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Mechanisms behind the environmental sensitivity of carbon fiber reinforced polytetrafluoroethylene(PTFE)

Friction 2024年第5期12卷 997-1015页

作者： Pontus JOHANSSON P.MARKLUND M.BJORLING y.shi Division of Machine Element LuleåUniversity of TechnologyLuleåSE-97187Sweden

Carbon fiber reinforced polytetrafluoroethylene (CF/PTFE) composites are known for their exceptional tribological performance when sliding against steel or cast iron in inert gas environments. Compared to experiments in humid air, about an order of magnitude lower wear rate and several times lower coefficient of friction have been reported for tests conducted in dry nitrogen and hydrogen. Moreover, trace moisture has been shown to affect the friction and wear significantly of this tribosystem, although a possible effect of oxygen cannot be ruled out due to uncertainties regarding the oxygen concentrations. While several studies have pointed out the environmental sensitivity of CF/PTFE, the understanding of the underlying mechanisms are very limited. The objective of this research is to investigate the individual and combined effect of oxygen and moisture on the tribological behavior of CF/PTFE sliding against steel. Additionally, this study aims to elucidate the underlying mechanisms that govern the environmental sensitivity of the system. Climate-controlled three-pin-on-disc experiments were conducted in nitrogen atmospheres at various concentrations of oxygen and moisture. The tribological results clearly demonstrate that both moisture and oxygen contribute to increased friction and wear. However, the adverse effect was much more pronounced for oxygen than moisture. A qualitative method was developed to estimate the tribofilm coverage on the CF/PTFE surface. Results showed strong correlation between high coverage of strongly adhered tribofilm and low wear rate. Moreover, a loosely adhered tribofilm was observed on top of the CF/PTFE surface in presence of moisture. FTIR analysis indicated that the loosely adhered tribofilm found in the moisture-enriched environment contained a significant amount of adsorbed water, which may explain the lower coefficient of friction in presence of moisture compared to oxygen. The adsorbed water in the loosely adhered tribofilm coul

关键词： polymer composite tribofilm tribochemistry atmosphere

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A detailed comparison of the composition of(RE)-Ba-Cu-O-Ag bulk superconductors

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Superconductivity 2024年第1期9卷 87-94页

作者： J.V.J.Congreve y.shi A.R.Dennis H.Druiff N.C.Tutt D.A.Cardwell J.H.Durrell Department of Engineering University of CambridgeCambridgeUK

The homogeneity of the microstructure and composition are critical in determining the properties of rare earthbarium‐cuprate,single grain bulk superconductors[(RE)BCO].The magnitude of the trapped magnetic field achieveable in these technologically important materials,in particular,is influenced heavily by the size and distribution of(RE)_(2)BaCuO_(x)(RE‐211)flux pinning inclusions in the bulk microstructure,whereas the size and distribution of silver agglomerates present within the bulk superconducting matrix correlate directly with improved mechanical *** careful engineering,these materials have significant potential for application in range of devices related to energy storage,medicine,electro‐magnetic machinery and microelectronic *** of(RE)BCO bulk superconductors typically involves heating a powder compact above its peritectic decomposition temperature followed by slow cooling to facilitate the growth of a single ***(RE)BCO composition has a different peritectic temperature and growth rate,which,therefore,necessitates different requirements in the heating *** fabrication temperature and growth rate,for example,may have an effect on the RE‐211 and silver distribution,which may,in turn,affect the superconducting properties of the resulting single *** this work we compare the distributions of silver and RE‐211 in the single grain microstructures of yBCOAg,GdBCO‐Ag,EuBCO‐Ag and SmBCO‐Ag bulk superconductors using optical microscopy,scanning electron microscopy and energy dispersive X‐ray *** observe that the distributions are very similar along both the a/b‐axis and c‐axis of these *** suggests that factors other than the maximum temperature used to achieve peritectic decomposition and the rate of single grain growth are particularly influential in determining the properties of the as‐processed samples in the top seeded melt growth *** observation demonstrates there is freedom to us

