Through improving the aging process during synthesis of the support, γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the ...Through improving the aging process during synthesis of the support, γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the reaction temperature, the first aging temperature and the second aging temperature, were investigated. The textural properties of γ-Al2O3 were characterized by means of N2 adsorption-desorption isotherms, X-ray powder diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared （FTIR） spectroscopy and thermogravimetry （TG）. The experimental results indicated that AACH and amorphous A1OOH were the precursors of alumina, which were formed via precipitation from solutions after reaction of aluminum sulphate with ammonium hydrogen carbonate. The precursor nanocrystallites grew and re-assembled during the secondary reforming process, which resulted in an increased pore size and pore volume and a decreased bulk density. The as-synthesized γ-Al2O3 materials featured meso/macroporosity, large pore volume （2.175 cm^3/g）, high surface area （237.8 m^2/g）, and low bulk density （0.284 g/mL）.展开更多
The development of single-component white emitters for white light-emitting diodes(WLEDs)remains challenging.Herein,a rare earth-free white light-emitting composite is developed by assembling blue-emitting carbon dots...The development of single-component white emitters for white light-emitting diodes(WLEDs)remains challenging.Herein,a rare earth-free white light-emitting composite is developed by assembling blue-emitting carbon dots(CDs)and yellow-emitting Cs_(2)InCl_(5)·H_(2)O:Sb^(3+)metal halide crystals via a facile liquid-liquid diffusion-assisted crystallization approach.The encapsulation mechanism is then analyzed.Depending on the ratios of blue/yellow emitters,these luminescent composites exhibit white light emission with tunable cold and warm hues.The composites also possess prominent ultraviolet resistance,thermal tolerance,and good stability at about 200°C.By employing such“CDs in metal halide”composites as a converter,a WLED is successfully fabricated with a high color rendering index of 93.6,benefiting from the assembled blue and yellow broadband emission.With this strategy,the developed composites show great promise in next-generation WLED lighting.展开更多
In this study, we used the crystal structure search method and first-principles calculations to systematically explore the highpressure phase diagrams of the TaAs family （NbP, NbAs, TaP, and TaAs）. Our calculation r...In this study, we used the crystal structure search method and first-principles calculations to systematically explore the highpressure phase diagrams of the TaAs family （NbP, NbAs, TaP, and TaAs）. Our calculation results show that NbAs and TaAs have similar phase diagrams, the same structural phase transition sequence I41md→Pδm2→}P21/c→Pm3m, and slightly different transition pressures. The phase transition sequence of NbP and TaP differs somewhat from that of NbAs and TaAs, in which new structures emerge, such as the Cmcm structure in NbP and the Pmmn structure in TaP. Interestingly, we found that in the electronic structure of the high-pressure phase Pδm2-NbAs, there are coexisting Weyl points and triple degenerate points, similar to those found in high-pressure Pδm2-TaAs.展开更多
In this paper the theoretical model is built for ZEpHyR(ZARM Experimental Hybrid Rocket) main engine which is being developed at ZARM institute,Bremen,Germany.The theoretical model is used to estimate the temperature ...In this paper the theoretical model is built for ZEpHyR(ZARM Experimental Hybrid Rocket) main engine which is being developed at ZARM institute,Bremen,Germany.The theoretical model is used to estimate the temperature of exhaust gas.The Conjugate Gradient Method(CGM) with Adjoint Problem for Function Estimation iterative technique is used to solve the Inverse Heat Conduction Problem(IHCP) to estimate the heat flux and internal wall temperature at the throat section of the nozzle.Bartz equation is used to calculate the convective heat transfer coefficient.The exhaust gas temperature is determined using the estimated heat flux,the wall temperature at internal surface of nozzle and the heat transfer coefficient.The accuracy of CGM iterative scheme to solve the IHCP is also investigated and its results are presented.展开更多
基金the financial support by the Natural Science Foundation of Liaoning Province of China (Grant No. 2013020122)the National Natural Science Foundationof China (Grant No. 21076100 and 51308045)the financial support by the PetroChina Company Limited (Grant No. 10-01A-01-01-01)
文摘Through improving the aging process during synthesis of the support, γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the reaction temperature, the first aging temperature and the second aging temperature, were investigated. The textural properties of γ-Al2O3 were characterized by means of N2 adsorption-desorption isotherms, X-ray powder diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared （FTIR） spectroscopy and thermogravimetry （TG）. The experimental results indicated that AACH and amorphous A1OOH were the precursors of alumina, which were formed via precipitation from solutions after reaction of aluminum sulphate with ammonium hydrogen carbonate. The precursor nanocrystallites grew and re-assembled during the secondary reforming process, which resulted in an increased pore size and pore volume and a decreased bulk density. The as-synthesized γ-Al2O3 materials featured meso/macroporosity, large pore volume （2.175 cm^3/g）, high surface area （237.8 m^2/g）, and low bulk density （0.284 g/mL）.
