The instrumented applied rod casting apparatus (ARCA) was developed to investigate the effects of tensile forces in the hot tearing formation of cast AI-Si alloys. The obtained data of tensile forces/temperature was...The instrumented applied rod casting apparatus (ARCA) was developed to investigate the effects of tensile forces in the hot tearing formation of cast AI-Si alloys. The obtained data of tensile forces/temperature was used to identify hot tearing initiation and propagation and the fracture surface of samples was also investigated. The result shows that the applied tensile forces have a complex effect on load onset for the hot tearing initiation and propagation. During the casting solidification, the tensile forces are gradually increased with the increase of solid fraction. Under the action of tensile forces, there will appear hot tearing and crack propagation on the surface of the sample. When the tensile forces exceed the inherent strength of alloys, there will be fractures on the sample. As for the A356 alloy, the critical fracture stress is about 0.1 MPa. The hot tearing surface morphology shows that the remaining intergranular bridge and liquid films are thick enough to allow the formation of dendrite-tip bumps on the fracture surface.展开更多
A thin layer of TiO2 film was deposited on ITO surface via the liquid phase deposition (LPD) process. The photocurrent and electrochemical impedance spectroscopy (EIS) measurements indicated that the as-prepared L...A thin layer of TiO2 film was deposited on ITO surface via the liquid phase deposition (LPD) process. The photocurrent and electrochemical impedance spectroscopy (EIS) measurements indicated that the as-prepared LPD TiO2/ITO film had an excellent photoelectrochemical performance, which showed a sensitive and rapid response to the UV irradiation. The photogenerated electron-hole pairs could be effectively separated by applying an external bias to the TiO2 film electrode. The LPD TiO2/ITO film was employed to study the photoelectrocatalytic (PEC) degradation of 4-aminoantipyrine. Compared with other techniques, the PEC technique based on such a LPD film electrode had a synergetic effect for 4-aminoantipyrine degradation. When the applied bias potential was+0.8 V and the supporting electrolyte concentration of Na2SO4 was 0.1 mol/L, the highest degradation efficiency within 120 min could reach 95%for 0.1 mmol/L 4-aminoantipyrine solution at pH 2.0.展开更多
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
Polyethersulfone(PES) is widely used as biomaterials due to its thermal stability,mechanical strength,and chemical inertness.Nevertheless,their blood compatibility is still not adequate for hemodialysis and blood puri...Polyethersulfone(PES) is widely used as biomaterials due to its thermal stability,mechanical strength,and chemical inertness.Nevertheless,their blood compatibility is still not adequate for hemodialysis and blood purification.In this study,the sulfonated polyethersulfone(SPES) was synthesized through an electrophilic substitution reaction,and PES/SPES blending membranes were prepared.The characterization of the SPES was studied by FTIR.The water adsorption and water contact angle experiments show that the hydrophilicity of PES/SPES blend membrane was improved as for the sulfonate group existing in the SPES.Moreover,PES/SPES blend membrane could effectively reduce bovine serum albumin adsorption and prolong the blood coagulation time compared with the PES membrane,thereby improving blood compatibility.展开更多
The mycotoxin, patulin (4-hydroxy-4H-furo [3, 2c] pyran-2 [6H]-one), is produced by a number of fungi common to fruit and vegetable-based products, most notably apples. Patulin contamination within apple products po...The mycotoxin, patulin (4-hydroxy-4H-furo [3, 2c] pyran-2 [6H]-one), is produced by a number of fungi common to fruit and vegetable-based products, most notably apples. Patulin contamination within apple products poses a serious health risk to consumers. Studies done on laboratory animals have demonstrated that patulin has a broad spectrum of toxicity, including mutagen city and carcinogenicity. The aim of the experiment was studying influence of selectively acting activated carbon powder--Ercarbon SH (Erbsloh, Germany) which is special produced for lowering HMF (hydroxy methyl furfural), on reduction of patulin content in clear apple juice. Industrial apple row material with some damaged parts was pressed, juice was pasteurized at 95 ℃ during 2 min. After cooling on 55 ℃, enzymatic treated and clarified juice were filtered by 0.45 [am pore sizes membrane filter, Apple clear juice sample was divided for five parts. The samples of apple juice were diluted to 11.5° Brix and contacted with concentrations of 2, 2.5, 3 and 3.5 g/L activated carbon powder for 30 min. After filtration in the experimental samples, putulin was quantitatively determined by HPLC (high performance liquid chromatography with UV) detector at 276 nm. The research revealed that the best results were achieved by treatment with activated carbon in its powder form at concentration of 2.5 g/L with 30 min contact time.展开更多
