The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission elect...The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission electron microscopy(HR-TEM) and N2 adsorption desorption and adsorption are used to study the effects of the synthesized process condition on the microstructure of the as-synthesized mesoporous Ti O2. The photocatalytic performances of as-synthesized samples are evaluated by the degradation of the formaldehyde under ultraviolet light irradiations. The results demonstrate that the as-synthesized mesoporous Ti O2 are anatase with the uniform size about 20-40 nm. The sample is prepared using cetyltrimethyl ammonium bromide(CTAB) as the template with average pore size distribution of 8.12 nm, specific surface area of 68.47 m2/g and pore volume of 0.213 m L/g. The samples show decomposition of formaldehyde 95.8% under ultraviolet light irradiations for 90 min. These results provide a basic experimental process for preparation mesoporous Ti O2, which will posses a broad prospect in terms of the applications in improving indoor air quality.展开更多
The effects of surface-induced evaporative cooling on an atom chip are investigated. The evolutions of temperature, number and phase-space density of the atom cloud are measured when the atom cloud is brought close to...The effects of surface-induced evaporative cooling on an atom chip are investigated. The evolutions of temperature, number and phase-space density of the atom cloud are measured when the atom cloud is brought close to the surface. Rapid decrease of the temperature and number of the atoms is found when the atom-surface distance is 〈 100 ttm. A gain of about a factor of five on the phase-space density is obtained. It is found that the efficiency of the surface-induced evaporative cooling depends on the atom-surface distance and the shape of the evaporative trap. When the atoms are moved very close to the surface, severe heating is observed, which dominates when the holding time is 〉 8 ms. It is important that the surface-induced evaporative cooling offers novel possibilities for the realization of a continuous condensation, where a spatially varying evaporative cooling is required.展开更多
Volatile organic solvents were considered to have little influence on the synthesis of mesostructured materials through evaporation-induced self-assembly(EISA),because upon evaporation they leave the sol and hence do ...Volatile organic solvents were considered to have little influence on the synthesis of mesostructured materials through evaporation-induced self-assembly(EISA),because upon evaporation they leave the sol and hence do not interfere with the self-assembly process.We show here that the choice of solvent is crucial in the synthesis of thin films of phenylene-bridged periodic mesoporous organosilica(benzene PMO).Methanol is found to be a better solvent for the synthesis of thin films,whereas ethanol favors the formation of(HO)3Si-C6H4-Si(OH)3 crystals,the identity and structure of which is established by X-ray diffraction.A ternary reactant composition diagram is designed to visualize the relationship among multiple synthesis experiments and to guide the interpretation of experimental results and optimization of the quality of the periodic mesoporous organosilica film.Our study highlights the importance of solvent choice,a factor often neglected in EISA.We expect it to inspire researchers to explore the effect of solvent in designing the synthesis of mesoporous materials.展开更多
Al2O3 films were prepared using electron beam evaporation at room temperature. The samples were irradiated with oxygen plasma under different energy. The variations in average surface defect density and root mean squa...Al2O3 films were prepared using electron beam evaporation at room temperature. The samples were irradiated with oxygen plasma under different energy. The variations in average surface defect density and root mean square (RMS) surface roughness were characterized using an optical microscope and an atomic force microscope. Surface average defect density increased after plasma treatment. The RMS surface roughness of the samples decreased from 1.92 nm to 1.26 nm because of surface atom restructuring after oxygen plasma conditioning. A 355 nm laser-induced damage experiment indicated that the as-grown sample with the lowest defect density exhibited a higher laser-induced damage threshold (1.12 J/cm2) than the other treated samples. Laser-induced damage images revealed that defect is one of the key factors that affect laser-induced damage on Al2O3 films.展开更多
