氧化铝多孔支撑体的制备工艺

叙述了用挤出成型法制备无机膜支撑体的工艺,研究了原料粒径、成孔剂用量和烧结温度对所制得多孔氧化铝支撑体性能的影响。研究结果表明,用粒径小于10μm的-αA l2O3粉体,以7%碳粉为成孔剂,烧结温度为1300℃,可以成功制得孔径分布较窄、平均孔径为2.1μm、孔隙率为48.9%的多通道无机膜支撑体。     

Span-80/NiCl2∙6H2O/甲醇/NaBH4体系高效选择性催化还原α-蒎烯

以斯盘类表面活性剂为稳定剂,以NiCl₂?6H₂O 为催化剂前体,以NaBH₄替代外源易燃易爆的氢气,在室温条件下于“一锅”中实现了α-蒎烯的催化还原。考察了斯盘类型、反应介质、NaBH₄用量及反应时间对于反应的影响,得到适宜的反应条件为：Span-80为稳定剂,甲醇为反应介质,NaBH₄∶α-蒎烯摩尔比为0.5,5%NiCl₂·6H₂O,室温反应5h,α-蒎烯的转化率可高达98%,顺式蒎烷的选择性达99%,催化剂能循环使用3次。使用ICP-AES及TEM研究了循环过程中催化剂的流失及形貌,结果表明：在循环过程中Ni的流失率仅为0.2％;催化剂运行1次后的粒径约为4.2nm且分散均匀,循环3次后部分Ni纳米粒子的粒径因聚集而变大,这也许是造成催化剂活性降低的主要原因。XPS和一系列中毒实验结果表明,催化反应的活性物种在性质上很可能是均相的,而原位生成的纳米镍粒子也许仅作为催化物种的“储库”。与传统α-蒎烯加氢工艺相比,该工艺的特点是安全、温和、操作性强、选择性高。     

碟状α-磷酸锆在聚酯粉末涂料中的防腐蚀作用研究

利用水热法合成了碟状 α-磷酸锆（ α-ZrP）并以此为功能填料制备了新型防腐聚酯粉末涂料,采用 SEM、FT-IR和 XRD对磷酸锆的物理形貌和化,学结构进行了表征,分别运用 TGA-DTG和 SEM分析了防腐涂料涂层的热稳定性与微观形貌。以 3.5%NaCl水溶液模仿海洋环境,测试了不同 α-ZrP含量的聚酯粉末涂层在浸泡过程中的交流阻抗谱（ EIS）和极化曲线（ LSV）分析了 α-ZrP对涂料防腐性能的影响。结果表明：添加碟状 α-ZrP能够大幅增强聚酯涂层的耐腐蚀能力,腐,蚀电压显著正移,腐蚀电流密度下降 1~3个数量级。当 α-ZrP的含量占总组分的 3%时,涂层的防腐性能达到最佳。     

Fuzzy data envelopment analysis: A discrete approach

Data envelopment analysis (DEA) as introduced by Charnes, Cooper, and Rhodes (1978) is a linear programming technique that has widely been used to evaluate the relative efficiency of a set of homogenous decision making units (DMUs). In many real applications, the input-output variables cannot be precisely measured. This is particularly important in assessing efficiency of DMUs using DEA, since the efficiency score of inefficient DMUs are very sensitive to possible data errors. Hence, several approaches have been proposed to deal with imprecise data. Perhaps the most popular fuzzy DEA model is based on α-cut. One drawback of the α-cut approach is that it cannot include all information about uncertainty. This paper aims to introduce an alternative linear programming model that can include some uncertainty information from the intervals within the α-cut approach. We introduce the concept of “local α-level” to develop a multi-objective linear programming to measure the efficiency of DMUs under uncertainty. An example is given to illustrate the use of this method.     

Inhibition of H2O2-induced apoptosis of lymphocytes by calorie restriction during aging

Calorie restriction (CR) is known to delay the aging process in rodents and is postulated to act by decreasing free radical generation and increasing antioxidant enzyme activity. The present study was designed to investigate the effect of CR and age on oxidative stress-induced apoptosis and associated changes in the levels of TNF-alpha, and Bcl-2 in splenic T lymphocytes. Ad libitum (AL)- or CR-fed C57BL/6J mice were sacrificed either at 6 (young) or 18 (old) months and splenic lymphocytes were incubated with or without 25 micro M H2O2 to induce apoptosis. Apoptosis increased with age in cells of AL-fed mice incubated with H2O2. CR prevented this rise in apoptosis in total splenic lymphocytes and in CD4(+) and CD8(+) T lymphocyte subsets either with or without H2O2. Free radicals increased and mitochondrial membrane potential decreased in aged mice. CR prevented these changes and also prevented the age-associated increase in TNF-alpha and loss of Bcl-2 in total splenic lymphocytes and in CD4(+) and CD8(+) lymphocyte subsets. In summary, lymphocytes in aged AL-fed mice were much more susceptible to oxidative stress-induced apoptosis whereas CR normalized apoptosis by preventing the increase in TNF-alpha and the decrease in Bcl-2 associated with aging.     

