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Evaluating the Effects of Graviton Redshift upon Spiral Galaxy Rotation Curves, Surface Brightness Magnitudes and Gravitational Lensing
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作者 Firmin J. Oliveira 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第3期967-985,共19页
The effects of the gravitational redshift of gravitons upon spiral galaxy rotation energy are compared to the standard mass to light analyses in obtaining rotation curves. The derivation of the total baryonic matter c... The effects of the gravitational redshift of gravitons upon spiral galaxy rotation energy are compared to the standard mass to light analyses in obtaining rotation curves. The derivation of the total baryonic matter compares well with the standard theory and the rotation velocity is matched to a high precision. The stellar mass distributions obtained from the fit with graviton energy loss are used to derive the surface brightness magnitudes for the galaxies, which agree well with the observed measurements. In a new field of investigation, the graviton theory is applied to the observations of gravitational lenses. The results of these applications of the theory suggest that it can augment the standard methods and may eliminate the need for dark matter. 展开更多
关键词 GRAVITONS Gravitational Redshift surface brightness Gravitational Lens Lens Mass
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Theoretical characterization of the adsorption configuration of pyrrole on Si(100)surface by x-ray spectroscopy
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作者 李好情 明静 +3 位作者 姜志昂 李海波 马勇 宋秀能 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期430-435,共6页
The possible configurations of pyrrole absorbed on a Si(100)surface have been investigated by x-ray photoelectron spectroscopy(XPS)and near-edge x-ray absorption fine structure(NEXAFS)spectra.The C-1s XPS and NEXAFS s... The possible configurations of pyrrole absorbed on a Si(100)surface have been investigated by x-ray photoelectron spectroscopy(XPS)and near-edge x-ray absorption fine structure(NEXAFS)spectra.The C-1s XPS and NEXAFS spectra of these adsorption configurations have been calculated by using the density functional theory(DFT)method and fullcore hole(FCH)approximation to investigate the relationship between the adsorption configurations and the spectra.The result shows that the XPS and NEXAFS spectra are structurally dependent on the configurations of pyrrole absorbed on the Si(100)surface.Compared with the XPS,the NEXAFS spectra are relatively sensitive to the adsorption configurations and can accurately identify them.The NEXAFS decomposition spectra produced by non-equivalent carbon atoms have also been calculated and show that the spectral features vary with the diverse types of carbon atoms and their structural environments. 展开更多
关键词 PYRROLE silicon surface x-ray photoelectron spectroscopy(XPS) near-edge x-ray absorption fine structure(NEXAFS)
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Surface Brightness Temperature Variation of Different Land Use Types
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作者 石亦霏 查勇 《Agricultural Science & Technology》 CAS 2011年第12期1873-1876,1971,共5页
[Objective] The aim of this study is to investigate the surface brightness temperature variation of different land use types.[Method] Based on MODIS data in 2008 and IGBP land classification system,the surface brightn... [Objective] The aim of this study is to investigate the surface brightness temperature variation of different land use types.[Method] Based on MODIS data in 2008 and IGBP land classification system,the surface brightness temperature in the Yangtze River Delta area was calculated,and its rules and reasons were also discussed in this study.[Result] Different land use types had its own special brightness temperature variation.During the day,the brightness temperature was as follows:grassland or urban and built-up landcropland,forest land and barrenwetland and water.During the night,the brightness temperature was as follows:water,wetland and barrengrassland or urban and built-up landforest land and cropland.Brightness temperature showed the trend of high in summer and low in winter or increasing in spring and decreasing in fall.The characteristics of surface thermal radiation could be reflected better by brightness temperature at night.Solar radiation,mixed pixel,heat capacity,water content were the main reasons for the difference of brightness temperature in different land types.[Conclusion] The brightness temperature variation of different land use types has significance for water content analysis in soil and dynamic monitoring of land use. 展开更多
