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Mg/O共同修饰无定形氮化碳的独特电子结构增强光催化对四环素盐酸盐的降解(英文) 被引量:6
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作者 吴晓璐 傅敏 +2 位作者 卢鹏 任秋燕 汪成 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第5期776-785,共10页
近年来,光催化技术被广泛应用于环境和能源领域.其中,g-C_3N_4因化学稳定性和热稳定性好、能带结构易调控而成为一种有前景的可见光光催化剂.然而,g-C_3N_4的电子-空穴对易复合,导致其不能充分利用太阳光,光催化效率并不理想.本文通过... 近年来,光催化技术被广泛应用于环境和能源领域.其中,g-C_3N_4因化学稳定性和热稳定性好、能带结构易调控而成为一种有前景的可见光光催化剂.然而,g-C_3N_4的电子-空穴对易复合,导致其不能充分利用太阳光,光催化效率并不理想.本文通过实验与理论结合的方法设计并制备了具有独特电子结构的Mg/O共同修饰的无定形氮化碳(记为MgO-CN),以30mg/L的四环素盐酸溶液(TC)作为目标污染物评价了其光催化性能.经X射线衍射、扫描电镜、透射电镜、N_2物理吸附、紫外-可见光谱等表征手段分析表明,MgO-CN样品(002)晶面的衍射峰强度随着MgO含量增加而减弱,CN趋向于无定形化.同时,MgO-CN样品的可见光吸收边带发生红移,呈现出更强的可见光吸收能力.此外,Mg原子和O原子共同修饰的独特电子结构可以通过C→O←Mg的电子传递路线在O原子周围产生局域电子,从而抑制电子-空穴的复合.光催化降解TC的实验结果表明,在可见光照射后,含有1.2 wt%MgO的复合样品MgO-CN-1.2具有最佳光催化活性,TC降解效率为82.0%,比g-C_3N_4的光催化效率(23.5%)高出58.5%,且光催化降解过程符合准一级动力学,MgO-CN-1.2的反应速率常数(0.01018 min^(–1))是g-C_3N_4(0.00205 min^(–1))的5倍.自由基捕获测试实验表明,g-C_3N_4和Mg O-CN-1.2样品均可以产生·O_2~–自由基和·OH自由基,但是Mg O-CN-1.2样品的·O_2~–和·OH信号更强.这是由于Mg O-CN-1.2样品可以吸收更大范围的可见光用于激发电子,同时结合理论计算证明,MgO-CN内部电子在O原子周围汇集,形成的电子定向传输通道对催化剂表面的电子-空穴复合有抑制作用,更加有利于电子的迁移而诱导O_2生成·O_2~–.由于Mg O-CN-1.2和g-C_3N_4的价带位置分别位于1.47和1.60 eV,此价带上的h^+不能与H_2O和OH~–直接反应生成·OH,而是由生成的·O_2~–再与H^+和e~–按照O_2→·O_2→H_2O_2→·OH的反应途径生成·OH.本文最后分析,MgO-CN复合物参与反应的主要活性物种为·O_2~–,·OH和h^+光催化降解污染物的反应机理.其中,·O_2~–对光催化降解TC的贡献最大,为最主要的活性物质.本文工作提供了一种新的策略来改变氮化碳的电子结构,对提高其催化性能具有积极意义. 展开更多
关键词 氮化硅 电子结构 可见光光催化 四环素盐酸盐降解 环境修复
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Clinicopathological and prognostic role of MMP-9 in esophageal squamous cell carcinoma: a meta-analysis 被引量:5
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作者 Rong Zeng Lei Duan +4 位作者 Yuke Kong Yaojun Liang xiaolu wu Xuequan Wei Kehu Yang 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 2013年第6期637-645,共9页
Objective: Many studies reported that matrix metalloproteinase-9 (MMP-9) participated in the development of esophageal squamous cell carcinoma (ESCC) and resulted in poor prognosis, however, they all included few... Objective: Many studies reported that matrix metalloproteinase-9 (MMP-9) participated in the development of esophageal squamous cell carcinoma (ESCC) and resulted in poor prognosis, however, they all included few patients and had inconsistent results. So we conducted a meta-analysis to explore the correlation between overexpression of MMP-9 and the clinicopathological characteristics and overall survival (OS) of ESCC. Methods: PubMed, EMBASE, Web of Science, Chinese Biomedical Literature Database, Google Scholar and other databases were searched for relevant studies. The Newcastle-Ottawa quality assessment scale was used to assess the methodological quality of included study and RevMan 5.2 software was used to conduct meta-analysis. Results: A total of 35 studies were included, and the results of meta-analysis showed that overexpression of MMP-9 was associated with grade of differentiation [well/moderate vs. poor: odds ratio (OR): 0.39, 95% confidence interval (CI): 0.29-0.52; P〈0.00001], lymph node metastasis (negative vs. positive: OR: 0.24, 95% CI: 0.16-0.34; P〈0.00001), TNM stage (T1/T2 vs. T3/T4: OR: 0.28, 95% CI: 0.14-0.54; P=0.0002), the depth of invasion (T1/T2 vs. T3/T4: OR: 0.29, 95% CI: 0.17-0.49; P〈0.00001), and vascular invasion of ESCC (negative vs. positive: OR: 0.35, 95% CI: 0.21-0.58; P〈0.0001), and also associated with poor overall survival ofESCC (HR: 2.17, 95% CI: 1.32-3.57; P=0.002). Subgroup analysis showed that more than 10% of carcinoma cell staining was associated with significant increase of mortality risk (HR: 2.44, 95 % CI: 1.16-5.15; P=0.02), and sensitive analysis suggested that MMP-9 was an independent prognostic factor in ESCC (HR: 1.49, 95% CI: 1.16-1.91; P=0.002). Conclusions:On the basis of limited evidence, overexpression of MMP-9 may be a potential independent prognosis factor of ESCC patients in Asia, and high-quality studies assessing the prognostic significance of MMP-9 for ESCC patients are still needed. 展开更多
关键词 Matrix metalloproteinase-9 (MMP-9) esophageal squamous cell carcinoma (ESCC) overall survival(OS) META-ANALYSIS
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Mechanism and Countermeasures for Action of Scientific and Technological Innovation on Integration of Industrialization and Urbanization 被引量:1
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作者 xiaolu wu 《Asian Agricultural Research》 2020年第11期9-15,共7页
In the current process of deepening reform in China,industrial structure upgrading,economic structural transformation and new urbanization are important tasks to promote social and economic development,and technologic... In the current process of deepening reform in China,industrial structure upgrading,economic structural transformation and new urbanization are important tasks to promote social and economic development,and technological innovation has gradually become the primary driving force for industrial upgrading,economic transformation and the realization of new urbanization.The article analyzed the action mechanism of scientific and technological innovation on the integration of industrialization and urbanization through qualitative and quantitative methods,found out the prominent problems faced by Henan through the empirical analysis of relevant data of Henan Province,and then proposed the integrated development path driven by scientific and technological innovation. 展开更多
关键词 Technological innovation Integration of industrialization and urbanization Coupling coordination degree New urbanization
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