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Chinese Journal of Aeronautics 2024年第3期37卷 391-403页

作者： Wei HAO andrews larbi Hongkang DONG Dongyun WANG Shenghu LI Zhejiang Provincial Key Laboratory of Urban Rail Transit Intelligent Operation and Maintenance Technology and Equipment Zhejiang Normal UniversityJinhua 321004China College of Engineering Zhejiang Normal UniversityJinhua 321004China Hangzhou Lilong Hydraulic Co. LtdHangzhou 311200China

The cylinder block/valve plate interface is one of the most critical frictional interfaces of the swashplate-type axial piston ***,the poor lubrication interface caused rapid wear and high friction loss in an elastohydrodynamic lubrication system,decreasing the pump *** resistant bronze coatings were fabricated on 38CrMoAl substrate by Physical Vapor Deposition(PVD)and Chemical Vapor Deposition(CVD),***-on-disc wear tests were performed to comparatively investigate the wear behaviors of the coatings and bulk ductile iron *** can be found that the PVD-bronze coating exhibited better wear resistance than the other two *** enhanced wear resistance was attributed to the unique composite microstructure and desired mechanical strength,which could resist to mechanical shear and spallation,decreasing friction *** appropriate hardness of(1.33±0.07)GPa could be beneficial for enhancing its wear *** PVD-bronze coating possessed a much lower and stable coefficient of friction(about 0.1)and wear rate(about 6000μm3.N-1.m-1)under the loading forces of about 100 N after 20 *** wear mechanism was the abrasive wear.

关键词： Aircraft hydraulic pump Bronze Coatings Wear resistance Mechanisms

基于表面形貌优化的轴向柱塞泵缸体/配流盘界面性能仿真与实验验证

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基于表面形貌优化的轴向柱塞泵缸体/配流盘界面性能仿真与实验验证

作者：安迪（larbi andrews）浙江师范大学

学位级别：硕士

斜盘式轴向柱塞泵在航空、航天,船舶及工程机械等领域具有广泛应用。因为它们能够在高压和高速下运行,同时保持高效率。缸体-配流盘摩擦副(配流副)是其最关键的摩擦副组件,而优异的承载能力、耐磨性能和密封性能是其在极端工况下长寿命... 详细信息

斜盘式轴向柱塞泵在航空、航天,船舶及工程机械等领域具有广泛应用。因为它们能够在高压和高速下运行,同时保持高效率。缸体-配流盘摩擦副(配流副)是其最关键的摩擦副组件,而优异的承载能力、耐磨性能和密封性能是其在极端工况下长寿命工作的保障。在泵低速运行时,摩擦副界面润滑不良导致配流副磨损加剧,甚至降低泵体的寿命。可见,配流副界面油膜不仅需要承受外部载荷,而且在界面上起润滑作用,可以保持缸体-配流盘摩擦副的润滑特性,保证泵的高效运行。油膜无法在高压下维持外部负载,摩擦热耗散的表面处理不良,导致界面磨损。针对以上问题,前期研究者们采用表面耐磨涂层技术提高配流副表面的耐磨性能,但是耐磨涂层织构化引入表面起伏,这样会破坏摩擦副表面原有结构,增加其表面局部的变形,对配流副的耐磨性能极其不利。为了解决上述问题,本论文首先通过理论建模和数值仿真对配流副组件进行动态特性分析,揭示了表面粗糙度参数对其泄漏流量的影响,及容积效率损失的主要原因,从而为配流副表面结构优化提供理论指导;其次,设计制备了不同微观结构的铜基耐磨涂层,对上述仿真模拟理论进行验证。具体研究内容如下:(1)为了优化配流副界面设计提高其耐磨性能,建立数值模型来预测配流盘上的微凹坑半径,更好地了解其界面磨损和弹性变形机理。还研究了不同工况下温度对油液运动粘度和表面变形的影响。使用三种不同材料的配流盘,即38Cr Mo Al基底的青铜涂层(P1)、38Cr Mo Al基底的PVD青铜涂层(P2)、和氮化体球铁(P3)。结果表明,增加表面粗糙度值会影响泄漏流量和摩擦界面上的压力积聚。由于材料微观结构、所需韧性和硬度之间的最佳相关性,配流盘的铅青铜PVD涂层显示出更好的摩擦学性能,可能具有耐磨性。(2)为了验证仿真结果,本论文设计制备了三种不同的配流副表面涂层材料(经过不同表面处理的配流盘、相同材料的缸体对磨件),即青铜涂层-38Cr Mo Al基体(P1)、PVD涂层-38Cr Mo Al基体(P2)、氮化处理后的球墨铸铁-38Cr Mo Al基体(P3),采用油液环境摩擦磨损实验研究了不同载荷下上述涂层材料的耐磨性能。结果表明,界面的表面粗糙度影响配流盘材料的摩擦系数和磨损率。因此,当配流盘表面被纹理化时,需要一个合适的Ra值～0.4μm以获得最佳的摩擦界面性能。此外,阀板的铅青铜PVD涂层(P2)表现出优异的摩擦学性能,其适当的相组成和微观结构被认为是更好的摩擦学性能的原因,这与仿真结果一致。分析了不同涂层组成、微观结构对轴向柱塞泵缸体/配流盘涂层耐磨性能的影响。结合涂层硬度的表征,揭示了表面涂层磨损失效机理。本文可为斜盘轴向柱塞泵缸体/配流盘摩擦副的优化设计提供指导。

