圆具有优美的性质,研究发现,椭圆、双曲线与圆有着类似的优美性质,当椭圆和双曲线的焦点在x轴上时,圆、椭圆和双曲线关于“直径所对周角”的性质可以统一为“CE为直径的充要条件是k BC k BE=e^(2)-1”;关于“弦中点”的性质可以统一为“...圆具有优美的性质,研究发现,椭圆、双曲线与圆有着类似的优美性质,当椭圆和双曲线的焦点在x轴上时,圆、椭圆和双曲线关于“直径所对周角”的性质可以统一为“CE为直径的充要条件是k BC k BE=e^(2)-1”;关于“弦中点”的性质可以统一为“H为弦IJ中点的充要条件是k OH k IJ=e^(2)-1”;关于“切点和半径”的性质可以统一为“ML为切线(K为切点)的充要条件是k OK k ML=e^(2)-1”;当焦点在y轴上时,只需将e^(2)-1变换为关于a,b的关系式,再将a换为b,b换为a.圆、椭圆和双曲线以上三个类似的性质,可以做出统一的叙述,可以看作圆具有特殊性,椭圆和双曲线具有一般性,而从e^(2)-1的角度看,三者又具有统一性.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
Transition metal Ni anchored in carbon material represents outstanding 2e^(-) oxygen reduction reaction(ORR)catalytic selectivity,but enhancing the adsorption strength of intermediate*OOH to promote its selectivity re...Transition metal Ni anchored in carbon material represents outstanding 2e^(-) oxygen reduction reaction(ORR)catalytic selectivity,but enhancing the adsorption strength of intermediate*OOH to promote its selectivity remains a major challenge.Herein,the NiX/Ni@NCHS composite catalyst with heteroatom doping(O,S)is modulated by controlling partial pyrolysis strategies on honeycomb-like porous carbon to manipulate the electronic structure of the metal Ni.With the synergistic effect of honeycomb structure and O atom,NiO/Ni@NCHS-700 exhibits an exceptional H_(2)O_(2)selectivity of above 89.1%across a wide potential range from 0.1 to 0.6 V in an alkaline electrolyte,and an unexpected H_(2)O_(2)production rate up to 1.47 mol gcat^(-1) h^(-1)@0.2 V,which outperforms most of the state-of-the-art catalyst.Meanwhile,NiS/Ni@NCHS exhibits excellent electrocatalytic performance,with 2e^(-) ORR selectivity of 91.3%,H_(2)O_(2)yield of 1.85@0.3 V.Density functional theory simulations and experiments results reveal that the heteroatom doping(O,S)method has been employed to regulate the adsorption strength of Ni atoms with*OOH,and combined with the self-sacrificing template-assisted pyrolysis approach to improve the microstructure of catalysts and optimize the active site.The heteroatom doping method in this work provides significant guidance for promoting 2e^(-) ORR electrocatalysis to produce H_(2)O_(2).展开更多
Rationally manipulating surface reconstruction of catalysts for water oxidation,inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges.Herein,the introduction of[Cr(...Rationally manipulating surface reconstruction of catalysts for water oxidation,inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges.Herein,the introduction of[Cr(C_(2)O_(4))_(3)]^(3-)into NiFe LDHs by intercalation engineering to promote surface reconstruction achieves an advanced oxygen evolution reaction(OER)activity.In view of the weak electronegativity of Cr^(3+) in[Cr(C_(2)O_(4))_(3)]^(3-),the intercalation of[Cr(C_(2)O_(4))_(3)]^(3-)is expected to result in an electron-rich structure of Fe sites in NiFe LDHs,and higher valence state of Ni can be formed with the charge transfer between Fe and Ni.The optimized electronic structure of NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs with more active Ni^(3+) species and the expedited dynamic generation of Ni^(3+) (Fe)OOH phase during the OER process contributed to its excellent catalytic property,revealed by in situ X-ray absorption spectroscopy,Raman spectroscopy,and quasi-in situ X-ray photoelectron spectroscopy.With the modulated electronic structure of metal sites,NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs exhibited promoted OER property with a lower overpotential of 236 mV at the current density of 10 mA cm^(-2).This work illustrates the intercalation of conjugated anion to dynamically construct desired Ni^(3+) sites with the optimal electronic environment for improved OER electrocatalysis.展开更多
Results of oxidation 2-(N-acetylamine)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid oxygen depend on temperature. At 55℃?- 60℃, 2,4-di-tert-butylbicyclo(4,3,1)deca-4,6-dien-8-(N-acetylamine)-3,9-dion-1-oxa i...Results of oxidation 2-(N-acetylamine)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid oxygen depend on temperature. At 55℃?- 60℃, 2,4-di-tert-butylbicyclo(4,3,1)deca-4,6-dien-8-(N-acetylamine)-3,9-dion-1-oxa is formed. The constitution is based on dates of spectrums 1Н and 13С NMR. At 95℃?- 97℃, mixtures of 2,4-di-tert-butylbicyclo(4,3,1)deca-4,6-dien-8-(N-acetylamine)-3,9-dion-1-oxa and of 6,8-di-tert-butyl-3-(N-acetylamine)spiro(4,5)deca-1-oxa-5,8-dien-2,7-dione are produced. Structures are calculated by the method of Hartrii-Foka. Values of enthalpies and of entropies allow to assume dynamic isomerism.展开更多
