Past changes in the abundance of diatoms as inferred from a sediment core from Hebe Haven, Saikung, Hong Kong

１　Ｉｎｔｒｏｄｕｃｔｉｏｎ１－１　ＤｉａｔｏｍｓＤｉａｔｏｍｓ（ＣｌａｓｓＢａｃｉｌｌａｒｉｏｐｈｙｃｅａｅ）ａｒｅｃｏｍｍｏｎａｎｄｗｉｄｅｌｙｄｉｓｔｒｉｂｕｔｅｄｉｎｂｏｔｈｆｒｅｓｈａｎｄｍａｒｉｎｅｗａｔｅｒｓ（Ｍｏｓｅｒ，１９９６）．ＴｈｅｓｅｍｉｃｒｏｓｃｏｐｉｃｕｎｉｃｅｌｌｕｌａｒｐｌａｎｔｓｆｉｘａｍａｊｏｒｐｏｒｔｉｏｎｏｆｔｈｅＥａｒｔｈ○ｓｃａｒｂｏｎ，ｇｅｎｅｒａｔｅｏｘｙｇｅｎ，ａｎｄｓｕｐｐｌｙｆｏｏｄｔｏａｎｉｍａｌｓｗｈｉｃｈｆｅｅｄｏｎｔｈｅｍ（Ｄｉｘｉｔ…     

Comparison of first-trimester transvaginal amniocentesis with chorionic villus sampling and mid-trimester amniocentesis

Between August 1989 and December 1991, 356 patients underwent first-trimester transvaginal amniocentesis (10–12 weeks). The same number of patients referred in the same period for mid-trimester amniocentesis (14–21 weeks) was matched also for maternal age and indication. A third group consisted of the first 356 cases in which chorionic villus sampling (CVS) was attempted. The overall success rate was 99·7 and 100 per cent for early and mid-trimester amniocentesis, respectively, and 97·2 per cent for CVS. The mean harvesting time was 12·8, 11, and 7·9 days, respectively. The percentage of patients rescheduled was 3·4 per cent in first-trimester amniocentesis, 1·7 per cent in mid-trimester amniocentesis, and 6·2 per cent in the CVS group. The early (less than 2 weeks) pregnancy loss was 1·7 and 0·6 per cent in early and mid-trimester amniocentesis, respectively, and 1·7 per cent in CVS. The total pregnancy loss was 3·2, 0·9, and 2·9 per cent, respectively. The rate of preterm birth was 6·0, 5·2 and 6·9 per cent, respectively. The results indicate that CVS has the shortest procedure-result interval, but the highest rescheduling rate. First-trimester amniocentesis has a higher procedure and laboratory success rate but, until otherwise proved, mid-trimester amniocentesis is the most efficient and safest procedure.     

对《超标环境噪声排污费征收标准》的异议

依据声级测量的误差分析，结合实例，对国家现行《超标环境噪声排污费征收标准》提出异议，建议取消１ｄＢ（Ａ）的超标收费规定、舍弃测量的小数值，并定义一个考虑污染范围的评价量以使收费更加合理。     

Comparison of decolorization of reactive microorganisms isolated from various sources

Azo dyes are among the oldest man-made chemicals and they are still widely used in the textile, printing and the food industries.About 10% - 15% of the total dyes used in the industry is released into the environment during the manufacturing and usage. Some dyes and some of their N-substituted aromatic bio-transformation products are toxic and/or carcinogenic and therefore these dyes are considered to beenvironmental pollutants and health hazards. These azo dyes are degraded by physico-chemical and biological methods. Of these, biological methods are considered to be the most economical and efficient. In this work, attempts were made to degrade these dyes aerobically. Theorganisms which were efficient in degrading the following azo dyes-Red RB, Remazol Red, Remazol Blue, Remazol Violet, Remazol Yellow,Golden Yellow, Remazol Orange, Remazol Black- were isolated from three different sources viz., wastewater treatment plant, paper milleffluent treatment plant and tannery was tewater treatment plant. The efficiency of azo dye degradation by mixed cultures from each source wasanalyzed. It was found that mixed cultures from tannery treatment plant worked efficiently in decolorizing Remazol Red, Remazol Orange,Remazol Blue and Remazol Violet, while mixed cultures from the paper mill effluent worked efficiently in decolorizing Red RB, Golden Yellow and Remazol Yellow. The mixed cultures from wastewater treatment plant efficiently decolorized Remazol Black.     

