期刊文献+
共找到22篇文章
< 1 2 >
每页显示 20 50 100
The brain activation pattern of the medial temporal lobe during chewing gum: a functional MRI study 被引量:2
1
作者 Youn-Hee Choi Woo Hyuk Jang +5 位作者 Sang-Uk Im Keun-Bae Song Hee-Kyung Lee Han Do Lee You Sung Seo Sung Ho Jang 《Neural Regeneration Research》 SCIE CAS CSCD 2017年第5期812-814,共3页
The human brain is known to be influenced by environmental stimuli(Feeney et al.,1982;Kaplan,1988).Therefore,research on the brain activation pattern by external stimuli has been an important topic in neuroscience(... The human brain is known to be influenced by environmental stimuli(Feeney et al.,1982;Kaplan,1988).Therefore,research on the brain activation pattern by external stimuli has been an important topic in neuroscience(Kaplan,1988).Chewing gum has been known to have a positive effect on cognition,including alertness,attention,cognitive processing speed, 展开更多
关键词 MRI The brain activation pattern of the medial temporal lobe during chewing gum a functional MRI study
下载PDF
A comparative investigation of an AB- and AA-stacked bilayer graphene sheet under an applied electric field:A density functional theory study 被引量:1
2
作者 汪涛 郭清 +1 位作者 刘艳 盛况 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第6期451-455,共5页
An AB-and AA-stacked bilayer graphene sheet (BLG) under an electric field is investigated by ab initio calculation. The interlayer distance between the two layers, band structures, and atomic charges of the system a... An AB-and AA-stacked bilayer graphene sheet (BLG) under an electric field is investigated by ab initio calculation. The interlayer distance between the two layers, band structures, and atomic charges of the system are investigated in the presence of different electric fields normal to the BLG. The AB-stacked BLG is able to tune the bandgap into 0.234 eV with the increase of the external electronic field to 1 V/nm, however, the AA-stacked BLG is not sensitive to the external electric field. In both the cases, the spacing between the BLG slightly change in terms of the electric field. The charges in the AB-stacked BLG are increased with the increase of the electric field, which is considered to be the reason that causes the bandgap opening in the AB-stacked BLG. 展开更多
关键词 GRAPHENE bandgap density functional theory study
下载PDF
Changes in cortical activation patterns accompanying somatosensory recovery in a stroke patient: a functional magnetic resonance imaging study 被引量:3
3
作者 Yong Hyun Kwon Mi Young Lee 《Neural Regeneration Research》 SCIE CAS CSCD 2014年第15期1485-1488,共4页
The somatosensory system plays a crucial role in executing precise movements by providing sensory feedback (Farrer et al., 2003; Rabin and Gordon, 2004). Somatosensory dys- function is a common problem following str... The somatosensory system plays a crucial role in executing precise movements by providing sensory feedback (Farrer et al., 2003; Rabin and Gordon, 2004). Somatosensory dys- function is a common problem following stroke. In partic- ular, somatosensory impairments, such as impairment in touch, proprioception, light touch, and vibration have been frequently observed (Carey et al., 1993; Sullivan and Hed- man, 2008; Tyson et al., 2008). Patients with somatosensory dysfunction show negative effects on motor control, and it sometimes becomes difficult to perform daily activities independently. 展开更多
关键词 SMA Changes in cortical activation patterns accompanying somatosensory recovery in a stroke patient a functional magnetic resonance imaging study
下载PDF
A Density Functional Study of N-Doped TiO_2 Anatase Cluster
4
作者 曹飞 谭凯 +1 位作者 林梦海 张乾二 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2009年第8期998-1002,共5页
A systematic study on geometry, electronic structure and vibrational properties of N-doped TiO2 anatase cluster, within the framework of the density functional theory, has been performed in this work. The calculations... A systematic study on geometry, electronic structure and vibrational properties of N-doped TiO2 anatase cluster, within the framework of the density functional theory, has been performed in this work. The calculations confirmed that the most structures in substitutional model consist of a two-coordinate bridge structure and a three-coordinate hollow structure. The calculated results can well explain the red shift in N-doped TiO2 observed in experiments. The study provides an illustration for the N-doped anatase from the viewpoint of chemical bonding theory. 展开更多
