„Memory effect” of single germanium crystals in photoepitaxy

The Science of Nature -     

Papierchromatographische Untersuchung von Thyroxin und anderen Jodthyroninen

The Science of Nature -     

Is maternal alpha-fetoprotein screening still of value in a low-risk area for neural tube defects?

Estimation of maternal serum alpha-fetoprotein (AFP) was used as a screening method for the detection of neural tube defects (NTDs) in 6344 women over three years. Of 88 (1.4 per cent) who had one or more serum AFP levels equal to, or greater than, 2.5 multiples of the median (MoM) for the relevant gestational age, 43 (0.68 per cent) underwent amniocentesis. There were eight NTDs. Four of these were screened by serum AFP, and all cases of spina bifida had serum AFP levels greater than 3.0 MoM, including one small open defect which was not seen on ultrasound. The other four cases of NTD, which were not screened, were identified by ultrasound. Of 64 singleton pregnancies 32 (50 per cent) had serum AFP levels between 2.5 and 3.0 MoM, and low birthweight (⪕2500 g) occurred in 29 per cent. Because of improvements in ultrasound techniques and the apparent falling incidence of NTD, the role of serum AFP as the primary screening procedure should be regularly reviewed. Effective screening is dependent on mothers booking early.     

Effect of leachate recycling and inoculation on the biochemical characteristics of municipal refuse in landfill bioreactors

Activity development of key groups of enzymes involved in municipal refuse decomposition was measured in laboratory landfill bioreactors with and without leachate recycling and inoculation for about 210 days.The results showed that the enzymes(amylase,protease,cellulase,lipase and pectinase)were present in fresh refuse but at low values and positively affected by leachate recycling and refuse inoculation.The total average of cellulase activity in digesters D3 operated with leachate recycling but no inoculation,D4 and D5 operated with leachate recyling and inoculation was much higher than that in digesters D1 and D2 without leachate recycling and inoculation by 88%-127%,117%-162%and 64%-98%.The total average of protease activity was higher in digester D4 than that in digesters D1,D2,D3and D5 by 63%,39%,24%and 24%,respectively,and the positive effect of leachate recycling and inoculation on protease activity of landfilled refuse mainly was at the first two months.The total average of amylase activity was higher in digesters D3,D4 and D5 than that in digesters D1 and D2 by 83%-132%,96%-148%and 81%-129%.During the early phase of incubation,the stimulatory effect of inoculation on lipase activity was measured,but refuse moisture was the main factor affecting lipase activity of landfilled refuse.The inoculation,initial and continuous inoculation of microorganisms existing in leachate,was the mainly stimulatory factor affecting pectinase activity of landfilled refuse.     

低中放废物处置场核素经地下水迁移对环境影响预测

研究了我国某民用低中放固体废物处置场核素迁移的途径，对核素在地下水中的迁移进行了详细分析与计算，假定正常释放或一次降水量达到６００ｍｍ，处置场底浸泡一个月，存在６ｍ的包气带时，对该处置场处置的７种核素进行预测，结果表明，包气带是延迟核素迁移的主要屏障，在５００年内，可以使＾６０Ｃｏ＾１３７Ｃｓ＾９０Ｓｒ、＾６３Ｎｉ等核素延迟，其中＾２３９Ｐｕ降低６个月数量级，但不能延迟＾３Ｈ和＾１４Ｃ的迁移，穿过