检索结果-南通市图书馆

AFM probe for measuring~10^(−5)ultra-low friction coefficient:Design and application

在线全文

学校读者我要写书评

暂无评论

Friction 2024年第1期12卷 64-73页

作者： Yushan CHEN liang JIANG Linmao QIAN Tribology Research Institute State Key Laboratory of Traction PowerSouthwest Jiaotong UniversityChengdu 610031China

Superlubricity provides a novel approach to addressing friction and wear issues in mechanical systems.However,little is known regarding improving the atomic force microscope(AFM)friction coefficient measurement resolution.Accordingly,this study established the theoretical formula for the AFM friction coefficient measurement and deduced the measurement resolution.Then,the formula was applied to the AFM probe with a rectangular cross-section cantilever.The measurement resolution is associated with the dimensional properties of the AFM probe,the mechanical properties of the cantilever material,the properties of the position-sensitive detector(PSD),and probably the anti-vibration performance of the AFM.It is feasible to make the cantilever as short as possible and the tip as high as possible to improve the measurement resolution.An AFM probe for measuring an ultra-low friction coefficient was designed and fabricated.The cantilever’s length,width,and thickness are 50,35,and 0.6μm,respectively.The tip height is 23μm.The measurement resolution can reach 7.1×10^(−6) under the maximum normal force.Moreover,the AFM probe was applied to measure the superlubricity between graphene layers.The friction coefficient is 0.00139 under 853.08 nN.This work provides a promising method for measuring a~10^(−5) friction coefficient of superlubricity.

关键词： atomic force microscope(AFM) superlubricity friction coefficientμ probe

Emodin suppresses alkali burn-induced corneal inflammation and neovascularization by the vascular endothelial growth factor receptor 2 signaling pathway

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Traditional Chinese Medicine 2024年第2期44卷 268-276页

作者： ZHENG Xueying GUO liang LAI Siyi LI Fengyue liang Mingli LIU Wanting MENG Chun LIU Guanghui Department of Bioengineering College of Biological Science and BiotechnologyFuzhou UniversityFuzhou 350104China Eye Institute of Integrated Chinese and Western Medicine Fujian University of Traditional Chinese MedicineFuzhou 350004China Department of Ophthalmology Affiliated People's Hospital(Fujian Provincial People's Hospital)Fujian University of Traditional Chinese MedicineFuzhou 350004China

OBJECTIVE:To investigate the effects of emodin on alkali burn-induced corneal inflammation and neovascularization.METHODS:The ability of emodin to target vascular endothelial growth factor receptor 2(VEGFR2)was predicted by molecular docking.The effects of emodin on the invasion,migration,and proliferation of human umbilical vein endothelial cells(HUVEC)were determined by cell counting kit-8,Transwell,and tube formation assays.Analysis of apoptosis was performed by flow cytometry.CD31 levels were examined by immunofluorescence.The abundance and phosphorylation state of VEGFR2,protein kinase B(Akt),signal transducer and activator of transcription 3(STAT3),and P38 were examined by immunoblot analysis.Corneal alkali burn was performed on 40 mice.Animals were divided randomly into two groups,and the alkali-burned eyes were then treated with drops of either 10μM emodin or phosphate buffered saline(PBS)four times a day.Slitlamp microscopy was used to evaluate inflammation and corneal neovascularization(CNV)in all eyes on Days 0,7,10,and 14.The mice were killed humanely 14 d after the alkali burn,and their corneas were removed and preserved at-80℃ until histological study or protein extraction.RESULTS:Molecular docking confirmed that emodin was able to target VEGFR2.The findings revealed that emodin decreased the invasion,migration,angiogenesis,and proliferation of HUVEC in a dose-dependent manner.In mice,emodin suppressed corneal inflammatory cell infiltration and inhibited the development of corneal neovascularization induced by alkali burn.Compared to those of the PBS-treated group,lower VEGFR2 expression and CD31 levels were found in the emodintreated group.Emodin dramatically decreased the expression of VEGFR2,p-VEGFR2,p-Akt,p-STAT3,and p-P38 in VEGF-treated HUVEC.CONCLUSION:This study provides a new avenue for evaluating the molecular mechanisms underlying corneal inflammation and neovascularization.Emodin might be a promising new therapeutic option for corneal alkali burns.

