The influences of pyrolytic conditions,including temperature,time,the flow ra te of air,and the heating rate,on the morphology,average size and specific su rface area of the NiO particles were investigated,and the com...The influences of pyrolytic conditions,including temperature,time,the flow ra te of air,and the heating rate,on the morphology,average size and specific su rface area of the NiO particles were investigated,and the composition and morph ologies of the products were characterized by using of XRD,SEM and BET. It is f ound that fibrous NiO particles were produced under the optimal conditions. A su itable range of pH for preparing dispersive precursors was chosen according to a nalysis of zeta potential. Based on the observations of NiO precursors growth an d SEM morphology of the precursor,the oriented attachment was proposed for the well-aligned growth of the NiO precursor fibres. The final product NiO inherits the morphology of the precursor.展开更多
Fine nickel(Ni) powders with controllable particle sizes were synthesized via the reduction of nickel hydrazine complex precursors of pure [Ni(N2H4)2]Cl2 and a mixture of [Ni(N2H4)2]Cl2 and [Ni(N2H4)3]Cl2 in aqueous s...Fine nickel(Ni) powders with controllable particle sizes were synthesized via the reduction of nickel hydrazine complex precursors of pure [Ni(N2H4)2]Cl2 and a mixture of [Ni(N2H4)2]Cl2 and [Ni(N2H4)3]Cl2 in aqueous solution. The mechanism of the formation of metallic Ni powders experiences the reduction of nickel hydroxide by hydrazine released from the ligand exchange reaction between nickel hydrazine complex and NaOH. In comparison with the method of preparing Ni powders from nickel salts,the method of making Ni powders via the reduction of nickel hydrazine complex precursors shows the advantages of using half dosage of hydrazine for complete reduction of nickel ions in solution,and the obtained Ni particles show less agglomeration and better dispersibility. Moreover,the average particle size of nickel powders can be controlled from 180 to 260 nm by adjusting the reaction molar ratio and concentration.展开更多
This work presents a study on the synthesis of LaNixCo1-xO3 perovskites via complex precursor methods. Perovskite oxides with the composition LaNixCo1-xO3 were synthesized by chelating precursor and polymeric precurso...This work presents a study on the synthesis of LaNixCo1-xO3 perovskites via complex precursor methods. Perovskite oxides with the composition LaNixCo1-xO3 were synthesized by chelating precursor and polymeric precursor methods using nickel and/or cobalt nitrates, lanthanum nitrate, ethylene glycol, citric acid, and EDTA as starting source. The obtained perovskite were characterized by thermogravimetric analysis, infrared spectroscopy, X-ray diffraction and the morphology of the samples were investigated by N2 adsorption experiments and average medium particle size. TG curves and FTIR spectra were particularly useful in establishing of the optimal calcination temperature of the precursor powders. X-ray diffraction patterns revealed the formation of the perovskite structure in all samples prepared by both synthesis method and after calcinations at 700℃. The results showed that the preparation method resulted in oxides with the intended structure. The specific surface area values were influenced by preparation method.展开更多
Proteolytic processing of the transmembrane amyloid precursor protein (APP) to aggregation-prone amyloid-β (Aβ) peptide underlies the development of Alzheimer’s disease.
