The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial...The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial concentration was studied using the batch method. X-ray absorption spectroscopy （XAS） was used to examine the coordination environment of the Cu（ll） adsorbed by HA at a molecular level. Moreover, the chemical compositions of the isolated HA were characterized by elemental analysis and solid-state 13C nuclear magnetic resonance spectroscopy （NMR）. The kinetic data showed that the adsorption equilibrium can be achieved within 8 h. The adsorption kinetics followed the pseudo-second-order equation. The adsorption isotherms could be well fitted by the Langmuir model, and the maximum adsorption capacities of Cu（ll） on CHA, PHA, and LHA were 229.4,210.4, and 197.7 mg g-1, respectively. The adsorption of Cu（Ⅱ） on HA increased with the increase in pH from 2 to 7, and maintained a high level at pH〉7. The adsorption of Cu（Ⅱ） was also strongly influenced by the low ionic strength of 0.01 to 0.2 mol L-1 NaNO3, but was weakly influenced by high ionic strength of 0.4 to 1 mol L-1 NaNO3. The Cu（Ⅱ） adsorption on HA may be mainly attributed to ion exchange and surface complexation. XAS results revealed that the binding site and oxidation state of Cu adsorbed on HA surface did not change at the initial Cu（Ⅱ） concentrations of 15 to 40 mg L 1. For all the Cu（Ⅱ） adsorption samples, each Cu atom was surrounded by 40/N atoms at a bond distance of 1.95 A in the first coordination shell. The presence of the higher Cu coordination shells proved that Cu（Ⅱ） was adsorbed via an inner-sphere covalent bond onto the HA surface. Among the three HA samples, the adsorption capacity and affinity of CHA for Cu（Ⅱ） was the greatest, followed by that of PHA and LHA. All the three HA samples exhibited similar types of elemental and functional groups, but different conte展开更多
Fruiting bodies from the Agaricus genus have been found to contain non-toxic arsenobetaine（AB） as a major compound. It is unknown whether AB is formed during the vegetative or reproductive life stages of the fungus,...Fruiting bodies from the Agaricus genus have been found to contain non-toxic arsenobetaine（AB） as a major compound. It is unknown whether AB is formed during the vegetative or reproductive life stages of the fungus, or by the surrounding microbial community, but AB＇s structural similarity to glycine betaine has led to the hypothesis that AB may be adventitiously accumulated as an osmolyte. To investigate the potential formation of AB during the reproductive life stage of Agaricus species, growth substrate and fungi were collected during the commercial growth of Agaricus bisporus and analyzed for arsenic speciation using HPLC-ICP-MS. AB was found to be the major arsenic compound in the fungus at the earliest growth stage of fruiting（the primordium）. The growth substrate mainly contained arsenate（As（V））. The distribution of arsenic in an A. bisporus primordium grown on As（V） treated substrate, and in a mature Agaricus campestris fruiting body collected from arsenic contaminated mine tailings, was mapped using two dimensional XAS imaging. The primordium and stalk of the mature fruiting body were both found to be growing around pockets of substrate material containing higher As concentrations, and AB was found exclusively in the fungal tissues. In the mature A. campestris the highest proportion of AB was found in the cap, supporting the AB as an osmolyte hypothesis. The results have allowed us to pinpoint the fungus life stage at which AB formation takes place,namely reproduction, which provides a direction for further research.展开更多
The mutual effects of metal cations （Cu2＋, Pb2＋, Zn2＋, and Cd2＋） and p-nitrophenol （NP） on their adsorption desorption behavior onto wheat ash were studied. Results suggested that Cu2＋, Pb2＋, and Zn2＋ dimin...The mutual effects of metal cations （Cu2＋, Pb2＋, Zn2＋, and Cd2＋） and p-nitrophenol （NP） on their adsorption desorption behavior onto wheat ash were studied. Results suggested that Cu2＋, Pb2＋, and Zn2＋ diminished the adsorption and increased the desorption of NP remarkably, while Cd2＋ had no such effect. In contrast, NP diminished the adsorption of Cu2＋, Pb2＋, and Zn2＋ onto ash, however, this suppression effect depended on the initial concentrations of metal cations. NP had no effect on Cd〉 adsorption on ash. Fourier transform infrared （FT-IR） and X-ray absorption spectroscopic （XAS） studies suggested the following mechanisms responsible for the metal suppression effect on NP adsorption： （1） large hydrated Cu2＋, Pb2＋, and Zn〉 shells occupied the surface of ash and prevent nonspecific adsorption of NP onto ash surface; （2） Cu2＋, Pb2＋, and Zn2＋ may block the micropores of ash, resulting in decreased adsorption of NP; （3） cornplexation of Cu2＋, Pb2＋, and Zn2＋ was likely via carboxyl, hydroxylic and phenolic groups of wheat ash and these same groups may also react with NP during adsorption. As a ＂soft acid＂, Cd2＋ is less efficient in the complexation of oxygencontaining acid groups than Cu2＋, Pb2＋, and Zn2＋. Thus, Cd2＋ had no effect on the adsorption of NP on wheat ash.展开更多
Fractionations of rare earth elements (REEs) and their mechanisms in soybean were studied through application of exogenous mixed REEs under hydroponic conditions. Significant enrichment of middle REEs (MREEs) and heav...Fractionations of rare earth elements (REEs) and their mechanisms in soybean were studied through application of exogenous mixed REEs under hydroponic conditions. Significant enrichment of middle REEs (MREEs) and heavy REEs (HREEs) was observed in plant roots and leaves respectively, with slight fractionation between light REEs (LREEs) and HREEs in stems. Moreover, the tetrad effect was observed in these organs. Investigations into REE speciation in roots and in the xylem sap using X-ray absorption spectroscopy (XAS) and nanometer-sized TiO2 adsorption techniques, associated with other controlled experiments, demonstrated that REE fractionations should be dominated by fixation mechanism in roots caused by cell wall absorption and phosphate precipitation, and by the combined effects of fixation mechanism and transport mechanism in aboveground parts caused by solution complexation by intrinsic organic ligands. A conceptive model was established for REE fractionations in plants based on the above studies.展开更多
Bi_(1-x)Eu_(x)Fe_(0.95)Co_(0.05)O_(3 )(x=0.05,0.10,0.15,and 0.20) nanoparticles were prepared through the sol-gel technique.Its structure,local electronic structure,magnetic and electric properties were systematically...Bi_(1-x)Eu_(x)Fe_(0.95)Co_(0.05)O_(3 )(x=0.05,0.10,0.15,and 0.20) nanoparticles were prepared through the sol-gel technique.Its structure,local electronic structure,magnetic and electric properties were systematically investigated.X-ray diffraction data show(104),(110) bimodal alignment and high angular migration,indicating that with the increase of Eu substitution at Bi site,the structure of BFO undergoes a continuous change in crystal structure.The hysteresis loop and the FC/ZFC curve show how magnetism varies with the size of the field and temperature.Finally,the causes of magnetic changes were analyzed by studying SXAS and hysteresis loops.展开更多
In certain exceptional cases,capillary samples must be used to measure X-ray absorption spectra(XAS).However,the inho-mogeneous thickness of capillary samples causes XAS distortion.This study discusses the distortion ...In certain exceptional cases,capillary samples must be used to measure X-ray absorption spectra(XAS).However,the inho-mogeneous thickness of capillary samples causes XAS distortion.This study discusses the distortion and correction of the XAS curve caused by the inhomogeneous thickness of capillary samples.The relationship between the distorted XAS curveμ′d_(eq)(measured values)and the real absorption coefficientμ_(s)d_(eq)(true values)of the sample was established.The distortion was slight and negligible when the vertical size(2h)of the X-ray beam spot was smaller than 60%of the capillary tube’s inner diameter(2R_(in)).When h/R_(in)>1,X-ray leakage is inevitable and should be avoided during measurement.Partial X-ray leakage caused by an X-ray beam spot size larger than the inner diameter of the capillary tube leads to serious compressed distortion of the XAS curve.When h/R_(in)<1,the distorted XAS data were well corrected.Possible errors and their influence on the corrected XAS are also discussed.Simulations and corrections for distortions verify the feasibility and effectiveness of the corrected method.展开更多
