光催化二氧化碳还原成烃类化合物是解决能源短缺和环境污染的重要途径。而构建复合物光催化剂可以有效地解决单一光催化剂的缺点,并且提高二氧化碳还原活性。尽管对复合物光催化剂已经做了很多研究,然而对其活性增强的内在机制还缺乏理...光催化二氧化碳还原成烃类化合物是解决能源短缺和环境污染的重要途径。而构建复合物光催化剂可以有效地解决单一光催化剂的缺点,并且提高二氧化碳还原活性。尽管对复合物光催化剂已经做了很多研究,然而对其活性增强的内在机制还缺乏理论认识。本文采用密度泛函理论计算方法研究了二维/二维BP/g-C_(3)N_(4)复合模型的电子性质和CO_(2)还原反应过程。通过对能带位置和界面电子相互作用的综合分析发现,在BP/g-C_(3)N_(4)异质结中,光生载流子的迁移遵循S型异质结光催化机制。与单一的g-C_(3)N_(4)相比,这种异质结可以实现光生载流子的高效分离并且拥有良好的氧化还原能力。此外,通过对比研究CO_(2)在g-C_(3)N_(4)和BP/g-C_(3)N_(4)还原反应过程发现,异质结使CO_(2)还原反应的最大能垒从1.48 e V降低到1.22e V。因此,BP/g-C_(3)N_(4)异质结在理论上被证明是一种优良的CO_(2)还原光催化剂。这项工作有助于了解BP改性对g-C_(3)N_(4)光催化活性的影响,也为其他高性能CO_(2)还原光催化剂的设计提供理论依据。展开更多
过氧化氢作为一种对环境友好的、重要的化学原料,被广泛用于化学工业、漂白剂和废水处理等领域.近几十年来,过氧化氢主要通过蒽醌工艺生产.然而,该方法需要多步蒽醌加氢和氧化反应,导致较高的生产成本和能量消耗,同时伴随着大量的二氧...过氧化氢作为一种对环境友好的、重要的化学原料,被广泛用于化学工业、漂白剂和废水处理等领域.近几十年来,过氧化氢主要通过蒽醌工艺生产.然而,该方法需要多步蒽醌加氢和氧化反应,导致较高的生产成本和能量消耗,同时伴随着大量的二氧化碳排放.另一种替代策略是在贵金属催化剂的辅助下,由氢气和氧气的混合气体在高温下直接合成.但是,氢气和氧气的混合气体在高温下存在爆炸的危险,从而限制了其大规模应用.因此,探索一种低能耗、温和条件下生产过氧化氢具有重要的意义.太阳能驱动光催化生产过氧化氢是解决上述问题的理想途径.通常认为,过氧化氢是由直接双电子还原(E(O2/H2O2)=0.68 V vs.NHE)或间接单电子O2还原(E(O2/•O2−)=-0.33 V vs.NHE)产生的.氧化锌半导体具有很的稳定性好、环保和成本低等优点,因此经常被用于二氧化碳的光催化还原、污水处理和气体传感器等领域.氧化锌的导带电势(ECB=-0.5 V vs.NHE)比氧还原电势更负,意味着它在热力学上满足光催化过氧化氢生产的要求.然而,目前关于氧化锌的光催化生产过氧化氢的研究尚未受到较多的关注.本文采用简单的水热法制备了一维氧化锌纳米棒,在不同温度下热处理后,对其形貌和结构、光学性质和电化学性质进行了表征.同时,系统地研究了以乙醇为牺牲剂光催化生产过氧化氢的性能.结果表明,随着焙烧温度的升高,氧化锌纳米棒内部的氧空位被空气中的氧气重新填充,其催化生成过氧化氢的活性先升高后降低.经300ºC焙烧的氧化锌光催化产过氧化氢的活性最好,为285μmol L-1 h-1.同时,对过氧化氢的生成机理研究结果表明,该过程中为间接单电子O2还原过程.氧气先与一个电子反应生成超氧自由基,再与两个质子和一个电子反应生成过氧化氢分子.综上,本文为氧化锌纳米棒光催化产过氧化氢的机理研究提供了新认识,并提出了一种有前途的过氧化氢生产策略.展开更多
Coronary artery disease (CAD) is a multifactorial disease in which inflammation plays a central role. This study aimed to investigate the association of inflammatory markers such as the neutrophil to lymphocyte rat...Coronary artery disease (CAD) is a multifactorial disease in which inflammation plays a central role. This study aimed to investigate the association of inflammatory markers such as the neutrophil to lymphocyte ratio (NLR), the Global Registry of Acute Coronary Events (GRACE) score with in-hospital mortality of elderly patients with acute myocardial infarction (AMI) in an attempt to explore the prognostic value of these indices for elderly AMI patients. One thousand consecutive CAD patients were divided into two groups based on age 60. The laboratory and clinical characteristics were assessed retrospectively by reviewing the medical records. The