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42篇 您的检索式:作者名="Yunfa Chen"
    题名 作者 年代 出处 被引量
1Extraction of scandium from red mud by modified activated carbon and kinetics study显示文摘激活的碳(交流) 被 tri 丁基磷酸盐(TBP ) 为有选择地从红泥提取钪修改并且由赌注(Brunauer-Emmett-Teller ) 表面区域描绘了。修改交流有优先的吸附到钪。到钪的吸附能力和选择上的吸附物剂量,吸附温度,和时间的影响被检验。最佳吸附物剂量(6.25 g/L ) ,吸附温度(308 K ) ,和吸附时间(40 min ) 被弄明白。一个 pseudo-second-order 动力学模特儿为描述钪的吸附过程被雇用。ZHOU Hualei LI Dongyan TIAN Yajun CHEN Yunfa 2008Rare Metals2008,27,3:20
2Catalytic oxidation of benzene over Ce-Mn oxides synthesized by flame spray pyrolysis显示文摘Flame spray pyrolysis(FSP) was utilized to synthesize Ce-Mn oxides in one step for catalytic oxidation of benzene.Cerium acetate and manganese acetate were used as precursors.The materials synthesized were characterized using X-ray diffraction(XRD),N_2 adsorption,X-ray photoelectron spectroscopy(XPS).transmission electron microscopy(TEM),Raman spectroscopy,and Fh-temperature programmed reduction(H_2-TPR) and their benzene catalytic oxidation behavior was evaluated.Mn ions were evidenced in multiple chemical states.Crystalline Ce-Mn oxides consist of particles with size <40 nm and specific surface areas(SSA) of 20-50m^2/g.Raman spectrums and H_2-TPR results indicated the interaction between cerium and manganese oxides.Flame-made 12.5%-Ce-Mn oxide exhibited excellent catalytic activity at relatively low temperatures(T95 about 260 C) compared to other Ce-Mn oxides with different ceriumto-manganese ratios.Redox mechanism and strong interaction conform to structure analysis that Ce-Mn strong interaction formed during the high temperature flame process and the results were used to explain catalytic oxidation of benzene.Gang Liu Renliang Yue Yi Jia Yong Ni Jie Yang Haidi Liu Zhen Wang Xiaofeng Wu Yunfa Chen 2013Particuology2013,11,4:17
3Early Pleistocene hominid teeth recovered in Mohui cave in Bubing Basin, Guangxi, South China显示文摘Two hominid teeth recovered in Mohui cave are morphologically distinguished from Australopithecus in Af-rica, but close to Homo erectus in China. These teeth are therefore provisionally assigned to Homo erectus. The associ-ated mammalian fauna include Gigantopithecus blacki, Nes-toritherium sp., Sus xiaozhu, Sus peii and Ailuropoda microta, which are typical early Pleistocene taxa in South China. The general characteristics of the Mohui faunal assemblage are similar to the Longgupo site, which is dated to 2 Ma, imply-ing a contemporaneity for the two sites. To date, compared with the discoveries in Africa, far fewer early Pleistocene hominid fossils have been recovered in Asia, and there are intensive controversies concerning their stratigraphic prove-nience and typological and temporal positions. The hominid fossils from Mohui cave, with their reliable biostratigraphic positions and distinct typological features, provide important evidence regarding the issue of early human origins and evo-lution.WANG Wei Richard Potts HOU Yamei CHEN Yunfa WU Huaying YUAN Baoyin HUANG Weiwen 2005Chinese Science Bulletin2005,50,23:8
4Effects of cerium incorporation on the catalytic oxidation of benzene over flame-made perovskite La_(1-x)Ce_xMnO_3 catalysts显示文摘Perovskite-type La_(1-x)Ce_xMnO_3(x = 0-10%) catalysts were prepared by flame spray pyrolysis and their activities during the catalytic oxidation of benzene were examined over the temperature range of100-450℃.The structural properties and reducibility of these materials were also characterized by X-ray diffraction(XRD),N_2 adsorption/desorption,H_2 temperature-programmed reduction(H_2-TPR) and X-ray photoelectron spectroscopy(XPS).The incorporation of Ce was found to improve the benzene oxidation activity,and the perovskite in which x was 0.1 exhibited the highest activity.Phase composition and surface elemental analyses indicated that non-stoichiometric compounds were present.The incorporation of Ce had a negligible effect on the specific surface area of the perovskites and hence this factor has little impact on the catalytic activity.Introduction of Ce4^(4+) resulted in modification of the chemical states of both B-site ions and oxygen species and facilitated the reducibility of the perovskite.The surface Mn^(4+)/Mn^(3+)ratio was increased as a result of Ce^(4+) substitution,while a decrease in the surface-adsorbed O/lattice O(O_(ads)/O_(latt)) ratio was observed.The relationship between the surface elemental ratios and catalytic activity was established to allow a better understanding of the process by which benzene is oxidized over perovskites.Gang Liu Jiaqi Li Kun Yang Wenxiang Tang Haidi Liu Jun Yang Renliang Yue Yunfa Chen 2015Particuology2015,13,2:6
