有机噻吩分子器件的研究进展

本文对分子电子学器件的发展历程作了简要回顾,着重阐述了基于有机噻吩的分子器件的研究进展,指出了噻吩分子器件研究过程中有待解决的一些问题,希望对噻吩分子器件的研究提供一个有意义的参考。     

Abnormal reoxidation effects in Ba‐excess La‐doped BaTiO3 ceramics prepared by the reduction‐reoxidation method

Ba‐excess La‐doped BaTiO₃ ceramics have been successfully applied to prepare laminated chip thermistor. Ceramics were firstly fired in a high‐purity N₂ flow and then reoxidized in air to obtain positive temperature coefficient of resistivity effect. However, an abnormal reduction trend of room‐temperature (RT) resistivity was found to be always beginning at ~800°C during reoxidation. This anomaly was found closely correlated with the insulating second phase (Ba₂TiO₄) at grain boundary, which destroyed conducting pathways between semiconducting BaTiO₃ grains. When reoxidation temperature was up to ~800°C, the insulating Ba₂TiO₄ could be gradually consumed and then conducting pathways reestablished leading to RT resistivity reduction. To further prove the proposed explanation, the reoxidation effects of TiO₂‐added ceramics were also studied, in which no Ba₂TiO₄ existed and certainly the abnormal RT resistivity reduction disappeared.     

Celastrus orbiculatus Thunb. Decreases Athero-Susceptibility in Lipoproteins and the Aorta of Guinea Pigs Fed High Fat Diet

Celastrus orbiculatus Thunb. (COT), a traditional Chinese herb, has anti-inflammatory and anti-oxidative properties. In this study, we examined the protective effect of COT on the initiation of atherosclerosis induced by high fat diet and explored the underlying mechanisms. We established guinea pig models of hyperlipidemia and treated them with three dosages of COT or 20 mg/kg/d simvastatin (a positive control drug) for 8 weeks. Plasma lipid analysis indicated that COT decreased total cholesterol (TC), non-high-density lipoprotein cholesterol (non-HDL-C), triglyceride (TG), apolipoprotein B100 (apoB100) and apolipoprotein E (apoE) levels and increased high density lipoprotein cholesterol (HDL-C) level. The analysis of the hepatic gene involving cholesterol metabolism by quantitative real-time PCR revealed that COT upregulated the mRNA abundance of LDL receptor (LDL-R), scavenger receptor class B type 1 (SR-B1), cholesterol 7α-hydroxylase A1 (CYP7A1) and the 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR). Oil red O staining showed COT significantly reduced lipid deposition in the arterial wall. Moreover, ELISA assay revealed COT lowered the levels of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in plasma. Meanwhile, the level of Nitric oxide (NO) in plasma was increased by COT. Immunohistochemistry and Western blot analysis showed the expression of CD68 and active NF-kB p65 proteins in the arterial wall was decreased by COT. The content of Malondialdehyde (MDA) and activity of Superoxide dismutase (SOD) in plasma were determined and the data indicated COT suppressed oxidative stress reaction. These results reveal that administration of COT decreases athero-susceptibility through lowering plasma lipid, attenuating inflammation, and suppressing oxidative stress in guinea pig fed high fat diet.     

环氧树脂增韧改性的研究现状

综述了改性环氧树脂的最近研究状况，概述了橡胶粒子、热塑性树脂及热致液晶聚合物等对环氧树脂改性方法。对环氧树脂改性的方向进行了展望。     

关于最大限度提高炼油厂油品收率加工方案研究

分析了炼油厂采用不同工艺路线的加工方案,探讨了最大限度提高炼油厂油品收率的各种有效途径,指出提高油品收率是提升企业经济效益的重要方面。     

Sn-6Bi合金熔体结构转变对凝固组织的影响

通过研究Sn-6Bi合金熔体电阻率随温度的变化规律,发现在不同的温度区间合金发生了两种不同类型的液液结构转变,即高温阶段(890～1095℃)不可逆转变和低温阶段(645℃)的可逆液液结构转变。分析认为可逆的液液结构转变是由四面体结构的Sn-Sn共价键团簇的打破和重聚引起的,而不可逆液液结构转变是由(Bi)n原子集团、亚稳态的Sn原子团簇引起的。根据这一结果进行凝固试验,发现当熔体经历过温度诱导结构转变后会使凝固过冷度增大,凝固时间延长,凝固过程中释放的凝固潜热略微减少,凝固组织明显细化。     

HDPE chelate membranes prepared by preirradiation grafting for adsorption of heavy metal ions

A new chelate membrane was prepared by grafting of glycidyl methacrylate (GMA) onto high‐density polyethylene membranes and subsequent amination of poly‐GMA graft chains. The effects of grafting conditions such as radiation dose and temperature on grafting yield were studied. Effects of various parameters such as grafting yield, pH, and adsorption time on the metal uptake were investigated. The results show that the maximum metal uptake followed as given in the order Cr (III)>Fe (III)>Cu (II)>Cd (II). The metal uptake increased with grafting yield, adsorption time, pH of the medium, and initial concentration. The chelated metal ions are easily desorbed with 0.1 mol/L hydrochloric acid at room temperature. The results obtained from the chelate membrane showed a promising application in extraction of heavy metal ions from industrial effluents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Microstructure and Properties of Micro-Alloyed Mg-2.0Nd-0.2Sr by Heat Treatment and Extrusion

Magnesium (Mg) and its alloys have broad application prospects in the fields such as biomedical materials and automobile manufacturing. A micro-alloyed Mg-2.0Nd-0.2Sr (wt.%) magnesium alloy is designed and obtained through semicontinuous casting. The evolution of microstructures and tensile properties are investigated with different heat treatments and extrusion treatments. The grain sizes decrease significantly after extrusion, thus changing the fracture mode during the tensile testing process. The ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) of the properly processed extrusion alloy (referred to as MNS-E2) reach to 247 MPa, 228 MPa and 24%, respectively. The dramatical improvement of mechanical properties results from the refined grains and interactions between dislocations and precipitates. Some nanoparticle bands blocking the slippage and movement of dislocations are also found in the MNS-E2 alloy. The above causes combined result in an integrated effect of grain boundary strengthening, dislocation strengthening, precipitation strengthening and nanoparticle band strengthening. The contribution of strengthening mechanisms of MNS-E2 alloy consists of grain boundary with around 96 MPa, dislocations with around 3.4 MPa, precipitation strengthening with around 45 MPa and the nanoparticle band with around 18 MPa, respectively.     

钛/钢爆炸复合板界面连接机理与力学行为

本文表征了钛/钢爆炸焊接复合板的界面组织和剪切性能,研究爆炸复合过程的界面结合机理。结果表明,在金属板之间形成了波状界面组织,剧烈塑性变形造成钢基体发生明显的塑性流动,并在界面形成连续的漩涡形貌。TEM和XRD检测证实界面存在纳米尺度的过渡层,并包含有固溶体组织和少量金属间化合物。波状界面组织改善了复合板沿爆炸方向的界面剪切强度,剪切断口显示漩涡组织发生韧性断裂形貌。