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Near-surface wind field characteristics of the desert-oasis transition zone in Dunhuang,China

Journal of Arid Land 2024年第5期16卷 654-667页

作者： PAN Jiapeng zhang Kecun AN Zhishan zhang yu Key Laboratory of Desert and Desertification&Dunhuang Gobi and Desert Ecology and Environment Research Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China

The desert-oasis transition zone(DOTZ)serves as a buffer area between the desert and *** its wind field characteristics is of great significance for the prevention and control of aeolian disasters in the *** this study,we used meteorological data during 2013–2019 from the portable meteorological stations at five sites(site A on the edge of the oasis,sites B,C,and D in the DOTZ,and site O in the desert)in Dunhuang,China to analyze the near-surface wind field characteristics and their causes,as well as to reveal the key role of the DOTZ in oasis *** results showed that the mean wind speed,frequency of sand-driving wind,and directional variability of wind decreased from west to east within the DOTZ,and wind speed was significantly affected by air *** terrain influenced the prevailing winds in the region,mainly from northeast and *** some areas adjacent to the oasis were controlled by southeasterly *** indicated that the near-surface wind field characteristics of the DOTZ were caused by the combined effects of local terrain and surface hydrothermal *** site D,the annual drift potential(DP)was 24.95 vector units(VU),indicating a low wind energy environment,and the resultant drift direction(RDD)showed obvious seasonal ***,the DOTZ played an important buffering role between the desert and *** with the desert,the mean wind speed in the oasis decreased by 64.98%,and the prevailing wind direction was more *** results of this study will be useful in interpreting the aeolian activity of the DOTZ in Dunhuang.

关键词： desert-oasis transition zone near-surface wind field hydrothermal difference sand-driving wind aeolian environment Dunhuang

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In situ embedded bismuth nanoparticles among highly porous carbon fibers for efficient carbon dioxide reduction

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Rare Metals 2024年第9期43卷 4312-4320页

作者： Wei-Jian Guo Ao Zhou Wen-Wen cai Jin-Tao zhang Key Laboratory for Colloid and Interface Chemistry(Ministry of Education) School of Chemistry and Chemical EngineeringShandong UniversityJinan 250100China

Electrocatalysis provides an optimal approach for the conversion of carbon dioxide(CO_(2))into high-value chemicals,thereby presenting a promising avenue toward achieve carbon ***,addressing the selectivity and stability challenges of metal catalysts in electrolytic reduction remains a daunting *** this study,the electrospinning method is employed to fabricate porous carbon nanofibers loaded with bismuth nanoparticles with the help of in situ *** porous carbon nanofibers as conductive support would facilitate the dispersion of bismuth active sites while inhibiting their aggregation and promoting the mass transfer,thus enhancing their electrocatalytic activity and ***,nitrogen doping induces electron delocalization in bismuth atoms through metal-support interactions,thus enabling efficient adsorption of intermediates for improving selectivity based on the theoretical ***,Bi@PCNF-500 exhibits the exceptional selectivity and stability across a wide range of potential ***,its faradaic efficiency(FE)of formate reaches 92.7%in H-cell and94.9%in flow cell,respectively,with good electrocatalytic *** in situ characterization and theoretical calculations elucidate the plausible reaction mechanism to obtain basic rules for designing efficient electrocatalyst.

关键词： Porous carbon nanofiber N-doping Electron delocalization Carbon dioxide reduction

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Complete kinetic model for esterification reaction of lauric acid with glycerol to synthesize glycerol monolaurate

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Chinese Journal of Chemical Engineering 2024年第6期70卷 211-221页

作者： Han-Qiao Hu yue zhang Ming Fan Yong cai Guang-Wen Chu Liang-Liang zhang Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Petrochemical Research Institute China National Petroleum CorporationBeijing 102206China

