Based on A356 aluminum alloy,aluminum foams were prepared by gas injection foaming process with pure nitrogen,air and some gas mixtures.The oxygen volume fraction of these gas mixtures varied from 0.2%to 8.0%.Optical ...Based on A356 aluminum alloy,aluminum foams were prepared by gas injection foaming process with pure nitrogen,air and some gas mixtures.The oxygen volume fraction of these gas mixtures varied from 0.2%to 8.0%.Optical microscopy,scanning electron microscopy(SEM) and Auger electron spectroscopy(AES) were used to analyze the influence of oxygen content on cell structure,relative density,macro and micro morphology of cell walls,coverage area fraction of oxide film,thickness of oxide film and other aspects.Results indicate that the coverage area fraction of oxide film on bubble surface increases with the increase of oxygen content when the oxygen volume is less than 1.2%.While when the oxygen volume fraction is larger than 1.6%,an oxide film covers the entire bubble surface and aluminum foams with good cell structure can be produced.The thicknesses of oxide films of aluminum foams produced by gas mixtures containing 1.6%-21%oxygen are almost the same.The reasons why the thickness of oxide film nearly does not change with the variation of oxygen content and the amount of oxygen needed to achieve 100%coverage of oxide film are both discussed.In addition,the role of oxide film on bubble surface in foam stability is also analyzed.展开更多
To evaluate the effect of proteolytic enzymes on the absorption of insulin in the buccal mucosa, the trichloroacetic acid (TCA) method was used to estimate the degradation of insulin under different conditions in the ...To evaluate the effect of proteolytic enzymes on the absorption of insulin in the buccal mucosa, the trichloroacetic acid (TCA) method was used to estimate the degradation of insulin under different conditions in the buccal mucosal homogenates. In vivo experiments estimating the enhancement of hypoglycaemic effect by enzyme inhibitors were also conducted. The results showed that proteolytic enzymes in the buccal mucosa were less active than in the intestine. Bacitracin, aprotinin and sodium deoxycholate could inhibit the degradation of insulin in the buccal mucosal homogenates. The degradation of insulin in buccal mucosal homogenates of normal hamsters was smaller than that of diabetic hamsters. In vivo experiments of hypoglycaemia supported the in vitro results. When given buccally, bacitracin, aprotinin and sodium deoxycholate could increase the relative pharmacological bioavailability of insulin. When co-administered with aprotinin(0.1%), bacitracin(0.5%) and sodium deoxycholate(5%), the relative pharmacological bioavailabilities of insulin were 4.84%, 6.60% and 14.95% respectively. The in vitro and in vivo results suggest that proteolytic enzymes are present in the buccal mucosa, which limit absorption of insulin. Co-administration with some enzyme inhibitors can improve the bioavailability of insulin via buccal delivery and sodium deoxycholte is more efficient than some enzyme inhibitors used for improving buccal absorption.展开更多
Ceramic capillary membrane has received much attention due to its relatively high pack density and favorable mechanical strength.However,it is difficult to prepare capillary membrane on its thin support by a dip-coati...Ceramic capillary membrane has received much attention due to its relatively high pack density and favorable mechanical strength.However,it is difficult to prepare capillary membrane on its thin support by a dip-coating method.In this study,alumina microfiltration membranes were prepared on the inner surface of alumina capillary support(outer diameter 4 mm,inner diameter 2.5 mm)by a dip-coating method.Scanning electron microscopy(SEM)observation,gas bubble pressure(GBP)method and membrane permeation test were carried out to evaluate membrane performance.Two major effects in preparation of crack-free membrane,capillary filtration and film-coating,upon the thin support were studied.The as-prepared crack-free membrane presents a narrow pore size distribution,a mean pore size of about 0.6μm and a high pure water flux of 86000 L·m -2 ·h -1 ·MPa.It is proved that the membrane thickness should be sufficiently large to overcome the defects of support surface,but it is only one of the prerequisites for the formation of crack-free membrane.Furthermore,it is demonstrated that the capillary filtration effect is greatly restricted for thin capillary support with the dip-coating method and the film-coating effect plays a crucial role in the formation of crack-free membrane.展开更多
