To achieve the controllable release of energy of nitrocellulose-based propellants,this paper combines the cellulose-based nanocomposites aqueous coating(Surelease®-NC)with fluidized bed coating equipment to succe...To achieve the controllable release of energy of nitrocellulose-based propellants,this paper combines the cellulose-based nanocomposites aqueous coating(Surelease®-NC)with fluidized bed coating equipment to successfully prepare the coated spherical propellant for the first time.The effects of fluidized bed coating temperature,air velocity,flow speed and atomization pressure on the adhesion rate,coating integrity and coating uniformity of the coated spherical propellant were investigated,and the preparation of coated spherical propellant with homogeneous size and structural integrity was achieved for the first time.The microscopic morphology,chemical structure,water vapor adsorption behavior,combustion performance,and ageing resistance property of the coated spherical propellant were systematically investigated by,Fourier transforms infrared spectroscopy(FTIR),Micro confocal raman spectrometer,field scanning electron microscopy(SEM),dynamic vapor adsorption techniques,and closed bomb test,confirming the surface core-shell structure and the tightly bonded interfacial structure of coated spherical propellant.Meanwhile,the coated spherical propellant has good hygroscopic,excellent progressive burning and long storage stability.展开更多
The three-dimensional hierarchical CuO and Au nanoparticles were synthesized by the hydrothermal method, respectively. The hierarchical CuO and the Au nanoparticles samples were characterized by X-ray diffraction and ...The three-dimensional hierarchical CuO and Au nanoparticles were synthesized by the hydrothermal method, respectively. The hierarchical CuO and the Au nanoparticles samples were characterized by X-ray diffraction and scanning electronic microscope, respectively. The as-synthesized CuO was assembled regularly from the nanosheets with thickness of 100 nm. The size of Au nanoparticles ranged from 50 to 200 nm. The hierarchical CuO gas sensors modified by different concentration of gold were fabricated. All the Au-loaded CuO gas sensors enhanced the response to ethanol and xylene while reducing the response to methanol, acetone, and formaldehyde. The results indicate that the Au nanoparticles prepared with PVP as surfactant can improve the selectivity of CuO gas sensors to ethanol gas for other common organic volatile gases. The improvement of gas sensing is mainly attributed to the different catalytic efficiency of the Au nanoparticles for different reactions. Meanwhile, the related mechanisms are discussed.展开更多
[Objectives] This study was conducted to study early reproduction techniques of yellow catfish(Pelteobagrus fulvidraco) in Jianghan Plain. [Methods] Parents of P. fulvidraco were cultured by the methods of artificial ...[Objectives] This study was conducted to study early reproduction techniques of yellow catfish(Pelteobagrus fulvidraco) in Jianghan Plain. [Methods] Parents of P. fulvidraco were cultured by the methods of artificial temperature control and nutrition enhancement. [Results] After culture, the body weight, gonad weight, maturity coefficient and egg diameter of P. fulvidraco increased gradually. Up to April 30, the gonad weight of the female parents of P. fulvidraco cultured in greenhouses was significantly higher than that of the parents under natural conditions(P<0.05), 54% higher than that of the parents naturally cultured at the same period;the maturity coefficient of the parents cultured under strengthened conditions was also significantly higher than that of the parents under natural conditions at the same period(P<0.05);and the ovaries of the strengthened parents were orange yellow and full of eggs, and the number of eggs per fish was relatively high. In early May, the parents cultured under strengthened conditions were induced to spawn artificially. The average induced spawning rate and fertilization rate reached 86.7% and 71.6%, respectively, reaching the respective normal level. The gonad maturity of P. fulvidraco cultured under strengthened conditions was 15 d earlier than that under natural conditions, resulting in mass production of early-propagated larvae of P. fulvidraco. [Conclusions] In Jianghan plain area, artificial propagation can be achieved in early May by means of artificial temperature control and strengthened culture, which is 20 d ahead of natural conditions.展开更多