关键词 MODIS Remote sensing surface brightness temperature Land use type
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Utilizing a new soil effective temperature scheme and archived satellite microwave brightness temperature data to estimate surface soil moisture in the Nagqu region, Tibetan Plateau of China 被引量:1
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作者 TIAN Hui Mudassar IQBAL 《Journal of Arid Land》 SCIE CSCD 2018年第1期84-100,共17页
Since the early 2000s, many satellite passive microwave brightness temperature (BT) archives, such as the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) BTs, have become the useful ... Since the early 2000s, many satellite passive microwave brightness temperature (BT) archives, such as the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) BTs, have become the useful resources for assessing the changes in the surface and deep soil moistures over both arid and semi-arid regions. In this study, we used a new soil effective temperature (T scheme and the archived AMSR-E BTs to estimate surface soil moisture (SM) over the Nagqu region in the central Tibetan Plateau, China. The surface and deep soil temperatures required for the calculation of regional-scale T were obtained from outputs of the Community Land Model version 4.5 (CLM4.5). In situ SM measurements at the CEOP-CAMP/Tibet (Coordinated Enhanced Observing Period Asia-Australia Monsoon Project on the Tibetan Plateau) experimental sites were used to validate the AMSR-E-based SM estimations at regional and single-site scales. Furthermore, the spatial distribution of monthly mean surface SM over the Nagqu region was obtained from 16 daytime AMSR-E BT observations in July 2004 over the Nagqu region. Results revealed that the AMSR-E-based surface SM estimations agreed well with the in situ-based surface SM measurements, with the root mean square error (RMSE) ranging from 0.042 to 0.066 m3/m3 and the coefficient of determination (R2) ranging from 0.71 to 0.92 during the nighttime and daytime. The regional surface soil water state map showed a clear spatial pattern related to the terrain. It indicated that the lower surface SM values occurred in the mountainous areas of the northern, mid-western and southeastern parts of Nagqu region, while the higher surface SM values appeared in the low elevation areas such as the Tongtian River Basin, Namco Lake and bog meadows in the central part of Nagqu region. Our analysis also showed that the new T^scheme does not require special fitting parameters or additional assumptions, which simplifies the data requirements for regional-scale applications. This scheme combined with the archived satellite passive microwave BT observations can be used to estimate the historical surface SM for hydrological process studies over the Tibetan Plateau regions. 展开更多
关键词 soil effective temperature archived AMSR-E brightness temperature CLM4.5 soil temperature output Cumulative Distribution Function (CDF) matching surface soil moisture Tibetan Plateau
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Adaptive enhancement design of triply periodic minimal surface lattice structure based on non-uniform stress distribution
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作者 Yijin ZHANG Bin LIU +5 位作者 Fei PENG Heran JIA Zeang ZHAO Shengyu DUAN Panding WANG Hongshuai LEI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2023年第8期1317-1330,共14页
The Schwarz primitive triply periodic minimal surface(P-type TPMS)lattice structures are widely used.However,these lattice structures have weak load-bearing capacity compared with other cellular structures.In this pap... The Schwarz primitive triply periodic minimal surface(P-type TPMS)lattice structures are widely used.However,these lattice structures have weak load-bearing capacity compared with other cellular structures.In this paper,an adaptive enhancement design method based on the non-uniform stress distribution in structures with uniform thickness is proposed to design the P-type TPMS lattice structures with higher mechanical properties.Two types of structures are designed by adjusting the adaptive thickness distribution in the TPMS.One keeps the same relative density,and the other keeps the same of non-enhanced region thickness.Compared with the uniform lattice