The authors studied the interaction of dioxouranium （VI） UO2^2＋ and thorium Th^4＋ ions with ATP （5＇-adenosine 5＇-triphosphate） and obtained a complex of adenosine with uranium UO2^2＋ and thorium Th^4＋ ions a...The authors studied the interaction of dioxouranium （VI） UO2^2＋ and thorium Th^4＋ ions with ATP （5＇-adenosine 5＇-triphosphate） and obtained a complex of adenosine with uranium UO2^2＋ and thorium Th^4＋ ions and used X-ray method to explore these complexes.展开更多
It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(...It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(A_(2)B_(2)O_(7)-type)catalysts with disordered defective cubic fluorite phased structure were successfully prepared by a colloidal crystal template method.3DOM structure promotes the accessibility of the gaseous reactants(O2and CH4)to the active sites.The co-doping of Ca and Sr ions in La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts improved the formation of oxygen vacancies,thereby leading to increased density of surface-active oxygen species(O_(2)^(-))for the activation of CH4and the formation of C2products(C2H6and C2H4).3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts exhibit high catalytic activity for OCM at low temperature.3DOM La1.7Sr0.3Ce1.7Ca0.3O7-δcatalyst with the highest density of O_(2)^(-)species exhibited the highest catalytic activity for low-temperature OCM,i.e.,its CH4conversion,selectivity and yield of C2products at 650℃are 32.2%,66.1%and 21.3%,respectively.The mechanism was proposed that the increase in surface oxygen vacancies induced by the co-doping of Ca and Sr ions boosts the key step of C-H bond breaking and C-C bond coupling in catalyzing low-temperature OCM.It is meaningful for the development of the low-temperature and high-efficient catalysts for OCM reaction in practical application.展开更多
Red-light-induced swelling of the protoplasts isolated from hypocotyl of etiolated mung bean (Phaseolus radiatus L.) was observed only when Ca2+ ions were present in the medium. The optimal CaCl2 concentration was 250...Red-light-induced swelling of the protoplasts isolated from hypocotyl of etiolated mung bean (Phaseolus radiatus L.) was observed only when Ca2+ ions were present in the medium. The optimal CaCl2 concentration was 250 μM. Swelling response declined when Ca2+ was supplied into the medium after red light irradiation. The Ca2+-chelator EGTA eliminated the red-light-induced swelling and 45Ca2+ accumulation in the protoplasts. In contrast, A23187, a Ca2+-ionophore, could mimic the effect of red light in darkness. These results indicate that Ca2+ may play a role in light signal transduction. In addition, swelling response was prevented by TFP and CPZ (both are CaM antagonists), implying the involvement of CaM in red-light-induced and Ca2+ -dependent protoplast swelling.展开更多
The interaction of MeV H2^+ molecular ions with thin layer graphene and graphite foils was studied by using a highresolution electrostatic analyzer.A large number of fragment protons were observed at zero degree(along...The interaction of MeV H2^+ molecular ions with thin layer graphene and graphite foils was studied by using a highresolution electrostatic analyzer.A large number of fragment protons were observed at zero degree(along the beam direction) when the H2^+ beam was passing through the monolayer graphene foil, which indicates that the electron of the H2^+ molecular ions can be stripped easily even by the monolayer graphene foil.More trailing than leading protons were found in the energy spectrum, which means significant wake effect was observed in the monolayer graphene foil.The ratio of the numbers of trailing protons over leading protons first increased with the thickness for the much thinner graphene foils, and then decreased with the thickness for the much thicker graphite foils, which indicates that the bending effect of the wake field on the trailing proton varied with the foil thickness.展开更多
Photoelectrocatalytic seawater splitting is a promising low-cost method to produce green hydrogen in a large scale.The effects of Cl^(-)ions in seawater on the performance of a photoanode have been reported in previou...Photoelectrocatalytic seawater splitting is a promising low-cost method to produce green hydrogen in a large scale.The effects of Cl^(-)ions in seawater on the performance of a photoanode have been reported in previous studies.However,few researches have been done on the roles of Cl^(-)ions in a photocathode.Herein,for the first time,we find that Cl^(-)ions in the electrolyte improve the photocurrent of a Si/In_(2)S_(3) photocathode by 50% at-0.6 V_(RHE).An in-situ X-ray photoelectron spectroscopy(XPS)characterization combined with the time-of-flight