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Abstract:With p-nitrophenol (PNP) as the target pollutant, the degradation characteristics of PNP by Rhodobacter sphaeroides H strain were studied. The degradation conditions were optimized by single factor test and response surface analysis, and the degradation ability of H strain to PNP was improved. Different reaction systems have been set up to prove that H strain living cells are the main body of degrading PNP, and can degrade PNP under anaerobic light, anaerobic darkness, aerobic light and aerobic darkness. The single factor experiments show that the significant influencing factors are initial concentration of PNP, pH value and temperature. The optimal degradation conditions after response surface optimization are: initial concentration of PNP is 81.01 mg·L^-1, pH value is 8.09 and temperature is 30.49 ℃. The predicted value of PNP degradation rate is 92.3%, which is 1.2%(<2%) different from the actual value(91.1%). Under the optimum conditions, the relationship between the growth of H strain and the concentration of PNP with time shows that the concentration of PNP decreased from 81.01 mg·L^-1 to 20.33 mg·L^-1 within 96 hours of the growth adaptation period of H strain, and the corresponding degradation rate is 74.9%. Then, in the exponential growth period of 96-168 hours, PNP is rapidly degraded, and the degradation rate reaches 91.1%. At the same time, the first-order kinetic equation of PNP degradation of H strain under this condition was fitted.

Abstract:To further study the biotransformation process and producing enzyme properties of bacterial strain of Rhodobacter sphaeroides to HMX, the effects of different carbon sources, nitrogen sources and metal ions on the biotransformation efficiency of HMX of the strain and its growth were studied. The intermediate metabolites of HMX degraded by Rhodobacter sphaeroides were analyzed by liquid chromatography-mass spectrometry (LC-MS), and the possible degradation pathways were presumed. The effects of different conditions on the specific activity of the enzymes produced by the strain were determined. The zymograms were analyzed by polyacrylamide gel electrophoresis. The results show that the optimum carbon source, combined nitrogen source and metal ion for transforming HMX by the strain are malic acid, (NH₄)₂SO₄ and yeast extract, Ca²⁺, respectively. When the initial concentration of HMX is 100 mg·L^-1, after 96 h of culture, three substances can be detected: two HMX nitroso derivatives (mononitroso mNs-HMX and dinitroso dNs-HMX), methine dinitramine (MEDINA), and the mass-to-charge ratios of their mother ions are 279, 263 and 136, respectively. The possible degradation pathways presumed have two branches. One branche is that HMX is reduced to mNs-HMX and dNs-HMX by reductase, the other branche is that HMX is transformed and open-loop cleavaged into methine dinitramine by hydrolase. The specific activity of enzyme and polyacrylamide gel electrophoresis experiments show that the specific activity of the enzyme produced by the strain is significantly promoted when the concentration of HMX is 75 mg·L^-1 and 100 mg·L^-1, while when the concentration of HMX is 125 and 50 mg·L^-1, the specific activity of the enzyme produced by the strain has an inhibitory effect. When pH is 7, the specific activity of the enzyme produced by the strain is the highest.

Abstract:Typical military explosives, such as trinitrotoluene（TNT）, hexogen, octogen, pentaerythritol tetranitrate, can cause a variety of toxic effects on mammalian tissues and organs such as liver, kidney, blood and nerves. This paper reviewed the toxic effects and mechanisms of typical explosives, and briefly summarized their cellular, microbial and animal toxic effects, as well as the epidemiological statistics of occupational populations. Taking TNT as an example, the review also introduced the toxic mechanisms of typical explosive, emphasizing the oxidative stress and the reaction of TNT metabolites with protein and DNA. Finally, it was pointed out that the current toxicity study of explosives mainly focuses on the testing of toxicity, while the understanding on toxic mechanisms of explosives is lacking. We presented future research priorities. For example, the quantitative structure-activity relationship between explosive molecules and biological toxicity by the machine learning technology, the investigation of toxic mechanism for nitroaromatic explosives, including hemoglobinemia, toxic cataract, carcinogenic and teratogenic, should be paid more attention.

Abstract:Energetic compounds represented by trinitrotoluene (TNT), cyclotrimethylene trinitramine (RDX) and cyclotetramethylene tetranitramine (HMX) are highly toxic. When released into the environment, these energetic compounds will undergo complex redistribution, migration and transformation in soil-water-organism system, and pose hazards to ecosystems and human health. According to the pollution status of energetic compounds in domestic and foreign sites, the environmental behaviors of TNT, RDX and HMX in soil such as dissolution/precipitation, volatilization, adsorption/desorption, photolysis, hydrolysis, reduction, microbial degradation and plant uptake and transformation were reviewed. The physical and chemical properties of explosives and soils, and the effect of on-site environmental conditions on these complex environmental behaviors were also analyzed. The latest research on the environmental behavior of hexanitrohexaazaisowurtzitane (CL-20) and other novel explosives was briefly introduced. Based on the current research status, it is recommended that more attention should be paid to marine environmental ammunition pollution and combined pollution between energetic compounds and heavy metals in the future, and more attention should be paid to the application of the advanced technologies, such as compound-specific stable isotope analysis, to the environmental behavior and fate of explosives.