Volatile organic solvents were considered to have little influence on the synthesis of mesostructured materials through evaporation-induced self-assembly(EISA),because upon evaporation they leave the sol and hence do ...Volatile organic solvents were considered to have little influence on the synthesis of mesostructured materials through evaporation-induced self-assembly(EISA),because upon evaporation they leave the sol and hence do not interfere with the self-assembly process.We show here that the choice of solvent is crucial in the synthesis of thin films of phenylene-bridged periodic mesoporous organosilica(benzene PMO).Methanol is found to be a better solvent for the synthesis of thin films,whereas ethanol favors the formation of(HO)3Si-C6H4-Si(OH)3 crystals,the identity and structure of which is established by X-ray diffraction.A ternary reactant composition diagram is designed to visualize the relationship among multiple synthesis experiments and to guide the interpretation of experimental results and optimization of the quality of the periodic mesoporous organosilica film.Our study highlights the importance of solvent choice,a factor often neglected in EISA.We expect it to inspire researchers to explore the effect of solvent in designing the synthesis of mesoporous materials.展开更多
A novel and efficient methodology for obtaining highly active photocatalyst of bi phase TiO 2 with small particle size and high specific surface area was developed by solvent evaporation induced crystallization (SE...A novel and efficient methodology for obtaining highly active photocatalyst of bi phase TiO 2 with small particle size and high specific surface area was developed by solvent evaporation induced crystallization (SEIC) method at low temperature. The prepared TiO 2 powder was characterized with X ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface areas. The photocatalytic activity was evaluated by the photocatalytic oxidation of acetone in air. The results showed that the photocatalytic activity of the TiO 2 powder prepared by this method approached that of Degussa P25. This may be attributed to the fact that the prepared TiO 2 powder had larger specific surface areas (265 m 2·g -1 ) and smaller crystallite size (about 5 nm), but relatively low crystallinity, as compared with Degussa P25.展开更多
By using semiclassical theory combined with multiple-scale method, we analytically study the linear absorption and the nonlinear dynamical properties in a lifetime broadened Λ-type three-level self-assembled quantum ...By using semiclassical theory combined with multiple-scale method, we analytically study the linear absorption and the nonlinear dynamical properties in a lifetime broadened Λ-type three-level self-assembled quantum dots. It is found that this system can exhibit the transparency, and the width of the transparency window becomes wider with the increase of control light field. Interestingly, a weak probe light beam can form spatial weak-light dark solitons. When it propagates along the axial direction, the soliton will transform into a steady spatial weak-light ring dark soltion. In addition, the stability of two-dimensional spatial optical solitons is testified numerically.展开更多
We used multibody dissipative particle dynamics method,by which the attractive and repulsive interactions can be effectively considered,to investigate the evaporation-induced morphology patterns of triblock copolymer ...We used multibody dissipative particle dynamics method,by which the attractive and repulsive interactions can be effectively considered,to investigate the evaporation-induced morphology patterns of triblock copolymer A5B10C5 in thin film.With changing attractive interactions between solvent vapor and triblock copolymer that represent various selective solvents,lamellar morphology,sandwich lamellar morphology,spherical morphology and disorder morphology patterns of the thin films were obtained for both coil-coil-coil and rod-coil-coil chain architectures,respectively.The order parameter and the film thickness were calculated during the process for characterizing the film properties,and it was found that the rigid A-block of the triblock copolymer hinders the formation of an ordered structure.展开更多
Highly photoactive bi-phase nanocrystalline TiO2 photocatalyst was prepared by a solvent evaporation-induced crystallization (SEIC) method, and calcined at different temperatures. The obtained TiO2 photocatalyst was c...Highly photoactive bi-phase nanocrystalline TiO2 photocatalyst was prepared by a solvent evaporation-induced crystallization (SEIC) method, and calcined at different temperatures. The obtained TiO2 photocatalyst was characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface areas. The photocatalytic activity was evaluated by the photocatalytic oxidation of acetone in air. The results show that solvent evaporation can promote the crystallization and phase transformation of TiO2 at 100℃. When calcination temperatures are below 600℃, the prepared TiO2 powders show bimodal pore size distributions in the mesoporous region. At 700℃, the pore size distributions exhibit monomodal distribution of the inter-aggregated pores due to the collapse of the intra-aggregated pores. At 100℃, the obtained TiO2 photocatalyst by this method shows good photocatalytic activity, and at 400℃, its photocatalytic activity exceeds that of Degussa P25. This may be attributed to the fact that the prepared TiO2 photocatalyst has higher specific surface areas, smaller crystallite size and bimodal pore size distribution.展开更多