secondary-ion mass spectrometry by simulating photoelectrochemical conditions was used to investigate the interface charge transfer mechanism.The results suggest that there is an In_(2)^(+3)S_(3-x)(OH)_(2x)layer on the surface of In_(2)S_(3) in the phosphate buffer solution(PBS)electrolyte,which plays a role as an interface charge transfer mediator in the Si/In_(2)S_(3) photocathode.The In_(2)^(+3)S_(3-x)(OH)_(2x)surface layer becomes In_(2)^(+3)S_(3-x)(Cl)_(2x)in the PBS electrolyte with NaCl and accelerates the charge transfer rate at the In_(2)S_(3)/electrolyte interface.These results offer a new concept of regulating interface charge transfer mediator to enhance the performance of photoelectrocatalytic seawater splitting for hydrogen production.展开更多
A long wavelength emission fluorescent(612 nm)chemosensor with high selectivity for H_(2)PO_(4)^(−)ions was designed and synthesized according to the excited state intramolecular proton transfer(ESIPT).The sensor can ...A long wavelength emission fluorescent(612 nm)chemosensor with high selectivity for H_(2)PO_(4)^(−)ions was designed and synthesized according to the excited state intramolecular proton transfer(ESIPT).The sensor can exist in two tautomeric forms(‘keto’and‘enol’)in the presence of Fe^(3+)ion,Fe^(3+)may bind with the‘keto’form of the sensor.Furthermore,the in situ generated GY-Fe^(3+)ensemble could recover the quenched fluorescence upon the addition of H_(2)PO_(4)^(−)anion resulting in an off-on-type sensing with a detection limit of micromolar range in the same medium,and other anions,including F^(−),Cl^(−),Br^(−),I^(−),AcO^(−),HSO^(−)_(4),ClO^(−)_(4)and CN−had nearly no influence on the probing behavior.The test strips based on 2-[2-hydroxy-4-(diethylamino)phenyl]-1H-imidazo[4,5-b]phenazine and Fe^(3+)metal complex(GY-Fe^(3+))were fabricated,which could act as convenient and efficient H_(2)PO_(4)^(−)test kits.展开更多
The microhydration structure of nickel sulfate aqueous solution has been determined via density functional theory (DFT) calculation and extended X-ray absorption fine structure (EXAFS) spectroscopy.The geometric optim...The microhydration structure of nickel sulfate aqueous solution has been determined via density functional theory (DFT) calculation and extended X-ray absorption fine structure (EXAFS) spectroscopy.The geometric optimization and energy calculation of nickel sulfate hydrated clusters of the molecular formula [NiSO4(H2O)n ]^0 (n=1-12) were determined via DFT using the B3LYP method.Several possible initial structures were considered for clusters of each size to locate the equilibrium geometry.Based on the DFT calculation,the favorable structure of Ni^2+ includes the six-coordinated form of [NiSO4(H2O)n ]^0 clusters.The results of hydration energy calculation suggest that the six-coordinated contact ion pair (CIP) is the stable configuration for small hydration clusters (n≤5),while the solvent-shared ion pair (SSIP) represents the favorable structure for medium hydration clusters (6≤n≤10).The solvent is separated by x water molecules (xSIP,x≥2 is the number of water molecule between Ni^2+ and SO4^2-) in larger hydration clusters (n≥11).The EXAFS analysis of the NiSO 4 aqueous solutions and NiSO4 ·6H2O solid established that Ni^2+ was surrounded by six water molecules tightly forming an octahedral structure in the first hydration shell,and no CIP was found from 0.70 mol/L to 2.22 mol/L (near saturation).The Ni-O distance and coordinated number were 2.040±0.020 and 6.0±1.0,respectively.These results are consistent with the DFT calculations for [NiSO4(H2O)n ]^0 clusters.DFT and EXAFS are powerful techniques that can be used to enhance the resolution of NiSO 4 solution microstructure.展开更多
AF@MOF-808 incorporating the acriflavine(AF)dye into the nanocages of MOF-808 was constructed by one-pot hydrothermal method,whose crystallization,morphology and stability were characterized by the X-ray powder diffra...AF@MOF-808 incorporating the acriflavine(AF)dye into the nanocages of MOF-808 was constructed by one-pot hydrothermal method,whose crystallization,morphology and stability were characterized by the X-ray powder diffractometer(XRD),scanning electron microscope(SEM)and thermogravimetric analysis(TGA).AF@MOF-808 exhibits bright green light emission with the high quantum yield of 38.27%and can selectively detect Fe^(3+)ion and Cr_(2)O_(7)^(2-)anion from 12 kinds of metal ions or anions in the aqueous solution.展开更多
文摘The authors studied the interaction of dioxouranium （VI） UO2^2＋ and thorium Th^4＋ ions with ATP （5＇-adenosine 5＇-triphosphate） and obtained a complex of adenosine with uranium UO2^2＋ and thorium Th^4＋ ions and used X-ray method to explore these complexes.
