熔铸-原位反应法生成α-Al2O3晶须的形貌及结晶方向

利用熔铸－原位反应法制备TiC/Al复合材料时，发现Ti-C-Al反应块表面存在大量的Al2O3晶须，晶须的形貌包括长而直的板状和串珠状，取决于反应进行时铝熔体的温度，当铝熔体温度低于900℃时，形成板状晶须，而当铝熔体温度高于900℃时，形成串珠状的晶须，其原因是由于较高的铝熔体温度加剧了TiC原位反应的放热，热起伏的结果致使部分α－Al2O3晶须异常长大，X射线衍射和透射电镜分析确认晶须为α－Al2O3，其形貌以直板状为主，电子衍射花样斑点显示其结晶方向为[0002]。     

基于M估计的非线性鲁棒检测卡尔曼滤波算法

针对传统鲁棒非线性滤波在观测噪声为非高斯强干扰噪声情况下,滤波性能下降的问题,提出一种利用卡方检测法预判断的非线性鲁棒检测滤波算法。该算法通过卡方检测设置门限,剔除突变野值,利用M估计修正量测更新。仿真实验对比了几种典型非线性滤波方法在不同观测噪声环境下的性能。所提算法在非高斯强干扰噪声情况下,比传统鲁棒滤波算法估计精度平均提高了25.5%;估计方差平均减少了18.3%。实验结果表明:所提算法可以抑制观测量非高斯强干扰噪声的影响,提高滤波精度及稳定性。     

Hydrolysis of human horny cells by alkaline protease: Morphological observation of the process

The interaction of highly purified alkaline protease fromBacillus sp. KSM-K16 with the horny cells of human skin contained in skin grime was directly visualized by electron microscopy. It became clear that the protease first penetrates the horny cells and then adsorbs, mainly onto the internal structure of the cells at the initial stage of hydrolysis, and directly hydrolyzes the keratin filaments, though the marginal band surrounding them retains its original shape. Then, hydrolysate produced from the keratin filaments flows out of the cell, and early in the hydrolysis process keratin filaments decrease and then disappear, leaving a marginal band, i.e., the cell turns to a hollow state. As a result, the remaining marginal band loses support from inside the cell, thus promoting cleavage and dispersion. Until this stage in the protease reaction, the remarkable liberation of hydrolysis products as water-soluble protein does not occur.     

聚甲基丙烯酸甲酯／纳米SiO2复合粒子的制备与表征

采用甲基丙烯酸-3-甲氧基硅丙酯（MPs）对分散于甲基丙烯酸甲酯（MMA）中的纳米SiO2粒子进行偶联改性，得到了表面改性的纳米SiO2单体分散液，用原位悬浮聚合方法制备了不同SiO2含量的PMMA／纳米SiO2复合粒子。通过红外光谱、透射电镜、差示扫描量热分析和热重分析等方法对制备的纳米复合粒子进行了表征，结果表明，纳米SiO2粒子在PMMA中分散良好；MMA可通过与MPS的共聚而有效地接枝到SiO2粒子表面，当SiO2含量为6．6％（质量分数，下同）、MPS用量为0．06g／gSiO2时，其接枝率可达73．8％；同时，纳米SiO2的引入可提高PMMA的耐热性能，当Si02含量为14.7％时，其玻璃化转变温度和最大热分解速率时的温度分别提高了11．8℃和18．8℃。     

PVC-U异型材塑化度的评价

比较了4种评价PVC-U塑化度的方法:目测法简单;溶剂法迅速,容易操作;拉伸法可定量判断,但需要大量样品;DSC法准确、方便。     

聚苯胺/涤纶导电织物再掺杂及洗涤性能的研究

采用现场吸附聚合法制备了聚苯胺 /涤纶导电织物 ,采用不同种类的酸对其进行再掺杂 ,研究了酸的种类对织物导电性能的影响 ,并对导电织物进行了洗涤实验及洗涤牢度实验。结果表明 :无机酸对导电织物的掺杂效果优于大多数有机酸。导电涤纶织物的导电性能受洗涤液酸碱度的影响 ,其中碱性洗涤液使导电性能降低 2个数量级 ,酸性洗涤液使导电性能下降 1个数量级 ,而且聚苯胺在涤纶织物表面具有良好的附着性     

Competitive Reaction During Decomposition of Hexachlorobenzene Over Ultrafine Ca–Fe Composite Oxide Catalyst

