Hyaluronic acid(HA, 20–50 kDa) is a hydrophilic macromolecule with anti-wrinkle effects and moisturizing properties. However, its high molecular weight prevents it from penetrating into the deeper layers of the skin ...Hyaluronic acid(HA, 20–50 kDa) is a hydrophilic macromolecule with anti-wrinkle effects and moisturizing properties. However, its high molecular weight prevents it from penetrating into the deeper layers of the skin and, thus, limits its benefits to topical effects. Thus, the objective of this study is to prepare nanoparticles of quaternized cyclodextrin-grafted chitosan(QCD-g-CS) associated with HA in different molar ratios of QCD-g-CS and HA. The conjugation of the carboxylic moieties of HA and the amides of QCD-g-CS was confirmed by Fourier-transform infrared spectroscopy. Thus, the system was optimized to create nanoparticles with a small size(235.63 ± 21.89 nm), narrow polydispersity index(0.13 ± 0.02), and zeta potential of 16.07 ± 0.65 m V. The association efficiency and loading efficiency were determined by ultra-performance liquid chromatography as 86.77 ± 0.69% and 10.85 ± 0.09%, respectively. The spherical morphology of the obtained nanoparticles was confirmed by transmission electron microscopy. Moreover, the in-vitro hydrating ability was significantly higher( P < 0.001) than that of bulk HA(3.29 ± 0.41 and 1.71 ± 0.05 g water/g sample, respectively). The safety of these nanoparticles at concentrations in the range of 0.01–0.10 mg/ml was confirmed via tests on human skin fibroblasts. Together, these results demonstrate that the developed nanoparticles are promising for future applications in cosmetics.展开更多
The three-dimensional hierarchical CuO and Au nanoparticles were synthesized by the hydrothermal method, respectively. The hierarchical CuO and the Au nanoparticles samples were characterized by X-ray diffraction and ...The three-dimensional hierarchical CuO and Au nanoparticles were synthesized by the hydrothermal method, respectively. The hierarchical CuO and the Au nanoparticles samples were characterized by X-ray diffraction and scanning electronic microscope, respectively. The as-synthesized CuO was assembled regularly from the nanosheets with thickness of 100 nm. The size of Au nanoparticles ranged from 50 to 200 nm. The hierarchical CuO gas sensors modified by different concentration of gold were fabricated. All the Au-loaded CuO gas sensors enhanced the response to ethanol and xylene while reducing the response to methanol, acetone, and formaldehyde. The results indicate that the Au nanoparticles prepared with PVP as surfactant can improve the selectivity of CuO gas sensors to ethanol gas for other common organic volatile gases. The improvement of gas sensing is mainly attributed to the different catalytic efficiency of the Au nanoparticles for different reactions. Meanwhile, the related mechanisms are discussed.展开更多
Nanoparticles can be taken as additives and added into various fluids to improve their lubricating performances. At present, researches in this area are mainly concentrated on the improvement effects of nanoparticles ...Nanoparticles can be taken as additives and added into various fluids to improve their lubricating performances. At present, researches in this area are mainly concentrated on the improvement effects of nanoparticles on the lubricating performances of liquid such as oil and water. Nanoparticles will also affect gas lubrication, but few related studies have been reported. Nanoparticles-laden gas film (NLGF) is formed when adding nanoparticles into gas bearing. Then, the lubricating performances of gas bearing including pressure distribution and load-carrying capacity will change. The variations of pressure distribution and load-carrying capacity in nanoparticles-laden gas film thrust bearing are investigated by numerical method. Taking account of the compressibility of gas and the interactions between gas and nanoparticles, a computational fluid dynamics model based on Navier-Stokes equations is applied to simulate the NLGF flow. The effects of inlet nanoparticles volume fraction and orifice radius on film pressure distribution and load-carrying capacity of the NLGF are calculated. The numerical calculation results show that both of the film land pressure and the maximum film pressure both increase when the nanoparticles are added into gas bearing, and the film pressures increase with the rising of the inlet nanoparticles volume fraction. The nanoparticles have an enhancement effect on load-carrying capacity of the studied bearing, and the enhancement effect becomes greater as the film thickness decrease. Therefore, nanoparticles can effectively improve the lubricating performance of gas bearing. The proposed research provides a theoretical basis for the design of new-type nanoparticles-laden gas film bearings.展开更多
