A simple flotation and McMaster method (author's transl)

A simple and hygienic flotation and McMaster method is described (cf. Fig. 1): The faeces sample (3-5 gm) is mixed with flotation fluid (40-60 ml) in a disposable plastic cup (cup I) and a circular piece of gauze, with a diameter equivalent to twice the height of the cup plus the diameter of its base, is placed over the cup. By a similar cup (cup II), with the bottom cut off and slits made in the side, the gauze is pressed down in cup I. By this procedure the faeces suspension will be filtered through the gauze and appear in cup II. After 10 minutes some drops after transferred from the surface of the filtrate to a slide by means of a test tube, which is dipped to the bottom of the filtrate and quickly moved over to the slide. The optimal procedure was worked out with faeces containing faeces containing eggs of Ostertagia ostertagi. Saturated sodium chloride with 50 g glucose per 100 ml was found to be a suitable flotation fluid for demonstrating eggs of commonly occurring parasites, e.g., trichostronglyids and ascarids. The described flotation technique is more efficacious than the one hitherto employed. The technique is usable also in connection with a McMaster method: 4 gm. faeces are suspended in 56 ml flotation fluid. Immediately following filtration, filtrate is transferred to a McMaster counting chamber by means of a Pasteur pipette.     

Hydrogen-induced microelectronic capacitor failure in pacemakers

Ceramic chip capacitors used in hybrid microelectronics for cardiac pacemakers are usually highly reliable. However, under certain conditions of capacitor construction, capacitor materials, mounting techniques, and environmental conditions, high failure rates may occur. A specific example is presented in which a ceramic capacitor used in an implanted pacemaker delaminated and failed approximately 30 days after being implanted. The failed capacitor caused a pulse rate rise, but due to circuit design techniques, the rate increase was limited to an acceptable value. The capacitor that failed was from an isolated lot of capacitors that was manufactured using pure palladium plates. The circuit containing this capacitor was hermetically sealed within a titanium case by welding. During the welding, a small amount of hydrogen was released from the titanium which, over a period of 2 to 4 weeks, was absorbed by the palladium plates in the capacitor. By absorbing the hydrogen, the palladium plates exhibit a volumetric expansion of sufficient magnitude to crack and delaminate the capacitor to the point of failure. Subsequently, the recurrence of this failure mode has been avoided by using capacitors containing special palladium alloys that cannot absorb hydrogen. This phenomenon is of interest to pacemaker designers since mercury batteries used in conventional pacemakers generate large amounts of hydrogen and potentially may be responsible for complications when used in conjunction with capacitors containing palladium.     

番茄红素菌体粉的安全毒理学评价

以三孢布拉氏霉为菌种,对其发酵制备的番茄红素菌体粉的经口急性毒性、遗传毒性及短期毒性等进行了研究。结果表明:番茄红素菌体粉经口最大耐受量(MTD)大于18g·kg-1,毒性分级为无毒级;Ames实验、小鼠骨髓细胞染色体畸变实验、小鼠精子畸形实验均表明番茄红素菌体粉无明显遗传毒性;30d短期喂养各组小鼠无异常症状,无死亡,其对小鼠的体重增长、血常规、血生化、脏器系数均无显著的影响。揭示了番茄红素菌体粉有较好的安全性,为番茄红素菌体粉直接应用成保健食品等提供理论依据。     

无锡某SOHO办公楼水源热泵VRV空调系统设计及分析

对某办公楼空调系统的设计做了多方案比选,最终确定为水源热泵VRV系统方案。对水源热泵VRV系统的设备做了设计选型,对水源热泵VRV的建设模式、节能运行做了讨论,为地产开发商、设计咨询公司、施工企业等提供参考。