关键词：轴向柱塞泵缸体-配流盘界面动力学仿真模拟弹性变形耐磨性能失效机理

Molecular regulation of calcium-sensing receptor(CaSR)-mediated signaling

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Chronic Diseases and Translational Medicine 2024年第3期10卷 167-194页

作者： Li Tian Corey andrews Qiuyun Yan Jenny J.Yang Department of Chemistry Center for Diagnostics and TherapeuticsAdvanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA

Calcium-sensing receptor(CaSR),a family C G-protein-coupled receptor,plays a crucial role in regulating calcium homeostasis by sensing small concentration changes of extracellular Ca^(2+),Mg^(2+),amino acids(e.g.,L-Trp and L-Phe),small peptides,anions(e.g.,HCO_(3)^(-)and PO_(4)^(3-)),and ***-mediated intracellular Ca^(2+)signaling regulates a diverse set of cellular processes including gene transcription,cell proliferation,differentiation,apoptosis,muscle contraction,and neuronal *** of CaSR with mutations results in diseases such as autosomal dominant hypocalcemia,familial hypocalciuric hypercalcemia,and neonatal severe *** also influences calciotropic disorders,such as osteoporosis,and noncalciotropic disorders,such as cancer,Alzheimer's disease,and pulmonary arterial *** study first reviews recent advances in biochemical and structural determination of the framework of CaSR and its interaction sites with natural ligands,as well as exogenous positive allosteric modulators and negative allosteric *** establishment of the first CaSR protein-protein interactome network revealed 94 novel players involved in protein processing in endoplasmic reticulum,trafficking,cell surface expression,endocytosis,degradation,and signaling *** roles of these proteins in Ca^(2+)-dependent cellular physiological processes and in CaSR-dependent cellular signaling provide new insights into the molecular basis of diseases caused by CaSR mutations and dysregulated CaSR activity caused by its protein interactors and facilitate the design of therapeutic agents that target CaSR and other family C G-protein-coupled receptors.

关键词： calcium signaling calcium-sensing receptor G-protein-coupled receptors structure trafficking

Considerations for the use of porcine organ donation models in preclinical organ donor intervention research

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Animal Models and Experimental Medicine 2024年第3期7卷 283-296页

作者： Frazer I.Heinis Shaheed Merani Nicholas W.Markin Kim F.Duncan Michael J.Moulton Lance Fristoe William E.Thorell Raechel A.Sherrick Tami R.Wells Matthew T.andrews Marian Urban School of Natural Resources Institute of Agriculture and Natural ResourcesUniversity of Nebraska-LincolnLincolnNebraskaUSA Division of Transplantation and Vascular Surgery Department of SurgeryUniversity of Nebraska Medical CenterOmahaNebraskaUSA Department of Anesthesiology University of Nebraska Medical CenterOmahaNebraskaUSA Division of Cardiothoracic Surgery Department of SurgeryUniversity of Nebraska Medical CenterOmahaNebraskaUSA Clinical Perfusion Nebraska Medicine-Nebraska Medical CenterOmahaNebraskaUSA Department of Neurosurgery University of Nebraska Medical CenterOmahaNebraskaUSA Nutrition and Health Sciences College of Education and Human SciencesUniversity of Nebraska-LincolnLincolnNebraskaUSA Department of Comparative Medicine University of Nebraska Medical CenterOmahaNebraskaUSA

Use of animal models in preclinical transplant research is essential to the optimization of human allografts for clinical *** models of organ donation and preservation help to advance and improve technical elements of solid organ recovery and facilitate research of ischemia-reperfusion injury,organ preservation strategies,and future donor-based *** considerations include cost,public opinion regarding the conduct of animal research,translational value,and relevance of the animal model for clinical *** present an overview of two porcine models of organ donation:donation following brain death(DBD)and donation following circulatory death(DCD).The cardiovascular anatomy and physiology of pigs closely resembles those of humans,making this species the most appropriate for pre-clinical *** are also considered a potential source of organs for human heart and kidney *** is imperative to minimize animal loss during procedures that are surgically *** present our experience with these models and describe in detail the use cases,procedural approach,challenges,alternatives,and limitations of each model.

