Trisomy 16 detected at chorion villus sampling

Trisomy 16 detected at chorion villus sampling (CVS) may reflect the placental but not the fetal karyotype. We describe a case in which the pregnancy continued until intrauterine death at 37 weeks. Cytogenetic study of two placental samples showed 47, +16 and 46,XX; the fetus was morphologically grossly normal, but fetal tissue culture was unsuccessful. Conservative management may be appropriate when trisomy 16 is detected at CVS and the pregnancy is normal ultransonographically.     

Prenatal detection of trisomy 9 mosaicism

Chromosomal mosaicism in amniotic fluid cells poses a serious dilemma in prenatal diagnosis since the observation may represent: (1) pseudomosaicism—an inconsequential tissue culture artefact; or (2) true mosaicism—occurring in approximately 0.0 per cent of amniocenteses with a significant impact on pregnancy outcome. Mosaicism for trisomy 9 was observed in an amniotic fluid specimen obtained for advanced maternal age with two cell lines [46,XX (46 per cent)/47,XX, + 9 (54 per cent)] present in each of four culture flasks. Since more than 75 per cent of newborns with trisomy 9 mosaicism have complex cardiac malformations, a fetal echocardiogram was obtained at 20 weeks' gestation and interpreted as normal. A fetal blood sample (22 weeks' gestation) disclosed only a single trisomy 9 cell among the 100 metaphases analysed. However, a second fetal echocardiogram performed at the time of blood sampling suggested a non-specific cardiac anomaly. Fetal autopsy following elective pregnancy termination revealed several malformations including severe micrognathia, persistence of the left superior vena cava, and skeletal anomalies. Cytogenetic studies of cell cultures derived from several fetal tissues demonstrated trisomy 9 ranging from 12 to 24 per cent.     

Relationships of ozone formation sensitivity with precursors emissions, meteorology and land use types, in Guangdong-Hong Kong-Macao Greater Bay Area, China

Due to the influences of precursors emissions, meteorology, geography and other factors, ozone formation sensitivity(OFS) is generally spatially and temporally heterogeneous. This study characterized detailed spatial and temporal variations of OFS in Guangdong-Hong Kong-Macao Greater Bay Area(GBA) from 2012 to 2016 based on OMI satellite data, and analyzed the relationships of OFS with precursors emissions, meteorology and land use types(LUTs). From 2012 to 2016, the OFS tended to be NO x-limite...     

基于20 L球罐的多相混合物扩散模拟

为更好地探索多相混合物的爆炸特性，以铝粉、乙醚、空气为研究对象，基于20 L球型爆炸罐建立三维计算模型，对气固两相和气液固三相混合物的分散过程进行数值模拟，以分析不同多相混合物分散过程的差异，并为测量多相混合物爆炸下限时的点火延迟时间设定提供参考。监测分析铝粉浓度粒子分布、流场内部湍流动能以及液相体积百分数等的演化过程，讨论混合物分散效果的差异，并确定测量爆炸下限的点火延迟时间。研究结果表明:实验工况下，液相的存在会降低粉尘云团的湍流动能、降低其扩散速度，并使粉尘云内部浓度更均匀。测量多相混合物爆炸下限时，三相混合物的最佳点火延迟时间早于气固两相混合物10~20 ms。     

对20世纪中国洪灾的回顾

回顾了20世纪中国的洪灾，对20世纪80年代后洪涝灾害愈演愈烈的原因进行了探讨。     

Synthesis,separation and structure determination of 2,3,3'‐trichlorobiphenyl (PCB 20)† and 3,3’,4‐trichlorobiphenyl (PCB35)†

The combined synthesis and spectrometric characterization of 2,3,3'‐trichlorobiphenyl (PCB 20) and 3,3’,4‐trichlorobiphenyl (PCB 35) is described for the first time. By a combination of highly efficient column distillation and repeated recrystallizations it was possible to isolate the two products as reference materials with a purity exceeding 99%. X‐ray analysis of crystals of 2,3,3'‐trichlorobiphenyl positively identified the substitution pattern of the biphenyl moiety by chlorine atoms. The two phenyl rings are at an angle of 52°, while the relative disposition of the chlorine atoms on both rings is closer to anti than to syn.     

桑色素-吐温-20胶束增溶分光光度法测定微量铁

本文对铁（Ⅲ）与桑色素（Ｍｏｒｉｎ）的显色反应进行了研究。在非离子表面活性剂吐温－２０存在下,于ｐＨ４．１的邻苯二甲酸氢钾缓冲溶液中,铁（Ⅲ）与桑色素形成稳定的黄色配合物,其组成比为Ｆｅ（Ⅲ）∶Ｍｏｒｉｎ＝１∶３,最大吸收波长为４１８ｎｍ,表观摩尔吸光系数为６．６９×１０４Ｌ／ｍｏｌ·ｃｍ,铁（Ⅲ）浓度在０～１６μｇ／２５ｍｌ范围内符合比耳定律。方法简便、快速,选择性好。应用于环境水样和植物中微量铁的测定,结果满意。     

The significance of trisomy 7 mosaicism in chorionic villus cultures

Two cases of mosaic trisomy 7 confined to the cultured cells and not found in direct preparation were detected from 200 consecutive first-trimester chorionic villus samples (CVS) analysed. The mosaicism was similar in the two cases, but the pregnancy outcome was different. In both cases, the direct metaphases from the CVS were 46, XY. Culture metaphases were mos46,XY/47,XY, + 7; the trisomy 7 was seen in 34 per cent of cells from case 1 and 53 per cent from case 2. A sonogram at 15¹/₂ weeks revealed fetal death in utero in case 1, and the patient declined amniocentesis. The fetal tissue failed to grow in culture, but the placental cultured cells were 47,XY, + 7 in 28 (100 per cent) cells analysed. In the second case, all the amniotic fluid cells were 46,XY and the pregnancy resulted in a normal male with a 46,XY karyotype in the cord blood and foreskin fibroblast cultures. The term placenta was mosaic with 13/163 (8 per cent) trisomy 7 cells. Extensive cytogenetic studies on the placenta for the first time confirmed trisomy 7 mosaicism confined to the villus cultures.