检索结果-南通市图书馆

Dual response of graphene-based ultra-small molecular junctions to defect engineering

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2016年第5期9卷 1480-1488页

作者： Kunpeng Dou Xiaoxiao Fu Abir De Sarkar ruiqin zhang Department of Physics and Materials Science City University of Hong Kong Hong Kong China Institute of Nano Science and Technology (An Autonomous Institute of Department of Science and Technology Government of India)Habitat Centre (Transit Campus) Phase X Sector-64 Mohali Punjab- 160 062 India

It has been reported that N and B doping induce a quasi-bound state that suppresses the conduction in graphene nanoribbon （GNR）-based junctions, while an H defect or a pyridine-like N-atom （PN） substitution at the edge of the GNR does not affect the transmission close to the Fermi energy. However, these results may vary when the size of the functional unit of the GNR junction decreases to a molecular level. In this study, a defect is introduced to a test-bed architecture consisting of a polyacene bridging two zigzag GNR electrodes, which changes the molecular state alignment and coupling to the electrode states, and varies the equivalence between two eigen-channels at the Fermi level. It is revealed that B and N atom substitution, and H defects play a dual role in the molecular conductance, whereas the PN substitution acts as an ineffective dopant. The results obtained from density functional theory combined with the non-equilibrium Green＇s function method aid in determining the optimal design for the GNR-based ultra-small molecular devices via defect engineering.

关键词： graphene defect electron transport molecular electronics single-molecule studies

Characteristics,sources and health risks assessment of VOCs in Zhengzhou,China during haze pollution season

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2021年第10期33卷 44-57页

作者： Dong zhang Bing He Minghao Yuan Shijie Yu Shasha Yin ruiqin zhang College of Chemistry Zhengzhou UniversityZhengzhou 450001China Institute of Environmental Sciences Zhengzhou UniversityZhengzhou 450001China School of Ecology and Environment Zhengzhou UniversityZhengzhou 450001China Environmental Protection Monitoring Center Station of Zhengzhou Zhengzhou 450007China

Zhengzhou is one of the most haze-polluted cities in Central China with high organic carbon emission,which accounts for 15%-20%of particulate matter(PM_(2.5))in winter and causes significantly adverse health *** organic compounds(VOCs)are the precursors of secondary PM_(2.5)and O_(3)*** investigation of characteristics,sources and health risks assessment of VOCs was carried out at the urban area of Zhengzhou from 1^(st) to 31^(st) December,*** mean concentrations of total detected VOCs were 48.8±23.0 ***(22.0±10.4 ppbv),halocarbons(8.1±3.9 ppbv)and aromatics(6.5±3.9 ppbv)were the predominant VOC species,followed by alkenes(5.1±3.3 ppbv),oxygenated VOCs(3.6±1.8 ppbv),alkyne(3.5±1.9,ppbv)and sulfide(0.5±0.9 ppbv).The Positive Matrix Factorization model was used to identify and apportion VOCs *** major sources of VOCs were identified as vehicular exhaust,industrial processes,combustion,fuel evaporation,and solvent *** carcinogenic and non-carcinogenic risk values of species were *** carcinogenic and non-carcinogenic risks of almost all air toxics increased during haze *** total non-carcinogenic risks exceeded the acceptable *** VOC species posed no non-carcinogenic risk during three haze *** carcinogenic risks of chloroform,1,2-dichloroethane,1,2-dibromoethane,benzyl chloride,hexachloro-1,3-butadiene,benzene and naphthalene were above the acceptable level(1.0×10^(-6))but below the tolerable risk level(1.0×10^(-4)).Industrial emission was the major contributor to non-carcinogenic,and solvent use was the major contributor to carcinogenic risks.