Nanosized calcium carbonate particles were prepared with a continuous gas-liquid membrane contactor. The effects of Ca(OH)2 concentration, CO2 pressure and liquid flow velocity on the particles morphology, pressure dr...Nanosized calcium carbonate particles were prepared with a continuous gas-liquid membrane contactor. The effects of Ca(OH)2 concentration, CO2 pressure and liquid flow velocity on the particles morphology, pressure drop and membrane fouling were studied. With rising Ca(OH)2 concentrations, the average size of the particles increased. The effects of Ca(OH)2 concentration and CO2 pressure on particles were not apparent under the experimental conditions. When the Ca(OH)2 concentration and liquid flow velocity were high, or the CO2 pressure was low, the fouling on the membrane external surface at the contactor entrance was serious due to liquid leakage, whereas the fouling was slight at exit. The fouling on the membrane inner-surface at entrance was apparent due to adsorption of raw materials. The membrane can be recovered by washing with dilute hydrochloric acid and reused for at least 6 times without performance deterioration.展开更多
The main goal of this work is to explore the possibility of using Au-modified hydroxyapatite(HA) as a potential sensor material. Tube-like HA structure was fabricated with the aid of a Nafion N-117 cation exchange mem...The main goal of this work is to explore the possibility of using Au-modified hydroxyapatite(HA) as a potential sensor material. Tube-like HA structure was fabricated with the aid of a Nafion N-117 cation exchange membrane and gold(Au) nanoparticles were added by a hydrothermal method. The morphology, structure and composition were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), and X-ray photoelectron spectroscopy(XPS). The gas sensing properties were also investigated. Results show that Au nanoparticles are dispersed into the HA powder, which is tube-like, with rough inner and outer surfaces. Compared with pure HA, Au-modified HA exhibits improved sensing properties for NH_3. 5%(mass fraction) Au-modified HA shows the highest response with relatively short response/recovery time. The response is up to 79.2% when the corresponding sensor is exposed to 200×10^(-6) NH_3 at room temperature, and the response time and recovery time are 20 s and 25 s, respectively. For lower concentration, like 50×10^(-6), the response is still up to 70.8%. Good selectivity and repeatability are also observed. The sensing mechanism of high response and selectivity for NH_3 gas was also discussed. These results suggest that Au-HA composite is a promising material for NH_3 sensors operating at room temperature.展开更多
Porous cube-like crystalline In2O3 nanoparticles with an average diagonal length of 34.8 nm were fabricated by a laser ablation-reflux process to form In（OH）3, followed by a calcination treatment to yield porous In2...Porous cube-like crystalline In2O3 nanoparticles with an average diagonal length of 34.8 nm were fabricated by a laser ablation-reflux process to form In（OH）3, followed by a calcination treatment to yield porous In2O3. HRTEM （high-resolution transmission electronic microscopy）, XRD （X-ray diffraction）, BET （Brunauer-Emmett-Teller）, and XPS （X-ray photoelectron spectroscopy） analysis were used to characterize their crystalline structures, grain sizes, surface areas, and surface compositions. The as-prepared porous in-dium oxides were tested for their sensing properties toward ethanol. Non-porous In2O3 nanopowder （about 40 nm） was also examined in order to compare the results with the as-prepared porous In2O3 nanomaterials. The porous In2O3 exhibited much better performance than that of non-porosus In2O3, and showed enhanced sensitivity with a lower detection limit than other reported In2O3-based materials when exposed to ethanol. Good gas sensitivity and linear behavior as a function of ethanol concentration were observed in the porous In2O3 nanoparticles.展开更多