5Effect of acidic surface functional groups on Cr(Ⅵ) removal by activated carbon from aqueous solution显示文摘The activated carbon with high surface area was prepared by KOH activation.It was further modified by H2SO4 and HNO3 to introduce more surface functional groups.The pore structure of the activated carbons before and after modification was analyzed based on the nitrogen adsorption isotherms.The morphology of those activated carbons was characterized using scanning electronic microscopy (SEM).The surface functional groups were determined by Fourier transform infrared spectroscopy (FTIR).The quantity of those groups was measured by the Boehm titration method.Cr(VI) removal by the activated carbons from aqueous solution was investigated at different pH values.The results show that compared with H2SO4,HNO3 destructs the original pore of the activated carbon more seriously and induces more acidic surface functional groups on the activated carbon.The pH value of the solution plays a key role in the Cr(VI) removal.The ability of reducing Cr(VI) to Cr(III) by the activated carbons is relative to the acidic surface functional groups.At higher pH values,the Cr(VI) removal ratio is improved by increasing the acidic surface functional groups of the activated carbons.At lower pH values,however,the acidic surface functional groups almost have no effect on the Cr(VI) removal by the activated carbon from aqueous solution.ZHOU Hualei CHEN Yunfa 2010Rare Metals2010,29,3:6
6Isolation and characterization of class Ⅰ MHC genes in the giant panda(Ailuropoda melanoleuca)显示文摘Artificial breeding is an important project to protect,recover and reintroduce endangered species.Knowledge of the population's genetic diversity at functional loci is important for the establishment of effective captive breeding programs.The major histocompatibility complex(MHC) genes are ideal candidate genetic markers to inform planned breeding,due to their high levels of polymorphism and importance in the main immune coding region of the vertebrate genome.In this study,we constructed BAC-based contigs and isolated six functional MHC class Ⅰ genes from the giant panda(Ailuropoda melanoleuca),which we designated Aime-C,Aime-F,Aime-I,Aime-K,Aime-L and Aime-1906.Analyses of the tissue expression patterns and full-length cDNA sequences of these class I genes revealed that Aime-C,-F,-I and-L could be considered classical class Ⅰ loci,due to their extensive expression patterns and normal exonic structures.In contrast,Aime-K and-1906 appeared to be nonclassical genes based on their tissue-specific expression patterns and the presence of an abnormal exon 7 in both genes.We established techniques for genotyping exons 2 and 3 of the classical loci using locus-specific single strand conformation polymorphism(SSCP) and sequence analysis.In the Chengdu captive population,we identified one monomorphic locus(Aime-F) and three polymorphic loci with different numbers of alleles(4/4/4 exon 2 alleles at Aime-C/I/L and 6/5/5 exon 3 alleles at Aime-C/I/L).The distributions of the Aime-C,-I and-L alleles among members of different families were in good agreement with the known pedigree relationships,suggesting that the genotyping results are reliable.Therefore,the MHC-I genotyping techniques established in this study may provide a powerful tool for the future design of scientific breeding or release/reintroduction programs.ZHU Ying SUN DanDan GE YunFa YU Bin CHEN YiYan WAN QiuHong 2013Chinese Science Bulletin2013,58,17:5
7Preparation and electrochemical performance of carbon-coated LiFePO4/LiMnPO4-positive material for a Li-ion battery显示文摘Qiangqiang Tan Bo Yan Yuxing Xu Yunfa Chen Jun Yang 2017Particuology2017,15,1:5
8Safety and feasibility of transulnar versus transradial artery approach for coronary catheterization in non-selective patients显示文摘Geng Wei Fu Xianghua Gu Xinshun Jiang Yunfa Fan Weize Wang Yanbo Li Wei Xing Kun Liu Chen 2014Chinese Medical Journal2014,,7:5