关键词： yBCO‐Ag GdBCO‐Ag SmBCO‐Ag EuBCO‐Ag Composition Bulk superconductor

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Detection of diabetic retinopathy in its early stages using textural features of optical coherence tomography angiography

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Journal of Innovative Optical Health Sciences 2022年第1期15卷 156-165页

作者： W.Gao B.Li S.Chen y.shi P.Lin O.O.Myakinin V.P.Zakharov School of Safety Engineering Ningbo University of Technology Ningbo P.R.China Department of Ophthalmology Ningbo First Hospital NingboP.R.China Department of Laser and Biotechnical Systems Samara University SamaraRussian Federation

The aim of this study is to detect whether the quantitative textural features of optical coherencetomography angiography (OCTA) images can be used to detect the eyes in the early stage ofdiabetic retinopathy (DR) from eyes with diabetes and no DR (NDR). Textural features includingfractal dimension, contrast, correlation, entropy, energy, and homogeneity were calculatedfrom the OCTA images. The Student's t-test was performed to identify the textural featuresthat can be able to detect DR in the early stage. The area under the receiver operating characteristic(AUROC) curves, sensitivity, and specicity were calculated between the study *** results indicated that the fractal dimension in ICP and SVP and the correlation in SVCshowed the statistical signicance between mild NPDR patients and NDR patients. The ROCanalysis results showed that the AUROC of the fractal dimension in ICP was 0.736 with 0.773sensitivity and 0.700 specicity. The cuto® point in ICP was 2.616. The OCTA-based fractaldimension was able to discriminate diabetic eyes with early retinopathy from healthy and NDRwith higher sensitivity and specicity. The OCTA-based correlation showed the power to differentiatethe mild NPDR eyes from the normal healthy and diabetic eyes. These results suggestthat texture-based features of OCTA have the potential to assist in the assessment of therapeuticinterventions to prevent early DR in diabetic subjects.

关键词： Optical coherence tomography angiography texture fractal dimension diabetic retinopathy

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Bullous Pemphigoid: Readability, Quality, and Treatments of Online Health Resources

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International Journal of Dermatology and Venereology 2022年第1期5卷 59-60页

作者： Terri shih Natalie Villa Jennifer L.Hsiao Vivian y.shi David Geffen School of Medicine University of California Los AngelesLos AngelesCA 90095USA Department of Dermatology Dartmouth-Hitchcock Medical CenterLebanonNH 03766USA Department of Dermatology University of Southern CaliforniaLos AngelesCA 90007USA Dermatology of Dermatology University of Arkansas for Medical SciencesLittle RockAR 72205USA

Dear Editor,Bullous pemphigoid(BP)is an autoimmune blistering disease that disproportionately affects the elderly,1 a population in which limited health literacy is a known barrier to health *** 2003 National Assessment of Adult Literacy survey found that among patients older than 65,59%had“basic”or“below basic”literacy,and only 3%were“proficient.”2 Despite increased utilization of the internet to seek health information,including among the elderly,3 the accessibility of online BP resources remain ***,we examine the readability and quality of online resources on BP.

关键词： autoimmune spite elderly

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Ultrasonic-based surface patterning and interfacial reaction of ZrO_(2)ceramics

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Journal of Materials Science & Technology 2023年第24期155卷 202-210页

作者： H.J. Dong Z.L. Li X.G.Song J.C. Feng S.J. Wei J.H. Fu y. shi State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Harbin 150001 China Shandong Provincial Key Lab of Special Welding Technology Harbin Institute of Technology at Weihai Weihai 264209 China

