Diffusion interaction of vanadium carbide with powdered steels

Conclusions The processes of diffusion interaction of vanadium carbides with cast and powdered steels are largely analogous. Differences are mainly due to unequal diffusional mobility of the components in cast and powdered materials.In cast and powdered steels equal boundary concentration of vanadium are established on the boundary with the carbides, and these concentrations are determined by the carbon content of the steel and by the temperature.The interdiffusion coefficient in ferrite does not depend on the carbon content, and it is the same for cast and powdered steels. The interdiffusion coefficient in austenite increases with increasing carbon content, and it is noticeably larger in powdered steels than in cast steels.The activation energy of interdiffusion in the austenite of powdered steels (220–230 kJ/mole) is noticeably lower than in cast steels (260–270 kJ/mole); this is due to the substantial contribution of the processes of surface diffusion to the overall mass transfer in porous materials.Translated from Poroshkovaya Metallurgiya, No. 11(323), pp. 40–45, November, 1989.     

Peak expiratory flow and the resistance of the mini-wright peak flow meter

The purpose of this study was to examine whether the resistance of the peak flow meter influences its recordings. One hundred and twelve subjects, (healthy nonsmokers and smokers and subjects with lung diseases) performed three or more peak expiratory flow (PEF) manoeuvres through a Fleisch pneumotachograph with and without a mini-Wright peak flow meter added in random order as a resistance in series. The results were as follows. In comparison with a pneumotachograph alone, peak flow measured with an added mini-Wright meter had a smaller within-test variation, defined as the difference between the highest and second highest values of PEF in a series of blows. The mean (SE) variation was 14 (1.3) L.min-1 and 19 (1.5) L.min-1 with and without meter added, respectively. In comparison with the pneumotachograph alone, the addition of the mini-Wright meter caused PEF to be underread, especially at high flows. The difference (PEF with meter minus PEF without meter) = -0.064 (average PEF) -8 L.min-1; R2 = 0.13. The mean difference was -7.8 (1.1) %, and increased numerically for a given PEF, when maximal expiratory flow when 75% forced vital capacity remains to be exhaled (MEF75%FVC) decreased. The reproducibility criteria for repeated measurements of peak flow are more appropriately set at 30 L.min-1 than the commonly used 20 L.min-1, because a within-test variation of less than 30 L.min-1 was achieved in 76% of the subjects without PEF meter inserted and in 88% with meter inserted, with no difference between healthy untrained subjects and patients. The resistance of the peak expiratory flow meter causes less variation in recordings but reduces peak expiratory flow, especially at high values and when the peak is large as compared with the rest of the maximal expiratory flow-volume curve.     

Caroli's disease with intrahepatic gall-stones and salmonella infection

At operation for small bowel intussusception, a 26-year-old man was found to have an enlarged liver and spleen. Subsequent investigations suggested bile passage infection associated with numerous intrahepatic gall-stones but symptomatic cholangitis did not present until 5 months later. Retrograde cholangiography showed cavernous ectasia of the bile ducts which contained gall-stones.     

正构烷烃的氧化以制取合成脂肪酸的研究

试验了国产的各种硬蜡及软蜡,确定了它们的氧化可能性。提出了可供工业上应用的加速氧化反应的二个方法:改善加入催化剂的方法及在泡沫状态下进行氧化。 对於简化分离氧化蜡亦提出了新方案。 文中还叙述了在氧化初期催化剂的作用,对工艺过程的控制有一定的帮助。