关键词： Metals and alloys   Nanoparticles   Crystal structure   Diffusion   Interfaces   Recrystallization  

摘要： The study compares the precipitation kinetics of the L1(2)-structured phase, microstructure, and mechanical properties in Al-Mg-Zr and Al-Mg-Sc-Zr alloys with a close atomic concentration of dispersoid-forming elements. Continuous and discontinuous precipitation mechanisms leading to spherical nanoscale and fan-shaped precipitates are revealed in both alloys. Scandium raises the precipitation kinetics of L1(2)-structured dispersoids owing to its high diffusivity in Al. The low effect of two-stage annealing on precipitation and mechanical properties is observed in the Sc-bearing alloy compared to the Sc-free one. Due to heat treatment optimization, the Sc-free alloy exhibits higher yield strength as compared with the alloy containing both Sc and Zr. The Sc-free alloy requires a long-term two-step heat treatment to provide increased precipitates number density and high-strength values. (C) 2020 Elsevier B.V. All rights reserved.

关键词： 液力变矩器   动力匹配   仿真  

摘要： 对配有液力变矩器的工程机械传动系统匹配方法进行了对比研究,分析了传统匹配方法的优劣势,并结合实际工况和整车等效万有特性,提出了一种新的液力机械动力总成匹配方法。应用该方法研究了液力变矩器能容和变矩比对整车性能的影响,并对一款实际生产的叉车进行分析,完成动力总成系统的优化。该方法对液力机械动力总成匹配具有重要的参考价值。

关键词： 液压   应急动力   工程机械   设计研究  

摘要： 通过对工程机械液压应急动力设计的研究,从元件选型、参数设计和系统匹配三个维度进行详细阐述,明确了液压应急动力设计的关键因素。同时,文章结合具体应用案例,针对调试过程中存在的问题进行分析和对策,进一步验证了液压应急动力设计合理选型和正确匹配的重要性,从而提高设计的可行性。

关键词： Cobalt catalyst   Proton reduction   Water reduction   FOWA   Hydrogen evolution  

摘要： This paper presents the synthesis and characterization of [Co(Fc-tpy)(2)](PF6)(2) complex which acts as an active electrocatalyst for H-2 evolution in both organic and aqueous media (Fc-tpy = 4'-ferrocenyl-2,2':6',2 ''-terpyridine). It exhibits the electrocatalytic H-2 evolution in the presence of acetic acid as the proton source in (95:5 v/v) DMF/H2O medium with approximate to 90% of faradic efficiency in the overpotential range of 655 mV to 955 mV. The complex exhibits an i(c)/i(p) value of 65 having TOF of 825 s(-1), whereas under similar condition it is 366 s(-1) in case of [Co(tpy)(2)](2+) complex. In the presence of Fc-group in the terpyridine moiety of [Co(Fc-tpy)(2)](2+) the overpotential decreases up to 200 mV as compared to the [Co(tpy)(2)](2+) complex due to the electron donating effect of ferrocene. The mechanistic and the kinetics studies have been depicted in the presence of cobaltocene and found that interaction of Co(II)-H-delta center dot center dot center dot H delta+ is the rate-determining step in the catalytic process. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： 多发伤   机械通气   右美托咪定   咪达唑仑   白介素-6   肿瘤坏死因子-α  

摘要： 目的研究右美托咪定对机械通气患者血流动力学及血清IL-6、TNF-α水平的影响。方法选取2019年1月至2020年1月广西医科大学附属武鸣医院收治的多发伤需机械通气的患者60例,采用随机数表法分为观察组和对照组,各30例。对照组患者采用咪达唑仑治疗,观察组患者采用右美托咪定治疗。比较两组患者镇静效果,T_0、T_1、T_2的血流动力学指标及血清IL-6、TNF-α水平。结果观察组患者早期目标镇静达成时间、停药后完全清醒时间和机械通气拔管时间均显著短于对照组;从T_0至T_2时两组患者HR、SBP、DBP均逐渐降低,T_1和T_2时观察组患者HR、SBP、DBP均显著高于对照组(P <0.05);从T_0至T_2时两组患者血清IL-6及观察组患者的TNF-α水平均逐渐降低,且T_1和T_2时观察组均显著低于对照组(P <0.05)。结论右美托咪定用于多发伤机械通气临床治疗中可改善患者临床效果,患者血流动力学更平稳,同时降低炎症因子水平,减轻炎症反应。

摘要： Mechanical signals regulate functions of mechanosensitive proteins by inducing structural changes that are determinant for force-dependent interactions. Talin is a focal adhesion protein that is known to extend under mechanical load, and it has been shown to unfold via intermediate states. Here, we compared different nonequilibrium molecular dynamics (MD) simulations to study unfolding of the talin rod. We combined boxed MD (BXD), steered MD, and umbrella sampling (US) techniques and provide free energy profiles for unfolding of talin rod subdomains. We conducted BXD, steered MD, and US simulations at different detail levels and demonstrate how these different techniques can be used to study protein unfolding under tension. Unfolding free energy profiles determined by BXD suggest that the intermediate states in talin rod subdomains are stabilized by force during unfolding, and US confirmed these results.