9Large-scale synthesis of hierarchical MnO_2 for benzene catalytic oxidation显示文摘Hierarchical sea-urchin-shaped manganese oxide microspheres were synthesized via a tacile metnoa based on the reaction between KMnO_4 and MnSO_4 in HNO_3 solution at 50 C.The average diameter of the microspheres is ~850 nm.The microspheres consist of a core of diameter of ~800 nm and nanorods of width ~50 nm.The nanorods exist at the edge of the core.The Brunauer-Emmett-Teller surface area of the sea-urchin-shaped microspheres is 259.4 m^2/g.A possible formation mechanism of the hierarchical sea-urchin-shaped microspheres is proposed.The temperature for 90%conversion of benzene(T_(90)%) on the hierarchical urchin-shaped MnO_2 microspheres is about 218℃.Dongyan Li Genli Shen Wenxiang Tang Haidi Liu Yunfa Chen 2014Particuology2014,12,3:4
10Macroporous Ni foam-supported Co_3O_4 nanobrush and nanomace hybrid arrays for high-efficiency CO oxidation显示文摘Herein, we reported the synthesis of well-defined Co_3O_4 nanoarrays(NAs) supported on a monolithic three-dimensional macroporous nickel(Ni) foam substrate for use in highefficiency CO oxidation. The monolithic Co_3O_4 NAs catalysts were obtained through a generic hydrothermal synthesis route with subsequent calcination. By controlling the reaction time,solvent polarity and deposition agent, these Co_3O_4 NAs catalysts exhibited various novel morphologies(single or hybrid arrays), whose physicochemical properties were further characterized by using several analytical techniques. Based on the catalytic and characterization analyses, it was found that the Co_3O_4 NAs-6 catalyst with nanobrush and nanomace arrays displayed enhanced catalytic activity for CO oxidation, achieving an efficient 100% CO oxidation conversion at a gas hourly space velocity(GHSV) 10,000 hr^(-1) and 150°C with longterm stability. Compared with the other Co_3O_4 NAs catalysts, it had the highest abundance of surface-adsorbed oxygen species, excellent low-temperature reducibility and was rich in surface-active sites(Co^(3+)/Co^(2+)= 1.26).Shengpeng Mo Hui He Quanming Ren Shuangde Li Weixia Zhang Mingli Fu Limin Chen Junliang Wu Yunfa Chen Daiqi Ye 2019Journal of Environmental Sciences2019,31,1:4
11Design and synthesis of porous non-noble metal oxides for catalytic removal of VOCs显示文摘The design and synthesis of highly active non-noble metal oxide catalysts, such as transition- and rare-earth-metal oxides, have attracted significant attention because of their high efficiency and low cost and the resultant potential applications for the degradation of volatile organic compounds(VOCs). The structure-activity relationships have been well-studied and used to facilitate design of the structure and composition of highly active catalysts. Recently, non-noble metal oxides with porous structures have been used as catalysts for deep oxidation of VOCs, such as aromatic hydrocarbons, aliphatic compounds, aldehydes, and alcohols, with comparable activities to their noble metal counterparts. This review summarizes the growing literature regarding the use of porous metal oxides for the catalytic removal of VOCs, with emphasis on design of the composition and structure and typical synthetic technologies.Wenxiang Tang Gang Liu Dongyan Li Haidi Liu Xiaofeng Wu Ning Han Yunfa Chen 2015Science China Chemistry2015,58,9:4
12Long-term Dynamics of Cultivated Land Resources and Their Driving Forces of Guyuan City in Upper Reaches of Jinghe River显示文摘The land use patterns in Guyuan City,Ningxia Hui Autonomous Region of China,have changed greatly over the years,due to population growth and farming and stock raising development.This study,using 50-year statis-tical data of cultivated land and 14-year spatial data of land use pattern,analyzed the developmental stages,the char-acter,and the spatial variance of farmland in the city,and discussed the driving forces of cultivated land changes based on empirical and conceptual statistical models.First,the change of cultivated land area went through different stages of rapid increase,fluctuating change,decrease and rapid decrease from 1949 to 2004,additionally,social