The molecular simulations of the well-known high explosive β-HMX (cyclotetramethylene tetranitramine) anditsfluorine containing polymer-bonded explosives(PBXs) were carried out with the combination method of quantum ...The molecular simulations of the well-known high explosive β-HMX (cyclotetramethylene tetranitramine) anditsfluorine containing polymer-bonded explosives(PBXs) were carried out with the combination method of quantum mechanics, molecular mechanics and molecular dynamics. The atomic cluster model, containing the β-HMX molecule and the polymer molecule whose chain dimension was about the same as β-HMX’s, was fully optimized by AM1 and PM3 semi-empirical molecular orbital and molecular mechanical methods using COMPASS and PCFF force field. Then the calculated binding energy is found to be linearly correlated to each other. Molecular dynamics simulations using COM- PASS force field were performed for β-HMX crystal and the PBXs involving β-HMX and a series of fluorine containing polymers. Their elastic coefficients, moduli and Poisson’s ratios were calculated. It is found that the mechanical prop- erties of β-HMX can be effectively improved by blending with fluorine containing polymers in small amounts.展开更多
A one dimension solid and a two dimension solid consisting of polyoxoanions bridged by {CoO 3N 2} and {CoO 4} groups respectively have been synthesized by the hydrothermal method and structurally characterized by...A one dimension solid and a two dimension solid consisting of polyoxoanions bridged by {CoO 3N 2} and {CoO 4} groups respectively have been synthesized by the hydrothermal method and structurally characterized by X Ray crystallography. Each structure has the [(PO 4) 4Mo 6O 15 ] 12- cluster that is commonly observed in many molybdophosphates. In compound 1, [(PO 4) 4Mo 6O 15 ] 12- clusters are linked by {CoO 3N 2} groups to form a chain like structure, and the chains are hydrogen bonded into a network. Compound 2 is a layer structure with channnels constructed from [(PO 4) 4Mo 6O 15 ] 12- clusters and {CoO 4} groups, the organic molecules and the lattice water molecules are distributed disorderly in the interlamellar region and form strong hydrogen bonds with inorganic framework. The IR and the fluorescent spectra were investigated and discussed.展开更多
Two new ent-kauranoids, named maoyecrystals A (1) and B (2), were isolated from the EtOAc extract of the dried leaves of Isodon japonica (Burman f.) Hara collected in Tongbai mountains, Henan Province. Their structur...Two new ent-kauranoids, named maoyecrystals A (1) and B (2), were isolated from the EtOAc extract of the dried leaves of Isodon japonica (Burman f.) Hara collected in Tongbai mountains, Henan Province. Their structures were determined on the basis of spectral data, especially by 2D NMR.展开更多
This study of the thermal decomposition kinetics of various average diameter nano-particles of cal-cium carbonate by means of TG-DTA(thermogravimetry and differential thermal analysis) showed that the thermal decompos...This study of the thermal decomposition kinetics of various average diameter nano-particles of cal-cium carbonate by means of TG-DTA(thermogravimetry and differential thermal analysis) showed that the thermal decomposition kinetic mechanisms of the same crystal type of calcium carbonate samples do not vary with decreasing of their average diameters ; their pseudo-active energy Ea; and that the top-temperature of decom-position Tp decreases gently in the scope of micron-sized diameter, but decreases sharply when the average di-ameter decreases from micron region to nanometer region. The extraordinary properties of nano-particles were explored by comparing the varying regularity of the mechanisms and kinetic parameters of the solid-phase reac-tions as well as their structural characterization with the variation of average diameters of particles. These show that the aggregation, surface effect as well as internal aberrance and stress of the nano-particles are the main reason causing both Ea and Tp to decline sharply with the decrease of the average diameter of nano-particles.展开更多
