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Influence of the variation in rural population on farmland preservation in the rapid urbanization area of China

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Journal of Geographical Sciences 2021年第9期31卷 1365-1380页

作者： zhang Mingyu CHEN Qiuxiao zhang kewei Department of Regional and Urban Planning Zhejiang UniversityHangzhou 310058China School of Spatial Planning and Design Zhejiang University City CollegeHangzhou 310015China

In the past 40 years,cultivated land has faced the continued anthropogenic interference,which has become a significant issue for cultivated land preservation during rapid *** purpose of this research was to reveal the spatio-temporal evolutionary characteristics of cultivated land and the correlation between rural population variation and farmland change in *** county-level administrative units in Zhejiang Province were selected as the study area wherein spatio-temporal evolution comparative analysis for every 5 years from 2000 to 2015 was *** study used the pool method to estimate the impacts of the rural population variation,average slope,average elevation,rural residential disposable income,primary industry proportion,and road density on farmland utilization efficiency from the spatial perspective,which is represented by landscape metrics including the mean patch size,edge density,area weighted mean shape index,and area weighted mean patch fractal *** study showed that the cultivated land landscape index continued to rise after 2000 and then started decreasing after 2010,indicating a reduction in human interference after *** spatial variation of rural population of all county-level administrative units decreased from 2000 to 2010,and 62%of them began to increase after *** regression analysis results showed that the spatial variation of rural population was significantly and negatively correlated with the cultivated land landscape while the rural residential disposable income,average slope and primary industry proportion were all significantly and positively related to the cultivated land landscape *** results implied that the loss of the agricultural labor force and the difficulty of sloping farmlands adapting to mechanized farming were unconducive to farmland utilization efficiency improvement,and the increase in nonagricultural activities in rural areas would increase the difficulty of cultivated land p

关键词： rural population farmland landscape metrics Zhejiang Province

Mechanism of Locust Air Posture Adjustment

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Journal of Bionic Engineering 2015年第3期12卷 418-431页

作者： Diansheng Chen kewei Chen Ziqiang zhang Benguang zhang Robotic Institute in School of Mechanical Engineering and Automation Beihang University Beijing 100191 China

Stimulated locusts often tumble during the jumping process. Locusts can also recover their bodies in the air for flight or landing stability. To increase jumping distance and avoid landing collision of bio-inspired jumping robots, the mechanism of air posture adjustment of locusts is examined in this research. This mechanism can be used to improve the stability of robot. The abdomen swings, wing motions, and the variations in body angle are recorded by a high-speed camera when locusts free fall in air with normal or upside-down initial posture. Results indicate that the wings and abdomen are mainly utilized for air posture adjustment. Moreover, abdomen swing and forewing rotation have positive effects on body pitch. However, locusts have dif- ficulty in recovering their bodies from the upside-down posture without wings, although the body pitch caused by unpredictable perturbation in air can be compensated through abdomen swing. Consequently, body roll is attributed to the wing motion, which is related to two factors, namely, the different flapping amplitudes of the wings on both sides, and the different flapping velocities of wings during the upstroke and downstroke periods. This research may provide reference for the design of jumping robots.

关键词： locusts air posture adjustment abdomen swing asymmetric flapping wings

Approximations for modulus of gradients and their applications to neighborhood filters

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Frontiers of Mathematics in China 2013年第4期8卷 761-782页

作者： Yan CHEN Zhuangji WANG kewei zhang College of Resource and Environment China Agricultural University Beijing 100193 China Department of Agronomy Iowa State University Ames IA 50011USA School of Mathematical Sciences University of Nottingham University Park Nottingham NG7 2RD UK

We define an integral approximation for the modulus of the gradient ｜ u（x）｜ for functions f： Ω C Rn → R by modifying a classical result due to Calderon and Zygmund. Our integral approximations are more stable than the pointwise defined derivatives when applied to numerical differentiation for discrete data. We apply our results to design and analyse neighborhood filters. These filters correspond to well-behaved nonlinear heat equations with the conductivity decreasing with respect to the modulus of gradient ｜ u（x）｜. We also show some numerical experiments and evaluate the effectiveness of our filters.

关键词： BMO modulus of gradient harmonic analysis and PDE neighborhood filter image processing

Exploring a balance between strength and ductility of hexagonal BN nanoplatelet reinforced ZK61 magnesium composite

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Journal of Magnesium and Alloys 2024年第5期12卷 1899-1910页

作者： kewei zhang Xiaolong Lu Yufeng Sun Shaokang Guan Yao Chen School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China Key Laboratory of Advanced Magnesium Alloys in Henan Province Zhengzhou UniversityZhengzhou 450002China Key Laboratory of Advanced Materials Processing&Mold Ministry of EducationZhengzhou 450002China School of Mechanical and Electrical Engineering Soochow UniversitySuzhou 215021China