关键词 A Density functional study of N-Doped TiO2 Anatase Cluster N-doped TiO2 DFT HOMO-LUMO gap
下载PDF
A STUDY OF THE WAVE FUNCTION WITH SYMPLECTIC SYMMETRY^1
5
作者 Xiao Qin JIANG Jin Liang GUO Chia Chung SUN 《Chinese Chemical Letters》 SCIE CAS CSCD 1992年第7期531-532,共2页
By using the linear combination of the AGP(antisymmetrtzed geminat power) and SPG(sequential product of geminats) functions, an attempt has been made to catcutate the ground state of the LiH molecule. The calculated r... By using the linear combination of the AGP(antisymmetrtzed geminat power) and SPG(sequential product of geminats) functions, an attempt has been made to catcutate the ground state of the LiH molecule. The calculated results show that-the AGP or SPG function gives the same ground state result as their linear combination. 展开更多
关键词 AGP A study OF THE WAVE function WITH SYMPLECTIC SYMMETRY~1
下载PDF
The function genomics study
6
作者 HUANG Hai Shanghai Plant Physiology Inst,the Chinese Academy of Sciences,Shanghai 200032 LI Nantian CNRRI Hangzhou 310006,China 《Chinese Rice Research Newsletter》 2001年第1期14-15,共2页
Genomics is a biology term appeared ten years ago, used todescribe the researches of genomic mapping, sequencing,and structure analysis, etc. Genomics, the first journal forpublishing papers on genomics research was b... Genomics is a biology term appeared ten years ago, used todescribe the researches of genomic mapping, sequencing,and structure analysis, etc. Genomics, the first journal forpublishing papers on genomics research was born in 1986.In the past decade, the concept of genomics has beenwidely accepted by scientists who are engaging in biologyresearch. Meanwhile, the research scope of genomics hasbeen extended continuously, from simple gene mappingand sequencing to function genomics study. To reflect thechange, genomics is divided into two parts now, thestructure genomics and the function genomics.Structure genomics retains the primary research con-tent of genomics, such as constructing high density genetic 展开更多
关键词 GENE The function genomics study HIGH
下载PDF
A comparative study of pancreatic endocrine function and related metabolism after long-term survival between the patients with combined kidneypancreas transplantation vs those with combined en bloc ' liver-pancreas transplantation
7
作者 朱晓峰 《外科研究与新技术》 2011年第4期292-292,共1页
Objective To compare the effects of combined en bloc liver - pancreas transplantation ( LPT) with portal vein drainage and simultaneous combined kidney - pancreas transplantation ( KPT) with systemic venous drainage o... Objective To compare the effects of combined en bloc liver - pancreas transplantation ( LPT) with portal vein drainage and simultaneous combined kidney - pancreas transplantation ( KPT) with systemic venous drainage on the pancreatic endocrine function and related me- 展开更多
关键词 LPT A comparative study of pancreatic endocrine function and related metabolism after long-term survival between the patients with combined kidneypancreas transplantation vs those with combined en bloc liver-pancreas transplantation KPT
下载PDF
Ultra-incompressible Ternary Diborides Re_(0.5)Ir_(0.5)B_2,Re_(0.5)Tc_(0.5)B_2,Os_(0.5)W_(0.5)B_2 and Os_(0.5)Ru_(0.5)B_2:Density Functional Calculation
8
作者 林霏 吴克琛 +3 位作者 和建刚 洒荣建 李巧红 韦永勤 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2011年第5期622-629,共8页