and economic policies in different stages had an important impact on farmland variance.Second,from 1986 to 2000,the quantity of cultivated land increased,but its quality decreased.Third,social and economic factors are determinant factors in culti-vated land transition.Five constructed paths explain cultivated land transition.Factors that have direct or indirect ef-fects on farmland include the economy(Xeco),the population(Xpop),agricultural output(Xagr),and scientific input(Xsci).The sequence of impact was Xeco>Xpop>Xsci>Xagr.Among all these impacts,Xeco was the major positive one,and Xpop was the major negative one.It is urgent to take measures or adopt a policy to stop the vicious cycle in eco-environment and agriculture production.Otherwise,negative patterns of farmland use will increase,and high-quality cultivated land will continue to decline.CHEN Caocao XIE Gaodi ZHEN Lin LENG Yunfa 2008Chinese Geographical Science2008,18,1:3
13Design and fabrication of 1-D semiconductor nanomaterials for high-performance photovoltaics显示文摘To date, the cost-effective utilization of solar energy by photovoltaics for large-scale deployment remains challenging. Further cost minimization and efficiency maximization, through reduction of material consumption, simplification of device fabrication as well as optimization of device structure and geometry, are required. The usage of 1D nanomaterials is attractive due to the outstanding light coupling effect, the ease of fabrication, and integration with one-dimensional(1-D) semiconductor materials. The light absorption efficiency can be enhanced significantly, and the corresponding light-toelectricity conversion efficiency can be as high as their bulk counterparts. Also, the amount of active materials used can be reduced. This review summarizes the recent development of 1-D nanomaterials for photovoltaic applications, including the anti-reflection, the light absorption,the minority diffusion, and the semiconductor junction properties. With solid progress and prospect shown in the past 10 years, 1-D semiconductor nanomaterials are attractive and promising for the realization of high-efficiency and low-cost solar cells.Ning Han Zaixing Yang Lifan Shen Hao Lin Ying Wang Edwin Y.B.Pun Yunfa Chen Johnny C.Ho 2016Science Bulletin2016,61,5:3
14Determination of time-and size-dependent fine particle emission with varied oil heating in an experimental kitchen显示文摘Particulate matter(PM) from cooking has caused seriously indoor air pollutant and aroused risk to human health.It is urged to get deep knowledge of their spatial-temporal distribution of source emission characteristics,especially ultrafine particles(UFP < 100 nm) and accumulation mode particles(AMP 100-555 nm).Four commercial cooking oils are auto dipped water to simulate cooking fume under heating to 255℃ to investigate PM emission and decay features between 0.03 and 10 μm size dimension by electrical low pressure impactor(ELPI) without ventilation.Rapeseed and sunflower produced high PM_(2.5) around5.1 mg/m^3,in comparison with those of soybean and corn(5.87 and 4.55 mg/m^3,respectively)at peak emission time between 340 and 450 sec since heating oil,but with the same level of particle numbers 6-9 × 10~5/cm^3.Mean values of PM_(1.0)/PM_(2.5) and PM_(2.5)/PM_(10) at peak emission time are around 0.51-0.55 and 0.23-0.29.After 15 min naturally deposition,decay rates of PM_(1.0),PM_(2.5) and PM_(10) are 13.3%-29.8%,20.1%-33.9%and 41.2%-54.7%,which manifest that PM_(1.0) is quite hard to decay than larger particles,PM_(2.5) and PM_(1.0).The majority of the particle emission locates at 43 nm with the largest decay rate at 75%,and shifts to a larger size between137 and 555 nm after 15 min decay.The decay rates of the particles are sensitive to the oil type.Shuangde Li Jiajia Gao Yiqing He Liuxu Cao Ang Li Shengpeng Mo Yunfa Chen Yaqun Cao 2017Journal of Environmental Sciences2017,29,1:3
15Promotion of transition metal oxides on the NH3-SCR performance of ZrO2-CeO2 catalyst显示文摘Weiman Li 2017Frontiers of Environmental Science & Engineering2017,11,2:2