关键词： alkali burn emodin corneal inflammation corneal neovascularisation vascular endothelial growth factor receptor-2 signal transduction

Nest decoration:Black feathers prevent Crested Mynas from nest usurpation

在线全文

学校读者我要写书评

暂无评论

Avian Research 2024年第2期15卷 292-297页

作者： Jinmei Liu Wei liang Ministry of Education Key Laboratory for Ecology of Tropical Islands Key Laboratory of Tropical Animal and Plant Ecology of Hainan ProvinceCollege of Life SciencesHainan Normal UniversityHaikou571158China

Nests are important structures for birds to raise their offspring and for signaling.Many birds incorporate feathers into the nest,since feathers were traditionally thought to serve the function of insulation.Hypotheses in recent years have considered that some birds place feathers in conspicuous locations in the nest for decoration to trigger a fear response in the competitors.In this study,we investigated whether decorative feathers could deter nest usurpation by Crested Mynas(Acridotheres cristatellus)by manipulating nest box contents.The results revealed that Crested Mynas preferred black feathers to white feathers as decorations and occupied nest boxes decorated with black feathers significantly less than those decorated with white feathers,suggesting that black decorative feathers in the nest could be more effective in preventing nest usurpation by Crested Mynas and that white decorative feathers may have other functions.The black feathers in the nest are prominently placed at the edge of the nest to convey the message that“this nest is occupied”or“the owner of this nest has been preyed upon”to visitor Crested Mynas,thus effectively preventing them from usurping the nest at a later stage.

关键词： Extended phenotype Feathers Nest decoration Nest usurpation

Seasonal increase in nest defense,but not egg rejection,in a cuckoo host

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Avian Research 2024年第1期15卷 50-54页

作者： Bo Zhou Wei liang Ministry of Education Key Laboratory for Ecology of Tropical Islands Key Laboratory of Tropical Animal and Plant Ecology of Hainan ProvinceCollege of Life SciencesHainan Normal UniversityHaikou 571158China Institute of Biological Resources Jiangxi Academy of ScienceNanchang 330096China

The interactions between avian brood parasites and their hosts provide an informative and easy-to-handle system for studying coevolution.Avian brood parasitism reduces the reproductive success of hosts,and thus,hosts have evolved anti-parasitic strategies,such as rejecting parasitic eggs and adopting aggressive nest defense strategies,to avoid the cost brought on by brood parasitism.To test whether host anti-parasitic strategies are adjusted with the risk of being parasitized when the breeding seasons of brood parasites and hosts are not synchronous,we conducted a field experiment assessing nest defense and egg recognition behaviors of the Isabelline Shrike(Lanius isabellinus),a host of the Common Cuckoo(Cuculus canorus).In the local area,the host Isabelline Shrike begins to breed in April,whereas the summer migratory Common Cuckoo migrates to the local area in May and begins to lay parasitic eggs.Results showed that nest defense behaviors of the Isabelline Shrike increases significantly after cuckoo arrival,showing higher aggressiveness to cuckoo dummies,with no significant difference in attack rates among cuckoo,sparrowhawk and dove dummies,but their egg rejection did not change significantly.These results imply that Isabelline Shrikes may adjust their nest defense behavior,but not egg rejection behavior,with seasonality.

关键词： Aggression Anti-parasite strategy Egg rejection Mismatch cuckoo parasitism Nest defense

The low Mach number limit of non-isentropic magnetohydrodynamic equations with large temperature variations in bounded domains

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2024年第4期67卷 787-818页

作者： Min liang Yaobin Ou School of Mathematics Renmin University of ChinaBeijing 100872China

This paper verifies the low Mach number limit of the non-isentropic compressible magnetohydrodynamic(MHD)equations with or without the magnetic diffusion in a three-dimensional bounded domain when the temperature variation is large but finite.The uniform estimates of strong solutions are established in a short time interval independent of the Mach number,provided that the slip boundary condition for the velocity and the Neumann boundary condition for the temperature are imposed and the initial data is well-prepared.

