Interactions of 1 μm latex particles with pseudomonas aeruginosa biofilms

Fluorescently labelled latex microbeads were used to study the interaction of particles with Pseudomonas aeruginosa biofilms in a continuous flow annular reactor. Beads were readily distinguished and enumerated in both intact and disaggregated biofilm samples. The fraction of beads that attached to biofilm during a 24 h period ranged from 0.001 to 0.01 and was proportional to biofilm cell carbon and to the standard deviation of biofilm thickness. Microbeads added to biofilm of steady state thickness (30 μm) were observed to be located throughout the entire biofilm depth in 24 h. Many of the microbeads that attached to biofilm shortly after bacterial inoculation (thickness of 2 μm) remained near the substratum as cells grew past and covered them. Microbeads were observed near the biofilm-substratum interface for up to 5 days after bead addition. Beads formed aggregates on biofilms, but not in bulk water. Beads captured by biofilm remained in the reactor system longer than beads that never attached to biofilm.     

碳改性SnSbCu_(0.5)/M-MCMB/C负极材料

对中间相炭微球(MCMB)进行改性,以改性MCMB(M-MCMB)为基体、柠檬酸为碳源,由化学还原法、球磨法及热裂解工艺制得Sn Sb Cu0.5/M-MCMB/C复合材料。用XRD、SEM及恒流充放电等方法研究样品、纯Sn Sb Cu0.5合金和Sn Sb Cu0.5/M-MCMB负极材料。Sn Sb Cu0.5/M-MCMB/C复合材料可缓解纯Sn Sb Cu0.5合金的体积膨胀效应,提高循环稳定性。以100 m A/g在0.01~2.00 V循环,首次放电比容量为648.51 m Ah/g,库仑效率为74.55%,第80次循环的容量保持率为80.26%。     

Effect of the Anodic Diffusion Layer on the Performance of Liquid Fuel Cells

Novel diffusion layers for liquid direct methanol fuel cells (DMFCs) are designed and fabricated. The factors affecting the performance of DMFCs are determined. The results demonstrate that the diffusion layers made by micrometer scale particles and a hydrophilic binder can reduce the liquid sealing effect and increase the mass transfer property. The performance of DMFCs made using novel diffusion layers is greatly improved. The porous structure of such diffusion layers may improve the channels therein, which allows liquid methanol to diffuse in and gaseous CO₂ to diffuse out easily. Higher methanol concentrations can be used due to the formation of a larger three‐phase interfacial area.     

基于NTC微珠状热敏电阻的稳态测量方法

稳态导热系数测量方法的原理和数学模型简单,但热源均温性要求高和测量时间长限制了稳态导热系数测量方法的实际应用。提出一种测量导热系数的新型微球法稳态热测量方法,建立对应的物理模型和试验方法。通过熔融共混法制备不同质量分数的石墨烯 石蜡复合相变材料,并采用微球法对不同质量分数的石墨烯 石蜡复合相变材料的导热系数进行测量。测量得到样品的导热系数分别为0.278 W/(m·K）(0%)、0.330 W/（m·K）(0.5%)、0.402 W/（m·K）(1%)、0.524 W/（m·K）(2%)、0.604 W/（m·K）(3%)、0.654 W/（m·K）(4%)和0.711 W/（m·K）(5%)。该方法具有微球体积小、热源均匀、测量快、样品制备简单等优点,可应用于实际工程中相变材料和液体的原位导热系数测量。     

Processing of mesocarbon microbeads to high-performance materials: Part III. High-temperature sintering and graphitization

The sintering and graphitization behavior of mesocarbon microbeads (MCMB) at high temperatures (1900-2800 K) is investigated. It is shown that while the low temperature sintering performance of MCMB is unique, at high temperature it appears to be similar to that of conventional materials. In contrast, the obtained activation energy for MCMB high-temperature graphitization is ∼100 kcal/mol, which is smaller than that (∼240 kcal/mol) for typical carbon systems. It is concluded that the combination of such unique properties as excellent compressibility, low temperature sinterability, and rapid graphitization makes MCMB an attractive precursor for manufacturing carbon-based materials.     