We investigate sympathetic cooling fermions 40K by evaporatively cooling bosonic 87Rb atoms in a magnetic trap with microwave and radio frequency induced evaporations in detail. The mixture of bosonic and fermionic at...We investigate sympathetic cooling fermions 40K by evaporatively cooling bosonic 87Rb atoms in a magnetic trap with microwave and radio frequency induced evaporations in detail. The mixture of bosonic and fermionic atoms is prepared in their polarized spin states IF = 9/2, mF = 9/2） for 40K and IF = 2, mF=2〉 for 87Rb, which is trapped in Quadrupole-Ioffe-Configuration trap. Comparing microwave with radio frequency evaporatively cooling bosonic STRb atoms with sympathetically cooling Fermi gas 40K, we find that the presence of rubidium atoms in the [2, 1} Zeeman states, which are generated in the evaporative process, gives rise to a significant loss of 40K due to inelastic collisions. Thus, the rubidium atoms populated in the [2, 1} Zeeman states should be removed in order to effectively perform sympathetically cooling 40K with the evaporatively cooled STRb atoms.展开更多
We propose a new strategy to make an active and stable Ni-based catalyst which can be operated in a wide range of reaction temperatures. The ordered mesoporous alumina(OMA) with confined Ni in the pore wall(Ni-OMA) wa...We propose a new strategy to make an active and stable Ni-based catalyst which can be operated in a wide range of reaction temperatures. The ordered mesoporous alumina(OMA) with confined Ni in the pore wall(Ni-OMA) was prepared via the one-pot evaporation induced self-assembly method. By using the incipient impregnation method, different amounts of free Ni were loaded over Ni-OMA(Ni/NiOMA) at a fixed total NiO content of 15 wt%. Characterization results confirmed the formation of wellstructured Ni-OMA, and the ordered structure was still well preserved even after impregnating NiO at a content of as high as 12 wt%. The catalysts were evaluated for the CO methanation as a model reaction under varied conditions. Importantly, the activity and stability of Ni/Ni-OMA for the titled reaction were significantly regulated by simply changing the ratio of the confined to free Ni. Over the optimum catalyst of NiO(2 wt%)/NiO(13 wt%)-OMA, the high activity at a temperature of as low as 300 ℃ was achieved with the space-time yield of methane over 7.6 g gcat-1 h-1 while a long-term stability for a time-onstream of 400 h was confirmed without an observable deactivation under the conditions of 600 ℃ and an extremely high gas hourly space velocity of 120,000 mL g-1 h-1. The results were well explained as the integrated merits of the free Ni for a high dispersion and the confined Ni in OMA for the anti-sintering property.展开更多
基金Projects(51102026,51272032) supported by the Program for the National Natural Science Foundation of ChinaProject(11A014) supported by the Scientific Research Fund of Hunan Provincial Education DepartmentProject supported by the Aid Program for Science and Technology Innovative Research Team in Higher Educational Instituions of Hunan Province,China
文摘The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission electron microscopy(HR-TEM) and N2 adsorption desorption and adsorption are used to study the effects of the synthesized process condition on the microstructure of the as-synthesized mesoporous Ti O2. The photocatalytic performances of as-synthesized samples are evaluated by the degradation of the formaldehyde under ultraviolet light irradiations. The results demonstrate that the as-synthesized mesoporous Ti O2 are anatase with the uniform size about 20-40 nm. The sample is prepared using cetyltrimethyl ammonium bromide(CTAB) as the template with average pore size distribution of 8.12 nm, specific surface area of 68.47 m2/g and pore volume of 0.213 m L/g. The samples show decomposition of formaldehyde 95.8% under ultraviolet light irradiations for 90 min. These results provide a basic experimental process for preparation mesoporous Ti O2, which will posses a broad prospect in terms of the applications in improving indoor air quality.
基金Project supported by the State Key Basic Research Program (Grant No 2006CB921202)the National Natural Science Foundation of China (Grant No 10334050)
文摘The effects of surface-induced evaporative cooling on an atom chip are investigated. The evolutions of temperature, number and phase-space density of the atom cloud are measured when the atom cloud is brought close to the surface. Rapid decrease of the temperature and number of the atoms is found when the atom-surface distance is 〈 100 ttm. A gain of about a factor of five on the phase-space density is obtained. It is found that the efficiency of the surface-induced evaporative cooling depends on the atom-surface distance and the shape of the evaporative trap. When the atoms are moved very close to the surface, severe heating is observed, which dominates when the holding time is 〉 8 ms. It is important that the surface-induced evaporative cooling offers novel possibilities for the realization of a continuous condensation, where a spatially varying evaporative cooling is required.
