关键词： antiperovskite   formation energy   mechanical properties   phonon   p‐   type semiconductors   structural properties   thermoelectric properties  

摘要： We present a comparative study on the structural, electronic, elastic, and thermoelectric properties of the cubic inverse-perovskites A(3)OX (where A = Li, Na, K and X = Cl, Br, I) by density functional theory (DFT). The cohesive, formation, and elastic properties analysis indicates that all studied materials are chemically, thermodynamically, and mechanically stable. Electronic properties reveal that all the inverse A(3)OX perovskite are direct bandgap semiconductors except Li3OCl and Li3OBr with ionic nature which is confirmed by electron localization function (ELF) analysis. We have also calculated Debye temperature (Theta(D)) and Gruneisen parameter (gamma) to determine the lattice thermal conductivity for all the A(3)OX materials. Furthermore, thermoelectric (TE) properties are explored by calculating the Seebeck coefficient (S), electronic thermal conductivity, power factor (PF), electrical conductivity (sigma/tau), lattice thermal conductivity, and ZT value. Our investigated A(3)OX inverse-perovskites provide a fertile base that can improve the overall TE performance for TE applications and green energy production.

标准号: GB/T 39832-2021

摘要： 本标准给出了用于农业、园艺和区域维护(景观美化)的物料动力收集装置的设计和结构的安全要求和方法。本标准适用于园艺用悬挂式、半悬挂式或牵引式机械。本标准规定了物料收集系统按预定使用时排除和减少机械危险的方法。本标准不涉及环境危险，道路安全，电磁兼容性，动力输出轴(PTO)，动力输出传动轴防护装置或控制要求。

关键词： Ligands  

摘要： The reduction of An(vi) (An = U, Np, and Pu) to An(iv) significantly decreases its solubility and mobility. This reaction can be hindered by complexation with inorganic (e.g., carbonate) or organic ligands. Ethylenediaminetetraacetic acid (EDTA) is one such organic ligand that forms stable complexes with actinides. Therefore, it may enhance the mobility of actinides. However, the redox kinetics and mechanisms of actinyl (An(v/vi)O-2(+/2+))-EDTA are not well characterized yet and are thus studied here using quantum-mechanical calculations. The principle is to approach the actinyl-EDTA and Fe2+ (reductant) in small incremental steps and calculate the system energy at each distance. The overall reaction is then delineated into sub-processes (encounter frequency in bulk solution, formation of outer-sphere complex, transition from outer- to inner-sphere complex, and electron transfer), and reaction rates are determined for each sub-process. The formation of outer-sphere complexes occurs rapidly in microseconds to seconds over a wide range of actinyl concentrations (pM to mu M);in contrast, the transition to the inner-sphere complex is relatively slow (milliseconds to a few seconds). Immediate electron transfer to form the pentavalent actinide is observed along the reaction path for Np(vi) and Pu(vi), but not for U(vi). Surprisingly, in acidic conditions, one of the carboxylic groups gets protonated in EDTA of [UO2(edta)](2-) rather than one of the amino groups. This process-based series of calculations can be applied to any redox reaction and allows the prediction of changes to the rate law and rate-limiting step in a more fundamental way for different environments.

关键词： DFT   Ozanimod   TD-DFT   Non-covalent interactions   Molecular docking  

摘要： Ozanimod is a newly formulated drug used to manage relapsing multiple sclerosis. Here, we use computational chemistry tools to study the structure and various physio-chemical properties of the molecule. We applied the dispersion corrected omega B97XD functional with DGDZVP as a basis set and DEF2SV as a fitting set to determine the geometry of the molecule. Potential energy scan predicts that the most stable conformer is stable by 8.15 kcal/mol with respect to the eclipsed conformation. Time dependent density functional theory (TD-DFT) with CAM-B3LYP and the same basis sets were used to study the electronic spectra in methanol solvent. Non covalent interactions, average local ionization energy, and energy descriptors helped in predicting the reactivity and stability of the molecule. The compound also had excellent non-linear optical properties when compared to the standard material urea. Screening for biological activity followed by molecular docking studies suggested that ozanimod interacts with three proteins responsible for autoimmune disorders. (C) 2020 Elsevier B.V. All rights reserved.