structure,the elastic modulus for the structure with the same relative density increases by more than 17%,and the yield strength increases by more than 10.2%.Three kinds of TPMS lattice structures are fabricated by laser powder bed fusion(L-PBF)with 316L stainless steel to verify the proposed enhanced design.The manufacture-induced geometric deviation between the as-design and as-printed models is measured by micro X-ray computed tomography(μ-CT)scans.The quasi-static compression experimental results of P-type TPMS lattice structures show that the reinforced structures have stronger elastic moduli,ultimate strengths,and energy absorption capabilities than the homogeneous P-TPMS lattice structure. 展开更多
关键词 additive manufacturing(AM) triply periodic minimal surface(TPMS) enhanced design model mechanical property micro x-ray computed tomography(u-CT)
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Three New Compounds Derived from Nitrofurantoin: X-Ray Structures and Hirshfeld Surface Analyses
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作者 Hao Wang Hongping Xiao +2 位作者 Na Liu Bo Zhang Qian Shi 《Open Journal of Inorganic Chemistry》 2015年第3期63-73,共11页
The polymorphism of nitrofurantoin (NF), 1), the cocrystals of NF:2,2’-bipyridyl = 2:1, 2) and NF: 1,10-phenanthroline = 1:1, 3) have been prepared and characterized. The crystal structure analyses show that there ar... The polymorphism of nitrofurantoin (NF), 1), the cocrystals of NF:2,2’-bipyridyl = 2:1, 2) and NF: 1,10-phenanthroline = 1:1, 3) have been prepared and characterized. The crystal structure analyses show that there are various weak forces among the molecules, such as C/N-H···O, N-H···N hydrogen bond interactions and π···π/lone pair stacking interactions, which play a key role in the assembly of supramolecular networks. A thorough analysis of Hirshfeld surfaces and fingerprint plots facilitates a comparison of intermolecular interactions in 1 - 3, which are crucial in building supramolecular architectures. 展开更多
关键词 NITROFURANTOIN CO-CRYSTALS INTERMOLECULAR INTERACTIONS x-ray Structures Hirshfeld surface
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AFM and XPS Study on the Surface and Interface States of CuPc and SiO_2 Films
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作者 陈金伙 王永顺 +2 位作者 朱海华 胡加兴 张福甲 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2006年第8期1360-1366,共7页
A CuPc/SiO2 sample is fabricated. Its morphology is characterized by atomic force microscopy, and the electron states are investigated by X-ray photoelectron spectroscopy. In order to investigate these spectra in deta... A CuPc/SiO2 sample is fabricated. Its morphology is characterized by atomic force microscopy, and the electron states are investigated by X-ray photoelectron spectroscopy. In order to investigate these spectra in detail, all of these spectra are normalized to the height of the most intense peak,and each component is fitted with a single Gaussian function. Analysis shows that the O element has great bearing on the electron states and that SiO2 layers produced by spurting technology are better than those produced by oxidation technology. 展开更多
关键词 CuPc/SiO2 x-ray photoelectron spectroscopy surface and interface analysis
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XPS study of surface absorbed oxygen of ABO_3 mixed oxides 被引量:9
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作者 赵馨 杨秋华 崔津津 《Journal of Rare Earths》 SCIE EI CAS CSCD 2008年第4期511-514,共4页
Perovskite-type complex oxides ABO3 (A=Sr, La; B=Mn, Fe, Co) were prepared by citric acid method. The degradation of water-solubilized dyes was carried out using the mixed oxides as photocatalyst. The surface absorb... Perovskite-type complex oxides ABO3 (A=Sr, La; B=Mn, Fe, Co) were prepared by citric acid method. The degradation of water-solubilized dyes was carried out using the mixed oxides as photocatalyst. The surface absorbed oxygen was analyzed using X-ray photoelectron spectroscopy (XPS). The results indicated that there was a relationship between the photocatalytic activity and the content of the surface absorbed oxygen. The higher the content of the surface absorbed oxygen was, the better the performance of the photocatalyst. 展开更多
关键词 PEROVSKITE x-ray photoelectron spectroscopy surface absorbed oxygen PHOTOCATALYSIS rare earths
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Surface texture evaluation of additively manufactured metallic cellular scaffolds for acetabular implants using X.ray computed tomography 被引量:2
