关键词： Surfactant adsorption   APPARENT VISCOSITY   agglomeration   solid-state phase transformations   kinetic simulation   additive effect   Disperse systems   nonuniformity   viscosity curve  

摘要： A computer model has been developed to refine the notions of the kinetics of structural transformations in surfactant-modified disperse systems, the mechanism of the influence of adsorption layers on viscosity, conditions of aggregation, and evolution of nonuniformities in microstructures. Classical concepts of the structure-related mechanical barrier providing disperse systems with stability to aggregation, as well as the criterion of adsorption-layer breakdown upon interparticle collisions under dynamic conditions, have been used. It has been shown that adsorption-layer breakdown under dynamic conditions may lead to the appearance of an extreme in the viscosity curve of a disperse system. The combined effect of additives of surfactants with different molecular masses successively added to the systems has been studied via taking into account the influence of surfactant adsorption layers on the dynamics of contact interactions. The simulation results make it possible to optimize the regulation of structure-related rheological properties of dispersions so as to decrease their apparent viscosity with a simultaneous increase in the uniformity of the structure.

关键词： relativity   quantum mechanics   centre of mass   entanglement  

摘要： Although special relativity and quantum mechanics revolutionised physics in the early 20th century, the consequences of combining these two theories are still being explored a hundred years later, usually using the formidable theoretical machinery of quantum field theory. However, a formalism accessible to undergraduates has been recently developed which shows how the centre of mass and internal dynamics of classical and quantum systems is relativistically coupled with interesting consequences. Here we explore some of the implications of this coupling, first classically, where we find that the dynamics of the system is time dilated when moving relative to another inertial frame. We then apply the dynamics to a quantum 2-level atom bound in a one-dimensional infinite potential well, and show that the coupling produces collapses and revivals in quantum interference. This example provides an illustration of how the combination of special relativity and quantum mechanics can be studied in situations familiar to most undergraduates.

关键词： 机械功   热能   动力工程   应用   优化  

摘要： 所谓机械功可以称之为功,简单的说是物体在力的方向移动了一定的距离,并且前提是作用于该物体的合力要控制在不是零的情况下,只有这样才能随着合外力及其移动距离的增加而发生变化。而机械功在热能与动力工程使用的次数较为频繁,基本都会包含到力的范围,正是因为它可以发挥出自己的价值,所以才能够促使工程成本及其工作水平得到进一步的完善。

关键词： Double network hydrogels   Strong and stretchable hydrogels   Swelling kinetics   Tensile strength  

摘要： Strong and stretchable double network (DN) hydrogels are reported here which are consisting of first network of PVA-borax double strand and crosslinked P(AM-co-HEMA) as the second network. The first network is formed due to PVA-borax complexation in which the second network of AM and HEMA was embedded by in-situ polymerization. These DN hydrogels are having high degree of equilibrium swelling and mechanical properties. The swelling behavior of the hydrogels increased with AM content and decreased with HEMA content because of more hydrophilic nature of AM unit than HEMA unit in DN hydrogels. The tensile strengths of such hydrogels were observed to be 363.0 kPa, 183.4 kPa and 36.3 kPa respectively for the 20 wt%, 40 wt% and 60 wt% water content in the DN hydrogels (having 100% AM content in the second network). On the other hand, the tensile strength of the control single network crosslinked polyacrylamide (CPAM) hydrogels (no double network) was observed to be 280.9. kPa for 20 wt% and 112.6 kPa for 40 wt% water content in the hydrogel. Therefore, about 30% and 62% improvement of mechanical properties is observed in these cases due to DN hydrogels. High tensile strength of the DN hydrogels may be attributed to the reinforcing influence of PVA-borax complex onto the P(AM-co-HEMA) network. Such a DN hydrogel is observed to be 13 times of the stretchable cycle of its double length. The mechanical properties of the DN hydrogels varies not only with the composition of second network of P(AM-co-HEMA) but also by the influence of H-bonding. Optimum mechanical properties are observed at the composition of AM/HEMA 30/70 to 75/25 in the DN hydrogels. The influence of H-bonding is more prominent in case of lower water content in the hydrogels than that of the hydrogels having more water content. (C) 2017 Published by Elsevier Ltd.

关键词： Oat beta-glucan   Solubility   Oat structure   Viscosity flow behaviour   Molecular weight  

摘要： Oat mixed-linkage beta-glucan has been shown to lower fasting blood cholesterol concentrations due notably to an increase in digesta viscosity in the proximal gut. To exert its action, the polysaccharide has to be released from the food matrix and hydrated. The dissolution kinetics of beta-glucan from three oat materials, varying in their structure, composition and degree of processing, was investigated by incubating the oats at 37 degrees C over multiple time points (up to 72 h). The samples were analysed for beta-glucan content, weight-average molecular weight and rheological behaviour. Regardless of the materials studied and the processing applied, the solubilisation of beta-glucan was not complete. Mechanical and hydrothermal processing led to differences in the viscosity flow curves of the recovered solutions, with the presence of particulates having a marked effect. This study revealed that the structure and processing methods applied to oat materials resulted in varied and complex rheological properties, especially when particulates are present. (c) 2017 The Authors. Published by Elsevier Ltd.

摘要： Left bundle branch block (LBBB) causes left ventricular (LV) dyssynchrony which is often associated with heart failure. A significant proportion of heart failure patients do not demonstrate clinical improvement despite cardiac resynchronization therapy (CRT). How LBBB-related effects on LV diastolic function may contribute to those therapeutic failures has not been clarified. We hypothesized that LV hemodynamic forces calculated from 4D flow MRI could serve as a marker of diastolic mechanical dyssynchrony in LBBB hearts. MRI data were acquired in heart failure patients with LBBB or matched patients without LBBB. LV pressure gradients were calculated from the Navier-Stokes equations. Integration of the pressure gradients over the LV volume rendered the hemodynamic forces. The findings demonstrate that the LV filling forces are more orthogonal to the main LV flow direction in heart failure patients with LBBB compared to those without LBBB during early but not late diastole. The greater the conduction abnormality the greater the discordance of LV filling force with the predominant LV flow direction (r(2) = 0.49). Such unique flow-specific measures of mechanical dyssynchrony may serve as an additional tool for considering the risks imposed by conduction abnormalities in heart failure patients and prove to be useful in predicting response to CRT.

标准号: LY/T 1619-2017

摘要： 本标准界定了以汽油机为动力的手持式绿篱修剪机(以下简称为“绿篱机，’)的术语和定义，规定了型号编制方法、技术要求及试验方法、检验规则、标志、使用说明书、包装、运输和贮存。本标准适用于由汽油机驱动的使用线性往复式割刀修剪绿篱的绿篱机。

标准号: LY/T 1808-2017

摘要： 本标准规定了以汽油机为动力的便携杆式修枝锯(以下简称“修枝锯’)的术语和定义、型号编制方法、技术要求及试验方法、检验规则、标志、使用说明书、包装、运输和贮存。本标准适用于动力装置为侧挂或背负的修枝锯。

标准号: LY/T 2887-2017

摘要： 本标准规定了以汽油机为动力的轴向振动钩式长杆采摘机(以下简称“采摘机”)的术语和定义、型号编制方法、技术要求及试验方法、检验规则、标志、使用说明书、包装、运输和贮存。本标准适用于侧挂式、通过工作头轴向振动以采摘果实的机器。