关键词： low Mach number limit non-isentropic compressible magnetohydrodynamic equations large temperature variations bounded domains

HgaNets:Fusion of Visual Data and Skeletal Heatmap for Human Gesture Action Recognition

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第4期79卷 1089-1103页

作者： Wuyan liang Xiaolong Xu School of Internet of Things Nanjing University of Posts and TelecommunicationsNanjing210023China School of Computer Science Nanjing University of Posts and TelecommunicationsNanjing210023China

Recognition of human gesture actions is a challenging issue due to the complex patterns in both visual andskeletal features. Existing gesture action recognition (GAR) methods typically analyze visual and skeletal data,failing to meet the demands of various scenarios. Furthermore, multi-modal approaches lack the versatility toefficiently process both uniformand disparate input patterns.Thus, in this paper, an attention-enhanced pseudo-3Dresidual model is proposed to address the GAR problem, called HgaNets. This model comprises two independentcomponents designed formodeling visual RGB (red, green and blue) images and 3Dskeletal heatmaps, respectively.More specifically, each component consists of two main parts: 1) a multi-dimensional attention module forcapturing important spatial, temporal and feature information in human gestures;2) a spatiotemporal convolutionmodule that utilizes pseudo-3D residual convolution to characterize spatiotemporal features of gestures. Then,the output weights of the two components are fused to generate the recognition results. Finally, we conductedexperiments on four datasets to assess the efficiency of the proposed model. The results show that the accuracy onfour datasets reaches 85.40%, 91.91%, 94.70%, and 95.30%, respectively, as well as the inference time is 0.54 s andthe parameters is 2.74M. These findings highlight that the proposed model outperforms other existing approachesin terms of recognition accuracy.

关键词： Gesture action recognition multi-dimensional attention pseudo-3D skeletal heatmap

The Boundary Element Method for Ordinary State-Based Peridynamics

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2024年第6期139卷 2807-2834页

作者： Xue liang Linjuan Wang State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering ScienceCollege of EngineeringPeking UniversityBeijing100871China CAPT-HEDPS and IFSA Collaborative Innovation Center of MoECollege of EngineeringPeking UniversityBeijing100871China School of Astronautics Beihang UniversityBeijing100191China

The peridynamics(PD),as a promising nonlocal continuum mechanics theory,shines in solving discontinuous problems.Up to now,various numerical methods,such as the peridynamic mesh-free particlemethod(PD-MPM),peridynamic finite element method(PD-FEM),and peridynamic boundary element method(PD-BEM),have been proposed.PD-BEM,in particular,outperforms other methods by eliminating spurious boundary softening,efficiently handling infinite problems,and ensuring high computational accuracy.However,the existing PD-BEM is constructed exclusively for bond-based peridynamics(BBPD)with fixed Poisson’s ratio,limiting its applicability to crack propagation problems and scenarios involving infinite or semi-infinite problems.In this paper,we address these limitations by introducing the boundary element method(BEM)for ordinary state-based peridynamics(OSPD-BEM).Additionally,we present a crack propagationmodel embeddedwithin the framework ofOSPD-BEM to simulate crack propagations.To validate the effectiveness of OSPD-BEM,we conduct four numerical examples:deformation under uniaxial loading,crack initiation in a double-notched specimen,wedge-splitting test,and threepoint bending test.The results demonstrate the accuracy and efficiency of OSPD-BEM,highlighting its capability to successfully eliminate spurious boundary softening phenomena under varying Poisson’s ratios.Moreover,OSPDBEMsignificantly reduces computational time and exhibits greater consistencywith experimental results compared to PD-MPM.

关键词： Ordinary state-based peridynamics boundary element method crack propagation fracture toughness

Highly Dispersed Cobalt Nanoparticles Embedded in Nitrogen-Doped Graphitized Carbon for Fast and Durable Potassium Storage

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano-Micro Letters 2021年第2期13卷 1-12页