Dense membrane with the composition of SrFe0.6Cu0.3Ti0.1O3-δ (SFCTO) was prepared by solid state reaction method. Oxygen permeation flux through this membrane was investigated at operating temperature ranging from ...Dense membrane with the composition of SrFe0.6Cu0.3Ti0.1O3-δ (SFCTO) was prepared by solid state reaction method. Oxygen permeation flux through this membrane was investigated at operating temperature ranging from 750℃ to 950℃ and different oxygen partial pressure. XRD measurements indicated that the compound was able to form single-phased perovskite structure in which part of Fe was replaced by Cu and Ti. The oxygen desorption and the reducibility of SFCTO powder were characterized by thermogravimetric analysis and temperature programmed reduction analysis, respectively. It was found that SFCTO had good structure stability under low oxygen pressure at high temperature. The addition of Ti increased the reduction temperature of Cu and Fe. Performance tests showed that the oxygen permeation flux through a 1.5 mm thick SFCTO membrane was 0.35-0.96 ml·min ^-1·cm^-2 under air/helium oxygen partial pressure gradient with activation energy of 53.2 kJ·mol^-1. The methane conversion of 85%, CO selectivity of 90% and comparatively higher oxygen permeation flux of 5 ml·min^-1·cm^- 2 were achieved at 850℃, when a SFCTO membrane reactor loaded with Ni-Ce/Al2O3 catalyst was applied for the partial oxidation of methane to syngas.展开更多
Microbial cellulose (MC) membranes produced by Acetobacter xylinum NUST4.1,were used as flexible substrates for the fabrication of transparent indium tin oxide (ITO) electrodes.Transparent and conductive ITO thin ...Microbial cellulose (MC) membranes produced by Acetobacter xylinum NUST4.1,were used as flexible substrates for the fabrication of transparent indium tin oxide (ITO) electrodes.Transparent and conductive ITO thin films were deposited on MC membrane at room temperature using radio frequency (RF) magnetron sputtering.The optimum ITO deposition conditions were achieved by examining crystalline structure,surface morphology and op-toelectrical characteristics with X-ray diffraction (XRD),scanning electron microscopy (SEM),atomic force mi-croscopy (AFM),and UV spectroscopy.The sheet resistance of the samples was measured with a four-point probe and the resistivity of the film was calculated.The results reveal that the preferred orientation of the deposited ITO crystals is strongly dependent upon with oxygen content (O2/Ar,volume ratio) in the sputtering chamber.And the ITO crystalline structure directly determines the conductivity of ITO-deposited films.High conductive [sheet resis-tance ~120 Ω·square-1 (Ω·sq-1)] and transparent (above 76%) ITO thin films (240 nm thick) were obtained with a moderate sputtering power (about 60 W) and with an oxygen flow rate of 0.25 ml·min-1 (sccm) during the deposi-tion.These results show that the ITO-MC electrodes can find their potential application in optoelectrical devices.展开更多
A microporous zirconia membrane with hydrogen permeance about 5 × 10-8mol·m-2·s-1·Pa-1, H2/CO2 permselectivity of ca. 14, and excellent hydrothermal stability under steam pressure of 100 k Pa was f...A microporous zirconia membrane with hydrogen permeance about 5 × 10-8mol·m-2·s-1·Pa-1, H2/CO2 permselectivity of ca. 14, and excellent hydrothermal stability under steam pressure of 100 k Pa was fabricated via polymeric sol–gel process. The effect of calcination temperature on single gas permeance of sol–gel derived zirconia membranes was investigated. Zirconia membranes calcined at 350 °C and 400 °C showed similar single gas permeance, with permselectivities of hydrogen towards other gases, such as oxygen, nitrogen, methane, and sulfur hexa fluoride, around Knudsen values. A much lower CO2permeance(3.7 × 10-9mol·m-2·s-1·Pa-1)was observed due to the interaction between CO2 molecules and pore wall of membrane. Higher calcination temperature, 500 °C, led to the formation of mesoporous structure and, hence, the membrane lost its molecular sieving property towards hydrogen and carbon dioxide. The stability of zirconia membrane in the presence of hot steam was also investigated. Exposed to 100 k Pa steam for 400 h, the membrane performance kept unchanged in comparison with freshly prepared one, with hydrogen and carbon dioxide permeances of 4.7 × 10-8and ~ 3 × 10-9mol·m-2·s-1·Pa-1, respectively. Both H2 and CO2permeances of the zirconia membrane decreased with exposure time to 100 k Pa steam. With a total exposure time of 1250 h, the membrane presented hydrogen permeance of 2.4 × 10-8mol·m-2·s-1·Pa-1and H2/CO2 permselectivity of 28, indicating that the membrane retains its microporous structure.展开更多
IrO2-TiO2 thin films were prepared by atomic layer deposition using Ir(EtCp)(COD) and titanium isopropoxide (TTIP). The resistivity of IrO2-TiO2 thin films can be easily controlled from 1 500 to 356.7 μΩ·...IrO2-TiO2 thin films were prepared by atomic layer deposition using Ir(EtCp)(COD) and titanium isopropoxide (TTIP). The resistivity of IrO2-TiO2 thin films can be easily controlled from 1 500 to 356.7 μΩ·cm by the IrO2 intermixing ratio from 0.55 to 0.78 in the IrO2-TiO2 thin films. The low temperature coefficient of resistance(TCR) values can be obtained by adopting IrO2-TiO2 composite thin films. Moreover, the change in the resistivity of IrO2-TiO2 thin films was below 10% even after O2 annealing process at 600 ℃. The step stress test results show that IrO2-TiO2 films have better characteristics than conventional TaN08 heater resistor. Therefore, IrO2-TiO2 composite thin films can be used as a heater resistor material in thermal inkjet printhead.展开更多