Nowadays,Cu-based materials have attracted extensive attention as electrocatalysts,while the inherent reason of the filling of high anti-bonding state of Cu d band(3 d^(10)4 s^(1))makes it difficult to hybridize with ...Nowadays,Cu-based materials have attracted extensive attention as electrocatalysts,while the inherent reason of the filling of high anti-bonding state of Cu d band(3 d^(10)4 s^(1))makes it difficult to hybridize with O2 p band of oxygen intermediates during the adsorption process of oxygen evolution reaction(OER).To increase the efficiency of Cu-based electrocatalysts,efforts have been made to optimize the electronic structures and to create surface defects and hierarchical nanostructures with more exposed accessible active sites.Herein,we report a facile method for preparing CuO electrocatalysts with hierarchical nanostructures using the Cu-alanine complex as a precursor through room-temperature chemical precipitation and subsequent calcination in air.Investigations of products obtained at different calcination temperatures reveal the relationship between OER activities and the material characteristics such as specific surface areas,crystal growth orientations,and element components.The product obtained at 500℃exhibits the smallest overpotential of 290 mV in 1.0 mol/L KOH for electrocatalyzing OER.Combining with various characterizations of CuO electrocatalysts after OER activities,the possible catalytic mechanism and the influence factors of their OER performance are also discussed.展开更多
The system of geophysical shells （lithosphere, atmosphere, ionosphere） is considered as an open complex nonlinear system with dissipation where earthquake preparation could be regarded as a self-organizing process l...The system of geophysical shells （lithosphere, atmosphere, ionosphere） is considered as an open complex nonlinear system with dissipation where earthquake preparation could be regarded as a self-organizing process leading to the critical state of the system. The processes in atmosphere and ionosphere are considered from the point of view of non-equilibrium thermodynamics. The intensive ionization of boundary layer of atmosphere （probably provided by radon in occasion of earthquake preparation） gives start to the synergetic sequence of coupling processes where the ionosphere and even magnetosphere are the last links in the chain of interactions. Every anomaly observed in different geophysical fields （surface temperature, latent heat flux, electromagnetic emissions, variations in ionosphere, particle precipitation, etc.） is not considered as an individual process but the part of the self-organizing process, the final goal of which is the reaching of the point of the maximum entropy. Radon anomaly before the Kobe earthquake is considered as a perfect example to satisfy the formal seismological determination of the earthquake precursor. What is genetically connected with radon through the ionization process can also be regarded as a precursor. The problem of co-seismic variations of the discussed parameters of atmosphere and ionosphere is considered as well.展开更多
Precursors were prepared by solid state chemical reaction between LaCl_3 and C_2H_2O_4·2H_2O or NH_4HCO_3 at ambient temperature. Differential temperature analysis (DTA) and thermogravimetric analysis (TGA) were ...Precursors were prepared by solid state chemical reaction between LaCl_3 and C_2H_2O_4·2H_2O or NH_4HCO_3 at ambient temperature. Differential temperature analysis (DTA) and thermogravimetric analysis (TGA) were used to determine the decomposing temperature. Oxide (La_2O_3) was obtained by decomposing the precursor for about 2.5 h. X-ray diffraction (XRD), scanning electronic microscope (SEM) and ZETA potentiometer were respectively used to analyze the composition, morphology and size distribution of the products. The results show that La_2O_3 prepared by LaCl_3 and C_2H_2O_4·2H_2O is of ball-like shape and the diameter of particles (95%) is below 50 nm, while La_2O_3 prepared by LaCl_3 and NH_4HCO_3 is net-like.展开更多
文摘The influences of pyrolytic conditions,including temperature,time,the flow ra te of air,and the heating rate,on the morphology,average size and specific su rface area of the NiO particles were investigated,and the composition and morph ologies of the products were characterized by using of XRD,SEM and BET. It is f ound that fibrous NiO particles were produced under the optimal conditions. A su itable range of pH for preparing dispersive precursors was chosen according to a nalysis of zeta potential. Based on the observations of NiO precursors growth an d SEM morphology of the precursor,the oriented attachment was proposed for the well-aligned growth of the NiO precursor fibres. The final product NiO inherits the morphology of the precursor.
基金Projects(50674060, 50734005, 20601016) supported by the National Natural Science Foundation of ChinaProjects(2007CB613506, 2007CB613505) supported by the National Basic Research Program of China
文摘Fine nickel(Ni) powders with controllable particle sizes were synthesized via the reduction of nickel hydrazine complex precursors of pure [Ni(N2H4)2]Cl2 and a mixture of [Ni(N2H4)2]Cl2 and [Ni(N2H4)3]Cl2 in aqueous solution. The mechanism of the formation of metallic Ni powders experiences the reduction of nickel hydroxide by hydrazine released from the ligand exchange reaction between nickel hydrazine complex and NaOH. In comparison with the method of preparing Ni powders from nickel salts,the method of making Ni powders via the reduction of nickel hydrazine complex precursors shows the advantages of using half dosage of hydrazine for complete reduction of nickel ions in solution,and the obtained Ni particles show less agglomeration and better dispersibility. Moreover,the average particle size of nickel powders can be controlled from 180 to 260 nm by adjusting the reaction molar ratio and concentration.
