In this paper, the saturated solution crystallization method is proposed to promote the formation of hydrate by means of the known similarities between the hydrate formation process and the crystallization process. In...In this paper, the saturated solution crystallization method is proposed to promote the formation of hydrate by means of the known similarities between the hydrate formation process and the crystallization process. In this method,adding the second phase crystals was used to replace the spontaneous formation of hydrate crystal nuclei to form hydrate.The effects of saturated Na_2SO_4, MgSO_4, NH_4HCO_3 and CuSO_4 solutions on the formation rates of natural gas hydrate and gas storage capacity were investigated. The results showed that the saturated solution had an influence on the hydrate formation process. Under the given experimental conditions, the saturated Na_2SO_4 solution showed a highest increase in the hydrate formation rate, and the average hydrate formation rate in its presence was 11.8 times higher than that obtained in the deionized water. Moreover, the largest formation rate of gas hydrates observed in the saturated Na_2SO_4 solution was 386 times bigger than that in the deionized water, and the gas storage capacity increased by 10 times. In addition, the average hydrate formation rate in the saturated Mg SO_4 solution was faster than that in water by 20 times. The largest formation rate of gas hydrates in the saturated MgSO_4 solution was 165 times faster than that obtained in the deionized water, and the gas storage capacity increased by 6.2 times. The saturated NH_4HCO_3 and saturated CuSO_4 solutions also influenced the formation process of hydrate. Therefore, the crystallization method of saturated solution can be used to achieve a highefficiency preparation of natural gas hydrates, which provides theoretical guidance for the storage of natural gas in the form of hydrate.展开更多
used－silical capillary columns containing heptakis（2、3、6－tri－o－pentyl）-β-cyclodextrinand dibenzo-18-crown-6 were prepared．By studying the selectivity of mixed stationary phases forsome solute pairs.as well a...used－silical capillary columns containing heptakis（2、3、6－tri－o－pentyl）-β-cyclodextrinand dibenzo-18-crown-6 were prepared．By studying the selectivity of mixed stationary phases forsome solute pairs.as well as comparing with the heptakis（2．3、6-tri-O-pentyl）-β-cyclodextrin and thedibenzo-18-crown-6 used as individual stationary phase、the synergistic effects were observed.These effects were affected by the column temperature．mixed ratio and linear velocity of carrier gas．展开更多
Heptakis(2.6-di-O-pentyl-3-O-ally)-β-cyclodextrin as an excellent gas chromatographic stationary phase separating phenol and cresol isomers is described.
Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pres-sure was investigated.The effects of temperature,salt species,salt concentration,solids content,pH and modifier w...Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pres-sure was investigated.The effects of temperature,salt species,salt concentration,solids content,pH and modifier were examined.The crystals obtained under different conditions and solubility of calcium sulfate in contact with solid gypsum were also determined.α-Calcium sulfate hemihydrate crystals of stubby columnar shape and regular pentahedral sides were obtained under the following conditions：salt concentration 20%-30%,operation tempera-ture 95-100 °C,solids mass content in the slurry 10%-30% and neutral pH.Thermodynamic analysis revealed that phase transformation of calcium sulfate dihydrate to α-calcium sulfate hemihydrate occurs because of the difference in solubilities between the two solid gypsum phases in this system.展开更多
建立了一种可用于水产品及食用油中氟乐灵残留量分析的分散型固相萃取-气相色谱-负化学离子源质谱方法。水产品及食用油经乙腈提取，4℃冷藏后，采用分散型固相萃取法净化，由气相色谱-负化学离子源质谱选择离子监测技术进行测定与确证...建立了一种可用于水产品及食用油中氟乐灵残留量分析的分散型固相萃取-气相色谱-负化学离子源质谱方法。水产品及食用油经乙腈提取，4℃冷藏后，采用分散型固相萃取法净化，由气相色谱-负化学离子源质谱选择离子监测技术进行测定与确证，同位素内标法定量。在1～40μg / L 范围内氟乐灵农药的线性关系良好；方法定量限（LOQ）为0.02μg / kg；对鳗鱼、烤鳗、梭子蟹、小龙虾、猪油和橄榄油等6种复杂基质进行1.0、2.0和3.0μg / kg 等3个水平的添加回收试验，平均回收率均处于80％～100％之间，RSD≤10.3％；无干扰现象出现。该方法可作为水产品及食用油中氟乐灵残留检测的确证方法。展开更多
The intermediate YBa2Cu3O7-δ samples of single phase with transitional structure from tetragonal phase to orthorhombic phase are prepared by quenching at different temperatures and investigated systematically. From X...The intermediate YBa2Cu3O7-δ samples of single phase with transitional structure from tetragonal phase to orthorhombic phase are prepared by quenching at different temperatures and investigated systematically. From X-ray diffraction (XRD), R-T curve and ac susceptibility measurements, it can be concluded that the structure transits from tetragonal phase to orthorhombic phase as the quenching temperature decreases; the YBa2Cu2O7-δ samples with tetragonal phase are nonsuperconductive till 4.2K; the critical temperature depends on the degree of orthorhombic distortion in the intermediate samples; the possible existence of a structure phase transition near 100K for the non-superconductive tetragonal phase is discovered for the first time. The electrical conductance property at high temperature region (higher than 100K) for the samples quenched at higher temperature can be explained in terms of the affection of oxygen vacancies.展开更多