Based on the high-energy-resolution fluorescence spectrometer on the BL14W1 beamline at Shanghai Synchrotron Radiation Facility,an in-situ high-energyresolution X-ray absorption spectroscopy technique,with an in-situ ...Based on the high-energy-resolution fluorescence spectrometer on the BL14W1 beamline at Shanghai Synchrotron Radiation Facility,an in-situ high-energyresolution X-ray absorption spectroscopy technique,with an in-situ heating cell,was developed.The high-energyresolution fluorescence detection for X-ray absorption near-edge spectroscopy(HERFD-XANES) was tested in a UO_2 oxidation experiment to measure the UL_3-edge,with higher signal-to-noise ratio and higher-energy-resolution than conventional XANES.The technique has potential application for in-situ study of uranium-based materials.展开更多
Externally applied magnetic fields have been used in this study to fabricate bamboo-like iron nanowires with or without a layer of Poly(methyl methacrylate) (PMMA). The hybrid PMMA/Fe nanowires were synthesized via ha...Externally applied magnetic fields have been used in this study to fabricate bamboo-like iron nanowires with or without a layer of Poly(methyl methacrylate) (PMMA). The hybrid PMMA/Fe nanowires were synthesized via hard X-ray synchrotron radiation polymerization with various treatment parameters. The results of XRD show that an oxide layer formed on the surface of the iron nanowires. The Fe2O3 and Fe3O4 phases coexist in the iron nanowires without X-ray irradiation. After X-ray irradiation, the Fe2O3 phase transformed into Fe3O4, which stabilized the iron nanowires. The results of XAS proved this phase transformation. TGA analysis confirmed the thermal properties and solid contents in these specimens. Their ferromagnetic behaviors were examined by magnetic hysteresis measurement, which indicated that the magnetic and structural properties of the nanowires can be manipulated by irradiation treatment. This may lead to a novel synthesis for iron nanowires that can be used in high thermal efficiency hyperthermia therapy.展开更多
目的:观察消癌舒(XAS)及其含药血清对Hela细胞增殖和迁移的影响,并初步探讨其作用机制。方法:采用倒置显微镜观察Hela细胞形态;四唑盐(MTT)法检测Hela细胞的增殖能力;Transwell观察Hela细胞的迁移能力;酶联免疫吸附实验(ELISA)检测Hela...目的:观察消癌舒(XAS)及其含药血清对Hela细胞增殖和迁移的影响,并初步探讨其作用机制。方法:采用倒置显微镜观察Hela细胞形态;四唑盐(MTT)法检测Hela细胞的增殖能力;Transwell观察Hela细胞的迁移能力;酶联免疫吸附实验(ELISA)检测Hela细胞糖类抗原125(CA125)的水平;real time RT-PCR法检测Hela细胞血管内皮生长因子(VEGF)mRNA的表达。结果:经消癌舒处理后Hela细胞形态发生了改变,表现为细胞折光度下降,体积明显缩小,形状变圆,消癌舒及其含药血清均明显抑制Hela细胞的增殖,消癌舒减少Hela细胞穿过滤膜的个数,降低Hela细胞CA125水平及VEGF mRNA的表达,且与顺铂联用效果更佳。结论:消癌舒及其含药血清明显抑制Hela细胞的增殖及迁移能力,与顺铂联用作用更明显,其机制可能与降低CA125水平和VEGF mRNA的表达有关。展开更多
A double-gate tunnel field-effect transistor （DG tunnel FET） has been designed and investigated for various channel materials such as silicon （Si）, gallium arsenide （GaAs）, alminium gallium arsenide （A1xGa1-xAs...A double-gate tunnel field-effect transistor （DG tunnel FET） has been designed and investigated for various channel materials such as silicon （Si）, gallium arsenide （GaAs）, alminium gallium arsenide （A1xGa1-xAs） and CNT using a nano ViDES Device and TCAD SILVACO ATLAS simulator. The proposed devices are com- pared on the basis of inverse subthreshold slope （SS）, ION/IoFF current ratio and leakage current. Using Si as the channel material limits the property to reduce leakage current with scaling of channel, whereas the A1xGa1-xAs based DG tunnel FET provides a better ION/IOFF current ratio （2.51 × 10^6） as compared to other devices keeping the leakage current within permissible limits. The performed silmulation of the CNT based channel in the double-gate tunnel field-effect transistor using the nano ViDES shows better performace for a sub-threshold slope of 29.4 mV/dec as the channel is scaled down. The proposed work shows the potential of the CNT channel based DG tunnel FET as a futuristic device for better switching and high retention time, which makes it suitable for memory based circuits.展开更多
ITIC is the milestone of non-fullerene small molecule acceptors used in organic solar cells. We study the electronic states and molecular orientation of ITIC film using photoelectron spectroscopy and x-ray absorption ...ITIC is the milestone of non-fullerene small molecule acceptors used in organic solar cells. We study the electronic states and molecular orientation of ITIC film using photoelectron spectroscopy and x-ray absorption spectroscopy. The negative integer charge transfer energy level is determined to be 4.00 ± 0.05 eV below the vacuum level, and the ionization potential is 5,75 ±0.10 eV. The molecules predominantly have the face-on orientation on inert substrates as long as the surfaces of the substrates are not too rough. These results provide the physical understanding of the high performance of ITIC-based solar ceils, which also afford implications to design more advanced photovoltaic small molecules.展开更多
