The microstructure and mechanical properties of Mg-xCe-0.5Zn （x=0.5, 1.5, 2.5, molar fraction, %） alloys were examined using a nano-indentation technique. The alloys were fabricated using a vacuum induction melting ...The microstructure and mechanical properties of Mg-xCe-0.5Zn （x=0.5, 1.5, 2.5, molar fraction, %） alloys were examined using a nano-indentation technique. The alloys were fabricated using a vacuum induction melting method under an argon atmosphere The microstruetures of Mg-xCe-0.5Zn alloys mainly consist ofa-Mg and eutectic Mg12Ce phase. The volume fraction and size of the eutectic Mgl2Ce phase increase with increasing Ce contents. Nano-indentation test results show that the indentation hardness and elastic modulus of the eutectic Mg12Ce phase are higher than those of the a-Mg matrix. In addition, the mean indentation hardness and elastic modulus of the Mg-xCe-0.5Zn alloys increase with the Ce addition amount increasing.展开更多
采用基于密度泛函理论的M06-2X和MN15方法,结合处理溶剂效应的SMD模型方法,研究了水液相下两性赖氨酸二价镁配合物(Lys→Mg(Ⅱ))的对映异构.发现Lys→Mg(Ⅱ)的对映异构可通过质子转移和R基的CC键旋转过程实现.考察了3个反应通道a、b和c...采用基于密度泛函理论的M06-2X和MN15方法,结合处理溶剂效应的SMD模型方法,研究了水液相下两性赖氨酸二价镁配合物(Lys→Mg(Ⅱ))的对映异构.发现Lys→Mg(Ⅱ)的对映异构可通过质子转移和R基的CC键旋转过程实现.考察了3个反应通道a、b和c,它们分别是S-Lys→Mg(Ⅱ)先失去手性,然后R-基C-C键旋转,最后实现对映体异构;S-Lys→Mg(Ⅱ)先手性转变,然后R-基C-C键旋转实现对映体异构;S-Lys→Mg(Ⅱ)先从两性向中性异构,然后实现手性转变,最后通过R-基C-C键旋转实现对映体异构.计算表明,c通道最优势,隐性溶剂效应下决速步的自由能垒是204.4 k J/mol,显性溶剂效应下该能垒降到103.9-109.9 k J/mol之间.结果表明,水液相下Lys→Mg(Ⅱ)的对映异构过程很慢,赖氨酸二价镁可短期用于生命体同补赖氨酸和二价镁.展开更多
Biodegradable magnesium（Mg）-based vascular stents have been designed as temporary scaffolds to treat angiostenotic lesions for the maintenance of normal blood flow.Numerous studies have presented in vitro and in viv...Biodegradable magnesium（Mg）-based vascular stents have been designed as temporary scaffolds to treat angiostenotic lesions for the maintenance of normal blood flow.Numerous studies have presented in vitro and in vivo tests for the evaluation of the safety and feasibility of Mg-based vascular stents and the related materials. Therein the cytocompatibility is a basic and important parameter in the evaluation system. In this review, we summarize the applications and limitations of in vitro evaluation methods including basic characterization methods and direct and indirect cytotoxicity tests. We discuss the influencing factors on cytotoxicity, such as surface roughness, preconditioning of sample surface, cell type for the biocompatibility evaluation in direct contact as well as conditions for the formation of extracts/degradation products for indirect assays. Besides, we highlight the recent in vivo animal tests and clinical trials about Mgbased stents along with some associated results. The aim of this review is to provide a meaningful reference in the further developments and related evaluation methods of Mg-based stents.展开更多
In order to provide evidence for making clinical decision, the role of intravenous and nebulized MgSO4 in treatment of adult＇s acute asthma was systematically estimated in the present study. Pubmed, Embase, Web of Sc...In order to provide evidence for making clinical decision, the role of intravenous and nebulized MgSO4 in treatment of adult＇s acute asthma was systematically estimated in the present study. Pubmed, Embase, Web of Sciences, the Cochrane Library and two Chinese literature databases （CNKI, WanFang） were systematically searched up to January 2016. Randomized controlled trails （RCTs） that compared the clinical outcomes of MgSO4 groups and placebo groups were included. The primary outcome was hospital admission. Secondary outcomes included pulmonary function, symptom scores, vital signs and adverse events. The methodological quality of the included studies was evaluated, and the forest plots with meta-analysis were drawn by RevMan 5.2. A total of 24 RCTs derived from 2931 patients were included. Both intravenous MgSO4 and nebulized MgSO4 treatments had no effect upon hospital admission （RR 0.91, 95% CI 0.80 to 1.03, P = 0.14; RR 0.78, 95% CI 0.56 to 1.08, P = 0.14）. Both intravenous MgSO4 and nebulized MgSO4 treatments were associated with significant evidence upon respiratory function （SMD 0.23, 95% CI 0.03 to 0.43, P = 0.02; SMD 0.37, 95% CI 0.11 to 0.64, P = 0.006）, but sensitivity analyses showed that outcomes were changed by omitting studies of less than 100 individuals （SMD 0.05, 95% C1-0.05 to 0.15, P = 0.35; SMD 0.05, 95% C1-0.16 to 0.25, P = 0.64）. There were no statistically significant differences in clinical symptom scores and vital signs （heart or pulse rate; systolic blood pressure; respiratory rate） in either form of MgSO4 compared with placebo groups （P〉0.05）. There were no serious adverse events reported in any literature. Overall, there was no role for intravenous and nebulized MgSO4 in the management of acute asthma in adults. Considering the low risk of serious adverse effects and easy availability, it seemed reasonable to use intravenous or nebulized MgSO4 treatment in adults with life threatening asthma in whom any potential benefit would justify the risks of treatment.展开更多
基金supported by a grant-in-aid for the National Core Research Center Program(No.R15-2006-022-02001-0)the Metals Bank project of the Korea Ministry of Knowledge Economy
文摘The microstructure and mechanical properties of Mg-xCe-0.5Zn （x=0.5, 1.5, 2.5, molar fraction, %） alloys were examined using a nano-indentation technique. The alloys were fabricated using a vacuum induction melting method under an argon atmosphere The microstruetures of Mg-xCe-0.5Zn alloys mainly consist ofa-Mg and eutectic Mg12Ce phase. The volume fraction and size of the eutectic Mgl2Ce phase increase with increasing Ce contents. Nano-indentation test results show that the indentation hardness and elastic modulus of the eutectic Mg12Ce phase are higher than those of the a-Mg matrix. In addition, the mean indentation hardness and elastic modulus of the Mg-xCe-0.5Zn alloys increase with the Ce addition amount increasing.