基金the Natural Sciences and Engineering Council (NSERC) of Canada for strong and sustained support of his research
文摘Volatile organic solvents were considered to have little influence on the synthesis of mesostructured materials through evaporation-induced self-assembly(EISA),because upon evaporation they leave the sol and hence do not interfere with the self-assembly process.We show here that the choice of solvent is crucial in the synthesis of thin films of phenylene-bridged periodic mesoporous organosilica(benzene PMO).Methanol is found to be a better solvent for the synthesis of thin films,whereas ethanol favors the formation of(HO)3Si-C6H4-Si(OH)3 crystals,the identity and structure of which is established by X-ray diffraction.A ternary reactant composition diagram is designed to visualize the relationship among multiple synthesis experiments and to guide the interpretation of experimental results and optimization of the quality of the periodic mesoporous organosilica film.Our study highlights the importance of solvent choice,a factor often neglected in EISA.We expect it to inspire researchers to explore the effect of solvent in designing the synthesis of mesoporous materials.
文摘Al2O3 films were prepared using electron beam evaporation at room temperature. The samples were irradiated with oxygen plasma under different energy. The variations in average surface defect density and root mean square (RMS) surface roughness were characterized using an optical microscope and an atomic force microscope. Surface average defect density increased after plasma treatment. The RMS surface roughness of the samples decreased from 1.92 nm to 1.26 nm because of surface atom restructuring after oxygen plasma conditioning. A 355 nm laser-induced damage experiment indicated that the as-grown sample with the lowest defect density exhibited a higher laser-induced damage threshold (1.12 J/cm2) than the other treated samples. Laser-induced damage images revealed that defect is one of the key factors that affect laser-induced damage on Al2O3 films.
文摘Volatile organic solvents were considered to have little influence on the synthesis of mesostructured materials through evaporation-induced self-assembly(EISA),because upon evaporation they leave the sol and hence do not interfere with the self-assembly process.We show here that the choice of solvent is crucial in the synthesis of thin films of phenylene-bridged periodic mesoporous organosilica(benzene PMO).Methanol is found to be a better solvent for the synthesis of thin films,whereas ethanol favors the formation of(HO)3Si-C6H4-Si(OH)3 crystals,the identity and structure of which is established by X-ray diffraction.A ternary reactant composition diagram is designed to visualize the relationship among multiple synthesis experiments and to guide the interpretation of experimental results and optimization of the quality of the periodic mesoporous organosilica film.Our study highlights the importance of solvent choice,a factor often neglected in EISA.We expect it to inspire researchers to explore the effect of solvent in designing the synthesis of mesoporous materials.
基金theNationalNaturalScienceFoundationofChina (No .5 0 2 72 0 49)
文摘A novel and efficient methodology for obtaining highly active photocatalyst of bi phase TiO 2 with small particle size and high specific surface area was developed by solvent evaporation induced crystallization (SEIC) method at low temperature. The prepared TiO 2 powder was characterized with X ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface areas. The photocatalytic activity was evaluated by the photocatalytic oxidation of acetone in air. The results showed that the photocatalytic activity of the TiO 2 powder prepared by this method approached that of Degussa P25. This may be attributed to the fact that the prepared TiO 2 powder had larger specific surface areas (265 m 2·g -1 ) and smaller crystallite size (about 5 nm), but relatively low crystallinity, as compared with Degussa P25.
基金Project supported by the Special Funds of the National Natural Science Foundation of China(Grant No.11247313)
文摘By using semiclassical theory combined with multiple-scale method, we analytically study the linear absorption and the nonlinear dynamical properties in a lifetime broadened Λ-type three-level self-assembled quantum dots. It is found that this system can exhibit the transparency, and the width of the transparency window becomes wider with the increase of control light field. Interestingly, a weak probe light beam can form spatial weak-light dark solitons. When it propagates along the axial direction, the soliton will transform into a steady spatial weak-light ring dark soltion. In addition, the stability of two-dimensional spatial optical solitons is testified numerically.
基金Supported by the National Natural Science Foundation of China（Nos.21103064, 21173097, 21073075） and the Basic Re- search Fund of Jilin University, China（Nos.450060481158, 450060491249）.