Glycerol monolaurate(GML)is a widely used industrial chemical with excellent emulsification and antibacterial *** direct esterification of glycerol with lauric acid is the main method to synthesize *** this work,the kinetic process of direct esterification was systematically studied using p-toluenesulfonic acid as catalyst.A complete kinetic model of consecutive esterification reaction has been established,and the kinetic equation of acid catalysis was *** isomerization reactions of GML and glycerol dilaurate were *** was found that the reaction was an equilibrium reaction and the reaction rate was faster than the esterification *** kinetic equations of the consecutive esterification reaction were obtained by experiments as k_(1)=(276+92261Xcat)exp(-37720/RT)and k_(2)=(80+4413Xcat)exp(-32240/RT).The kinetic results are beneficial to the optimization of operating conditions and reactor design in GML production process.

关键词： Glycerol monolaurate p-Toluenesulfonic acid Esterification Kinetics Mass transfer

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Ti_(3)C_(2)T_(x) MXene/carbon composites for advanced supercapacitors:Synthesis,progress,and perspectives

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Carbon Energy 2024年第2期6卷 113-142页

作者： Yanqing cai Xinggang Chen Ying Xu Yalin zhang Huijun Liu Hongjuan zhang Jing Tang College of Materials Science and Engineering North China University of Science and TechnologyTangshanChina Hebei Iron and Steel Laboratory North China University of Science and TechnologyTangshanChina Songshan Lake Materials Laboratory DongguanChina Shanghai Key Laboratory of Green Chemistry and Chemical Processes School of Chemistry and Molecular EngineeringEast China Normal UniversityShanghaiChina State Key Laboratory of Petroleum Molecular and Process Engineering(SKLPMPE) Sinopec Research Institute of Petroleum Processing Co.Ltd.BeijingChina Institute of Eco-Chongming ShanghaiChina

MXenes are a family of two-dimensional(2D)layered transition metal carbides/nitrides that show promising potential for energy storage applications due to their high-specific surface areas,excellent electron conductivity,good hydrophilicity,and tunable *** various types of MXenes,Ti_(3)C_(2)T_(x) is the most widely studied for use in capacitive energy storage applications,especially in supercapacitors(SCs).However,the stacking and oxidation of MXene sheets inevitably lead to a significant loss of electrochemically active *** overcome such challenges,carbon materials are frequently incorporated into MXenes to enhance their electrochemical *** review introduces the common strategies used for synthesizing Ti_(3)C_(2)T_(x),followed by a comprehensive overview of recent developments in Ti_(3)C_(2)T_(x)/carbon composites as electrode materials for ***_(3)C_(2)T_(x)/carbon composites are categorized based on the dimensions of carbons,including 0D carbon dots,1D carbon nanotubes and fibers,2D graphene,and 3D carbon materials(activated carbon,polymer-derived carbon,etc.).Finally,this review also provides a perspective on developing novel MXenes/carbon composites as electrodes for application in SCs.

关键词： electrochemical performance MXene/carbon composites supercapacitors

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Spatiotemporal variation of land surface temperature and its driving factors in Xinjiang,China

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Journal of Arid Land 2024年第3期16卷 373-395页

作者： zhang Mingyu CAO yu zhang Zhengyong zhang Xueying LIU Lin CHEN Hongjin GAO yu yu Fengchen LIU Xinyi College of Sciences Shihezi UniversityShihezi 832000China Key Laboratory of Oasis Town and Mountain-Basin System Ecology Xinjiang Production and Construction CorpsShihezi 832000China Yantai Institute of Coastal Zone Research Chinese Academy of SciencesYantai 264003China