作者： Xiaodong Shi Zhenming Xu Cheng Han Runze Shi Xianwen Wu Bingan Lu Jiang Zhou shuquan liang School of Materials Science and Engineering Central South UniversityChangsha 410083People’s Republic of China University of Michigan-Shanghai Jiao Tong University Joint Institute Shanghai Jiao Tong UniversityShanghai 200240People’s Republic of China Harvard John.A.Paulson School of Engineering and Applied Sciences Harvard University29 Oxford StreetCambridgeMA 02138USA School of Chemistry and Chemical Engineering Jishou UniversityJishou 416000People’s Republic of China School of Physics and Electronics State Key Laboratory of Advanced Design and Manufacturing for Vehicle BodyHunan UniversityChangsha 410082People’s Republic of China Key Laboratory of Electronic Packaging and Advanced Functional Materials of Hunan Province Central South UniversityChangsha 410083People’s Republic of China

Potassium-ion batteries(KIBs)have great potential for applications in large-scale energy storage devices.However,the larger radius of K+leads to sluggish kinetics and inferior cycling performance,severely restricting its practical applicability.Herein,we propose a rational strategy involving a Prussian blue analogue-derived graphitized carbon anode with fast and durable potassium storage capability,which is constructed by encapsulating cobalt nanoparticles in nitrogen-doped graphitized carbon(Co-NC).Both experimental and theoretical results show that N-doping effectively promotes the uniform dispersion of cobalt nanoparticles in the carbon matrix through Co-N bonds.Moreover,the cobalt nanoparticles and strong Co-N bonds synergistically form a threedimensional conductive network,increase the number of adsorption sites,and reduce the diffusion energy barrier,thereby facilitating the adsorption and the diffusion kinetics.These multiple effects lead to enhanced reversible capacities of 305 and 208.6 mAh g^−1 after 100 and 300 cycles at 0.05 and 0.1 A g^−1,respectively,demonstrating the applicability of the Co-NC anode for KIBs.

关键词： Cobalt nanoparticles Nitrogen-doped graphitized carbon Co-N bonds Cycling stability Potassium-ion batteries

Endomembrane-biased dimerization of ABCG16 and ABCG25 transporters determines their substrate selectivity in ABA-regulated plant growth and stress responses

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2024年第3期17卷 478-495页

作者： Yeling Zhou Yuzhu Wang Dong Zhang Jiansheng liang institute of Plant and Food Science Department of BiologySchool of Life SciencesSouthern University of Science and Technology(SUSTech)Shenzhen 518055China Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes Southern University of Science and Technology(SUSTech)Shenzhen 518055China jiangsu Key Laboratory of Crop Genetics and Physiology/Co-lnnovation Center for Modern Production Technology of Grain Crops Key Laboratory of Plant Functional Genomics of the Ministry of EducationYangzhou UniversityYangzhou 225009China

ATP-binding cassette(ABC)transporters are integral membrane proteins that have evolved diverse func-tions fulfilled via the transport of various substrates.In Arabidopsis,the G subfamily of ABC proteins is particularly abundant and participates in multiple signaling pathways during plant development and stress responses.In this study,we revealed that two Arabidopsis ABCG transporters,ABCG16 and ABCG25,engage in ABA-mediated stress responses and early plant growth through endomembrane-specific dimerization-coupled transport of ABA and ABA-glucosyl ester(ABA-GE),respectively.We first revealed that ABCG16 contributes to osmotic stress tolerance via ABA signaling.More specifically,ABCG16 induces cellular ABA efflux in both yeast and plant cells.Using FRET analysis,we showed that ABCG16 forms oblig-atory homodimers for ABA export activity and that the plasma membrane-resident ABCG16 homodimers specifically respond to ABA,undergoing notable conformational changes.Furthermore,we demonstrated that ABCG16 heterodimerizes with ABCG25 at the endoplasmic reticulum(ER)membrane and facilitates the ER entry of ABA-GE in both Arabidopsis and tobacco cells.The specific responsiveness of the ABCG16-ABCG25 heterodimer to ABA-GE and the superior growth of their double mutant support an inhib-itory role of these twoABCGs in early seedling establishment via regulation of ABA-GE translocation across the ER membrane.Our endomembrane-specific analysis of the FRET signals derived from the homo-or heterodimerized ABcG complexes allowed us to link endomembrane-biased dimerization to the transloca-tion of distinct substrates by ABcG transporters,providing a prototypic framework for understanding the omnipotence of ABcG transporters in plant development and stress responses.

关键词： abscisic acid ABCG transporter dimerization endomembrane substrate selectivity