Yttrium iron garnet (YIG) is widely used for microwave ferrite devices, especially for optical isolators. In this paper, ferrite ceramic target using cerium (Ce)-substituted YIG was made using ferric oxide (Fe203...Yttrium iron garnet (YIG) is widely used for microwave ferrite devices, especially for optical isolators. In this paper, ferrite ceramic target using cerium (Ce)-substituted YIG was made using ferric oxide (Fe203), cerium oxide (CeO2) and yttrium oxide (Y2O3) powders as raw material. Ce: YIG thin films were fabricated by radio frequency (RF) magnetron sputtering. The experimental result showed that the polycrystalline YIG was obtained after sintering at 1 350 ℃ for 6 h, and the polycrystalline Ce: YIG thin films were achieved annealing up to 700 ℃ in the air.展开更多
Low valence vanadium oxide(VO2-x) thin films were prepared on SiO2/Si substrates at room temperature by direct current facing targets reactive magnetron sputtering, and then proc- essed through rapid thermal annealing...Low valence vanadium oxide(VO2-x) thin films were prepared on SiO2/Si substrates at room temperature by direct current facing targets reactive magnetron sputtering, and then proc- essed through rapid thermal annealing. The effects of the annealing on the structure and phase transition property of VO2 were discussed. X-ray photoelectron spectroscopy, X-ray diffraction tech- nique and Fourier transform infrared spectroscopy were employed to study the phase composition and structure of the thin films. The resistance-temperature property was measured. The results show that VO2 thin film is obtained after annealed at 320 ℃ for 3 h, its phase transition tempera- ture is 56 ℃, and the resistance changes by more than 2 orders. The vanadium oxide thin films are applicable in thermochromic smart windows, and the deposition and annealing process is compatible with micro electromechanical system process.展开更多
The oxidative dehydrogenation of butane to butadiene and butene was studied using a conventional fixed-bed ractor (FBR), inert membrane reactor (IMR) and mixed inert membrane reactor (MIMR). When IMR and MIMR were emp...The oxidative dehydrogenation of butane to butadiene and butene was studied using a conventional fixed-bed ractor (FBR), inert membrane reactor (IMR) and mixed inert membrane reactor (MIMR). When IMR and MIMR were employed, a ceramic membrane modified by partially coating with glaze was used to distribute oxygen to a fixed-bed of 24-V-Mg-O catalyst. The oxygen partial pressure in the catalyst bed could be decreased. The effect of feeding modes and operation conditions were investigated. The selectivity of C4 dehydrogenation products (butene and butadiene) was found to be higher in IMR than in FBR. The feeding mode with 20% of air mixing with butane in MIMR was found to be more efficient than the feeding mode with all air permeating through ceramic membrane. The MIMR gave the most smooth temperature profile along the bed.展开更多
The porous anodic alumina membranes (PAAMs) have been successfully used as templates for the fabrication of functional nano-materials due to their outstanding regularity and physicochemical properties. In this paper...The porous anodic alumina membranes (PAAMs) have been successfully used as templates for the fabrication of functional nano-materials due to their outstanding regularity and physicochemical properties. In this paper, a transparent double-sided anodic alumina membrane with ultra-thin aluminum substrate was fabricated with the three-step anodic oxidation method in the oxalic acid electrolyte. The characters such as the top-surface morphology, membrane thickness, and depth of nanopores of this three-layer (A1203-A1-A1203) sandwiched nano-structure were controllable through regulating the main anodic oxidation conditions, e.g., anodic oxidation time of various steps, coating remove process. The experiments data revealed that the aluminum substrate is exponential declined with the oxidation time when it was approximately reduced by a few micrometers. This new double-sided anodic alumina membrane can be used as the high-quality functional field emission materials and templates.展开更多
Tailoring tire pore structure and surface chemistry of graphene-based laminates is essentially important for their applications as separation membranes. Usually, pure graphene oxide (GO) and completely reduced GO (...Tailoring tire pore structure and surface chemistry of graphene-based laminates is essentially important for their applications as separation membranes. Usually, pure graphene oxide (GO) and completely reduced GO (rGO) membranes suffer florn low water permeance because of the lack of pristine graphitic sp2 domains and very small interlayer spacing, respectively. In this work, we studied the influence of reduction degree on the structure and separation pertornrance of rGO membranes, tt was found that weak reduction retains the good dispersion and hydrophilicity of GO nanosheets. More importantly, it increases the number of pristine graphitic sp2 domains in rGO nanosheets while keeping the large interlayer spacing of the GO membranes in most regions at the same time. The resultant mernbranes show a high water permeance of 56.3 L m^-2 h^ -1 bar^ -1, which is about 4 times and over 10^4 times larger tban those of the GO and completely reduced rGO membranes, respectively, and high rejection over 95700 for various dyes. Furthermore, they show better structure stability and more superior separation perfor- mance than GO membranes in acid and alkali environments.展开更多
