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Study on in-situ Mg_2Si/Al-Si composites with different compositions

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China Foundry 2009年第2期6卷 133-136页

作者： Jing Qingxiu zhang caixia Huang Xiaodong Institute of Material and Chemistry Engineering Jiangxi University of Science and Technology Ganzhou 341000 China

Effects of chemical composition and heat treatment on microstructures and mechanical properties of in-situ Mg2Si/Al-Si composites were investigated. It was found that, in the microstructure of an Al-5.7wt% Mg2Si composite with 8.2wt% extra Si, the binary eutectic Mg2Si locates at the grain boundaries with an undeveloped Chinese script-like morphology, and the primary reAl is formed into a cell structure due to the selective modification effect of the modifiers of mischmetal and Strontium salt; whereas in the composite with a near Al-Mg2Si eutectic composition and little extra Si content, the intercrescence eutectic Mg2Si formed with the binary eutectic a-Al grows into integrated Chinese script- like shape. As Si content increases, the eutectic Mg2Si dendrite becomes coarser in morphology but less in volume fraction. Hardness and tensile strength of the cast Mg2Si/Al-Si composites do not increase with increasing of Mg content, but they are related to the size and morphology of the eutectic and primary Mg2Si phases. Heat treatment with optimal parameters is an effective way to improve the properties of the in-situ composites.

关键词： microstructure composite Al-Mg-Si alloy heat treatment

Study on the microcosmic superlubricity mechanism of PVPA affected by metal cations

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Friction 2023年第7期11卷 1150-1164页

作者： Hongyun CAI caixia zhang Fuping LI Mengmeng LIU Tao zhang Hongyan CHU Zhifeng LIU Institute of Advanced Manufacturing and Intelligent Technology Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China Machinery Industry Key Laboratory of Heavy Machine Tool Digital Design and Testing Technology Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China Key Laboratory of CNC Equipment Reliability Ministry of EducationSchool of Mechanical and Aerospace EngineeringJilin UniversityChangchun 130025China

Hydrophilic polymer coatings on artificial implants generate excellent tribological *** friction properties of polymer coatings are affected by salt ion ***,the atomic force microscopy(AFM)was used to show that the superlubricity was achieved between poly(vinylphosphonic acid)(PVPA)-modified Ti6Al4V and polystyrene(PS)microsphere probe lubricated with monovalent salt solutions(LiCl,NaCl,KCl,and CsCl).Considering that adhesion is an important cause of friction changes,the AFM was further utilized to obtain adhesion between friction pairs in different salt *** results indicated that the larger the cation radius in the lubricant,the smaller the adhesion,and the lower the friction coefficient of the PVPA *** electrostatic interaction between the PVPA and one-valence cations in lubricants was analyzed by the molecular dynamics(MD)simulation as it was found to be the main influencing factor of the *** analysis results of friction and adhesion indicated that by adjusting the size of cation radius in lubricant,the adhesion between the tribo-pairs can be changed,and eventually the magnitude of friction can be *** study opens up a new avenue for analyzing the friction characteristics of hydrophilic polymer coatings from the perspective of intermolecular forces.

关键词： atomic force microscopy(AFM) superlubricity poly(vinylphosphonic acid)(PVPA) cation adhesion molecular dynamics(MD)simulation

The effects of sorting by aeolian processes on the geochemical characteristics of surface materials： a wind tunnel experiment

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Frontiers of Earth Science 2018年第1期12卷 86-94页

作者： Xunming WANG Lili LANG Ting HUA caixia zhang Hui LI Key Laboratory of Water Cycle & Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Key Laboratory of Desert and Desertification Cold & Arid Regions Environmental & Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

The geochemical characteristics of aeolian and surface materials in potential source areas of dust are frequently employed in environmental reconstructions as proxies of past climate and as source tracers of aeolian sediments deposited in downwind areas. However, varia- tions in the geochemical characteristics of these aeolian deposits that result from near-surface winds are currently poorly understood. In this study, we collected surface samples from the Ala Shah Plateau （a major potential dust source area in Central Asia） to determine the influence of aeolian processes on the geochemical characteristics of aeolian transported materials. Correlation analyses show that compared with surface materials, the elements in transported materials （e.g., Cu, As, Pb, Mn, Zn, Al, Ca, Fe, Ga, K, Mg, P, Rb, Co, Cr, Na, Nb, Si, and Zr） were subjected to significant sorting by aeolian processes, and the sorting also varied among different particle size fractions and elements. Variations in wind velocity were significantly correlated with the contents of Cr, Ga, Sr, Ca, Y, Nd, Zr, Nb, Ba, and Al, and with the Zr/Al, Zr/Rb, K/Ca, Sr/Ca, Rb/Sr, and Ca/Al ratios. Given the great variation in the geochemical characteristics of materials transported under different aeolian processes relative to those of the source materials, these results indicate that considerable uncertainty may be introduced to analyses by using surface materials to trace the potential source areas of aeolian deposits that accumulate in downwind areas.

