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硝酸根对颗粒状铁降解三氯乙烯的影响(英文) 被引量:4
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作者 Qiong LU lai gui Robert W. GILLHAM 《地学前缘》 EI CAS CSCD 北大核心 2005年第U04期176-183,共8页
为研究硝酸根对颗粒状铁降解三氯乙烯的影响,进行了柱实验和相应的反应铁腐蚀电位测定。在硝酸根离子存在条件下,铁的腐蚀电位相应升高,系统条件也因之发生变化,导致钝性的铁氧化物在铁表面生成。因而,三氯乙烯和硝酸根离子降解速率明... 为研究硝酸根对颗粒状铁降解三氯乙烯的影响,进行了柱实验和相应的反应铁腐蚀电位测定。在硝酸根离子存在条件下,铁的腐蚀电位相应升高,系统条件也因之发生变化,导致钝性的铁氧化物在铁表面生成。因而,三氯乙烯和硝酸根离子降解速率明显减小, 并且降解速率减小的程度与硝酸根离子的浓度成比例。当污染液流过反应柱时,硝酸根离子与铁反应, 被还原为氨根离子。该反应造成硝酸根离子的浓度梯度,使钝化区在柱中上移,从而影响了三氯乙烯的降解曲线。与三氯乙烯单独与铁反应相比,当含4 7 mg/L硝酸根的三氯乙烯溶液流经反应柱170 孔隙体积后,降解50% 三氯乙烯所需的时间(t50) 从小于4 h增加到大于10 h;而当三氯乙烯溶液中加入100 mg/L硝酸根离子,仅17 孔隙体积溶液流经反应柱后,三氯乙烯降解t50就已大于14 h。研究结果表明,由于硝酸根离子对铁的腐蚀电位和铁表面氧化膜的不利作用,在处理靶污染物为高浓度硝酸根离子和三氯乙烯共同污染的地下水时,铁渗透反应隔栅不是最佳选择。如果靶污染物中硝酸根离子浓度比较低,则在设计铁隔栅时应考虑到硝酸根离子造成的不利因素,相应增加铁墙的厚度,从而确保三氯乙烯的降解效果。 展开更多
关键词 三氯乙烯 颗粒状 硝酸根离子 降解速率 孔隙体积 表面氧化膜 反应柱 电位测定 存在条件 发生变化 表面生成 铁氧化物 浓度梯度 研究结果 腐蚀电位 不利因素 降解效果 污染物 液流 钝化区 离子对 地下水 浓度比 减小 隔栅
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Three-dimensional measurements on the mandible of patients with hemifacial microsomia
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作者 Meng Wang lai gui 《Chinese Medical Journal》 SCIE CAS CSCD 2022年第8期971-976,共6页
Background:Hemifacial microsomia(HFM),which involves multiple sites with different levels of severity,is the second most common congenital craniofacial deformity after cleft lip and palate.However,three-dimensional(3D... Background:Hemifacial microsomia(HFM),which involves multiple sites with different levels of severity,is the second most common congenital craniofacial deformity after cleft lip and palate.However,three-dimensional(3D)measurements of mandibular deformities have not yet been studied in detail.The objective of this study is to investigate the method of 3D measurements of mandibular deformities in HFM patients.Methods:A total of 48 HFM patients were included in this study.All clinical treatment for patients was performed in the Plastic Surgery Hospital of the Chinese Academy of Medical Sciences at Peking Union Medical College from June 2006 to June 2020.The patients’3D computerized tomography scan data were processed using medical imaging software,following four iterative steps:3D reconstruction,mirroring,differential analysis,and partition.Results:The characteristics of the mandibular bone in HFM patients are mainly presented as follows:(1)compared to the normal side,the part of the bone body that extends from the ascending ramus to the pogonion(Po-NB)is analyzed using a dynamic process:less fullness-fullness-more fullness;(2)absences were frequently observed among the angular zones,that is,the height of the ascending ramus is deficient.Conclusions:HFM is a complicated condition with numerous variations in clinical presentation.We employed both 3D image reconstruction and computerization image processing techniques to investigate asymmetrical mandibular deformity in HFM patients in detail and with great accuracy.This will be of great use to clinicians for disease management. 展开更多
关键词 Hemifacial microsomia Mandibular deformity Three-dimensional measurement
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