Leaf cuticle analysis has long been a powerful tool for fossil plant identification, systematics, and palaeoclimatological recon- struction. In recent decades the application of stomatal frequency data that are relied...Leaf cuticle analysis has long been a powerful tool for fossil plant identification, systematics, and palaeoclimatological recon- struction. In recent decades the application of stomatal frequency data that are relied on precise calculation of stomata on plant fossil cuticles to reconstruct ancient atmospheric CO2 concentration made the preparation of cuticular membrane with sufficient size a critical technique in palaeoclimatological research. However, for plants with originally thin and fragile cuticles, e.g., most deciduous plants, conventional techniques sometimes fail to obtain cuticular membranes with sufficient size, or sometimes unable to recover any. This has largely hampered the usage of fossil cuticle analysis in palaeobotanical and palaeo- climatological research. Here, we describe a new method using clear nail polish as a medium to "strengthen" the originally thin and fragile cuticles prior to maceration procedures. We demonstrate the method by using middle Eocene Metasequoia fossils that were notorious for the difficulty of recovering large-sized clean cuticular membranes due to their thin and fragile nature. Metasequoia, with well-documented and widely-distributed fossil records since the Late Cretaceous and with a living repre- sentative, 114. glyptostroboides, as a comparative reference, bas been widely used as a model genus for the study of evolution of plants, palaeoclimatological reconstruction, and plant adaptation to climate changes. But its deciduous habit produces thin cuticles and makes the preparation of clean cuticular membranes a tedious process. The new method successfully allows us to recover its delicate cuticular membranes with sufficient sizes for SEM observation and stomatal frequency analysis.展开更多
A simple and cost-effective method has been developed for the fabrication of microtubular solid oxide fuel cells (MT-SOFCs). Highly asymmetric electrolyte hollow fibers composed of a thin dense skin layer and a thick ...A simple and cost-effective method has been developed for the fabrication of microtubular solid oxide fuel cells (MT-SOFCs). Highly asymmetric electrolyte hollow fibers composed of a thin dense skin layer and a thick porous substrate are first prepared by a modified phase inversion/sintering technique. The porous substrate is then formed into the anode by deposition of a Ni catalyst via an electroless plating method inside the pores while the thin dense skin layer serves directly as the electrolyte film of the fuel cells. A porous cathode layer is produced on the outer surface of the Ni-deposited hollow fibers by slurry coating and subsequent sintering to form a complete micro tubular fuel cell. The process has been employed to fabricate yttrium stabilized zirconia (YSZ) supported Ni-YSZ-YSZ-La0.6Sr0.4Co0.2Fe0.8O3-(LSCF) microtubular fuel cells. The maximum output of the resulting cells is 159.6 mW cm-2 at 800 °C when using H2 as the fuel feed and air as the oxidant.展开更多
In this paper, a partial discharge detection system is proposed using an optical fiber Fabry-Perot(FP) interferometric sensor, which is fabricated by photolithography. SU-8 photoresist is employed due to its low Young...In this paper, a partial discharge detection system is proposed using an optical fiber Fabry-Perot(FP) interferometric sensor, which is fabricated by photolithography. SU-8 photoresist is employed due to its low Young's modulus and potentially high sensitivity for ultrasound detection. The FP cavity is formed by coating the fiber end face with two layers of SU-8 so that the cavity can be controlled by the thickness of the middle layer of SU-8. Static pressure measurement experiments are done to estimate the sensing performance. The results show that the SU-8 based sensor has a sensitivity of 154.8 nm/kP a, which is much higher than that of silica based sensor under the same condition. Moreover, the sensor is demonstrated successfully to detect ultrasound from electrode discharge.展开更多
基金Project(51371104)supported by the National Natural Science Foundation of China
文摘Based on A356 aluminum alloy,aluminum foams were prepared by gas injection foaming process with pure nitrogen,air and some gas mixtures.The oxygen volume fraction of these gas mixtures varied from 0.2%to 8.0%.Optical microscopy,scanning electron microscopy(SEM) and Auger electron spectroscopy(AES) were used to analyze the influence of oxygen content on cell structure,relative density,macro and micro morphology of cell walls,coverage area fraction of oxide film,thickness of oxide film and other aspects.Results indicate that the coverage area fraction of oxide film on bubble surface increases with the increase of oxygen content when the oxygen volume is less than 1.2%.While when the oxygen volume fraction is larger than 1.6%,an oxide film covers the entire bubble surface and aluminum foams with good cell structure can be produced.The thicknesses of oxide films of aluminum foams produced by gas mixtures containing 1.6%-21%oxygen are almost the same.The reasons why the thickness of oxide film nearly does not change with the variation of oxygen content and the amount of oxygen needed to achieve 100%coverage of oxide film are both discussed.In addition,the role of oxide film on bubble surface in foam stability is also analyzed.
