关键词： Hydrogels Poly (N-vinyl-2-pyrrolidone-co-2-hydroxyethyl   methacrylate)   Molecular dynamics   Simulation   Mechanical properties  

摘要： Poly (N-vinyl-2-pyrrolidone-co-2-hydroxyethyl methacrylate) (P(VP-co-HEMA)) hydrogel system with a composition of VP:HEMA=37:13 was studied using molecular dynamics simulations in order to investigate the effect of the water content on the equilibrium structures and the mechanical properties. The degree of randomness of the monomer sequence for the random and the blocky copolymers, were 1.170 and 0.104, respectively, and the degree of polymerization was fixed at 50. The equilibrated density of the hydrogel was found to be larger for the random sequence than for the blocky sequence at low water contents (<40 wt%), but this density difference decreased with increasing water content. The pair correlation function analysis shows that VP is more hydrophilic than HEMA and that the random sequence hydrogel is solvated more than the blocky sequence hydrogel at low water content, which disappears with increasing water content. Correspondingly, the water structure is more disrupted by the random sequence hydrogel at low water content but eventually develops the expected bulk water-like structure with increasing water content. From mechanical deformation simulations, stress-strain analysis showed that the VP is found to relax more efficiently, especially in the blocky sequence, so that the blocky sequence hydrogel shows less stress levels compared to the random sequence hydrogel. As the water content increases, the stress level becomes identical for both sequences. The elastic moduli of the hydrogels calculated from the constant strain energy minimization show the same trend with the stress-strain analysis. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： Mechanical activation   Reaction kinetics   Leaching recovery  

摘要： BET, SEM, and particle size analysis was used for studying the changes in surface and bulk properties of mechanically activated pyrrhotite in a vibrating mill. The results showed that mechanical activation increased microstructure defects and specific surface area of pyrrhotite, and decreased powder particle size. And the formation of aggregates was very obvious. The influence of mechanical activation on leaching kinetics of pyrrhotite by FeCl3-HCl solutions was investigated. When pyrrhotite was mechanically activated for 10 min, 20 min and 40 min, the apparent activation energy decreased from 133 kJ/mol to 33, 26 and 25 kJ/mol, respectively. Compared with the non-mechanical activation method, mechanical activation greatly improved the activity of pyrrhotite and decreased the apparent activation energy, so that the reaction speed was accelerated remarkably. (C) 2009 Published by Elsevier B.V.

ISBN: (纸本)9787508468631

关键词： Acid Orange 7   Clogging   VFCW modelling   Hydrology   Intermittent feeding mode   Model sensitivity analysis   Phragmites australis  

摘要： A simple mechanistic model of a pulse-fed vertical flow constructed wetland is presented. In this work, the model is shown to accurately reproduce measurements of outlet flow and outlet concentration obtained while treating a synthetic wastewater containing the azo-dye, Acid Orange 7 (AO7). Application of the model to results obtained in summer and winter gave a unique apparent first-order kinetic constant (4.1 x 10(-7) s(-1)), indicating that the activation energy is low. The treatment efficiencies determined while operating in a pseudo-stationary state for a high AO7 inlet concentration of 692 +/- 92 mg L-1 were 68 +/- 5 and 70 +/- 21% in summer and winter, respectively, for a flooding level of 21% and a pulse feeding of 13 min each 3 h. At the end of these trials (lasting more than I year), the system clogged. This occurrence was accurately modelled by including a variation in the free surface area with the liquid height above the bed surface. The model was then applied to design a robust dye wastewater treatment system producing water suitable for discharge to aquatic bodies. Model sensitivity to positive and negative evapotranspiration, that mimic variations in rainfall and temperature, and to variations in the rate constant, accounting for different azo-dyes biodegradability, was analyzed. (C) 2009 Elsevier B.V. All rights reserved.

关键词： 事故预防   切削工具   定义(术语)   英语   林业   林业设备   林业机械   高速切削装置   内燃机   修枝锯   机械性能   机械测试   电动的   发动机   噪声测量值   操作说明书   便携的   动力传动系统   危险防护   修枝剪刀   安全装置   安全设备   机械安全性   安全性要求   锯   规范(验收)   测试   树木采伐   用户信息   林地培育   木锯   木材加工   工作场所安全性  

标准号: BS EN ISO 11680-2-2008

关键词： 磨蚀试验   验收   验收(鉴定)   验收规范   农业工程   农用设备   农业机械   农用拖拉机   农业   环境温度   万向轴   检查设备   低温试验   定义(术语)   交货条件   主动轴   英语   设备安全性   林业   漏斗   冲击测试   连接件   实验室测试   负荷   机械   机械工程   摆动件   螺旋桨轴   保护设备   保护装置   减震系统(防护)   安全组件   安全装置   机械安全性   轴   筛分设备   材料强度   强度试验   温度   试验报告   测试   测试条件   测试装置   测试规程   牵引车   磨损   耐磨性   磨损试验   宽度  

标准号: BS EN ISO 5674-2009

摘要： Agricultural tractors;Agricultural equipment;Tractors;Forestry equipment;Power take-off;Drive shafts;Machine guards;Safety devices;Power transmission systems;Mechanical testing;Impact testing;Endurance testing;Wear tests;Wear resistance;Stre

关键词： 事故预防   切削工具   定义(术语)   英语   林业   林业设备   林业机械   高速切削装置   手动装置   集成的   内燃机   修枝机   作标记   机械性能   机械测试   电动的   噪声测量值   操作说明书   便携的   动力传动系统   危险防护   修枝剪刀   安全装置   安全设备   安全性要求   锯   规范(验收)   测试   树木采伐   用户信息   林地培育   木锯   木材加工   工作场所安全性  

标准号: BS EN ISO 11680-1-2008

关键词： CELL migration   ACTIN   CYTOSKELETON   CELLULAR immunity   PHAGOCYTOSIS   DEVELOPMENTAL cytology   CELL membranes  

摘要： Cell migration is an essential feature of eukaryotic life, required for processes ranging from feeding and phagoctyosis to development, healing, and immunity. Migration requires the actin cytoskeleton, specifically the localized polymerization of actin filaments underneath the plasma membrane. Here we summarize recent developments in actin biology that particularly affect structures at the leading edge of the cell, including the structure of actin branches, the multiple pathways that lead to cytoskeleton assembly and disassembly, and the role of blebs. Future progress depends on connecting these processes and components to the dynamic behavior of the whole cell in three dimensions.

关键词： Bell model   L-selectin   Adhesive dynamics   Cell adhesion   Mechanical shedding  

摘要： Here we accurately recreate the mechanical shedding of L-selectin and its effect on the rolling behavior of neutrophils in vitro using the adhesive dynamics simulation by incorporating the shear-dependent shedding of L-selectin . we have previously shown that constitutively expressed L-selectin is cleaved from the neutrophil surface during rolling on a sialyl Lewis x-coated planar surface at physiological shear rates without the addition of exogenous stimuli. Utilizing a Bell-like model to describe a shedding rate which presumably increases exponentially with force, we were able to reconstruct the characteristics of L-selectin-mediated neutrophil rolling observed in the experiments. First, the rolling velocity was found to increase during rolling due to the mechanical shedding of L-selectin . When most of the L-selectin concentrated on the tips of deformable microvilli was cleaved by force exerted on the L-selectin bonds, the cell detached from the reactive plane to join the free stream as observed in the experiments. In summary, we show through detailed computational modeling that the force-dependent shedding of L-selectin can explain the rolling behavior of neutrophils mediated by L-selectin in vitro. (C) 2009 Elsevier Ltd. All rights reserved.

标准号: NF E52-615/IN1-2009