In this paper, density functional computations have been applied to the structural, elastic and electronic properties of ternary transition metal diborides Re0.5Ir0.5B2, Re0.5Tc0.5B2, Os0.5W0.5B2 and Os0.5Ru0.5B2 in h... In this paper, density functional computations have been applied to the structural, elastic and electronic properties of ternary transition metal diborides Re0.5Ir0.5B2, Re0.5Tc0.5B2, Os0.5W0.5B2 and Os0.5Ru0.5B2 in hexagonal (P63/mmc) and orthorhombic (Pmmn) structures with both local density approximation and generalized gradient approximation. LDA gives smaller lattice parameters and larger elastic moduli than GGA. Both results show that the hexagonal ones are more stable than orthorhombic ones except Os0.5Ru0.5B2. Moreover, the hexagonal structure has superior elastic property than orthorhombic one. Generally speaking, the calculated elastic moduli of Re0.5Ir0.5B2 and Os0.5Ru0.5B2 are smaller than those values of Re0.5Tc0.5B2 and Os0.5W0.5B2 within the same structure because of the filling of antibonding states. The relativistic effects result in weaker bonds of Tc-B (Ru-B) than those of Re-B (Os-B). All the diborides are ultra-incompressible. Re0.5Tc0.5B2 has the largest shear modulus and it is a promising superhard diboride like Os0.5W0.5B2. The elastic properties are in high correlation with the bond strength. The shear moduli are more sensitive than the bulk moduli to the bond strength. 展开更多
关键词 transition metal borides elastic moduli density functional study ultra-incompressible
下载PDF
A callus transformation system for gene functional studies in soybean
9
作者 XU Kun ZHANG Xiao-mei +5 位作者 FAN Cheng-ming CHEN Fu-lu ZHU Jin-long ZHANG Shi-long CHEN Qing-shan FU Yong-fu 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2017年第9期1913-1922,共10页
Obtaining transgenic plants is a common method for analyzing gene function. Unfortunately, stable genetic transformation is difficult to achieve, especially for plants(e.g., soybean), which are recalcitrant to genet... Obtaining transgenic plants is a common method for analyzing gene function. Unfortunately, stable genetic transformation is difficult to achieve, especially for plants(e.g., soybean), which are recalcitrant to genetic transformation. Transient expression systems, such as Arabidopsis protoplast, Nicotiana leaves, and onion bulb leaves are widely used for gene functional studies. A simple method for obtaining transgenic soybean callus tissues was reported recently. We extend this system with simplified culture conditions to gene functional studies, including promoter analysis, expression and subcellular localization of the target protein, and protein-protein interaction. We also evaluate the plasticity of this system with soybean varieties, different vector constructs, and various Agrobacterium strains. The results indicated that the callus transformation system is efficient and adaptable for gene functional investigation in soybean genotype-, vector-, and Agrobacterium strain-independent modes. We demonstrated an easy set-up and practical homologous strategy for soybean gene functional studies. 展开更多
关键词 soybean callus gene function studies transformation
下载PDF
A comparative study on three EOF analysis techniques using decades of Arctic sea-ice concentration data
10
作者 陈新保 刘信陶 +1 位作者 李松年 Chow Annie 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第7期2681-2690,共10页
Change in Arctic sea ice extent is one of the indicators of global climate changes. Spatio-temporal change and change patterns can be identified using various methods to facilitate human understanding global climate c... Change in Arctic sea ice extent is one of the indicators of global climate changes. Spatio-temporal change and change patterns can be identified using various methods to facilitate human understanding global climate changes. Three empirical orthogonal function(EOF) techniques are discussed and applied to decades of sea-ice concentration(SIC) dataset in Arctic area for identifying independent patterns. It was found that: 1) discrepancies exist in magnitude and scope for each EOF pattern, however, the first two leading EOFs of variability possess high similarities in structure and shape; 2) Even though there are somewhat differences in amplitude of each PC mode, the first two leading PC modes maintain consistent in overall trend and periodicity; 3) There are significant discrepancies and inconsistencies in the third and fourth leading EOF and PC modes. The accuracies of three techniques are further validated in representing the physical phenomena of SIC anomaly patterns. 展开更多
关键词 empirical orthogonal functions sea-ice concentration comparative study patterns arctic
下载PDF
PARACRYSTAL STRUCTURE PARAMETERS STUDIES IN LDPE/EPO BLENDS WITH VARIANCE-RANGE FUNCTION METHOD
11
