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6.
In a case of hydrops fetalis, serological examination showed a recent maternal human parvovirus B19 infection. Amniocentesis revealed a unique unbalanced translocation between chromosomes 3 and 11 of the fetus. The mother proved to have a balanced reciprocal translocation between chromosomes 3 and 11. A grossly macerated hydropic male fetus was delivered with a flat nose and low implanted deformed ears. Histopathological examination revealed nuclear inclusion bodies in fetal erythroid cells, confirming human parvovirus B19 infection. Parvovirus B19 DNA was demonstrated by in situ hybridization in the nuclei of heart muscle cells. Our finding of two different disorders in one case illustrates the importance of a complete evaluation of every case of hydrops fetalis, especially concerning counselling on the outcome of future pregnancies. The human parvovirus B19 infection will not recur due to the acquired immunity of the mother, whereas the balanced reciprocal translocation will endanger future pregnancies. 相似文献
9.
The degradation of water source environment becomes serious problems accompanying with rapid urbanization in China.Ecological engineering provides ecologically sound and cost-effective solution to solving this problem. As a case study, a 15 hm^2 ecological water storage basin for a water plant was designed and constructed on the TEDA area in Tianjin City. Located on saline, the construction of this project has to face serious difficulties, such as high salinity, scarce seed banks of macrophytes, and strong winds. Freshwater replacement, soil amendation and macrophytes planting at the basinshore, wooden water breaker and plastic membrane installation and other measures were conducted for the assistance of plant community establishment. The result showed that the chloride concentration in the basin water decreased from 11600 mg/L to less than 100 mg/L, and the chloride content in the basin sediment decreased from 2.1% to 0. 35 % after freshwater soaking. The introduced macrophytes of 8 species all survived and 11 other macrophytes species were occurred in the basin. A new ecosystem was created with increased biological diversity in the original saline, and the water quality was improved. This ecological water storage basin also provided a pleasing landscape for local people. 相似文献
10.
In a 20-year-old primiparous patient, a routine ultrasound scan performed at 28 weeks revealed fetal ascites, bilateral talipes, and oligohydramnios. This woman, married to possibly her first cousin, was at risk for an autosomal recessive disease, a metabolic disorder. At 29 weeks, an amniotic fluid biochemical study revealed the presence of an abnormal band of free sialic acid, leading to a diagnosis of a congenital form of sialic acid storage disease. Termination of pregnancy was performed at 30 weeks. Measurement of free sialic acid in cultured fetal skin fibroblasts confirmed the diagnosis. 相似文献
11.
Lake eutrophication has increasingly become a major environmental issue in China.Although significant efforts have been made towards its resolution in the last decade,most of the implemented control strategies are fragmented,and the formation of policy lacks of sound scientific basis and long-term objectives.Taking the well-known Dianchi Lake as a case study,this paper presented a comprehensive assessment for the effectiveness of various eutrophication control strategies.It is expected that the concluding lessons would have a major implication to future eutrophication control. 相似文献
12.
Data from 23 twin pregnancies with one structurally affected fetus were compared with data from 23 twin pregnancies with proven absence of structural fetal anomalies and matched for maternal age, parity, and year of delivery. The preterm delivery rate ( < 37 weeks) was high in both groups but not significantly different (57 vs. 48 per cent). Perinatal mortality was significantly higher in the structurally affected twin pregnancies (65 vs. 9 per cent). In the affected twins, birth weight of the anomalous fetus was significantly lower than that of the normal co-twin. Since there was no difference in the incidence of maternal disease (hypertensive disorders, diabetes), it was concluded that the higher perinatal mortality was determined mainly by the nature of the anomaly and not by the preterm delivery rate. 相似文献
14.
考虑资源承载力 (R)和生活舒适度 (S)对适度人口的影响 ,以不同经济发展水平下的人口现状为依据 ,提出R S双向寻优方法进行城市适度人口分析 .并以广州市为例 ,寻求其最优人口容量 .结果表明 ,现有资源承载力与经济水平下的广州人口规模略高于适度人口规模 ,需要进行人口与经济密度的重新布局 . 相似文献
15.
排污许可证制度是目前普遍采用的水环境管理的重要制度之一,在水污染控制和水环境质量改善中发挥着重要作用。通过将基于水环境容量约束和基于流域排放标准的允许排放量进行对比,构建了控制单元排污许可总量限值管理模式和污染源排污许可总量限值优化方法。基于永定河流域典型控制单元的实证研究表明,在执行流域排放标准时,北京段典型控制单元可满足水环境质量改善需求,但张家口段典型控制单元仍需要削减CODCr 210.388 t/a。张家口段典型控制单元内2家污水处理厂上游间接排放固定源需分别削减CODCr 0.002和32.039 t/a。 相似文献
16.