The practical applications of magnesium(Mg)alloys are usually beset by their relatively low strength and limited *** we attempt to fabricate hexagonal BN nanoplatelet(BNNP)reinforced ZK61 magnesium composites using a combination of spark plasma sintering and friction stir *** resulting composites exhibit microstructural characteristics of homogeneous dispersion of BNNP in Mg matrix with refined equiaxed grains and(0002)basal texture roughly surrounding the pin column *** electron microscopy observation illustrates that trace amounts of Mg_(3)N_(2)and MgB_(2)form at BNNP-Mg interface,in which Mg_(3)N_(2)locates at the basal plane of a BNNP and MgB_(2)grows at its open *** spatial distribution of Mg_(3)N_(2)and MgB_(2)facilitates interfacial wetting and stronger BNNP-Mg interface in such a way that interfacial products act as anchors bonding between *** comparison with monolithic ZK61 alloy,the BNNP/ZK61 composites display simultaneous improvements in yield strength,hardness and ductility,achieving good strength-ductility *** research is expected to shed some light on BNNP potentials for designing and producing magnesium composites with high strength and good ductility.

关键词： BN nanoplatelet Magnesium composite Strength Ductility Spark plasma sintering Friction stir processing

Zinc-catecholete frameworks biomimetically grown on marine polysaccharide microfibers for soft electronic platform

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Nano Research 2023年第1期16卷 1296-1303页

作者： Kai Liu Mingxin zhang Xinxin Du Anqin Zhou Bin Hui Yanzhi Xia kewei zhang State Key Laboratory of Bio-Fibers and Eco-Textiles Collaborative Innovation Center for Marine Biomass FibersMaterials and Textiles of Shandong ProvinceCollege of Materials Science and EngineeringInstitute of Marine Biobased MaterialsQingdao UniversityQingdao 266071China

Integrating functional nanomaterials on nonplanar organisms has emerged as a rising technology,while significant mismatch would cause interface failure and poor ***,we demonstrate a facile strategy to assemble crystalline catecholate frameworks with honeycomb lattice on seaweed-derived polysaccharide microfibers,which is expected to form biomimetic connections and maintain durable *** physiological coagulation,well-aligned ZnO nanoarrays are tightly attached on alginate fibers,which is fractionally adopted as sacrifice for heteroepitaxial growth of zinc-catecholate frameworks(Zn3(HHTP)2).Benefiting from amplification effect of in-situ formed heterojunctions,promoted interfacial charge transfer is achieved,which allows for fabricating broadband *** with high porosity for gas adsorption,the heteroepitaxial catecholate framework further enables its use as highly selective ppb-level triethylamine *** work provides a promising strategy for heteroepitaxial growth of catecholate frameworks on organo-substrates and opens new applications in wearable sensor platform based on comfortable biofibers.

关键词： metal-organic frameworks epitaxial growth heterostructures sensors biofibers

An efficient CuZr-based metallic glasses electrode material for electrocatalytic degradation of azo dyes

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Journal of Environmental Sciences 2024年第2期136卷 537-546页

作者： Zhiwang Deng Bowen Zhao Songtao Li Zhengkun Li Shiming zhang kewei zhang Zhengwang Zhu Taiyuan University of Science and Technology School of materials science and engineeringTaiyuan 030024China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Chinese Academy of Sciences Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Qingdao Yunlu Advanced Materials Technology Co. Ltd.Qingdao 266232China

Metallic glasses have received a lot of attention on wastewater treatment due to their unique atomic structure,and the use of metallic glasses as electrodes has produced unexpected electrocatalytic degradation effects for many pollutants through combining with electrochemical ***,it still is a formidable challenge to find a metallic glass electrode material with both efficient and clean for the catalytic degradation of *** this work,the Cu_(55)Zr_(45)metallic glassy ribbons are used as an electrode to degrade azo dyes and show the excellent degradation effect,which can reach 95.6%within 40 *** the degradation process,almost no additives are produced and Cu_(55)Zr_(45)metallic glassy ribbons have excellent effects under different pH ***,it exhibits good stability for degradation efficiency during the 8 cycle degradation tests of the amorphous alloy *** the copper nanoparticles are exposed on the surface of the ribbons,the oxidized copper obtained synergistically produce activated radicals is the primary degradation mechanism,where the auxiliary degradation mechanisms include electron transfer and the promotion of active *** research develops a new type of electrode material for wastewater treatment,and the economy and high efficiency of Cu55Zr45metallic glass endow it the expandable functional applications.

关键词： Metallic glasses Azo dyes Electrocatalytic Degradation Oxidized copper

Interfacial energy barrier tuning of hierarchical Bi_(2)O_(3)/WO_(3) heterojunctions for advanced triethylamine sensor

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Journal of Advanced Ceramics 2022年第12期11卷 1860-1872页

作者： Mingxin zhang Kai LIU Xingmin zhang Bingbing WANG Xinru XU Xinxin DU Chao YANG kewei zhang College of Materials Science and Engineering State Key Laboratory of Bio-Fibers and Eco-TextilesCollaborative Innovation Center for Marine Biomass FibersMaterials and Textiles of Shandong ProvinceQingdao UniversityQingdao 266071China