作者 Huan GAO Bao Quan YANG Zhi Shen MO Changchun Institute of Applied Chemistry,Academia Sinica,Changchun,130022Zhong Cheng HU The Center of Analysis and Measurement,Northeast Normal University,Changchun 《Chinese Chemical Letters》 SCIE CAS CSCD 1991年第4期321-322,共2页
X-ray diffraction line profiles of low density polyethylene(LDPE)/ (ethylene-propylene-octene-1)copolymer(EPO)blends have been analyzed with variance range function method.Theories for determining the microparacrystal... X-ray diffraction line profiles of low density polyethylene(LDPE)/ (ethylene-propylene-octene-1)copolymer(EPO)blends have been analyzed with variance range function method.Theories for determining the microparacrystallite size and the distortion parameter from single reflection have been described,and the value of these two parameters at (110)and(200)directions have been determined. 展开更多
关键词 EPO PARACRYSTAL STRUCTURE PARAMETERS STUDIES IN LDPE/EPO BLENDS WITH VARIANCE-RANGE function METHOD LDPE
下载PDF
A rabies virus-based toolkit for efficient retrograde labeling and monosynaptic tracing 被引量:1
12
作者 Kun-Zhang Lin Lei Li +5 位作者 Wen-Yu Ma Xin Yang Zeng-Peng Han Neng-Song Luo Jie Wang Fu-Qiang Xu 《Neural Regeneration Research》 SCIE CAS CSCD 2023年第8期1827-1833,共7页
Analyzing the structure and function of the brain's neural network is critical for identifying the working principles of the brain and the mechanisms of brain diseases.Recombinant rabies viral vectors allow for th... Analyzing the structure and function of the brain's neural network is critical for identifying the working principles of the brain and the mechanisms of brain diseases.Recombinant rabies viral vectors allow for the retrograde labeling of projection neurons and cell type-specific trans-monosynaptic tracing,making these vectors powerful candidates for the dissection of synaptic inputs.Although several attenuated rabies viral vectors have been developed,their application in studies of functional networks is hindered by the long preparation cycle and low yield of these vectors.To overcome these limitations,we developed an improved production system for the rapid rescue and preparation of a high-titer CVS-N2c-ΔG virus.Our results showed that the new CVS-N2c-ΔG-based toolkit performed remarkably:(1)N2cG-coated CVS-N2c-ΔG allowed for efficient retrograde access to projection neurons that were unaddressed by rAAV9-Retro,and the efficiency was six times higher than that of rAAV9-Retro;(2)the trans-monosynaptic efficiency of oG-mediated CVS-N2c-ΔG was 2–3 times higher than that of oG-mediated SAD-B19-ΔG;(3)CVS-N2c-ΔG could delivery modified genes for neural activity monitoring,and the time window during which this was maintained was 3 weeks;and(4)CVS-N2c-ΔG could express sufficient recombinases for efficient transgene recombination.These findings demonstrate that new CVS-N2c-ΔG-based toolkit may serve as a versatile tool for structural and functional studies of neural circuits. 展开更多
关键词 functional studies neural activity neural circuits projection neurons rAAV9-Retro rabies virus recombination retrograde labeling synaptic inputs trans-monosynaptic tracing
下载PDF
Cloning the full-length cDNA of a gene responsible for vascular smooth muscle cell proliferation in atherogenesis and study of function 被引量:3
13
作者 赵高峰 高鹏 +3 位作者 张华 娄黎明 乔绘红 佘铭鹏 《Chinese Medical Journal》 SCIE CAS CSCD 2003年第2期166-170,共5页
To clone the full length cDNA of a gene responsible for vascular smooth muscle cell (v SMC) proliferation in atherogenesis, and study its function Methods Oxidized low density lipoprotein (ox LDL) at optimal conc... To clone the full length cDNA of a gene responsible for vascular smooth muscle cell (v SMC) proliferation in atherogenesis, and study its function Methods Oxidized low density lipoprotein (ox LDL) at optimal concentration was used as the stimulant to induce v SMC proliferation in culture medium A cDNA subtractive library of v SMC proliferation specific to ox LDL stimulation was established using subtractive hybridization technique Methods, including blotting, Northern hybridization and gene sequencing, were used to clone new gene fragments By using full length cDNA screening and protein expression techniques, one full length cDNA was cloned and its function was studied Results One full length cDNA was cloned The new gene (Genbank AF 174647) expressed a 44 kDa protein, which might be associated with the activity of ox LDL Conclusion The new gene cloned may be associated with SMC proliferation in atherogenesis 展开更多