基金supported by the National Key Research and Development Program of China(Nos.2022YFB3504100,2022YFB3506200)the National Natural Science Foundation of China(Nos.22208373,22376217)+1 种基金the Beijing Nova Program(No.20220484215)the Science Foundation of China University of Petroleum,Beijing(No.2462023YJRC030)。
文摘It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(A_(2)B_(2)O_(7)-type)catalysts with disordered defective cubic fluorite phased structure were successfully prepared by a colloidal crystal template method.3DOM structure promotes the accessibility of the gaseous reactants(O2and CH4)to the active sites.The co-doping of Ca and Sr ions in La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts improved the formation of oxygen vacancies,thereby leading to increased density of surface-active oxygen species(O_(2)^(-))for the activation of CH4and the formation of C2products(C2H6and C2H4).3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts exhibit high catalytic activity for OCM at low temperature.3DOM La1.7Sr0.3Ce1.7Ca0.3O7-δcatalyst with the highest density of O_(2)^(-)species exhibited the highest catalytic activity for low-temperature OCM,i.e.,its CH4conversion,selectivity and yield of C2products at 650℃are 32.2%,66.1%and 21.3%,respectively.The mechanism was proposed that the increase in surface oxygen vacancies induced by the co-doping of Ca and Sr ions boosts the key step of C-H bond breaking and C-C bond coupling in catalyzing low-temperature OCM.It is meaningful for the development of the low-temperature and high-efficient catalysts for OCM reaction in practical application.
文摘Red-light-induced swelling of the protoplasts isolated from hypocotyl of etiolated mung bean (Phaseolus radiatus L.) was observed only when Ca2+ ions were present in the medium. The optimal CaCl2 concentration was 250 μM. Swelling response declined when Ca2+ was supplied into the medium after red light irradiation. The Ca2+-chelator EGTA eliminated the red-light-induced swelling and 45Ca2+ accumulation in the protoplasts. In contrast, A23187, a Ca2+-ionophore, could mimic the effect of red light in darkness. These results indicate that Ca2+ may play a role in light signal transduction. In addition, swelling response was prevented by TFP and CPZ (both are CaM antagonists), implying the involvement of CaM in red-light-induced and Ca2+ -dependent protoplast swelling.
基金Project supported by the National Natural Science Foundation of China(Grant No.11575121)the National Magnetic Confinement Fusion Program of China(Grant No.2014GB125004)
文摘The interaction of MeV H2^+ molecular ions with thin layer graphene and graphite foils was studied by using a highresolution electrostatic analyzer.A large number of fragment protons were observed at zero degree(along the beam direction) when the H2^+ beam was passing through the monolayer graphene foil, which indicates that the electron of the H2^+ molecular ions can be stripped easily even by the monolayer graphene foil.More trailing than leading protons were found in the energy spectrum, which means significant wake effect was observed in the monolayer graphene foil.The ratio of the numbers of trailing protons over leading protons first increased with the thickness for the much thinner graphene foils, and then decreased with the thickness for the much thicker graphite foils, which indicates that the bending effect of the wake field on the trailing proton varied with the foil thickness.
基金supported by the National Natural Science Foundation of China(22279052)the China Postdoctoral Science Foundation(2023M741613)。
文摘Photoelectrocatalytic seawater splitting is a promising low-cost method to produce green hydrogen in a large scale.The effects of Cl^(-)ions in seawater on the performance of a photoanode have been reported in previous studies.However,few researches have been done on the roles of Cl^(-)ions in a photocathode.Herein,for the first time,we find that Cl^(-)ions in the electrolyte improve the photocurrent of a Si/In_(2)S_(3) photocathode by 50% at-0.6 V_(RHE).An in-situ X-ray photoelectron spectroscopy(XPS)characterization combined with the time-of-flight secondary-ion mass spectrometry by simulating photoelectrochemical conditions was used to investigate the interface charge transfer mechanism.The results suggest that there is an In_(2)^(+3)S_(3-x)(OH)_(2x)layer on the surface of In_(2)S_(3) in the phosphate buffer solution(PBS)electrolyte,which plays a role as an interface charge transfer mediator in the Si/In_(2)S_(3) photocathode.The In_(2)^(+3)S_(3-x)(OH)_(2x)surface layer becomes In_(2)^(+3)S_(3-x)(Cl)_(2x)in the PBS electrolyte with NaCl and accelerates the charge transfer rate at the In_(2)S_(3)/electrolyte interface.These results offer a new concept of regulating interface charge transfer mediator to enhance the performance of photoelectrocatalytic seawater splitting for hydrogen production.
