土壤中嗪草酮迁移和降解的研究

 通过两季马铃薯大田试验，研究了嗪草酮在灌溉沙壤土中的消失和移动情况。结果表明，表层土壤中，嗪草酮施用后最初7～15天内其含量急剧降低，此后随时间推移降低幅度平缓，1993年和1994年试验结束时的残留量分别为5.9μg/kg和2.3μg/kg。两年共采集的379个土样（分布在15～75cm各土层）中只有5个检测到有嗪草酮。1994年大田135cm土层处的水样中，嗪草酮的检测率高达66％，检测浓度范围为0.06～15.85μg/kg，平均浓度为1.94μg/kg。相比较，嗪草酮在大田试验中的消失速率远大于实验室控制条件下的降解速率。     

Prenatal diagnosis of GM2-gangliosidosis B1 variant

Prenatal diagnosis in a pregnancy at risk for a juvenile B1 variant of GM₂-gangliosidosis was carried out. The biochemical study of the cultured amniocytes and the affected fetal brain is reported. The results obtained show that the sulphated artificial substrate can be used in the diagnosis of B1 variant, but not the neutral one. The accumulation of GM₂-ganglioside in the fetal brain of the B1 juvenile form and an infantile form of GM₂-gangliosidosis (0 variant) was compared.     

Chorionic villus sampling—short-term versus long-term culture in a subtle 2; 18 translocation

Prenatal diagnosis on chorionic villous tissue was performed for a woman with the karyotype 46,XX,t(2;18)(q32;q12)—a subtle ‘difficult’ translocation. The case illustrates the necessity of good quality cytogenetics for accurate prenatal diagnosis. For chorionic villi this can be obtained only with long-term culture.     

Serum PAPP-A measurements in first-trimester screening for Down syndrome

Serum PAPP-A measurements taken from 254 women in the first trimester are reported. Eleven chromosomal abnormalities were detected. The mean serum PAPP-A levels in cases of Down syndrome were 0.44 MOM at 9 weeks gestation, 0.15 MOM at 10 weeks, and 0.29 MOM at 11 weeks. The PAPP-A level at 10 weeks was below those of pregnancies which aborted spontaneously. At 11 weeks, the pregnancies with Down syndrome recorded the lowest PAPP-A levels at that gestation. On this small sample, offering chorionic villus sampling to women with singleton pregnancies and a PAPP-A level below 0.3 MOM (approximately 6.5 per cent of this at-risk group) would have detected all the Down syndrome fetuses at 10 weeks and 50 per cent at 11 weeks without selecting those cases destined to abort. This suggests that serum PAPP-A should continue to be investigated as a potential first-trimester screening test for Down syndrome.     

Gas chromatographic separation and determination of chloroanthracene isomers on fly ash

An efficient, reproducible and rapid fused silica capillary column gas chromatographic method, in splitless mode, for analysing of the three chloroanthracene isomers is described. The method affords efficient separation and good linearity for each isomer in the range of 0.2 -200 μg/ml. The method can also be used in separation and determination of another thirty three aromatic and their halosubstituted compounds. This paper also presents the applications of the method in analysing of complex products mixture from reaction of the selected aromatic compounds with hydrogen chloride on fly ash surface from municipal incinerator.