关键词 subtractive hybridization associated gene cDNA whole length functional study
原文传递
Health-related quality of life evaluated by tumor node metastasis staging system in patients with hepatocellular carcinoma 被引量:11
14
作者 Cui-Xia Qiao Xiao-Feng Zhai +4 位作者 Chang-Quan Ling Qing-Bo Lang Hui-Juan Dong Qun Liu Mou-Duo Li 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第21期2689-2694,共6页
AIM: To investigate and evaluate the change in healthrelated quality of life (HRQoL) by tumor node metastasis (TNM) staging system in patients with hepatocellular carcinoma (HCC). METHODS: A total of 140 patients diag... AIM: To investigate and evaluate the change in healthrelated quality of life (HRQoL) by tumor node metastasis (TNM) staging system in patients with hepatocellular carcinoma (HCC). METHODS: A total of 140 patients diagnosed with HCC between June 2008 and April 2009 in our department were enrolled to this study. One hundred and thirty-five (96.5%) patients had liver cirrhosis secondary to hepatitis B virus (HBV) infection, 73 (54.07%) of them being HBV DNA positive; the other etiologies of liver cirrhosis were alcoholic liver disease (1.4%), hepatitis C (1.4%) or cryptogenic (0.7%). All subjects were fully aware of their diagnosis and provided informed consent. HRQoL was assessed before treatment using the functional assessment of cancer therapy-hepatobiliary (FACT-Hep) questionnaire. Descriptive statistics were used to evaluate demographics and disease-specific characteristics of the patients. One-way analysis of variance and independent samples t tests were used to compare the overall FACT-Hep scores and clinically distinct TNM stages. Scores for all FACT-Hep items were analyzed by frequency analyses. The mean scores obtained from the FACT-Hep in different Child-Pugh classes were also evaluated. RESULTS: The mean FACT-Hep scores were reduced significantly from TNM StageⅠto Stage Ⅱ, Stage ⅢA, Stage ⅢB group (687 ± 39.69 vs 547 ± 42.57 vs 387 ± 51.24 vs 177 ± 71.44, P = 0.001). Regarding the physical and emotional well-being subscales, scores decreased gradually from Stage Ⅰ to Stage ⅢB (P = 0.002 vs Stage Ⅰ; P = 0.032 vs Stage Ⅱ; P = 0.033 vs Stage ⅢA). Mean FACT-Hep scores varied by Child-Pugh class, especially in the subscales of physical well-being, functional well-being and the hepatobiliary cancer (P = 0.001 vs Stage I; P = 0.036 vs Stage Ⅱ; P = 0.032 vs Stage ⅢA). For the social and family well-being subscale, only Stage ⅢB scores were significantly lower as compared with Stage Ⅰ scores (P = 0.035). For the subscales of functional well-being and hepatobiliary cancer, there were significant differences for Stages ⅡΙ, ⅢA and ⅢB (P = 0.002vs StageⅠ). CONCLUSION: HRQoL of patients with HCC worsens gradually with progression of TNM stages. The most impaired subscales of HRQoL, as measured by FACT-Hep, were physical and emotional well-being. 展开更多
关键词 Hepatocellular carcinoma Tumor node metastasis staging functional assessment of cancer therapy-hepatobiliary Health-related quality of life Cross-sectional study
下载PDF
CARDIAC FUNCTION AND HISTOLOGICAL CHANGES AFTER NON-DYNAMIC CARDIOMYOPLASTY AND PRELIMINARY STUDY OF DYNAMIC CARDIOMYOPLASTY
15
作者 马勇光 王大玫 +1 位作者 李健宁 朱洪荫 《Chinese Medical Journal》 SCIE CAS CSCD 1994年第11期38-41,共4页
By means of histological method and ultrasound cardiographic (UCG) examination, the left-right ratio of transectional area of muscle fiber of latissimus dorsi muscle (LDM) after non-dynamic cardiomyoplasty was 77.4% ?... By means of histological method and ultrasound cardiographic (UCG) examination, the left-right ratio of transectional area of muscle fiber of latissimus dorsi muscle (LDM) after non-dynamic cardiomyoplasty was 77.4% ?11.7% in GroupⅠ (3 weeks after operation), and 78.4+ 11.6% in Group Ⅱ (3 months after operation). There were muscular atrophy and hyperplasia of LDM, but the basical structure was retained. The ejection fraction (EF) decreased significantly after operation (P<0.05), but the difference between two groups was non?significant. Also, dynamic cardiomyoplasty was performed on a sheep. UCG showed the increased cardiac systolic function after operation. ATPase, succinodehydrogenase (SDH) and PAS examination implied the strengthening of fatigue-esistant ability in skeletal muscles after long-term electrical stimulation. So cardiomyoplasty is suggested to be a supplementary measure in treating end-stage heart failure. 展开更多