The hydrated shell of both Fe2＋ and Fe3＋ aqueous solutions are investigated by using the molecular dynamics （MD） and X-ray absorption structure （XAS） methods. The MD simulations show that the first hydrated shel...The hydrated shell of both Fe2＋ and Fe3＋ aqueous solutions are investigated by using the molecular dynamics （MD） and X-ray absorption structure （XAS） methods. The MD simulations show that the first hydrated shells of both Fe2＋ and Fe3＋ are characterized by a regular octahedron with an Fe-O distance of 2.08 for Fe2＋ and 1.96 for Fe3＋, and rule out the occurrence of a Jahn-Teller distortion in the hydrated shell of an Fe2＋ aqueous solution. The corresponding X-ray absorption near edge fine structure （XANES） calculation successfully reproduces all features in the XANES spectra in Fe2＋ and Fe3＋ aqueous solution. A feature that is located at energy 1 eV higher than the white line （WL） in an Fe3＋ aqueous solution may be assigned to the contribution of the charge transfer.展开更多
Photo/electrocatalytic water splitting has been considered as one of the most promising approaches for the clean hydrogen production. Among various photo/electrocatalysts,2D nanomaterials exhibit great potential becau...Photo/electrocatalytic water splitting has been considered as one of the most promising approaches for the clean hydrogen production. Among various photo/electrocatalysts,2D nanomaterials exhibit great potential because of their conspicuous properties. Meanwhile,synchrotron-based soft X-ray absorption spectroscopy(XAS) as a powerful and element-specific technique has been widely used to explore the electronic structure of 2D photo/electrocatalysts to comprehensively understand their working mechanism for the development of high-performance catalysts. In this work, the recent developments of soft XAS techniques applied in 2D photo/electrocatalysts have been reviewed, mainly focusing on identifying the surface active sites,elucidating the location of heteroatoms, and unraveling the interfacial interaction in the composite.The challenges and outlook in this research field have also been emphasized. The present review provides an in-depth understanding on how soft XAS techniques unravel the correlations between structure and performance in 2D photo/electrocatalysts, which could guide the rational design of highly efficient catalysts for photo/electrocatalytic water splitting.展开更多
基金supported by the Key Technologies R&D Program of China (2013BAD07B02 and 2013BAC09B01)the Special Fund for Agro-Scientific Research in the Public Interest of China (201103003)+1 种基金the Postdoctoral Project of Jilin Province, China (01912)the Doctoral Initiative Foundation of Jilin Agricultural University, China (201216)
文摘The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial concentration was studied using the batch method. X-ray absorption spectroscopy （XAS） was used to examine the coordination environment of the Cu（ll） adsorbed by HA at a molecular level. Moreover, the chemical compositions of the isolated HA were characterized by elemental analysis and solid-state 13C nuclear magnetic resonance spectroscopy （NMR）. The kinetic data showed that the adsorption equilibrium can be achieved within 8 h. The adsorption kinetics followed the pseudo-second-order equation. The adsorption isotherms could be well fitted by the Langmuir model, and the maximum adsorption capacities of Cu（ll） on CHA, PHA, and LHA were 229.4,210.4, and 197.7 mg g-1, respectively. The adsorption of Cu（Ⅱ） on HA increased with the increase in pH from 2 to 7, and maintained a high level at pH〉7. The adsorption of Cu（Ⅱ） was also strongly influenced by the low ionic strength of 0.01 to 0.2 mol L-1 NaNO3, but was weakly influenced by high ionic strength of 0.4 to 1 mol L-1 NaNO3. The Cu（Ⅱ） adsorption on HA may be mainly attributed to ion exchange and surface complexation. XAS results revealed that the binding site and oxidation state of Cu adsorbed on HA surface did not change at the initial Cu（Ⅱ） concentrations of 15 to 40 mg L 1. For all the Cu（Ⅱ） adsorption samples, each Cu atom was surrounded by 40/N atoms at a bond distance of 1.95 A in the first coordination shell. The presence of the higher Cu coordination shells proved that Cu（Ⅱ） was adsorbed via an inner-sphere covalent bond onto the HA surface. Among the three HA samples, the adsorption capacity and affinity of CHA for Cu（Ⅱ） was the greatest, followed by that of PHA and LHA. All the three HA samples exhibited similar types of elemental and functional groups, but different conte