Estimated daily intake of organochlorine pesticides from dairy products in Brazil

The estimated daily intake (EDI) of organochlorine (OC) pesticides (HCB, α-HCH, lindane, aldrin, p,p′-DDE, p,p′-DDD, and o,p′-DDT) through consumption of dairy products from Rio Grande do Sul State (Brazil) was investigated. Fluid milk and cheese had similar ΣOC levels (26.04 and 26.14 ng g⁻¹ fat, respectively), whereas milk powder had lower levels (2.23 ng g⁻¹ fat). OC levels in UHT milk exhibited a declining trend over time (ΣOC = 27.70 ng g⁻¹ fat in 2000 vs. 1.50 ng g⁻¹ fat in 2009/2010). The EDI of OC pesticides was remarkably higher for children (8.266 ng kg⁻¹ day⁻¹) than for adolescents, adults, and the elderly (ranging from 0.393 ng kg⁻¹ day⁻¹ to 0.614 ng kg⁻¹ day⁻¹). The average EDIs for OC pesticides were below the acceptable daily intakes (ADI), with the exception of aldrin, which greatly exceeded the ADI for children. In addition, some samples (8.8%) exceeded the maximum residue limit for the compounds evaluated.     

α-甲基苯乙烯在生产过程中产生颜色的机理与脱色研究

介绍了α-甲基苯乙烯在加热过程中生产颜色的机理,并用模拟软件设计精馏实验,利用RadFrac模型讨论了回流比与理论板数关系、塔内温度分布曲线的最佳条件,根据精馏原理分离出α-甲基苯乙烯中的有色物质,达到了脱色的目的。     

Research progress on polymer-inorganic thermoelectric nanocomposite materials

A thermoelectric (TE) material is a material where a potential difference is generated as a result of a temperature difference or the corollary of this where a temperature difference is generated when a voltage is applied. These phenomena can be used to generate electricity and/or control temperature. Traditionally, thermoelectric materials are inorganic semiconductors which have been limited in their application by low efficiency and high cost. Since the 1990s, both theoretical and experimental studies have shown that low-dimensional TE materials, such as superlattices and nanowires, can enhance the value of the TE figure of merit (ZT) which is an indicator of TE thermodynamic efficiency. To date it has not been feasible to apply these materials in large-scale energy-conversion processes because of limitations in both their heat transfer efficiency and cost. When compared to inorganic materials, organic conducting polymers possess some unique features, such as low density, low cost, low thermal conductivity, easy synthesis and versatile processability and their use in preparing polymer-inorganic TE nanocomposites appears to have great potential for producing relatively low cost and high-performance TE materials. Recently, an increasing number of studies have reported on polymeric and polymer-inorganic TE nanocomposite materials. The purpose of this paper is to review the research progress on the conducting polymers and their corresponding TE nanocomposites. Its main focus is the TE nanocomposites based on conducting polymers such as polyaniline (PANI), polythiophene (PTH), poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS), as well as other polymers such as polyacetylene (PA), polypyrrole (PPY), polycarbazoles (PC) and polyphenylenevinylene (PPV). Typically, polymer-inorganic TE nanocomposites are produced by physical mixing, solution mixing and in situ polymerization. The key factors that limit the use of these polymers and their polymer-inorganic TE nanocomposites as TE materials are their low ZT values. More recent developments designed to overcome the limitation including, for example, the use of carbon nanotubes and graphenes and the use of computational modelling to accelerate the selection of suitable pairs of conductive polymer and inorganic TE materials to achieve best possible nanocomposites are reviewed.     

The polydispersity of ethylene sequence in metallocene ethylene/α-olefin copolymers III: crystallization and melting behavior of short ethylene sequence

Crystallization and melting behavior of short ethylene sequence of metallocene ethylene/α-olefin copolymer with high comonomer content have been studied by standard DSC and modulated-temperature differential scanning calorimetry (M-TDSC) technique. In addition to high temperature endotherm around 120°C, a low temperature endotherm is observed at lower temperatures (40-80°C), depending on time and temperature of isothermal crystallization. The peak position of the low temperature endotherm T_m^low varies linearly with the logarithm of crystallization time and the slope, D, decreases with increasing crystallization temperature T_c. The T_m^low also depends on the thermal history before the crystallization at T_c, and an extrapolation of T_m^low (30.6°C) to a few seconds has been obtained after two step isothermal crystallization before the crystallization at 30°C. The T_m^low is nearly equal to T_c, and it indicates that the initial crystallization at low temperature is nearly reversible. Direct evidence of conformational entropy change of secondary crystallization has been obtained by using M-TDSC technique. Both the M-TDSC result and the activation energy analysis of temperature dependence suggest that crystal perfection process and conformational entropy decreasing in residual amorphous co-exist during secondary crystallization.     

Influence of precursor solution volume on the properties of spray deposited α-MoO3 thin films

α-MoO₃ thin films were deposited onto a glass substrate with 0.01 M ammonium heptamolybdate tetrahydrate as a precursor salt and deionized water as solvent using spray pyrolysis technique. The influence of precursor solution volume on the structural, morphological, optical and electrical properties were analysed and reported.