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作者 Shan Lou Luca Pagani +3 位作者 Wenhan Zeng Muhammad U.Ghori Xiangqian Jiang Paul J.Scott 《Bio-Design and Manufacturing》 SCIE CSCD 2019年第2期55-64,共10页
The surface topography of acetabular implants plays a key role in providing cell attachment and proliferation.The measurement and characterisation of the surface texture of the cellular scaffold layer on the acetabula... The surface topography of acetabular implants plays a key role in providing cell attachment and proliferation.The measurement and characterisation of the surface texture of the cellular scaffold layer on the acetabular cup are very difficult due to the 3D nature of scaffold geometry.It is proposed to use X-ray computed tomography(XCT)to measure the surface texture of an electron beam melting-produced titanium acetabular cup.The surface texture of its cellular scaffold is evaluated using the newly developed 3D surface texture parameters,which allows surface characterisation on 3D triangular mesh surfaces.Four commonly used height parameters,i.e.the arithmetical mean height Sa,the root mean square height Sq,the skewness Ssk and the kurtosis Sku,are calculated from surface patches extracted from the XCT scanned triangular mesh surface.In addition,the surface peak density and pit density,which are more related to cell communication and proliferation,are estimated based on the 3D watershed segmentation.The Wolf pruning with an empirical threshold 12μm is used to control the over-segmentation. 展开更多
关键词 ADDITIVE manufacturing CELLULAR SCAFFOLD surface texture x-ray COMPUTED tomography
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Surface State of Carbon Fibers Modified by Electrochemical Oxidation 被引量:2
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作者 YunxiaGUO JieLIU JieyingLIANG 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2005年第3期371-375,共5页
Surface of polyacrylonitrile (PAN)-based carbon fibers was modified by electrochemical oxidation. The modification effect on carbon fibers surface was explored using atomic force microscopy (AFM), X-ray photoelectron ... Surface of polyacrylonitrile (PAN)-based carbon fibers was modified by electrochemical oxidation. The modification effect on carbon fibers surface was explored using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Results showed that on the modified surface of carbon fibers, the carbon contents decreased by 9.7% and the oxygen and nitrogen contents increased by 53.8% and 7.5 times, respectively. The surface roughness and the hydroxyl and carbonyl contents also increased. The surface orientation index was reduced by 1.5% which decreased tensile strength of carbon fibers by 8.1%, and the microcrystalline dimension also decreased which increased the active sites of carbon fiber surface by 78%. The physical and chemical properties of carbon fibers surface were modified through the electrochemical oxidative method, which improved the cohesiveness between the fibers and resin matrix and increased the interlaminar shear strength (ILSS) of carbon fibers reinforced epoxy composite (CFRP) over 20%. 展开更多
关键词 Polyacrylonitrile (PAN) Carbon fiber Electrochemical oxidation surface Atomic force microscopy (APM) x-ray photoelectron spectroscopy (XPS) x-ray diffraction (XRD)
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Mineralogical study of surface sediments in the western Arctic Ocean and their implications for material sources 被引量:2
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作者 DONG Linsen SHI Xuefa +5 位作者 LIU Yanguang FANG Xisheng CHEN Zhihua WANG Chunjuan ZOU Jianjun HUANG Yuanhui 《Advances in Polar Science》 2014年第3期192-203,共12页
Mineralogical analysis was performed on bulk sediments of 79 surface samples using X-ray diffraction. The analytical results, combined with data on ocean currents and the regional geological background, were used to i... Mineralogical analysis was performed on bulk sediments of 79 surface samples using X-ray diffraction. The analytical results, combined with data on ocean currents and the regional geological background, were used to investigate the mineral sources. Mineral assemblages in sediments and their distribution in the study area indicate that the material sources are complex. (1) Feldspar is abundant in the sediments of the middle Chukchi Sea near the Bering Strait, originating from sediments in the Anadyr River carried by the Anadyr Current. Sediments deposited on the western side of the Chukchi Sea are