Abstract:To improve the safety performance of hexanitrohexaazaisowurtzitane (CL-20) and maintain its higher energy, three kinds of CL-20/FOX-7 polymer bonded explosives(PBXs) with different formulation proportions were prepared by water suspension coating method using polyurethane polymer Estane as coating agent and 1,1-diamino-2,2-dinitroethene(FOX-7) as energetic sensitivity-reducing component. The morphology structure, crystal form, thermal decomposition characteristic and impact and friction sensitivity of samples were tested and analyzed by scanning electron microscopy (SEM), X-ray diffractometer (XRD), differential scanning calorimeter (DSC), impact sensitivity tester and friction sensitivity tester. The detonation velocity of three kinds of PBXs was tested by an electrical measurement method. The results show that the explosive particles based on CL-20/FOX-7 have better coating effect, and neither CL-20 nor FOX-7 has crystal transformation. The apparent activation energy of three kinds of PBXs are increased by 17.12, 32.87 and 40.24 kJ·mol^-1 compared with refined CL-20. The enthalpies of activation (ΔH) of PBX samples are also significantly improved compared with CL-20. The characteristic drop height increases from 27.5 cm of refine CL-20 to 58.3, 56.5 cm and 54.2 cm， respectively, compared with CL-20. The actual detonation velocities of three kinds of PBXs with different formulation proportions are 8474, 8503 m·s^-1 and 8577 m·s^-1 ，respectively, which is equivalent to the detonation velocity of PBXN-5, but the characteristic drop height increases by more than 48.5% compared with PBXN-5, the safety performance of explosives is significantly improved.

Abstract:Using 3-azido-4-aminofurazan (AAF) as starting material, 3-azido-3′-nitrodifurazanyl ether (ANFO) was designed and synthesized for the first time via Caro′s acid oxidation, hydrolysis and intermolecular etherification sequence with a total yield of 32.7%, and the structures of ANFO and intermediates were characterized by ¹H NMR, ¹³C NMR, FT-IR, MS and elementary analysis. The oxidation method for 3-azido-4-nitrofurazan（ANF） was improved from hydrogen peroxide (50%), sulfuric acid and sodium tungstate as new oxidation system with a yield of 75.1%. The optimal conditions of oxidation and etherification were discussed, and the best conditions were obtained as follows: n(H₂O₂)∶n(H₂SO₄) is 1∶1.5 for oxidation system. The reaction temperature is at 30 ℃ for etherification system. The structure of ANFO was optimized by B3LYP/6-31G(d, p) method，the thermodynamic properties of ANFO at different temperatures were calculated on the basis of vibration analysis. The physicochemical properties and detonation performances of ANFO were studied by DSC measurement and the density functional theory (DFT) method. The calculated density, melting point, detonation velocity, detonation pressure, impact sensitivity(H₅₀) and heat of detonation are 1.85 g·cm^-3, 182.3 ℃(dec.), 8660 m·s^-1, 33.81 GPa, 35.2 cm and 6725 kJ·kg^-1, respectively.

Abstract:Tri-functional random copolyether of NIMMO and THF(tri-functionality NIMMO-THF copolyether) energetic binder was synthesized by the ring opening polymerization of NIMMO(3-nitratomethyl-3-methyloxetane) and THF(tetrahydrofuran) using trimethylolpropane(TMP) as initiator,boron trifluoride ether complex BF₃·OEt₂ ascatalyst. The products were characterized by infrared spectroscopy, nuclear magnetic resonance and differential scanning calorimetry(DSC). Taking tri-functionality NIMMO-THF copolyether energetic binder curried and synthesized by hexamethylenediisocynate (HDI) as curing agent, a series of elastomers were prepared according to the molar ratio of ─NCO of hexamethylenediisocynate (HDI) to ─OH of tri-functionality NIMMO-THF (R value) as R=0.8, 0.9, 1.0, 1.1, 1.2 respectively. The mechanical properties and thermal properties of elastomers were investigated. The results show that the temperature of exothermic peak of the tri-functionality NIMMO-THF copolyether energetic binder obtained by DSC at 10 ℃·min^-1 is 216 ℃. When R value is 1.1, the tensile strength of the elastomer is the highest, which is 1.32 MPa and the temperature of exothermic peak of the elastomer obtained by DSC at 10 ℃·min^-1 is 203 ℃.