关键词： Zhengzhou Positive Matrix Factorization Health risks VOC profiles

Spatiotemporal characterization and regional contributions of O3 and NO2:An investigation of two years of monitoring data in Henan,China

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2020年第4期32卷 29-40页

作者： Shijie Yu Shasha Yin ruiqin zhang Lingling Wang Fangcheng Su Yixiang zhang Jian Yang Research Institute of Environmental Science College of Chemistry and Molecular EngineeringZhengzhou UniversityZhengzhou450001China Henan Environment Monitoring Centre Zhengzhou450004China

To investigate the characteristics of ground level ozone(O3)for Henan Province,the ambient air quality monitoring data of 2015 and 2016 were *** result showed that the 8 h-max-O3 concentrations displayed a distinct seasonality,where the maximum and minimum values,averaging 140.41,54.19μg/m3,occurred in summer and winter,*** is a significant correlation between meteorological factors and O3 *** Voronoi neighborhood averaging analysis indic ated that O3,temperature,and ultraviolet radiation in Henan province were decreased from northwest to southeast,while relative humidity and precipitation displayed the opposite *** meteorological factors,the chemical processes play an essential role in ozone *** of NO,NO2 and O3 form a closed system,and the partitioning point of the OX-component(O3+NO2)was at 40 and 80μg/m3 for nitrogen oxide(NOx)in winter and summer,respectively,with NO2 dominating at higher NOx pollution and O3 being the m ajor component at lower *** relationship between oxidant(OX=O3+NO2)and NOx concentrations were evaluated to understand the regional and local contribution of *** showed that high regional contribution occurred in the spring,whereas the highest local contribution lead to the summer peak of O3 observed in *** present study reveals important environment impacts from the photochemical process and the meteorological conditions in the region with better understanding on the O3 characterization.

关键词： Ground-level ozone Meteorological parameter Photochemical oxidant Voronoi neighborhood averaging(VNA) Seasonal variation

Remarkable Thermal Contraction in Small Size Single-Walled Boron Nanotubes

在线全文

学校读者我要写书评

暂无评论

Communications in Computational Physics 2014年第6期16卷 201-212页

作者： Xianhu Zha Shuang Li ruiqin zhang Zijing Lin Department of Physics&Collaborative Innovation Center of Suzhou Nano Science and Technology University of Science and Technology of ChinaHefei 230026China. Department of Physics and Materials Science City University of Hong KongKowloon TongHong Kong. USTC-CityU Joint Advanced Research Centre Suzhou 215123China. Nano Structured Materials Center Nanjing University of Science and TechnologyNanjing 210094China.

Density functional theory combined with the Gr¨uneisen approximation is used to calculate the thermal properties of single-walled boron nanotubes(BNTs).The specific heat and thermal expansion are *** thermal expansion coeffi-cient of the BNT is found to be significantly correlated with tube size and chirality.A remarkable thermal contraction is found at small tube *** results indicate that BNTs would have potential applications in sensors,actuators,and memory materials.

关键词： Density functional theory Gruneisen approximation single-walled boron nanotubes remarkable thermal contraction.

Abundance and sources of particulate polycyclic aromatic hydrocarbons and aromatic acids at an urban site in central China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第8期142卷 155-168页

作者： Luqi Shang Zhe Dong Zihan Li Mingkai Wang Zihan Kong Xiao Li ruiqin zhang School of Ecology and Environment Zhengzhou UniversityZhengzhou 450001China College of Chemistry Zhengzhou UniversityZhengzhou 450001China Institute of Environmental Sciences Zhengzhou UniversityZhengzhou 450001China

We conducted a simultaneous field study of PM_(2.5)-bound particulate polycyclic aromatic hydrocarbons(PAHs)and aromatic acids(AAs)in a polluted city Zhengzhou to explore the concentration,sources and potential conversion pathways between PAHs and AAs in different *** average concentrations of PM_(2.5),28PAHs and 8AAs during the sampling period were 77μg/m^(3),75 ng/m^(3),and 283 ng/m^(3),*** concentration of both28PAHs and 8AAs were highest in winter and lowest in summer with ratios of 6.3 and 2.3,*** with 5-7 rings were the main components of PAHs(52%),followed by 4rings PAHs(30%)and 2-3 rings PAHs(18%).According to the source appointment results obtained by positive matrix factorization,the main sources of PAHs were combustion and vehicle emissions,which account for 37%and 34%,respectively.8AAs were divided into three groups,including four benzene dicarboxylic acids(B2CAs),three benzene tricarboxylic acids(B3CAs)and one benzene tetracarboxylic acid(B4CA).And interspecies correlation analysis with PM_(2.5)source markers were used to investigate potential *** acid(o-Ph)was the most abundant specie of 8AAs(157 ng/m^(3),55%of 8AAs),which was well correlated with ***,B3CAs and B4CA were highly correlated with sulfate and weakly correlated with levoglucosan,suggesting that secondary formation was their main *** logical oxidation products of PAHs,o-Ph and B3CAs showed good correlations with a number of PAHs,indicating possible photochemical oxidation pathway by *** addition,O_(3),NO_(2),temperature and relative humidity have positive effects on the secondary formation of B3CAs.