Two new compounds containing triarylamine and benzoic hydrazide units, 4- [N,N-di(4-toyl)amino]benzaldehyde-N-(4-ethoxylphenyl)-formyl hydrazone 3a and 4-[N,N-di(4- toyl) amino]benzaldehyde-N-(2-ethoxylphenyl)-formyl ...Two new compounds containing triarylamine and benzoic hydrazide units, 4- [N,N-di(4-toyl)amino]benzaldehyde-N-(4-ethoxylphenyl)-formyl hydrazone 3a and 4-[N,N-di(4- toyl) amino]benzaldehyde-N-(2-ethoxylphenyl)-formyl hydrazone 3b, have been synthesized and their crystal structures (C30H29N3O2, Mr = 463.56) were interpreted by a combination technique of 1HNMR, IR, elemental analysis, mass spectra, UV-Vis spectra and X-ray crystallography, respec- tively. The crystal of 3a belongs to monoclinic, space group P21/n with a = 9.321(3) ? b = 11.046(4) ? c = 24.335(9) ? b =92.649(7), V = 2502.7(16) ?, Z = 4, m = 0.078 mm-1, Dc =1.230 g/cm3, F(000) = 984, the final R = 0.0590 and wR = 0.1316 for 4367 observed reflections with I > 2s(I). The crystal of 3b belongs to monoclinic, space group P21/c with a = 10.637(4) ? b = 24.138(10) ? c = 10.398(4) ? b = 104.913(8), V = 2579.8(17) ?, Z = 4, m = 0.075 mm-1, Dc = 1.194 g/cm3, F(000) = 984, the final R =0.0631 and wR =0.1006 for 4463 observed reflections with I > 2s(I). X-ray crystallography revealed that the nitrogen atom in the triarylamine moiety is of sp2 hybridization with the three phenyl rings twisted to each other.展开更多
The coastal seawater of Mediterranean of Alexandria receives large amount of discharged waters containing industrial wastes, sewage, and agricultural and domestic drainage. Fluoride and some parameters were(chemical a...The coastal seawater of Mediterranean of Alexandria receives large amount of discharged waters containing industrial wastes, sewage, and agricultural and domestic drainage. Fluoride and some parameters were(chemical and physical) determined. The data gave indication that the content and the amount of the discharged water largely affect the chemical composition of the coastal water. Stepwise regression analysis was highly significant and the model was very fruitful, where the observed and calculated values were mostly concordant. This may indicated that there was a relation between fluoride content in coastal seawater and its content in the discharged water.展开更多
The molecular structure of the title compound, ph3AsC (COCH3 )Seph, has been determined by X--ray diffraction. Crystallographic data: Mr= 517. 36'monoclinic, P21,/c, a=11. 499(4), b=9. 619(4), c=20. 919(7),A, β=9...The molecular structure of the title compound, ph3AsC (COCH3 )Seph, has been determined by X--ray diffraction. Crystallographic data: Mr= 517. 36'monoclinic, P21,/c, a=11. 499(4), b=9. 619(4), c=20. 919(7),A, β=98. 82(2)°,V= 2286(l) A 3, Z=4, Dc= 1. 509 g/cm3, μ(MoKa) = 3. 073 cm-1, F(000) = 1040and the final R=0. 042, Rw= 0. 041. In the molecule, the geometry of arsenic atom isa distorted tetrahedron, the bonds of Se--C (3) and As--C(31 ) have striking characteristics of double bond, the delocalization of electronic density occurs to be restrictedfrom O(1 ) to Se atoms.展开更多
A new process of enriching germanium from coal ash was developed. The processinvolves in mixing the coal ash and ammonium chloride and then roasting the mixture to producegermanium chloride that is then absorbed by di...A new process of enriching germanium from coal ash was developed. The processinvolves in mixing the coal ash and ammonium chloride and then roasting the mixture to producegermanium chloride that is then absorbed by dilute hydrochloric acid and hydrolyzed to germaniumoxide. The germanium recovery reached to 80.2% at the optimum condition: mass ratio of NH_4Cl/coalash is 0.15, roasting temperature 400℃ and roasting time 90 min.展开更多
The title complex, C15S2Cl2H16Pd, Mr = 437. 73, crystallizes in monoclinic space group P21/c with a = 10. 177(2), b=10. 788(1), c= 15. 305(1) (?),β=102. 73(1)°, V = 1638. 1(?)3, Z = 4, Dx =1.77g/cm3, μ = 16.8cm...The title complex, C15S2Cl2H16Pd, Mr = 437. 73, crystallizes in monoclinic space group P21/c with a = 10. 177(2), b=10. 788(1), c= 15. 305(1) (?),β=102. 73(1)°, V = 1638. 1(?)3, Z = 4, Dx =1.77g/cm3, μ = 16.8cm-1, F (000) = 872. The final structure refinement converged with unweighted and weighted R factors of 0. 025 and 0. 033 for 2490 observed unique reflections. The complex has mononuclear structure with the ligand cis-chelated to the Pd(Ⅱ) atom.展开更多
