Exploding foil initiator(EFI)is a kind of advanced device for initiating explosives,but its function is unstable when it comes to directly igniting pyrotechnics.To solve the problem,this research aims to reveal the ig...Exploding foil initiator(EFI)is a kind of advanced device for initiating explosives,but its function is unstable when it comes to directly igniting pyrotechnics.To solve the problem,this research aims to reveal the ignition mechanism of EFIs directly igniting pyrotechnics.An oscilloscope,a photon Doppler velocimetry,and a plasma spectrum measurement system were employed to obtain information of electric characteristics,impact pressure,and plasma temperature.The results of the electric characteristics and the impact pressure were inconsistent with ignition results.The only thing that the ignition success tests had in common was that their plasma all had a relatively long period of high-temperature duration(HTD).It eventually concludes that the ignition mechanism in this research is the microconvection heat transfer rather than the shock initiation,which differs from that of exploding foil initiators detonating explosives.Furthermore,the methods for evaluating the ignition success of semiconductor bridge initiators are not entirely applicable to the tests mentioned in this paper.The HTD is the critical parameter for judging the ignition success,and it is influenced by two factors:the late time discharge and the energy of the electric explosion.The longer time of the late time discharge and the more energy of the electric explosion,the easier it is to expand the HTD,which improves the probability of the ignition success.展开更多
ACCORDING to Tanabe’s definition, all materials possessing the basic strength （H-） over 26.5 are superbases. However, most of superbases known up to now, including CaO and SrO evacuated at 1173 K, K or Na metal sup...ACCORDING to Tanabe’s definition, all materials possessing the basic strength （H-） over 26.5 are superbases. However, most of superbases known up to now, including CaO and SrO evacuated at 1173 K, K or Na metal supported on KOH/γ-Al<sub>2</sub>O<sub>3</sub>, etc. are extremely sensitive to CO<sub>2</sub> or H<sub>2</sub>O in the atmosphere, which limits their application in industrial scale. In or-展开更多
Dielectric properties and structure of pure and carbon-modified nanocomposites on the base of porous glasses with an average pore diameter of 6 nm(PG6)with embedded KNO3 have been studied at the temperature diapason o...Dielectric properties and structure of pure and carbon-modified nanocomposites on the base of porous glasses with an average pore diameter of 6 nm(PG6)with embedded KNO3 have been studied at the temperature diapason of 300-430 K and at fre-quencies of 0.1-3×10^(6) Hz on cooling.X-ray diffraction studies of these samples have shown,that in modified and unmodified composites there is a mixture of the low-temperature paraelectric phase(α-phase)and the ferroelectricγ-phase.In modified composites,a decrease in permittivity and conductivity is observed.Dielectric response has been analyzed in the framework of modern theoretical models.Two relaxation processes have been identified and their origin has been determined.It has been found that the main contribution to the dielectric response of nanocomposite material PG6+KNO3 is provided by charge polarization on interfaces,which can be governed by modifying the inner pore surfaces.DC-conductivity of both composites has been estimated and the activation energies have been determined.Activation energy change observed in a vicinity of 360 K is attributed to the phase transformation and the appearance of KNO3α-phase.展开更多
Camptotheac acuminata Decne is a unique tree species in China with an important secondary metabolite,camptothecin(CPT),used in the treatment of cancer.Nitrogen(N)is an important element that affects plant growth and t...Camptotheac acuminata Decne is a unique tree species in China with an important secondary metabolite,camptothecin(CPT),used in the treatment of cancer.Nitrogen(N)is an important element that affects plant growth and the accumulation of CPT.Reports on the effect of N on CPT synthesis from a genetic perspective are scarce.To explore the effects of different N sources and levels on CPT synthesis in C.acuminata,two-year-old seedlings were fertilized with different concentrations of pure ammonium sulphate,source of