Traditional triethylamine(TEA)sensors suffer from the drawback of serious cross-sensitivity due to the low charge-transfer ability of gas-sensing ***,an advanced anti-interference TEA sensor is designed by utilizing interfacial energy barriers of hierarchical Bi_(2)O_(3)/WO_(3) *** from abundant slit-like pores,desirable defect features,and amplification effect of heterojunctions,the sensor based on Bi_(2)O_(3)/WO_(3) composite with 40%Bi_(2)O_(3)(0.4-Bi_(2)O_(3)/WO_(3))demonstrates remarkable performance in terms of faster response/recovery time(1.7-fold/1.2-fold),higher response(2.1-fold),and lower power consumption(30℃-decrement)as compared with the pristine WO_(3) ***,the composite sensor exhibits long-term stability,reproducibility,and negligible response towards interfering molecules,indicating the promising potential of Bi_(2)O_(3)/WO_(3) heterojunctions in anti-interference detection of low-concentration TEA in real *** work not only offers a rational solution to design advanced gas sensors by tuning the interfacial energy barriers of heterojunctions,but also provides a fundamental understanding of hierarchical Bi_(2)O_(3) structures in the gas-sensing field.

关键词： Bi_(2)O_(3)/WO_(3) heterojunctions hierarchical structures triethylamine(TEA) gas sensors

Spatially distributed cytokinins:Metabolism,signaling,and transport

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Plant Communications 2024年第7期5卷 52-67页

作者： Jiangzhe Zhao Jingqi Wang Jie Liu Penghong zhang Guzel Kudoyarova Chang-Jun Liu kewei zhang Zhejiang Provincial Key Laboratory of Biotechnology on Specialty Economic Plants College of Life SciencesZhejiang Normal UniversityJinhuaZhejiang 321004P.R.China Ufa Institute of Biology Ufa Federal Research CenterRASProspekt Oktyabrya 69Ufa 450054Russia Biology Department Brookhaven National LaboratoryUptonNY 11973USA

Cytokinins are mobile phytohormones that regulate plant growth,development,and environmental *** major cytokinin species include isopentenyl adenine(iP),trans-zeatin(tZ),cis-zeatin(cZ),and dihydrozeatin(DZ).The spatial distributions of different cytokinin species in different organelles,cells,tissues,and organs are primarily shaped by biosynthesis via isopentenyltransferases(IPT),cytochrome P450 monooxygenase,and 50-ribonucleotide phosphohydrolase and by conjugation or catabolism via glycosyltransferase or cytokinin oxidase/*** bind to histidine receptor kinases in the endoplasmic reticulum or plasma membrane and relay signals to response regulators in the nucleus via shuttle proteins known as histidine phosphotransfer *** movements of cytokinins from sites of biosynthesis to sites of signal perception usually require long-distance,intercellular,and intracellular *** the past decade,ATP-binding cassette(ABC)transporters,purine permeases(PUP),AZA-GUANINE RESISTANT(AZG)transporters,equilibrative nucleoside transporters(ENT),and Sugars Will Eventually Be Exported transporters(SWEET)have been characterized as involved in cytokinin transport *** review begins by introducing the spatial distributions of various cytokinins and the subcellular localizations of the proteins involved in their metabolism and *** focus on an inventory of the characterized transporters involved in cytokinin compartmentalization,including long-distance,intercellular,and intracellular transport,and the regulation of the spatial distributions of cytokinins by environmental *** directions for cytokinin research are also discussed.

关键词： cytokinin biosynthesis transporter signal transduction environmental changes

Defect promoted photothermoelectric effect in densely aligned ZnO nanorod arrays for self-powered position-sensitive photodetection

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Journal of Materiomics 2022年第3期8卷 693-701页

作者： Xinxin Du Weiliang Tian Ziqi zhang Bin Hui Jiahui Pan Jianhua Sun kewei zhang State Key Laboratory of Bio-Fibers and Eco-Textiles Collaborative Innovation Center for Marine Biomass FibersMaterials and Textiles of Shandong ProvinceCollege of Materials Science and EngineeringInstitute of Marine Biobased MaterialsQingdao UniversityQingdao266071China Key Laboratory of Chemical Engineering in South Xinjiang College of Life ScienceTarim UniversityAlar843300China Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology Guangxi UniversityNanning530004China

Sustainable light energy from ambient environment has attracted particular attention to meet the evergrowing need of small-scale *** modulation of intercorrelated thermal and electronic transport is one of the crucial aspects for reliable photothermoelectric ***,a defectpromoted photothermoelectric effect is demonstrated in densely aligned ZnO nanorod array with rich lattice *** defect-rich ZnO device delivers high electrical conductivity and large Seebeck coefficient to enable significant improvement of photothermoelectric energy conversion and self-powered *** position sensitivity reaches approximately 0.19 mV mm^(-1),and the temperature gradient induced electric field makes up for the suppression in the photothermoelectric *** synergism between intrinsic defects and extra temperature field plays an important role in promoting the photothermoelectric properties of dense ZnO nanorod *** study is interesting for interpreting the thermo-phototronic phenomena as well as demonstrating the possibility of defect engineering and phonon engineering to enable highly efficient light energy scavenging and self-powered photodetection.

关键词： Defect-rich ZnO Photodetectors Light energy Photothermoelectric Self-powered