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Dynamic Variability in Daily Temperature Extremes and Their Relationships with Large-scale Atmospheric Circulation During 1960–2015 in Xinjiang, China

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Chinese Geographical Science 2020年第2期30卷 233-248页

作者： zhang kexin DAI Shengpei DONG Xiaogang School of Management Science Guizhou University of Finance and EconomicsGuiyang 550025China Yangzhou Hongshuo Environmental and Biological Engineering Research Co.Ltd. Yangzhou 225157China Institute of Scientific and Technical Information Chinese Academy of Tropical Agricultural SciencesHaikou 571101China College of Geography and Environmental Science Northwest Normal UniversityLanzhou 730070China

Climate changes are likely to increase the risk of numerous extreme weather events throughout the *** objectives of this study were to investigate and analyze the temporal-spatial variability patterns of temperature extremes based on daily maximum(TX)and minimum temperature(TN)data collected from 49 meteorological stations in Xinjiang of China during 1960–*** temperature data were also used to assess the impacts of altitude on the temperature ***,possible teleconnections with the large-scale circulation pattern(the El Nino-Southern Oscillation,ENSO and Arctic Oscillation,AO)were *** showed that all percentile indices had trends consistent with warming in most parts of Xinjiang during 1960–2015,but the warming was more pronounced for indices derived from TN compared to those from *** minimum TN and maximum TX increased at rates of 0.16℃/10 yr and 0.59℃/10 yr,respectively during 1960–***,the diurnal temperature range showed a significant decreasing trend of–0.23℃/10 yr for the whole study *** frequency of the annual average of the warm events showed significant increasing trends while that of the cold events presented decreasing *** the same period,the number of frost days showed a statistically significant decreasing trend of–3.37 d/10 *** number of the summer days and the growing season showed significant increasing trends at rates of 1.96 and 2.74 d/10 yr,*** abrupt change year of each index was from the 1980 s to the 1990 s,showing that this periodic interval was a transitional phase between cold and warm climate *** correlations of temperature extremes and elevation included the trends of tropical nights,growing season frequency,and cold spell duration *** result also indicated the clear and complex local influence on climatic *** addition,the relationship between each index of the temperature extremes with large-scale atmospheric circula

关键词： climate variability temperature extremes altitude atmospheric circulation Xinjiang,China

The Mid-Miocene Pollen Record of the Xunhua Basin, NE Tibetan Plateau: Implications for Global Climate Change

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Acta Geologica Sinica(English Edition) 2015年第5期89卷 1649-1663页

作者： XU Zenglian zhang Jianyu JI Junliang zhang kexin School of Earth Sciences China University of GeoscienceWuhan State Key Laboratory of Biogeology and Envicronmental Geology China University of GeoscienceWuhan China Geological Survey Wuhan Center

The northeastern Tibetan Plateau is located at the convergence of the Asian winter and summer monsoons and westerlies; thus, this area has witnessed historic climate *** Xunhua basin is an intermontane basin on the northeastern margin of the Tibetan *** basin contains more than 2000 m of Cenozoic fluvial–lacustrine sediments, recording a long history of climate and environmental *** collected the mid-Miocene sediments from the Xunhua basin and used palynological methods to discuss the relationship between aridification in the interior of Asia, global cooling, and uplift of the Tibetan *** on the palynological analysis of the Xigou section, Xunhua basin, the palynological diagram is subdivided into three pollen zones and past vegetation and climate are *** I, Ephedripites–Nitraridites–Chenopodipollis–Quercoidites（14.0–12.5 Ma）, represents mixed shrub–steppe vegetation with a dry and cold *** zone II, Pinaceae–Betulaepollenites–Ephedripites–Chenopodipollis–Graminidites（12.5–8.0 Ma）, the vegetation and climate conditions improved, even though the vegetation was still dominated by shrub–steppe *** III, Ephedripites–Nitrariadites–Chenopodipollis（8.0–5.0 Ma）, represents desert steppe vegetation with drier and colder *** palynological records suggest that shrub–steppe dominated the whole Xigou section and the content gradually increased, implying a protracted aridification process, although there was an obvious climate improvement during 12.5–8.0 *** aridification in the Xunhua basin and surrounding mountains during 14.0–12.5 Ma was probably related to global cooling induced by the rapid expansion of the East Antarctic ice-sheets and the relatively higher evaporation *** the 12.5–8.0 Ma period, although topographic changes（uplift of Jishi Shan） decreased precipitation and strengthened aridification in the Xunhua basin on leeward slopes, the improved vegetation and climate conditions were probab