The oxidative polycondensation reaction conditions of 2-[(2-hydroxyphenyliminomethylbenzylidene)amino- phenol](2-HPIMBAP)has been accomplished by using air O_2 and NaOCl oxidants in an aqueous alkaline medium between ...The oxidative polycondensation reaction conditions of 2-[(2-hydroxyphenyliminomethylbenzylidene)amino- phenol](2-HPIMBAP)has been accomplished by using air O_2 and NaOCl oxidants in an aqueous alkaline medium between 50-90℃.The optimum reaction conditions of the oxidative polycondensation and the main parameters of the process were established.At the optimum reaction conditions,yield of the products were found to be 67.72% and 61.49% for air O_2 and NaOCl oxidants respectively.The structures of the monomer ...展开更多
Investigation of the substitution process can provide a better understanding of the superconducting mechanisms in cuprous oxide materials. In this work the effects of substitution Lanthanum (La) for Gadolinium (Gd) on...Investigation of the substitution process can provide a better understanding of the superconducting mechanisms in cuprous oxide materials. In this work the effects of substitution Lanthanum (La) for Gadolinium (Gd) on the structure and oxygen content for x = 0.0 - 0.5 in the compound Gd1-xLaxBa2Cu3O7-δ (GLBCO-123 phase) have been investigated. Samples were synthesized by using a wet-mixing method from powders of Gd2O2, La2O2, BaO, CuO, and solution of HNO3. Based on the analysis of XRD data and SEM-EDXA, it confirms that the sample has formed the GLBCO-123 phase, as expected. It has been obtained that the lattice parameters a and c are increased while the parameter b is slightly decreased with increasing content of Lanthanum. The oxygen content slightly decreased and structure of the Gd1-xLaxBa2Cu3O7-δ phase changed from orthorhombic to tetragonal with increasing the content of Lanthanum.展开更多
The oxidative polycondensation reaction conditions of 4-[（4-hydroxybenzylidene） amino] phenol （4-HBAP） were studied with H2O2, air oxygen and NaOCl in an aqueous alkaline medium between 50 and 90℃. The structures...The oxidative polycondensation reaction conditions of 4-[（4-hydroxybenzylidene） amino] phenol （4-HBAP） were studied with H2O2, air oxygen and NaOCl in an aqueous alkaline medium between 50 and 90℃. The structures of the obtained monomer and polymer were confirmed by FT-IR, UV-Vis, 1H- and 13C-NMR and elemental analysis. The characterization was made by TG-DTA, size exclusion chromatography （SEC） and solubility tests. At the optimum reaction conditions, the yield of poly[4-（4-hydroxybenzylidene amino） phenol] （P-4-HBAP） was found to be 48.3% （for H2O2 oxidant）, 80.5% （for air O2 oxidant） and 86.4% （for NaOCl oxidant）. According to the SEC analysis, the number-average molecular weight （Mn）, weight-average molecular weight （Mw） and polydispersity index （PDI） values of P-4-HBAP was found to be 8950, 10970 g tool^-1 and 1.225, respectively, using H202; and l l610, 15190 g tool^-1 and 1.308 respectively, using air 02 and 7900, 9610 g mol^-1 and 1.216, respectively, using NaOC1. According to TG-DTA analyses, P-4-HBAP was more stable than 4-HBAP against thermal decomposition. The weight loss of P-4-HBAP was found to be 49.27% at 1000℃. The highest occupied molecular orbital （HOMO） and the lowest unoccupied molecular orbital （LUMO） values calculated from electrochemical measurement. Electrochemical energy gaps （Eg＇） of 4-HBAP and P-4-HBAP were found to be -5.46, -5.28; -2.26, -2.67; 3.20 and 2.61 eV, respectively. According to UV-Vis measurements, optical band gap （Eg） of 4-HBAP and P-4-HBAP were found to be 3.34 and 3.01 eV, respectively. Also, antimicrobial activities of 4-HBAP and P-4-HBAP were examined against selected some bacteria. The electrical conductivity of the polymer was measured after doping with iodine.展开更多
