Four polyoxometalate complexes, （CPFX·HCl）3H4SiW<sup>12 O<sup>40 , （CPFX·HCl）3H3PW<sup>12 O<sup>40 , （CPFX·HCl）3H3PMo<sup>12 O<sup>40 and （CPFX·HCl）4H4Si...Four polyoxometalate complexes, （CPFX·HCl）3H4SiW<sup>12 O<sup>40 , （CPFX·HCl）3H3PW<sup>12 O<sup>40 , （CPFX·HCl）3H3PMo<sup>12 O<sup>40 and （CPFX·HCl）4H4SiMo<sup>12 O<sup>40 , were prepared from ciprofloxacin hydrochloride（CPFX·HCl） reacting with HnXM<sup>12 O<sup>40 ·nH2O（X=P,Si; M=W,Mo） in an aqueous solution, and characterized by elemental analysis, IR spectrometry and TG-DTA. The IR spectrum confirms the presence of Keggin-type anions of heteropoly acids and the characteristic functional groups of ciprofloxacin. The TG/DTA curves show that their thermal decomposition is a multi-step process including simultaneous collapse of the Keggin-type structure. At first, these compounds had a mass loss of water molecules, then several other mass losses occured due to the decomposition of ciprofloxacin hydrochloride and its fragments with the degradation of Keggin anions. The end product of decomposition is the mixture of WO3（or MoO3） and SiO2（or P2O5）, identified by X-ray diffraction and IR spectroscopy. The possible thermal decomposition mechanisms of these complexes are proposed. This study exemplified that the thermal stability of the complexes containing tungsten is much better than that of the complexes containing molybdenum.展开更多
The experimental results of the thermal conductivities of xonotlite-type calcium silicate insulation materials were pre-sented at different temperatures and pressures. Two appropriative surroundings, i.e. an elevated ...The experimental results of the thermal conductivities of xonotlite-type calcium silicate insulation materials were pre-sented at different temperatures and pressures. Two appropriative surroundings, i.e. an elevated temperature surrounding from ambi-ent temperature to 1450 K and a vacuum surrounding from atmosphere pressure to 10-3 Pa, were designed for the transient hot-strip (THS) method. The thermal conductivities of xonotlite-type calcium silicate with four densities from ambient temperature to 1000 K and 0.045 Pa to atmospheric pressure were measured. The results show that the thermal conductivity of xonotlite-type calcium sili-cate decreases apparently with the fall of density, and decreases apparently with the drop of pressure, and reaches the least value at about 100 Pa. The thermal conductivity of xonotlite-type calcium silicate increases almost linearly with T3, and increases more abundantly with low density than with high density. The thermal conductivity measurement uncertainty is estimated to be approxi-mately 3% at ambient temperature, and 6% at 800 K.展开更多
Thermal performance is the most important factor in the development of a borehole heat exchanger utilizing geothermal energy.The thermal performance is affected by many different design parameters and different operat...Thermal performance is the most important factor in the development of a borehole heat exchanger utilizing geothermal energy.The thermal performance is affected by many different design parameters and different operating conditions such as bleeding.This eventually determines the operation and cost efficiency of the borehole heat exchanger system.The thermal performance of an open standing column well (SCW) type geothermal heat exchanger was assessed under the influence of bleeding.For this,a thermal response test rig was established with line-source theory.The test rig also had a bleeding function by releasing fluid while taking additional underground water through the heat exchanger.The thermal response test was performed with an additional constant input heat source.Effective thermal conductivity and thermal resistance were obtained from the measured data.From the measurement,the effective thermal conductivity is found to have 1.47 times higher value when bleeding is applied.The thermal resistance also increases by 1.58 times compared to a non-bleeding case.This trend indicates enhanced heat transfer in the SCW type heat exchanger with a bleeding function.Bleeding,therefore,could be an effective method of achieving a high heat transfer rate in the SCW type heat exchanger with sufficient underground water supply.展开更多