Land surface temperature(LST) directly affects the energy balance of terrestrial surface systems and impacts regional resources, ecosystem evolution, and ecosystem structures. Xinjiang Uygur Autonomous Region is located at the arid Northwest China and is extremely sensitive to climate change. There is an urgent need to understand the distribution patterns of LST in this area and quantitatively measure the nature and intensity of the impacts of the major driving factors from a spatial perspective, as well as elucidate the formation mechanisms. In this study, we used the MOD11C3 LST product developed on the basis of Moderate Resolution Imaging Spectroradiometer(MODIS) to conduct regression analysis and determine the spatiotemporal variation and differentiation pattern of LST in Xinjiang from 2000 to 2020. We analyzed the driving mechanisms of spatial heterogeneity of LST in Xinjiang and the six geomorphic zones(the Altay Mountains, Junggar Basin, Tianshan Mountains, Tarim Basin, Turpan-Hami(Tuha) Basin, and Pakakuna Mountain Group) using geographical detector(Geodetector) and geographically weighted regression(GWR) models. The warming rate of LST in Xinjiang during the study period was 0.24℃/10a, and the spatial distribution pattern of LST had obvious topographic imprints, with 87.20% of the warming zone located in the Gobi desert and areas with frequent human activities, and the cooling zone mainly located in the mountainous areas. The seasonal LST in Xinjiang was at a cooling rate of 0.09℃/10a in autumn, and showed a warming trend in other seasons. Digital elevation model(DEM), latitude, wind speed, precipitation, normalized difference vegetation index(NDVI), and sunshine duration in the single-factor and interactive detections were the key factors driving the LST changes. The direction and intensity of each major driving factor on the spatial variations of LST in the study area were heterogeneous. The negative feedback effect of DEM on the spatial differentiation o

关键词： land surface temperature MOD11C3 climate change geographical detector(Geodetector) geographically weighted regression(GWR) source-sink effect Xinjiang

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A probabilistic generative model for tracking multi-knowledge concept mastery probability

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Frontiers of Computer Science 2024年第3期18卷 155-170页

作者： Hengyu LIU Tiancheng zhang Fan LI Minghe yu Ge yu School of Computer Science and Engineering Northeastern UniversityShenyang 110169China Software College Northeastern UniversityShenyang 110169China

Knowledge tracing aims to track students’knowledge status over time to predict students’future performance *** a real environment,teachers expect knowledge tracing models to provide the interpretable result of knowledge *** chain-based knowledge tracing(MCKT)models,such as Bayesian Knowledge Tracing,can track knowledge concept mastery probability over ***,as the number of tracked knowledge concepts increases,the time complexity of MCKT predicting student performance increases exponentially(also called explaining away problem).When the number of tracked knowledge concepts is large,we cannot utilize MCKT to track knowledge concept mastery probability over *** addition,the existing MCKT models only consider the relationship between students’knowledge status and problems when modeling students’responses but ignore the relationship between knowledge concepts in the same *** address these challenges,we propose an inTerpretable pRobAbilistiC gEnerative moDel(TRACED),which can track students’numerous knowledge concepts mastery probabilities over *** solve explain away problem,we design long and short-term memory(LSTM)-based networks to approximate the posterior distribution,predict students’future performance,and propose a heuristic algorithm to train LSTMs and probabilistic graphical model *** better model students’exercise responses,we proposed a logarithmic linear model with three interactive strategies,which models students’exercise responses by considering the relationship among students’knowledge status,knowledge concept,and *** conduct experiments with four real-world datasets in three knowledge-driven *** experimental results show that TRACED outperforms existing knowledge tracing methods in predicting students’future performance and can learn the relationship among students,knowledge concepts,and problems from students’exercise *** also conduct several case *** case studies show that

关键词： probabilistic graphical model deep learning knowledge tracing learner modeling

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Ignition processes and characteristics of charring conductive polymers with a cavity geometry in precombustion chamber for applications in micro/nano satellite hybrid rocket motors

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Defence Technology（防务技术） 2024年第2期32卷 55-66页

作者： Zhiyuan zhang Hanyu Deng Wenhe Liao Bin yu Zai yu Nanjing University of Science and Technology Nanjing 210094China