As the oxygen redox ability shows great effects on the catalytic performances of ceria-zirconia based materials,many strategies have been utilized to improve the oxygen storage capacity.Here in this study,we report a ...As the oxygen redox ability shows great effects on the catalytic performances of ceria-zirconia based materials,many strategies have been utilized to improve the oxygen storage capacity.Here in this study,we report a simple and facile approach to prepare a SO_(4)^(2-)-modified La,Y-doped ceria-zirconia material(SO/CZLY-f)with high oxygen storage capacity.Due to the additional redox process between SO_(4)^(2-)and S^(2-),oxygen storage capacity of SO/CZLY-f(745.3μmol O_(2)/g)is about 1.6 times higher than that of La,Ydoped ceria-zirconia material without SO_(4)^(2-)modification.Moreover,the catalytic activities and stability of the corresponding Pd-only three-way catalyst were measured.Compared to that of Pd@CZLY-f,the operation window of CO,full conversion temperature of HC and NO over Pd@SO/CZLY-f are obviously widened and lowered,respectively.After aging treatment at 1100℃for 4 h,the superiority of aged Pdloading composite is still maintained.展开更多
Promoting the oxygen reduction reaction(ORR)is critical for commercialization of intermediate-temperature solid oxide fuel cells(IT-SOFCs),where Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)−δ(SFM)is a promising cathode by working as ...Promoting the oxygen reduction reaction(ORR)is critical for commercialization of intermediate-temperature solid oxide fuel cells(IT-SOFCs),where Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)−δ(SFM)is a promising cathode by working as a mixed ionic and electronic conductor.In this work,doping of In^(3+)greatly increases the oxygen vacancy concentration and the content of adsorbed oxygen species in Sr_(2)Fe_(1.5)Mo_(0.5−x)InxO_(6−δ)(SFMInx),and thus effectively promotes the ORR performance.As a typical example,SFMIn_(0.1)reduces the polarization resistance(R_(p))from 0.089 to 0.046Ω∙cm^(2)at 800°C,which is superior to those doped with other metal elements.In addition,SFMIn0.1 increases the peak power density from 0.92 to 1.47 W∙cm^(−2)at 800°C with humidified H_(2)as the fuel,indicating that In3+doping at the Mo site can effectively improve the performance of SOFC cathode material.展开更多
Drastic surges in intracellular reactive oxygen species(ROS)induce cell apoptosis,while most chemotherapy drugs lead to the accumulation of ROS.Here,we constructed an organic compound,arsenical N-(4-(1,3,2-dithiarsina...Drastic surges in intracellular reactive oxygen species(ROS)induce cell apoptosis,while most chemotherapy drugs lead to the accumulation of ROS.Here,we constructed an organic compound,arsenical N-(4-(1,3,2-dithiarsinan-2-yl)phenyl)acrylamide(AAZ2),which could prompt the ROS to trigger mitochondrial-dependent apoptosis in gastric cancer(GC).Mechanistically,by targeting pyruvate dehydrogenase kinase 1(PDK1),AAZ2 caused metabolism alteration and the imbalance of redox homeostasis,followed by the inhibition of phosphoinositide-3-kinase(PI3K)/protein kinase B(AKT)/mammalian target of rapamycin(mTOR)pathway and leading to the activation of B-cell lymphoma 2(Bcl2)/Bcl2-associated X(Bax)/caspase-9(Cas9)/Cas3 cascades.Importantly,our in vivo data demonstrated that AAZ2 could inhibit the growth of GC xenograft.Overall,our data suggested that AAZ2 could contribute to metabolic abnormalities,leading to mitochondrial-dependent apoptosis by targeting PDK1 in GC.展开更多