ammonium N(NH4+-N),and potassium nitrate for nitrate N(NO3--N).Concentrations of 2.5,5,7.5,and10 g pot-1 NH4+-N and NO3--N were used.The results showed that 7.5 g NH4+-N and NO3--N treatments were best for growth and fresh weight of leaves.Compared with the other treatments,the CPT content,tryptophan synthase and tryptophan decarboxylase activities,and expression of the CaTSB and CaTDCl genes under the 2.5 g NH4+-N and NO3--N treatments peaked significantly at 30 days.However,the expression of CaTDC2 surpassed that of the other two genes at 60 days.Therefore,compared with NH4+-N source,the NO3--N source was more beneficial for growth,and NO3--N was better for CPT yield.Consequently,leaves of C.acuminata treated with 2.5 g NO3--N could be harvested after 30 days to obtain maximum CPT content.CaTDC1 is more closely linked to CPT synthesis.The results of this study improved the production of CPT in C.acuminata via fertilization.展开更多
A new potassium nitrate(KNO_3)/diatomite shape-stabilized composite phase change material(SSCPCM) was prepared by the mixing and sintering method. KNO_3 served as the phase change material(PCM) for thermal energy stor...A new potassium nitrate(KNO_3)/diatomite shape-stabilized composite phase change material(SSCPCM) was prepared by the mixing and sintering method. KNO_3 served as the phase change material(PCM) for thermal energy storage, while diatomite acted as the carrier matrix to provide the structural strength and prevent the leakage of PCM. It was found that KNO_3 could be retained 65 wt% into pores and on surfaces of diatomite without the leakage of melted KNO_3 from the SS-CPCM. The calculated filling rate of molten KNO_3 that could enter into the disc-like shape pore of diatomite verified the scanning electronic microscopy images of SS-CPCM. X-ray diffraction and Fourier transform infrared spectroscopy results showed that no reaction occurred between KNO_3 and diatomite, performing good compatibility. According to the differential scanning calorimetry results, after 50 thermal cycles, the phase change temperatures for melting and freezing of SS-CPCM with 65 wt% KNO_3 were changed from 330.23 °C and 332.90 °C to330.11 °C and 332.84 °C and corresponding latent heats varied from 60.52 J/g and 47.30 J/g to 54.64 J/g and 41.25 J/g, respectively. The KNO_3/diatomite SS-CPCM may be considered as a potential storage media in solar power plants for thermal energy storage.展开更多
文摘Exploding foil initiator(EFI)is a kind of advanced device for initiating explosives,but its function is unstable when it comes to directly igniting pyrotechnics.To solve the problem,this research aims to reveal the ignition mechanism of EFIs directly igniting pyrotechnics.An oscilloscope,a photon Doppler velocimetry,and a plasma spectrum measurement system were employed to obtain information of electric characteristics,impact pressure,and plasma temperature.The results of the electric characteristics and the impact pressure were inconsistent with ignition results.The only thing that the ignition success tests had in common was that their plasma all had a relatively long period of high-temperature duration(HTD).It eventually concludes that the ignition mechanism in this research is the microconvection heat transfer rather than the shock initiation,which differs from that of exploding foil initiators detonating explosives.Furthermore,the methods for evaluating the ignition success of semiconductor bridge initiators are not entirely applicable to the tests mentioned in this paper.The HTD is the critical parameter for judging the ignition success,and it is influenced by two factors:the late time discharge and the energy of the electric explosion.The longer time of the late time discharge and the more energy of the electric explosion,the easier it is to expand the HTD,which improves the probability of the ignition success.
文摘ACCORDING to Tanabe’s definition, all materials possessing the basic strength （H-） over 26.5 are superbases. However, most of superbases known up to now, including CaO and SrO evacuated at 1173 K, K or Na metal supported on KOH/γ-Al<sub>2</sub>O<sub>3</sub>, etc. are extremely sensitive to CO<sub>2</sub> or H<sub>2</sub>O in the atmosphere, which limits their application in industrial scale. In or-
基金The reported study was funded by RFBR,DST(India)and NRF(South Africa)according to the research project№19-52-80019 BRICS_t.