文摘To evaluate the effect of proteolytic enzymes on the absorption of insulin in the buccal mucosa, the trichloroacetic acid (TCA) method was used to estimate the degradation of insulin under different conditions in the buccal mucosal homogenates. In vivo experiments estimating the enhancement of hypoglycaemic effect by enzyme inhibitors were also conducted. The results showed that proteolytic enzymes in the buccal mucosa were less active than in the intestine. Bacitracin, aprotinin and sodium deoxycholate could inhibit the degradation of insulin in the buccal mucosal homogenates. The degradation of insulin in buccal mucosal homogenates of normal hamsters was smaller than that of diabetic hamsters. In vivo experiments of hypoglycaemia supported the in vitro results. When given buccally, bacitracin, aprotinin and sodium deoxycholate could increase the relative pharmacological bioavailability of insulin. When co-administered with aprotinin(0.1%), bacitracin(0.5%) and sodium deoxycholate(5%), the relative pharmacological bioavailabilities of insulin were 4.84%, 6.60% and 14.95% respectively. The in vitro and in vivo results suggest that proteolytic enzymes are present in the buccal mucosa, which limit absorption of insulin. Co-administration with some enzyme inhibitors can improve the bioavailability of insulin via buccal delivery and sodium deoxycholte is more efficient than some enzyme inhibitors used for improving buccal absorption.
基金Supported by the National High Technology Research and Development Program of China (2007AA030303), the National Basic Research Program of China (2009CB623400) and the National Natural Science Foundation of China (20776067).
文摘Ceramic capillary membrane has received much attention due to its relatively high pack density and favorable mechanical strength.However,it is difficult to prepare capillary membrane on its thin support by a dip-coating method.In this study,alumina microfiltration membranes were prepared on the inner surface of alumina capillary support(outer diameter 4 mm,inner diameter 2.5 mm)by a dip-coating method.Scanning electron microscopy(SEM)observation,gas bubble pressure(GBP)method and membrane permeation test were carried out to evaluate membrane performance.Two major effects in preparation of crack-free membrane,capillary filtration and film-coating,upon the thin support were studied.The as-prepared crack-free membrane presents a narrow pore size distribution,a mean pore size of about 0.6μm and a high pure water flux of 86000 L·m -2 ·h -1 ·MPa.It is proved that the membrane thickness should be sufficiently large to overcome the defects of support surface,but it is only one of the prerequisites for the formation of crack-free membrane.Furthermore,it is demonstrated that the capillary filtration effect is greatly restricted for thin capillary support with the dip-coating method and the film-coating effect plays a crucial role in the formation of crack-free membrane.
基金Supported by the Natural Science Foundation of Guangdong Province (030514) and the Science and Technology Program of Guangdong Province (2004B33401006).