The use of the internal magnetic field of ferromagnets can effectively promote charge separation and transfer(CST)in photoelectrochemical energy conversion.However,photoelectrochemical materials with a ferromagnetic f...The use of the internal magnetic field of ferromagnets can effectively promote charge separation and transfer(CST)in photoelectrochemical energy conversion.However,photoelectrochemical materials with a ferromagnetic field are scarce,and the internal magnetic field is negligible in nonferromagnetic mate-rials.To address this issue,we propose a rational method for preparing ferromagnetic TiO_(2)powder using controllable oxygen vacancies in anatase TiO_(2)with co-exposed{001}and{101}facets.Accordingly,an ex-cellent saturation magnetisation of 0.0014 emu/g in TiO_(2)is achieved owing to an asymmetric and uneven charge distribution.Compared with that of nonferromagnetic TiO_(2),the efficiency of photocatalytic hydro-gen generation of ferromagnetic TiO_(2)is improved by 0.64 times.The enhancement of photocatalytic hy-drogen generation is due to the different forces exerted on the electrons and holes in the magnetic field,which significantly improve the photogenerated CST efficiency of ferromagnetic TiO_(2).This result high-lights the significant role of the synergistic regulation of the crystal structure and defects in regulating the ferromagnetic characteristics of materials.The findings of this study provide guidance for leveraging point defects to promote CST for high-efficiency solar-energy conversion systems.展开更多
La0.15Sr0.85Ga0.3Fe0.7O3-δ (LSGFO) and La0.15Sr0.85Co0.3Fe0.7O3-δ (LSCFO) mixed oxygenion and electron conducting oxides were synthesized by using a combined EDTA and citrate complexing method, and the corresponding...La0.15Sr0.85Ga0.3Fe0.7O3-δ (LSGFO) and La0.15Sr0.85Co0.3Fe0.7O3-δ (LSCFO) mixed oxygenion and electron conducting oxides were synthesized by using a combined EDTA and citrate complexing method, and the corresponding dense membranes were fabricated. The properties of the oxide powders and membranes were characterized with combined SEM, XRD, H2-TPR, O2-TPD techniques, mechanical strength and oxygen permeation measurement. The results showed that LSGFO had much higher thermochemical stability than LSCFO due to the higher valence stability of Ga3+. After the temperature-programmed reduction by 5% H2 in Ar from 20°C to 1020°C, the basic perovskite structure of LSGFO was successfully preserved. LSGFO also favors the oxygen vacancy formation better than LSCFO. Oxygen permeation measurement demonstrated that LSGFO had higher oxygen permeation flux than LSCFO, but they had similar activation energy for oxygen transportation, with a value of 110 and 117 kJ · mol-1, respectively. The difference in oxygen permeation fluxes was correlated with the difference in oxygen vacancy concentrations for the two materials.展开更多
The permeability and stability of Sm_（0.7）Sr_（0.3）CoO_（3-δ）（SSCO） regarding the special requirements for carbon capture and storage（CCS） application were investigated.Pure CO_ was used as the sweep gas at 9...The permeability and stability of Sm_（0.7）Sr_（0.3）CoO_（3-δ）（SSCO） regarding the special requirements for carbon capture and storage（CCS） application were investigated.Pure CO_ was used as the sweep gas at 900 °C,leading to that the oxygen permeation flux decreases by about 34 %.Several cycles of changing the sweep gas between helium and CO_2 indicate the good reversibility of this degradation.Both carbonate formation and adsorption of CO_2 on the membrane surface are responsible for the degradation of the membrane performance.The better CO_2 resistance results from the substitution of Sm for Sr due to the higher acidity of Sm_2O_3（1.278） than that of Sr O（0.978） and a discontinuous layer of carbonate.展开更多
Solid electrolytes C%sSmo.2 xPrxO2-δ （x=0.02, 0.04, 0.06, 0.08） were prepared by citric-nitrate method. The microstructure and electrical properties of such materials were examined by X-ray diffraction （XRD）, ato...Solid electrolytes C%sSmo.2 xPrxO2-δ （x=0.02, 0.04, 0.06, 0.08） were prepared by citric-nitrate method. The microstructure and electrical properties of such materials were examined by X-ray diffraction （XRD）, atomic force microscopy （AFM）, Raman spec- troscopy （Raman）, X-ray photoelectron spectroscopy （XPS） and impedance spectroscopy analyses, Specifically, results from XRD analysis showed that samples calcined at 800 ℃ for 4 h possessed single-phase cubic fluorite structure, and the average grain size was found to be 36--45 nm. Further Raman spectral analysis indicated that oxygen vacancies should be present in the cubic fluorite struc- ture of Ce0.sSmo.laPr0.08Oe~, and Pr-doping seemed