文摘This work presents a study on the synthesis of LaNixCo1-xO3 perovskites via complex precursor methods. Perovskite oxides with the composition LaNixCo1-xO3 were synthesized by chelating precursor and polymeric precursor methods using nickel and/or cobalt nitrates, lanthanum nitrate, ethylene glycol, citric acid, and EDTA as starting source. The obtained perovskite were characterized by thermogravimetric analysis, infrared spectroscopy, X-ray diffraction and the morphology of the samples were investigated by N2 adsorption experiments and average medium particle size. TG curves and FTIR spectra were particularly useful in establishing of the optimal calcination temperature of the precursor powders. X-ray diffraction patterns revealed the formation of the perovskite structure in all samples prepared by both synthesis method and after calcinations at 700℃. The results showed that the preparation method resulted in oxides with the intended structure. The specific surface area values were influenced by preparation method.
文摘Proteolytic processing of the transmembrane amyloid precursor protein (APP) to aggregation-prone amyloid-β (Aβ) peptide underlies the development of Alzheimer’s disease.
基金supported by the National Natural Science Foundation of China(NSFC,Nos.U1904215,21671170,21673203,21805192 and 21875207)the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP)+5 种基金the Six Talent Plan(No.2015-XCL-030)the Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110735)China Postdoctoral Science Foundation(No.2020M671612)Jiangsu Province Postdoctoral Science Foundation(No.2020Z082)Excellent Doctoral Dissertation of Yangzhou University and Undergraduate Scientific Research Innovation Projects in Jiangsu Province(No.201911117036Z)the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘Nowadays,Cu-based materials have attracted extensive attention as electrocatalysts,while the inherent reason of the filling of high anti-bonding state of Cu d band(3 d^(10)4 s^(1))makes it difficult to hybridize with O2 p band of oxygen intermediates during the adsorption process of oxygen evolution reaction(OER).To increase the efficiency of Cu-based electrocatalysts,efforts have been made to optimize the electronic structures and to create surface defects and hierarchical nanostructures with more exposed accessible active sites.Herein,we report a facile method for preparing CuO electrocatalysts with hierarchical nanostructures using the Cu-alanine complex as a precursor through room-temperature chemical precipitation and subsequent calcination in air.Investigations of products obtained at different calcination temperatures reveal the relationship between OER activities and the material characteristics such as specific surface areas,crystal growth orientations,and element components.The product obtained at 500℃exhibits the smallest overpotential of 290 mV in 1.0 mol/L KOH for electrocatalyzing OER.Combining with various characterizations of CuO electrocatalysts after OER activities,the possible catalytic mechanism and the influence factors of their OER performance are also discussed.
基金funding from the European Union Seventh Framework Program (FP7/20017-2013)under grant agreement No.263502- -PRE-EARTHQUAKES project:Processing Russian and European EARTH observations for earthquake precursors studies
文摘The system of geophysical shells （lithosphere, atmosphere, ionosphere） is considered as an open complex nonlinear system with dissipation where earthquake preparation could be regarded as a self-organizing process leading to the critical state of the system. The processes in atmosphere and ionosphere are considered from the point of view of non-equilibrium thermodynamics. The intensive ionization of boundary layer of atmosphere （probably provided by radon in occasion of earthquake preparation） gives start to the synergetic sequence of coupling processes where the ionosphere and even magnetosphere are the last links in the chain of interactions. Every anomaly observed in different geophysical fields （surface temperature, latent heat flux, electromagnetic emissions, variations in ionosphere, particle precipitation, etc.） is not considered as an individual process but the part of the self-organizing process, the final goal of which is the reaching of the point of the maximum entropy. Radon anomaly before the Kobe earthquake is considered as a perfect example to satisfy the formal seismological determination of the earthquake precursor. What is genetically connected with radon through the ionization process can also be regarded as a precursor. The problem of co-seismic variations of the discussed parameters of atmosphere and ionosphere is considered as well.
文摘Precursors were prepared by solid state chemical reaction between LaCl_3 and C_2H_2O_4·2H_2O or NH_4HCO_3 at ambient temperature. Differential temperature analysis (DTA) and thermogravimetric analysis (TGA) were used to determine the decomposing temperature. Oxide (La_2O_3) was obtained by decomposing the precursor for about 2.5 h. X-ray diffraction (XRD), scanning electronic microscope (SEM) and ZETA potentiometer were respectively used to analyze the composition, morphology and size distribution of the products. The results show that La_2O_3 prepared by LaCl_3 and C_2H_2O_4·2H_2O is of ball-like shape and the diameter of particles (95%) is below 50 nm, while La_2O_3 prepared by LaCl_3 and NH_4HCO_3 is net-like.