Unsymmetrical dimesogenic compounds with cholesteryl and 4-（trans-4-n-alkylcyclohexyl）phenoxy parts were synthesized by condensation of cholester-3-yl 6-bromohexanoate with appropriate 4-（trans-4-n-alkylcyclohexyl...Unsymmetrical dimesogenic compounds with cholesteryl and 4-（trans-4-n-alkylcyclohexyl）phenoxy parts were synthesized by condensation of cholester-3-yl 6-bromohexanoate with appropriate 4-（trans-4-n-alkylcyclohexyl）- phenols. Structures and thermal phase behaviour of these dimesogenic compounds have been confirmed by IR, IH NMR, elemental analysis, DSC, polarity microscopy and XRD measurements. Their thermal phase behaviour was significantly different with that of other cholesterol-based dimesogens while they exhibited low and wide phase transition temperature.展开更多
The structure of 4-amino-3-(5-tetrazolate)-fiirazan(HAFT) was characterized by single crystal X-ray diffraction. The thermal decomposition process of HAFT was investigated by MS-FTIR-DSC-TG coupling technique. The res...The structure of 4-amino-3-(5-tetrazolate)-fiirazan(HAFT) was characterized by single crystal X-ray diffraction. The thermal decomposition process of HAFT was investigated by MS-FTIR-DSC-TG coupling technique. The result shows that the exothermic process occurs from 278.7-350℃, with a peak temperature of 324.7℃. The thennal decomposition gaseous products of HAFT are NO2, CO2, HCN, CO, NH3 and H2O. The detonation velocity and detonation pressure of HAFT were calculated by the nitrogen equivalent equation. The detonation velocity of HAFT is 7727.46 m/s, which is higher than that of TNT(7178 m/s). The detonation pressure of HAFT(25.27 GPa) is satisfactory. The sensitivity tests reveal HAFT possesses excellent insensitivities to impact and friction.展开更多
SrxBi1-xFeO3- (SBF) series mixed conductors were synthesized using Standard ceramic method. The properties of such materials were characterized by XRD, O2-TPD techniques. Ab-normal crystal phenomena were found and exp...SrxBi1-xFeO3- (SBF) series mixed conductors were synthesized using Standard ceramic method. The properties of such materials were characterized by XRD, O2-TPD techniques. Ab-normal crystal phenomena were found and explained and correlated with the oxygen permeation results. By analysis of the critical radius (rc), the degree of openness of the lattice (Fv) and the average metal-oxygen bonding energy of the perovskite lattice (ABE), it was proposed that the oxygen permeation flux is determined mainly by the oxygen diffusion rate in bulk when 1-x≤0.5, and by the concentration of oxygen vacancy when 1-x≥ 0.5. The stability of Sr0.5Bi0.5FeO3- was also investigated, and the high stability of it was attributed to the stable BO6 octahedra.展开更多
基金the Program for Liaoning Excellent Talents in University (LJQ2014038)the Natural Science Foundation of Liaoning Province (201602470)
文摘In this paper, the saturated solution crystallization method is proposed to promote the formation of hydrate by means of the known similarities between the hydrate formation process and the crystallization process. In this method,adding the second phase crystals was used to replace the spontaneous formation of hydrate crystal nuclei to form hydrate.The effects of saturated Na_2SO_4, MgSO_4, NH_4HCO_3 and CuSO_4 solutions on the formation rates of natural gas hydrate and gas storage capacity were investigated. The results showed that the saturated solution had an influence on the hydrate formation process. Under the given experimental conditions, the saturated Na_2SO_4 solution showed a highest increase in the hydrate formation rate, and the average hydrate formation rate in its presence was 11.8 times higher than that obtained in the deionized water. Moreover, the largest formation rate of gas hydrates observed in the saturated Na_2SO_4 solution was 386 times bigger than that in the deionized water, and the gas storage capacity increased by 10 times. In addition, the average hydrate formation rate in the saturated Mg SO_4 solution was faster than that in water by 20 times. The largest formation rate of gas hydrates in the saturated MgSO_4 solution was 165 times faster than that obtained in the deionized water, and the gas storage capacity increased by 6.2 times. The saturated NH_4HCO_3 and saturated CuSO_4 solutions also influenced the formation process of hydrate. Therefore, the crystallization method of saturated solution can be used to achieve a highefficiency preparation of natural gas hydrates, which provides theoretical guidance for the storage of natural gas in the form of hydrate.
文摘used－silical capillary columns containing heptakis（2、3、6－tri－o－pentyl）-β-cyclodextrinand dibenzo-18-crown-6 were prepared．By studying the selectivity of mixed stationary phases forsome solute pairs.as well as comparing with the heptakis（2．3、6-tri-O-pentyl）-β-cyclodextrin and thedibenzo-18-crown-6 used as individual stationary phase、the synergistic effects were observed.These effects were affected by the column temperature．mixed ratio and linear velocity of carrier gas．
文摘Heptakis(2.6-di-O-pentyl-3-O-ally)-β-cyclodextrin as an excellent gas chromatographic stationary phase separating phenol and cresol isomers is described.