Chitosan(CS)nanofibers containing silver nanoparticles(AgNPs)were prepared by in-situ reducing method.A water soluble carboxymethyl chitosan(CMCT)was applied for the preparation of AgNPs.The impact factor such as the ...Chitosan(CS)nanofibers containing silver nanoparticles(AgNPs)were prepared by in-situ reducing method.A water soluble carboxymethyl chitosan(CMCT)was applied for the preparation of AgNPs.The impact factor such as the concentration of CMCT,silver nitrate(AgNO_3)content,temperature and the heating time during the preparation of AgNPs were studied.The result showed that the proper value of the concentration of CMCT,AgNO_3content,temperature and the heating time were set as0.1%,20μL AgNO_3(1.7 mol/L),90°and 3 h,separately and the maximum concentration of AgNPs could be acquired.To solve the spinnability of chitosan nanofiber,a super high molecular weight polyethylene oxide(PEO)was introduced to the system,and a new mixed solvent system was prepared by adding acetic acid,dimethyl sulfoxide(DMSO)and several drops of Triton X-100TMto distilled water.CS/PEO(80/20)with the concentration of 3%was dissolved in the mixed solvent to prepare electrospinning solution for CS/PEO(80/20)nanofiber fabrication.The CS containing AgNPs electrospun solution could be prepared by replacing the distilled water to silver nanoparticle solution during the preparation of mixed solvent.Ultraviolet visible(UV-Vis)spectra and transmission electron microscope(TEM)results showed that silver nanoparticles were prepared successfully.CS membranes with and without AgNPs were acquired via a traditional electrospinning equipment.These two nanofiber membranes were characterized by scanning electron microscope(SEM)images and mechanical testing.It could be noticed from the SEM images that there was a good morphology and random distribution for the nanofibers with an average fiber diameter of 180 nm.The mechanical property results showed that the addition of AgNPs decreased the mechanical strength significantly but the mechanical strength could still support wound dressing application.展开更多
Sn（OH）4 was prepared by the conventional solution precipitate method,followed by supercritical CO2 drying.The resultant Sn（OH）4 was divided into three aliquots and calcined at 400,600 and 800 °C,respectively,...Sn（OH）4 was prepared by the conventional solution precipitate method,followed by supercritical CO2 drying.The resultant Sn（OH）4 was divided into three aliquots and calcined at 400,600 and 800 °C,respectively,thus SnO2 nanoparticles with average crystallite sizes of 5,10 and 25 nm were obtained.Furthermore,three SnO2 thick film gas sensors（denoted as sensors S-400,S-600 and S-800） were fabricated from the above SnO2 nanoparticles.The adhesion of sensing materials on the surface of alumina tube is good.Compared to the sensors S-600 and S-800,sensor S-400 showed a much higher sensitivity to 1000 μL/L ethanol.On the other hand,sensor S-800 showed a much lower intrinsic resistance and improved selectivity to ethanol than sensors S-400 and S-600.X-Ray diffraction（XRD）,transmission electron microscopy（TEM） and selective area electron diffraction（SAED） measurements were used to characterize the SnO2 nanoparticles calcined at different temperatures.The differences in the gas sensing performance of these sensors were analyzed on the basis of scanning electron microscopy（SEM）.展开更多
Four types of nanoparticles,amorphous carbon,ironⅢoxide,SiO2,and amino-coated SiO2,were tested to determine changes in tetrahydrofuran-water(THF-water)clathrate hydrate nucleation and agglomeration.Rates were experim...Four types of nanoparticles,amorphous carbon,ironⅢoxide,SiO2,and amino-coated SiO2,were tested to determine changes in tetrahydrofuran-water(THF-water)clathrate hydrate nucleation and agglomeration.Rates were experimentally found to determine their viability for preventing natural gas hydrates from developing during offshore drilling operations.THF-water clathrates were chosen as a model to represent gas hydrate growth at atmospheric pressure.Concentrations of each nanoparticle between 0.15%and 1.0%by weight were tested as a kinetic inhibitor to hydrate formation.Tests were repeated at various temperatures below the formation temperature of 4.4℃for THF-water clathrate hydrates.Measurements were made to identify how the concentration of THF affects the clathrate hydrates forming under static conditions between20%and 30%by mole of THF.The primary tests in this study were performed using a 20:80 THF/water ratio.Temperature increases during hydrate nucleation for THF-water were measured between-5 and 3℃.The range of ideal nanoparticle concentrations was found to be between 0.15%and 0.45%by weight for optimal static,kinetic inhibition of hydrate nucleation.At approximately 0.3%by weight,the most significant inhibition was observed under static conditions for all four types of nanoparticles tested.We found that functionalized amino-coated SiO2 nanoparticles,across all tests,significantly increased the time required for the formation of THF-water clathrate hydrates compared to the other three non-functionalized nanoparticles.The amorphous carbon and ironⅢoxide nanoparticles performed similarly across each test and were both the least effective in their inhibition of the clathrate hydrates of the four nanoparticles studied compared to a control.展开更多