文摘Dense membrane with the composition of SrFe0.6Cu0.3Ti0.1O3-δ (SFCTO) was prepared by solid state reaction method. Oxygen permeation flux through this membrane was investigated at operating temperature ranging from 750℃ to 950℃ and different oxygen partial pressure. XRD measurements indicated that the compound was able to form single-phased perovskite structure in which part of Fe was replaced by Cu and Ti. The oxygen desorption and the reducibility of SFCTO powder were characterized by thermogravimetric analysis and temperature programmed reduction analysis, respectively. It was found that SFCTO had good structure stability under low oxygen pressure at high temperature. The addition of Ti increased the reduction temperature of Cu and Fe. Performance tests showed that the oxygen permeation flux through a 1.5 mm thick SFCTO membrane was 0.35-0.96 ml·min ^-1·cm^-2 under air/helium oxygen partial pressure gradient with activation energy of 53.2 kJ·mol^-1. The methane conversion of 85%, CO selectivity of 90% and comparatively higher oxygen permeation flux of 5 ml·min^-1·cm^- 2 were achieved at 850℃, when a SFCTO membrane reactor loaded with Ni-Ce/Al2O3 catalyst was applied for the partial oxidation of methane to syngas.
基金Supported by the National Natural Science Foundation of China (10776014) Nanjing University of Science and Technology (NUST) Research Funding
文摘Microbial cellulose (MC) membranes produced by Acetobacter xylinum NUST4.1,were used as flexible substrates for the fabrication of transparent indium tin oxide (ITO) electrodes.Transparent and conductive ITO thin films were deposited on MC membrane at room temperature using radio frequency (RF) magnetron sputtering.The optimum ITO deposition conditions were achieved by examining crystalline structure,surface morphology and op-toelectrical characteristics with X-ray diffraction (XRD),scanning electron microscopy (SEM),atomic force mi-croscopy (AFM),and UV spectroscopy.The sheet resistance of the samples was measured with a four-point probe and the resistivity of the film was calculated.The results reveal that the preferred orientation of the deposited ITO crystals is strongly dependent upon with oxygen content (O2/Ar,volume ratio) in the sputtering chamber.And the ITO crystalline structure directly determines the conductivity of ITO-deposited films.High conductive [sheet resis-tance ~120 Ω·square-1 (Ω·sq-1)] and transparent (above 76%) ITO thin films (240 nm thick) were obtained with a moderate sputtering power (about 60 W) and with an oxygen flow rate of 0.25 ml·min-1 (sccm) during the deposi-tion.These results show that the ITO-MC electrodes can find their potential application in optoelectrical devices.
基金Supported by the National Natural Science Foundation of China(21276123,21490581)the National High Technology Research and Development Program of China(2012AA03A606)+3 种基金State Key Laboratory of Materials-Oriented Chemical Engineering(ZK201002)the Natural Science Research Plan of Jiangsu Universities(11KJB530006)the "Summit of the Six Top Talents" Program of Jiangsu Provincea Project Funded by the Priority Academic Program development of Jiangsu Higher Education Institutions(PAPD)
文摘A microporous zirconia membrane with hydrogen permeance about 5 × 10-8mol·m-2·s-1·Pa-1, H2/CO2 permselectivity of ca. 14, and excellent hydrothermal stability under steam pressure of 100 k Pa was fabricated via polymeric sol–gel process. The effect of calcination temperature on single gas permeance of sol–gel derived zirconia membranes was investigated. Zirconia membranes calcined at 350 °C and 400 °C showed similar single gas permeance, with permselectivities of hydrogen towards other gases, such as oxygen, nitrogen, methane, and sulfur hexa fluoride, around Knudsen values. A much lower CO2permeance(3.7 × 10-9mol·m-2·s-1·Pa-1)was observed due to the interaction between CO2 molecules and pore wall of membrane. Higher calcination temperature, 500 °C, led to the formation of mesoporous structure and, hence, the membrane lost its molecular sieving property towards hydrogen and carbon dioxide. The stability of zirconia membrane in the presence of hot steam was also investigated. Exposed to 100 k Pa steam for 400 h, the membrane performance kept unchanged in comparison with freshly prepared one, with hydrogen and carbon dioxide permeances of 4.7 × 10-8and ~ 3 × 10-9mol·m-2·s-1·Pa-1, respectively. Both H2 and CO2permeances of the zirconia membrane decreased with exposure time to 100 k Pa steam. With a total exposure time of 1250 h, the membrane presented hydrogen permeance of 2.4 × 10-8mol·m-2·s-1·Pa-1and H2/CO2 permselectivity of 28, indicating that the membrane retains its microporous structure.
基金supported by a grant from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy, Republic of Koreasupported by Basic Science Research program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0001-226)
文摘IrO2-TiO2 thin films were prepared by atomic layer deposition using Ir(EtCp)(COD) and titanium isopropoxide (TTIP). The resistivity of IrO2-TiO2 thin films can be easily controlled from 1 500 to 356.7 μΩ·cm by the IrO2 intermixing ratio from 0.55 to 0.78 in the IrO2-TiO2 thin films. The low temperature coefficient of resistance(TCR) values can be obtained by adopting IrO2-TiO2 composite thin films. Moreover, the change in the resistivity of IrO2-TiO2 thin films was below 10% even after O2 annealing process at 600 ℃. The step stress test results show that IrO2-TiO2 films have better characteristics than conventional TaN08 heater resistor. Therefore, IrO2-TiO2 composite thin films can be used as a heater resistor material in thermal inkjet printhead.