The influence of the drop-casted nickel boride catalyst loading on glassy carbon electrodes was investigated in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in alkaline glycerol electrooxidation.The c...The influence of the drop-casted nickel boride catalyst loading on glassy carbon electrodes was investigated in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in alkaline glycerol electrooxidation.The continuously operated radial flow cell consisted of a borehole electrode positioned 50μm above an internal reflection element enabling operando FTIR spectroscopy.It is identified as a suitable tool for facile and reproducible screening of electrocatalysts under well-defined conditions,additionally providing access to the selectivities in complex reaction networks such as glycerol oxidation.The fast product identification by ATR-IR spectroscopy was validated by the more time-consuming quantitative HPLC analysis of the pumped electrolyte.High degrees of glycerol conversion were achieved under the applied laminar flow conditions using 0.1 M glycerol and 1 M KOH in water and a flow rate of 5μL min^(–1).Conversion and selectivity were found to depend on the catalyst loading,which determined the catalyst layer thickness and roughness.The highest loading of 210μg cm^(–2)resulted in 73%conversion and a higher formate selectivity of almost 80%,which is ascribed to longer residence times in rougher films favoring readsorption and C–C bond scission.The lowest loading of 13μg cm^(–2)was sufficient to reach 63%conversion,a lower formate selectivity of 60%,and,correspondingly,higher selectivities of C_(2)species such as glycolate amounting to 8%.Thus,only low catalyst loadings resulting in very thin films in the fewμm thickness range are suitable for reliable catalyst screening.展开更多
In this work, we evaluate the properties of solution casted polysulfone (PSf)/sulfonated polyethersulfone (SPES) blend membranes prepared by non-solvent induced phase inversion technique. The morphologies of these...In this work, we evaluate the properties of solution casted polysulfone (PSf)/sulfonated polyethersulfone (SPES) blend membranes prepared by non-solvent induced phase inversion technique. The morphologies of these blend membranes, observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging, indicated a smoother skin layer and an increased number of highly interconnected pores in the sub layer. The efficacy of the prepared membranes was evaluated in terms of porosity, ultrafiltration rate (UFR), molecular weight cut-off (MWCO) and mean pore size. The hydrophilicity of these membranes was in consonance with contact angle values. It was observed that the selectivity and the UFR of the blend membranes were higher when compared to pristine membranes. Furthermore, these blend membranes demonstrated an increase in biocompatibility - prolonged blood clotting time, suppressed platelet adhesion, reduced protein adsorption and lower complement activation. These membranes were also investigated for uremic solute removal. Diffusive permeability of middle molecular weight cytochrome-c revealed an increase from 8 × 10 ^-4 cm·s ^-1 to 18 × 10^-4 cm· s^- and illustrates the possibility that these sulfonated PES/PSf blend membranes can be used to prepare membrane modules for hemodialysis applications.展开更多
Metal-organic framework(MOF) thin films are multilayer materials ranging from nanometers to micrometers in thickness,physically or chemically adhesive to a(functionalized) substrate and,in an ideal case,exhibiting low...Metal-organic framework(MOF) thin films are multilayer materials ranging from nanometers to micrometers in thickness,physically or chemically adhesive to a(functionalized) substrate and,in an ideal case,exhibiting low roughness and high homogeneity.Various innovative approaches have been developed for MOF thin film fabrication.Among these advanced materials,surface-attached metal-organic frameworks(SURMOFs) are an important class of MOF films.SURMOFs,fabricated in a step-by-step liquid phase epitaxial(LPE) fashion by alternating deposition of metal and organic linker precursors on a functionalized substrate,for example,thiolate-based self-assembled monolayers(SAMs),have already exhibited their utility in both research and potential applications.SURMOFs combine surface science and the chemistry of MOFs,possessing the following unique advantages that cannot be accessed through other methods:(i) precisely controlling thickness,roughness and homogeneity as well as growth orientation,(ii) studying of MOF growth mechanism,(iii) modifying/tailoring MOFs' structures during the SURMOF growth and thus creating customizable properties,and(iv) existing in the form of thin film/membrane for direct applications,for example,as sensors.This review discusses the oriented and crystalline SURMOFs fabricated by LPE approach,covering their preparation,growth mechanism,and characterization methodology as well as applications based upon the most newly updated knowledge.展开更多
The stability of the thin liquid film in a capillary is important to the phase-change heat transfer process in miniature or micro structures. From the basic equations for motion and heat transfer at the interface of t...The stability of the thin liquid film in a capillary is important to the phase-change heat transfer process in miniature or micro structures. From the basic equations for motion and heat transfer at the interface of the film, its stability is theoretically studied. With evaluation of the effects and relative magnitudes of various driving forces and with the use of long-wave theory in addition to linear stability analysis, the controlling equations are simplified and an evolution equation for the film’s thickness is obtained. Detailed analysis on the evolution equation shows that instability occurs first in the meniscus region and the instability condition varies with boundary conditions, geometrical scales and thermal properties. The numerical results ape well with earlier ones with some favorable extensions and improvements.展开更多