关键词： GaAs nanowires   Nanomechanics   In-situ TEM mechanical Tests   Tensile deformation   Molecular dynamics simulation  

摘要： Nanowire-based devices have been widely applied in optoelectronics, sensors, generators and spectroscopy. These nanowires are typically subjected to mechanical conditions during manufacture or operation. Thus, a compressive understanding of nanowire mechanical properties is increasingly required. However, only limited results have been reported owing to the challenges inherent in nanomechanical testing, particularly for quantitative tensile deformation. Herein, taper-free zinc blende GaAs nanowires with a 120 nm diameter are grown along the [111]B direction using metalorganic vapor phase epitaxy. The mechanical properties and fracture mechanisms of these single-phase GaAs nanowires are explored by in-situ uniaxial tensile deformation inside a transmission electron microscope, followed by molecular dynamics simulations. Under tensile stress, GaAs nanowires deform overally elastically until sudden brittle fracture at 3.79% strain. The fracture strength and elastic modulus are experimentally determined as 4.0 and 109.5 GPa, respectively, which are much smaller than other reported results based on compression. The tensile deformation and fracture mechanisms are further explored using molecular dynamics simulations, and the effects of different crystal structures on the GaAs nanowire mechanical behavior are discussed. These results assess the mechanical behavior of single GaAs nanowires and present critical insights into the reliable design of engineering nanodevices.

关键词： 风电基础   ANSYS   Matlab/Simulink   黏性阻尼系数   刚度  

摘要： 采用Matlab/Simulink软件分别对机械振动激励和地震激励作用下的风电基础进行了动力仿真分析.基于有限元软件ANSYS对风电基础的动力学参数进行了计算.采用时程分析法对风电基础在输入机械振动激励和地震激励时的位移、速度和加速度时程曲线进行了仿真.研究了黏性阻尼系数和刚度对风电基础动力响应的影响.研究结果表明,风电基础的最终响应状态是由所输入的激励状态所决定,黏性阻尼系数的大小对风电基础的动力响应无明显影响,而刚度大小对其动力响应影响明显,在一定范围内,随着刚度的增加,风电基础的位移、速度时程曲线波动越大.

关键词： 专业学位研究生   专业课程   教学改革   实践能力  

摘要： 专业课程是专业学位硕士研究生培养重要一环,为了更好激发研究生创新能力和提高实践动手能力,本文对“动力机械测试技术”课程的教学内容、教学方法和教学手段等进行探索,以此提高专业学位硕士研究生的培养质量,同时为高校专业学位研究生课程综合改革提供借鉴。

关键词： 材料成型及控制工程   能源与动力工程   机械电子工程   卓越工程师教育培养计划   国家特色专业   机械设计制造及其自动化   三峡大学   核工程与核技术  

摘要： 2014年1月原机械与材料学院更名为机械与动力学院,学院现设有机械设计制造及其自动化、机械电子工程、材料成型及控制工程、工业工程、能源与动力工程、核工程与核技术六个本科专业,其中机械设计制造及其自动化为国家特色专业、第二批卓越工程师教育培养计划专业和省本科品牌专业,材料成型及控制工程为第三批卓越工程师教育培养计划专业。

关键词： 电力投资   产业创新   重大科技专项   上海交通大学   核科学技术   核电事业   工程学院   核电技术  

摘要： 经过多年发展,我国核科学技术创新及核能产业发展,近期又取得了令人欣喜的新成绩。2020年9月28日,中国国家电力投资集团宣布,中国具有完全自主知识产权的三代核电技术“国和一号”完成研发。“国和一号”,是中国十六个重大科技专项之一,代表着当今世界三代核电技术的先进水平,是中核电技术研发和产业创新的最新成果。

关键词： 呼气末正压通气方式机械通气   急性左心衰竭   心源性休克   血流动力学   血气状况   临床疗效   不良反应  

摘要： 目的探讨呼气末正压通气(PEEP)方式机械通气治疗急性左心衰竭并心源性休克的临床效果及对血流动力学和血气状况的影响。方法选取2018年5月—2020年8月安徽皖北煤电集团总医院收治的急性左心衰竭并心源性休克患者80例,按照随机数表法将其分为对照组和观察组,每组各40例。对照组给予常规基础治疗,观察组给予PEEP方式机械通气治疗。于治疗1周后对两组临床疗效及治疗前后血流动力学[心率(HR)、收缩压(SBP)、多巴胺]和血气状况[动脉血二氧化碳分压(PaCO2)、动脉血氧分压(PaO2)、PaO2/吸氧浓度(FiO2)及pH值]进行比较分析。结果观察组总有效率高于对照组,差异有统计学意义(P<0.05)。观察组治疗后HR、SBP水平高于对照组,多巴胺水平低于对照组,差异均有统计学意义(均P<0.05)。观察组治疗后PaCO2水平低于对照组,PaO2、PaO2/FiO2水平及pH值高于对照组,差异均有统计学意义(均P<0.05)。结论PEEP方式机械通气治疗急性左心衰竭并心源性休克临床效果显著,可促进患者血流动力学及血气状况改善,缓解临床症状,值得临床推广应用。