to increase their concentration significantly. AFM images showed that the grain size grew with the increase of Pr substitution. XPS analysis confirmed the existence of oxygen vacancies in the lattice of Ceo.sSmoA2Pro.osO2_~ in which Pr3＋ and Pr4＋ co-existed. AC impedance spectra indicated that the conductivity of Ceo.sSm0.2-xPrx02＋ increased with the increase of Pr-doping but the conduction activation energy decreased. Notably, it appeared that sample Ceo.sSmo.12Pro.o802-x （aaoooc=l.21xlO-z S/cm, Ea=0.77 eV） exhibited conductivity superior to Ceo.sSmo.2Ol.9 （aro0.c=2.22×10-3 S/cm, Ea= 1.02 eV） because it possessed higher conductivity and lower activation energy. At 600 ℃, the conductivity of Ce0.sSrno.12Pr0.0802m was 4.45 times higher than that of the un-doped material.展开更多
文摘圆具有优美的性质,研究发现,椭圆、双曲线与圆有着类似的优美性质,当椭圆和双曲线的焦点在x轴上时,圆、椭圆和双曲线关于“直径所对周角”的性质可以统一为“CE为直径的充要条件是k BC k BE=e^(2)-1”;关于“弦中点”的性质可以统一为“H为弦IJ中点的充要条件是k OH k IJ=e^(2)-1”;关于“切点和半径”的性质可以统一为“ML为切线(K为切点)的充要条件是k OK k ML=e^(2)-1”;当焦点在y轴上时,只需将e^(2)-1变换为关于a,b的关系式,再将a换为b,b换为a.圆、椭圆和双曲线以上三个类似的性质,可以做出统一的叙述,可以看作圆具有特殊性,椭圆和双曲线具有一般性,而从e^(2)-1的角度看,三者又具有统一性.
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Transition metal Ni anchored in carbon material represents outstanding 2e^(-) oxygen reduction reaction(ORR)catalytic selectivity,but enhancing the adsorption strength of intermediate*OOH to promote its selectivity remains a major challenge.Herein,the NiX/Ni@NCHS composite catalyst with heteroatom doping(O,S)is modulated by controlling partial pyrolysis strategies on honeycomb-like porous carbon to manipulate the electronic structure of the metal Ni.With the synergistic effect of honeycomb structure and O atom,NiO/Ni@NCHS-700 exhibits an exceptional H_(2)O_(2)selectivity of above 89.1%across a wide potential range from 0.1 to 0.6 V in an alkaline electrolyte,and an unexpected H_(2)O_(2)production rate up to 1.47 mol gcat^(-1) h^(-1)@0.2 V,which outperforms most of the state-of-the-art catalyst.Meanwhile,NiS/Ni@NCHS exhibits excellent electrocatalytic performance,with 2e^(-) ORR selectivity of 91.3%,H_(2)O_(2)yield of 1.85@0.3 V.Density functional theory simulations and experiments results reveal that the heteroatom doping(O,S)method has been employed to regulate the adsorption strength of Ni atoms with*OOH,and combined with the self-sacrificing template-assisted pyrolysis approach to improve the microstructure of catalysts and optimize the active site.The heteroatom doping method in this work provides significant guidance for promoting 2e^(-) ORR electrocatalysis to produce H_(2)O_(2).
基金support from the National Natural Science Foundation of China(51402100,21905088,21573066 and U19A2017)the Provincial Natural Science Foundation of Hunan(2020JJ5044,2022JJ10006)。
文摘Rationally manipulating surface reconstruction of catalysts for water oxidation,inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges.Herein,the introduction of[Cr(C_(2)O_(4))_(3)]^(3-)into NiFe LDHs by intercalation engineering to promote surface reconstruction achieves an advanced oxygen evolution reaction(OER)activity.In view of the weak electronegativity of Cr^(3+) in[Cr(C_(2)O_(4))_(3)]^(3-),the intercalation of[Cr(C_(2)O_(4))_(3)]^(3-)is expected to result in an electron-rich structure of Fe sites in NiFe LDHs,and higher valence state of Ni can be formed with the charge transfer between Fe and Ni.The optimized electronic structure of NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs with more active Ni^(3+) species and the expedited dynamic generation of Ni^(3+) (Fe)OOH phase during the OER process contributed to its excellent catalytic property,revealed by in situ X-ray absorption spectroscopy,Raman spectroscopy,and quasi-in situ X-ray photoelectron spectroscopy.With the modulated electronic structure of metal sites,NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs exhibited promoted OER property with a lower overpotential of 236 mV at the current density of 10 mA cm^(-2).This work illustrates the intercalation of conjugated anion to dynamically construct desired Ni^(3+) sites with the optimal electronic environment for improved OER electrocatalysis.