We demonstrate a process to achieve selective surface metallization of ZrO_(2)ceramics using ultrasound technology in atmospheric environments at 350℃,which bestows good weldability of ZrO_(2)to achieve rapid and reliable connections with other metals as well as ceramic *** challenge is that brazing or diffusion welding processes to accomplish metallurgical connections for ZrO_(2) typically require holding at elevated temperatures for minutes to hours,while the selective ultrasonic metallization process requires only a few seconds of processing without the application of covering films or solder *** this study,the selected Sn-2Ti alloy could effectively wet and spread on ZrO_(2)substrate under ultrasonication,and continuous interphase layers were rapidly formed in situ between ZrO_(2)and *** bonding strength for the ZrO_(2)/Sn-2Ti interface was well established with the highest shear strength of 37.1 MPa,and the fracture location occurred at the filler *** interfacial reaction layer thickened remarkably with the prolongation of sonication,accompanied by the partial crystallization of amorphous TiO and the formation of irregularly striped Ti_(11.31)Sn_(3)O_(10)nanocrystals.

关键词： Selective ultrasonic metallization Zirconia surface patterning Low temperature connection Sono-oxidation Interfacial reaction

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DEVELOPMENT AND APPLICATION OF ADAPTIVE MESH TECHNIQUE IN THREE DIMENSIONAL NUMERICAL SIMULATION OF WELDING PROCESS

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Acta Metallurgica Sinica(English Letters) 2000年第1期13卷 33-39页

作者： Q. y.shi A. L. Lu H. y.Zhao A.P. Wu (Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China)

The adaptive mesh mesh technique is developed and applied in three dimensional numerical simulation of welding process on the base of the commercial software. Special user subroutine is worked out to accom- plish this *** technique can make the dense mesh moving simultaneously with the heat source while the other area of the structure with much coarser mesh, greatly reducing the number of nodes and elements in the *** field,displacement and stress distributions during welding pro- cess me analyzed by FEM method with adaptive mesh and the analysis is also conducted with normal FEM method. The temperature field,displacement and stress distributions obtained with both methods are shown in contrast. The results show that the temperature fields and the displacement distributions of simulation on adaptive mesh correspond wery well with that of without adaptive mesh. Though the stress distributions have some difference,but the trends of the stress distribution are *** com- parison of the computing time of the two meshes indicates that the adaptive that the adaptive mesh can greatly reduce the calculation time when used for welding process.

关键词： adaptive mesh numerical simulation,temperature distribution,welding stress,welding displacement

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Mediating effect of self-efficacy in relationship between emotional intelligence and clinical communication competency of nurses

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International Journal of Nursing Sciences 2016年第2期3卷 162-168页

作者： B.Zhu C.-R.Chen Z.-y.shi H.-X.Liang B.Liu School of Nursing Henan UniversityKaifeng 475001China

Objective:This study investigates the emotional intelligence(EI),self-efficacy,and clinical communication ability of clinical nurses to explore the correlation among these three variables,and verify the mediating effect of self-efficacy on relationship between EI and communication ***:A total of 865 nurses were recruited and investigated using Wong and Law's Emotional Intelligence Scale,General Self-Efficacy Scale,and nurse clinical communication ***:The scores for EI and self-efficacy of nurses were 14.23±2.61 and 25.36±5.67,respectively,which were lower than the international norm(py of nurses was 4.14±*** clinical communication competency of nurses was positively correlated with EI and general ***,selfefficacy played an intermediary role between EI and clinical communication ***:Nursing administrators can improve the clinical communication ability of nurses by enhancing their self-efficacy and EI.

关键词： Clinical nurses Emotional intelligence Self-efficacy Clinical communication competency Mediating effect

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LSD1 ablation stimulates anti-tumor immunity and enables checkpoint blockade

LSD1 ablation stimulates anti-tumor immunity and enables che...