The arc ignition system based on charring polymers has advantages of simple structure,low ignition power consumption and multiple ignitions,which bringing it broadly application prospect in hybrid propulsion system of micro/nano ***,charring polymers alone need a relatively high input voltage to achieve pyrolysis and ignition,which increases the burden and cost of the power system of micro/nano satellite in practical *** conductive substance into charring polymers can effectively decrease the conducting voltage which can realize low voltage and low power consumption repeated ignition of arc ignition *** this paper,a charring conductive polymer ignition grain with a cavity geometry in precombustion chamber,which is composed of PLA and multiwall carbon nanotubes(MWCNT)was *** detailed ignition processes were analyzed and two different ignition mechanisms in the cavity of charring conductive polymers were *** ignition characteristics of charring conductive polymers were also investigated at different input voltages,ignition grain structures,ignition locations and injection schemes in a visual ignition *** results demonstrated that the ignition delay and external energy required for ignition were inversely correlated with the voltages applied to ignition ***,the incremental depth of cavity shortened the ignition delay and external energy required for ignition while accelerated the propagation of *** the depth of cavity increased from 2 to 6 mm(at 50 V),the time of flame propagating out of ignition grain changed from 235.6 to 108 ms,and values of mean ignition delay time and mean external energy required for ignition decreased from 462.8 to 320 ms and 16.2 to 10.75 J,*** rear side of the cavity was the ideal ignition position which had a shorter ignition delay and a faster flame propagation speed in comparison to other ignition *** to direct injection scheme,swirlin

关键词： Micro/nano satellite hybrid propulsion Arc ignition Charring conductive polymer Ignition mechanism Ignition characteristic Repeated ignition

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Heat Transfer Characteristics of a Microchannel Heat Sink with Highly-Dense Micro-Jet Arrays

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Journal of Thermal Science 2024年第3期33卷 1148-1160页

作者： zhang yu CHEN Xiaoyan MIAO Lin CHEN Liang HOU yu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China Beijing Aerospace Technology Institute Beijing100083China

This paper proposed a new structure of highly-dense micro-jet arrays for hybrid jet-impingement/microchannel heat sinks(~120 jet per cm^(2) with jet width of 0.35 mm).Parametric study is performed to investigate the influence of structure and flow parameters on the convective heat transfer of water jet cooling in confined *** simulation results show that the optimal jet width,jet spacing and impingement distance are around 0.2 mm,0.2 mm and 0.3 mm,respectively,which can achieve a low thermal resistance as well as a relatively low pressure *** analysis of the heat transfer pathways shows that the micro-fin jet structures can extend the impinging heat transfer area and conduct a considerable proportion of heat,which can reach up to 38.9%with the Reynolds number ranging from 797.1 to *** heat transfer characteristics in the heat sink will shift from impingement dominated heat transfer to the channel-convection dominated heat transfer as the jet impingement distance increases.A correlation is proposed to predict the average Nusselt number on the stagnation area for the heat sink with different structure parameters,and the deviations of predictions from the numerical results are less than 10%.

关键词： hybrid heat sink impingement microchannel thermal management high heat flux

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Most Tibetan weedy barleys originated via recombination between Btr1 and Btr2 in domesticated barley

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Plant Communications 2024年第5期5卷 163-175页

作者： Guangqi Gao Luxi Yan yu cai yu Guo Congcong Jiang Qiang He Sarah Tasnim Zongyun Feng Jun Liu Jing zhang Takao Komatsuda Martin Mascher Ping Yang State Key Laboratory of Crop Gene Resources and Breeding/Key Laboratory of Grain Crop Genetic Resources Evaluation and Utilization(MARA)/Institute of Crop Sciences Chinese Academy of Agricultural SciencesBeijing 100081China College of Agronomy Sichuan Agricultural UniversityChengdu 611130China Leibniz Institute of Plant Genetics and Crop Plant Research 06466 SeelandGermany Crop Research Institute Shandong Academy of Agricultural SciencesJinan 250100China