文摘Results of oxidation 2-(N-acetylamine)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid oxygen depend on temperature. At 55℃?- 60℃, 2,4-di-tert-butylbicyclo(4,3,1)deca-4,6-dien-8-(N-acetylamine)-3,9-dion-1-oxa is formed. The constitution is based on dates of spectrums 1Н and 13С NMR. At 95℃?- 97℃, mixtures of 2,4-di-tert-butylbicyclo(4,3,1)deca-4,6-dien-8-(N-acetylamine)-3,9-dion-1-oxa and of 6,8-di-tert-butyl-3-(N-acetylamine)spiro(4,5)deca-1-oxa-5,8-dien-2,7-dione are produced. Structures are calculated by the method of Hartrii-Foka. Values of enthalpies and of entropies allow to assume dynamic isomerism.
基金This work was supported by the Canakkale Onsekiz Mart University Scientific Research Projects Commission for financial support(No.2007/20).
文摘The oxidative polycondensation reaction conditions of 2-[(2-hydroxyphenyliminomethylbenzylidene)amino- phenol](2-HPIMBAP)has been accomplished by using air O_2 and NaOCl oxidants in an aqueous alkaline medium between 50-90℃.The optimum reaction conditions of the oxidative polycondensation and the main parameters of the process were established.At the optimum reaction conditions,yield of the products were found to be 67.72% and 61.49% for air O_2 and NaOCl oxidants respectively.The structures of the monomer ...
文摘Investigation of the substitution process can provide a better understanding of the superconducting mechanisms in cuprous oxide materials. In this work the effects of substitution Lanthanum (La) for Gadolinium (Gd) on the structure and oxygen content for x = 0.0 - 0.5 in the compound Gd1-xLaxBa2Cu3O7-δ (GLBCO-123 phase) have been investigated. Samples were synthesized by using a wet-mixing method from powders of Gd2O2, La2O2, BaO, CuO, and solution of HNO3. Based on the analysis of XRD data and SEM-EDXA, it confirms that the sample has formed the GLBCO-123 phase, as expected. It has been obtained that the lattice parameters a and c are increased while the parameter b is slightly decreased with increasing content of Lanthanum. The oxygen content slightly decreased and structure of the Gd1-xLaxBa2Cu3O7-δ phase changed from orthorhombic to tetragonal with increasing the content of Lanthanum.
基金This work was financially supported by the TUBITAK Grants Commission for a research grant(No.TBAG-2451(104T062)).
文摘The oxidative polycondensation reaction conditions of 4-[（4-hydroxybenzylidene） amino] phenol （4-HBAP） were studied with H2O2, air oxygen and NaOCl in an aqueous alkaline medium between 50 and 90℃. The structures of the obtained monomer and polymer were confirmed by FT-IR, UV-Vis, 1H- and 13C-NMR and elemental analysis. The characterization was made by TG-DTA, size exclusion chromatography （SEC） and solubility tests. At the optimum reaction conditions, the yield of poly[4-（4-hydroxybenzylidene amino） phenol] （P-4-HBAP） was found to be 48.3% （for H2O2 oxidant）, 80.5% （for air O2 oxidant） and 86.4% （for NaOCl oxidant）. According to the SEC analysis, the number-average molecular weight （Mn）, weight-average molecular weight （Mw） and polydispersity index （PDI） values of P-4-HBAP was found to be 8950, 10970 g tool^-1 and 1.225, respectively, using H202; and l l610, 15190 g tool^-1 and 1.308 respectively, using air 02 and 7900, 9610 g mol^-1 and 1.216, respectively, using NaOC1. According to TG-DTA analyses, P-4-HBAP was more stable than 4-HBAP against thermal decomposition. The weight loss of P-4-HBAP was found to be 49.27% at 1000℃. The highest occupied molecular orbital （HOMO） and the lowest unoccupied molecular orbital （LUMO） values calculated from electrochemical measurement. Electrochemical energy gaps （Eg＇） of 4-HBAP and P-4-HBAP were found to be -5.46, -5.28; -2.26, -2.67; 3.20 and 2.61 eV, respectively. According to UV-Vis measurements, optical band gap （Eg） of 4-HBAP and P-4-HBAP were found to be 3.34 and 3.01 eV, respectively. Also, antimicrobial activities of 4-HBAP and P-4-HBAP were examined against selected some bacteria. The electrical conductivity of the polymer was measured after doping with iodine.