关键词： aeolian process transported material geochemistry

Simulating the effect of wind erosion on aeolian desertification process of Horqin sandy land and its significance on material cycle:a wind tunnel study

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Research in Cold and Arid Regions 2022年第1期14卷 43-53页

作者： caixia zhang JinChang Li Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China Shanxi Laboratory for Yellow River Institute of Loess PlateauShanxi UniversityTaiyuanShanxi 030006China

Samples from the Horqin sandy land were exposed to a series of wind velocities,and sink particles were collected at the end of the diffusion section of a wind *** sizes of collected samples show great variation because of the granularity difference of the surface *** original samples show lower average content of SiO_(2) and higher average content of Al _(2)O_(3),Fe_(2)O_(3),MgO,CaO,Na_(2)O,and K_(2)O than collected *** with other dust source areas in China,the Horqin sandy land had higher content of Zr,Ba,SiO_(2),Al_(2)O_(3) and K_(2)*** with the average upper continental crust(UCC)composition,surface samples were rich in the content of Y,Zr,Nb,Ba,La,*** characteristics of fine grain components of the Horqin sandy land differ from those from other dust source regions,because fine-grained particles in the Horqin sandy land were mostly derived from various local deposits formed in its unique depositional environments influenced by several tectonic activities.

关键词： sink sand wind erosion aeolian process Horqin sandy land

Construction of a Bronsted-Lewis solid acid catalyst La-PW-SiO_(2)/SWCNTs based on electron withdrawing effect of La(Ⅲ)onπbond of SWCNTs for biodiesel synthesis from esterification of oleic acid and methanol

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Chinese Journal of Chemical Engineering 2022年第4期35卷 351-362页

作者： Qing Shu Xinyuan Liu Yanting Huo Yuhui Tan caixia zhang Laixi Zou School of Chemical and Chemical Engineering Jiangxi University of Science and TechnologyGanzhou 341000China

A novel solid Bronsted-Lewis acid catalyst La-PW-SiO_(2)/SWCNTs(single-wall carbon nanotubes)was synthesized from the synergistic modification of H_(3)PW_(12)O_(40)(HPW)by single-walled carbon nanotubes functionalized with sidewall hydroxyl groups(SWCNTs–OH)and La^(3+) via sol–gel *** freshly prepared catalyst was characterized by several methods,and the catalytic activity and stability of it were studied from the esterification of oleic acid and *** showed that the highest conversion of oleic acid was 93.1%(mass)and maintained as high as 88.7%(mass)after six cycles of La-PW-SiO_(2)/*** high catalytic activity and stability of La-PW-SiO_(2)/SWCNTs can be attributed to the strong electron withdrawing effect of La^(3+) on π bond of SWCNTs,because it can facilitate the formation of a large number of strong Lewis acid ***,the reduction of catalytic activity of a solid acid catalyst due to the fact that hydration reaction of its Bronsted acid sites can be effectively ***-PW-SiO_(2)/SWCNTs can be an efficient and economical catalyst,because it shows good catalytic activity and stability.

关键词： Single-wall carbon nanotubes(SWCNTs) H_(3)PW_(12)O_(40) La^(3+) Solid Bronsted-Lewis acid catalyst Biodiesel Esterification

Intellectual Property Rights on Plant Genetic Resources:Perspective from Economics

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Chinese Journal of Population,Resources and Environment 2012年第4期10卷 59-63页

作者： zhang caixia Zhou Yanping School of Economics and Management Shandong Agricultural University Department of Economics University of Jinan College of Economics and Management Shandong University of Science and Technology

Given the existence of transaction costs,the location of property rights is an important factor in determining the incentives for efficient levels of investment at various levels of the *** paper applies some of the economic theories of property rights and industrial structure to the issues concerning the conservation of *** the expansion of Intellectual Property Rights (IPR) systems into the area of genetic resources has increased private investment in R&D process of the agriculture,it does not generate enough incentives for in situ conservation of *** solve this economic inefficiency,farmers'rights and other design of incentives and institutional arrangement should be reconsidered.

关键词： IPR genetic resources conservation of biodiversity sustainable use

Effect of brain functional recovery decoction on expression of vascular endothelial growth factor and Ang-1 protein in a rat cerebral ischemia reperfusion model

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Journal of Traditional Chinese Medicine 2017年第1期37卷 76-79页

作者： Yang Baocun zhang caixia Yang Le Yang Jing Xiao Gaiqin Department of Traditional Chinese Medicine the first Affiliated Hospital of Xi'an Jiao Tong University School of Foreign Languages Shaanxi Normal University Medical School Xi'an Jiao Tong University

OBJECTIVE: To investigate the effect of brain functional recovery decoction(BFRD) on expression of vascular endothelial growth factor(VEGF) and angiopoietin-1(Ang-1) protein in rats with cerebral ischemia reperfusion injury, and to explore the mechanism of action of ***: Using the suture-occlusion method, a Wistar rat model of focal cerebral ischemia reperfusion was established. The rats were randomly divided into treatment group, model group, and sham operation group. The treatment group was administered BFRD. In situ hybridization was used to detect VEGF m RNA expression. Immunohistochemistry was used to observe expression of Ang-1 ***: VEGF mRNA expression was greater in the model group compared with the sham operation group(P < 0.05); Ang-1 protein expression was more obvious in the treatment group than the model group(P < 0.05).CONCLUSION: BFRD promoted VEGF m RNA and Ang-1 protein expression in the brains of rats with cerebral ischemia, suggesting increased angiogenesis.