Abstract:3-(5′-Amino-3′-diazenyl-1′,2′,4′-oxadiazol)-5-one-1,2,4-oxadiazol (BAKIF) and 3,3′-azo-1,2,4-oxadiazol-5,5′-dione (BDKIF) were synthesized respectively via three step reactions of cyclization, coupling and nitrification using sodium dicyanamide as raw material. The single crystals of BAKIF and BDKIF were obtained by solvent evaporation method from methanol. Their crystal structures were characterized by X-ray single-crystal diffraction technique. Their thermal stabilities were studied by DSC-TG. Their detonation performances were predicted by EXPLO5. The results show that the crystal density of BAKIF·2H₂O molecule is 1.645 g·cm^-3 at 173 K. The crystal belongs to orthorhombic system, space group P2₁2₁2₁ with cell parameters of a=4.6661(4) Å, b=13.5836(10) Å, c=14.8537(10) Å, V=941.46(12) ų, Z=4， μ=0.149 mm^-1, F(000)＝480. The crystal density of BDKIF molecule is 1.708 g·cm^-3 at 173 K. The crystal belongs to trigonal system, space group R-3 with cell parameters of a=20.4183(12) Å, b=20.4183(12) Å， c=4.8017(7) Å, V=1733.7(3) ų, Z=9, μ=0.153 mm^-1, F(000)＝900. The exothermic peak temperature of BAKIF and BDKIF at 5 ℃·min^-1 is 290.01 ℃ and 149.75 ℃, respectively. Theoretical detonation velocity and theoretical detonation pressure are 7292 m·s^-1 and 21.5 GPa for BAKIF, and 7363 m·s^-1 and 20.7 GPa for BDKIF, which are superior to those of TNT. Considering that they are potential insensitive energetic materials.

Abstract:To improve the surfaceoxidation of aluminum powder, and the catalytic effect on thethermal decomposition of energy materials, using electric explosive aluminum powder and copper chloride dihydrate（CuCl₂·2H₂O）as raw materials, the rapid deposition of nano-copper particles on the surface of aluminum powder was realized and the uniform coated Cu/Al composite was prepared by displacement method, in which nano-sized copper particles was made to cover the surface of aluminum powder.The structure and morphology of the composite were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray powder diffraction(XRD), energy dispersive spectroscopy(EDS),etc. DSC curves of the mixture of Cu/Al composite and RDX (mass ratio as 1∶5) at different heating rates were measured. The kinetic parameters of the thermal decomposition reaction of the mixture were calculated. Results show that the oxide layer on the surface of electric explosive aluminum powder is stripped by the etching of ammonium fluoride. The composite material contains simple substance aluminum and simple substancecopper crystallinephase, but no copper oxide and aluminacrystalline phases. Nano-sized copper particles are uniformly coated on the surface of aluminum powder andthe particle diameterof the composite is 200-500 nm. After the addition of Cu/Al composite,the initial decomposition temperature and peak temperature of RDX decrease by 8.51 ℃ and 26.43 ℃ respectively, the heat of decomposition increases by 296 J·g^-1, and the activation energy of thermal decomposition decreases by 19.19 kJ·mol^-1, indicating that Cu/Al composite can promote the thermal decomposition behaviorof RDX．

Abstract:The boron based fuel-rich propellant is considered as one of the ideal fuel for solid rocket ramjet owning to the high gravimetric and volumetric heating value of boron. However, the amorphous boron powder could react with the terminal hydroxyl groups of the binder, causing increase of apparent viscosity and pot-life of the slurry shortening. The theoretical volumetric heating values of three boron-based propellants were calculated, in which hydroxyl-terminated polybutadiene (HTPB), 3,3-bis (azidomethyl) oxetane and tetrahydrofuran copolyether (PBT) and gycidyl azide polymer (GAP) was used as the binder. The rheological properties and infrared characteristics of B/HTPB, B/PBT and B/GAP at high shear rate were studied by the co-rotating twin screw rheometer and Fourier transform infrared spectrometer, respectively. The reactivity of terminal hydroxyl groups for the three binders was analyzed. At a rational designed composition of 50∶20∶30, the volumetric heating values exceeded 64.00 MJ·dm^-3 for B/PBT/AP and B/GAP/AP, which was higher than B/HTPB/AP system (61.08 MJ·dm^-3). At shear rate of 355.56 s^-1 and 55 ℃, the apparent viscosity for B/HTPB slurry with 25% boron rapidly increased to 260Pa·s and reached gel state after 110 min mixing. After 7 h under same condition, the apparent viscosity increased from 3.63 Pa·s to 10.6 Pa·s for B/PBT with 40% boron, whereas reduced from 5.96 Pa·s to 0.33 Pa·s for B/GAP with 55% boron. For B/HTPB slurry, enhanced B—O vibration absorption and gradually weaken C—O vibration absorption were detected during mixing, which were unchanged for B/PBT and B/GAP slurries. Therefore, considering reacting with the acidic impurities on the surface of boron particles, the reactivity of terminal hydroxyl groups of PBT and GAP were much lower than that of HTPB, which would facilitate processing of boron-based propellant.

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