Winkler地基模型上功能梯度材料涂层的摩擦接触问题

研究Winker地基模型上功能梯度材料涂层在一刚性圆柱形冲头作用下的摩擦接触问题。功能梯度材料涂层表面作用有法线向和切线向集中作用力。假设材料非均匀参数呈指数形式变化,泊松比为常量,利用Fourier积分变换技术将求解模型的接触问题转化为奇异积分方程组,再利用切比雪夫多项式对所得奇异积分方程组进行数值求解。最后,给出了功能梯度材料非均匀参数、摩擦系数、Winker地基模型刚度系数及冲头曲率半径对接触应力分布和接触区宽度的影响情况。     

延胡索酸泰妙菌素在乙炔黑-离子液体复合修饰玻碳电极上的电化学行为及电分析方法

用乙炔黑(Acetylene black,AB)和离子液体(Ionic liquid,IL)制备了乙炔黑-离子液体复合修饰玻碳电极(AB-ILs/GCE),并用电化学阻抗谱(EIS)进行了表征。采用循环伏安法(Cyclic voltammetry,CV)和计时电流法(Chronoamperometry,CA),方波伏安法(Square wave voltammetry,SWV)研究了延胡索酸泰妙菌素(TF)在此电极上电化学行为及电化学动力学性质。结果表明,TF在玻碳电极(GCE)上于0.74 V处出现一个不可逆氧化峰,与GCE相比TF在AB/GCE上的氧化峰电位基本不变,氧化峰电流增大1.8倍;而与AB/GCE相比,TF在AB-ILs/GCE上的氧化峰电位略有负移,氧化峰电流增大3倍。实验结果表明,AB-ILs/GCE对TF电化学氧化有明显的催化作用。同时考察了实验条件对TF电化学行为的影响,测定了电极反应过程动力学参数,并用本方法对TF针剂中TF含量进行了定量测定,RSD在1.1%～2.9%之间,加标回收率在98.6%～101.8%之间。据此建立了TF电化学定量测定方法。     

市售蘑菇中微量元素测定分析

采用原子吸收分光光度法测定了银川市大型超市里10种新鲜蘑菇中的锰、铁、锌和铜含量。各元素测定方法的变异系数为1.9%~4.2%,回收率在92.1%~104.0%之间。结果表明,锰、铁、锌和铜在蘑菇中含量的分布分别为6.75%~23.64%,80.37%~233.40%,28.00%~118.7%,2.55%~40.69%。测定结果对评价市售蘑菇微量元素营养价值具有参考意义。     

Some thoughts on future research into hand-arm vibration studies

Vibration is an omnipotent force, which has moulded our lives one way or another. Human race has harmoniously adapted to this soothing, caring and benevolent force over many millions of years. Today, this very life-sustaining force has been transformed into a monster force, significantly affecting the health and safety of innocent souls all over the world! A wealth of information exists in the published literature, revealing the various aspects of vibration environment on human activities.Many industrial nations have formulated standardized procedures to safeguard the wellbeing of their working populations, by preventing vibration pollution levels reaching various parts of the body by various means. There are still significant areas of inquiry where fresh approaches can be made to broaden our basic understanding of many mechanisms involved and to offer positive solutions to the vibration-polluted community.     

Synthesis of substituted-amidine derivatives of avibactam and synergistic antibacterial activity with meropenem

New avibactam derivatives in which amide moiety is replaced by substituted amidine groupings were obtained in several steps, the key step having involved the conversion of 2-positioned cyano group of the 1,6-diazabicyclo[3.2.1]-octane framework into the amidine one. Synergistic antibacterial activity of the new compounds in combination with meropenem infers the agonistic effect of these derivatives against β-lactamases.     

The dynamics of RNA participation in the vitellogenesis of Rhipicephalus sanguineus ticks Latreille 1806 (Acari:Ixodidae). I. Nucleoli or Cajal bodies?

To understand the morphological and histological aspects of internal systems of ticks has become important matter since these arthropods have an impact in the areas of the economy and public health. In this context, this study has provided morphological data on female germinative cells of Rhipicephalus sanguineus ticks, ectoparasites of dogs that maintain a close relationship with human on a daily basis. Oocytes of engorged females were analyzed, through the PAS reaction (detection of polysaccharides) counterstained by methyl green (detection of RNA) revealing information that allowed to infer for the first time the presence of Cajal bodies, in the germinal vesicles (nuclei) of developing oocytes, as well as showing how the RNA and the polysaccharides are involved in the dynamics of the vitellogenesis in this species.