Operating in Tandem Chinese experts in Sao Tome and Principe cooperate with local farmers to raise medical standards in the breeding industry

Santomean pig farmer Simao Vicente was hopeful when he came to ask Zou Rui for help. His pig was suffering from hernia, and Zou, a 42-year-old Chinese agricultural expert working in Sao Tomé and Príncipe, was the only person on the island who could provide emergency surgery.

Flow characteristics at low Reynolds number around two in-line circular cylinders with slits

This study investigated numerically the characteristics of laminar flow around two identical circular cylinders placed in tandem, with slits of the same width through their respective axis. The center to center distance between the cylinders and the slit orientation were varied to study their effects on the flow structure, lift and drag, and vortex shedding characteristics. It was found that three flow regimes could be distinguished, the transitions between which could be indicated by the sudden changes in drag and lift. Asymmetrically, configured slits destabilized the stagnant region between cylinders;whereas in-line slits connect the two cylinders to act as a single elongated bluff body, even at large cylinder separation, by stabilizing the stagnant region in between. These in turn strongly modified the transition between flow regimes. Vortex shedding was also strongly influenced by both slit configuration and cylinder separation.

Study of Energy Resolved Mass Spectraof DNT Isomers

Energy raolved mass spectra (ERMS) of 2, 3-DNT and 3, 5-DNT isomers was mported. The fragmentation of this pair of DNTisomers was studied by ERMS in electron impact (EI),and their breakdown curves were discussed , These nitraromaic isomers can be characterized according to the differences between their ERMS in MS/MS

气相色谱-串联质谱法同时检测生活饮用水中8种N-亚硝胺

目的建立同时测定生活饮用水中8种N-亚硝胺类化合物的气相色谱-串联质谱检测方法。方法取1.0 L水样,加入20 g氯化钠,2.0 g碳酸氢钠,调节水样pH值后,以5.0 ml/min^10.0 ml/min流速过椰壳活性炭固相萃取柱富集、二氯甲烷洗脱收集后,以D6-N-亚硝基二甲胺和D14-N-亚硝基-二正丙基亚硝胺为内标,采用Agilent VF-WAXms (30 m×250μm,1μm)色谱柱分离,气相色谱-串联质谱仪检测。结果在5 ng/L^400 ng/L内,方法线性关系良好(r> 0.999),最低检出限为0.65 ng/L^7.81 ng/L,定量限为2.15 ng/L^26.04 ng/L;在加标水平为10.0 ng/L,50.0 ng/L时,平均回收率为68.72%~125.39%,相对标准偏差为2.64%~13.45%。结论该方法快速、灵敏、准确度高,适用于饮用水中N-亚硝胺类化合物的测定。