基金Project supported by the Beijing Nova Program(Z181100006218030)Major State Research Development Program of Hebei province(20374202D)。
文摘As the oxygen redox ability shows great effects on the catalytic performances of ceria-zirconia based materials,many strategies have been utilized to improve the oxygen storage capacity.Here in this study,we report a simple and facile approach to prepare a SO_(4)^(2-)-modified La,Y-doped ceria-zirconia material(SO/CZLY-f)with high oxygen storage capacity.Due to the additional redox process between SO_(4)^(2-)and S^(2-),oxygen storage capacity of SO/CZLY-f(745.3μmol O_(2)/g)is about 1.6 times higher than that of La,Ydoped ceria-zirconia material without SO_(4)^(2-)modification.Moreover,the catalytic activities and stability of the corresponding Pd-only three-way catalyst were measured.Compared to that of Pd@CZLY-f,the operation window of CO,full conversion temperature of HC and NO over Pd@SO/CZLY-f are obviously widened and lowered,respectively.After aging treatment at 1100℃for 4 h,the superiority of aged Pdloading composite is still maintained.
基金acknowledge the Autonomous Region Key Research Project(No.2022D02D31)the Graduate Education Innovation Project(No.XJ2022G046)。
文摘Promoting the oxygen reduction reaction(ORR)is critical for commercialization of intermediate-temperature solid oxide fuel cells(IT-SOFCs),where Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)−δ(SFM)is a promising cathode by working as a mixed ionic and electronic conductor.In this work,doping of In^(3+)greatly increases the oxygen vacancy concentration and the content of adsorbed oxygen species in Sr_(2)Fe_(1.5)Mo_(0.5−x)InxO_(6−δ)(SFMInx),and thus effectively promotes the ORR performance.As a typical example,SFMIn_(0.1)reduces the polarization resistance(R_(p))from 0.089 to 0.046Ω∙cm^(2)at 800°C,which is superior to those doped with other metal elements.In addition,SFMIn0.1 increases the peak power density from 0.92 to 1.47 W∙cm^(−2)at 800°C with humidified H_(2)as the fuel,indicating that In3+doping at the Mo site can effectively improve the performance of SOFC cathode material.
基金supported by the Wuhan University Zhongnan Hospital Translational Medicine and Interdisciplinary Research Joint Fund(No.ZNJC201910),China.
文摘Drastic surges in intracellular reactive oxygen species(ROS)induce cell apoptosis,while most chemotherapy drugs lead to the accumulation of ROS.Here,we constructed an organic compound,arsenical N-(4-(1,3,2-dithiarsinan-2-yl)phenyl)acrylamide(AAZ2),which could prompt the ROS to trigger mitochondrial-dependent apoptosis in gastric cancer(GC).Mechanistically,by targeting pyruvate dehydrogenase kinase 1(PDK1),AAZ2 caused metabolism alteration and the imbalance of redox homeostasis,followed by the inhibition of phosphoinositide-3-kinase(PI3K)/protein kinase B(AKT)/mammalian target of rapamycin(mTOR)pathway and leading to the activation of B-cell lymphoma 2(Bcl2)/Bcl2-associated X(Bax)/caspase-9(Cas9)/Cas3 cascades.Importantly,our in vivo data demonstrated that AAZ2 could inhibit the growth of GC xenograft.Overall,our data suggested that AAZ2 could contribute to metabolic abnormalities,leading to mitochondrial-dependent apoptosis by targeting PDK1 in GC.
基金the China Postdoctoral Science Foundation(Grant No.2021M701829)It was also sup-ported by the Natural Science Foundation of Gansu Province in China(Grant No.22JR5RA484)+2 种基金Fundamental Research Funds for the Central University(Nos.lzujbky-2021-61 and SWU-KT22001)State Key Laboratory of New Ceramic and Fine Processing Ts-inghua University(No.KF202118)The authors would like to thank Tsinghua-Deqing Joint Research center for Materials Design and Industrial Innovation for the support.The authors would like to thank Shiyanjia Lab(www.shiyanjia.com)for the support provided for hydrogen generation,SS-SPV measurement,ESR test,DFT cal-culations,and modification polish.