基金supported by the US Department of Energy-Basic Energy Sciencesthe Canadian Light Source and its funding partnerssupported by the U.S. DOE under Contract No.DE-AC02-06CH11357
文摘Fruiting bodies from the Agaricus genus have been found to contain non-toxic arsenobetaine（AB） as a major compound. It is unknown whether AB is formed during the vegetative or reproductive life stages of the fungus, or by the surrounding microbial community, but AB＇s structural similarity to glycine betaine has led to the hypothesis that AB may be adventitiously accumulated as an osmolyte. To investigate the potential formation of AB during the reproductive life stage of Agaricus species, growth substrate and fungi were collected during the commercial growth of Agaricus bisporus and analyzed for arsenic speciation using HPLC-ICP-MS. AB was found to be the major arsenic compound in the fungus at the earliest growth stage of fruiting（the primordium）. The growth substrate mainly contained arsenate（As（V））. The distribution of arsenic in an A. bisporus primordium grown on As（V） treated substrate, and in a mature Agaricus campestris fruiting body collected from arsenic contaminated mine tailings, was mapped using two dimensional XAS imaging. The primordium and stalk of the mature fruiting body were both found to be growing around pockets of substrate material containing higher As concentrations, and AB was found exclusively in the fungal tissues. In the mature A. campestris the highest proportion of AB was found in the cap, supporting the AB as an osmolyte hypothesis. The results have allowed us to pinpoint the fungus life stage at which AB formation takes place,namely reproduction, which provides a direction for further research.
基金supported by the National Natural Science Foundation of China (No.20707037,40603023)
文摘The mutual effects of metal cations （Cu2＋, Pb2＋, Zn2＋, and Cd2＋） and p-nitrophenol （NP） on their adsorption desorption behavior onto wheat ash were studied. Results suggested that Cu2＋, Pb2＋, and Zn2＋ diminished the adsorption and increased the desorption of NP remarkably, while Cd2＋ had no such effect. In contrast, NP diminished the adsorption of Cu2＋, Pb2＋, and Zn2＋ onto ash, however, this suppression effect depended on the initial concentrations of metal cations. NP had no effect on Cd〉 adsorption on ash. Fourier transform infrared （FT-IR） and X-ray absorption spectroscopic （XAS） studies suggested the following mechanisms responsible for the metal suppression effect on NP adsorption： （1） large hydrated Cu2＋, Pb2＋, and Zn〉 shells occupied the surface of ash and prevent nonspecific adsorption of NP onto ash surface; （2） Cu2＋, Pb2＋, and Zn2＋ may block the micropores of ash, resulting in decreased adsorption of NP; （3） cornplexation of Cu2＋, Pb2＋, and Zn2＋ was likely via carboxyl, hydroxylic and phenolic groups of wheat ash and these same groups may also react with NP during adsorption. As a ＂soft acid＂, Cd2＋ is less efficient in the complexation of oxygencontaining acid groups than Cu2＋, Pb2＋, and Zn2＋. Thus, Cd2＋ had no effect on the adsorption of NP on wheat ash.
基金the Key Project of the National Natural Science Foundation of China (Grant Nos. 40571146 and 20577053)
文摘Fractionations of rare earth elements (REEs) and their mechanisms in soybean were studied through application of exogenous mixed REEs under hydroponic conditions. Significant enrichment of middle REEs (MREEs) and heavy REEs (HREEs) was observed in plant roots and leaves respectively, with slight fractionation between light REEs (LREEs) and HREEs in stems. Moreover, the tetrad effect was observed in these organs. Investigations into REE speciation in roots and in the xylem sap using X-ray absorption spectroscopy (XAS) and nanometer-sized TiO2 adsorption techniques, associated with other controlled experiments, demonstrated that REE fractionations should be dominated by fixation mechanism in roots caused by cell wall absorption and phosphate precipitation, and by the combined effects of fixation mechanism and transport mechanism in aboveground parts caused by solution complexation by intrinsic organic ligands. A conceptive model was established for REE fractionations in plants based on the above studies.