基金National Natural Science Foundation of China(NSFC)(No.51175418)Program for New Century Excellent Talents in University(No.93JXDW02000006)+4 种基金Natural Science Foundation of Shaanxi Province(No.2011JQ7004)Fundamental Research Funds for the Central Universities of Xi'an Jiaotong University(No.2011jdgz09No.2011jdhz23No.xjj2011068)Fund of the State Key Laboratory of Digital Manufacturing Equipment & Technology(No.DMETKF2012009)
文摘Yttrium iron garnet (YIG) is widely used for microwave ferrite devices, especially for optical isolators. In this paper, ferrite ceramic target using cerium (Ce)-substituted YIG was made using ferric oxide (Fe203), cerium oxide (CeO2) and yttrium oxide (Y2O3) powders as raw material. Ce: YIG thin films were fabricated by radio frequency (RF) magnetron sputtering. The experimental result showed that the polycrystalline YIG was obtained after sintering at 1 350 ℃ for 6 h, and the polycrystalline Ce: YIG thin films were achieved annealing up to 700 ℃ in the air.
基金Natural Science Foundation of Tianjin(No.043100811)the Key Program of Natural Science Foundation of Tianjin(No.08JCZDJC17500)
文摘Low valence vanadium oxide(VO2-x) thin films were prepared on SiO2/Si substrates at room temperature by direct current facing targets reactive magnetron sputtering, and then proc- essed through rapid thermal annealing. The effects of the annealing on the structure and phase transition property of VO2 were discussed. X-ray photoelectron spectroscopy, X-ray diffraction tech- nique and Fourier transform infrared spectroscopy were employed to study the phase composition and structure of the thin films. The resistance-temperature property was measured. The results show that VO2 thin film is obtained after annealed at 320 ℃ for 3 h, its phase transition tempera- ture is 56 ℃, and the resistance changes by more than 2 orders. The vanadium oxide thin films are applicable in thermochromic smart windows, and the deposition and annealing process is compatible with micro electromechanical system process.
基金Supported by the National Natural Science Foundation of China(No.29776005).
文摘The oxidative dehydrogenation of butane to butadiene and butene was studied using a conventional fixed-bed ractor (FBR), inert membrane reactor (IMR) and mixed inert membrane reactor (MIMR). When IMR and MIMR were employed, a ceramic membrane modified by partially coating with glaze was used to distribute oxygen to a fixed-bed of 24-V-Mg-O catalyst. The oxygen partial pressure in the catalyst bed could be decreased. The effect of feeding modes and operation conditions were investigated. The selectivity of C4 dehydrogenation products (butene and butadiene) was found to be higher in IMR than in FBR. The feeding mode with 20% of air mixing with butane in MIMR was found to be more efficient than the feeding mode with all air permeating through ceramic membrane. The MIMR gave the most smooth temperature profile along the bed.
基金supported by the Major Research Plan of the National Nat-ural Science Foundation of China(Grant No.91123030)the International Cooperation Foundation of the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant No.2011DFA12220)the National Natural Science Foundation of China(Grant No.61378083)
文摘The porous anodic alumina membranes (PAAMs) have been successfully used as templates for the fabrication of functional nano-materials due to their outstanding regularity and physicochemical properties. In this paper, a transparent double-sided anodic alumina membrane with ultra-thin aluminum substrate was fabricated with the three-step anodic oxidation method in the oxalic acid electrolyte. The characters such as the top-surface morphology, membrane thickness, and depth of nanopores of this three-layer (A1203-A1-A1203) sandwiched nano-structure were controllable through regulating the main anodic oxidation conditions, e.g., anodic oxidation time of various steps, coating remove process. The experiments data revealed that the aluminum substrate is exponential declined with the oxidation time when it was approximately reduced by a few micrometers. This new double-sided anodic alumina membrane can be used as the high-quality functional field emission materials and templates.