文摘采用基于密度泛函理论的M06-2X和MN15方法,结合处理溶剂效应的SMD模型方法,研究了水液相下两性赖氨酸二价镁配合物(Lys→Mg(Ⅱ))的对映异构.发现Lys→Mg(Ⅱ)的对映异构可通过质子转移和R基的CC键旋转过程实现.考察了3个反应通道a、b和c,它们分别是S-Lys→Mg(Ⅱ)先失去手性,然后R-基C-C键旋转,最后实现对映体异构;S-Lys→Mg(Ⅱ)先手性转变,然后R-基C-C键旋转实现对映体异构;S-Lys→Mg(Ⅱ)先从两性向中性异构,然后实现手性转变,最后通过R-基C-C键旋转实现对映体异构.计算表明,c通道最优势,隐性溶剂效应下决速步的自由能垒是204.4 k J/mol,显性溶剂效应下该能垒降到103.9-109.9 k J/mol之间.结果表明,水液相下Lys→Mg(Ⅱ)的对映异构过程很慢,赖氨酸二价镁可短期用于生命体同补赖氨酸和二价镁.
基金supported by the National Natural Science Foundation of China (31600766, 21473138 and 81330031)the Fundamental Research Funds for the Central Universities (No. 2682016CX076)
文摘Biodegradable magnesium（Mg）-based vascular stents have been designed as temporary scaffolds to treat angiostenotic lesions for the maintenance of normal blood flow.Numerous studies have presented in vitro and in vivo tests for the evaluation of the safety and feasibility of Mg-based vascular stents and the related materials. Therein the cytocompatibility is a basic and important parameter in the evaluation system. In this review, we summarize the applications and limitations of in vitro evaluation methods including basic characterization methods and direct and indirect cytotoxicity tests. We discuss the influencing factors on cytotoxicity, such as surface roughness, preconditioning of sample surface, cell type for the biocompatibility evaluation in direct contact as well as conditions for the formation of extracts/degradation products for indirect assays. Besides, we highlight the recent in vivo animal tests and clinical trials about Mgbased stents along with some associated results. The aim of this review is to provide a meaningful reference in the further developments and related evaluation methods of Mg-based stents.
文摘In order to provide evidence for making clinical decision, the role of intravenous and nebulized MgSO4 in treatment of adult＇s acute asthma was systematically estimated in the present study. Pubmed, Embase, Web of Sciences, the Cochrane Library and two Chinese literature databases （CNKI, WanFang） were systematically searched up to January 2016. Randomized controlled trails （RCTs） that compared the clinical outcomes of MgSO4 groups and placebo groups were included. The primary outcome was hospital admission. Secondary outcomes included pulmonary function, symptom scores, vital signs and adverse events. The methodological quality of the included studies was evaluated, and the forest plots with meta-analysis were drawn by RevMan 5.2. A total of 24 RCTs derived from 2931 patients were included. Both intravenous MgSO4 and nebulized MgSO4 treatments had no effect upon hospital admission （RR 0.91, 95% CI 0.80 to 1.03, P = 0.14; RR 0.78, 95% CI 0.56 to 1.08, P = 0.14）. Both intravenous MgSO4 and nebulized MgSO4 treatments were associated with significant evidence upon respiratory function （SMD 0.23, 95% CI 0.03 to 0.43, P = 0.02; SMD 0.37, 95% CI 0.11 to 0.64, P = 0.006）, but sensitivity analyses showed that outcomes were changed by omitting studies of less than 100 individuals （SMD 0.05, 95% C1-0.05 to 0.15, P = 0.35; SMD 0.05, 95% C1-0.16 to 0.25, P = 0.64）. There were no statistically significant differences in clinical symptom scores and vital signs （heart or pulse rate; systolic blood pressure; respiratory rate） in either form of MgSO4 compared with placebo groups （P〉0.05）. There were no serious adverse events reported in any literature. Overall, there was no role for intravenous and nebulized MgSO4 in the management of acute asthma in adults. Considering the low risk of serious adverse effects and easy availability, it seemed reasonable to use intravenous or nebulized MgSO4 treatment in adults with life threatening asthma in whom any potential benefit would justify the risks of treatment.