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中国生物化学与分子生物学会第十二届全国会员代表大会暨2018年全国学术会议

作者： Sheng WQ LeFleur MW Sharpe AH y.shi Boston Children's Hospital and Department of Cell Biology Harvard Medical School Department of Microbiology and Immunobiology Harvard Medical School

Chromatin regulators play a broad role in regulating gene expression,and when gone awry,can lead to *** we demonstrate that ablation of the histone demethylase LSD1 in cancer cells leads to dsRNA stress and activation of type 1 interferon,which stimulates anti-tumor T cell immunity and restrains tumor ***,LSD1 depletion enhances tumor immunogenicity and T cell infiltration in poorly immunogenic tumors,and elicits significant responses of checkpoint blockade-refractory mouse melanoma to anti-PD-1 *** study identifies LSD1 as a potent inhibitor of anti-tumor immunity

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Optimal Coordination of Transportable Power Sources and Repair Crews for Service Restoration of Distribution Networks Considering Uncertainty of Traffic Congestion

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 189-201页

作者： Zhao shi yan Xu Dunjian Xie shiwei Xie Amer M.y.M.Ghias Nanyang Technological University Singapore the School of Electrical Engineering and Automation Fuzhou UniversityFuzhou 350108China

This paper proposes a new method for service restoration of distribution network with the support of transportable power sources(TPSs)and repair crews(RCs).Firstly,a coupling model of distribution networks and vehicle routing of TPSs and RCs is proposed,where the TPSs serve as emergency power supply sources,and the RCs are used to repair the faulted *** the uncertainty of traffic congestion,the probability distribution of the travel time spent on each road is derived based on the Nesterov user equilibrium model,and a two-stage stochastic program is formulated to determine the optimal routings of TPSs and *** efficiently solve the proposed stochastic mixed-integer linear program(MILP),a two-phase scenario reduction method is then developed to scale down the problem size,and an adaptive progressive hedging algorithm is used for an efficient *** effectiveness of the proposed methods and algorithms has been illustrated in a modified IEEE 33-bus system.

关键词： Service restoration distribution network traffic uncertainty transportable power source repair crew stochastic program

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Identification of Watermelon mosaic virus infecting sesame in China

Identification of Watermelon mosaic virus infecting sesame i...

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中国植物病理学会2015年学术年会

作者： y.shi y.J.shi y.Z.WANG Z.y.WANG H.L.LI College of Plant Protection Henan Agricultural University

Seasame(Sesamum indicum) as one of the important economic crops in China is mainly distributed in Henan and Hubei province.A survey of viral diseases on sesame was carried out during the summer of 2014 in Henan province,*** the survey ten sesame fields in Zhengzhou and Zhumadian were investigated and in eight fileds mosaic,reduced leaf size,leaf deformation and leaf puckering were observed on sesame plants though the viral disease incidence was relatively low during our *** symptomatic samples were collected for virus *** RNA was extracted from symptomatic leaves and subjected to reverse transcription RT-PCR with degenerate primer pairs within the family Potyviridae,NIb2F(GTITGyGTIGAyGAyTTyAAyAA) and NIb3R(TCIACIACIGTIGAIGGyTGNCC)?(Zheng et al.2010).The expected 350-bp potyvirus-specific amplicon was observed in all symptomatic plants but not in the healthy *** amplicons were cloned and sequenced(GenBank Accession ***978924-KM978933).NCBI BLAST search showed that eight samples shared 95%9%nucleotide(nt) identity to Bean common mosaic virus strain peanut stripe isolate Laixi(GenBank Accession ***439722).The peanut stripe isolate of Bean common mosaic virus was previously reported as the pathogen causing mosaic disease in sesame(yan et al.2009).The other two samples shared the highest nt identity of 92%and 95%to Watermelon mosaic virus C04-106(WMV,GenBank Accession ***273469).WMV infection was previously reported in sesames in Korea(Chang et al.1980).During our investigation WMV infection in sesame which displayed symptoms of mosaic,dwarfing,reduced leaf size,small and reduced pods threatened sesame production in Henan *** two samples were further amplified by RT-PCR with WMV specific primer pair,wmv8249F(ACACACCAATCTTAGCGC) and wmv9798R(GACCAGTTTACCTAGTCT),which amplified a 1.5-kb product spanning 3’ half of the NIb gene to the 3’ UTR covering the full-length CP *** analyses indicated that CP g

关键词： Watermelon mosaic virus identification coat protein

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