NLR and GRACE score were calculated. In the elderly (〉60 years), patients with non-ST-elevation myocardial infarction (NSTEMI) and ST-elevation myocardial infarction (STEMI) had significantly higher NLR than did those with unstable angina (UA) and stable angina pectoris (SAP) (P〈0.01). The NLR was considerably elevated in older AMI patients compared with their younger counterparts (〈60 years) (P〈0.05). In elderly AMI patients, the NLR was considerably higher in the high-risk group than in both the low-risk and mediumrisk groups based on the GRACE score (P〈0.05 and P〈0.01, respectively), and the NLR was positively correlated with the GRACE score (r=0.322, P〈0.001). Either the NLR level or the GRACE score was significantly higher in the death group than in the surviving group (P〈0.05). By curve receiver operator characteristic curve (ROC) analysis, the optimal cut-off levels of 9.41 for NLR and 174 for GRACE score predicted in-hospital death [ROC area under the curve (AUC) 0.771 and 0.787, respectively, P〈0.001]. It was concluded that an elevated NLR is a potential predictor of in-hospital mortality in elderly patients with AMI.展开更多
基金supported by the National Natural Science Foundation of China(U1705251,21871217,21573170,21433007)the National Key Research and Development Program of China(2018YFB1502001)~~
基金supported by the National Natural Science Foundation of China(51602207,21433007,51320105001,21573170)the Self-determined and Innovative Research Funds of SKLWUT(2017-ZD-4,2016-KF-17)the Natural Science Foundation of Hubei Province of China(2015CFA001)~~
文摘光催化二氧化碳还原成烃类化合物是解决能源短缺和环境污染的重要途径。而构建复合物光催化剂可以有效地解决单一光催化剂的缺点,并且提高二氧化碳还原活性。尽管对复合物光催化剂已经做了很多研究,然而对其活性增强的内在机制还缺乏理论认识。本文采用密度泛函理论计算方法研究了二维/二维BP/g-C_(3)N_(4)复合模型的电子性质和CO_(2)还原反应过程。通过对能带位置和界面电子相互作用的综合分析发现,在BP/g-C_(3)N_(4)异质结中,光生载流子的迁移遵循S型异质结光催化机制。与单一的g-C_(3)N_(4)相比,这种异质结可以实现光生载流子的高效分离并且拥有良好的氧化还原能力。此外,通过对比研究CO_(2)在g-C_(3)N_(4)和BP/g-C_(3)N_(4)还原反应过程发现,异质结使CO_(2)还原反应的最大能垒从1.48 e V降低到1.22e V。因此,BP/g-C_(3)N_(4)异质结在理论上被证明是一种优良的CO_(2)还原光催化剂。这项工作有助于了解BP改性对g-C_(3)N_(4)光催化活性的影响,也为其他高性能CO_(2)还原光催化剂的设计提供理论依据。