Genetic algorithm and partial least square（GA-PLS）,kernel PLS（KPLS） and Levenberg-Marquardt artificial neural network（L-M ANN） techniques were used to investigate the correlation between retention time（RT） and...Genetic algorithm and partial least square（GA-PLS）,kernel PLS（KPLS） and Levenberg-Marquardt artificial neural network（L-M ANN） techniques were used to investigate the correlation between retention time（RT） and descriptors for 15 nanoparticle compounds obtained by the comprehensive two-dimensional gas chromatography system（GC × GC）.Application of the dodecanethiol monolayer-protected gold nanoparticle（MPN） column was for a high-speed separation as the second column of GC × GC.The L-M ANN model with the final optimum network architecture of [13-5-1] gave a significantly better performance than the other models.This is the first research on the quantitative structure-retention relationship（QSRR） of nanoparticle compounds using the GA-PLS,GA-KPLS and L-M ANN.展开更多
SnO_2 nanoparticles with the average size of 3.7 nm have been successfully synthesized by hydrothermal method. The particles were characterized by XRD,SEM and TEM.The XRD results show that the products are all at nano...SnO_2 nanoparticles with the average size of 3.7 nm have been successfully synthesized by hydrothermal method. The particles were characterized by XRD,SEM and TEM.The XRD results show that the products are all at nanometer scale, and the crystallite size increases with increasing of the heat-treatment temperature.The SEM and TEM photographs indicate that the particles are all monodispersed with narrow size distribution.展开更多
Tin oxide nanoparticles with the average size of 17.4 nm (firing at 600℃for 2 h) have been successfully prepared through a sol-gel process starting with tin dichloride and absolute ethanol as precursors.The particle...Tin oxide nanoparticles with the average size of 17.4 nm (firing at 600℃for 2 h) have been successfully prepared through a sol-gel process starting with tin dichloride and absolute ethanol as precursors.The particles were characterized by TGA,XRD,SEM and TEM.And preliminary sensing properties were given.展开更多
基金Mae Fah Luang University is acknowledged for facilities and financially supported in partfunded by Thailand Graduate Institute of Science and Technology(TGIST),National Science and Technology De-velopment Agency(NSTDA),Thailand(Project No.SCA-CO-2558-1026-TH)
文摘Hyaluronic acid(HA, 20–50 kDa) is a hydrophilic macromolecule with anti-wrinkle effects and moisturizing properties. However, its high molecular weight prevents it from penetrating into the deeper layers of the skin and, thus, limits its benefits to topical effects. Thus, the objective of this study is to prepare nanoparticles of quaternized cyclodextrin-grafted chitosan(QCD-g-CS) associated with HA in different molar ratios of QCD-g-CS and HA. The conjugation of the carboxylic moieties of HA and the amides of QCD-g-CS was confirmed by Fourier-transform infrared spectroscopy. Thus, the system was optimized to create nanoparticles with a small size(235.63 ± 21.89 nm), narrow polydispersity index(0.13 ± 0.02), and zeta potential of 16.07 ± 0.65 m V. The association efficiency and loading efficiency were determined by ultra-performance liquid chromatography as 86.77 ± 0.69% and 10.85 ± 0.09%, respectively. The spherical morphology of the obtained nanoparticles was confirmed by transmission electron microscopy. Moreover, the in-vitro hydrating ability was significantly higher( P < 0.001) than that of bulk HA(3.29 ± 0.41 and 1.71 ± 0.05 g water/g sample, respectively). The safety of these nanoparticles at concentrations in the range of 0.01–0.10 mg/ml was confirmed via tests on human skin fibroblasts. Together, these results demonstrate that the developed nanoparticles are promising for future applications in cosmetics.
