Ozonation of Selected Molecules Constituting Cellular Matter

Ozonation of purine and pyrimidine bases and of carbohydrates was studies in laboratory experiments. The results showed that nucleobases are much more reactive with molecular ozone in aqueous solution than carbohydrates. Second order rate constants for direct reaction of ozone on purines (adenine and guanine) and on pyrimidines (cytosine, thymine and uracil) ranged from 0.76 × 10³ to 6.8 × 10³ M^-1s^-1at 2°C. The difference of reactivity between these solutes may be attributed to their substituents. As far as carbohydrates are concerned, direct reactions of ozone are very slow k₀₃ ? 0.1 – 0.3 M_-1s_-1 at 20°C, and the results indicated that free radical reactions are predominant in the degradation pathway of carbohydrates by ozone. Some ozonation by-products of monosaccharides (glucose, xylose) and disaccharides (cellobiose) also were identified in this study by means of GC/MS analyses.     

Influence of maize kernel hardness on flour hydration and cooking properties

Knowledge of the association between cooking properties and endosperm hardness may help nutritionist and processors to select raw materials for preparing maize based food products, particularly those eaten as cooked dispersions. Seven commercial maize cultivars differing in hardness were selected to evaluate endosperm hardness on the kernels and some characteristics such as composition and hydration and cooking properties on the grits obtained from those maizes. Results show that the differences in endosperm hardness (directly related to grits protein content) can explain the differences in swelling and amylographic consistencies values. Cultivars with the hardest endosperm show the lowest values at high temperature. They also show the lowest amylographic consistencies. On the other hand softer endosperms present the highest swelling power and the highest amylographic consistencies. These differences are attributed to the restriction for starch swelling caused by the protein matrix. Endosperm hardness measurements and swelling power at 95 degrees C, can be useful to select cultivars that are going to be used to prepare maize based foods like atoles, polenta, etc.     

Molecular orientation in drawn smectic and crystalline isotactic polypropylene

The drawing behavior of two polypropylene films of different structures was analyzed. The two films differ as a consequence of different quenching conditions. At low temperature, a biphasic smectic-amorphous system was obtained, while quenching at 100°C produced a biphasic crystalline-amorphous system. The drawing of samples was carried out at 110°C at which temperature the smectic phase is not stable and is transformed into the crystalline α-form. The initial structure affects the drawing behavior and the properties of the drawn samples. The mechanical, optical, and X-ray analyses clearly show that high molecular orientation is achieved at lower deformations in the initially smectic sample. In particular, the amorphous phase is highly oriented, inducing higher axial elastic modulus.     

A/O法废水处理碱源的研究与实践

从理论到实践阐述了以具有价格优势的 Na OH替代 Na2 CO3做碱源 ,解决 A / O法运行成本高的问题。     

色谱顶空法测活度系数及对三元极性体系液液平衡预测

用气相色谱顶空分析法测定 18组部分互溶三元极性体系在完全互溶区的 3个组分活度系数 ,由此拟合出 U NIQU AC过量自由焓模型参数 ,再用 U NIQUAC方程预测液液平衡。这一方法曾很好地用在水-正烷烃 -醇体系。将此法拓展到含醇、酮、酯 ,醚、卤烷烃和水等多种极性组分的三元体系液液平衡的预测 ,其结果与文献的液液平衡数据比较 ,平均均方根误差 1.4 1% ,表明本法对含极性组分的体系仍然可行     

Melt‐processable rubber: Chlorinated waste tire rubber‐filled polyvinyl chloride

Chlorinated ground rubber tire (Cl‐GRT) particles were used as filler in a plasticized polyvinylchloride (PVC) to develop a melt‐processable rubber composition. Physical properties of the Cl‐GRT‐filled PVC compound showed improvement compared to the nonchlorinated counterpart. Interaction between Cl‐GRT and PVC was examined on the basis of results of stress relaxation, dynamic mechanical thermal analysis, and solvent swelling studies. The Cl‐GRT could be loaded upto 40 parts per hundred parts of PVC, and the composition still retains the elastomeric characteristics. The Cl‐GRT‐filled composite was found to be reprocessable like the unfilled PVC compound. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 622–631, 2002; DOI 10.1002/app.10352     

Factors influencing magnetic polymer microspheres prepared by dispersion polymerization

Magnetic iron oxide (Fe₃O₄) was prepared by a coprecipitation method. Core–shell composite magnetic polymer microspheres with carboxyl groups were synthesized by the dispersion polymerization of styrene and acrylic acid in the presence of magnetic oxide, and dibenzoyl peroxide was used as an initiator. The synthesized magnetic polymer microspheres were characterized with X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and so forth. The results indicated that the product was single‐phase Fe₃O₄, and its average size was about 10 nm. The configuration of the microspheres, which contained carboxyl groups, was spherical, and the average size was about 2 μm. The results of vibrating sample magnetometry tests showed that the magnetic powders produced by different surfactants had different saturation magnetizations. When poly(ethylene glycol) with a weight‐average molecular weight of 4000 was used as a surfactant, the saturation magnetization of the samples reached 69.2 emu/g. The factors that affected the shape, magnetism, size, and distribution of the microspheres were also studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

企业网站设计内容第一的原则

企业网站设计内容第一的原则,其根本在于企业网站能否吸引和留住客户或潜在客户,它包含三层意思：网站内容的面向对象要准确清晰;针对目标访客的网站内容要紧扣其兴趣中心,从为其带来价值的角度出发,令其感到有收获;促使目标访客对网站内容建立起充分的信任感、解答其疑问。从网站内容方面保证了企业网站对目标访客的吸引力和访问粘度,从而为企业网站实现其既定目标打下了良好的基础。     

制镁还原罐的研制

从含镁的矿石中提炼金属镁的方法已不仅仅是电解法 ,还有目前广泛采用的真空还原法 (皮江法 ) ,但其所用的还原罐寿命短、价格高一直是困扰着国内、国外生产的难题。用研制出新的材料和改革后的铸造工艺生产出的还原罐 ,较好地解决了上述问题 ;并达到国内、国外先进水平。     

Note: Simultaneous electrical and optical detection of expanding dense partially ionized vapour clouds

The scheme and construction of an electro-optical probe able to collect charge and detect optical emission from expanding dense partially ionized vapour clouds are reported. The instrument can be applied to phenomena such as dust impact ionization and solid target laser ablation. First, results of measurements of expanding plasma cloud formed upon ablating W target are presented. Use of the instrument in different experimental facilities, including tokamak, is discussed.