关键词： Lime   Hydration   Material properties   Dewatering   Kinetics   Mortars   Hydrated lime   Strength   Time to dewater   Transfer sorptivity  

摘要： The CL90 mortar (i.e.,the nonhydraulic lime mortar) is dramatically more water retaining than any of the hydraulic mortars. This paper investigates the possible role of simple ionic solutions used as mix water on the water transport kinetics and mechanical properties of hydrated lime mortars. The results show that the addition of sulphate solutions as mix water does not only improve the transfer sorptivity and time to dewater, but also consistency and setting time of hydrated lime mortars. Compressive strength of hydrated lime mortars is significantly increased when potassium sulphate is used as mix water solution, and this is supported with microstructural analysis. The parameters studied in this paper form the main barriers to the use of hydrated lime mortars in construction practice;therefore, the use of hydrated lime mortars may be encouraged if the simple ionic solutions as mix water can improve the fresh and hardened properties of these mortars.

关键词： Forced unfolding   Intermediate states   Mechanical stability   Molecular dynamics   Mutations  

摘要： This article is the first to study the mechanical properties of the immunoglobulin-binding domain of protein L (referred to as protein L) and its mutants at the atomic level. In the structure of protein L, each amino acid residue (except for alanines and glycines) was replaced sequentially by alanine. Thus, 49 mutants of protein L were obtained. The proteins were stretched at their termini at constant velocity using molecular dynamics simulations in water, i.e. by forced unfolding. 19 out of 49 mutations resulted in a large decrease of mechanical protein stability. These amino acids were affecting either the secondary structure (11 mutations) or loop structures (8 mutations) of protein L. Analysis of mechanical unfolding of the generated protein that has the same topology as protein L but consists of only alanines and glycines allows us to suggest that the mechanical stability of proteins, and specifically protein L, is determined by interactions between certain amino acid residues, although the unfolding pathway depends on the protein topology. This insight can now be used to modulate the mechanical properties of proteins and their unfolding pathways in the desired direction for using them in various biochips, biosensors and biomaterials for medicine, industry, and household purposes.

关键词： oxygen atoms   calcium content   MEDICAL TREATMENT   molecular structure   Composites   chemical bond   Depolymerization   internal cohesion   Diffusion rate   Architectural engineering   Atoms   X systems   calcium silicate   Silicates   cement materials  

摘要： Calcium silicate composite (CaO)(x)(SiO2)(1-x) has significant applications in the bioactive materials in medical treatment and cementitious materials in construction engineering. In this study, to unravel the role of calcium atoms on the silicate composite, the molecular dynamics (MD) technique was used to simulate the structures, dynamics, and mechanical properties of (CaO)(x)(SiO2)(1-x) systems, with x varying from 0 to 0.6. The Feuston-Garofalini model was employed to describe the interatomic interactions in the systems. Q species, the connectivity factor, shows that the increase in calcium content in the silicate composite can lead to the depolymerization of the silicate network. Due to the high diffusion rate, the presence of Ca atoms also weakens the stability of the chemical bonds in the system. With the increasing calcium content, the molecular structure of the silicate skeleton is transformed from an integrity network to separated short chains, which significantly decreases the stiffness and cohesive force of the calcium silicate composites. On the other hand, the uniaxial tension response of the calcium silicate composites suggests that at the postfailure stage, Ca atoms associate with the nonbridging oxygen atoms and the reconstructed Ca-O connection slows down the irreversible damage of the composite, hereby enhancing the plasticity.

关键词： Amphiphilic polysaccharide   Emulsion   Rheo-optics   Interfaces  

摘要： Hexadecane-in-water emulsions were prepared by mechanical agitation in vane geometry using amphiphilic derivatives of dextran (nonionic bacterial polysaccharide) as stabilizers. Thanks to a laboratory-made experimental device coupling rheometry and back-scattered light analysis, we investigated the kinetics of droplet formation and the simultaneous variation of global shear stress. Oil volume fraction was varied between 10 and 50% and rotation speed between 40 and 100 rad s(-1). The viscosity of aqueous phase was controlled by addition of sodium alginate and thus exhibited non-Newtonian behavior. After forming a coarse emulsion, droplet rupture led to emulsions with volume-average droplet radius between 5 and 10 mu m provided that rotation speed and aqueous phase viscosity were high enough. Monitoring was consistent with droplet rupture occurring under shear forces such that capillary number remained approximately constant and close to its critical value. Although rotational speed and sodium alginate concentration had strong effect on emulsification kinetics, oil volume fraction had no significant effect. c 2014 Elsevier B. V. All rights reserved.