关键词： pollen mid-miocene aridification Xunhua basin northeastern Tibetan Plateau

Metal-organic framework based nanomaterials for electrocatalytic oxygen redox reaction

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Science China Chemistry 2019年第4期62卷 417-429页

作者： kexin zhang Wenhan Guo Zibin Liang Ruqiang Zou Beijing Key Laboratory for Theory and Technology of Advanced Battery Materials Department of Materials Science and EngineeringCollege of Engineering Peking University

Due to the severe environmental issues, many advanced technologies, typically fuel cells and metal-air batteries have aroused widespread concerns and been intensively studied in recent years. However, oxygen redox reactions including oxygen evolution reaction(OER) and oxygen reduction reaction(ORR) as the core reactions suffer from sluggish kinetics of the multiple electron transfer process. Currently, Pt, RuO_2, and IrO_2 are considered to be the benchmark catalysts for ORR and OER, but their high price, scarcity and instability hinder them from large-scale application. To overcome these limits, exploring alternative electrocatalysts with low cost, high activity, long-term stability, and earth-abundance is of extreme urgency. Metal-organic frameworks(MOFs) are a family of inorganic-organic hybrid materials with high surface areas and tunable structures, making them proper as catalyst candidates. Herein, the recent progress of MOFs and MOF-derived materials for ORR and OER is systematically reviewed, and the relationship between compositions and electrochemical performance is discussed. It is expected that this review can be helpful for the future development of related MOF-based materials with excellent electrochemical performance.

关键词： metal-organic frameworks oxygen evolution reaction oxygen reduction reaction earth-abundant materials electrocatalysis nanomaterials

Unequal error protection scheme for layered sources transmission over MIMO systems using spatial diversity and multiplexing technology

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The Journal of China Universities of Posts and Telecommunications 2015年第3期22卷 56-63页

作者： zhang Yongjian zhang kexin Kang Yanmei Yang Dacheng School of Telecommunication Engineering Beijing University of Posts and Telecommunications University of International Relations Academic office Beijing University of Posts and Telecommunications

This paper proposes a hybrid scheme of the Alamouti coding and vertical bell labs layered space-time （V-BLAST） with the zero-forcing （ZF） receiver, which can achieve the unequal error protection （UEP） transmission in terms of the differences of importance in the layered sources. We analyze the tradeoff between spatial diversity and multiplexing in a mathematical manner, and prove the monotonic behavior of the crosspoint. Based on this scheme, we adopt V-BLAST to provide high data rates for the enhancement layer （EL） bitstreams, and adopt Alamouti coding to guarantee high reliability for the base layer （BL） bitstreams. Meanwhile, to improve the transmission reliability for the layered sources under the multiple-input multiple-output （MIMO） system with the limited-bandwidth and the total limited power, and to raise the frequency bandwidth efficiency, we take the power allocation considered in this proposed scheme. The simulation results show that the hybrid scheme has the average 1.9 dB and 1.3 dB gain in video peak signal-to-noise ratio （PSNR）, compared with the pure spatial diversity and pure spatial multiplexing scheme, respectively.

关键词： unequal error protection spatial diversity and multiplexing outage probability multiple-input multiple-output (MIMO) powerallocation

Acetylated-PPARγexpression is regulated by different P53 genotypes associated with the adipogenic differentiation of polyploid giant cancer cells with daughter cells

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Cancer Biology & Medicine 2023年第1期20卷 56-76页

作者： kexin zhang Xiaohui Yang Minying Zheng Yidi Ning Shiwu zhang Tianjin Union Medical Center Tianjin 300122China Nankai University School of Medicine Nankai UniversityTianjin 300071China