文摘The use of the internal magnetic field of ferromagnets can effectively promote charge separation and transfer(CST)in photoelectrochemical energy conversion.However,photoelectrochemical materials with a ferromagnetic field are scarce,and the internal magnetic field is negligible in nonferromagnetic mate-rials.To address this issue,we propose a rational method for preparing ferromagnetic TiO_(2)powder using controllable oxygen vacancies in anatase TiO_(2)with co-exposed{001}and{101}facets.Accordingly,an ex-cellent saturation magnetisation of 0.0014 emu/g in TiO_(2)is achieved owing to an asymmetric and uneven charge distribution.Compared with that of nonferromagnetic TiO_(2),the efficiency of photocatalytic hydro-gen generation of ferromagnetic TiO_(2)is improved by 0.64 times.The enhancement of photocatalytic hy-drogen generation is due to the different forces exerted on the electrons and holes in the magnetic field,which significantly improve the photogenerated CST efficiency of ferromagnetic TiO_(2).This result high-lights the significant role of the synergistic regulation of the crystal structure and defects in regulating the ferromagnetic characteristics of materials.The findings of this study provide guidance for leveraging point defects to promote CST for high-efficiency solar-energy conversion systems.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China (Grant No. 59789201), the National Advanced Materials Committee of China (Grant No. 715-006-0122) and the Ministry of Science and Technology, China (Grant No. G1
文摘La0.15Sr0.85Ga0.3Fe0.7O3-δ (LSGFO) and La0.15Sr0.85Co0.3Fe0.7O3-δ (LSCFO) mixed oxygenion and electron conducting oxides were synthesized by using a combined EDTA and citrate complexing method, and the corresponding dense membranes were fabricated. The properties of the oxide powders and membranes were characterized with combined SEM, XRD, H2-TPR, O2-TPD techniques, mechanical strength and oxygen permeation measurement. The results showed that LSGFO had much higher thermochemical stability than LSCFO due to the higher valence stability of Ga3+. After the temperature-programmed reduction by 5% H2 in Ar from 20°C to 1020°C, the basic perovskite structure of LSGFO was successfully preserved. LSGFO also favors the oxygen vacancy formation better than LSCFO. Oxygen permeation measurement demonstrated that LSGFO had higher oxygen permeation flux than LSCFO, but they had similar activation energy for oxygen transportation, with a value of 110 and 117 kJ · mol-1, respectively. The difference in oxygen permeation fluxes was correlated with the difference in oxygen vacancy concentrations for the two materials.
基金financially supported by the National Natural Science Foundation of China (Nos.51174133,51274139 and 51225401)the Science and Technology Commission of Shanghai Municipality (No.11ZR1412900)
文摘The permeability and stability of Sm_（0.7）Sr_（0.3）CoO_（3-δ）（SSCO） regarding the special requirements for carbon capture and storage（CCS） application were investigated.Pure CO_ was used as the sweep gas at 900 °C,leading to that the oxygen permeation flux decreases by about 34 %.Several cycles of changing the sweep gas between helium and CO_2 indicate the good reversibility of this degradation.Both carbonate formation and adsorption of CO_2 on the membrane surface are responsible for the degradation of the membrane performance.The better CO_2 resistance results from the substitution of Sm for Sr due to the higher acidity of Sm_2O_3（1.278） than that of Sr O（0.978） and a discontinuous layer of carbonate.
基金Project supported by the National Natural Science Foundation of China(51272087)Science Research Foundation of Jilin Province(2014181)
文摘Solid electrolytes C%sSmo.2 xPrxO2-δ （x=0.02, 0.04, 0.06, 0.08） were prepared by citric-nitrate method. The microstructure and electrical properties of such materials were examined by X-ray diffraction （XRD）, atomic force microscopy （AFM）, Raman spec- troscopy （Raman）, X-ray photoelectron spectroscopy （XPS） and impedance spectroscopy analyses, Specifically, results from XRD analysis showed that samples calcined at 800 ℃ for 4 h possessed single-phase cubic fluorite structure, and the average grain size was found to be 36--45 nm. Further Raman spectral analysis indicated that oxygen vacancies should be present in the cubic fluorite struc- ture of Ce0.sSmo.laPr0.08Oe~, and Pr-doping seemed to increase their concentration significantly. AFM images showed that the grain size grew with the increase of Pr substitution. XPS analysis confirmed the existence of oxygen vacancies in the lattice of Ceo.sSmoA2Pro.osO2_~ in which Pr3＋ and Pr4＋ co-existed. AC impedance spectra indicated that the conductivity of Ceo.sSm0.2-xPrx02＋ increased with the increase of Pr-doping but the conduction activation energy decreased. Notably, it appeared that sample Ceo.sSmo.12Pro.o802-x （aaoooc=l.21xlO-z S/cm, Ea=0.77 eV） exhibited conductivity superior to Ceo.sSmo.2Ol.9 （aro0.c=2.22×10-3 S/cm, Ea= 1.02 eV） because it possessed higher conductivity and lower activation energy. At 600 ℃, the conductivity of Ce0.sSrno.12Pr0.0802m was 4.45 times higher than that of the un-doped material.