文摘We used multibody dissipative particle dynamics method,by which the attractive and repulsive interactions can be effectively considered,to investigate the evaporation-induced morphology patterns of triblock copolymer A5B10C5 in thin film.With changing attractive interactions between solvent vapor and triblock copolymer that represent various selective solvents,lamellar morphology,sandwich lamellar morphology,spherical morphology and disorder morphology patterns of the thin films were obtained for both coil-coil-coil and rod-coil-coil chain architectures,respectively.The order parameter and the film thickness were calculated during the process for characterizing the film properties,and it was found that the rigid A-block of the triblock copolymer hinders the formation of an ordered structure.
基金This work was partially supported by theNational Natural Science Foundation of China(Grant Nos.50272049,50072016)the Excellent Young Teachers Program of Ministry of Education and the Project-Sponsored by SRF for ROCS of SEMThis work was also financially supported by a grant from the National Natural Science Foundation of China and Research Grant Council of the Hong Kong Special Administrative Region,China(Grant No.N_CUHK433/00).
文摘Highly photoactive bi-phase nanocrystalline TiO2 photocatalyst was prepared by a solvent evaporation-induced crystallization (SEIC) method, and calcined at different temperatures. The obtained TiO2 photocatalyst was characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface areas. The photocatalytic activity was evaluated by the photocatalytic oxidation of acetone in air. The results show that solvent evaporation can promote the crystallization and phase transformation of TiO2 at 100℃. When calcination temperatures are below 600℃, the prepared TiO2 powders show bimodal pore size distributions in the mesoporous region. At 700℃, the pore size distributions exhibit monomodal distribution of the inter-aggregated pores due to the collapse of the intra-aggregated pores. At 100℃, the obtained TiO2 photocatalyst by this method shows good photocatalytic activity, and at 400℃, its photocatalytic activity exceeds that of Degussa P25. This may be attributed to the fact that the prepared TiO2 photocatalyst has higher specific surface areas, smaller crystallite size and bimodal pore size distribution.
基金Project supported by the National Science Foundation for Distinguished Young Scholars of China(Grant No.10725416)the National Basic Research Program of China(Grant No.2006CB921101 and 2011CB921601)the National Science Foundation NSFC Project for Excellent Research Team,China(Grant No.60821004)
文摘We investigate sympathetic cooling fermions 40K by evaporatively cooling bosonic 87Rb atoms in a magnetic trap with microwave and radio frequency induced evaporations in detail. The mixture of bosonic and fermionic atoms is prepared in their polarized spin states IF = 9/2, mF = 9/2） for 40K and IF = 2, mF=2〉 for 87Rb, which is trapped in Quadrupole-Ioffe-Configuration trap. Comparing microwave with radio frequency evaporatively cooling bosonic STRb atoms with sympathetically cooling Fermi gas 40K, we find that the presence of rubidium atoms in the [2, 1} Zeeman states, which are generated in the evaporative process, gives rise to a significant loss of 40K due to inelastic collisions. Thus, the rubidium atoms populated in the [2, 1} Zeeman states should be removed in order to effectively perform sympathetically cooling 40K with the evaporatively cooled STRb atoms.
基金the National Natural Science Foundation of China(U1862116)the National Key Research and Development Program of China(2018YFB0604600-04)the Fundamental Research Funds for the Central Universities(GK201901001)。
文摘We propose a new strategy to make an active and stable Ni-based catalyst which can be operated in a wide range of reaction temperatures. The ordered mesoporous alumina(OMA) with confined Ni in the pore wall(Ni-OMA) was prepared via the one-pot evaporation induced self-assembly method. By using the incipient impregnation method, different amounts of free Ni were loaded over Ni-OMA(Ni/NiOMA) at a fixed total NiO content of 15 wt%. Characterization results confirmed the formation of wellstructured Ni-OMA, and the ordered structure was still well preserved even after impregnating NiO at a content of as high as 12 wt%. The catalysts were evaluated for the CO methanation as a model reaction under varied conditions. Importantly, the activity and stability of Ni/Ni-OMA for the titled reaction were significantly regulated by simply changing the ratio of the confined to free Ni. Over the optimum catalyst of NiO(2 wt%)/NiO(13 wt%)-OMA, the high activity at a temperature of as low as 300 ℃ was achieved with the space-time yield of methane over 7.6 g gcat-1 h-1 while a long-term stability for a time-onstream of 400 h was confirmed without an observable deactivation under the conditions of 600 ℃ and an extremely high gas hourly space velocity of 120,000 mL g-1 h-1. The results were well explained as the integrated merits of the free Ni for a high dispersion and the confined Ni in OMA for the anti-sintering property.