基金Project supported by the Provincial Natural Science Foundation of Gansu (No. 1606RJZA026)the Scientific and Technological Project of Chengguan District of Lanzhou (No. 2016-2-4)Institute of Sensor Technology, Gansu Academy of Science
文摘The three-dimensional hierarchical CuO and Au nanoparticles were synthesized by the hydrothermal method, respectively. The hierarchical CuO and the Au nanoparticles samples were characterized by X-ray diffraction and scanning electronic microscope, respectively. The as-synthesized CuO was assembled regularly from the nanosheets with thickness of 100 nm. The size of Au nanoparticles ranged from 50 to 200 nm. The hierarchical CuO gas sensors modified by different concentration of gold were fabricated. All the Au-loaded CuO gas sensors enhanced the response to ethanol and xylene while reducing the response to methanol, acetone, and formaldehyde. The results indicate that the Au nanoparticles prepared with PVP as surfactant can improve the selectivity of CuO gas sensors to ethanol gas for other common organic volatile gases. The improvement of gas sensing is mainly attributed to the different catalytic efficiency of the Au nanoparticles for different reactions. Meanwhile, the related mechanisms are discussed.
基金supported by National Natural Science Foundation of China (Grant No. 51175405)
文摘Nanoparticles can be taken as additives and added into various fluids to improve their lubricating performances. At present, researches in this area are mainly concentrated on the improvement effects of nanoparticles on the lubricating performances of liquid such as oil and water. Nanoparticles will also affect gas lubrication, but few related studies have been reported. Nanoparticles-laden gas film (NLGF) is formed when adding nanoparticles into gas bearing. Then, the lubricating performances of gas bearing including pressure distribution and load-carrying capacity will change. The variations of pressure distribution and load-carrying capacity in nanoparticles-laden gas film thrust bearing are investigated by numerical method. Taking account of the compressibility of gas and the interactions between gas and nanoparticles, a computational fluid dynamics model based on Navier-Stokes equations is applied to simulate the NLGF flow. The effects of inlet nanoparticles volume fraction and orifice radius on film pressure distribution and load-carrying capacity of the NLGF are calculated. The numerical calculation results show that both of the film land pressure and the maximum film pressure both increase when the nanoparticles are added into gas bearing, and the film pressures increase with the rising of the inlet nanoparticles volume fraction. The nanoparticles have an enhancement effect on load-carrying capacity of the studied bearing, and the enhancement effect becomes greater as the film thickness decrease. Therefore, nanoparticles can effectively improve the lubricating performance of gas bearing. The proposed research provides a theoretical basis for the design of new-type nanoparticles-laden gas film bearings.
基金Supported by the National Natural Science Foundation of China （20676016, 21076024）.
文摘Nanosized calcium carbonate particles were prepared with a continuous gas-liquid membrane contactor. The effects of Ca(OH)2 concentration, CO2 pressure and liquid flow velocity on the particles morphology, pressure drop and membrane fouling were studied. With rising Ca(OH)2 concentrations, the average size of the particles increased. The effects of Ca(OH)2 concentration and CO2 pressure on particles were not apparent under the experimental conditions. When the Ca(OH)2 concentration and liquid flow velocity were high, or the CO2 pressure was low, the fouling on the membrane external surface at the contactor entrance was serious due to liquid leakage, whereas the fouling was slight at exit. The fouling on the membrane inner-surface at entrance was apparent due to adsorption of raw materials. The membrane can be recovered by washing with dilute hydrochloric acid and reused for at least 6 times without performance deterioration.