16Preparation and characterization of a novel hybrid chelating material for effective adsorption of Cu(Ⅱ)and Pb(Ⅱ)显示文摘The discharge of heavy metal ions such as Cu^2+and Pb^2+poses a severe threat to public health and the environment owing to their extreme toxicity and bioaccumulation through food chains Herein, we report a novel organic–inorganic hybrid adsorbent, Al(OH)_3-poly(acrylamide dimethyldiallylammonium chloride)-graft-dithiocarbamate(APD), for rapid and effectiv removal of Cu^2+and Pb^2+. In this adsorbent, the 'star-like' structure of Al(OH)3 poly(acrylamide-dimethyldiallylammonium chloride) served as the support of dithiocarbamat(DTC) functional groups for easy access of heavy metal ions and assisted development of larg and compact floccules. The synthesized adsorbent was characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), Fourier transform infrared spectroscopy(FTIR), and thermogravimetric analysis(TGA). APD was demonstrated to hav rapid adsorption kinetics with an initial rate of 267.379 and 2569.373 mg/(g·min) as well a superior adsorption capacities of 317.777 and 586.699 mg/g for Cu^2+and Pb^2+respectively. Th adsorption process was spontaneous and endothermic, involving intraparticle diffusion and chemical interaction between heavy metal ions and the functional groups of APD. To assess it versatility and wide applicability, APD was also used in turbid heavy metal wastewater, and performed well in removing suspended particles and heavy metal ions simultaneously through flocculation and chelation. The rapid, convenient and effective adsorption of Cu^2+and Pb^2+give APD great potential for heavy metal decontamination in industrial applications.Ya Liu Peng Qian Yang Yu Bo Yu Yongliang Wang Shufeng Ye Yunfa Chen 2018Journal of Environmental Sciences2018,30,5:2
17TAILORING OF PORE SIZE IN MESOPOROUS SILICA WITH STEARIC ACID AND PVP显示文摘Mesoporous silica was prepared using tetrathoxysilane (TEOS), cetadecyltrimethylammonium bromide (CTAB), aqueous ammonia, acetone and water as silica source, template agent, precipitator and solvent respectively.Stearic acid and polyvinylpyrrolidone (PVP) were employed as additional templates to tailor the pore size in the resultant porous silica. BET, SAXRD and SEM analyses were used to characterize the surface area, pore size, pore structure,pore regularity and morphology of the sample. BET measurement results showed that PVP could increase the surface area but diminish the pore size while stearic acid could decrease the surface area but enlarge the pore size. SAXRD analysis indicated that more additional template introduction gave rise to less order-structured products. All these various results could be attributed to the differently modified CTAB micelles involving stearic acid and PVP addition.Haidi Liu Shufeng Ye Yunfa Chen 2005China Particuology2005,3,6:2
18Filter paper-templated preparation of ZnO thin films and examination of their gas-sensing properties显示文摘ZnO thin films prepared by using quantitative filter paper as a template and Zn(CH3CO2) 2·2H2O ethanol precursor solution were characterized by scanning electron microscopy(SEM) and X-ray diffraction(XRD) . The effects of sample calcination temperature,precursor concentration and filter paper types were studied,and the growth process was investigated by infra-red(IR) spectroscopy and thermogravimetric analysis/differential thermal analysis(TGA/DTA) . The results show that samples soaked in a 1.5 mol/L Zn(CH3CO2) 2·2H2O ethanol solution and calcined at 600 °C yield ZnO films of uniform particle size,approx-imately 30,40 and 50 nm,for fast-,medium-and slow-speed filter papers,respectively. The formaldehyde gas sensing properties of the ZnO nanoparticles were tested,showing that the material prepared from fast-speed filter paper has a higher response to 120-205 ppm formaldehyde at 400 °C than that prepared from medium-or slow-speed paper,which depends on the particle size.Bao Wang Ning Han Dong Meng Renliang Yue Jinghui Yan Yunfa Chen 2011Particuology2011,9,3:2
19Effects of acidic amino acids on hydroxyapatite morphology 显示文摘GAO Weimin RUAN Chengxiang CHEN Yunfa 2007Key Eng Mater2007,336,3:1
20The Effect of the Reaction on the Morphology of Coating Layers of Alumina Hydrate on Silicon Arbide Whiskers 显示文摘Hiroyuki Nakamura Chen Yunfa Kunio Kimura 2001Power Technology2001,117,:1
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