Organophosphorus antioxidants action mechanisms and new trends

Phosphite and phosphonite esters can act as antioxidants by three basic mechanisms depending on their structure, the nature of the substrate to be stabilized and the reaction conditions. All phosph(on)ites are hydroperoxide-decomposing secondary antioxidants. Their efficiency in hydroperoxide reduction decreases in the order phosphonites > alkylphosphites > arylphosphites > hindered arylphosphites. Five-membered cyclic phosphites are capable of decomposing hydroperoxides catalytically due to the formation of acidic hydrogen phosphates by hydrolysis and peroxidolysis in the course of reaction. Hindered aryl phosphites can act as chain-breaking primary antioxidants being substituted by alkoxyl radicals and releasing hindered aryloxyl radicals which terminate the radical chain oxidation. At ambient temperatures, the chain-breaking antioxidant activity of aryl phosphites is lower than that of hindered phenols, because the rate of their reaction with peroxyl radicals and their stoichiometric inhibition factors are lower than those of phenols. In oxidizing media at medium temperatures, however, hydrolysis of aryl phosph(on)ites takes place giving hydrogen phosph(on)ites and phenols which are effective chain-breaking antioxidants. 2,2,6,6-Tetramethyl- and 1,2,2,6,6-Pentamethylpiperidinyl phosphites and phosphonites (HALS-phosph(on)ites) surpass many common phosphites, phenols and HALS compounds as stabilizers in the thermo- and photo-oxidation of polymers. Their superior efficiency is probably due to an intramolecular synergistic action of the HALS and the phosph(on)ite moieties of their molecules.     

聚丙烯阻燃剂的作用机理及其研究进展

本文综述了聚丙烯阻燃剂的种类和作用机理,并且介绍了聚丙烯阻燃剂的最新研究进展。聚丙烯阻燃剂的发展方向是高效、低烟、无毒、多功能、低成本。     

纤维素降解辅助蛋白及其作用机理研究进展

化石燃料的日渐枯竭及环境污染的日益严重使得生物质原料的资源化、能源化利用受到广泛关注。木质纤维素是地球上最丰富的可再生生物质,其通过生物转化可获得多种燃料和化学品,而纤维素难以有效糖化是木质纤维素生物转化的主要瓶颈。本文介绍了某些纤维素非降解性辅助蛋白提高纤维素酶解效率的相关研究进展,重点分析了近些年发现并研究较多的裂解性多糖单加氧酶（AA9和CBM33）、纤维二糖脱氢酶（CDH）、扩展蛋白（expansin）、膨胀素（SWOI）等几种纤维素辅助蛋白及其协助纤维素降解的机理,总结出这些辅助蛋白主要是通过促进木质素或半纤维素降解以及破坏纤维素的氢键网络和结构来协同纤维素酶催化纤维素的糖化降解。通过以上概括和评述,认为这些辅助蛋白虽然一定程度上可以促进纤维素的酶解,但其研究和应用还仅限于实验室基础研究,如何将其有效并廉价应用于木质纤维素生物转化的工业过程还面临着巨大挑战。指出相关研究工作的重点还需要从廉价而有效的蛋白筛选与构建、协同作用机理解析、过程优化与强化等方面深入开展。     

Alternating current and direct current conductivity of poly(azo-1,4-phenylene-vinylene-1,4-phenylene)

The electrical conductivity and dielectric properties of poly(azo-1,4-phenylene-vinylene-1,4-phenylene) were examined. The thermal activation energy of the direct current (DC) conductivity was compared with the activation energy of the relaxation process, evaluated from the area and the width of the curve of the dielectric loss factor against reciprocal temperature at constant frequency. The activation energy E_a=1.50 eV of the intrinsic DC conductivity was found to be roughly equal to the dielectric activation energy [1/H]=1,62 eV. The conduction mechanism in poly(azo-1,4-phenylene-vinylene-1,4-phenylene) is discussed.     