关键词 CARDIAC function AND HISTOLOGICAL CHANGES AFTER NON-DYNAMIC CARDIOMYOPLASTY AND PRELIMINARY study OF DYNAMIC CARDIOMYOPLASTY LDM
原文传递
The Study of Rationalization of the Economic Functions in Shanghai——the Study Group of the “Same topic”
16
作者 IrisTam H.KChan 《China City Planning Review》 1989年第1期3-23,共21页
From the PersPective of the systemsaPProaeh,the urban eeonomie functions re-fer to the role Played by the eeonomy of theeity in its surrounding areas.Beeause of different geograPhieal loeations,historiealeonditions,th... From the PersPective of the systemsaPProaeh,the urban eeonomie functions re-fer to the role Played by the eeonomy of theeity in its surrounding areas.Beeause of different geograPhieal loeations,historiealeonditions,the various roles and funetionsof the eities in the national economy,theeeonomie funetions of a eity may be of 展开更多
关键词 The study of Rationalization of the Economic functions in Shanghai the study Group of the Same topic
原文传递
A Study of the Structure and the Functions of the Local Resident Organization in China's Urbanized Society
17
作者 Liu Zhuyuan the Institute of Scientific Socialism,Central China Normal University Guo Zhiwen 《China City Planning Review》 1989年第1期39-45,共7页
To set up self-rule organizations forsocial life of the mass at city’s local level isnot uncommon in other countries.But toset up a resident committee of completestructure and with overall functions thatserves as an ... To set up self-rule organizations forsocial life of the mass at city’s local level isnot uncommon in other countries.But toset up a resident committee of completestructure and with overall functions thatserves as an intermediate between the localpolitical organization and family units issomething peculiar to China.Then。 展开更多
关键词 time area A study of the Structure and the functions of the Local Resident Organization in China’s Urbanized Society ORGANIZATION
原文传递
EFFECTS OF PARATHYROID HORMONE AND ESTRADIOL ON PROLIFERATION AND FUNCTION OF HUMAN OSTEOBLASTS FROM FETAL LONG BONE AN IN VITRO STUDY
18
作者 臧晓怡 谭郁彬 +2 位作者 庞智玲 张文治 赵杰 《Chinese Medical Journal》 SCIE CAS CSCD 1994年第8期42-45,共4页
The effect of parathyroid hormone (PTH) (0.01 nM-10 nM) and 17 -estradiol (E2, 1 nmol-10 nM) alone or in combination on 3H thymidine incorporation, alkaline phosphatase and adenylate cyclase activities were investigat... The effect of parathyroid hormone (PTH) (0.01 nM-10 nM) and 17 -estradiol (E2, 1 nmol-10 nM) alone or in combination on 3H thymidine incorporation, alkaline phosphatase and adenylate cyclase activities were investigated in human fetal osteoblasts using serum-free monolayer primary cultures. The results showed that PTH inhibited cell proliferation while E, promoted it. On alkaline phosphatase activity, PTH showed a complex results while E, were slightly inhibitory. PHT-E2 combination suggested that E2 could alter the effect of PTH alone, also potentiated the anabolic and antagonize the catabolic effects of PTH on bone formation. 展开更多
关键词 PTH 110 EFFECTS OF PARATHYROID HORMONE AND ESTRADIOL ON PROLIFERATION AND function OF HUMAN OSTEOBLASTS FROM FETAL LONG BONE AN IN VITRO study
原文传递
Theoretical study on the formation mechanism of polychlorinated dibenzothiophenes/thianthrenes from 2-chlorothiophenol molecules 被引量:1
19
作者 Xiaoqing Yu Jiamin Chang +2 位作者 Xian Liu Wenxiao Pan Aiqian Zhang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2018年第4期318-327,共10页