The curvature type of the thermal lens generated in a zigzag slab laser is numerically analysed.It is found that the curvature type of the thermal lens varies alternatively between the convex and the concave lenses wi...The curvature type of the thermal lens generated in a zigzag slab laser is numerically analysed.It is found that the curvature type of the thermal lens varies alternatively between the convex and the concave lenses with the number of bounces of light within the slab,which can be well explained by the trace of the zigzag propagation.In addition, we conclude that the beamlet with a larger number of bounces experiences weaker thermal lensing but more serious wavefront deformation due to the large side lobe portion in the curve of optical path difference.展开更多
The dried gel of SrFe 12O 19, prepared by citrate approach, was investigated by means of infrared spectroscopy （IR）, thermogravimetric analysis（TG）, differential scanning calorimetry（DSC）, X-ray diffraction（XRD...The dried gel of SrFe 12O 19, prepared by citrate approach, was investigated by means of infrared spectroscopy （IR）, thermogravimetric analysis（TG）, differential scanning calorimetry（DSC）, X-ray diffraction（XRD） techniques, energy dispersive spectroscopy（EDS）, and transmission electron microscopy（TEM）. The thermal instability and the thermal decomposition of low-temperature strontium M-type hexaferrite crystallized at about 600 ℃ were confirmed for the first time by XRD method. The decomposition of the low-temperature strontium M-type hexaferrite took place at about 688.6 ℃ determined by DSC investigation. The low-temperature strontium M-type hexaferrite nanoparticles were decomposed into SrFeO 2.5 with an orthorthombic cell and Fe2O3 with a tetragonal cell as well as possibl α-Fe2O3. The agglomerated particles with sizes less than 200 nm obtained at 800 ℃ were plesiomorphous to strontium M-type hexaferrite. The thermally stable strontium M-type hexaferrite nanoparticles with sizes less than 100nm could take place at 900 ℃. Up to 1000 ℃, the phase transformation to form strontium M-type hexaferrite was ended, the calcinations with the sizes more than 1μm were composed of α-Fe2O3 and strontium M-type hexaferrite. The method of distinguishing γ-Fe2O3 with a spinel structure from Fe2O3 with tetragonal cells by using powder XRD method was proposed. Fe2O3 with tetragonal cells to be crystallized before the crystallization of thermally stable strontium M-type hexaferrite was confirmed for the first time. The reason why α-Fe2O3 as an additional phase appears in the calcinations is the cationic vacancy of strontium M-type hexaferrite, SrFe 12-xxO 19 （0≤x≤0.5）.展开更多
文摘Four polyoxometalate complexes, （CPFX·HCl）3H4SiW<sup>12 O<sup>40 , （CPFX·HCl）3H3PW<sup>12 O<sup>40 , （CPFX·HCl）3H3PMo<sup>12 O<sup>40 and （CPFX·HCl）4H4SiMo<sup>12 O<sup>40 , were prepared from ciprofloxacin hydrochloride（CPFX·HCl） reacting with HnXM<sup>12 O<sup>40 ·nH2O（X=P,Si; M=W,Mo） in an aqueous solution, and characterized by elemental analysis, IR spectrometry and TG-DTA. The IR spectrum confirms the presence of Keggin-type anions of heteropoly acids and the characteristic functional groups of ciprofloxacin. The TG/DTA curves show that their thermal decomposition is a multi-step process including simultaneous collapse of the Keggin-type structure. At first, these compounds had a mass loss of water molecules, then several other mass losses occured due to the decomposition of ciprofloxacin hydrochloride and its fragments with the degradation of Keggin anions. The end product of decomposition is the mixture of WO3（or MoO3） and SiO2（or P2O5）, identified by X-ray diffraction and IR spectroscopy. The possible thermal decomposition mechanisms of these complexes are proposed. This study exemplified that the thermal stability of the complexes containing tungsten is much better than that of the complexes containing molybdenum.