Objective:Polyploid giant cancer cells(PGCCs)with daughter cells express epithelial–mesenchymal transition(EMT)-associated *** malignant tumor cells with EMT properties can transdifferentiate into mature tumor *** this study,we elucidated the potential for,and underlying mechanism of,adipogenic differentiation of PGCCs with daughter cells(PDCs).Methods:Cobalt chloride was used to induce PGCC formation in HEY(wild-type P53)and MDA-MB-231(mutant P53)cells;these cells were then cultured in adipogenic differentiation *** red O staining was used to confirm adipogenic differentiation,and the cell cycle was detected with flow *** expression of adipogenic differentiation-associated proteins and P300 histone acetyltransferase activity were compared before and after adipogenic *** xenograft models were used to confirm the adipogenic differentiation of ***:PDCs transdifferentiated into functional *** different cell cycle distributions were observed in PDCs after adipogenic *** expression levels of PPARγ,Ace-PPARγ,and Ace-P53 were higher in PDCs after adipogenic differentiation than in cells before adipogenic ***-PPARγand FABP4 expression increased in HEY cells and decreased in MDA-MB-231 PDCs after p53 knockdown.A485 treatment increased Ace-P53,Ace-PPARγ,and FABP4 expression in HEY PDCs by inhibiting SUMOylation of *** MDA-MB-231 PDCs,A485 treatment decreased Ace-P53,Ace-PPARγ,and FABP4 *** experiments also confirmed the adipogenic differentiation of ***:Acetylation of P53 and PPARγplays an important role in the adipogenic differentiation of PDCs.

关键词： PGCCs adipogenic differentiation PPARγ post-translational modification P53 genotype

Exergy Analysis of Electric Vehicle Heat Pump Air Conditioning System with Battery Thermal Management System

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Journal of Thermal Science 2020年第2期29卷 408-422页

作者： zhang kexin LI Ming YANG Changhai SHAO Zhiyuan WANG Lihong State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130025China College of Automotive Engineering Jilin UniversityChangchun 130025China School of Energy and Power Engineering Xi’an Jiaotong UniversityXi’an 710049China FAW-Valeo Climate Control Systems Co.Ltd. Changchun 130011China

The exergy analysis of an electric vehicle heat pump air conditioning system(HPACS) with battery thermal management system was carried out by studying the exergy loss of each component. The results indicate that the compressor is the main source of system exergy loss in all operation conditions. The exergy loss distribution of HPACS is almost the same when the battery thermal management system integrated into the HPACS in cabin and battery mixed cooling mode and the system exergy loss was linearly related to the compressor speed in cooling modes. The performance of the HPACS is better than that of the positive temperature coefficient(PTC) heater in cabin heating mode. The degree of exergy efficiency improvement of the alternative mode was discussed at all operation conditions in cabin heating mode. The results indicate that the optimization effect using the electric vehicle HPACS to replace the PTC heater is obvious at lower compressor speed, surrounding temperature and internal condenser air flow rate.

关键词： electric vehicle heat pump exergy efficiency battery thermal management

A Review on the Global Stratotype Section and Point of the Permian-Triassic Boundary

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Acta Geologica Sinica(English Edition) 2005年第6期79卷 715-728页

作者： YIN Hongfu TONG Jinnan zhang kexin Lab of Biological and Environmental Geology China University of Geosciences Wuhan Hubei 430074 State Key Lab of Geological Process and Mineral Resources China University of Geosciences Wuhan Hubei 430074

This paper provides a synthetic review of researches on Meishan Section D, the Global Stratotype Section and Point of the Permian-Triassic Boundary （PTB）. The history of research, geographic and geological setting of the section are briefly introduced. Changhsingian to ＂Griesbachian＂ conodont and ammonoid zonations, the most perfect Permo-Triassic zonations over the world, are presented, with a short discussion on the age of Otoceras, The Changhsingian to ＂Griesbachian＂ strata are subdivided into three 3rd order sequences, and the sedimentary structure of each sequence is indicated. The paper presents a correlation of the Changhsingian to ＂Griesbachian＂ magneetostratigraphy of the Meishan section with the general scale, and informed the negation of a short magnetic reversal at the PTB suggested by Zhu and Liu （1999）. Recent developments of chemostratigraphy of δ^13C and δ^34S are introduced, especially the discovery of more than one negative δ^13C excursions across the PTB. Two important molecular researches reveal the profound changes at the base of eco-system, the microbial catastrophy, and the euxinic conditions in the photic zone during the Permian-Triassic superanoxic event. The paper reports the changes in dating the age of PTB since 2001. According to recent achievements, the age of volcanogenic claybed 25, 14 cm below the PTB, is now set at 252.4±0.3 Ma. A discussion on the eventostratigraphy concludes that, although there is a major event episode at beds 25-26, the events across the PTB at Meishan are multi-episodic and commenced prior to the Event Beds 25-26, thus the possibility that the mass extinction was mainly induced by an exterrestrial impact is largely excluded.

