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81.
We report on the prenatal diagnosis of ring chromosome 15 in a fetus with increased nuchal fold and intrauterine growth restriction (IUGR). A 27-year-old woman gravida 2, para 1 had normal maternal serum screen tests in the early second trimester of the index pregnancy. Fetal nuchal fold thickening up to 8 mm was incidentally found during the routine obstetric ultrasound scan at 20 weeks' gestation. Amniocentesis was undertaken and the fetal karyotype was found to be 46,XY,r(15) on cytogenetic study. Fluorescence in situ hybridization (FISH) using a telomeric probe of chromosome 15 demonstrated a terminal deletion on the q arm of the ring-shaped chromosome 15. This is the first report of a prenatally diagnosed case of ring chromosome 15. Moreover, nuchal fold thickness in the second trimester may have a role in its prenatal diagnosis. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
82.
Boundaries between different forest types in Changbai Mountain Eatern China are results from complex interactions between forest ecosystems,topogrphy,and geomorphology.Detecting and quantifying the transitional zones are highly important since high environmental beterogeneity and biodiversity are ofter found within these zpmes.In this study,we used GIS and multivariate statistics techniques(PCA and MSWA) to analyze data from Landsat TM satellite imageries and quantitatively determined the positions and widths of the landscape boundary betweeen mountain birch and evergreen coniferous forests in the northern slope of Changbai Mountain.The results showed that the widths of the landscape boundary ranges from 30-50 m while using the MWW A or/and PC method.Such detected widths are consistent with field transect data that suggest a 50m tranistional zone width.The results further suggest that TM data can be used in combination with GIS and statistical techniques in determining forest landscape boundaries.MSWA is more reliable than PCA,while PCA can also be used to determine the landscape boundary when transects are properly located. 相似文献
83.
Guobin Shan Rao Y. Surampalli Rajeshwar D. Tyagi Tian C. Zhang 《Frontiers of Environmental Science & Engineering in China》2009,3(3):249-264
Nanomaterials are applicable in the areas of reduction of environmental burden, reduction/treatment of industrial and agricultural
wastes, and nonpoint source (NPS) pollution control. First, environmental burden reduction involves green process and engineering,
emissions control, desulfurization/denitrification of nonrenewable energy sources, and improvement of agriculture and food
systems. Second, reduction/treatment of industrial and agricultural wastes involves converting wastes into products, groundwater
remediation, adsorption, delaying photocatalysis, and nanomembranes. Third, NPS pollution control involves controlling water
pollution. Nanomaterials alter physical properties on a nanoscale due to their high specific surface area to volume ratio.
They are used as catalysts, adsorbents, membranes, and additives to increase activity and capability due to their high specific
surface areas and nano-sized effects. Thus, nanomaterials are more effective at treating environmental wastes because they
reduce the amount of material needed. 相似文献
84.
Yingying Chen Ruiping Li Yan Gu Hailin Tian Yingping Huang Junsong Chen Yanfen Fang Changying Yang 《环境科学学报(英文版)》2021,33(2):203-215
Photocatalytic process represents a promising approach to overcome the pollution challenge associated with the antibiotics-containing wastewater. This study provides a green, efficient and novel approach to remove cephalosporins, particularly cefoperazone sodium (CFP). Bi4O5Br2 was chosen for the first time to systematically study its degradation for CFP, including the analysis of material structure, degradation performance, the structure and toxicity of the transformation products, etc. The degradation rate results indicated that Bi4O5Br2 had an excellent catalytic activity leading to 78% CFP removal compared with the pure BiOBr (38%) within 120 min of visible light irradiation. In addition, the Bi4O5Br2 presents high stability and good organic carbon removal efficiency. The effects of the solution pH (3.12 - 8.75) on catalytic activity revealed that CFP was mainly photocatalyzed under acidic conditions and hydrolyzed under alkaline conditions. Combined with active species and degradation product identification, the photocatalytic degradation pathways of CFP by Bi4O5Br2 was proposed, including hydrolysis, oxidation, reduction and decarboxylation. Most importantly, the identified products were all hydrolysis rather than oxidation byproducts transformed from the intermediate of β-lactam bond cleavage in CFP molecule, quite different from the mostly previous studies. Furthermore, the final products were demonstrated to be less toxic through the toxicity analysis. Overall, this study illustrates the detailed mechanism of CFP degradation by Bi4O5Br2 and confirms Bi4O5Br2 to be a promising material for the photodegradation of CFP. 相似文献
85.
86.
粗放型绿色屋顶对多环芳烃的控制效果 总被引:1,自引:1,他引:1
构建4个粗放型绿色屋顶中试设施,考察不同基质组成的设施在实际降雨条件下出水中16种多环芳烃(PAHs)质量浓度并与降雨、沥青屋面径流、空白对照设施的出水进行对比.结果表明,8场监测降雨事件中,4种模拟屋面设施出流PAHs的平均质量浓度分别为145、166、151、160 ng·L~(-1),沥青屋面和空白对照设施出流PAHs的平均质量浓度分别为900 ng·L-1和270 ng·L~(-1),4个模拟设施出流PAHs质量浓度显著低于沥青屋面和空白对照设施;从质量负荷控制的角度,4个模拟设施均能有效控制屋面径流PAHs负荷,与空白屋面相比,平均负荷削减率为71.76%.绿色屋顶对PAHs的去除机制以基质材料的截留及吸附为主,同样基质配比的情况下,增加基质层厚度,能改善设施对PAHs的去除效果.将传统沥青屋面改造为粗放型绿色屋顶,有助于控制屋面径流PAHs排放. 相似文献
87.
88.
We explored the feasibility and removal mechanism of removing 2-chlorobiphenyl(2-Cl BP)from soil–water system using granular activated carbon(GAC) impregnated with nanoscale zerovalent iron(reactive activated carbon or RAC).The RAC samples were successfully synthesized by the liquid precipitation method.The mesoporous GAC based RAC with low iron content(1.32%) exhibited higher 2-Cl BP removal efficiency(54.6%) in the water phase.The result of Langmuir–Hinshelwood kinetic model implied that the different molecular structures between 2-Cl BP and trichloroethylene(TCE) resulted in more difference in dechlorination reaction rates on RAC than adsorption capacities.Compared to removing2-Cl BP in the water phase,RAC removed the 2-Cl BP more slowly in the soil phase due to the significant external mass transfer resistance.However,in the soil phase,a better removal capacity of RAC was observed than its base GAC because the chemical dechlorination played a more important role in total removal process for 2-Cl BP.This important result verified the effectiveness of RAC for removing 2-Cl BP in the soil phase.Although reducing the total RAC removal rate of 2-Cl BP,soil organic matter(SOM),especially the soft carbon,also served as an electron transfer medium to promote the dechlorination of 2-Cl BP in the long term. 相似文献
89.
90.
钙钛矿型烯土复合氧化物及其在汽车尾气净化工程中的应用 总被引:3,自引:0,他引:3
本文介绍了钙铁矿型烯土复合氧化物的结构特征、制备方法与催化性能;分析了该类氧化物对汽车尾气环境的适应性,并与现有的贵金属催化剂作了比较. 相似文献