Some recent advances in the theory of random vibration

A brief introduction is first given of the history of the technical field of random vibration, tracing back to the works of physicists since the beginning of the twentieth century. This is then followed by an account of more recent developments, with emphasis on nonlinear and quasi-nonlinear systems, and on analytical solutions for the associated Fokker-Planck equation and the generalized Pontryagin equation. The governing equation of a quasi-nonlinear system is linear, but with one or more randomly varying coefficients. The techniques for finding exact probability solutions, approximate probability solutions, conditions for motion stability, and the failure probability and statistics of a system are discussed.     

Arbuscular mycorrhizal fungi, rhizobia, available soil P and nodulation of groundnut (Arachis hypogaea) in Zimbabwe

Arbuscular mycorrhizal fungal (AMF) colonization and nodulation of groundnut were examined in nine soils collected from subsistence farmers’ fields in Zimbabwe. Nodule number, shoot dry weight, shoot N and P contents, and AMF colonization were assessed after 6 weeks growth. Both nodule number and AMF colonization differed by an order of magnitude among the nine soils. Soil available P explained almost all the variability in nodule number (r² = 0.98), but had no significant effect on percent AMF colonization. By adding P to one soil, nodule numbers increased four-fold resulting in a significantly higher N content in the shoots. Similar, but smaller, effects were obtained by increasing the abundance of AMF through an inoculation with Glomus intraradices, suggesting that nodulation in this soil was limited by AMF abundance and that the fungi could, to a limited extent, substitute for P fertilizer.     

Microvillar enzyme assays in amniotic fluid and fetal tissues at different stages of development

A systematic study of microvillar enzyme activities in the amniotic fluid in correlation with their values in different fetal tissues during development has been undertaken. Microvillar enzymes appeared in the amniotic fluid at the time of disappearance of the anal membrane, 12–13 weeks, and declined from the 18th week until the 24th week. The study of fetal tissues and fluids has shown that gamma-glutamyltranspeptidase is mainly of liver origin. The significant decrease of the activities of these amniotic fluid enzymes has been the basis of prenatal diagnosis of cystic fibrosis. These assays may be useful for the diagnosis of certain digestive tract abnormalities at later stages of pregnancy.     

Metal removal studied by a laboratory scale immobilized microalgal reactor

１ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｄｕｓｔｒｉａｌｗａｓｔｅｗａｔｅｒｓ，ｐａｒｔｉｃｕｌａｒｌｙｔｈｏｓｅｄｉｓｃｈａｒｇｅｄｆｒｏｍｍａｎｕｆａｃｔｕｒｉｎｇｏｆｐｒｉｎｔｅｄｃｉｒｃｕｉｔｂｏａｒｄ（ＰＣＢ）ａｎｄｅｌｅｃｔｒｏｐｌａｔｉｎｇｃｏｎ...     

Chromosomal abnormalities associated with a single umbilical artery

A single umbilical artery was seen in 10 out of 117 cytogenetically abnormal pregnancies. The abnormal karyotypes found to be associated with a single umbilical artery were trisomy 18 (n = 5), monosomy X (n = 2), triploidy (n = 1), sex chromosome (47,XYY; n = 1) and translocation (46t(X,5)(q13p15); n = 1). With the exception of the translocation case, all cases with a single umbilical artery had anatomical defects which were detectable ultrasonographically. This suggests that a single umbilical artery alone is not an indication for prenatal fetal karyotyping.