关键词： 俯卧位   机械通气   重症   吸入性肺炎  

摘要： 目的:通过比较仰卧位机械通气(supine position ventilation,SPV)和俯卧位机械通气(prone position ventilation,PPV)对重症吸入性肺炎患者呼吸功能和血流动力学的影响,进一步探究俯卧位机械通气对重症吸入性肺炎患者的疗效,为合理的临床诊疗提供更多理论依据。方法:选取2018年1月-2019年12月就诊笔者医院重症医学科的174例重症吸入性肺炎患者作为研究对象,均实施机械通气治疗,按照随机数字表法分为SPV组(n=91,仰卧位)与PPV组(n=83,俯卧位),对两组治疗效果进行对比。结果:治疗前两组FiO2、PEEP、PaO2、PaCO2、SpO2及OI比较差异无统计学意义(P>0.05),治疗后第1、3天PPV组FiO2、PEEP均高于SPV组,而PaO2、SpO2、OI均低于SPV组,差异均有统计学意义(P<0.05),两组治疗后第5、7天FiO2、PEEP、PaO2、SpO2、OI比较差异均无统计学意义(P>0.05),治疗后两组PaCO2比较差异均无统计学意义(P>0.05)。治疗前两组HR、MAP及CVP比较差异无统计学意义(P>0.05),治疗后第1天PPV组HR高于SPV组,差异有统计学意义(P<0.05),治疗后第3、5、7天两组HR比较差异无统计学意义(P>0.05),治疗后两组MAP、CVP比较差异均无统计学意义(P>0.05)。结论:俯卧位机械通气能够迅速改善重症吸入性肺炎的呼吸功能且对血流动力学无明显影响,但远期疗效无明显优势。

关键词： Si/Ge   Layer effect   Fracture   Size effect   Crystalline  

摘要： In this study, the mechanical properties of Si/Ge multilayer nanofilms were simulated by molecular dynamics (MD) in tensile and compression tests. The tensile test results show the fracture mechanism of the Si/Ge multilayer nanofilm. The phase transition process of the Si/Ge multilayer films is revealed by the strain energy distribution and structure distribution during the tensile test. The mechanical response of Si/Ge multilayer films is caused by size effects and critical film thickness. Furthermore, the effects of the number of layers and temperature on deformation and dynamic mechanical response are also studied.

关键词： statistical dynamics of systems   reliability   parametric oscillations   stability  

摘要： In this paper, we consider the computational prediction problem of the reliability of mechanical systems that are in operation under irregular loads, which is relevant for modern mechanical engineering. The calculation problems include determining the functioning reliability of such systems as the probability that the parameters (linear and angular displacements, accelerations of the mass of a spring, deformations of an elastic element, etc.) do not exceed their quality. We propose a new method for choosing the optimal parameters of vibration protection systems for mobile machines and a method for calculating the critical velocity of their movement on roads with random irregularities.

关键词： Dispersion   Carbon nanotubes   Surfactants   Molecular dynamics   Mechanical properties  

摘要： Identification of the suitable surfactant that effectively disperses carbon nanotubes (CNTs) and also ensuring the compatibility of surfactant with constituents/hydrates of cementitious composite is very important to develop efficient CNT incorporated cementitious composite. In view of this, molecular dynamics (MD) simulations are carried out to investigate the dispersibility of CNTs by surfactants and their compatibility with the major hydrate, i.e., calcium-silicate-hydrate (CSH). The results obtained from the MD simulations are validated with experimental investigations. Further, detailed investigations are carried out to determine the stress-strain behaviour, bulk and shear modulus, bond properties, etc. of CNT incorporated composite. The incorporation of CNT into CSH has significantly improved its strength, and elastic- and shear- modulus. This study also demonstrates that incorporation of CNT into CSH system changes the composite from brittle to a ductile one, and the degree of ductility imparted can be quantitatively evaluated. The findings of this study will help in designing the cementitious composite with desired properties. (C) 2020 Elsevier Ltd. All rights reserved.