关键词： Polycyclic aromatic hydrocarbons Aromatic acids Source appointment Secondary formation

PM_(2.5) in an industrial district of Zhengzhou,China:Chemical composition and source apportionment

在线全文

学校读者我要写书评

暂无评论

Particuology 2013年第1期11卷 99-109页

作者： Ningbo Geng Jia Wang Yifei Xu Wending zhang Chun Chen ruiqin zhang Research Institute of Environmental Science Department of ChemistryZhengzhou University Henan Environmental Monitoring Center

Zhengzhou is a developing city in China, that is heavily polluted by high levels of particulate matter. In this study, fine particulate matter （PM2.5） was collected and analyzed for their chemical composition （soluble ions, elements, elemental carbon （EC） and organic carbon （OC）） in an industrial district of Zhengzhou in 2010. The average concentrations of PM2.5 were 181, 122, 186 and 211 μg/m3 for spring, summer, autumn and winter, respectively, with an annual average of 175 μg/m3, far exceeding the PM2.5 regulation of USA National Air Quality Standards （15 μg/m3）. The dominant components of PM2.5 in Zhengzhou were secondary ions （sulphate and nitrate） and carbon fractions. Soluble ions, total carbon and elements contributed 41%, 13% and 3% of PM2.5 mass, respectively. Soil dust, secondary aerosol and coal combustion, each contributing about 26%, 24% and 23% of total PM2.5 mass, were the major sources of PM2.5, according to the result of positive matrix factorization analysis. A mixed source of biomass burning, oil combustion and incineration contributed 13% of PM2.5. Fine particulate matter arising from vehicles and industry contributed about 10% and 4% of PM2.5, respectively.

关键词： PM2.5 Component Seasonal variation PMF Source apportionment

Recent development of a refined multiple air pollutant emission inventory of vehicles in the Central Plains of China

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2019年第10期31卷 80-96页

作者： Xingke Gu Shasha Yin Xuan Lu Huan zhang Lingling Wang Ling Bai Chen Wang ruiqin zhang Minghao Yuan Research Institute of Environmental Science College of Chemistry and Molecular Engineering Zhengzhou University Zhengzhou 450001China Henan Environmental Monitoring Center Zhengzhou 450004 China Environmental Protection Monitoring Center Station of Zhengzhou Zhengzhou 450007 China

Central Plains region of China,represented by Henan Province,is facing serious air pollution *** exhaust emissions had adverse impacts on the atmospheric *** first comprehensive and novel vehicle emission inventory for Henan Province using vehicle kilometers traveled,localized emission factors,and activity data at city-level was ***,3 km×3 km gridded emission and temporal variations were determined by using localized *** show that the total emissions of sulfur dioxide(SO2),nitrogen oxides(NOx),carbon monoxide(CO),particular matter with aerodynamic diameter<10μm(PM10),aerodynamic diameter<2.5μm(PM2.5),volatile organic compounds(VOCs),VOCs-evaporation and ammonia in 2015 were 9.1,533.4,1190.7,23.7,21.6,150.8,31.5 and 10.4 Gg,respectively,and the emission intensities of the above pollutants were 0.05,2.7,6.0,0.1,0.1,0.8,0.2 and 0.05 g/km,*** meeting the Primary China 1,China 3 and China 4 contributed 89.1%,82.7%,75.3%,75.5%,75.5%,68.2%,68.4%and 82.3%for SO2,NOx,CO,PM10,PM2.5,VOCs,VOCs-evaporation and ammonia emissions,***,Zhoukou,Nanyang,Luoyang,Shangqiu and Xinyang showed relatively higher emissions and contributed more than 50%of each *** spatial distribution indicated obvious characteristics of the road network,and high-level emission was concentrated in the downtown ***,the ozone formation potential(OFP)based on the estimated speciated VOC emissions was 569.6 Gg in Henan *** and aromatic hydrocarbons were the main species of VOCs,whereas olefins contributed the largest proportion of OFP,with 42.2%.

