Location of methyl branchings in fatty acids: Fatty acids in uropygial secretion of Shanghai Duck by GC-MS of 4,4-dimethyloxazoline derivatives

2-Substituted 4,4-dimethyloxazolines (DMOX) have been found to be a useful alternative to the commonly used methyl esters for the localization of unsaturated bounds and other substituents in the fatty chain by mass spectrometry. The powerful directed fragmentation coupled with good gas chromatographic ability enables the structure elucidation of modified fatty acids in complex mixtures. Continuing our previous study, 76 out of a total of 86 fatty acids obtained from the preen gland wax of shanghai duck now have been identified by gas chromatography-mass spectrometry (GC-MS) of their oxazoline derivatives. The identification was based on the interpretation of the mass spectra and comparison with the spectra and equivalent chain lengths (ECL) of the corresponding methyl esters. Main components of this lipid mixture are straight chain fatty acids (8.22%), and 2-, 4-or 6-monomethyl branched acids (53.69%), amounting to 61.91% of the total acid fraction. In addition, a large number of dimethyl-substituted fatty acids (31.4%) also have been found. Typical mass spectra, which are easily recognizable and highly specific for fatty acids substituted at various positions, are presented and classified according to the structural feature of the chain. Chemical Modification in Mass Spectrometry 6. For preceding paper in this series, see Ref. 17.     

呕吐毒素生物脱毒研究进展

脱氧雪腐镰刀菌烯醇（DON）又名呕吐毒素（VT）,是镰刀菌属（Fusarium spp.）产生的最常见的真菌毒素之一,广泛存在于谷物及其相关制品中,给世界粮食生产造成巨大经济损失,也给人类和动物健康带来重大威胁。目前,利用微生物和酶对DON进行生物脱毒的方法展现出良好的应用前景。很多真菌和细菌能够通过自身吸附或降解的方式在DON的脱毒过程中发挥作用。本文概述了食物中DON的发生、毒性作用及DON生物转化机制,对近年来利用真菌、细菌和植物进行DON脱毒以及脱毒材料的应用进行了较为详细的阐述,以期为食品和饲料中DON的生物防控提供参考。     

内网安全数据保密技术分析与比较

内网安全经过多年发展已日渐丰富,包括了身份认证、授权管理、数据保密和监控审计4大领域,论文通过对目前主要的内网安全数据保密关键技术讨论和分析,给出了不同内网安全数据保密技术的优缺点,并对其应用领域进行了讨论。     

腐殖土理化性质的研究

采用扫描电镜、傅立叶红外光谱、电感耦合等离子发射光谱仪等对腐殖土的理化性质进行研究。腐殖土干态下的平均粒径223μm,湿态粒径66.5μm,干腐殖土的密度约为2.47g/cm3,结构疏松多孔。当腐殖土与水充分接触后,其有机质和固体物质仅有微小的溶解。腐殖土与去离子水接触后,钙、镁元素会析出,接触时间小于2h时,析出的钙、镁元素随着接触时间的增加而增加,当接触时间超过2h后,钙、镁元素溶出的量几乎不再增加。腐殖土含有羧基、羟基等官能团,这些都将影响活性污泥的性质。     

盾构施工前向地质探测技术及系统方案设计

将探地雷达应用于直径为6.34 m的法国FCB(Fives Cail Babcock)盾构前向探测中,通过对刀盘进行机械改造以及采用无线和有线联合传输信息的方式,盾尾控制室可实时获取挖掘面前方地质图像。根据各种典型地质类型、障碍物及其相应的雷达图像建立盾构前向探测分析系统,通过分析当前施工地质的雷达图像,实现对挖掘面前方地质状况的解释和识别,为安全准确地进行盾构施工提供依据。理论分析和试验表明,利用该前向探测技术实现地质的超前探测是完全可行的,具有一定的创新性和工程应用价值。     

Composite substrate LiGaO2 (0 0 1)β-Ga2O3 (1 0 0) fabricated by vapor transport equilibration

Highly (0 0 1) orientation LiGaO₂ layers have been successfully fabricated on (1 0 0) β-Ga₂O₃ surface by vapor transport equilibration (VTE) technique. The temperature is very important for the VTE treatment. At low temperature (800 °C), LiGaO₂layers are textured. As the temperature was raised to 1100 °C the layer becomes highly oriented in the [1 0 0] direction. It shows that the best temperature for VTE treatment is 1100 °C. This technique is promising to fabricate small lattice mismatch composite substrate of LiGaO₂ (0 0 1)β-Ga₂O₃ (100) for GaN films.     

Structural Design Study for ITER Upper ELM Coils

ITER ELM coils are important parts of in-vessel coils and they are mounted on the vacuum vessel and behind the blanket module. They consist of three sets of coils, referred to as the upper, mid, and lower coils. In order to verify the structural design feasibility and find the better structure for upper edge localized modes (ELM) coil, two different variants of coil support structures are studied under the electromagnetic load, thermal and other loads. Results show that besides the bracket of variant 2 does not meet the fatigue criteria, the conductor, jacket and bracket of the two structures can meet the static, fatigue and crack threshold criteria and both of them are valid and feasible. In addition, the better structure is chosen for upper ELM coil.     

Structural and Fracture Mechanics Analysis for the Bracket of ITER Upper ELM Coil

The brackets are the important components of ITER edge localized modes (ELM) coils to connect the coils and rails. In order to assure the structural integrity and security of the bracket, the maximum tresca stress and stress intensity factor are examined from the viewpoints of structural and fracture mechanics. Based on the finite element method, the global upper ELM coils with simplified and detailed bracket are investigated. Since it is difficult to perform in-service inspection due to inaccessibility of in-vessel coils, it is important to estimate the allowable initial defect. Assuming an initial crack in the maximum first principal stress region on the bracket, the fracture mechanics analyses under different loads are performed. Results show that the bracket design is valid and feasible and the calculation method of finite element for stress intensity factor is feasible and reliable. Assuming the initial crack of 7 mm depth, the bracket can meet the crack growth criteria. The stress intensity factor of the bracket is mainly caused by electromagnetic (EM) load and the thermal load can reduce the stress intensity factor under EM load. The thermal load can make the crack grow on the surface of the bracket and the EM load can cause the crack to extend in the inner of the bracket.     

Mechanical Analysis for ITER Lower CC Feeder

ITER correction coils (CCs) feeder is the important component of ITER feeder systems to supply the cryogens and electrical power for CCs. They should withstand the huge electromagnetic (EM) force and high thermal shrinkage. Considering the EM and thermal loads, mechanical analysis is performed to qualify the structural strength of the lower CC feeder. Results show that containment duct and cryopipe can meet the static criteria but busbar jacket cannot meet. It is proposed that more supports should be added at the corners for the busbar. Basically, the lower CC feeder design is valid and feasible.