基于冗余技术对防爆低压真空馈电开关中智能保护器的改进设计与矿井供电安全

通过对矿用防爆智能化真空馈电开关单片机保护器所存在缺陷的分析,提出利用冗余技术提高其短路保护性能的可靠性,从而提高矿井供电系统的安全性.     

Highly efficient synthesis of(R)-1,3-butanediol via anti-Prelog reduction of 4-hydroxy-2-butanone with absolute stereoselectivity by a newly isolated Pichia kudriavzevii

(R)-1,3-butanediol is an important pharmaceutical intermediate, and the synthesis of(R)-1,3-butanediol using green biological methods has recently been of interest for industrial application. Here, a novel strain QC-1 that efficiently transforms 4-hydroxy-2-butanone to(R)-1,3-butanediol was isolated from soil samples. Based on morphological, physiological, and biochemical tests and 5.8 S-internal transcribed spacer sequencing, the strain was identified as Pichia kudriavzevii QC-1. The reaction conditions were optimized to 35 ℃, pH 8.0, rotation speed 200 rpm, and 6:5 mass ratio of glucose to 4-hydroxy-2-butanone. Evaluation of the effects of 4-hydroxy-2-butanone concentrations on yield and cell survival rate showed that 85.60 g·L~(-1) product accumulated, with an enantiomeric excess of more than 99%, when 30 g·L~(-1)4-hydroxy-2-butanone was added at 0, 10, and 30 h in a 3-L bioreactor. Thus, strain QC-1 showed excellent catalytic activity and stereoselectivity for the synthesis of(R)-1,3-butanediol from 4-hydroxy-2-butanone.     

The Enhancement Effect of Mesoporous Graphene on Actuation of Nafion‐Based IPMC

A facile method to fabricate ionic polymer‐metal composite (IPMC) actuators is proposed. A blend of mesoporous graphene (MG) and Nafion is used as the ionic matrix, which is sandwiched by two layers of blend of reduced graphene oxide (rGO) and Nafion as the electrodes. When subjected to an electrical field of 3 V, the IPMC actuator exhibits a blocking force of 10 gf g^?1 for 20 s, and the same behavior can be repeatedly played for hundreds of cycles. MG improves the mechanical properties of Nafion‐based IPMC, more importantly, the mesopores in graphene provide additional pathway for the diffusion of cationic clusters and thus enhance the actuation speed. In addition, the surface electrodes of rGO protect the interlamellar liquid from evaporation thus ensure the durability.

     

纳米TiO2光催化氧化机理及应用

介绍了纳米ＴｉＯ２光催化氧化有机物的机理及其研究进展和实际应用,并对目前光催化氧化技术发展中存在的问题及今后的研究方向提出一些看法。     

向日葵茎髓提取物的抑菌活性及机制

以向日葵茎髓为原料,制得3种不同极性向日葵茎髓提取物。采用琼脂扩散法测定3种不同极性向日葵茎髓提取物对4种受试菌的抑菌活性;并以其中的金黄色葡萄球菌和大肠杆菌为研究对象,探讨了乙酸乙酯萃取部位(EE)的抑菌机制。结果显示:不同极性萃取部位对4种受试菌均有一定抑制作用。其中,EE处理金黄色葡萄球菌和大肠杆菌的最低抑菌质量浓度(MIC)均为0.78 g/L,半数抑制质量浓度(IC50)分别为(1.11?0.01)和(1.59?0.03)g/L;抑菌作用与其总酚、总黄酮含量呈显著正相关性(P0.05)。通过SEM分析发现,EE处理引起菌体形态变化,破坏菌体的细胞膜结构;EE可增加金黄色葡萄球菌和大肠杆菌细胞膜结构的通透性,使菌体内的电解质、蛋白质、碱性磷酸酶向胞外泄露;应用4?,6-二脒基-2-苯基吲哚(DAPI)染色和荧光检测发现,EE能干扰细菌遗传物质(DNA)的复制,最终抑制受试菌增殖。     

电控LPG点燃式发动机冷起动过程瞬态NO排放特性研究

使用瞬态NO气体分析仪,结合其它发动机参数,研究缸内燃烧过程.试验结果表明NO排放可以成为判断缸内燃烧的新依据.冷起动过程中瞬态NO排放主要集中在初始的几个循环中,而发动机转速稳定后,后续循环瞬态NO排放逐渐降低.冷起动过程中,混合气浓度保持不变时,瞬态NO排放随点火角度的提前而增加.     

利用STAR-CD软件分析2气门直喷式柴油机的螺旋气道

简单叙述2气门直喷式柴油机发展现状，针对2气门直喷式柴油机的螺旋进气道的流场以及压力场等运用STAR-CD软件进行模拟并分析。     

两种透平叶栅流场二次流特性及其涡系结构的可视化实验研究

本文应用 Ｔｉ Ｃｌ４ 烟迹法和表面油膜法对两种透平叶栅二次流特性及其涡系结构进行了流场可视化研究,深入地分析了叶栅端壁及叶栅型面的流动,揭示了叶栅二次流涡系的结构与叶型形状的关系以及马蹄涡吸力面分支和吸力面角涡的发生演变情况。     

高氮量硝化棉的脱硝反应动力学研究(英文)

用实时测定凝聚相分解产物的固体原位反应池/快速扫描傅立叶变换红外光谱热技术研究了高氮量硝化棉(14.14%N)的脱硝反应动力学。该反应的动力学参数(活化能和指前因子)用改良的Coats-Redfern法计算。根据所得结果,提出了在403～465K温度范围内描述高氮量硝化棉脱硝反应的微分动力学方程。     

High-Temperature Oxidation Behavior and Mechanism of a New Type of Wrought Ni–Fe–Cr–Al Superalloy up to 1300°C

The oxidation behavior of a new type of wrought Ni–Fe–Cr–Alsuperalloy has been investigated systematically in the temperature range of1100 to 1300°C. Results are compared with those of alloy 214, Inconel600, and GH 3030. It is shown that the oxidation resistance of the newsuperalloy is excellent and much better than that of the comparisonalloys. Scanning electron microscopy (SEM), electron probe microanalysis(EPMA), and X-ray diffraction (XRD) experiments reveal that the excellentoxidation resistance of the new superalloy is due to the formation of adense, stable and continuous Al₂O₃ and Cr₂O₃ oxide layer at hightemperatures. Differential thermal analysis (DTA) shows that the formationof Cr₂O₃ and Al₂O₃ oxide layers on the new superalloy reaches a maximum at1060 and 1356°C, respectively. The Cr2O3 layer peels off easily, and thesingle dense Al₂O₃ layer remains, giving good oxidation resistance attemperatures higher than 1150°C. In addition, the new superalloypossesses high mechanical strength at high temperatures. On-site testsshowed that the new superalloy has ideal oxidation resistance and can beused at high temperatures up to 1300°C in various oxidizing andcorrosion atmospheres, such as those containing SO₂, CO₂ etc., for longperiods.