关键词： Vehicle Emission standard Gridded allocation Ozone formation potential Speciated volatile organic compounds

Selective electrophilic di- and monofluorinations for the synthesis of 4-difluoromethyl and 4-fluoromethyl quinazolin(thi)ones by a Selectfluor-triggered multi-component reaction

在线全文

学校读者我要写书评

暂无评论

Organic Chemistry Frontiers 2022年第6期9卷 1567-1573页

作者： ruiqin zhang Renchao Ma Qinjiao Fu Rener Chen Zhiming Wang Lei Wang Yongmin Ma Institute of Advanced Studies and School of Pharmaceutical and Chemical Engineering Taizhou UniversityJiaojiangZhejiang318000P.R.China School of Pharmaceutical Science Zhejiang Chinese Medical UniversityHangzhou310053P R China

A simple and efficient domino protocol for the selective synthesis of 4-difluoromethyl and 4-fluoromethylquinazolin(thi)ones was established from readily available 2-aminoacetophenones and iso(thio)cyanatesmediated by Selectfluor. The reaction outcomes are restricted by the reaction environment. Without theuse of a base, gem-difluoro-oxylated quinazolin(thi)ones were afforded effectively as a sole product. Incontrast, only monofluoro-oxylated analogues were obtained under basic conditions.

关键词： conditions product synthesis

Chemical characteristics and source apportionment of PM_(2.5) between heavily polluted days and other days in Zhengzhou, China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2018年第4期30卷 188-198页

作者： Nan Jiang Qiang Li Fangcheng Su Qun Wang Xue Yu Panru Kang ruiqin zhang Xiaoyan Tang Research Institute of Environmental Science College of Chemistry and Molecular Engineering Zhengzhou University

PM（2.5） samples were collected in Zhengzhou during 3 years of observation, and chemical characteristics and source contribution were analyzed. Approximately 96% of the daily PM（2.5） concentrations and annual average values exceeded the Chinese National Ambient Air Quality Daily and Annual Standards, indicating serious PM（2.5） pollution. The average concentration of water-soluble inorganic ions was 2.4 times higher in heavily polluted days（daily PM32.5 concentrations ＆gt; 250 μg/mand visibility ＆lt; 3 km） than that in other days, with sulfate, nitrate, and ammonium as major ions. According to the ratio of NO-3/SO2-4,stationary sources are still the dominant source of PM（2.5） and vehicle emission could not be ignored. The ratio of secondary organic carbon to organic carbon indicated that photochemical reactivity in heavily polluted days was more intense than in other *** elements were the most abundant elements, accounting for more than 60% of 23 elements. Chemical Mass Balance results indicated that the contributions of major sources（i.e., nitrate, sulfate, biomass, carbon and refractory material, coal combustion, soil dust,vehicle, and industry） of PM（2.5） were 13%, 16%, 12%, 2%, 14%, 8%, 7%, and 8% in heavily polluted days and 20%, 18%, 9%, 2%, 27%, 14%, 15%, and 9% in other days, *** combustion activities were the main sources of polycyclic aromatic hydrocarbons during the episode（Jan 1-9, 2015） and the total benzo[a]pyrene equivalency concentrations in heavily polluted days present significant health threat. Because of the effect of regional transport, the pollution level of PM（2.5） in the study area was aggravated.

关键词： PM2.5 Water soluble inorganic ions Secondary organic carbon CMB Back trajectory analysis