Mg_(3)Sb_(2)-based thermoelectric materials have been the focus of widespread investigations as promising candidates for the harvesting of waste heat.Interface stability and service performance are key points for the ...Mg_(3)Sb_(2)-based thermoelectric materials have been the focus of widespread investigations as promising candidates for the harvesting of waste heat.Interface stability and service performance are key points for the commercial applications of these materials.We utilized Mg_(4.3)Sb_(3)Ni as a barrier layer to improve the thermal stability of Mg 3 Sb 2-based devices.However,its intrinsic high resistivity contributed nega-tively to the desired performance of the device.In this work,we investigated two other Mg-Sb-Ni ternary phases,MgSbNi and MgSbNi_(2),as new barrier layer materials to connect with Mg_(3.2)Sb_(2)Y_(0.05).The results show that the efficiency of the Mg_(1.2)SbNi/Mg_(3.2)Sb_(2)Y_(0.05)/Mg_(1.2)SbNi joint is increased by 33%relative to the higher Mg-content barriers due to lower resistivity.The system exhibited good interfacial compatibility and showed little change with aging at 673 K for 20 days.展开更多
Co_(0.9)Cu_(0.1)Si alloy was prepared by mechanical alloying method.Nitrogen-doped graphene(NG)and nitrogen–sulfur codoped graphene(NSG)were prepared by hydrothermal method.5 wt%graphene oxide,NG and NSG were doped i...Co_(0.9)Cu_(0.1)Si alloy was prepared by mechanical alloying method.Nitrogen-doped graphene(NG)and nitrogen–sulfur codoped graphene(NSG)were prepared by hydrothermal method.5 wt%graphene oxide,NG and NSG were doped into Co_(0.9)Cu_(0.1)Si alloy,respectively,by ball milling to improve the electrochemical hydrogen storage performance of the composite material.X-ray diffraction and scanning electron microscopy were used to characterize the structure and morphology of the composite material,and the LAND battery test system and three-electrode battery system were used to test the electrochemical performance of the composite material.The composite material showed better discharge capacity and better cycle stability than the pristine alloy.In addition,in order to study the optimal ratio of NSG,3%,5%,7%and 10%of NSG were doped into Co_(0.9)Cu_(0.1)Si alloy,respectively.Co_(0.9)Cu_(0.1)Si alloy doped with 5%NSG had the best performance among all the samples.The best discharge capacity was 580.1 mAh/g,and its highest capacity retention rate was 64.1%.The improvement in electrochemical hydrogen storage performance can be attributed to two aspects.On the one hand,the electrocatalytic performance of graphene is improved by co-doping nitrogen and sulfur,on the other hand,graphene has excellent electrical conductivity.展开更多
Gaseous peroxides play important roles in atmospheric chemistry. To understand the pathways of the formation and removal of peroxides, atmospheric peroxide concentrations and their controlling factors were measured fr...Gaseous peroxides play important roles in atmospheric chemistry. To understand the pathways of the formation and removal of peroxides, atmospheric peroxide concentrations and their controlling factors were measured from 7:00 to 20:00 in September, October, and November 2013 at a heavily trafficked residential site in Beijing, China, with average concentrations of hydrogen peroxide(H2O2) and methyl hydroperoxide(MHP) at 0.55 ppb and 0.063 ppb, respectively. H2O2 concentrations were higher in the afternoon and lower in the morning and evening, while MHP concentrations did not exhibit a regular diurnal pattern. Both H2O2 and MHP concentrations increased at dusk in most cases. Both peroxides displayed monthly variations with higher concentrations in September. These results suggested that photochemical activity was the main controlling factor on variations of H2O2 concentrations during the measurement period. Increasing concentrations of volatile organic compounds emitted by motor vehicles were important contributors to H2O2 and MHP enrichment. High levels of H2O2 and MHP concentrations which occurred during the measurement period probably resulted from the transport of a polluted air mass with high water vapor content passing over the Bohai Bay, China.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.22005143)Young Elite Scientists Sponsorship Program by CAST (Grant No.2022QNRC001)。
文摘To achieve the controllable release of energy of nitrocellulose-based propellants,this paper combines the cellulose-based nanocomposites aqueous coating(Surelease®-NC)with fluidized bed coating equipment to successfully prepare the coated spherical propellant for the first time.The effects of fluidized bed coating temperature,air velocity,flow speed and atomization pressure on the adhesion rate,coating integrity and coating uniformity of the coated spherical propellant were investigated,and the preparation of coated spherical propellant with homogeneous size and structural integrity was achieved for the first time.The microscopic morphology,chemical structure,water vapor adsorption behavior,combustion performance,and ageing resistance property of the coated spherical propellant were systematically investigated by,Fourier transforms infrared spectroscopy(FTIR),Micro confocal raman spectrometer,field scanning electron microscopy(SEM),dynamic vapor adsorption techniques,and closed bomb test,confirming the surface core-shell structure and the tightly bonded interfacial structure of coated spherical propellant.Meanwhile,the coated spherical propellant has good hygroscopic,excellent progressive burning and long storage stability.
