Structured packing is a good candidate for CO2 capture process because of its higher mass transfer efficiency and lower pressure drop. Now, the challenging problem of CO2 capture and storage demands more and more effi...Structured packing is a good candidate for CO2 capture process because of its higher mass transfer efficiency and lower pressure drop. Now, the challenging problem of CO2 capture and storage demands more and more efficiency equipment. The aim of the present study is to investigate the liquid film characteristics under counter current gas phase and throw some insight into the enhancing mechanism of mass transfer performance in structured packing. A high speed digital camera, non-intrusive measurement technique, was used. Water and air were working fluids. Experiments were carried out for different gas/liquid flow rates and different inclination angles. The time-average and instantaneous film widths for each set of flow parameters were calculated. It is shown that the effects of gas phase could be neglected for lower flow rate, and then, become more pronounced at higher flow rate. According to instantaneous film width, three different stages can be distinguished. One is the constant width of liquid film. The second is the slight decrease of film width and the smooth surface. This kind of character will lead to less interfacial area and deteriorate the packing mass transfer performance. For the third stage, the variation of film width shows clearly chaotic behavior. The prediction model was also developed in present work. The predicted and experimental results are in good agreement.展开更多
Interface characteristics possess very important influence on the performance of thin film devices. ITO/ PTCDA/p-Si thin film device was set up with vacuum evaporation and sputter deposition method. The surface and in...Interface characteristics possess very important influence on the performance of thin film devices. ITO/ PTCDA/p-Si thin film device was set up with vacuum evaporation and sputter deposition method. The surface and interface electron states of ITO/PTCDA/p-Si were investigated by X-ray photoelectron spectroscopy （XPS） and argon ion beam etch techniques. Results indicate that at the interface of ITO/PTODA/p- Si,not only ITO/PTCDA-Si but also PDCDA-Si can produce diffusion. Moreover, the XPS spectra of each atom appear chemical shifts, and the chemical shifts of C1s and O1s are more remarkable.展开更多
The main phase transition temperature of a lipid membrane, which is vital for its biomedical applications such as controllable drug release, can be regulated by encapsulating hydrophobic nanoparticles into the membran...The main phase transition temperature of a lipid membrane, which is vital for its biomedical applications such as controllable drug release, can be regulated by encapsulating hydrophobic nanoparticles into the membrane. However, the exact relationship between surface properties of the encapsulating nanoparticles and the main phase transition temperature of a lipid membrane is far from clear. In the present work we performed coarse-grained molecular dynamics simulations to meet this end. The results show the surface roughness of nanoparticles and the density of surface-modifying molecules on the nanoparticles are responsible for the regulation. Increasing the surface roughness of the nanoparticles increases the main phase transition temperature of the lipid membrane, whereas it can be decreased in a nonlinear way via increasing the density of surface-modifying molecules on the nanoparticles. The results may provide insights for understanding recent experimental studies and promote the applications of nanoparticles in controllable drug release by regulating the main phase transition temperature of lipid vesicles.展开更多
Surface eigenstress and eigendisplacement models were used to investigate the surface stress, surface relaxation and surface elasticity of thin films with different surface orientations. Molecular dynamics simulations...Surface eigenstress and eigendisplacement models were used to investigate the surface stress, surface relaxation and surface elasticity of thin films with different surface orientations. Molecular dynamics simulations and first-principles calculations were conducted on face-centered cubic Au films with the focus on relaxation induced nonlinear initial deformation. The simu- lation results verify the theoretical predictions of the size dependency of surface energy density and surface stress, and the non- linear scaling law of the size-dependent Young＇s modulus of thin films. The mechanism of the size-dependent behaviors was further explored at the atomic bonding level with the charge density field. The Au atomic bonding at surfaces is enhanced compared to its interior counterpart and therefore the nominal Young＇s modulus of the Au thin films is larger when the film thickness is smaller.surface elasticity,展开更多
基金Supported by the National Natural Science Foundation of China （20070003154）, the National High Technology Research and Development Program of China （2006AA05Z316, 2006AA030202）, the Specialized Research Fund for Doctoral Program of Higher Education of China （20070003154）, and the Key Program for International Cooperation of Science and Technology, China （2001CB711203）.
文摘Structured packing is a good candidate for CO2 capture process because of its higher mass transfer efficiency and lower pressure drop. Now, the challenging problem of CO2 capture and storage demands more and more efficiency equipment. The aim of the present study is to investigate the liquid film characteristics under counter current gas phase and throw some insight into the enhancing mechanism of mass transfer performance in structured packing. A high speed digital camera, non-intrusive measurement technique, was used. Water and air were working fluids. Experiments were carried out for different gas/liquid flow rates and different inclination angles. The time-average and instantaneous film widths for each set of flow parameters were calculated. It is shown that the effects of gas phase could be neglected for lower flow rate, and then, become more pronounced at higher flow rate. According to instantaneous film width, three different stages can be distinguished. One is the constant width of liquid film. The second is the slight decrease of film width and the smooth surface. This kind of character will lead to less interfacial area and deteriorate the packing mass transfer performance. For the third stage, the variation of film width shows clearly chaotic behavior. The prediction model was also developed in present work. The predicted and experimental results are in good agreement.
基金Project is supported by the National Natural Science Foundationof China (Grant No 60076023)
文摘Interface characteristics possess very important influence on the performance of thin film devices. ITO/ PTCDA/p-Si thin film device was set up with vacuum evaporation and sputter deposition method. The surface and interface electron states of ITO/PTCDA/p-Si were investigated by X-ray photoelectron spectroscopy （XPS） and argon ion beam etch techniques. Results indicate that at the interface of ITO/PTODA/p- Si,not only ITO/PTCDA-Si but also PDCDA-Si can produce diffusion. Moreover, the XPS spectra of each atom appear chemical shifts, and the chemical shifts of C1s and O1s are more remarkable.
文摘The main phase transition temperature of a lipid membrane, which is vital for its biomedical applications such as controllable drug release, can be regulated by encapsulating hydrophobic nanoparticles into the membrane. However, the exact relationship between surface properties of the encapsulating nanoparticles and the main phase transition temperature of a lipid membrane is far from clear. In the present work we performed coarse-grained molecular dynamics simulations to meet this end. The results show the surface roughness of nanoparticles and the density of surface-modifying molecules on the nanoparticles are responsible for the regulation. Increasing the surface roughness of the nanoparticles increases the main phase transition temperature of the lipid membrane, whereas it can be decreased in a nonlinear way via increasing the density of surface-modifying molecules on the nanoparticles. The results may provide insights for understanding recent experimental studies and promote the applications of nanoparticles in controllable drug release by regulating the main phase transition temperature of lipid vesicles.
基金supported by the Hong Kong Research Grants Council(Grant No.622312)
文摘Surface eigenstress and eigendisplacement models were used to investigate the surface stress, surface relaxation and surface elasticity of thin films with different surface orientations. Molecular dynamics simulations and first-principles calculations were conducted on face-centered cubic Au films with the focus on relaxation induced nonlinear initial deformation. The simu- lation results verify the theoretical predictions of the size dependency of surface energy density and surface stress, and the non- linear scaling law of the size-dependent Young＇s modulus of thin films. The mechanism of the size-dependent behaviors was further explored at the atomic bonding level with the charge density field. The Au atomic bonding at surfaces is enhanced compared to its interior counterpart and therefore the nominal Young＇s modulus of the Au thin films is larger when the film thickness is smaller.surface elasticity,