rich in feldspar. Compared with other areas, sediments in this region are rich in hornblende transported from volcanic and sedimentary rocks in Siberia by the Anadyr Stream and the Siberian Coastal Current. Sediments in the eastern Chukchi Sea are rich in quartz sourced from sediments of the Yukon and Kuskokwim rivers carried by the Alaska Coastal Current. Sediments in the northern Chukchi Sea are rich in quartz and carbonates from the Mackenzie River sediments. (2) Sediments of the southern and central Canada Basin contain little calcite and dolomite, mainly due to the small impact of the Beaufort Gyre carrying carbonates from the Canadian Arctic Islands. Compared with other areas, the mica content in the region is high, implying that the Laptev Sea is the main sediment source for the southern and central Canada Basin. In the other deep sea areas, calcite and dolomite levels are high caused by the input of large amounts of sediment carried by the Beaufort Gyre from the Canadian Arctic Islands (Banks and Victoria). The Siberian Laptev Sea also provides small amounts of sediment for this region. Furthermore, the Atlantic mid-water contributes some fine-grained material to the entire deep western Arctic Ocean. 展开更多
关键词 x-ray diffraction western Arctic Ocean MINERALS surface sediments SOURCES
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PREPARATION AND SURFACE PROPERTIES OF ACRYLIC COPOLYMERS CONTAINING FLUORINATED MONOMERS 被引量:1
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作者 Tai-jiang Gui Hao Wei +3 位作者 Ying Zhao Xiu-lin Wang Du-jin Wang Duan-fu Xu 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2006年第6期575-578,共4页
A series of copolymers comprising butylmethacrylate, styrene, butylacrylate, hydroxypropyl acrylate and perfluoroalkyl methacrylate were synthesized by the free radical polymerization using BPO as an initiator. The su... A series of copolymers comprising butylmethacrylate, styrene, butylacrylate, hydroxypropyl acrylate and perfluoroalkyl methacrylate were synthesized by the free radical polymerization using BPO as an initiator. The surface property of the copolymer films was subsequently characterized. The contact angle measurements and energy dispersive analysis of X-ray (EDAX) show that the length and content of perfluoroalkyl side chains in the copolymers are crucial for the preparation of the film with low surface energy. At a given content of fluorinated monomers in the copolymers, the longer the perfluoroalkyl side chain, the larger the water contact angle of the copolymer films will be. On the other hand, the higher the content of fluorinated monomers, the lower the surface energy is. The water contact angle increases with the increase of the fluorinated monomer content and reaches a plateau at 3 wt% of fluorinated monomer content. 展开更多
关键词 Acrylate copolymers Fluorinated monomers surface property Contact angle x-ray energy dispersive analysis.
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Zr(Ⅳ) surface sites determine CH3OH formation rate on Cu/ZrO2/SiO2-CO2 hydrogenation catalysts 被引量:2
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作者 Erwin Lam Kim Larmier +3 位作者 Shohei Tada Patrick Wolf Olga V. Safonova Christophe Copéret 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第11期1741-1748,共8页
Cu/ZrO2/SiO2 are efficient catalysts for the selective hydrogenation of CO2 to CH3OH. In order to understand the role of ZrO2 in these mixed-oxides based catalysts, in situ X-ray absorption spectroscopy has been carri... Cu/ZrO2/SiO2 are efficient catalysts for the selective hydrogenation of CO2 to CH3OH. In order to understand the role of ZrO2 in these mixed-oxides based catalysts, in situ X-ray absorption spectroscopy has been carried out on the Cu and Zr K-edge. Under reaction conditions, Cu remains metallic, while Zr is present in three types of coordination environment associated with 1) bulk ZrO2, 2) coordinatively saturated and 3) unsaturated Zr(Ⅳ) surface sites. The amount of coordinatively unsaturated Zr surface sites can be quantified by linear combination fit of reference X-Ray absorption near edge structure (XANES) spectra and its amount correlates with CH3OH formation rates, thus indicating the importance of Zr(Ⅳ) Lewis acid surface sites in driving the selectivity toward CH3OH. This finding is consistent with the proposed mechanism, where CO2 is hydrogenated at the interface between the Cu nanoparticles that split H2 and Zr(Ⅳ) surface sites that stabilizes reaction intermediates. 展开更多