A new approach for exploring effects of interfaces on polar liquids is presented. Their impact on the polar liquid film motor(PLFM) – a novel micro-fluidic device – is studied. We account for the interface's imp...A new approach for exploring effects of interfaces on polar liquids is presented. Their impact on the polar liquid film motor(PLFM) – a novel micro-fluidic device – is studied. We account for the interface's impact by modeling slip boundary effects on the PLFM's electro-hydro-dynamical rotations. Our analytical results show as k = l_s/R increases(with ls denoting the slip length resulting from the interface's impact on the film's properties, k >-1 and R denoting the film's radius):(a) PLFMs subsequently exhibit rotation characteristics under "negative-", "no-", "partial-" and"perfect-" slip boundary conditions;(b) The maximum value of the linear velocity of the steady rotating film increases linearly and its location approaches the film's border;(c) The decay of the angular velocities' dependency on the distance from the center of the film slows down, resulting in a macroscopic flow near the boundary. With our calculated rotation speed distributions consistent with the existing experimental ones, research aiming at fitting computed to measured distributions promises identifying the factors affecting ls, e.g., solid-fluid potential interactions and surface roughness.The consistency also is advantageous for optimizing PLFM's applications as micro-washers, centrifuges, mixers in the lab-on-a-chip.展开更多
The authors consider the homogenization of a class of nonlinear variational inequalities,which include rapid oscillations with respect to a parameter.The homogenization of the corresponding class of differential equat...The authors consider the homogenization of a class of nonlinear variational inequalities,which include rapid oscillations with respect to a parameter.The homogenization of the corresponding class of differential equations is also studied.The results are applied to some models for the pressure in a thin fluid film fluid between two surfaces which are in relative motion.This is an important problem in the lubrication theory.In particular,the analysis includes the effects of surface roughness on both faces and the phenomenon of cavitation.Moreover,the fluid can be modeled as Newtonian or non-Newtonian by using a Rabinowitsch fluid model.展开更多
基金Project(2011ZX04001-031)supported by National Science and Technology Major Project of"High-end CNC Machine Tools and Basic Manufacturing Equipment",ChinaProject(51371109)supported by the National Natural Science Foundation of China
文摘The instrumented applied rod casting apparatus (ARCA) was developed to investigate the effects of tensile forces in the hot tearing formation of cast AI-Si alloys. The obtained data of tensile forces/temperature was used to identify hot tearing initiation and propagation and the fracture surface of samples was also investigated. The result shows that the applied tensile forces have a complex effect on load onset for the hot tearing initiation and propagation. During the casting solidification, the tensile forces are gradually increased with the increase of solid fraction. Under the action of tensile forces, there will appear hot tearing and crack propagation on the surface of the sample. When the tensile forces exceed the inherent strength of alloys, there will be fractures on the sample. As for the A356 alloy, the critical fracture stress is about 0.1 MPa. The hot tearing surface morphology shows that the remaining intergranular bridge and liquid films are thick enough to allow the formation of dendrite-tip bumps on the fracture surface.
基金Projects(12JJ3013,11JJ5010,10JJ5002)supported by the Natural Science Foundation of Hunan Province,ChinaProject(2013CL04)supported by the Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation,Changsha University of Science and Technology,ChinaProject(2011RS4069)supported by the Planned Science and Technology Program of Hunan Province,China
文摘A thin layer of TiO2 film was deposited on ITO surface via the liquid phase deposition (LPD) process. The photocurrent and electrochemical impedance spectroscopy (EIS) measurements indicated that the as-prepared LPD TiO2/ITO film had an excellent photoelectrochemical performance, which showed a sensitive and rapid response to the UV irradiation. The photogenerated electron-hole pairs could be effectively separated by applying an external bias to the TiO2 film electrode. The LPD TiO2/ITO film was employed to study the photoelectrocatalytic (PEC) degradation of 4-aminoantipyrine. Compared with other techniques, the PEC technique based on such a LPD film electrode had a synergetic effect for 4-aminoantipyrine degradation. When the applied bias potential was+0.8 V and the supporting electrolyte concentration of Na2SO4 was 0.1 mol/L, the highest degradation efficiency within 120 min could reach 95%for 0.1 mmol/L 4-aminoantipyrine solution at pH 2.0.
