Thermal oxidation and nitridation of sputtered Zr thin film on Si via N2O gas

Formation of ZrO₂ by simultaneous thermal oxidation and nitridation in nitrous oxide of sputtered Zr on Si substrate is reported here for the first time. Sputtered Zr on Si substrate and followed by oxidation and nitridation in nitrous oxide ambient at 700 °C for various durations (5-20 min) have been systematically investigated. The structural and chemical properties of the samples were examined. Chemical depth profiles of the samples have been evaluated by X-ray photoelectron spectroscopy. Stoichiometric Zr-O (ZrO₂) and its interfacial layer consisted of mixed sub-stoichiometric Zr-O, Zr-N, Zr-Si-O, Si-N, and/or Si-O-N phases were identified. A possible model related to the oxidation and nitridation mechanisms has been proposed and explained. Supportive results related to the model were obtained by energy filtered transmission electron microscopy, X-ray diffraction, Raman spectroscopy and Fourier Transform infrared analysis.     

Review on oxides of antimony nanoparticles: synthesis,properties, and applications

In this article, synthesis methods, properties, and applications of antimony oxide nanoparticles are reviewed. Oxides of antimony exist in three phases, namely antimony trioxide, antimony tetroxide, and antimony pentoxide. Physical and optical properties of these nanoparticles are reviewed and compared with their bulk forms. According to literature works, a total of eight synthesis methods have been used to produce these nanoparticles. The size, distribution, shape, and structure of the nanoparticles which are synthesized by different methods are compiled and compared. It is reported that the properties are strongly dependent on the synthesis methods. Advantages and disadvantages of each synthesis method are discussed and compared. Most literatures report on the optical and physical properties of the nanoparticles. Reports on the electrical properties are scarce. As the applications of these nanoparticles cover a wide range, several challenges must be overcome to use them well. These challenges are also being presented and explained in this article.     

质子交换膜燃料电池建模及其PID控制

针对目前质子交换膜燃料电池(PEMFC)模型难以适用于控制系统的设计,提出利用Matlab-Simulink仿真工具对PEMFC进行系统动态模型建立,并在此基础上采用比例积分微分(PID)算法控制其输出电压.仿真结果表明该模型较好地反映出PEMFC系统的动态特性,有助于改善PEMFC的设计,提高其性能,而且PID算法能够较好地实现对PEMFC系统的控制,可适用于控制系统的设计.     

基于改进PSO算法的燃料电池模型优化

采用一种改进粒子群优化(PSO)算法,提出了一种优化燃料电池模型的方法,并用于质子交换膜燃料电池(PEMFC)的极化曲线模型,以得到最优参数.结果表明,这种优化模型的平均平方误差(MSE)为4.42×10-10V2,相关系数为99.87%,数学模型和实验数据之间的拟合精度高.     

The effect of two forms of light on the development of the neonatal rat retina

The effects of red and far red light on the development of the retinas were studied in the neonatal rat models. Red light appeared to be stimulatory and far red light appeared to be inhibitory.     

Studies of L-phenylalanine production by immobilised aminoacylase in stabilized calcium alginate beads

Aminoacylase I (EC 3.5. 1.14) was immobilised by entrapment in uncoated calcium alginate beads and calcium alginate beads coated with chitosan, polyethyleneimine and polyethyleneimine-glutaraldehyde for the production of L-phenylalanine by the hydrolysis of a racemic mixture of N-acetyl-DL-phenylalanine. The operational stability, thermal stability, effects of pH and temperature and kinetic constants, K_m and V_max values of free and immobilised enzymes were studied. Scanning electron micrographs revealed differences in the structures of the surfaces of coated and uncoated beads. Chitosan-coated calcium alginate beads was found to be the best among the immobilised systems studied. The activity and the optimum temperature of immobilised aminoacylase were higher than those of the free enzyme. In addition, the beads showed stable activity under operational conditions. The immobilised aminoacylase lost about 20% of its initial activity after ten cycles of reuse. Polyethyleneimine and polyethyleneimine-glutaraldehyde treatments were also found to enhance the operational stability of the enzyme but its activity was greatly reduced.     

Intestinal and liver changes after chronic ketamine and ketamine plus alcohol treatment

The effects of long‐term chronic ketamine treatment on the intestine and the liver were studied in the ICR mice which had daily intraperitoneal injection of ketamine at 30mg/kg per day for 7 months. The intestine showed no significant pathology after treatment but had a decrease of the positive sites of proliferative cell nuclear antigen in the mucosae of the intestines after ketamine and ketamine plus alcohol (added in the last month) treatment. No significant apoptosis (via TUNEL) nor necrosis (via lactic acid dehydrogenase) was detected in the intestines of all control and ketamine‐treated groups, with the exception of an increase of lactic acid dehydrogenase in the mucosae of the intestines of the ketamine plus alcohol group. In the liver, loss of glycogen was observed in animals after ketamine and ketamine plus alcohol treatment, in addition to the pathology reported in a previous work. The decrease in quantity of glycogen in the liver reflected either a failure of glycogen synthesis from glucose or an increase of glycogenolysis in the liver. Microsc. Res. Tech. 75:1170–1175, 2012. © 2012 Wiley Periodicals, Inc.     

Immunohistological evidences of Ginkgo biloba extract altering Bax to Bcl-2 expression ratio in the hippocampus and motor cortex of senescence accelerated mice

Ginkgo biloba extract 761 appears to display neuroprotective effect in many nervous diseases and aging. Deterioration of mental functions during aging is always accompanied by loss of neurons, presumably through apoptosis. Here, we studied the effect of G. biloba extract in the expression of Bax/Bcl-2 ratio, an important apoptotic index, in the hippocampus and motor cortex of the aging brain. Bax and Bcl-2 expressions were examined with immunohistochemical methods. Senescence Accelerated Mice Prone Strain 8 was used because the aging process was accelerated with neuropathological alterations similar to those found in the aging human brain. The mice were fed with either G. biloba extract or sucrose from the age of 3 weeks until sacrifice at 3 or 9 months old. In the hippocampus of G. biloba fed 9-month-old mice, the ratio of Bax positive cell to Bcl-2 positive cell (Bax/Bcl-2 expression ratio) was 11.43 +/- 3.11 (mean +/- SD); significantly lower (P < 0.05) than the Bax/Bcl-2 expression ratio of 20.99 +/- 5.34 in the sucrose fed mice. The Bax/Bcl-2 expression cell ratios, however, in the motor cortex were not significantly different between the two groups (2.22 +/- 1.35 versus 2.27 +/- 2.02 for the G. biloba and the sucrose fed mice, respectively). The decrease in the Bax/Bcl-2 expression cell ratio following G. biloba treatment might hence be able to protect the aging hippocampus from moving further down the apoptotic pathway. Western blotting confirmed the decrease of Bax in the brain even after a short term and high dose Ginkgo treatment. It is speculated that the G. biloba extract may be a potential neuroprotective agent against apoptosis through the differential expressions of the Bax and Bcl-2 in the hippocampus.