Modelling the metabolic action of human and rat CYP1A2 and its relationship with the carcinogenicity of heterocyclic amines

Cytochrome P450 (CYP) is a family of enzymes responsible for organism detoxification. However, some of the members of the CYP1A subfamily also catalyse the activation of heterocyclic amines (HAs), present in cooked meat, to carcinogenic compounds which have been shown to increase the risk of breast, colorectal and lung cancer. In humans, CYP1A2 is the enzyme with the most significant action in HA metabolism but in rodents CYP1A1 is also important in this biotransformation. Understanding the metabolic action of these enzymes is essential to predict the factors that enable the formation of the carcinogenic products. We have built two models of CYP1A2, one for the human enzyme and one for the rat homologue. The templates chosen include the only X-ray structure published to date for a mammal CYP, a quimeric C2A5 from rabbit, as well as CYPs belonging to Bacillus megaterium (CYPBm-3), Pseudomonas putida (CYPcam), Pseudomonas sp. (CYPterp), and Saccharopolyspora erythraea (CYPeryf). Two HAs, MeIQ (2-amino-3,4-dimethylimidazo[4,5-?]quinoline) and MeIQx (2-amino-3,8-dimethylimidazo[4,5-?]quinoxaline), known substrates of human and rat CYPIA2, were docked in the active site of the models, providing information regarding the different catalytic rates associated with the metabolisms in both enzymes. This is important for analysing the behaviour of animal models concerning the testing of anticancer drugs.     

Equivalent properties of single event burnout induced by different sources

The experimental results of single event burnout induced by heavy ions and 252Cf fission fragments in power MOSFET devices have been investigated. It is concluded that the characteristics of single event burnout induced by 252Cf fission fragments is consistent to that in heavy ions. The power MOSFET in the "turn-off" state is more susceptible to single event burnout than it is in the "turn-on" state. The thresholds of the drain-source voltage for single event burnout induced by 173 MeV bromine ions and 252Cf fission fragments are close to each other, and the burnout cross section is sensitive to variation of the drain-source voltage above the threshold of single event burnout. In addition, the current waveforms of single event burnouts induced by different sources are similar. Different power MOSFET devices may have different probabilities for the occurrence of single event burnout.     

Equivalent properties of single event burnout induced by different sources

The experimental results of single event burnout induced by heavy ions and 252Cf fission fragments in power MOSFET devices have been investigated. It is concluded that the characteristics of single event burnout induced by 252Cf fission fragments is consistent to that in heavy ions. The power MOSFET in the ＂turn-off＂ state is more susceptible to single event burnout than it is in the ＂turn-on＂ state. The thresholds of the drain-source voltage for single event burnout induced by 173 MeV bromine ions and ^252Cf fission fragments are close to each other, and the burnout cross section is sensitive to variation of the drain-source voltage above the threshold of single event burnout. In addition, the current waveforms of single event burnouts induced by different sources are similar. Different power MOSFET devices may have different probabilities for the occurrence of single event burnout.     

基于MEMS姿态传感器的声矢量传感器设计

针对声矢量传感器姿态变化难以准确测量导致目标测向精度低的现状,设计一种微型MEMS姿态传感器,并将其封装在声矢量传感器内部,实现基于MEMS姿态传感器的声矢量传感器设计。首先根据声矢量传感器姿态测量与校正原理,采用四元数姿态解算方法及扩展卡尔曼滤波器设计MEMS姿态传感器,并对其进行姿态精度测试;然后基于MEMS姿态传感器进行声矢量传感器样机设计、制作、参数测试;最后对样机进行了海上实验,结果表明,通过姿态校正后声矢量传感器目标方位估计精度与GPS推算方位精度一致,验证了利用MEMS姿态传感器设计声矢量传感器的可行性。     

QuEChERS-液相色谱-串联质谱法测定植物性食品中30种氨基甲酸酯类农药残留

基于欧洲标准化委员会标准方法(EN 15662)对食品基质的分类,选择6种代表性植物性食品作为基质,系统优化了QuEChERS样品前处理方法;在此基础上,建立了30种氨基甲酸酯类农药的液相色谱-串联质谱分析方法。实验结果表明,除涕灭威砜的线性范围为2~100 μg/kg,其他29种氨基甲酸酯类农药的线性范围均为1~100 μg/kg;6种样品基质在3个添加水平(5、20、100 μg/kg)下的回收率为56.13%~127.6%,相对标准偏差为0.47%~16%;以信噪比(S/N)≥10计,30种农药的定量限(LOQ)为0.041~1.9 μg/kg。本文方法灵敏、有效,适用于植物性食品基质中30种氨基甲酸酯类农药残留的测定。     

浅海舰船噪声声强流的垂直方向性

浅海环境中,确定性声源的多途声信号干涉使得接收点处声强流的方向发生改变,不再与声源位置处的声强流方向一致。只测量声场的标量声强时,无法得到接收点处声强流的垂直方向性,而基于简正波矢量场建模和仿真,可获得理想条件下宽带点声源激发声场声强流的垂直方向性。本文采用单矢量水听器进行海上实验,获得了海洋环境噪声和干扰条件下舰船噪声声强流的垂直方向性。仿真和实验结果表明:远场条件下,浅海干涉现象引起接收点处声强流的方向(极角)随频率和距离变化,其时间-频率分布呈现与LOFAR谱干涉条纹相似的条纹,声强流的极角值主要分布在70?～110?范围内。     

加磁场对GZO薄膜结构及光电性能的影响

采用射频磁控溅射法在玻璃基底上制备了Ga掺杂ZnO (GZO)薄膜,在传统磁控溅射系统中引入外加磁场,探究了磁场强度变化对GZO薄膜晶体结构和光电性能的影响.结果表明:所制得的GZO薄膜结构均为六角纤锌结构且在[002]方向沿C轴择优取向;外加磁场强度对薄膜的光电性能具有较大影响,在可见光范围内,薄膜的平均透光率超过93;,并出现了Moss-Burstein效应;薄膜的电学性能得到提升,其电阻率从4.96×10-3 Ω·cm降至3.17×10-4Ω·cm,霍尔迁移率从7.36cm2 ·V-1 ·S-1增至9.53 cm2·V-1·S-1.     

采用可见光源和分划板快速装调激光光路

 分析了激光测量光路的特点和装校要求,给出了采用可见光源、分划板装校激光光路的原理。以预放测量模块为例,介绍了装校的流程及装校中的注意事项,分析了装校所能达到的精度,并用内调焦望远镜进行了装校精度检查。结果表明,采用可见光源、分划板装校的激光光路透镜光轴正过心的偏心极限误差小于等于0.07 mm,光轴倾斜极限误差小于等于25″。     

固相微萃取与高效液相色谱联用技术的进展

 较全面地评述了固相微萃取与高效液相色谱联用技术的发展与应用 ,包括该技术的原理、接口装置、涂层材料等。     

Preparation and Characterization of Zirconia-Magnesia Support Modified by Alkylphosphonic Acid for Liquid Chromatography

Interest in zirconia as a chromatography support has increased considerably recently because of its chemical inertness and its promise as a useful support. We have reported the preparation of spherical zirconia and characterization of its chromatographic behavior. However, the zirconia was found unsatisfactory for its chromatographic efficiency, probably owing to the poor pore structure of it. In this paper, we for the first time report the preparation of alkylphosphonic acid modified zirconia-magnesia stationary phase, and characterization of its structure and chromatographic behavior.