关键词 CO2 hydrogenation ZrO2/SiO2 supported Cu nanoparticles Lewis acidic surface sites In situ x-ray absorption spectroscopy
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Properties of Surface Film on X70 Pipeline Steel in CO_3^(2-)-/HCO_3^- Environment 被引量:1
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作者 胡钢 许淳淳 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2005年第2期254-258,共5页
The electrochemical behavior of X70 pipeline steel in (0.5mol·L-1 Na2CO3+1 mol·L-1 NaHCO3) solution was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). X-ray photoel... The electrochemical behavior of X70 pipeline steel in (0.5mol·L-1 Na2CO3+1 mol·L-1 NaHCO3) solution was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to analyze the composition and microstructure of the surface film. The results showed that there were two anodic peaks at -600 mV and -350 mV. The surface film formed at -600 mV mainly consisted of ferrous carbonates and ferrous hydroxycarbonates. It had a small reaction resistance. It was metastable and possessed poor protective property. Numerous pits and microcracks existed on the film, which could be the active paths for the initiation of stress corrosion cracking. The surface film formed at -350 mV, mainly consisted of ferric oxides. It has high reaction resistance and offered good protection for the substrate. 展开更多
关键词 X70 pipeline steel surface film electrochemical impedance spectroscopy x-ray photoelectron spectroscopy scanning electron microscopy
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Surface Modification of Fluororubber Using Atmospheric Pressure Dielectric Barrier Discharge(DBD) 被引量:1
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作者 童薇 卢灿辉 +1 位作者 蔡勇昆 黄奕刚 《Plasma Science and Technology》 SCIE EI CAS CSCD 2007年第3期296-300,共5页
Fluoride rubber F2311 film, an alternating copolymer of CF2-CFC1 (CTFE) and CH2-CF2 (VF2) components, was treated by atmospheric pressure dielectric barrier discharge (DBD) in air. The surface structure, topogra... Fluoride rubber F2311 film, an alternating copolymer of CF2-CFC1 (CTFE) and CH2-CF2 (VF2) components, was treated by atmospheric pressure dielectric barrier discharge (DBD) in air. The surface structure, topography and surface chemistry of the treated F2311 films were characterized by contact angle measurement, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS), respectively. The experimental results showed that a short time air plasma treatment led to morphological, wettability and chemical changes in the F2311 films. The surface hydrophilicity increased greatly after the plasma treatment, the static water contact angle decreased from 98.6° to 32°, and oxygen containing groups (C=O, O-C=O, etc. ) were introduced. Atomic force microscopy revealed that plasma produced by DBD etched F2311 films obviously. The roughness of the samples increased remarkably with the formation of peaks and valleys on the treated surfaces. The increased surface wettability may be correlated with both the introduction of hydrophilic groups due to air plasma oxidation of the surface and the change in surface morphology etched by DBD. 展开更多
关键词 fluororubber dielectric barrier discharge (DBD) surface modification contact angle atomic force microscopy (AFM) x-ray photoelectron spectroscopy (XPS)
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Novel Perchlorate and Sulphate Salts of 2-Aminonicotinic Acid:Synthesis,Characterization,Thermal Studies and Hirshfeld Surface Analysis 被引量:1
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作者 马玉恒 葛书旺 +1 位作者 沈亚 孙柏旺 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2016年第1期7-15,共9页
Since 2-aminonicotinic acid is a zwitterionic molecule,the salt or co-crystal strategy was used for the precipitation under identical conditions and obtained two novel salts: salt 1 with 2:1:2 stoichiometry of 2-am... Since 2-aminonicotinic acid is a zwitterionic molecule,the salt or co-crystal strategy was used for the precipitation under identical conditions and obtained two novel salts: salt 1 with 2:1:2 stoichiometry of 2-aminonicotinic acid:perchloric acid:H2O and salt 2 with 2:1:3 stoichiometry of 2-aminonicotinic acid:sulfuric acid:H2O. Their crystal structures were characterized by single-crystal X-ray diffraction,differential scanning calorimetry(DSC) and thermogravimetric analyses(TGA). The structure determination shows that two salts are both primarily stabilized by the strong N–H…O hydrogen bonding interaction between 2-aminonicotinic acid and its corresponding acids. Constituents of the salt-crystalline phase were also investigated in terms of Hirshfeld surfaces. In the crystal lattice,a three-dimensional hydrogen-bonded network is observed,including the formation of a two-dimensional molecular scaffolding motif. Hirshfeld surfaces and fingerprint plots of two salts show that the structures are stabilized by H…H,O–H…O and C–O…π intermolecular interactions. 展开更多