关键词： animal model brain death circulatory death organ transplantation

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混动飞机飞向蓝天

科技纵览 2024年第2期 30-36,4页

作者： Amy Jankovsky Christine andrews Bill Rogers 不详

NASA、通用电气航空公司和波音公司正在合作开发一款混合动力客机。商业航空联结了现代世界。国际民用航空组织(ICAO)的数据表明,在全球新冠疫情之前,每天平均有1200万人乘坐约10万次商业航班。这些数字现在已经大幅回升:预计2023年行... 详细信息

NASA、通用电气航空公司和波音公司正在合作开发一款混合动力客机。商业航空联结了现代世界。国际民用航空组织(ICAO)的数据表明,在全球新冠疫情之前,每天平均有1200万人乘坐约10万次商业航班。这些数字现在已经大幅回升:预计2023年行业收入将达到8030亿美元,比2022年增长9.7%,接近2019年疫情前的峰值。

关键词：商业航空混合动力通用电气合作开发数据表波音公司航空公司疫情

Kinetics of hydrogen peroxide quenching following UV/H_(2)O_(2)advanced oxidation by thiosulfate,bisulfite,and chlorine in drinking water treatment

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Frontiers of Environmental Science & Engineering 2023年第12期17卷 59-69页

作者： Tianyi Chen Lizbeth Taylor-Edmonds Susan andrews Ron Hofmann Department of Civil and Mineral Engineering University of TorontoTorontoOntario M5S 1A4Canada

Residual H_(2)O_(2)from UV/H_(2)O_(2)treatment can be quenched by thiosulfate,bisulfite,and chlorine,but the kinetics of these reactions have not been reported under the full range of practical *** this study,the rates of H_(2)O_(2)quenching by these compounds were compared in different water matrices,temperatures,pH,and when using different forms of bisulfite and *** general,it was confirmed that thiosulfate would be too slow to serve as a quenching agent in most practical *** pH 7-8.5,chlorine tends to quench H_(2)O_(2)more than 20 times faster than bisulfite in the various conditions *** important observation was that in lightly-buffered water(e.g.,alkalinity of 20 mg/L as CaCO_(3)),the form of chlorine can have a large impact on quenching rate,with gaseous chlorine slowing the reaction due to its lowering of the pH,and hypochlorite having the opposite *** impacts will become less significant when water buffer capacity(i.e.,alkalinity)increases(e.g.,to 80 mg/L as CaCO_(3)).In addition,water temperature should be considered as the time required to quench H_(2)O_(2)by chlorine at 4℃is up to 3 times longer than at 20℃.

关键词： UV/H_(2)O_(2) H_(2)O_(2) quenching Chlorine type Water alkalinity Temperature

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遍布火山的卫星

环球科学 2024年第3期 12-14页

作者：罗宾·乔治·安德鲁斯巢栩嘉(译) 不详

关于木卫一(lo),科学家可以肯定两件事情。一是,木星的这颗卫星是目前宇宙中已知的火山最多的天体。它的地表布满了大量火山口,这些火山口不断地喷出熔岩,就像一个在烤箱里烘烤过的奶酪披萨.

关键词：火山口木星木卫一宇宙天体熔岩

Resting-state functional connectivity in lifelong musicians

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Psychoradiology 2023年第1期3卷 154-161页

作者： Cyrus Eierud Andrew Michael David Banks Edna andrews Linguistics Program Duke UniversityDurhamNC 27708USA Duke Institute for Brain Sciences Duke UniversityDurhamNC 27708USA Department of Statistical Science Duke UniversityDurhamNC 27708USA Center for Cognitive Neuroscience Duke UniversityDurhamNC 27708USA