蛋白质与超滤膜界面作用能对膜污染机制的影响

比较了3种蛋白质引起的膜通量变化及膜污染情况,利用x DLVO理论分析了蛋白质超滤过程中的界面作用能对膜污染机制的影响。结果表明,卵清蛋白(Ovalbumin,OVA)造成的膜污染最严重,其次是牛血清白蛋白(Bovine Serum Albumin,BSA)和溶菌酶(Lysozyme,LYS);在黏附阶段和黏聚阶段,极性力自由能起主导作用,范德华力和双电层力对其贡献很小;蛋白质分子从远距离逐渐接近UF膜或滤饼层时,极性力作用能对膜污染起主导作用,总界面作用能和作用范围是影响膜污染趋势的主要因素。     

Histidine-Rich Glycoprotein Suppresses the S100A8/A9-Mediated Organotropic Metastasis of Melanoma Cells

The dissection of the complex multistep process of metastasis exposes vulnerabilities that could be exploited to prevent metastasis. To search for possible factors that favor metastatic outgrowth, we have been focusing on secretory S100A8/A9. A heterodimer complex of the S100A8 and S100A9 proteins, S100A8/A9 functions as a strong chemoattractant, growth factor, and immune suppressor, both promoting the cancer milieu at the cancer-onset site and cultivating remote, premetastatic cancer sites. We previously reported that melanoma cells show lung-tropic metastasis owing to the abundant expression of S100A8/A9 in the lung. In the present study, we addressed the question of why melanoma cells are not metastasized into the brain at significant levels in mice despite the marked induction of S100A8/A9 in the brain. We discovered the presence of plasma histidine-rich glycoprotein (HRG), a brain-metastasis suppression factor against S100A8/A9. Using S100A8/A9 as an affinity ligand, we searched for and purified the binding plasma proteins of S100A8/A9 and identified HRG as the major protein on mass spectrometric analysis. HRG prevents the binding of S100A8/A9 to the B16-BL6 melanoma cell surface via the formation of the S100A8/A9 complex. HRG also inhibited the S100A8/A9-induced migration and invasion of A375 melanoma cells. When we knocked down HRG in mice bearing skin melanoma, metastasis to both the brain and lungs was significantly enhanced. The clinical examination of plasma S100A8/A9 and HRG levels showed that lung cancer patients with brain metastasis had higher S100A8/A9 and lower HRG levels than nonmetastatic patients. These results suggest that the plasma protein HRG strongly protects the brain and lungs from the threat of melanoma metastasis.     

CO2 dry cleaning: Acoustic cavitation and other mechanisms to induce mechanical action

High pressure carbon dioxide (CO₂) is a potential solvent for textile dry cleaning. However, the particulate soil (e.g. clay, sand) removal in CO₂ is generally insufficient. Since cavitation has been proven to be beneficial in other CO₂ cleaning applications, this study aims to investigate the possibility of improving the performance of CO₂ textile dry cleaning by using ultrasound or other mechanisms to induce the mechanical action such as bubble spray and jet spray. In the experiments, several types of textiles soiled with a mixture of motor oil and soot were cleaned using 1 L and 90 L CO₂ dry cleaning set-ups. Using either ultrasound, stirring, liquid spray or bubble spray does not give a significant improvement on particulate soil removal from textile. It was also found that the additional use of ClipCOO detergent does not give a significant improvement on particulate soil removal either. The cleaning performance of CO₂ is 50% lower than that of PER and thus another method to increase the particulate soil removal in CO₂ textile dry cleaning still needs to be developed.     

新型对称双偶氮苯化合物的合成及光学性能

以联苯二胺为原料,通过重氮化、偶联和Williamson醚合成反应,设计合成了一系列新型的对称性不同端基的双偶氮类化合物,考察了溶剂、不同取代基对偶氮化合物紫外吸收影响。以4,4’-二(4-辛氧基-苯偶氮基)-联苯(Azo3)为例,在365 nm紫外光照射下发生反-顺光异构化,光照10 min后达到光稳定态,具有良好的光致变色性。     

Testing of electrochromic materials using symmetrical devices

“Symmetric materials” devices, where both electrodes are made of the same electrochromic materials, allow the in situ study of side reactions. Each transferred charge that is not used for the expected electrochromic reaction will cause a colour change in the whole symmetric device. Two electrochromic materials, WO₃ and IrO₂, are successively used to show how to obtain information about side reactions such as faradaic efficiency, reversibility and potential limits from the symmetric experiment. This in situ approach with a polymer electrolyte shows significant differences compared to results obtained with studies in aqueous electrolytes.     