关键词 2-aminonicotinic acid salt x-ray diffraction Hirshfeld surfaces
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Surface photometry and radial color gradients of nearby luminous early-type galaxies in SDSS Stripe 82 被引量:1
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作者 Fang-Zhou Jiang Song Huang Qiu-Sheng Gu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2011年第3期309-326,共18页
We make use of the images from the Sloan Digital Sky Survey Stripe 82(Stripe 82) to present an analysis of r band surface brightness profiles and radial color gradients(g-r,u-r) in our sample of 111 nearby early-t... We make use of the images from the Sloan Digital Sky Survey Stripe 82(Stripe 82) to present an analysis of r band surface brightness profiles and radial color gradients(g-r,u-r) in our sample of 111 nearby early-type galaxies(ETGs) .Thanks to the Stripe 82 images,each of which is co-added from about 50 single frames,we are able to pay special attention to the low-surface-brightness areas(LSB areas) of the galaxies.The LSB areas affect the Sérsic fittings and concentration indices by making both of the indices less than the typical values for ETGs.In the Sérsic fits to all the surface brightness profiles,we found some Sérsic indices that range from 1.5 to 2.5,much smaller than those of typical de Vaucouleur profiles and relatively close to those of exponential disks,and some others much larger than four but still with accurate fitting.Two galaxies cannot be fitted with a single Sérsic profile,but once we try double Sérsic profiles,the fittings are improved:one with a profile relatively close to the de Vaucouleur law in the inner area and a profile relatively close to an exponential law in the LSB area,the other with a nice fitting in the inner area but still having a failed fitting in the outer area.About 60%of the sample has negative color gradients(red-core) within 1.5Re,much more than the approximately 10%positive ones(blue-core) within the same radius.However,taking into account the LSB areas,we find that the color gradients are not necessarily monotonic:about one third of the red-core(or blue-core) galaxies have positive(or negative) color gradients in the outer areas. So LSB areas not only make ETGs’Sérsic profiles deviate from de Vaucouleur ones and shift to the disk end,but also reveal that quite a number of ETGs have opposite color gradients in inner and outer areas.These outcomes remind us of the necessity of double-Sérsic fitting.These LSB phenomena may be interpreted by mergers and thus have different metallicity in the outer areas.Isophotal parameters are also discussed briefly in this paper with the following conclusion:there are more disky nearby ETGs that are identified than boxy ones. 展开更多
关键词 galaxies:early-type galaxies—galaxies:surface brightness profiles and color gradients—techniques:photometric
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Studying a kind of portable ultra-bright microfocus x-ray source
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作者 王凯歌 王雷 牛憨笨 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第5期1807-1813,共7页
This paper studies the properties of a kind of portable ultra-bright microfocus x-ray source with the Monte-Carlo method in detail. The new x-ray source consists of an electron-emission system, an electrostatic focusi... This paper studies the properties of a kind of portable ultra-bright microfocus x-ray source with the Monte-Carlo method in detail. The new x-ray source consists of an electron-emission system, an electrostatic focusing system and a metal target. A crystal Lanthanum Hexaboride cathode, a Wehnelt grid and an extracted electrode compose the triode electrode electron-gun system. Two equal radius cylinder electrodes form the focusing system. The key factors determining the focus properties of the electron beam such as the ratio Dw/H, grid bias Vg, and the properties of the extracted electrode arc numerically studied. The calculated results reveal that when Dw/H, Vg, the length of the extracted electrode, and the distance between the grid and the extracted electrode equals 5, q).6 kV, 10 mm, and 8 mm respectively, the electron beam focal spot can be concentrated down to 9 μm in radius and a reasonable focal length about 72.5 mm can be achieved, at the same time, the cathode emission currents can be as high as 30 mA. 展开更多
