通过微细观结构分析、低场核磁共振量化研究,科学、准确地描述膏体跨尺度颗粒群存在形态与水分赋存状态,并基于有限元和离散元耦合数值分析方法分析了泵压扰动下膏体颗粒流态演化规律.研究发现,膏体料浆中的吸附水、间隙水和弱自由水存...通过微细观结构分析、低场核磁共振量化研究,科学、准确地描述膏体跨尺度颗粒群存在形态与水分赋存状态,并基于有限元和离散元耦合数值分析方法分析了泵压扰动下膏体颗粒流态演化规律.研究发现,膏体料浆中的吸附水、间隙水和弱自由水存在动态连通与转化行为,并主要以吸附水形式存在,低场核磁共振技术(Low-field nuclear magnetic resonance,LF-NMR)弛豫强度与吸附水峰面积非线性增强,与料浆的流动表现出显著的正相关性.液网结构与絮网结构反映了导水通道的活跃性与力链结构的强度,共同组成了膏体稳定性与流动性的双支撑骨架结构.通过Fluent-EDEM软件耦合模拟,分析了脉冲泵压环境颗粒运动行为,在速度差的影响下高、低流速颗粒冲击扰动加剧,力链接触作用增强,流态均匀性和整体颗粒运动稳定性可有效提高.展开更多
To study the seismic performance of double-skin steelconcrete composite box（ DSCB） piers, a total of 11 DSCB pier specimens were tested under bidirectional cyclic loading. The effects of the loading pattern, the ste...To study the seismic performance of double-skin steelconcrete composite box（ DSCB） piers, a total of 11 DSCB pier specimens were tested under bidirectional cyclic loading. The effects of the loading pattern, the steel plate thickness, the axial load ratio, the slenderness ratio and the aspect ratio were taken into consideration. The damage evolution process and failure modes of the tested specimens are presented in detail. Test results are also discussed in terms of the hysteretic curve, skeleton curve, ductility and energy dissipation capacity of DSCB pier specimens. It can be concluded that the hysteretic performance of DSCB piers in one direction is affected and weakened by the cyclic loading in the other direction. DSCB piers under bidirectional cyclic loading exhibit good performance in terms of load carrying capacity, ductility, and energy dissipation capacity. Overall, DSCB piers can meet the basic aseismic requirements. The research results can be taken as a reference for using DSCB piers as high piers in bridges in strong earthquakeprone areas.展开更多
A novel floating osmotic pump controlled release system （FOP） and traditional matrix sustained release tablets （MT） of dipyridamole （DIP） were characterized in terms of pharmacokinetics, drug release, and in vit...A novel floating osmotic pump controlled release system （FOP） and traditional matrix sustained release tablets （MT） of dipyridamole （DIP） were characterized in terms of pharmacokinetics, drug release, and in vitro-in vivo correlation. In vivo study was performed by a three-crossover study in six beagle dogs relative to the conventional tablet （CT）. A HPLC method for the determination of DIP in the plasma was developed. Cumulative percent of absorption fraction was compared to that of in vitro cumulative release. Both FOP and MT displayed obvious extended release characteristic in vivo while FOP showed a better extended release behavior. The bioavailability of FOP was higher than that of MT and a zero-order release linear correlation of DIP between fraction absorbed in vivo and fraction dissolved in vitro was established for FOP while not for MT. The results indicated the existence of an absorption window in upper part of the GI track of DIP, which meant that floating system could be excellent for the drug delivery. In addition, the in vitro model was a good choice for depicting in vivo absorption and for optimization of the formulation of FOP if it is needed to be bio-equivalent to MT.展开更多
文摘通过微细观结构分析、低场核磁共振量化研究,科学、准确地描述膏体跨尺度颗粒群存在形态与水分赋存状态,并基于有限元和离散元耦合数值分析方法分析了泵压扰动下膏体颗粒流态演化规律.研究发现,膏体料浆中的吸附水、间隙水和弱自由水存在动态连通与转化行为,并主要以吸附水形式存在,低场核磁共振技术(Low-field nuclear magnetic resonance,LF-NMR)弛豫强度与吸附水峰面积非线性增强,与料浆的流动表现出显著的正相关性.液网结构与絮网结构反映了导水通道的活跃性与力链结构的强度,共同组成了膏体稳定性与流动性的双支撑骨架结构.通过Fluent-EDEM软件耦合模拟,分析了脉冲泵压环境颗粒运动行为,在速度差的影响下高、低流速颗粒冲击扰动加剧,力链接触作用增强,流态均匀性和整体颗粒运动稳定性可有效提高.
基金The National Natural Science Foundation of China(No.5117810151378112)the Doctoral Fund of Ministry of Education(No.20110092110011)
文摘To study the seismic performance of double-skin steelconcrete composite box（ DSCB） piers, a total of 11 DSCB pier specimens were tested under bidirectional cyclic loading. The effects of the loading pattern, the steel plate thickness, the axial load ratio, the slenderness ratio and the aspect ratio were taken into consideration. The damage evolution process and failure modes of the tested specimens are presented in detail. Test results are also discussed in terms of the hysteretic curve, skeleton curve, ductility and energy dissipation capacity of DSCB pier specimens. It can be concluded that the hysteretic performance of DSCB piers in one direction is affected and weakened by the cyclic loading in the other direction. DSCB piers under bidirectional cyclic loading exhibit good performance in terms of load carrying capacity, ductility, and energy dissipation capacity. Overall, DSCB piers can meet the basic aseismic requirements. The research results can be taken as a reference for using DSCB piers as high piers in bridges in strong earthquakeprone areas.
文摘A novel floating osmotic pump controlled release system （FOP） and traditional matrix sustained release tablets （MT） of dipyridamole （DIP） were characterized in terms of pharmacokinetics, drug release, and in vitro-in vivo correlation. In vivo study was performed by a three-crossover study in six beagle dogs relative to the conventional tablet （CT）. A HPLC method for the determination of DIP in the plasma was developed. Cumulative percent of absorption fraction was compared to that of in vitro cumulative release. Both FOP and MT displayed obvious extended release characteristic in vivo while FOP showed a better extended release behavior. The bioavailability of FOP was higher than that of MT and a zero-order release linear correlation of DIP between fraction absorbed in vivo and fraction dissolved in vitro was established for FOP while not for MT. The results indicated the existence of an absorption window in upper part of the GI track of DIP, which meant that floating system could be excellent for the drug delivery. In addition, the in vitro model was a good choice for depicting in vivo absorption and for optimization of the formulation of FOP if it is needed to be bio-equivalent to MT.