基金Funded by the Research Project of Nanjing University of Posts and Telecommunications(Nos.NY217096 and NY213124)。
文摘Bi_(1-x)Eu_(x)Fe_(0.95)Co_(0.05)O_(3 )(x=0.05,0.10,0.15,and 0.20) nanoparticles were prepared through the sol-gel technique.Its structure,local electronic structure,magnetic and electric properties were systematically investigated.X-ray diffraction data show(104),(110) bimodal alignment and high angular migration,indicating that with the increase of Eu substitution at Bi site,the structure of BFO undergoes a continuous change in crystal structure.The hysteresis loop and the FC/ZFC curve show how magnetism varies with the size of the field and temperature.Finally,the causes of magnetic changes were analyzed by studying SXAS and hysteresis loops.
基金the National Key R&D Program of China(Nos.2022YFA1603802 and 2017YFA0403000)1W2B and 4B9A at the Beijing Synchrotron Radiation Facility.
文摘In certain exceptional cases,capillary samples must be used to measure X-ray absorption spectra(XAS).However,the inho-mogeneous thickness of capillary samples causes XAS distortion.This study discusses the distortion and correction of the XAS curve caused by the inhomogeneous thickness of capillary samples.The relationship between the distorted XAS curveμ′d_(eq)(measured values)and the real absorption coefficientμ_(s)d_(eq)(true values)of the sample was established.The distortion was slight and negligible when the vertical size(2h)of the X-ray beam spot was smaller than 60%of the capillary tube’s inner diameter(2R_(in)).When h/R_(in)>1,X-ray leakage is inevitable and should be avoided during measurement.Partial X-ray leakage caused by an X-ray beam spot size larger than the inner diameter of the capillary tube leads to serious compressed distortion of the XAS curve.When h/R_(in)<1,the distorted XAS data were well corrected.Possible errors and their influence on the corrected XAS are also discussed.Simulations and corrections for distortions verify the feasibility and effectiveness of the corrected method.
基金supported by the National Nature Science Foundation of China(Nos.11175244 and U1532259)
文摘Based on the high-energy-resolution fluorescence spectrometer on the BL14W1 beamline at Shanghai Synchrotron Radiation Facility,an in-situ high-energyresolution X-ray absorption spectroscopy technique,with an in-situ heating cell,was developed.The high-energyresolution fluorescence detection for X-ray absorption near-edge spectroscopy(HERFD-XANES) was tested in a UO_2 oxidation experiment to measure the UL_3-edge,with higher signal-to-noise ratio and higher-energy-resolution than conventional XANES.The technique has potential application for in-situ study of uranium-based materials.
文摘Externally applied magnetic fields have been used in this study to fabricate bamboo-like iron nanowires with or without a layer of Poly(methyl methacrylate) (PMMA). The hybrid PMMA/Fe nanowires were synthesized via hard X-ray synchrotron radiation polymerization with various treatment parameters. The results of XRD show that an oxide layer formed on the surface of the iron nanowires. The Fe2O3 and Fe3O4 phases coexist in the iron nanowires without X-ray irradiation. After X-ray irradiation, the Fe2O3 phase transformed into Fe3O4, which stabilized the iron nanowires. The results of XAS proved this phase transformation. TGA analysis confirmed the thermal properties and solid contents in these specimens. Their ferromagnetic behaviors were examined by magnetic hysteresis measurement, which indicated that the magnetic and structural properties of the nanowires can be manipulated by irradiation treatment. This may lead to a novel synthesis for iron nanowires that can be used in high thermal efficiency hyperthermia therapy.