文摘过氧化氢作为一种对环境友好的、重要的化学原料,被广泛用于化学工业、漂白剂和废水处理等领域.近几十年来,过氧化氢主要通过蒽醌工艺生产.然而,该方法需要多步蒽醌加氢和氧化反应,导致较高的生产成本和能量消耗,同时伴随着大量的二氧化碳排放.另一种替代策略是在贵金属催化剂的辅助下,由氢气和氧气的混合气体在高温下直接合成.但是,氢气和氧气的混合气体在高温下存在爆炸的危险,从而限制了其大规模应用.因此,探索一种低能耗、温和条件下生产过氧化氢具有重要的意义.太阳能驱动光催化生产过氧化氢是解决上述问题的理想途径.通常认为,过氧化氢是由直接双电子还原(E(O2/H2O2)=0.68 V vs.NHE)或间接单电子O2还原(E(O2/•O2−)=-0.33 V vs.NHE)产生的.氧化锌半导体具有很的稳定性好、环保和成本低等优点,因此经常被用于二氧化碳的光催化还原、污水处理和气体传感器等领域.氧化锌的导带电势(ECB=-0.5 V vs.NHE)比氧还原电势更负,意味着它在热力学上满足光催化过氧化氢生产的要求.然而,目前关于氧化锌的光催化生产过氧化氢的研究尚未受到较多的关注.本文采用简单的水热法制备了一维氧化锌纳米棒,在不同温度下热处理后,对其形貌和结构、光学性质和电化学性质进行了表征.同时,系统地研究了以乙醇为牺牲剂光催化生产过氧化氢的性能.结果表明,随着焙烧温度的升高,氧化锌纳米棒内部的氧空位被空气中的氧气重新填充,其催化生成过氧化氢的活性先升高后降低.经300ºC焙烧的氧化锌光催化产过氧化氢的活性最好,为285μmol L-1 h-1.同时,对过氧化氢的生成机理研究结果表明,该过程中为间接单电子O2还原过程.氧气先与一个电子反应生成超氧自由基,再与两个质子和一个电子反应生成过氧化氢分子.综上,本文为氧化锌纳米棒光催化产过氧化氢的机理研究提供了新认识,并提出了一种有前途的过氧化氢生产策略.
基金This project was supported by a grant from Hubei Natural Science Foundation of China (No. 2013CKB011).
文摘Coronary artery disease (CAD) is a multifactorial disease in which inflammation plays a central role. This study aimed to investigate the association of inflammatory markers such as the neutrophil to lymphocyte ratio (NLR), the Global Registry of Acute Coronary Events (GRACE) score with in-hospital mortality of elderly patients with acute myocardial infarction (AMI) in an attempt to explore the prognostic value of these indices for elderly AMI patients. One thousand consecutive CAD patients were divided into two groups based on age 60. The laboratory and clinical characteristics were assessed retrospectively by reviewing the medical records. The NLR and GRACE score were calculated. In the elderly (〉60 years), patients with non-ST-elevation myocardial infarction (NSTEMI) and ST-elevation myocardial infarction (STEMI) had significantly higher NLR than did those with unstable angina (UA) and stable angina pectoris (SAP) (P〈0.01). The NLR was considerably elevated in older AMI patients compared with their younger counterparts (〈60 years) (P〈0.05). In elderly AMI patients, the NLR was considerably higher in the high-risk group than in both the low-risk and mediumrisk groups based on the GRACE score (P〈0.05 and P〈0.01, respectively), and the NLR was positively correlated with the GRACE score (r=0.322, P〈0.001). Either the NLR level or the GRACE score was significantly higher in the death group than in the surviving group (P〈0.05). By curve receiver operator characteristic curve (ROC) analysis, the optimal cut-off levels of 9.41 for NLR and 174 for GRACE score predicted in-hospital death [ROC area under the curve (AUC) 0.771 and 0.787, respectively, P〈0.001]. It was concluded that an elevated NLR is a potential predictor of in-hospital mortality in elderly patients with AMI.