Unsteady gasless combustion of planar symmetrical samples

Influence of ignition conditions on the modes of unstable combustion of planar symmetrical green samples was numerically explored in terms of 2D theoretical model. Within the range of instability, ignition conditions were found to define the number of self-propagating hot spots and their trajectories. In case of uniform distribution of ignition temperature over the inner boundary of annular sample, the combustion front propagates in the form of expanding ring.     

Recent advances and prospects of symmetrical solid oxide fuel cells

Solid oxide fuel cells (SOFCs) with symmetrical electrodes have been investigated extensively because of their potential significant advantages compared to the traditional configurations, regarding manufacturing, thermomechanical compatibility with cell components, operation stability, anting sulfur poisoning and carbon deposition. Many electrodes with novel structure and properties are currently being developed and studied in recent years. In this review, we summarized the recent advances of symmetrical SOFCs on their electrode materials, applications and prospects. The electrode materials include single phased perovskite, double perovskite, perovskite derived structures and composite electrodes. The relationships between the electrode materials and relevant properties are discussed. The applications and perspectives are highlighted, providing critical and useful directions for researchers to prepare and design electrode materials rationally.     

PAC、PFS对洗毛废水絮凝效果及作用机理的比较

作者采用PAC(聚合氯化铝)／PAM(阴离子聚丙烯酰胺)和PFS(聚合硫酸铁)／PAM两种复合絮凝剂分别进行了洗毛废水的絮凝实验研究,同时跟踪了过程中的粒径变化。实验表明：(1)PAC不仅能去除废水中的乳化胶体．还能结合游离的LAS,PFS只能去除乳化胶体;(2)PAC与废水胶体生成一次性絮体的粒径约30μm,过量的PFS却能导致絮体的解体;(3)对于LAS类洗涤废水,PAC／PAM复配絮凝效果较好,LAS去除率高达97％,COD去除率可达90％以上。     

Tensile behavior of symmetrical laminates made of PCBA and PMMA layers

The stiffness and strength of a composite material in form of laminate is obtained from the properties of the constituent laminae. The stacking sequence of the laminate affects the mechanical behavior. The interface between different laminae is also an important factor, since it influences the stresses that are developed in the laminate, and hence the strengths. In this study, a theoretical investigation of the mechanical behavior of symmetrical laminates made of isotropic layers [Lexan (PCBA) and Plexiglas (PMMA)] was attempted. An analysis based on the lamination theory was performed to determine the stress distribution and strains as well as the elastic constants. Experimental measurements with specimens made of laminates with different stacking sequences were carried out. The obtained values were compared with the theoretical values given by the lamination theory and mechanics of materials approach. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3215–3226, 2006     

7-（4-氰苯）偶氮-10-羟基苯并喹啉的合成及对F~-的裸眼识别研究

合成了偶氮化合物7-（4-氰苯）偶氮-10-羟基苯并喹啉（主体Ⅰ）,研究了不同阴离子（F-、Cl-、Br-、I-、Ac-、HSO-4）对主体Ⅰ紫外吸收光谱及溶液颜色的影响,并通过1 HNMR滴定实验对识别机理进行了探讨。结果表明,主体Ⅰ可以选择性识别F-：加入适量的F-后,溶液颜色由黄色（主体Ⅰ的颜色）变成了紫红色（主体-F-配合物的颜色）,说明主体Ⅰ能够裸眼识别F-;主体Ⅰ的紫外吸收光谱中生成了新的吸收峰;等吸收点表明主体I与F-是以一定的配比形成了新的配合物;吸收峰的强度与F-浓度在一定范围内呈线性关系。     

对称联苯型环氧树脂的合成

以3,3’,5,5’-四甲基联苯二酚和2-氯乙醇为原料合成3,3'5,5’-四甲基联苯二羟乙基醚,再通过环氧氯丙烷法合成对称联苯型环氧树脂:4,4’-双(2-羟基乙基)-3,3’,5,5’-四甲基联苯二缩水甘油醚(BP1).用傅里叶变换红外光谱和核磁氢谱表征了产物结构,用差示扫描量热法研究了BP1的非等温固化行为,用扫...