关键词： 液压元件   参数选择   动力匹配  

摘要： 液压行走系统在工程机械上应用越来越广泛,它以其平稳的传动性能和方便的操纵控制系统,在工程机械行走领域深受操作者的喜爱,但是液压行走元件的选择、计算是困扰工程机械设计人员的一个问题,为此,本文从工程机械行走系液压元件计算与动力匹配角度来探讨液压元件的选择方法。

关键词： 急性呼吸窘迫综合征   喷他佐辛   咪达唑仑   呼吸力学   应激反应  

摘要： 目的探讨喷他佐辛联合咪达唑仑对于急性呼吸窘迫综合征(ARDS)机械通气患者呼吸力学及血流动力学的影响。方法将100例ARDS患者随机平均分为2组,即咪达唑仑组(对照组,50例)和咪达唑仑+喷他佐辛组(治疗组,50例)。在治疗前和治疗24 h后对患者血流动力学指标(心率、平均动脉压、收缩压和舒张压),呼吸力学指标(呼吸频率、气道峰压和肺顺应性),血气分析指标(氧饱和度和氧合指数)以及氧化应激指标(血中超氧化物歧化酶和血中丙二醛)进行观察。结果治疗24 h后2组患者心率、平均动脉压、收缩压和舒张压均较治疗前下降(P均<0.05),但2组患者间各指标差异无统计学意义(P均>0.05)。在治疗24 h后,2组患者血氧饱和度(Sa O2)、氧合指数(Pa O2/Fi O2)、呼吸频率(RR)、吸气峰压(PIP)、肺动态顺应性(Crs)均较治疗前均有明显改善(P均<0.05);且治疗组较对照组改善更加显著(P均<0.05)。在治疗24 h后,2组患者血丙二醛(MDA)水平较治疗前明显升高,血超氧化物歧化酶(SOD)活性较治疗前明显下降(P均<0.05);与治疗组相比较,对照组患者血中MDA水平和SOD活性变化更显著(P<0.05)。在治疗过程中未出现与咪达唑仑和喷他佐辛相关的严重的不良反应。结论本研究发现咪达唑仑联合喷他佐辛进行镇静和镇痛,可以更加有效的改善ARDS患者氧合功能和肺顺应性以及抑制氧化应激反应。同时表明在ARDS患者有创机械通气过程中喷他佐辛和咪达唑仑有协同作用,且安全有效。

关键词： 紧急制动   岸桥集装箱起重机   制动冲击   动态响应  

摘要： 起重设备运行过程中的紧急制动,常常伴随巨大的冲击载荷,引起结构剧烈摇晃,在极端情况下甚至造成设备损坏。以某岸边集装箱起重机为例,建立其制动过程的运动学方程,以及结构在制动冲击下的瞬态动力学方程,讨论了不同制动策略对整机制动距离以及结构响应的影响,并实地测试其在不同制动策略下结构的动力学响应。研究表明,不同制动策略对制动距离和结构动力学响应有很大影响,可以通过调整制动策略,减小结构的水平振动位移响应。

关键词： 混合动力   工程机械   模糊   全功率   匹配  

摘要： 针对液压工程机械受剧烈变化的负载而导致的高油耗问题,提出了基于混合动力工程机械的两级模糊控制方法。首先根据泵的需求功率与发动机的负荷情况进行第一级模糊判断,给出电机应提供的助力力矩。其次,根据超级电容的能量状况,对泵和电动机助力力矩进行第二级模糊处理,调整助力力矩与泵的批量,从而实现发动机低油耗下的整机功率匹配。随后,在MATLAB与AMESIM中构建混合动力挖掘机这一特定模型,并将这一控制策略应用到所建模型,对比于传统的液压泵控系统,进行仿真,仿真结果表明,不仅能够有效的实现泵,发动机与超级电容之间的能量匹配,而且能够达到较好的整机作业效率与低油耗目标。应用到混合动力挖掘机的整机上进行试验,试验结果表明,具有较强的实用性与节油性。

关键词： 液压元件   参数选择   动力匹配  

摘要： 液压行走系统在工程机械上应用越来越广泛,它以其平稳的传动性能和方便的操纵控制系统,在工程机械行走领域深受操作者的喜爱,但是液压行走元件的选择、计算是困扰工程机械设计人员的一个问题,为此,本文从工程机械行走系统液压元件计算与动力匹配角度来探讨元件的选择方法。

关键词： 船舶动力机械系统   产品设计   状态监测与故障诊断   可监测性设计  

摘要： 船舶动力机械系统一旦出现故障直接威胁船舶安全,但是船舶服役后难以增加设备完善动力机械运行状态的监测。为此,提出了可监测性设计理论内涵,在常规船舶设计建造阶段考虑动力机械系统的可监测性,从而构建出可监测性设计理论在船舶动力机械系统设计中的工程应用框架。以远洋救助船动力机械系统为例,分析了可监测性设计理论在机械系统设计中的具体应用。实践证明,可监测性设计理论在船舶动力机械系统中的工程化实施增强了其可监测性,大大提高了自身状态监测和故障诊断能力水平,并且为船舶动力机械创新设计和机械系统的可再制造提供了保障和技术支撑。