Preliminary discussion on the ignition mechanism of exploding foil initiators igniting boron potassium nitrate

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.

Crystallization Kinetics of Batch Spontaneous Nucleation of Potassium Nitrate

The batch cooling crystallization initiated from spontaneous nucleation for aqueous solution of potassium nitrate was studied. The concentration and transmittance data were acquired on line throughout the operation.Based on solute mass transfer in both liquid and solid phases, a kinetic model was deduced by assuming that the late period of primary nucleation resembles the initial period of the secondary nucleation. Nucleation and crystal growth stages were identified. Kinetic parameters were estimated piecewise from online experimental data and compared with those in literature. The estimated kinetic parameters for stages without apparent primary nucleation agreed well with those in literature. Further, a simulated concentration curve was also drawn from the estimated kinetic parameters and it matched well with that in experiment.

Packaging category and its influencing factors of potassium nitrate

To understand the combustion characteristics of potassium nitrate and evaluate the magnitude of combustion risk, ox-idation solid test apparatus is used and the updated experimental criterion of the United Nations is adopted to measure the pack-aging category of potassium nitrate. The new criterion puts calcium peroxide and microcrystalline cellulose as references and burning rate as evaluation index. Effects of mixing ratio and insert medium on burning rate are reached. Test results show that pure potassium nitrate doesn＇t burn under normal temperature and pressure, however, its oxidation is very strong and the packaging category should choose the class I. As the mass fraction of potassium nitrate reduces, the burning rate first increases and then decreases. When the ratio is 2 ： 1,the combustion rate reaches the maximum, and the effect of combustion is the best. When 1 ： 3, the combustion rate is the minimum. The mixture combustion can be suppressed by silicon dioxide and hy-drogen phosphate, which is not fired when silica concentration is 40% or ammonium hydrogen potassium phosphate is 55%, their effects are very obvious.

New solid superbases: potassium nitrate supported on porous materials

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-Al2O3, etc. are extremely sensitive to CO2 or H2O in the atmosphere, which limits their application in industrial scale. In or-

Effect of interface carbonization on dielectric properties of potassium nitrate nanocomposite based on porous glasses

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.

Amelioration of Salt Stress in Sugarcane (Saccharum officinarum L.) by Supplying Potassium and Silicon in Hydroponics

A hydroponics experiment was conducted to evaluate the role of potassium (K) and silicon (Si) in mitigating the deleterious effects of NaCl on sugarcane genotypes differing in salt tolerance.Two salt-sensitive (CPF 243 and SPF 213) and two salt-tolerant (HSF 240 and CP 77-400) sugarcane genotypes were grown for six weeks in 1/2 strength Johnson's nutrient solution.The nutrient solution was salinized by two NaCl levels (0 and 100 mmol L 1 NaCl) and supplied with two levels of K (0 and 3 mmol L 1) and Si (0 and 2 mmol L 1).Applied NaCl enhanced Na + concentration in plant tissues and significantly (P ≤ 0.05) reduced shoot and root dry matter in four sugarcane genotypes.However,the magnitude of reduction was much greater in salt-sensitive genotypes than salt-tolerant genotypes.The salts interfered with the absorption of K + and Ca 2+ and significantly (P ≤ 0.05) decreased their uptake in sugarcane genotypes.Addition of K and Si either alone or in combination significantly (P ≤ 0.05) inhibited the uptake and transport of Na + from roots to shoots and improved dry matter yields under NaCl conditions.Potassium uptake,K + /Na + ratios,and Ca 2+ and Si uptake were also significantly (P ≤ 0.05) increased by the addition of K and/or Si to the root medium.In this study,K and Si-enhanced salt tolerance in sugarcane genotypes was ascribed to decreased Na + concentration and increased K + with a resultant improvement in K + /Na + ratio,which is a good indicator to assess plant tolerance to salt stress.However,further verification of these results is warranted under field conditions.

The effects of different nitrogen sources on camptothecin content and related gene expression in Camptotheca acuminata seedlings

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.

Isolation,characterization and identification of plant growth-promoting rhizobacteria from the rhizosphere of Acacia mangium at sandy BRIS soil

This study has isolated,characterized,and identified potential plant growthpromoting rhizobacteria(PGPR)with multiple PGP characteristics(N_(2)-fixation,P-and K-solubilization,IAA,and siderophores production)from the rhizosphere BRIS soil of Acacia mangium.A total of 24 pure colonies were isolated and only 8 colonies were selected for further evaluation of the growth rate in 5%organic molasses medium supplemented with 2%KNO_(3).Based on the biochemical,potential PGP characteristics and growth performance,3 superior PGPR strains were selected and identified as Paraburkholderia unamae(UA1),Bacillus amyloliquefaciens(UA6),and Enterobacter asburiae(UAA2)by partial sequencing of the 16S rRNA gene.The selected bacterial strains either in single or mixed(UA1+UA6+UAA2)cultures have shown a significant biochemical estimation of the PGP characteristics.Each strain has its own PGPR traits superiority with UA1 showing the best PGP characteristic followed by UA6 and UAA2.The use of mixed bacterial strains was beneficial as it showed the best performance in N_(2)-fixation,siderophores production,and significant effect on corn phenology,growth and yield compared to using a single strain.These types of microbes showed potential to be used as biofertilizer and should be exploited more.

Preparation and Characterization of KNO3/Diatomite Shape-Stabilized Composite Phase Change Material for High Temperature Thermal Energy Storage

A new potassium nitrate （KNO3）]diatomite shape-stabilized composite phase change material （SS- CPCM） was prepared by the mixing and sintering method. KNO3 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 KNO3 could be retained 65 wt% into pores and on surfaces of diatomite without the leakage of melted KNO3 from the SS-CPCM. The calculated filling rate of molten KNO3 that could enter into the disc-like shape pore of diatomite verified the scanning elec- tronic microscopy images of SS-CPCM. X-ray diffraction and Fourier transform infrared spectroscopy results showed that no reaction occurred between KNO3 and diatomite, performing good compatibility. Accord- ing to the differential scanning calorimetry results, after 50 thermal cycles, the phase change temperatures for melting and freezing of SS-CPCM with 65 wt% KNO3 were changed from 330.23 ℃ and 332.90 ℃ to 330.11 ℃ and 332.84 ℃ 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 KNO3/diatomite SS-CPCM may be considered as a potential storage media in solar power plants for thermal energy storage.