基金supported by the National Key Research and Development Program of China(2016YFA0200101)the National Natural Science Foundation of China(51325205,51290273,and51521091)Chinese Academy of Sciences(KGZD-EW-303-1,KGZDEW-T06,174321KYSB20160011,and XDPB06)
文摘Tailoring tire pore structure and surface chemistry of graphene-based laminates is essentially important for their applications as separation membranes. Usually, pure graphene oxide (GO) and completely reduced GO (rGO) membranes suffer florn low water permeance because of the lack of pristine graphitic sp2 domains and very small interlayer spacing, respectively. In this work, we studied the influence of reduction degree on the structure and separation pertornrance of rGO membranes, tt was found that weak reduction retains the good dispersion and hydrophilicity of GO nanosheets. More importantly, it increases the number of pristine graphitic sp2 domains in rGO nanosheets while keeping the large interlayer spacing of the GO membranes in most regions at the same time. The resultant mernbranes show a high water permeance of 56.3 L m^-2 h^ -1 bar^ -1, which is about 4 times and over 10^4 times larger tban those of the GO and completely reduced rGO membranes, respectively, and high rejection over 95700 for various dyes. Furthermore, they show better structure stability and more superior separation perfor- mance than GO membranes in acid and alkali environments.
基金supported by CAS/SAFEA International Partnership Program for Creative Research Teams,the Pilot Project of Knowledge Innovation of CAS (Grant No. KZCX2-YW-105)National Basic Research Program of China (Grant No. 2006CB806400)National Natural Science Foundation of China (Grant Nos. 40402002,40872011)
文摘Leaf cuticle analysis has long been a powerful tool for fossil plant identification, systematics, and palaeoclimatological recon- struction. In recent decades the application of stomatal frequency data that are relied on precise calculation of stomata on plant fossil cuticles to reconstruct ancient atmospheric CO2 concentration made the preparation of cuticular membrane with sufficient size a critical technique in palaeoclimatological research. However, for plants with originally thin and fragile cuticles, e.g., most deciduous plants, conventional techniques sometimes fail to obtain cuticular membranes with sufficient size, or sometimes unable to recover any. This has largely hampered the usage of fossil cuticle analysis in palaeobotanical and palaeo- climatological research. Here, we describe a new method using clear nail polish as a medium to "strengthen" the originally thin and fragile cuticles prior to maceration procedures. We demonstrate the method by using middle Eocene Metasequoia fossils that were notorious for the difficulty of recovering large-sized clean cuticular membranes due to their thin and fragile nature. Metasequoia, with well-documented and widely-distributed fossil records since the Late Cretaceous and with a living repre- sentative, 114. glyptostroboides, as a comparative reference, bas been widely used as a model genus for the study of evolution of plants, palaeoclimatological reconstruction, and plant adaptation to climate changes. But its deciduous habit produces thin cuticles and makes the preparation of clean cuticular membranes a tedious process. The new method successfully allows us to recover its delicate cuticular membranes with sufficient sizes for SEM observation and stomatal frequency analysis.
基金supported by the National Natural Science Foundation of China (20676073)
文摘A simple and cost-effective method has been developed for the fabrication of microtubular solid oxide fuel cells (MT-SOFCs). Highly asymmetric electrolyte hollow fibers composed of a thin dense skin layer and a thick porous substrate are first prepared by a modified phase inversion/sintering technique. The porous substrate is then formed into the anode by deposition of a Ni catalyst via an electroless plating method inside the pores while the thin dense skin layer serves directly as the electrolyte film of the fuel cells. A porous cathode layer is produced on the outer surface of the Ni-deposited hollow fibers by slurry coating and subsequent sintering to form a complete micro tubular fuel cell. The process has been employed to fabricate yttrium stabilized zirconia (YSZ) supported Ni-YSZ-YSZ-La0.6Sr0.4Co0.2Fe0.8O3-(LSCF) microtubular fuel cells. The maximum output of the resulting cells is 159.6 mW cm-2 at 800 °C when using H2 as the fuel feed and air as the oxidant.
基金supported by the National Basic Research Program of China(No.2012CB723405)the Science and Technology Commission of Shanghai Municipality(Nos.13510500300,14DZ1201403 and 14511105602)
文摘In this paper, a partial discharge detection system is proposed using an optical fiber Fabry-Perot(FP) interferometric sensor, which is fabricated by photolithography. SU-8 photoresist is employed due to its low Young's modulus and potentially high sensitivity for ultrasound detection. The FP cavity is formed by coating the fiber end face with two layers of SU-8 so that the cavity can be controlled by the thickness of the middle layer of SU-8. Static pressure measurement experiments are done to estimate the sensing performance. The results show that the SU-8 based sensor has a sensitivity of 154.8 nm/kP a, which is much higher than that of silica based sensor under the same condition. Moreover, the sensor is demonstrated successfully to detect ultrasound from electrode discharge.