化学气相淀积块状多晶硅电导的Arrhenius特性

在280～470K温度范围内,测试了由硅烷(SiH_4)在820～840℃温度下进行化学气相淀积的块状多晶硅的零偏压电阻,此电阻率是温度的函数。实验发现,掺磷浓度在≤1.0×10~(13)～5.0×10~(18)cm(-3)范围内的样品,当测试温度T大于特征温度T_c时,其logρ～1/T关系均具有明显呈现Arrhenius特性的区域,能够获得确定的激活能值。实验结果与Sager等人提出的激活能与掺杂浓度关系的理论表达式符合得很好。     

Nature's sunscreen from the Great Barrier Reef, Australia

All shallow-water marine organisms have natural features and behaviours that can reduce exposure to UV radiation and limit the amount of photodamage to functional biomolecules and organelles. Protection from UV radiation often includes the production of UV-absorbing compounds which, in marine organisms, are usually mycosporine-like amino acids (MAAs) having a range of absorption maxima between 310 and 360 nm. Shallow-water corals produce large quantities of MAAs and their apparent ability to withstand long-term environmental UV exposure suggests utilization of their UV-absorbing chromophore for sunscreen applications. We present an overview of the biochemical photophysiology of tropical reef-building corals, and of the development of a new class of synthetic sunscreen, 1-alkyl-3-alkanoyl-1,4,5,6-tetrahydropyridines, based on their natural UV protection. Several sunscreen candidates have been examined for sunscreen suitability and a limited selection is being tested for potential use in human skin-care and cosmetic products.     

新型液压自动抓梁对位装置设计研究

在调研传统液压自动抓梁在水利水电工程中应用情况的基础上,分析了液压自动抓梁吊轴中心与水工钢闸门吊耳孔中心对位的原理与过程。并针对传统液压自动抓梁在对位设计上存在的不足,提出了一种基于"柔性调速"的设计思想,采用"过程控制"以实现液压自动抓梁吊轴中心与闸门吊耳孔中心自动对位的结构设计。该新型结构对传统液压自动抓梁对位装置系统进行了必要的改进,既可较好地保证对位精准度,同时也有效地保护了闸门及液压自动抓梁的设备安全。     

阻隔性包装容器材料的研究与应用

综述了国内外塑料啤酒瓶材料的研制情况及超高分子聚乙烯（UHMWPE）耐腐蚀包装材料的应用和发展，并探讨其未来发展趋势。     

高阻隔性塑料包装材料的研究进展

概述了我国阻隔性塑料包装材料的现况和发展，重点介绍了PVDC，EVOH，PEN，PA等几种阻隔塑料的开发情况，并探讨其未来发展趋势。     

Electrochemical impedance spectroscopic study of barrier layer thinning in nanostructured aluminium

The electrochemical behaviour of electropolished and anodised aluminium was studied by electrochemical impedance spectroscopy (EIS). Freshly electropolished aluminium behaves as a pure capacitor exhibiting Warburg impedance at low frequencies. Storage of the electropolished aluminium, even in an air-tight bottle, results in the reconstruction of a uniform compact barrier layer. The impedance response of a stored electropolished aluminium as well as anodised aluminium after oxide removal, done by chemical etching, exhibits only a capacitive loop in the complex plane. The effect of the oxide layer thickness on the impedance data was investigated for layers formed during anodising at a cell potential of 15 or 23 V. Impedance measurements carried out over a wide range of frequencies gave useful information on the efficiency of the thinning of the barrier layer at the bottom of porous aluminium oxide layers. The rate of thinning of the barrier layer was estimated for samples anodised at different voltage.     

Characterization of waterborne acrylic based paint films and measurement of their water vapor permeabilities

Recently, production of waterborne coatings has increased significantly as a consequence of strict pollution regulations. Waterborne coatings are sensitive to humidity, thus, their barrier properties with respect to permeation of moisture needs to be determined. Among various coating constituents, binder represents the matrix structure and its amount relative to the amounts of pigments and fillers can significantly affect the structure, hence the barrier property of the coating. In this study, waterborne acrylic based paints applied as protective coating on interior and exterior wall of the buildings are studied. The paint samples formulated with four different binder contents by a commercial paint company are used in the experiments. We first determine unknown ingredients of the paint samples using different characterization tools and then investigate the effect of the binder content on the structure of the paint films. In addition, water vapor permeability of the paint films is measured using a permeation cell. Results show that the barrier property of the waterborne acrylic based paint films against humidity decreases with decreased binder content due to uneven distribution of the pigments, consequently, porous structure formation in the films.     

Barrier property and morphology of polypropylene/polyamide blend film

The barrier property of polypropylene (PP)/polyamide (PA) blend film produced by the extrusion casting film process was studied by investigating the effects of rheological properties of each components, compatibilizer content, screw rpm, and the absorbed moisture, and by performing morphological analysis and permeability modeling. The oxygen barrier property of blend film with ellipsoidal structure of PA dispersed phase was significantly improved by a factor of 5.4 with the addition of only 20 wt% PA, when compatibilizer was added by the content of 7 phr and the PP matrix resin and process condition was selected to induce lower viscosity ratio less than unity. Using Fricke’s model with the value of 19.6 of aspect ratio of the ellipsoid, the permeabilities of blend films as a function of PA content could be predicted and exhibited a good agreement with the experimental results. The absorbed moisture had a significant influence on the barrier property of the PP/PA blend system, suggesting that the hygroscopic PA resin should be incorporated with the high water barrier PP resin by the amount below about 20 wt% to minimize the deterioration of the barrier property in the humid atmosphere.     

Vapex—Gravity-assisted Film Drainage for Heavy Oil Recovery

Reservoir heavy oils of viscosity higher than 20 cp are difficult to recover efficiently. A new vapor extraction process called Vapex which uses horizontal wells and volatile solvents is being developed, primarily in Canada. This process lowers the viscosity of the oil by dilution and the oil is produced by gravity drainage (vertical movement of fluids) to horizontal wells placed low in the reservoir. More oil should be produced at lower production and energy costs. The Vapex process is outlined in this article and followed by some experimental work demonstrating gravity drainage flow in films at the macro- and micro-scale.     

Correlation between barrier heights and ideality factors of H-terminated Sn/p-Si(1 0 0) Schottky barrier diodes

Schottky barrier diodes (SBDs) were prepared by evaporation on H-terminated p-Si(1 0 0) surfaces. The Si(1 0 0)-H surfaces were obtained by wet chemical etching in diluted hydrofluoric acid. The current–voltage (I–V) characteristics of real SBDs are described by using two fitting parameters that are the effective barrier height (EBH) and ideality factor n. They were determined from I–V characteristics of SBDs (30 diodes) fabricated under experimentally identical conditions. The obtained values of EBHs varied from 0.729 to 0.749 eV, and the values of ideality factors varied from 1.083 to 1.119. The results showed that both parameters of SBDs differ from one diode to another even if they are identically prepared. The EBH distributions were fitted by two Gaussian distribution functions, and their mean values were found to be 0.739 ± 0.003 eV and 0.733 ± 0.001 eV, respectively. The homogeneous barrier height of SBDs was found to be 0.770 eV from the linear relationship between EBHs () and ideality factors (n).