关键词： Vascular endothelial growth factors Brain ischemia Angiopoietin-1 Stroke Brain functional recovery decoction

Assessment of desertification sensitivity using an improved MEDALUS model in Northern China

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Research in Cold and Arid Regions 2024年第3期16卷 141-148页

作者： NingJing Tan caixia zhang YingYing Wu ZhenTing Wang Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China University of Chinese Academy of Sciences Beijing 100049China Research Station of Gobi Desert Ecology and Environment Northwest Institute of Eco-environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China

Assessment of land sensitivity to desertification is an important step to support desertification monitoring and *** on the Mediterranean Desertification and Land Use(MEDALUS)model,we defined four quality indicators(soil,climate,vegetation and management)to evaluate the sensitivity of land in northern China to *** improved MEDALUS via excluding cities from the areas at risk of desertification by means of defining a threshold value for population *** framework,validated in northern China,further optimizes the model to link priority areas and land restoration programmed to support desertification *** found that the four indicators influenced and restricted each other,which jointly affected the distribution of desertification sensitivity in northern *** spatial distribution of sensitivity in northern China showed large regional differences,with clear boundaries and concentrated distributions of regions with high and low sensitivity;the overall sensitivity decreased,with some areas rated as having moderate,severe,and extremely severe sensitivity changing to slight sensitivity;and the influence weight was much higher for the management quality index than for the climate,vegetation,and soil *** suggests that management was the main factor that affected desertification sensitivity in northern China,and that climate factors exacerbated sensitivity,but the factors that are driving the spatial heterogeneity of the influencing factors need further study。

关键词： Desertification Sensitivity MEDALUS Factor analysis Northern China

Protective effects of acupuncture and LGNHFD on expressions of vascular endothelial growth factor, basic fibroblast growth factor,and cluster of differentiation 34 in rats with cerebral ischemia-reperfusion injury

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Journal of Traditional Chinese Medicine 2021年第3期41卷 463-469页

作者： YANG Le YANG Baocun zhang caixia TONg Jie FENG Geli XIAO Gaiqin Department of Traditional Chinese Medicine the first Affiliated Hospital of Xi'an Jiaotong UniversityXi'an 710061China School of Foreign Languages Shaanxi Normal UniversityXi'an Shaanxi Normal UniversityXi'an 710062China Newcastle University Newcastle upon Tyne NE17RUUK 不详

OBJECTIVE: To investigate the protective effects of electroacupuncture and LGNHFD on cerebral ischemia-reperfusion injury, and their effects on the expression of cluster of differentiation 34(CD 34), vascular endothelial growth factor(VEGF), and basic fibroblast growth factor(b FGF) in the peripheral tissue of the cerebral ischemic semi-dark zone in *** influence and mechanism of ***: Healthy male Sprague-Dawley rats were randomly divided into the sham operation group, model group, Traditional Chinese Medicine (TCM) group, electroacupuncture group, and acupuncture group. The cerebral ischemia model was prepared by middle artery occlusion. The electroacupuncture and TCM groups received electroacupuncture at the "Neiguan(PC6)", "Baihui(GV20)", and "Renzhong(GV26)" acupoints from 4 h after modeling, once daily for 14 d. After modeling,the acupuncture and TCM groups were administered LGNHFD once daily for 14 d. After treatment,the infarct volume and regional cerebral blood flow(r CBF) were measured in each group, the expression of CD34 in the surrounding ischemic penumbra was determined using immunohistochemistry,and the expression of angiogenesis-related factors in the ischemic hemisphere was detected by western ***: Compared with the sham operation group, r CBF was significantly decreased(P < 0.01)and cerebral infarction volume was significantly increased(P < 0.01) in the model group at four time points(5 min and 3, 7, and 14 d after modeling). At three postoperative time points(3, 7, and 14 d), the number of CD34 + cells in the model group were significantly increased(P < 0.01), and the relative expression levels of VEGF, b FGF, and CD34+ in the ischemic hemisphere were significantly increased(P < 0.01, P < 0.05). Compared with the model group, the r CBF of the acupuncture group was significantly increased at 3, 7, and 14 d after intervention(P < 0.01), while the r CBF of the electroacupuncture and TCM groups was significantly increased a

关键词： Electroacupuncture LGNHFD brain ischemia antigens CD34 vascular endothelial growth factors fibroblast growth factors