关键词： review Global Stratotype Section and Point Permian-Triassic Boundary Meishan China

Porous nanofibrous dressing enables mesenchymal stem cell spheroid formation and delivery to promote diabetic wound healing

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Chinese Journal of Chemical Engineering 2024年第4期68卷 156-164页

作者： kexin zhang Wenmin zhang Heng An Zhe Huang Yanzhen Wen Xiangyu Jiao Yongqiang Wen College of Chemical Engineering and Technology Taiyuan University of Science and TechnologyTaiyuan 030024China Beijing Key Laboratory for Bioengineering and Sensing Technology Daxing Research InstituteSchool of Chemistry&Biological EngineeringUniversity of Science&Technology BeijingBeijing 100083China

Delayed and nonhealing of diabetic wounds imposes substantial economic burdens and physical pain on *** stem cells(MSCs)promote diabetic wound *** when MSCs aggregate into multicellular spheroids,their therapeutic effect is ***,traditional culture platforms are inadequate for the efficient preparation and delivery of MSC spheroids,resulting in inefficiencies and inconveniences in MSC spheroid *** this study,a three-dimensional porous nanofibrous dressing(NFD)is prepared using a combination of electrospinning and homogeneous *** thermal crosslinking,the NFD not only achieves satisfactory elasticity but also maintains notable *** the design of its structure and chemical composition,the NFD allows MSCs to spontaneously form MSC spheroids with controllable sizes,serving as MSC spheroid delivery systems for diabetic wound *** importantly,MSC spheroids cultured on the NFD exhibit improved secretion of vascular endothelial growth factor,basic fibroblast growth factor,and hepatocyte growth factor,thereby accelerating diabetic wound *** NFD provides a competitive strategy for MSC spheroid formation and delivery to promote diabetic wound healing.

关键词： Electrospinning Homogenization Biomedical engineering Nanomaterials Stem cell spheroids Diabetic wound healing

Size variation of the end Permian conodont Neogondolella at Meishan Section,Changxing,Zhejiang and its significance

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Science China Earth Sciences 2006年第4期49卷 337-347页

作者： LUO Genming LAI Xulong JIANG Haishui zhang kexin Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China

This study is based on both a generic and species level investigation of the individual size of the latest Permian conodont Neogondolella Pa elements collected from Meishan Section A, Changxing, Zhejiang Province. In this study, an obvious size reduction of Neogondolella Pa elements within bed 24e of the upper Changxing Limestone is recognized. The size variation of the Neogon- dolella occurs simultaneously with some important events including the negative shift of δ 13C, change in the ratio of the abundance of cyanobacterial biomarkers versus that of other general bacterial biomarkers and the shallowing of the sea water. Through the investigation of the paleoenvironmental changes and the analysis of the paleoecology of the conodont genus Neogondolella, the authors propose that the major factors for the size reduction of species of the conodont genus Neogondolella are food shortages caused by the mass extinction, the shallowing of the sea water as well as the in- crease in opacity of the sea water during the end Permian. The same phenomenon of Neogondolella size reduction is also observed in preliminary research from the same horizon at Shangsi Section, Sichuan Province. All the evidence suggests that there was a mass extinction that occurred at the horizon of bed 24e, and the evidence supports the viewpoint of a multi-phase mass extinction during the Permian and Triassic transition in South China.

关键词： Meishan Section, end Permian, conodont, Neogondolella, size reduction.