文摘Dielectric properties and structure of pure and carbon-modified nanocomposites on the base of porous glasses with an average pore diameter of 6 nm(PG6)with embedded KNO3 have been studied at the temperature diapason of 300-430 K and at fre-quencies of 0.1-3×10^(6) Hz on cooling.X-ray diffraction studies of these samples have shown,that in modified and unmodified composites there is a mixture of the low-temperature paraelectric phase(α-phase)and the ferroelectricγ-phase.In modified composites,a decrease in permittivity and conductivity is observed.Dielectric response has been analyzed in the framework of modern theoretical models.Two relaxation processes have been identified and their origin has been determined.It has been found that the main contribution to the dielectric response of nanocomposite material PG6+KNO3 is provided by charge polarization on interfaces,which can be governed by modifying the inner pore surfaces.DC-conductivity of both composites has been estimated and the activation energies have been determined.Activation energy change observed in a vicinity of 360 K is attributed to the phase transformation and the appearance of KNO3α-phase.
基金This research was sponsored by the 13th Five-Year-Plan National Projects for Camptotheca acuminata Decne Effi cient Cultivation Technology Research of China(2017YFD0600706).
文摘Camptotheac acuminata Decne is a unique tree species in China with an important secondary metabolite,camptothecin(CPT),used in the treatment of cancer.Nitrogen(N)is an important element that affects plant growth and the accumulation of CPT.Reports on the effect of N on CPT synthesis from a genetic perspective are scarce.To explore the effects of different N sources and levels on CPT synthesis in C.acuminata,two-year-old seedlings were fertilized with different concentrations of pure ammonium sulphate,source of ammonium N(NH4+-N),and potassium nitrate for nitrate N(NO3--N).Concentrations of 2.5,5,7.5,and10 g pot-1 NH4+-N and NO3--N were used.The results showed that 7.5 g NH4+-N and NO3--N treatments were best for growth and fresh weight of leaves.Compared with the other treatments,the CPT content,tryptophan synthase and tryptophan decarboxylase activities,and expression of the CaTSB and CaTDCl genes under the 2.5 g NH4+-N and NO3--N treatments peaked significantly at 30 days.However,the expression of CaTDC2 surpassed that of the other two genes at 60 days.Therefore,compared with NH4+-N source,the NO3--N source was more beneficial for growth,and NO3--N was better for CPT yield.Consequently,leaves of C.acuminata treated with 2.5 g NO3--N could be harvested after 30 days to obtain maximum CPT content.CaTDC1 is more closely linked to CPT synthesis.The results of this study improved the production of CPT in C.acuminata via fertilization.
基金supported by the Program for New Century Excellent Talents in University (Grant No. NCET-08-828)the Program for the China Geological Survey (No. 1212011120323)the Fundamental Research Funds for the Central Universities (No. 2011YXL003)
文摘A new potassium nitrate(KNO_3)/diatomite shape-stabilized composite phase change material(SSCPCM) was prepared by the mixing and sintering method. KNO_3 served as the phase change material(PCM) for thermal energy storage, while diatomite acted as the carrier matrix to provide the structural strength and prevent the leakage of PCM. It was found that KNO_3 could be retained 65 wt% into pores and on surfaces of diatomite without the leakage of melted KNO_3 from the SS-CPCM. The calculated filling rate of molten KNO_3 that could enter into the disc-like shape pore of diatomite verified the scanning electronic microscopy images of SS-CPCM. X-ray diffraction and Fourier transform infrared spectroscopy results showed that no reaction occurred between KNO_3 and diatomite, performing good compatibility. According to the differential scanning calorimetry results, after 50 thermal cycles, the phase change temperatures for melting and freezing of SS-CPCM with 65 wt% KNO_3 were changed from 330.23 °C and 332.90 °C to330.11 °C and 332.84 °C and corresponding latent heats varied from 60.52 J/g and 47.30 J/g to 54.64 J/g and 41.25 J/g, respectively. The KNO_3/diatomite SS-CPCM may be considered as a potential storage media in solar power plants for thermal energy storage.