Background:It has been postulated that musicianship can lead to enhanced brain and cognitive reserve,but the neural mechanisms of this effect have been poorly *** professional musicianship in conjunction with novel brain imaging techniques offers a unique opportunity to examine brain network differences between musicians and matched ***:In this study we aim to investigate how resting-state functional networks(FNs)manifest in lifelong active *** will evaluate the FNs of lifelong musicians and matched healthy controls using resting-state functional magnetic resonance ***:We derive FNs using the data-driven independent component analysis approach and analyze the functional network con-nectivity(FNC)between the default mode(DMN),sensory-motor(SMN),visual(VSN),and auditory(AUN)*** examine whether the linear regressions between FNC and age are different between the musicians and the control ***:The age trajectory of average FNC across all six pairs of FNs shows significant differences between musicians and *** show an increase in average FNC with age while controls show a decrease(P=0.013).When we evaluated each pair of FN,we note that in musicians FNC values increased with age in DMN–AUN,DMN–VSN,and SMN–VSN and in controls FNC values decreased with age in DMN–AUN,DMN–SMN,AUN–SMN,and SMN–***:This result provides early evidence that lifelong musicianship may contribute to enhanced brain and cognitive *** of this study are preliminary and need to be replicated with a larger number of participants.

关键词： resting-state fMRI lifelong musicianship default mode network sensory-motor network functional network connectivity cognitive reserve

Underground mine stream crossing assessment:A multi-disciplinary approach

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International Journal of Mining Science and Technology 2021年第1期31卷 59-65页

作者： Kevin andrews Steve Keim Marshall Miller&Associates BluefieldVA 24605USA

Underground mine designs typically try to avoid extraction beneath streams and rivers of any significant size,especially when the overburden rock thickness between the stream bed and the mine is *** issues with mining beneath streams include excessive groundwater inflow to the mine,weak ground(roof,floor,and pillar)conditions,horizontal stress effects,as well as stream loss and other potential adverse environmental ***,there are times when crossing beneath a stream or river is necessary to move into a new area of mineral reserve without creating additional mine access points from the ground ***,stream crossings are completed without thorough assessment,potentially resulting in increased costs,decreased safety,and,in some cases,failure to advance the *** of the most favorable location(s)to cross the stream must account for numerous factors and the associated assessment often requires a multi-disciplinary *** crossing investigations often require geological,hydrogeological,geotechnical,and geophysical *** of stream crossing investigations include desktop evaluation of maps and aerial photography,stream bed observations,drilling,detailed rock core logging,downhole geophysical surveying,hydraulic conductivity testing(packer testing),geotechnical laboratory testing,assessment,and *** deliverables from a stream crossing assessment typically include geological,geotechnical,and hydrogeological characterization of potential stream crossing locations,classification of favorable and unfavorable crossing locations,recommendations for entry design and pillar sizing,and recommendations for if,and how,to conduct pre-grouting *** of technical aspects of data collection and assessment are provided based on decades of industry experience conducting stream crossing assessments in various underground mining scenarios.

关键词： Underground mining Geotechnical Stream-crossing Hydrogeology Characterization

Advances in orthodontic clear aligner materials

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Bioactive Materials 2023年第4期22卷 384-403页

作者： Yashodhan M.Bichu Abdulraheem Alwafi Xiaomo Liu James andrews Bjorn Ludwig Aditi Y.Bichu Bingshuang Zou Private Practice Abu DhabiUnited Arab Emirates Department of Oral Health Science Faculty of DentistryUniversity of British ColumbiaVancouverCanada Faculty of Dentistry Department of Dental Public HealthKing Abdulaziz UniversityJeddahSaudi Arabia Department of Orthodontics Peking University School and Hospital of StomatologyBeijingChina Private Practice PerthAustralia Department of Orthodontics University of HomburgSaarGermany

Rapid technological improvements in biomaterials,computer-aided design(CAD)and manufacturing(CAM)have endorsed clear aligner therapy(CAT)as a mainstay of orthodontic treatment,and the materials employed for aligner fabrication play an all-important role in determining the clinical performance of clear *** narrative review has attempted to comprehensively encompass the entire gamut of materials currently used for the fabrication of clear aligners and elucidate their characteristics that are crucial in determining their performance in an oral *** developments and current protocols in aligner fabrication,features of contemporary bioactive materials,and emerging trends related to CAT are *** in aligner material chemistry and engineering possess the potential to bring about radical transformations in the therapeutic applications of CAT;in the absence of which,clear aligners would continue to underperform clinically,due to their inherent biomechanical ***,while innovations in aligner materials such as shape memory polymers,direct three-dimensional(3D)printed clear aligners and bioactive materials combined with clear aligner materials are essential to further advance the applications of CAT;increased awareness of environmental responsibilities among aligner manufacturers,aligner prescribing clinicians and aligner users is essential for better alignment of our climate change goals towards a sustainable planet.

关键词： Clear aligners Bioactive materials Shape memory polymers Direct 3D printing Environment Review