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Supported by the Special Fund for International Cooperation Projects of China (2005DFA50160)
文摘Polyethersulfone(PES) is widely used as biomaterials due to its thermal stability,mechanical strength,and chemical inertness.Nevertheless,their blood compatibility is still not adequate for hemodialysis and blood purification.In this study,the sulfonated polyethersulfone(SPES) was synthesized through an electrophilic substitution reaction,and PES/SPES blending membranes were prepared.The characterization of the SPES was studied by FTIR.The water adsorption and water contact angle experiments show that the hydrophilicity of PES/SPES blend membrane was improved as for the sulfonate group existing in the SPES.Moreover,PES/SPES blend membrane could effectively reduce bovine serum albumin adsorption and prolong the blood coagulation time compared with the PES membrane,thereby improving blood compatibility.
文摘The mycotoxin, patulin (4-hydroxy-4H-furo [3, 2c] pyran-2 [6H]-one), is produced by a number of fungi common to fruit and vegetable-based products, most notably apples. Patulin contamination within apple products poses a serious health risk to consumers. Studies done on laboratory animals have demonstrated that patulin has a broad spectrum of toxicity, including mutagen city and carcinogenicity. The aim of the experiment was studying influence of selectively acting activated carbon powder--Ercarbon SH (Erbsloh, Germany) which is special produced for lowering HMF (hydroxy methyl furfural), on reduction of patulin content in clear apple juice. Industrial apple row material with some damaged parts was pressed, juice was pasteurized at 95 ℃ during 2 min. After cooling on 55 ℃, enzymatic treated and clarified juice were filtered by 0.45 [am pore sizes membrane filter, Apple clear juice sample was divided for five parts. The samples of apple juice were diluted to 11.5° Brix and contacted with concentrations of 2, 2.5, 3 and 3.5 g/L activated carbon powder for 30 min. After filtration in the experimental samples, putulin was quantitatively determined by HPLC (high performance liquid chromatography with UV) detector at 276 nm. The research revealed that the best results were achieved by treatment with activated carbon in its powder form at concentration of 2.5 g/L with 30 min contact time.
文摘The influence of the drop-casted nickel boride catalyst loading on glassy carbon electrodes was investigated in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in alkaline glycerol electrooxidation.The continuously operated radial flow cell consisted of a borehole electrode positioned 50μm above an internal reflection element enabling operando FTIR spectroscopy.It is identified as a suitable tool for facile and reproducible screening of electrocatalysts under well-defined conditions,additionally providing access to the selectivities in complex reaction networks such as glycerol oxidation.The fast product identification by ATR-IR spectroscopy was validated by the more time-consuming quantitative HPLC analysis of the pumped electrolyte.High degrees of glycerol conversion were achieved under the applied laminar flow conditions using 0.1 M glycerol and 1 M KOH in water and a flow rate of 5μL min^(–1).Conversion and selectivity were found to depend on the catalyst loading,which determined the catalyst layer thickness and roughness.The highest loading of 210μg cm^(–2)resulted in 73%conversion and a higher formate selectivity of almost 80%,which is ascribed to longer residence times in rougher films favoring readsorption and C–C bond scission.The lowest loading of 13μg cm^(–2)was sufficient to reach 63%conversion,a lower formate selectivity of 60%,and,correspondingly,higher selectivities of C_(2)species such as glycolate amounting to 8%.Thus,only low catalyst loadings resulting in very thin films in the fewμm thickness range are suitable for reliable catalyst screening.