Regularity of the initial atmospheric corrosion of A3 steel in the presence of NaCI was investigated. The results showed that NaCI can accelerate the corrosion of A3 steel. Dry mass gain of A3 steel in the presence of...Regularity of the initial atmospheric corrosion of A3 steel in the presence of NaCI was investigated. The results showed that NaCI can accelerate the corrosion of A3 steel. Dry mass gain of A3 steel in the presence of NaCI deposition increases with the exposure time, which can be correlated by using exponential decay function. The relationship between dry mass gain and amount of NaCI deposition at a certain exposure time follows a quadratic function. More amount of NaCI deposition will slow down the corrosion rate to some extent after exposure for a certain time. SEM/EDAX was used to characterize the corrosion surface and products. The surfaces of the NaCI treated A3 steel were obviously uneven, and some tiny crevices appear in the corrosion products that could help O2 transmit to the inner layer. The amount of oxygen in atomic percentage in the corrosion products increases with the amount of NaCI deposition.展开更多
A capillary electrophoresis (CE) method has been firstly used for the separation of the therapeutically important xanthones from Securidaca inappendiculata. The separation of the nine xanthones was systematically opt...A capillary electrophoresis (CE) method has been firstly used for the separation of the therapeutically important xanthones from Securidaca inappendiculata. The separation of the nine xanthones was systematically optimized with respect to pH, concentration of running buffers, addition of sulfated b-CD, applied voltage and column temperature. Baseline separation was achieved for the nine xanthones in less than 15 minutes using a background electrolyte consisting of 200 mmol/L borate (pH 9.5) and 10 mmol/L sulfated b-CD.展开更多
The interaction between CH3OH and H2CO has been studied by ab ini-tio method at the level of STO-3G and 6-311G basis sets. It has been found that there are two possible complexes; a hydrogen bonded complex CH3OH...CH...The interaction between CH3OH and H2CO has been studied by ab ini-tio method at the level of STO-3G and 6-311G basis sets. It has been found that there are two possible complexes; a hydrogen bonded complex CH3OH...CH2O(Ⅰ) and an electron donor-acceptor complex CH3OH.....OCH2(Ⅱ).The stabilization energies of (Ⅰ) and (Ⅱ) are 14. 6 and 3. 6kJ/mol (STO-3G results) or 25. 1 and 17. 1kJ/mol (6-311G results) respectively. The nature of these complexes has been discussed by using the energy decomposition scheme.展开更多
The structure and proton conducting mechanism of solid polymer electrolyte (SPE) are described. Since the conductivity of electrolyte is important in SPE electrochemical cell research and development, we investigate q...The structure and proton conducting mechanism of solid polymer electrolyte (SPE) are described. Since the conductivity of electrolyte is important in SPE electrochemical cell research and development, we investigate quantitatively the conductivity of Nafion membrane and its dependence on temperature and relative humidity. Experimental results show that the conductivity of Nafion membrane increases with temperature and relative humidity. We also reports on the preparation and development of SPE membrane electrode with the emphasis on the mixture pressing method and impregnation-reduction process to prepare SPE composite electrode assemblies and their application to electrochemical sensors. We also investigate and fabricate a potentiometric electrochemical sensor of hydrogen and ethylene to measure the hydrogen and ethylene partial pressure.展开更多
Necessary and sufficient conditions for azeotropy in reactive mixtures are derived in terms of elemental composition, which shows that in the space of elemental compositions, they take the same functional form as the ...Necessary and sufficient conditions for azeotropy in reactive mixtures are derived in terms of elemental composition, which shows that in the space of elemental compositions, they take the same functional form as the conditions for azeotropy in non-reactive mixtures. The production of methyl tert-butyl ether (MTBE) is taken as an example. It is found that there are a 'pseudo' intermediate-boiling ternary reactive azeotrope at p = 101.325kPa and two 'real' ternary reactive azeotropes at p = 101.325 Pa. The introduced elemental compositions also reduce the dimensionality of the phase diagrams and provide a natural set of variables for visualization of phase behavior.展开更多