基金supported by the National Natural Science Foundation of China (No.50806021)
文摘The experimental results of the thermal conductivities of xonotlite-type calcium silicate insulation materials were pre-sented at different temperatures and pressures. Two appropriative surroundings, i.e. an elevated temperature surrounding from ambi-ent temperature to 1450 K and a vacuum surrounding from atmosphere pressure to 10-3 Pa, were designed for the transient hot-strip (THS) method. The thermal conductivities of xonotlite-type calcium silicate with four densities from ambient temperature to 1000 K and 0.045 Pa to atmospheric pressure were measured. The results show that the thermal conductivity of xonotlite-type calcium sili-cate decreases apparently with the fall of density, and decreases apparently with the drop of pressure, and reaches the least value at about 100 Pa. The thermal conductivity of xonotlite-type calcium silicate increases almost linearly with T3, and increases more abundantly with low density than with high density. The thermal conductivity measurement uncertainty is estimated to be approxi-mately 3% at ambient temperature, and 6% at 800 K.
基金Project supported by the Second Stage of Brain Korea 21 Projects and Changwon National University in2011-2012
文摘Thermal performance is the most important factor in the development of a borehole heat exchanger utilizing geothermal energy.The thermal performance is affected by many different design parameters and different operating conditions such as bleeding.This eventually determines the operation and cost efficiency of the borehole heat exchanger system.The thermal performance of an open standing column well (SCW) type geothermal heat exchanger was assessed under the influence of bleeding.For this,a thermal response test rig was established with line-source theory.The test rig also had a bleeding function by releasing fluid while taking additional underground water through the heat exchanger.The thermal response test was performed with an additional constant input heat source.Effective thermal conductivity and thermal resistance were obtained from the measured data.From the measurement,the effective thermal conductivity is found to have 1.47 times higher value when bleeding is applied.The thermal resistance also increases by 1.58 times compared to a non-bleeding case.This trend indicates enhanced heat transfer in the SCW type heat exchanger with a bleeding function.Bleeding,therefore,could be an effective method of achieving a high heat transfer rate in the SCW type heat exchanger with sufficient underground water supply.
基金supported by the National Natural Science Foundation of China(Grant Nos.50721004 and 60978032)
文摘The curvature type of the thermal lens generated in a zigzag slab laser is numerically analysed.It is found that the curvature type of the thermal lens varies alternatively between the convex and the concave lenses with the number of bounces of light within the slab,which can be well explained by the trace of the zigzag propagation.In addition, we conclude that the beamlet with a larger number of bounces experiences weaker thermal lensing but more serious wavefront deformation due to the large side lobe portion in the curve of optical path difference.
文摘The dried gel of SrFe 12O 19, prepared by citrate approach, was investigated by means of infrared spectroscopy （IR）, thermogravimetric analysis（TG）, differential scanning calorimetry（DSC）, X-ray diffraction（XRD） techniques, energy dispersive spectroscopy（EDS）, and transmission electron microscopy（TEM）. The thermal instability and the thermal decomposition of low-temperature strontium M-type hexaferrite crystallized at about 600 ℃ were confirmed for the first time by XRD method. The decomposition of the low-temperature strontium M-type hexaferrite took place at about 688.6 ℃ determined by DSC investigation. The low-temperature strontium M-type hexaferrite nanoparticles were decomposed into SrFeO 2.5 with an orthorthombic cell and Fe2O3 with a tetragonal cell as well as possibl α-Fe2O3. The agglomerated particles with sizes less than 200 nm obtained at 800 ℃ were plesiomorphous to strontium M-type hexaferrite. The thermally stable strontium M-type hexaferrite nanoparticles with sizes less than 100nm could take place at 900 ℃. Up to 1000 ℃, the phase transformation to form strontium M-type hexaferrite was ended, the calcinations with the sizes more than 1μm were composed of α-Fe2O3 and strontium M-type hexaferrite. The method of distinguishing γ-Fe2O3 with a spinel structure from Fe2O3 with tetragonal cells by using powder XRD method was proposed. Fe2O3 with tetragonal cells to be crystallized before the crystallization of thermally stable strontium M-type hexaferrite was confirmed for the first time. The reason why α-Fe2O3 as an additional phase appears in the calcinations is the cationic vacancy of strontium M-type hexaferrite, SrFe 12-xxO 19 （0≤x≤0.5）.