The decomposition of hexachlorobenzene (HCB) has been investigated over ultrafine Ca–Fe composite oxide catalyst (Ca/Fe atomic ratio was 3.4), CaO and α-Fe₂O₃ by using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Adsorption experiments on the surface of oxides monitored by in situ DRIFTS showed that partial oxidation products, i.e., phenolate and acetate species were formed on the surface of Ca–Fe composite oxide. The further studies indicated that Ca–Fe composite oxide catalyst was easier to induce the rupture of C–Cl bond and C–C bond of aromatic rings. The best catalytic activity of Ca–Fe composite oxide may be related to the acidity, which was determined by NH₃–TPD. The products after reaction have been analyzed by XRD and chloride selective electrode. Ca–Fe composite oxide exhibited the highest extent of mineralization for organic chlorine among the different oxides tested. The combined results of current and previous experiments demonstrated that two competitive reactions took place during the decomposition process of HCB: (1) hydrodechlorination resulting in the formation of lower chlorinated benzenes and (2) oxidation of aromatic rings leading to the rupture of aromaticity and the formation of oxidation products. The latter is the major process in the coexisted competitive reaction. A possible decomposition pathway was discussed.     

Thermotropic liquid crystalline polymer (Rodrun LC5000)/polypropylene in situ composite films: rheology, morphology, molecular orientation and tensile properties

In situ composite films were prepared by a two-step method. First, polypropylene and thermotropic liquid crystalline polymer (TLCP), Rodrun LC5000 (80 mol% p-hydroxy benzoic acid (HBA)/20 mol% polyethylene terephthalate (PET)), were melt blended in a twin-screw extruder and then fabricated by extrusion through a mini-extruder as cast film. Rheological behavior of the blends, morphology of the extruded strands and films, and tensile properties of the in situ composite films were investigated. Rheological behavior of the blends at 295 °C studied using a plate-and-plate rheometer revealed a substantial reduction of the complex viscosity with increasing TLCP content, and all specimens exhibited shear thinning behavior. Over the angular frequency range of 0.6-200 rad/s, the viscosity ratio (dispersed phase to matrix phase) was found to be very low, in the range of 0.03-0.07. Morphologies of the fracture surfaces of the blend extrudates and the film surfaces etched in permanganic solution were investigated by scanning electron microscope (SEM). The TLCP droplets in the extruded strands were seen with a progressive deformation into fibrillar structure when TLCP content was increased up to 30 wt%. In the extruded films, TLCP fibrils with increasing aspect ratio (length to width) were observed with increasing TLCP concentration. Orientation functions of each component were determined by X-ray diffraction using a novel separation technique. It was observed that the Young's modulus in machine direction of the extruded film was greatly improved with increasing TLCP loading, due to the increase in fiber aspect ratio and also molecular orientation.     

Adsorption mode of ethyl pyruvate on platinum: an in situ XANES study

The adsorption of ethyl pyruvate on Pt(111) has been studied by in situ XANES measurements in the presence and absence of hydrogen. Depending on the hydrogen and ethyl pyruvate pressure, the C and O K‐edge spectra exhibit distinctly different angular dependence. Without hydrogen ethyl pyruvate is oriented preferentially perpendicular to the surface, indicating bonding via the O lone pairs. In the presence of hydrogen the mean orientation is more tilted towards the surface. Likely, ethyl pyruvate also interacts with Pt via its π system under these conditions. The observed angle‐dependent shift of the energy of the π* and σ* resonances indicates the coexistence of differently adsorbed ethyl pyruvate species. The experimental findings demonstrate the importance of the in situ approach for unraveling the adsorption mode of ethyl pyruvate in the enantioselective hydrogenation over cinchona‐alkaloid‐modified Pt. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal cure monitoring of phenolic resole resins based on in situ fluorescence technique

The thermal curing reaction of two phenolic resole resins is monitored using the fluorescence technique. The intrinsic fluorescence can be used as an indicator for cure monitoring for the first resole. As the thermal curing proceeds, the intrinsic fluorescence intensity of the resole resin decreases and exhibits a few nanometers of redshift. The fluorescence intensity of the emission maxima is correlated with the conversion measured by differential scanning spectroscopy. A linear correlation is found at three different temperatures. The intrinsic fluorescence cannot always be used for monitoring the curing process of phenolic resole resins. Thus, three intramolecular charge transfer compounds and two organic donor–π‐acceptor salts are selected and applied for the cure monitoring of the second phenolic resole resin. As the curing reaction proceeds, the fluorescence emission spectra of the probes exhibit a blue spectral shift and the intensity changes because of environmental changes. An intensity ratio method is applied in which the ratios of the low‐ to high‐intensity changes in the emission bands are used to determine the degree of the curing process. There is a smooth correlation between the intensity ratio method and the degree of cure. The method enables one to follow the changes in the polymer structure at low and intermediate degrees of the curing process (below 70%) and obtain comparable results from different types of probes during the same curing process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1773–1780, 2002