A new MEEKC method assisted with pressure-driven mobile phase was presented for the separation of felted explosives. Microemulsion solution was composed of 80 mmol/L heptane -120 mmol/L SDS (sodium dodecyl sulphate) -...A new MEEKC method assisted with pressure-driven mobile phase was presented for the separation of felted explosives. Microemulsion solution was composed of 80 mmol/L heptane -120 mmol/L SDS (sodium dodecyl sulphate) - 900 mmol/L butanol - 10 mmol/L borate at pH 9.4 and a pressure-driven flow of 0.020 mL/min under 1.3 MPa was employed to manipulate the separation. Explosives HMX (1, 3, 5, 7-tetranitro-l, 3, 5, 7-tetrazacyclooctane) and TATB (triamino-trinitrobenzene), which were felted on fluorine rubber F2311 (polytrifluorochlorethylene and polyvinylidene fluoride 1/1 co-polymerization) and F2314 (polytrifluorochlorethylene and polyvinylidene fluoride 4/1 co-polymerization) were well separated with very good peak shapes.展开更多
基金the National Natural Science Foundation of China(Grant Nos.10176012 and 20173028).
文摘The molecular simulations of the well-known high explosive β-HMX (cyclotetramethylene tetranitramine) anditsfluorine containing polymer-bonded explosives(PBXs) were carried out with the combination method of quantum mechanics, molecular mechanics and molecular dynamics. The atomic cluster model, containing the β-HMX molecule and the polymer molecule whose chain dimension was about the same as β-HMX’s, was fully optimized by AM1 and PM3 semi-empirical molecular orbital and molecular mechanical methods using COMPASS and PCFF force field. Then the calculated binding energy is found to be linearly correlated to each other. Molecular dynamics simulations using COM- PASS force field were performed for β-HMX crystal and the PBXs involving β-HMX and a series of fluorine containing polymers. Their elastic coefficients, moduli and Poisson’s ratios were calculated. It is found that the mechanical prop- erties of β-HMX can be effectively improved by blending with fluorine containing polymers in small amounts.
文摘A one dimension solid and a two dimension solid consisting of polyoxoanions bridged by {CoO 3N 2} and {CoO 4} groups respectively have been synthesized by the hydrothermal method and structurally characterized by X Ray crystallography. Each structure has the [(PO 4) 4Mo 6O 15 ] 12- cluster that is commonly observed in many molybdophosphates. In compound 1, [(PO 4) 4Mo 6O 15 ] 12- clusters are linked by {CoO 3N 2} groups to form a chain like structure, and the chains are hydrogen bonded into a network. Compound 2 is a layer structure with channnels constructed from [(PO 4) 4Mo 6O 15 ] 12- clusters and {CoO 4} groups, the organic molecules and the lattice water molecules are distributed disorderly in the interlamellar region and form strong hydrogen bonds with inorganic framework. The IR and the fluorescent spectra were investigated and discussed.
文摘Two new ent-kauranoids, named maoyecrystals A (1) and B (2), were isolated from the EtOAc extract of the dried leaves of Isodon japonica (Burman f.) Hara collected in Tongbai mountains, Henan Province. Their structures were determined on the basis of spectral data, especially by 2D NMR.
文摘This study of the thermal decomposition kinetics of various average diameter nano-particles of cal-cium carbonate by means of TG-DTA(thermogravimetry and differential thermal analysis) showed that the thermal decomposition kinetic mechanisms of the same crystal type of calcium carbonate samples do not vary with decreasing of their average diameters ; their pseudo-active energy Ea; and that the top-temperature of decom-position Tp decreases gently in the scope of micron-sized diameter, but decreases sharply when the average di-ameter decreases from micron region to nanometer region. The extraordinary properties of nano-particles were explored by comparing the varying regularity of the mechanisms and kinetic parameters of the solid-phase reac-tions as well as their structural characterization with the variation of average diameters of particles. These show that the aggregation, surface effect as well as internal aberrance and stress of the nano-particles are the main reason causing both Ea and Tp to decline sharply with the decrease of the average diameter of nano-particles.
