Microstructure and mechanical properties of liquid phase sintered silicon carbide composites

Silicon carbide (SiC) composites were prepared by hot-press sintering from α-SiC starting powders with BaAl2Si2O8 (BAS). The effects of additives on densification, microstructure, flexural strength, and fracture behavior of the liquid phase sintered (LPS) SiC composites were investigated. The results show that the served BAS effectively promotes the densification of SiC composites. The flexural strength and fracture toughness of the SiC composites can reach a maximum value of 454 MPa and 5.1 MPa·m1/2, respectively, for 40% (w/w) BAS/SiC composites. SiC grain pullout, crack deflection, and crack bridging were main toughening mechanisms for the sintered composites.     

LPS刺激对鸡HD11细胞RIPK2基因甲基化的影响及调控

为分析LPS刺激前后对RIPK2基因甲基化的影响,试验采用凝胶电泳、亚硫酸氢盐、双荧光素酶报告系统和qRT-PCR方法分析LPS刺激前后RIPK2基因的甲基化模式及甲基化相关试剂对鸡RIPK2启动子活性及表达水平影响。结果表明：LPS刺激后鸡RIPK2基因甲基化水平从53.8%下降至15.4%;5-氮杂胞苷显著性提高鸡RIPK2启动子活性,促进基因表达;而CpG甲基转移酶M. SssI显著性抑制鸡RIPK2启动子活性,抑制基因表达。研究结果对提高家禽免疫和控制过度性炎症反应具有十分重要的现实意义。     

伤寒免疫学诊断方法的研究现状

对近年伤寒免疫学诊断方法结合作者的研究工作进行了评价。伤寒免疫学诊断可分检测早期病人体液中抗原及测定患者血清中抗体两个方面。检测抗原以SPA-CoA与ELISA(包括Dot-ELISA)较为敏感和特异,而DRLAT则有简便的优点。测定抗体以PHA最为简便与快速。使用LPS-PHA可作伤寒的早期快速诊断,而Vi-PHA可作伤寒病后带菌者的初筛。ELISA有较PHA更高的敏感性,其中LPS-IgM-ELISA亦可作伤寒病人的早期诊断,而LPS-IgG-ELISA可用于该病的追溯诊断和血清流行病学调查。Vi-ELISA还可作伤寒病后带菌者初筛。不同条件实验室可根据取得试剂情况选择使用。     

Validity of an ultra-wideband local positioning system to measure locomotion in indoor sports

The validity of an Ultra-wideband (UWB) positioning system was investigated during linear and change-of-direction (COD) running drills. Six recreationally-active men performed ten repetitions of four activities (walking, jogging, maximal acceleration, and 45º COD) on an indoor court. Activities were repeated twice, in the centre of the court and on the side. Participants wore a receiver tag (Clearsky T6, Catapult Sports) and two reflective markers placed on the tag to allow for comparisons with the criterion system (Vicon). Distance, mean and peak velocity, acceleration, and deceleration were assessed. Validity was assessed via percentage least-square means difference (Clearsky-Vicon) with 90% confidence interval and magnitude-based inference; typical error was expressed as within-subject standard deviation. The mean differences for distance, mean/peak speed, and mean/peak accelerations in the linear drills were in the range of 0.2–12%, with typical errors between 1.2 and 9.3%. Mean and peak deceleration had larger differences and errors between systems. In the COD drill, moderate-to-large differences were detected for the activity performed in the centre of the court, increasing to large/very large on the side. When filtered and smoothed following a similar process, the UWB-based positioning system had acceptable validity, compared to Vicon, to assess movements representative of indoor sports.