预览
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作者 Juan Liu Hang Chen +3 位作者 Jianmin Wang Xiaoming Chen Zixiang Yang Junsheng Liang 《林业研究:英文版》 CAS CSCD 2019年第6期2031-2038,共8页
Bark beetles Tomicus yunnanensis and T.minor are two important pests of Pinus yunnanensis and can cause massive death of pine trees.In this study,we examined several traits related to photosynthesis in P.yunnanensis a... Bark beetles Tomicus yunnanensis and T.minor are two important pests of Pinus yunnanensis and can cause massive death of pine trees.In this study,we examined several traits related to photosynthesis in P.yunnanensis and their relationship with antibiotic defense responses after joint attack by the two bark beetles at the shoot and the trunk stages.When shoots were attacked by the beetles,the abundance of chlorophylls,carotenoids,and the rates of net photosynthesis(Pn)and transpiration(E)decreased in needles,while the levels of superoxide dismutase and malondialdehyde remained unchanged in both needles and phloem.The activity of peroxidases also remained unchanged in needles,but increased in phloem.The activity of catalases increased in both needles and phloem.When trunks were attacked by the bark beetles,chlorophyll abundance,Pn,E,and antioxidative enzyme activities all declined,and the declines were more pronounced than in the attacked shoots.A decrease in protein concentrations was also observed in needles and phloem from the attacked pines.Attack on shoots by the bark beetles suppressed host defense and provided a favorable environment for larval growth and development,resulting in long-term decline of pine growth potential.The results suggest that attacks on trunks by beetles caused more severe damage to host trees than attacks on shoots. 展开更多
关键词 Antioxidant enzymes BARK BEETLE Defense responses Photosynthesis PINUS yunnanensis Tomicus MINOR Tomicus yunnanensis
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Preparation and anisotropic properties of textured structural ceramics: A review
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作者 Zhuo ZHANG Xiaoming DUAN +5 位作者 Baofu QIU Zhihua YANG Delong CAI Peigang HE Dechang JIA Yu ZHOU 《先进陶瓷(英文版)》 CSCD 2019年第3期289-332,共44页
Ceramics are usually composed of randomly oriented grains and intergranular phases, so their properties are the statistical average along each direction and show isotropy corresponding to the uniform microstructures. ... Ceramics are usually composed of randomly oriented grains and intergranular phases, so their properties are the statistical average along each direction and show isotropy corresponding to the uniform microstructures. Some methods have been developed to achieve directional grain arrangement and preferred orientation growth during ceramic preparation, and then textured ceramics with anisotropic properties are obtained. Texture microstructures give particular properties to ceramics along specific directions, which can effectively expand their application fields. In this review, typical texturing techniques suitable for ceramic materials, such as hot working, magnetic alignment, and templated grain growth(TGG), are discussed. Several typical textured structural ceramics including α-Al2O3 and related nacre bioinspired ceramics, Si3N4 and SiAlON, h-BN, MB2 matrix ultra-high temperature ceramics, MAX phases and their anisotropic properties are presented. 展开更多
关键词 TEXTURE structural CERAMICS ANISOTROPIC properties strengthening and TOUGHENING MECHANISMS
Preparation and Adsorption Properties of Biomass Activated Carbon from Ginger Stems 预览
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作者 Jinling Liu Xiaoming Song +1 位作者 Shanshan Gao Fushan Chen 《造纸与生物质材料:英文版》 2019年第4期45-50,共6页
Biomass activated carbon(BAC)was produced from ginger stems by carbonization and activation presented high specific surface areas and mesoporous structures.The carbonization temperature of the ginger stems were contro... Biomass activated carbon(BAC)was produced from ginger stems by carbonization and activation presented high specific surface areas and mesoporous structures.The carbonization temperature of the ginger stems were controlled within 500~900℃.The optimal carbonization condition is as follows:carbonization temperature of 700℃,carbonization time of 6 h.The determined optimum activation condition is:temperature of 800℃,activator of KOH and carbonized product/alkali ratio of 1:4(w/w).The carbonization yield,BAC yield and Brunauer-Emmett-Teller(BET)surface area were measured and the adsorption performance of BAC to nitrogen was investigated.The results showed that the nitrogen adsorption isotherm curve was as type I isotherm.It was finally determined that the BET surface area was 660 m2/g under the abovementioned optimal conditions of carbonization and activation.The FESEM analysis indicates that the obtained BAC is of micropore structure. 展开更多
关键词 ginger stems biomass activated carbon CARBONIZATION activation
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Seabed deposition and erosion change and influence factors in the Yangshan Deepwater Port over the years 预览
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作者 Shuhua Zuo Hualiang Xie +4 位作者 Xiaoming Ying Cheng Cui Yuxin Huang Huaiyuan Li Mingxiao Xie 《海洋学报:英文版》 SCIE CAS CSCD 2019年第7期96-106,共11页
The seabed scouring and silting are very important to the construction of port and waterway engineering.Seabed deposition and erosion change is complicated due to the influence of sediment supply,human activities and ... The seabed scouring and silting are very important to the construction of port and waterway engineering.Seabed deposition and erosion change is complicated due to the influence of sediment supply,human activities and other factors.The Yangshan Deepwater Port is the new deep water harbor,which is an important part of the Shanghai International Shipping Service Center.Its construction has received much attention.At present,the water depth from the 1st to the 3rd harbor district is currently suitable under regular dredging and tidal current action.The fourth harbor district will be built in the world’s largest fully-automated deep water wharf.In the study,bathymetry change of the entire sea area of the Yangshan Deepwater Port and the 4th harbor district(i.e.,PhaseⅣproject)waters were analyzed quantitatively using multiyear bathymetric,hydrological and sediment data.The results show that from 1998 to 2010,seabed changes are characterized by large volumes of erosion and sedimentation,which the southern part was deposited and the northern part was eroded in the inner harbor waters,but the seabed of the Kezhushan inlet was eroded.Seabed changes of PhaseⅣproject waters generally show a scour tendency in recent few years with the annual scour rate about 0.7 m.Among the many factors,the existence of Kezhushan inlet and its influence of the western water flow play an important positive role in water depth changes under the ebb tide action. 展开更多
关键词 Yangshan DEEPWATER Port phaseⅣproject water and sediment environment SEABED DEPOSITION and EROSION CHANGE diversion DIKE
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