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1.
A simplified method is described for processing both direct preparations and long-term cultures from the same fragment of chorionic villi. Enzyme separation of the outer trophoblast layers (used for direct preparations) from the inner mesenchymal core (used to initiate long-term cultures) facilitates the utilization of the same fragments for the two procedures, without jeopardizing the success of either method. This has proved useful in cases where the sample was so small that only one method of chromosome preparation may have been possible using other techniques. 相似文献
2.
In vitro characteristics of human fetal cells have been investigated after chorionic villus sampling at the first trimester and amniocentesis at the second trimester of pregnancy. Light microscopy revealed heterogeneous morphology of cell types in both the chorionic villus culture and the amniotic fluid cultures. Based on the experiments performed, chorionic villus cells are more sensitive to pronase, trypsin, and versene during subculture and have a higher DNA content per single cell and release more [125I]-Beta-human chorionic gonadotropin into culture medium than those found in amniotic fluid cells. The practical applications of this study are discussed. 相似文献
3.
采用含有二乙二醇(DEG)和乙醇胺(ETA)的双组分解交联剂降解废旧硬质聚氨酯泡沫塑料(PU硬泡),并利用降解得到的低聚物多元醇与木质素复合制备出性能增强的再生PU硬泡。通过对制备的再生PU硬泡的红外光谱、密度、吸水率、抗压强度、热稳定性、导热系数、热重曲线等进行分析测试,考察m(DEG)∶m(ETA)对再生PU硬泡性能的影响。实验结果表明:m(DEG)∶m(ETA)=1∶3时废旧PU硬泡的降解效果最好;木质素加入量为2.0%(w)时再生PU硬泡的密度低、抗压强度高、保温性能良好,达到国家标准《建筑绝热用硬质聚氨酯泡沫塑料》(GB/T 21558—2008)的品质要求。 相似文献
4.
Moe MK Huber S Svenson J Hagenaars A Pabon M Trümper M Berger U Knapen D Herzke D 《Chemosphere》2012,89(7):869-875
For several decades, perfluorooctane sulfonate (PFOS) has widely been used as a fluorinated surfactant in aqueous film forming foams used as hydrocarbon fuel fire extinguishers. Due to concerns regarding its environmental persistence and toxicological effects, PFOS has recently been replaced by novel fluorinated surfactants such as Forafac®1157, developed by the DuPont company. The major component of Forafac®1157 is a 6:2 fluorotelomer sulfonamide alkylbetaine (6:2 FTAB), and a link between the trade name and the exact chemical structure is presented here to the scientific community for the first time. In the present work, the structure of the 6:2 FTAB was elucidated by 1H, 13C and 19F nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. Moreover, its major metabolites from blue mussel (Mytilus edulis) and turbot (Scophthalmus maximus) and its photolytic transformation products were identified. Contrary to what has earlier been observed for PFOS, the 6:2 FTAB was extensively metabolized by blue mussel and turbot exposed to Forafac®1157. The major metabolite was a deacetylated betaine species, from which mono- and di-demethylated metabolites also were formed. Another abundant metabolite was the 6:2 fluorotelomer sulfonamide. In another experiment, Forafac®1157 was subjected to UV-light induced photolysis. The experimental conditions aimed to simulate Arctic conditions and the deacetylated species was again the primary transformation product of 6:2 FTAB. A 6:2 fluorotelomer sulfonamide was also formed along with a non-identified transformation product. The environmental presence of most of the metabolites and transformation products was qualitatively demonstrated by analysis of soil samples taken in close proximity to an airport fire training facility. 相似文献
5.
用蒽醌生产中的废硫酸制备硫酸钾 总被引:2,自引:0,他引:2
研究了以蒽醌生产中的废硫酸为原料,通过缔合,置换,解缔等步骤,制备硫酸钾的最佳工艺条件。在最佳条件下,可使废硫酸中H2SO4的质量分数从23%降至0.60%,废硫酸成盐率为89.01%,硫酸钾纯度为95.85%。 相似文献
6.
董国胜 《安全.健康和环境》2010,10(10):42-44
介绍了电位滴定法、分光光度法、电导法和毛细管电泳法等几种测定物质解离常数的常用方法,分析了其测定原理及优缺点,讨论了解离常数测定方法的研究方向。 相似文献
7.
废弃线路板的粉碎和所含金属组分的高效解离是后续分选回收的前提条件。本研究分别使用乙二胺等10种溶剂浸泡废弃线路板,比较对线路板中铜箔与基板间剥离强度的影响,从而筛选出4种有代表性的溶剂,即溶剂D、溶剂F、丙酮和水, 比较废弃线路板经化学溶胀后的单体解离度和获得一定粒径分布的颗粒所需的破碎时间。研究结果表明,化学溶胀后破碎能大幅提高金属的单体解离度,浸泡效果的优良排序为:溶剂D>溶剂F>丙酮>水;浸泡时间越长,浸泡温度越高,对剥离强度的降低越有利;使用溶剂D在150℃、3 h或140℃、5 h的工艺下浸泡废弃线路板,可以使铜箔与基板自动脱落。研究结果为后续的分选提供了便利的条件。 相似文献
8.
LIU Chun-jiang Hannu Ilvesniemi Werner Kutsch MA Xiang-qing Carl J. Westman Pekka Kauppi 《环境科学学报(英文版)》2004,16(1):86-89
IntroductionCarboncirculatesbetweentheatmosphere ,biosphere ,oceansandthelithosphere(Warneck ,1988) .Thecarbonfluxesbetweenthesereservoirs,suchasburningoffuels ,photosynthesisandrespirationofecosystems,andtheuptakeoftheocean ,havebeenestimatedquantitative… 相似文献
9.
酚类污染物解离态与非解离态光解特性及其速率常数的预测 总被引:3,自引:2,他引:1
以氙灯为光源模拟太阳光,通过研究不同pH条件下3种酚类污染物直接光解的过程,探讨了酚类污染物的解离对其光解规律的影响,并建立了解离态与非解离态酚类污染物光解速率常数的计算方法及预测模式.结果表明,随着pH从4.0增加到9.0,五氯酚的光解速率常数随之从25.30×10-4min-1增加到82.90×10-4min-1,而对硝基酚的光解速率常数相应从11.90×10-4min-1降低到了3.18×10-4min-1.苯酚的光解趋势与对硝基酚相似,当pH从4.0增加到11.0时,其光解速率常数依次从32.50×10-4min-1降低至13.40×10-4min-1.3种酚类化合物的光解总速率常数与解离度之间均满足幂函数变化规律.任意解离度条件下的解离态和非解离态光解速率常数,可根据幂函数的切线方程来确定.解离对酚类物质降解规律的影响主要是通过氧负离子的形成,改变苯环以及其他取代基团的活性而造成的.该研究结果为进一步了解天然水环境中酚类污染物的环境行为提供了理论参考. 相似文献
10.
Yuzhou Deng Shengpan Peng Haidi Liu Shuangde Li Yunfa Chen 《Frontiers of Environmental Science & Engineering》2019,13(2):21