基金Project supported by the Provincial Natural Science Foundation of Gansu (No. 1606RJZA026)the Scientific and Technological Project of Chengguan District of Lanzhou (No. 2016-2-4)Institute of Sensor Technology, Gansu Academy of Science
文摘The three-dimensional hierarchical CuO and Au nanoparticles were synthesized by the hydrothermal method, respectively. The hierarchical CuO and the Au nanoparticles samples were characterized by X-ray diffraction and scanning electronic microscope, respectively. The as-synthesized CuO was assembled regularly from the nanosheets with thickness of 100 nm. The size of Au nanoparticles ranged from 50 to 200 nm. The hierarchical CuO gas sensors modified by different concentration of gold were fabricated. All the Au-loaded CuO gas sensors enhanced the response to ethanol and xylene while reducing the response to methanol, acetone, and formaldehyde. The results indicate that the Au nanoparticles prepared with PVP as surfactant can improve the selectivity of CuO gas sensors to ethanol gas for other common organic volatile gases. The improvement of gas sensing is mainly attributed to the different catalytic efficiency of the Au nanoparticles for different reactions. Meanwhile, the related mechanisms are discussed.
基金Supported by The Technological Innovation Special Project of Hubei Province(2018ABA104)
文摘[Objectives] This study was conducted to study early reproduction techniques of yellow catfish(Pelteobagrus fulvidraco) in Jianghan Plain. [Methods] Parents of P. fulvidraco were cultured by the methods of artificial temperature control and nutrition enhancement. [Results] After culture, the body weight, gonad weight, maturity coefficient and egg diameter of P. fulvidraco increased gradually. Up to April 30, the gonad weight of the female parents of P. fulvidraco cultured in greenhouses was significantly higher than that of the parents under natural conditions(P<0.05), 54% higher than that of the parents naturally cultured at the same period;the maturity coefficient of the parents cultured under strengthened conditions was also significantly higher than that of the parents under natural conditions at the same period(P<0.05);and the ovaries of the strengthened parents were orange yellow and full of eggs, and the number of eggs per fish was relatively high. In early May, the parents cultured under strengthened conditions were induced to spawn artificially. The average induced spawning rate and fertilization rate reached 86.7% and 71.6%, respectively, reaching the respective normal level. The gonad maturity of P. fulvidraco cultured under strengthened conditions was 15 d earlier than that under natural conditions, resulting in mass production of early-propagated larvae of P. fulvidraco. [Conclusions] In Jianghan plain area, artificial propagation can be achieved in early May by means of artificial temperature control and strengthened culture, which is 20 d ahead of natural conditions.
基金supported by the National Science Foundation of China(Grant No.52202277)the Special Project of Science and Technology Cooperation and Exchange of Shanxi Province(Grant No.202104041101007).