基金This project was supported by the National Natural Science Foundation of China (No. 20072018 and 29832030)
文摘Two new compounds containing triarylamine and benzoic hydrazide units, 4- [N,N-di(4-toyl)amino]benzaldehyde-N-(4-ethoxylphenyl)-formyl hydrazone 3a and 4-[N,N-di(4- toyl) amino]benzaldehyde-N-(2-ethoxylphenyl)-formyl hydrazone 3b, have been synthesized and their crystal structures (C30H29N3O2, Mr = 463.56) were interpreted by a combination technique of 1HNMR, IR, elemental analysis, mass spectra, UV-Vis spectra and X-ray crystallography, respec- tively. The crystal of 3a belongs to monoclinic, space group P21/n with a = 9.321(3) ? b = 11.046(4) ? c = 24.335(9) ? b =92.649(7), V = 2502.7(16) ?, Z = 4, m = 0.078 mm-1, Dc =1.230 g/cm3, F(000) = 984, the final R = 0.0590 and wR = 0.1316 for 4367 observed reflections with I > 2s(I). The crystal of 3b belongs to monoclinic, space group P21/c with a = 10.637(4) ? b = 24.138(10) ? c = 10.398(4) ? b = 104.913(8), V = 2579.8(17) ?, Z = 4, m = 0.075 mm-1, Dc = 1.194 g/cm3, F(000) = 984, the final R =0.0631 and wR =0.1006 for 4463 observed reflections with I > 2s(I). X-ray crystallography revealed that the nitrogen atom in the triarylamine moiety is of sp2 hybridization with the three phenyl rings twisted to each other.
文摘The coastal seawater of Mediterranean of Alexandria receives large amount of discharged waters containing industrial wastes, sewage, and agricultural and domestic drainage. Fluoride and some parameters were(chemical and physical) determined. The data gave indication that the content and the amount of the discharged water largely affect the chemical composition of the coastal water. Stepwise regression analysis was highly significant and the model was very fruitful, where the observed and calculated values were mostly concordant. This may indicated that there was a relation between fluoride content in coastal seawater and its content in the discharged water.
文摘The molecular structure of the title compound, ph3AsC (COCH3 )Seph, has been determined by X--ray diffraction. Crystallographic data: Mr= 517. 36'monoclinic, P21,/c, a=11. 499(4), b=9. 619(4), c=20. 919(7),A, β=98. 82(2)°,V= 2286(l) A 3, Z=4, Dc= 1. 509 g/cm3, μ(MoKa) = 3. 073 cm-1, F(000) = 1040and the final R=0. 042, Rw= 0. 041. In the molecule, the geometry of arsenic atom isa distorted tetrahedron, the bonds of Se--C (3) and As--C(31 ) have striking characteristics of double bond, the delocalization of electronic density occurs to be restrictedfrom O(1 ) to Se atoms.
基金This project is financially supported by the National Nature Science Foundation of China (No. 59804004) and (No.50274046)
文摘A new process of enriching germanium from coal ash was developed. The processinvolves in mixing the coal ash and ammonium chloride and then roasting the mixture to producegermanium chloride that is then absorbed by dilute hydrochloric acid and hydrolyzed to germaniumoxide. The germanium recovery reached to 80.2% at the optimum condition: mass ratio of NH_4Cl/coalash is 0.15, roasting temperature 400℃ and roasting time 90 min.
文摘The title complex, C15S2Cl2H16Pd, Mr = 437. 73, crystallizes in monoclinic space group P21/c with a = 10. 177(2), b=10. 788(1), c= 15. 305(1) (?),β=102. 73(1)°, V = 1638. 1(?)3, Z = 4, Dx =1.77g/cm3, μ = 16.8cm-1, F (000) = 872. The final structure refinement converged with unweighted and weighted R factors of 0. 025 and 0. 033 for 2490 observed unique reflections. The complex has mononuclear structure with the ligand cis-chelated to the Pd(Ⅱ) atom.
基金This work was financially supported by the National Natural Science Foundation of China. The number of the project is 5989914. The authors are grateful to Ms. Ping Wan for English diction.