Hydrogen is an important utility in the production of clean fuels such as low-sulfur gasoline and diesel. The shortage of hydrogen resource motivates the integrated management of hydrogen networks with purifiers. In this paper, we propose a systematic approach for the retrofit design of these hydrogen networks. By establishing a state-space superstructure, all possible placements of existing compressors and purifiers are incorporated in the proposed MINLP model. Total annual cost (TAC) is employed as the optimizing object to understand the trade-offs between operating cost and capital cost. A real refinery system near Shanghai of China city is used to illustrate the applicability of the approach. 相似文献
17.
The highly permeable sand and gravel of the Little Miami River Valley Aquifer System near Milford, Ohio provide the community with a high-yielding source of drinking water. While this hydrogeologic setting is ideal from a water quantity standpoint, it is greatly vulnerable to contamination. The future viability of the well-field came into question when it was discovered that the wellfield was contaminated with volatile organic contaminants, leaving the City with the costly cleanup. Milford’s perseverance is also challenged by having to deal with a deteriorating treatment plant. Furthermore, larger water suppliers in the area have threatened the community’s independence. The question facing this community, and many other smaller communities, was whether to surrender its independence or invest in their future. The city has decided to keep their wellfield and to conduct a groundwater study. The objectives of the study were to: (a) collect and evaluate hydrogeological data; (b) develop a conceptual model of the groundwater system; (c) construct groundwater flow and geochemical models; (d) delineate wellhead protection area; and (e) develop a comprehensive management program. Collected hydro-geologic data served as a basis for the conceptual model. The U.S. Geological Survey (USGS) three-dimensional groundwater flow model MODFLOW was used in conjunction with MODPATH, a particle-tracking program, to identify travel times and paths of contaminants. This approach ultimately lead to the delineation of the wellhead protection area (WHPA). Geochemical mixing models were constructed using the USGS PHREEQC to verify the flow model results. The use of both flow and geochemical models to delineate the WHPA and to manage groundwater resources is a unique approach. The modeling results provide the City of Milford a management tool in making difficult policy decisions regarding future land use, siting for new monitoring and production wells, and identification of potential pollution sources. 相似文献
18.
One of the most critical issues in the production of low-sulphur fuels is managing the impact of the new environmental requirements on the hydrogen balance of the refinery. The combination of low-sulphur fuel specifications and reduced production of hydrogen in catalytic reformers make hydrogen management a critical issue. More efficient use of hydrogen thus becomes unavoidable. This paper addresses the problem of the actual hydrogen distribution at the Porto Refinery of the GALP ENERGIA network, and uses a new tool based on the concept of hydrogen surplus. By means of different methodologies and resorting to linear programming, an efficient network design has been achieved that reduces the hydrogen utilities usage by 30% (achieving 30% more gas to the fuel system), while also dealing with the complexity and need for flexibility so characteristic of a refinery as well as the reduction of operating costs related to the pneumatic system. In terms of hydrogen manufacturing reduction in the platformings, it is possible to reduce by 6%. 相似文献
19.
The black soil region in Northeast China is an important region for cereal grain production in the country. However, several decades of overexploitation and unsustainable land use practices have caused substantial loss of soil and soil productivity. The dominant soil erosion processes in the black soil region are water, wind and meltwater erosion, of which water erosion on the slope farmland is the major contributor to soil erosion. According to landforms and characteristics of soil and water loss, the black soil region of Northeast China can be classified as the rolling hill area, the low mountain–hill ravine area, and the farming-pastoral area. As a result, land use strategies, including the Three Defense Lines control pattern, the Pyramid Style control pattern, and the control pattern of Minimum Exploiture and Maximal Protection, are proposed for the three respective areas. Moreover, conservation tillage and participatory management are the promising measures that have not been widely implemented in the black soil region until now. 相似文献
20.
以宁夏境内黄河最大的一级支流清水河流域为例,分析重点断面水质、水环境容量及各控制单元污染负荷特征,并提出有针对性的污染控制策略。结果表明:2015—2018年清水河三营国控断面水质无法稳定达到GB 3838—2002《地表水环境质量标准》Ⅳ类水质标准,泉眼山断面化学需氧量(COD)存在超Ⅳ类水质标准风险。流域水环境容量COD为592.83~1 238.25 t/a,氨氮为51.99~193.60 t/a,总磷(TP)为5.02~12.85 t/a;流域平水期污染负荷入河量COD为15 661.1 t/a,氨氮为1 670.2 t/a,TP为784.5 t/a,分别是平水期水环境容量(COD为940.57 t/a,氨氮为114.64 t/a,TP为8.81 t/a)的16、14和89倍。固原控制单元单位面积污染负荷入河量最高(COD为3.04 t/a,氨氮为0.22 t/a,TP为0.06 t/a),工业源与城镇生活源污染问题突出,中卫控制单元总污染负荷入河量最高(COD为 6 738.45 t/a,氨氮为868.88 t/a,TP为218.12 t/a),城镇生活源污染较严重,而吴忠控制单元禽畜养殖污染较严重。基于水质目标和各单元的污染特征,建议固原控制单元加强工业企业污水回收利用、提高城镇污水处理能力,中卫控制单元重点关注污水收集处理设施建设与改造升级,吴忠控制单元在规模化养殖场推行禽畜粪污集中处理与回用。 相似文献
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