基金Supported by the National High Technology Research and Development Program of China（2006AA06Z385） the Science Foundation of Wuhan University of Science and Technology（2008RC06）
文摘Direct phase transformation of flue gas desulfurization gypsum in hot salt solution at atmospheric pres-sure was investigated.The effects of temperature,salt species,salt concentration,solids content,pH and modifier were examined.The crystals obtained under different conditions and solubility of calcium sulfate in contact with solid gypsum were also determined.α-Calcium sulfate hemihydrate crystals of stubby columnar shape and regular pentahedral sides were obtained under the following conditions：salt concentration 20%-30%,operation tempera-ture 95-100 °C,solids mass content in the slurry 10%-30% and neutral pH.Thermodynamic analysis revealed that phase transformation of calcium sulfate dihydrate to α-calcium sulfate hemihydrate occurs because of the difference in solubilities between the two solid gypsum phases in this system.
文摘建立了一种可用于水产品及食用油中氟乐灵残留量分析的分散型固相萃取-气相色谱-负化学离子源质谱方法。水产品及食用油经乙腈提取，4℃冷藏后，采用分散型固相萃取法净化，由气相色谱-负化学离子源质谱选择离子监测技术进行测定与确证，同位素内标法定量。在1～40μg / L 范围内氟乐灵农药的线性关系良好；方法定量限（LOQ）为0.02μg / kg；对鳗鱼、烤鳗、梭子蟹、小龙虾、猪油和橄榄油等6种复杂基质进行1.0、2.0和3.0μg / kg 等3个水平的添加回收试验，平均回收率均处于80％～100％之间，RSD≤10.3％；无干扰现象出现。该方法可作为水产品及食用油中氟乐灵残留检测的确证方法。
文摘The intermediate YBa2Cu3O7-δ samples of single phase with transitional structure from tetragonal phase to orthorhombic phase are prepared by quenching at different temperatures and investigated systematically. From X-ray diffraction (XRD), R-T curve and ac susceptibility measurements, it can be concluded that the structure transits from tetragonal phase to orthorhombic phase as the quenching temperature decreases; the YBa2Cu2O7-δ samples with tetragonal phase are nonsuperconductive till 4.2K; the critical temperature depends on the degree of orthorhombic distortion in the intermediate samples; the possible existence of a structure phase transition near 100K for the non-superconductive tetragonal phase is discovered for the first time. The electrical conductance property at high temperature region (higher than 100K) for the samples quenched at higher temperature can be explained in terms of the affection of oxygen vacancies.
基金Project supported by the National Natural Science Foundation of China （No. 20462001）.
文摘Unsymmetrical dimesogenic compounds with cholesteryl and 4-（trans-4-n-alkylcyclohexyl）phenoxy parts were synthesized by condensation of cholester-3-yl 6-bromohexanoate with appropriate 4-（trans-4-n-alkylcyclohexyl）- phenols. Structures and thermal phase behaviour of these dimesogenic compounds have been confirmed by IR, IH NMR, elemental analysis, DSC, polarity microscopy and XRD measurements. Their thermal phase behaviour was significantly different with that of other cholesterol-based dimesogens while they exhibited low and wide phase transition temperature.
基金Supported by the National Natural Science Foundation of China(No.21241003)the Natural Science Foundation of Shaanxi Province,China(No.2018JM2061).
文摘The structure of 4-amino-3-(5-tetrazolate)-fiirazan(HAFT) was characterized by single crystal X-ray diffraction. The thermal decomposition process of HAFT was investigated by MS-FTIR-DSC-TG coupling technique. The result shows that the exothermic process occurs from 278.7-350℃, with a peak temperature of 324.7℃. The thennal decomposition gaseous products of HAFT are NO2, CO2, HCN, CO, NH3 and H2O. The detonation velocity and detonation pressure of HAFT were calculated by the nitrogen equivalent equation. The detonation velocity of HAFT is 7727.46 m/s, which is higher than that of TNT(7178 m/s). The detonation pressure of HAFT(25.27 GPa) is satisfactory. The sensitivity tests reveal HAFT possesses excellent insensitivities to impact and friction.
文摘SrxBi1-xFeO3- (SBF) series mixed conductors were synthesized using Standard ceramic method. The properties of such materials were characterized by XRD, O2-TPD techniques. Ab-normal crystal phenomena were found and explained and correlated with the oxygen permeation results. By analysis of the critical radius (rc), the degree of openness of the lattice (Fv) and the average metal-oxygen bonding energy of the perovskite lattice (ABE), it was proposed that the oxygen permeation flux is determined mainly by the oxygen diffusion rate in bulk when 1-x≤0.5, and by the concentration of oxygen vacancy when 1-x≥ 0.5. The stability of Sr0.5Bi0.5FeO3- was also investigated, and the high stability of it was attributed to the stable BO6 octahedra.