In situ fabrication of carbon nanotube/mesocarbon microbead composites from coal tar pitch

Carbon nanotube/mesocarbon microbead composites have been synthesized from coal tar pitch with carbon nanotubes. How the carbon nanotubes affect the growth and the structure of mesocarbon microbeads are studied. The result shows that the size of beads decreases when more carbon nanotubes are added, and when the ratio of carbon nanotubes is set at 5%, we get the smallest sample with quite uniform shape. Carbon nanotubes exist both on the surface and inside of the samples and they will inhibit the growth and coalescence of these spheres. The addition of carbon nanotubes decreases the graphitization degree of the samples and makes their microtexture tend to be disordered.     

非均相成核中间相炭微球的形成过程及其结构演变

以含有喹啉不溶物的煤焦油沥青为原料，在410℃、不同反应时间下获得一系列中间相炭微球(MCMB)和小于0．5μm的碳质颗粒(SCP)。通过对中间相沥青的软化点、族组成和MCMB、SCP的形貌及MCMB断面结构的分析，认为非均相成核MCMB的形成和生长过程不同于均相成核的融并生长过程，而是SCP碳质颗粒的构筑过程，我们称之为“球形基本单元构筑”过程。在MCMB生长过程中，体系的黏度对SCP的形成和MCMB的生长起着重要的作用。非均相成核MCMB的内部结构不是三种模型结构(“地球仪”型、“洋葱”型和“同心圆”型)中的任一种，而是炭层具有收缩点的复杂结构，并且球体的结构不具有“继承性”，即随着反应时间的延长而不断发生变化和调整。MCMB内部分子在球体生长过程中的主要变化趋势是分子的不断缩合长大，而不是分子片层的平行趋向。     

微珠析出比色法在黄金开发中的应用

本文论述了微珠析出比色法在黄金勘探，化探中的应用，以及微珠析出比色法在野外快速分析中的重要作用。     

Development of Micro-Debond Methods for Thermoplastics Including Applications to Liquid Crystalline Polymers

Micro-bead and related debond techniques were used to study adhesion of liquid crystalline copolyesters (LCPs) and other semi-crystalline thermoplastic polymers to glass fibers. For polymers with poor flow even at high temperatures, symmetric beads on fibers were difficult to prepare so an alternative sample preparation method was developed where glass fibers were inserted into thin sections of molten polymer. Glass fibers of widely-varying diameters were used in order to extend the dynamic range of the debond techniques in terms of debonding area, showing a significant improvement in precision over that demonstrated previously with micro debond techniques. The fibers were freshly prepared in our laboratory and silane coated when necessary, which allowed us to minimize fiber surface heterogeneity effects which are believed to influence strongly debond test results. It was found that chemical bonding of the LCPs was quite favorable as was indicated by fracture surface analysis and by comparison with the shear strength of the neat resins. The apparent poor interphase strength in fiber-reinforced LCP composites is proposed to be due to orientation of the LCP molecules near the fiber interface leading to a cohesively weak layer of LCP near the interface. Reactive silane coupling agents lead to no improvement in interface strength as compared with bare glass because chemical reaction occurs on both surfaces. This results in very strong interfaces leading to polymer cohesive failure near the interface of all thermoplastics studied here     

中间相炭微球的二次生长

为考察中间相的形成和生长机理,将一种煤沥青制备的中间相炭微球添加到另一种沥青中进行二次热缩聚,结果发现中间相炭微球可以进行二次生长。二次热缩聚中间相炭微球的产率、粒径分布、表面和断面的形貌表明添加的中间相炭微球对于沥青热缩聚过程的物理作用更为主要;二次热缩聚过程包含了添加的中间相炭微球的二次生长过程和原料沥青独立成核生长两个相互竞争的过程,中间相炭微球的添加量对这两个过程有着重要的影响;中间相炭微球的生长是基本构筑单元不断进入相界面的构筑过程。