基金This work was supported by the National Natural Science Foundation of China(Nos.21064006,21262032 and 21161018)the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(No.IRT1177)+2 种基金the Natural Science Foundation of Gansu Province(No.1010RJZA018)the Youth Foundation of Gansu Province(No.2011GS04735)NWNU-LKQN-11-32.
文摘A long wavelength emission fluorescent(612 nm)chemosensor with high selectivity for H_(2)PO_(4)^(−)ions was designed and synthesized according to the excited state intramolecular proton transfer(ESIPT).The sensor can exist in two tautomeric forms(‘keto’and‘enol’)in the presence of Fe^(3+)ion,Fe^(3+)may bind with the‘keto’form of the sensor.Furthermore,the in situ generated GY-Fe^(3+)ensemble could recover the quenched fluorescence upon the addition of H_(2)PO_(4)^(−)anion resulting in an off-on-type sensing with a detection limit of micromolar range in the same medium,and other anions,including F^(−),Cl^(−),Br^(−),I^(−),AcO^(−),HSO^(−)_(4),ClO^(−)_(4)and CN−had nearly no influence on the probing behavior.The test strips based on 2-[2-hydroxy-4-(diethylamino)phenyl]-1H-imidazo[4,5-b]phenazine and Fe^(3+)metal complex(GY-Fe^(3+))were fabricated,which could act as convenient and efficient H_(2)PO_(4)^(−)test kits.
基金Nature Science Foundation of Qinghai Province(2018-ZJ-945Q)NSFC(21573268)+1 种基金Joint Foundation of Salt Lake Chemical(U1607106)Instrument function development and technology innovation project of Chinese academy of sciences(2018g108)
文摘The microhydration structure of nickel sulfate aqueous solution has been determined via density functional theory (DFT) calculation and extended X-ray absorption fine structure (EXAFS) spectroscopy.The geometric optimization and energy calculation of nickel sulfate hydrated clusters of the molecular formula [NiSO4(H2O)n ]^0 (n=1-12) were determined via DFT using the B3LYP method.Several possible initial structures were considered for clusters of each size to locate the equilibrium geometry.Based on the DFT calculation,the favorable structure of Ni^2+ includes the six-coordinated form of [NiSO4(H2O)n ]^0 clusters.The results of hydration energy calculation suggest that the six-coordinated contact ion pair (CIP) is the stable configuration for small hydration clusters (n≤5),while the solvent-shared ion pair (SSIP) represents the favorable structure for medium hydration clusters (6≤n≤10).The solvent is separated by x water molecules (xSIP,x≥2 is the number of water molecule between Ni^2+ and SO4^2-) in larger hydration clusters (n≥11).The EXAFS analysis of the NiSO 4 aqueous solutions and NiSO4 ·6H2O solid established that Ni^2+ was surrounded by six water molecules tightly forming an octahedral structure in the first hydration shell,and no CIP was found from 0.70 mol/L to 2.22 mol/L (near saturation).The Ni-O distance and coordinated number were 2.040±0.020 and 6.0±1.0,respectively.These results are consistent with the DFT calculations for [NiSO4(H2O)n ]^0 clusters.DFT and EXAFS are powerful techniques that can be used to enhance the resolution of NiSO 4 solution microstructure.
文摘AF@MOF-808 incorporating the acriflavine(AF)dye into the nanocages of MOF-808 was constructed by one-pot hydrothermal method,whose crystallization,morphology and stability were characterized by the X-ray powder diffractometer(XRD),scanning electron microscope(SEM)and thermogravimetric analysis(TGA).AF@MOF-808 exhibits bright green light emission with the high quantum yield of 38.27%and can selectively detect Fe^(3+)ion and Cr_(2)O_(7)^(2-)anion from 12 kinds of metal ions or anions in the aqueous solution.