文摘Regularity of the initial atmospheric corrosion of A3 steel in the presence of NaCI was investigated. The results showed that NaCI can accelerate the corrosion of A3 steel. Dry mass gain of A3 steel in the presence of NaCI deposition increases with the exposure time, which can be correlated by using exponential decay function. The relationship between dry mass gain and amount of NaCI deposition at a certain exposure time follows a quadratic function. More amount of NaCI deposition will slow down the corrosion rate to some extent after exposure for a certain time. SEM/EDAX was used to characterize the corrosion surface and products. The surfaces of the NaCI treated A3 steel were obviously uneven, and some tiny crevices appear in the corrosion products that could help O2 transmit to the inner layer. The amount of oxygen in atomic percentage in the corrosion products increases with the amount of NaCI deposition.
基金The authors would like to acknowledge Agilent Technologies for providing the capillary electrophoresis system and Bioanalytical System for present of sulfated b-CD. The study is supported by NSFC Grant No. 29875001.
文摘A capillary electrophoresis (CE) method has been firstly used for the separation of the therapeutically important xanthones from Securidaca inappendiculata. The separation of the nine xanthones was systematically optimized with respect to pH, concentration of running buffers, addition of sulfated b-CD, applied voltage and column temperature. Baseline separation was achieved for the nine xanthones in less than 15 minutes using a background electrolyte consisting of 200 mmol/L borate (pH 9.5) and 10 mmol/L sulfated b-CD.
文摘The interaction between CH3OH and H2CO has been studied by ab ini-tio method at the level of STO-3G and 6-311G basis sets. It has been found that there are two possible complexes; a hydrogen bonded complex CH3OH...CH2O(Ⅰ) and an electron donor-acceptor complex CH3OH.....OCH2(Ⅱ).The stabilization energies of (Ⅰ) and (Ⅱ) are 14. 6 and 3. 6kJ/mol (STO-3G results) or 25. 1 and 17. 1kJ/mol (6-311G results) respectively. The nature of these complexes has been discussed by using the energy decomposition scheme.
基金Supported by the National Natural Science Foundation of China (No. 29875002) and the Natural Science Foundation of Beijing (No. 2002017).
文摘The structure and proton conducting mechanism of solid polymer electrolyte (SPE) are described. Since the conductivity of electrolyte is important in SPE electrochemical cell research and development, we investigate quantitatively the conductivity of Nafion membrane and its dependence on temperature and relative humidity. Experimental results show that the conductivity of Nafion membrane increases with temperature and relative humidity. We also reports on the preparation and development of SPE membrane electrode with the emphasis on the mixture pressing method and impregnation-reduction process to prepare SPE composite electrode assemblies and their application to electrochemical sensors. We also investigate and fabricate a potentiometric electrochemical sensor of hydrogen and ethylene to measure the hydrogen and ethylene partial pressure.
基金Supported by the National Natural Science Foundation of China (No.29976035) and Zhejiang and Fujian Provincial Natural Science Foundation of China.
文摘Necessary and sufficient conditions for azeotropy in reactive mixtures are derived in terms of elemental composition, which shows that in the space of elemental compositions, they take the same functional form as the conditions for azeotropy in non-reactive mixtures. The production of methyl tert-butyl ether (MTBE) is taken as an example. It is found that there are a 'pseudo' intermediate-boiling ternary reactive azeotrope at p = 101.325kPa and two 'real' ternary reactive azeotropes at p = 101.325 Pa. The introduced elemental compositions also reduce the dimensionality of the phase diagrams and provide a natural set of variables for visualization of phase behavior.
文摘A new MEEKC method assisted with pressure-driven mobile phase was presented for the separation of felted explosives. Microemulsion solution was composed of 80 mmol/L heptane -120 mmol/L SDS (sodium dodecyl sulphate) - 900 mmol/L butanol - 10 mmol/L borate at pH 9.4 and a pressure-driven flow of 0.020 mL/min under 1.3 MPa was employed to manipulate the separation. Explosives HMX (1, 3, 5, 7-tetranitro-l, 3, 5, 7-tetrazacyclooctane) and TATB (triamino-trinitrobenzene), which were felted on fluorine rubber F2311 (polytrifluorochlorethylene and polyvinylidene fluoride 1/1 co-polymerization) and F2314 (polytrifluorochlorethylene and polyvinylidene fluoride 4/1 co-polymerization) were well separated with very good peak shapes.