Tibetan weedy barleys reside at the edges of qingke(hulless barley)fields in Tibet(Xizang).The spikes of these weedy barleys contain or lack a brittle rachis,with either two-or six-rowed spikes and either hulled or hulless grains at *** the brittle rachis trait of Tibetan weedy barleys is similar to that of wild barley(Hordeum vulgare *** Thell.),these plants share genetic similarity with domesticated *** origin of Tibetan weedy barleys continues to be ***,we show that most Tibetan weedy barleys originated from cross-pollinated hybridization of domesticated barleys,followed by hybrid self-pollination and recombination between Non-brittle rachis 1(btr1)and 2(btr2).We discovered the specific genetic ancestry of these weedy barleys in South Asian *** weedy barleys exhibit lower genetic diversity than wild and Chinese landraces/cultivars and share a close relationship with qingke,genetically differing from typical eastern and western barley *** classified Tibetan weedy barleys into two groups,brittle rachis(BR)and non-brittle rachis(NBR);these traits align with the haplotypes of the btr1 and btr2 *** wild barleys carry haplotype combinations of Btr1 and Btr2,each showing lower proportions in a population,the recombinant haplotype BTR2H8+BTR1H24 is predominant in the BR *** block analysis based on whole-genome sequencing revealed two recombination breakpoints,which are present in 80.6%and 16.8%of BR acces-sions according to marker-assisted *** events between wild and domesticated barley were rarely *** support the notion that Tibetan weedy barleys originated via recom-bination between Btr1 and Btr2 in domesticated barley.

关键词： Tibetan weedy barley agriocrithon de-domestication out-pollination recombination brittle rachis

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Glucocorticoid receptor expression on acute lung injury induced by endotoxin in rats

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World Journal of Emergency Medicine 2010年第1期1卷 65-69页

作者： yu-cai zhang Wen-qiong Zuo Qun-fang Rong Guo-liang Tong yu-ming zhang Pediatric Institute for Critical Illness Research Critical Care Center of Children's Hospital Affiliated to Shanghai JiaotongUniversity Shanghai 200040 China

In cases of severe sepsis and septic shock, a series of pathophysiological changes lead to multiple organ dysfunction *** study aimed to investigate the expression of glucocorticoid receptor mRNA in the rat lung following endotoxin （LPS） induced shock. Totally 56 SD rats were randomly divided into 4 groups： LPS shock group （n=16）, LPS＋vasoactive intestinal peptide group（VIP） group, （n=16）, LPS＋VIP＋ glucocorticoid （GC） group, （n=16）,and control group （n=8）. LPS shock was induced by intravenous injection of LPS （10 mg/kg） in rats. Within 15 minutes after LPS injection, rats in the treatment groups received VIP （5 nmol/kg） or VIP and methylprednisolone （3 mg/kg）. The control group was given normal saline instead of LPS. The rats of the four groups were sacrificed at 6 hours,24 hours after injection respectively, and the lung tissues were collected. Pathological changes of the lungs were examined by light microscopy and electron microscopy. GRmRNA expression in the lung tissues was evaluated by RT-PCR. In the LPS shock group, lung histopathology demonstrated destruction of the alveolar space,widening of the inter-alveolar space, inflammatory cell infiltration and interstitial edema. However,pathological changes in the LPS＋ VIP group and LPS＋ VIP＋GC group were milder than those in the LPS shock group. Six hours after LPS injection, GR mRNA expression was down-regulated in the LPS group （0.72± 0.24） and LPS＋ VIP group （0.88±0.27）（P〈0.05） as compared with the control group （1.17±0.22）. The LPS shock group showed a more significant down-regualtion than the LPS＋VIP group, but the difference was not statistically significant （P〉0.05）. In contrast, GRmRNA expression in the LPS＋ VIP＋GC group was significantly up-regulated at 6 hours and further at 24 hours （1.45±0.32 and 1.91±0.46 respectively）（P〈0.05）. GrmRNA expression decreased in LPS induced lung injury in rats. Combined treatment with VIP and GC mitigated lung injury ang inflammation. The mechanism may be re

关键词： Glucocorticoid GRmRNA Vasoactive intestinal peptide LPS Shock Inflammation Lung injury Rat

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