文摘Mg_(3)Sb_(2)-based thermoelectric materials have been the focus of widespread investigations as promising candidates for the harvesting of waste heat.Interface stability and service performance are key points for the commercial applications of these materials.We utilized Mg_(4.3)Sb_(3)Ni as a barrier layer to improve the thermal stability of Mg 3 Sb 2-based devices.However,its intrinsic high resistivity contributed nega-tively to the desired performance of the device.In this work,we investigated two other Mg-Sb-Ni ternary phases,MgSbNi and MgSbNi_(2),as new barrier layer materials to connect with Mg_(3.2)Sb_(2)Y_(0.05).The results show that the efficiency of the Mg_(1.2)SbNi/Mg_(3.2)Sb_(2)Y_(0.05)/Mg_(1.2)SbNi joint is increased by 33%relative to the higher Mg-content barriers due to lower resistivity.The system exhibited good interfacial compatibility and showed little change with aging at 673 K for 20 days.
基金This work is financially supported by the National Key R&D Program of China(No.2017YFE0198100)the Jilin Province Development Program of Science and Technology(Nos.20210509065RQ,20200401031GX)+3 种基金the Natural Science Foundation of Jilin Province(Nos.20200201254JC,20200201094JC)the Natural Science Foundation of Chongqing City(No.cstc2021jcyjmsxmX0243)the Research Project of the Education Department of Jilin Province(No.JJKH20220761KJ)the Scientific and Technological Project of Jilin Provincial Department of Education(No.JJKH20220763KJ).
文摘Co_(0.9)Cu_(0.1)Si alloy was prepared by mechanical alloying method.Nitrogen-doped graphene(NG)and nitrogen–sulfur codoped graphene(NSG)were prepared by hydrothermal method.5 wt%graphene oxide,NG and NSG were doped into Co_(0.9)Cu_(0.1)Si alloy,respectively,by ball milling to improve the electrochemical hydrogen storage performance of the composite material.X-ray diffraction and scanning electron microscopy were used to characterize the structure and morphology of the composite material,and the LAND battery test system and three-electrode battery system were used to test the electrochemical performance of the composite material.The composite material showed better discharge capacity and better cycle stability than the pristine alloy.In addition,in order to study the optimal ratio of NSG,3%,5%,7%and 10%of NSG were doped into Co_(0.9)Cu_(0.1)Si alloy,respectively.Co_(0.9)Cu_(0.1)Si alloy doped with 5%NSG had the best performance among all the samples.The best discharge capacity was 580.1 mAh/g,and its highest capacity retention rate was 64.1%.The improvement in electrochemical hydrogen storage performance can be attributed to two aspects.On the one hand,the electrocatalytic performance of graphene is improved by co-doping nitrogen and sulfur,on the other hand,graphene has excellent electrical conductivity.
基金supported by the International Cooperation Project of MOST(No.2012DFG90290)the National Natural Science Foundation of China(No.4225001046)+1 种基金National Department Public Benefit Research Foundation(No.201509014)the Basic Foundation for Public Benefit-Research Academies from Centre Government(No.2010KYYW02)
文摘Gaseous peroxides play important roles in atmospheric chemistry. To understand the pathways of the formation and removal of peroxides, atmospheric peroxide concentrations and their controlling factors were measured from 7:00 to 20:00 in September, October, and November 2013 at a heavily trafficked residential site in Beijing, China, with average concentrations of hydrogen peroxide(H2O2) and methyl hydroperoxide(MHP) at 0.55 ppb and 0.063 ppb, respectively. H2O2 concentrations were higher in the afternoon and lower in the morning and evening, while MHP concentrations did not exhibit a regular diurnal pattern. Both H2O2 and MHP concentrations increased at dusk in most cases. Both peroxides displayed monthly variations with higher concentrations in September. These results suggested that photochemical activity was the main controlling factor on variations of H2O2 concentrations during the measurement period. Increasing concentrations of volatile organic compounds emitted by motor vehicles were important contributors to H2O2 and MHP enrichment. High levels of H2O2 and MHP concentrations which occurred during the measurement period probably resulted from the transport of a polluted air mass with high water vapor content passing over the Bohai Bay, China.