基金supported by the Department of Science and Technology (DST),Government of India (IDP/MED/2010/17/2(General)
文摘In this work, we evaluate the properties of solution casted polysulfone (PSf)/sulfonated polyethersulfone (SPES) blend membranes prepared by non-solvent induced phase inversion technique. The morphologies of these blend membranes, observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging, indicated a smoother skin layer and an increased number of highly interconnected pores in the sub layer. The efficacy of the prepared membranes was evaluated in terms of porosity, ultrafiltration rate (UFR), molecular weight cut-off (MWCO) and mean pore size. The hydrophilicity of these membranes was in consonance with contact angle values. It was observed that the selectivity and the UFR of the blend membranes were higher when compared to pristine membranes. Furthermore, these blend membranes demonstrated an increase in biocompatibility - prolonged blood clotting time, suppressed platelet adhesion, reduced protein adsorption and lower complement activation. These membranes were also investigated for uremic solute removal. Diffusive permeability of middle molecular weight cytochrome-c revealed an increase from 8 × 10 ^-4 cm·s ^-1 to 18 × 10^-4 cm· s^- and illustrates the possibility that these sulfonated PES/PSf blend membranes can be used to prepare membrane modules for hemodialysis applications.
基金the European Union for funding the research projects on MOF thin films (Priority Program 1362 of the DFG)SUR-MOFs(6th FP, NMP4-CT-2006-032109)
文摘Metal-organic framework(MOF) thin films are multilayer materials ranging from nanometers to micrometers in thickness,physically or chemically adhesive to a(functionalized) substrate and,in an ideal case,exhibiting low roughness and high homogeneity.Various innovative approaches have been developed for MOF thin film fabrication.Among these advanced materials,surface-attached metal-organic frameworks(SURMOFs) are an important class of MOF films.SURMOFs,fabricated in a step-by-step liquid phase epitaxial(LPE) fashion by alternating deposition of metal and organic linker precursors on a functionalized substrate,for example,thiolate-based self-assembled monolayers(SAMs),have already exhibited their utility in both research and potential applications.SURMOFs combine surface science and the chemistry of MOFs,possessing the following unique advantages that cannot be accessed through other methods:(i) precisely controlling thickness,roughness and homogeneity as well as growth orientation,(ii) studying of MOF growth mechanism,(iii) modifying/tailoring MOFs' structures during the SURMOF growth and thus creating customizable properties,and(iv) existing in the form of thin film/membrane for direct applications,for example,as sensors.This review discusses the oriented and crystalline SURMOFs fabricated by LPE approach,covering their preparation,growth mechanism,and characterization methodology as well as applications based upon the most newly updated knowledge.
文摘The stability of the thin liquid film in a capillary is important to the phase-change heat transfer process in miniature or micro structures. From the basic equations for motion and heat transfer at the interface of the film, its stability is theoretically studied. With evaluation of the effects and relative magnitudes of various driving forces and with the use of long-wave theory in addition to linear stability analysis, the controlling equations are simplified and an evolution equation for the film’s thickness is obtained. Detailed analysis on the evolution equation shows that instability occurs first in the meniscus region and the instability condition varies with boundary conditions, geometrical scales and thermal properties. The numerical results ape well with earlier ones with some favorable extensions and improvements.
基金Supported by National Natural Science Foundation of China under Grant Nos.11302118,11275112Natural Science Foundation of Shandong Province under Grant No.ZR2013AQ015
文摘A new approach for exploring effects of interfaces on polar liquids is presented. Their impact on the polar liquid film motor(PLFM) – a novel micro-fluidic device – is studied. We account for the interface's impact by modeling slip boundary effects on the PLFM's electro-hydro-dynamical rotations. Our analytical results show as k = l_s/R increases(with ls denoting the slip length resulting from the interface's impact on the film's properties, k >-1 and R denoting the film's radius):(a) PLFMs subsequently exhibit rotation characteristics under "negative-", "no-", "partial-" and"perfect-" slip boundary conditions;(b) The maximum value of the linear velocity of the steady rotating film increases linearly and its location approaches the film's border;(c) The decay of the angular velocities' dependency on the distance from the center of the film slows down, resulting in a macroscopic flow near the boundary. With our calculated rotation speed distributions consistent with the existing experimental ones, research aiming at fitting computed to measured distributions promises identifying the factors affecting ls, e.g., solid-fluid potential interactions and surface roughness.The consistency also is advantageous for optimizing PLFM's applications as micro-washers, centrifuges, mixers in the lab-on-a-chip.
文摘The authors consider the homogenization of a class of nonlinear variational inequalities,which include rapid oscillations with respect to a parameter.The homogenization of the corresponding class of differential equations is also studied.The results are applied to some models for the pressure in a thin fluid film fluid between two surfaces which are in relative motion.This is an important problem in the lubrication theory.In particular,the analysis includes the effects of surface roughness on both faces and the phenomenon of cavitation.Moreover,the fluid can be modeled as Newtonian or non-Newtonian by using a Rabinowitsch fluid model.