利用倏逝波的有效穿透深度推导Goos-Hnchen位移

利用电磁波在界面上发生全反射倏逝波的有效穿透深度推导出了Goos-H nchen位移,并提出了一个与实际全反射过程等效的假设.     

改性磁性壳聚糖微球对Cu2+、Cd2+和Ni2+的吸附性能

Fe3O4/ chitosan magnetic microspheres of 50 to 80 滋m were prepared using the inverse phase emulsion dispersion and chemical crosslinking technology, and then modified with ethylenediamine for use in the adsorption of heavy metal ions. The adsorption properties of the modified Fe3O4/chitosan toward Cu2+, Cd2+ and Ni2+ were investigated. It was found that the adsorption capacities of Cu2+ and Ni2+ increased with pH, and a maximum adsorption for Cd2+ occurred at pH=3. The saturated adsorption capacities calculated by Langmuir isotherms were 54.3 mg·g-1 for Cu2+, 20.4 mg·g-1 for Cd2+, and 12.4 mg·g-1 for Ni2+, respectively. The adsorption kinetics were well described by pseudo-second-order equation models. The experimental results showed that the Fe3O4/chitosan modified with ethylenediamine presented higher adsorption selectivity for Cu2+ than for Cd2+ and Ni2+ in all studied pH ranges.     

高分散在氮掺杂碳纳米管表面铂纳米粒子的高效甲醇电氧化性能

以氮掺杂碳纳米管（NCNT）为载体,利用掺杂氮原子的锚定作用,通过微波辅助乙二醇还原法方便地将Pt纳米粒子高分散地固载于NCNT表面,制得了Pt/NCNT系列催化剂,对催化剂制备规律、电催化甲醇氧化反应（MOR）性能及构效关系开展了系统深入的研究。结果表明,随Pt负载量在18.2%~58.7%（w/w,下同）范围增加,Pt纳米粒子的粒径在2.2~3.7 nm范围相应地逐渐增大。单位质量催化剂的MOR催化活性先增加后急剧减小,在负载量为47.8%时达到最大。Pt的质量比活性在中等负载量（27.6%~47.8%）区间出现高值平台。该变化规律源于Pt纳米粒子的MOR催化活性在3 nm前后的明显差异,即<3 nm时活性差,>3 nm时活性优异。高负载量（58.7%）时活性的急剧下降源于Pt纳米粒子因团聚引起的Pt利用率的降低。     

纳米结构电学性质的静电力显微镜研究方法

纳米尺度的材料具有许多不同于宏观体材料的奇特的物理和化学特性.了解纳米结构的物性随材料尺寸及形状的变化关系,对于设计和合成具有特定功能的纳米材料有重要的指导意义.静电力显微镜技术为研究微纳米尺度下材料的电学特性提供了强有力的工具.文章介绍了这种测量技术的基本原理,并列举了几种在静电力显微镜基础上发展起来的纳米材料电学性...     

Hydrodynamic boundary conditions and dynamic forces between bubbles and surfaces

Dynamic forces between a 50 microm radius bubble driven towards and from a mica plate using an atomic force microscope in electrolyte and in surfactant exhibit different hydrodynamic boundary conditions at the bubble surface. In added surfactant, the forces are consistent with the no-slip boundary condition at the mica and bubble surfaces. With no surfactant, a new boundary condition that accounts for the transport of trace surface impurities explains variations of dynamic forces at different speeds and provides a direct connection between dynamic forces and surface transport effects at the air-water interface.     

Dynamic forces between bubbles and surfaces and hydrodynamic boundary conditions

A bubble attached to the end of an atomic force microscope cantilever and driven toward or away from a flat mica surface across an aqueous film is used to characterize the dynamic force that arises from hydrodynamic drainage and electrical double layer interactions across the nanometer thick intervening aqueous film. The hydrodynamic response of the air/water interface can range from a classical fully immobile, no-slip surface in the presence of added surfactants to a partially mobile interface in an electrolyte solution without added surfactants. A model that includes the convection and diffusion of trace surface contaminants can account for the observed behavior presented. This model predicts quantitatively different interfacial dynamics to the Navier slip model that can also be used to fit dynamic force data with a post hoc choice of a slip length.     

Bubble colloidal AFM probes formed from ultrasonically generated bubbles

Here we introduce a simple and effective experimental approach to measuring the interaction forces between two small bubbles (approximately 80-140 microm) in aqueous solution during controlled collisions on the scale of micrometers to nanometers. The colloidal probe technique using atomic force microscopy (AFM) was extended to measure interaction forces between a cantilever-attached bubble and surface-attached bubbles of various sizes. By using an ultrasonic source, we generated numerous small bubbles on a mildly hydrophobic surface of a glass slide. A single bubble picked up with a strongly hydrophobized V-shaped cantilever was used as the colloidal probe. Sample force measurements were used to evaluate the pure water bubble cleanliness and the general consistency of the measurements.     

用微扰理论推算超临界流体比定容热容

本文利用统计热力学中的BH微扰理论建立数学模型,推算了Ar超临界区域比定容热容,与文献值比较平均偏差为9.54%。引入了修正函数,重新对比热容公式进行推导,再次对Ar超临界区域部分比定容热容进行计算,计算平均偏差0.39%。对CO、CO₂、CH₄等其余11种简单气体的超临界比定容热容进行计算,平均偏差在1%左右。最后给出了计算中各物质势能参数值。     

二维顶盖驱动半圆腔内流动MRT-LBM研究

本文采用多弛豫时间格子玻尔兹曼方法(multi relaxation time lattice Boltzmann method—MRT LBM)对二维顶盖驱动半圆腔内流动进行了数值模拟,得到了雷诺数为500～50000范围内半圆腔内流场分布情况。在二维顶盖驱动半圆腔流场中,随雷诺数的增大,流场内旋涡的数目逐渐增加,且流动依次呈现出稳定流、周期流、混沌流等状态。本文计算结果表明,MRT-LBM模型可显著提高计算的稳定性,适用于大范围的雷诺数流动情况。     

亚甲蓝-三乙酰基丙酮合锰(Ⅲ)配合物体系光敏化引发丙酰胺聚合反应研究

<正> 染料和三乙酰基丙酮合锰(Ⅲ)配合物(Mn(AA)_3)体系,作为聚合过程的引发物质而用于非银盐成像工艺中.Chaberek等在水溶液中研究了硫堇-二乙酰基丙酮合铜(Ⅱ)和铝(Ⅲ)体系,认为首先是金属配合物水解生成的配体发生酮-醇互交,而配体的烯醇式阴离子是引发聚合的活性物质.我们曾报道了硫堇-Mn(AA)_3体系在醇溶液中光敏化引发丙烯酰胺聚合的研究,发现在醇溶液中,敏化引发聚合的活性物质,显然不同于水溶液中的情况.本文研究了亚甲蓝-Mn(AA)_3体系在醇溶液中敏化引发丙烯酰胺聚合,表明它是比硫堇-Mn(AA)_3更为有效的光敏化引发体系.