文摘目的:观察消癌舒(XAS)及其含药血清对Hela细胞增殖和迁移的影响,并初步探讨其作用机制。方法:采用倒置显微镜观察Hela细胞形态;四唑盐(MTT)法检测Hela细胞的增殖能力;Transwell观察Hela细胞的迁移能力;酶联免疫吸附实验(ELISA)检测Hela细胞糖类抗原125(CA125)的水平;real time RT-PCR法检测Hela细胞血管内皮生长因子(VEGF)mRNA的表达。结果:经消癌舒处理后Hela细胞形态发生了改变,表现为细胞折光度下降,体积明显缩小,形状变圆,消癌舒及其含药血清均明显抑制Hela细胞的增殖,消癌舒减少Hela细胞穿过滤膜的个数,降低Hela细胞CA125水平及VEGF mRNA的表达,且与顺铂联用效果更佳。结论:消癌舒及其含药血清明显抑制Hela细胞的增殖及迁移能力,与顺铂联用作用更明显,其机制可能与降低CA125水平和VEGF mRNA的表达有关。
文摘A double-gate tunnel field-effect transistor （DG tunnel FET） has been designed and investigated for various channel materials such as silicon （Si）, gallium arsenide （GaAs）, alminium gallium arsenide （A1xGa1-xAs） and CNT using a nano ViDES Device and TCAD SILVACO ATLAS simulator. The proposed devices are com- pared on the basis of inverse subthreshold slope （SS）, ION/IoFF current ratio and leakage current. Using Si as the channel material limits the property to reduce leakage current with scaling of channel, whereas the A1xGa1-xAs based DG tunnel FET provides a better ION/IOFF current ratio （2.51 × 10^6） as compared to other devices keeping the leakage current within permissible limits. The performed silmulation of the CNT based channel in the double-gate tunnel field-effect transistor using the nano ViDES shows better performace for a sub-threshold slope of 29.4 mV/dec as the channel is scaled down. The proposed work shows the potential of the CNT channel based DG tunnel FET as a futuristic device for better switching and high retention time, which makes it suitable for memory based circuits.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11374258 and 11079028)
文摘ITIC is the milestone of non-fullerene small molecule acceptors used in organic solar cells. We study the electronic states and molecular orientation of ITIC film using photoelectron spectroscopy and x-ray absorption spectroscopy. The negative integer charge transfer energy level is determined to be 4.00 ± 0.05 eV below the vacuum level, and the ionization potential is 5,75 ±0.10 eV. The molecules predominantly have the face-on orientation on inert substrates as long as the surfaces of the substrates are not too rough. These results provide the physical understanding of the high performance of ITIC-based solar ceils, which also afford implications to design more advanced photovoltaic small molecules.
基金Supported by Knowledge Innovation Program of the Chinese Academy of Sciences (KJCX2-YW-N42)Key Important Project of National Natural Science Foundation of China (10734070)+1 种基金National Natural Science Foundation of China (NSFC 11079031, 10805055,10905067)National Basic Research Program of China (2009CB930804)
文摘The hydrated shell of both Fe2＋ and Fe3＋ aqueous solutions are investigated by using the molecular dynamics （MD） and X-ray absorption structure （XAS） methods. The MD simulations show that the first hydrated shells of both Fe2＋ and Fe3＋ are characterized by a regular octahedron with an Fe-O distance of 2.08 for Fe2＋ and 1.96 for Fe3＋, and rule out the occurrence of a Jahn-Teller distortion in the hydrated shell of an Fe2＋ aqueous solution. The corresponding X-ray absorption near edge fine structure （XANES） calculation successfully reproduces all features in the XANES spectra in Fe2＋ and Fe3＋ aqueous solution. A feature that is located at energy 1 eV higher than the white line （WL） in an Fe3＋ aqueous solution may be assigned to the contribution of the charge transfer.
基金financially supported by National Key R&D Program of China (2020YFA0406103)China Postdoctoral Science Foundation (2020T130754)National Natural Science Foundation of China (51902139, U1932211)。
文摘Photo/electrocatalytic water splitting has been considered as one of the most promising approaches for the clean hydrogen production. Among various photo/electrocatalysts,2D nanomaterials exhibit great potential because of their conspicuous properties. Meanwhile,synchrotron-based soft X-ray absorption spectroscopy(XAS) as a powerful and element-specific technique has been widely used to explore the electronic structure of 2D photo/electrocatalysts to comprehensively understand their working mechanism for the development of high-performance catalysts. In this work, the recent developments of soft XAS techniques applied in 2D photo/electrocatalysts have been reviewed, mainly focusing on identifying the surface active sites,elucidating the location of heteroatoms, and unraveling the interfacial interaction in the composite.The challenges and outlook in this research field have also been emphasized. The present review provides an in-depth understanding on how soft XAS techniques unravel the correlations between structure and performance in 2D photo/electrocatalysts, which could guide the rational design of highly efficient catalysts for photo/electrocatalytic water splitting.