关键词 microfocus x-ray source high brightness micro-focal spot Monte-Carlo method
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Revealing the inhomogeneous surface chemistry on the spherical layered oxide polycrystalline cathode particles
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作者 Zhi-Sen Jiang Shao-Feng Li +6 位作者 Zheng-Rui Xu Dennis Nordlund Hendrik Ohldag Piero Pianetta Jun-Sik Lee Feng Lin Yi-Jin Liu 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第2期81-86,共6页
The hierarchical structure of the composite cathodes brings in significant chemical complexity related to the interfaces,such as cathode electrolyte interphase.These interfaces account for only a small fraction of the... The hierarchical structure of the composite cathodes brings in significant chemical complexity related to the interfaces,such as cathode electrolyte interphase.These interfaces account for only a small fraction of the volume and mass,they could,however,have profound impacts on the cell-level electrochemistry.As the investigation of these interfaces becomes a crucial topic in the battery research,there is a need to properly study the surface chemistry,particularly to eliminate the biased,incomplete characterization provided by techniques that assume the homogeneous surface chemistry.Herein,we utilize nano-resolution spatially-resolved x-ray spectroscopic tools to probe the heterogeneity of the surface chemistry on LiNi0.8Mn0.1Co0.1O2 layered cathode secondary particles.Informed by the nano-resolution mapping of the Ni valance state,which serves as a measurement of the local surface chemistry,we construct a conceptual model to elucidate the electrochemical consequence of the inhomogeneous local impedance over the particle surface.Going beyond the implication in battery science,our work highlights a balance between the high-resolution probing the local chemistry and the statistical representativeness,which is particularly vital in the study of the highly complex material systems. 展开更多
关键词 Ni-rich CATHODE x-ray NANOPROBE redox heterogeneity surface chemistry
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High-brightness photo-injector with standing-wave buncher-based ballistic bunching scheme for inverse Compton scattering light source
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作者 Jian-Xin Wang Kui Zhou +7 位作者 Peng Li De-Xin Xiao Li-Jun Shan Xu-Ming Shen Yu Liu Zheng Zhou Han-Bin Wang Dai Wu 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2022年第4期51-61,共11页
We report our recent progress in the design and simulation of a high-brightness S-band photo-injector with a ballistic bunching scheme aimed at driving an inverse Compton scattering(ICS)X-ray source.By adding a short ... We report our recent progress in the design and simulation of a high-brightness S-band photo-injector with a ballistic bunching scheme aimed at driving an inverse Compton scattering(ICS)X-ray source.By adding a short standing-wave buncher between the RF gun and first booster in a conventional S-band photo-injector,electron bunches with a 500 pC charge can be compressed to the sub-picosecond level with very limited input RF power and an unchanged basic layout of the photo-injector.Beam dynamics analysis indicates that fine tuning of the focusing strength of the gun and linac solenoid can well balance additional focusing provided by the standing wave buncher and generate a well-compensated transverse emittance.Thorough bunching dynamics simulations with different operating conditions of the buncher show that a buncher with more cells and a moderate gradient is suitable for simultaneously obtaining a short bunch duration and low emittance.In a typical case of a 9-cell buncher with a 38 MV/m gradient,an ultrashort bunch duration of 0.5 ps(corresponding to a compression ratio of>5)and a low emittance of<1 mm mrad can be readily obtained for a 500 pC electron pulse.This feasible ballistic bunching scheme will facilitate the implementation of an ultrashort pulse mode inverse Compton scattering X-ray source on most existing S-band photo-injectors. 展开更多
关键词 Beam brightness Ballistic bunching Emittance compensation Compton scattering x-ray source
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