基金supported by the National Natural Science Foundations of China (51961145101)Guangzhou Science & Technology Project (202007020005)+3 种基金the Project Supported by Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme (GDUPS, 2018) for Prof. Bingfu Leithe National Key R&D Program of China (2020YFB0407902)Guangdong Provincial Science & Technology Project (2021A0505050006 and 2021B0707010003)Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams (2021KJ122)。
文摘The development of single-component white emitters for white light-emitting diodes(WLEDs)remains challenging.Herein,a rare earth-free white light-emitting composite is developed by assembling blue-emitting carbon dots(CDs)and yellow-emitting Cs_(2)InCl_(5)·H_(2)O:Sb^(3+)metal halide crystals via a facile liquid-liquid diffusion-assisted crystallization approach.The encapsulation mechanism is then analyzed.Depending on the ratios of blue/yellow emitters,these luminescent composites exhibit white light emission with tunable cold and warm hues.The composites also possess prominent ultraviolet resistance,thermal tolerance,and good stability at about 200°C.By employing such“CDs in metal halide”composites as a converter,a WLED is successfully fabricated with a high color rendering index of 93.6,benefiting from the assembled blue and yellow broadband emission.With this strategy,the developed composites show great promise in next-generation WLED lighting.
基金supported by the National Key R&D Program of China(Grant No.2016YFA0300404)the National Key Projects for Basic Research in China(Grant No.2015CB921202)+4 种基金the National Natural Science Foundation of China(Grant Nos.11574133,and 51372112)the Natural Science Foundation Jiangsu Province(Grant No.BK20150012)the Science Challenge Project(Grant No.TZ2016001)the Fundamental Research Funds for the Central UniversitiesSpecial Program for Applied Research on Super Computation of the National Natural Science FoundationGuangdong Joint Fund
文摘In this study, we used the crystal structure search method and first-principles calculations to systematically explore the highpressure phase diagrams of the TaAs family （NbP, NbAs, TaP, and TaAs）. Our calculation results show that NbAs and TaAs have similar phase diagrams, the same structural phase transition sequence I41md→Pδm2→}P21/c→Pm3m, and slightly different transition pressures. The phase transition sequence of NbP and TaP differs somewhat from that of NbAs and TaAs, in which new structures emerge, such as the Cmcm structure in NbP and the Pmmn structure in TaP. Interestingly, we found that in the electronic structure of the high-pressure phase Pδm2-NbAs, there are coexisting Weyl points and triple degenerate points, similar to those found in high-pressure Pδm2-TaAs.
文摘In this paper the theoretical model is built for ZEpHyR(ZARM Experimental Hybrid Rocket) main engine which is being developed at ZARM institute,Bremen,Germany.The theoretical model is used to estimate the temperature of exhaust gas.The Conjugate Gradient Method(CGM) with Adjoint Problem for Function Estimation iterative technique is used to solve the Inverse Heat Conduction Problem(IHCP) to estimate the heat flux and internal wall temperature at the throat section of the nozzle.Bartz equation is used to calculate the convective heat transfer coefficient.The exhaust gas temperature is determined using the estimated heat flux,the wall temperature at internal surface of nozzle and the heat transfer coefficient.The accuracy of CGM iterative scheme to solve the IHCP is also investigated and its results are presented.