Homogeneous formation of polychlorinated dibenzothiophenes/thianthrenes(PCDT/TAs),sulfurated compounds analogous to polychlorinated dibenzo-p-dioxin/dibenzofurans(PCDD/Fs), has been well-documented to occur via ra... Homogeneous formation of polychlorinated dibenzothiophenes/thianthrenes(PCDT/TAs),sulfurated compounds analogous to polychlorinated dibenzo-p-dioxin/dibenzofurans(PCDD/Fs), has been well-documented to occur via radical–radical coupling reactions from chlorinated thiophenol precursors. However, the current understanding of the formation mechanism of PCDT/TAs is exclusively limited to the inherent point of view that chlorothiophenoxy radicals act as the only required intermediates for PCDT/TAs. This study investigates reaction pathways for the formation of PCDT/TAs involving two new types of radical species, i.e., substituted phenyl radicals and substituted thiophenoxyl diradicals. Taking 2-chlorothiophenol(2-CTP) as a model compound for chlorothiophenols,we found that apart from the mostly discussed chlorothiophenoxy radicals, substituted phenyl radicals and substituted thiophenoxyl diradicals could also be readily formed via the reaction of 2-CTP with H radicals. Furthermore, direct self-and cross-coupling of these radicals can result in the formation of PCDT/TAs, including 1-monochlorothianthrene(1-MCTA), 1,6-dichlorothianthrene(1,6-DCTA), 4,6-dichlorodibenzothiophene(4,6-DCDT)and 1,6-dichlorodibenzothiophene(1,6-DCDT). The pathways proposed in this work are proven to be both thermodynamically and kinetically favorable. Particularly, comparisons were made between the formation mechanisms of sulfurated and oxygenated dioxin systems from an energetic point view, showing that replacing oxygen with sulfur atoms greatly reduces the activation barriers of the rate-controlling steps involved in the PCDT/TA formation processes compared with those involved for PCDD/Fs. The calculated results in this work may improve our understanding of the formation mechanism of PCDT/TAs from chlorothiophenol precursors and should be informative to environmental scientists. 展开更多
关键词 Polychlorinated dibenzothiophenes/thianthrenes Formation mechanism Phenyl radicals Thiophenoxyl diradicals Density functional theory study
原文传递
A pH-universal ORR catalyst with atomic Fe-heteroatom(N,S)sites for high-performance Zn-air batteries 被引量:1
20
作者 Le Li Na Li +6 位作者 Jia-Wei Xia Shi-Long Zhou Xing-Yue Qian Feng-Xiang Yin Guo-Hong Dai Guang-Yu He Hai-Qun Chen 《Nano Research》 SCIE EI CSCD 2023年第7期9416-9425,共10页
Developing innovative,easy-to-manufacture,and non-Pt-group-metal(non-PGM)electrocatalysts is essential for the highly efficient oxygen reduction reaction(ORR).Herein,we report a self-sacrificing post-synthetic strateg... Developing innovative,easy-to-manufacture,and non-Pt-group-metal(non-PGM)electrocatalysts is essential for the highly efficient oxygen reduction reaction(ORR).Herein,we report a self-sacrificing post-synthetic strategy to synthesize highly loaded Fe-isolated single atoms anchored on the hierarchical porous N,S co-doped carbon matrix(Fe-SAs/S,N-C/rGO).The optimized Fe-SAs/S,N-C/rGO exhibits excellent ORR activity in the pH-universal range with half-wave potentials of 0.89,0.80,and 0.60 V in alkaline,acidic,and neutral media,comparable to the commercial Pt/C(0.85,0.81,and 0.64 V,respectively).The homemade liquid Zn-air battery(ZAB)with Fe-SAs/S,N-C/rGO as the cathode catalyst displays an open-circuit voltage(OCV)of~1.61 V,discharging specific capacity of 817.23 mAh·g^(-1),and long-term durability of~1865 cycles,outperforming those of the device with commercial Pt/C+RuO_(2)(1.49 V,657.32 mAh·g^(-1),and~120 cycles,respectively).Intriguingly,the corresponding flexible solidstate ZAB delivers satisfactory OCV,peak power density,foldability,and cycling stability at room temperature,as well as adaptability at a low temperature of -10℃.Besides,density functional theory(DFT)calculation reveals that the atomic FeN_(3)S moieties in Fe-SAs/S,N-C/rGO can cause charge redistribution and lower the binding strength of oxygen-containing intermediates,resulting in accelerated ORR kinetics and optimized catalytic activity.This work provides insights into experimental and theoretical guidance towards non-PGM electrocatalysts for efficient energy conversion. 展开更多
关键词 heteroatom dopant single-atom electrocatalyst FeN_(3)S sites Zn-air battery density functional theory(DFT)study
原文传递
上一页 1 2 下一页 到第
使用帮助 返回顶部