基金Project(51272289) supported by the National Natural Science Foundation of China
文摘The main goal of this work is to explore the possibility of using Au-modified hydroxyapatite(HA) as a potential sensor material. Tube-like HA structure was fabricated with the aid of a Nafion N-117 cation exchange membrane and gold(Au) nanoparticles were added by a hydrothermal method. The morphology, structure and composition were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), and X-ray photoelectron spectroscopy(XPS). The gas sensing properties were also investigated. Results show that Au nanoparticles are dispersed into the HA powder, which is tube-like, with rough inner and outer surfaces. Compared with pure HA, Au-modified HA exhibits improved sensing properties for NH_3. 5%(mass fraction) Au-modified HA shows the highest response with relatively short response/recovery time. The response is up to 79.2% when the corresponding sensor is exposed to 200×10^(-6) NH_3 at room temperature, and the response time and recovery time are 20 s and 25 s, respectively. For lower concentration, like 50×10^(-6), the response is still up to 70.8%. Good selectivity and repeatability are also observed. The sensing mechanism of high response and selectivity for NH_3 gas was also discussed. These results suggest that Au-HA composite is a promising material for NH_3 sensors operating at room temperature.
基金the National Science Council of Taiwan for financially supporting this work.
文摘Porous cube-like crystalline In2O3 nanoparticles with an average diagonal length of 34.8 nm were fabricated by a laser ablation-reflux process to form In（OH）3, followed by a calcination treatment to yield porous In2O3. HRTEM （high-resolution transmission electronic microscopy）, XRD （X-ray diffraction）, BET （Brunauer-Emmett-Teller）, and XPS （X-ray photoelectron spectroscopy） analysis were used to characterize their crystalline structures, grain sizes, surface areas, and surface compositions. The as-prepared porous in-dium oxides were tested for their sensing properties toward ethanol. Non-porous In2O3 nanopowder （about 40 nm） was also examined in order to compare the results with the as-prepared porous In2O3 nanomaterials. The porous In2O3 exhibited much better performance than that of non-porosus In2O3, and showed enhanced sensitivity with a lower detection limit than other reported In2O3-based materials when exposed to ethanol. Good gas sensitivity and linear behavior as a function of ethanol concentration were observed in the porous In2O3 nanoparticles.
基金National Natural Science Foundations of China(Nos.31470941,31271035)Science and Technology Commissions of Shanghai Municipality,China(Nos.15JC1490100,15441905100)+3 种基金Ph.D.Programs Foundation of Ministry of Education of China(No.20130075110005)Light of Textile Project,China(No.J201404)Yantai Double Hundred Talent Plan,China(No.XY-04-16-06)“111 Project”Biomedical Textile Materials Science and Technology,China(No.B07024)
文摘Chitosan(CS)nanofibers containing silver nanoparticles(AgNPs)were prepared by in-situ reducing method.A water soluble carboxymethyl chitosan(CMCT)was applied for the preparation of AgNPs.The impact factor such as the concentration of CMCT,silver nitrate(AgNO_3)content,temperature and the heating time during the preparation of AgNPs were studied.The result showed that the proper value of the concentration of CMCT,AgNO_3content,temperature and the heating time were set as0.1%,20μL AgNO_3(1.7 mol/L),90°and 3 h,separately and the maximum concentration of AgNPs could be acquired.To solve the spinnability of chitosan nanofiber,a super high molecular weight polyethylene oxide(PEO)was introduced to the system,and a new mixed solvent system was prepared by adding acetic acid,dimethyl sulfoxide(DMSO)and several drops of Triton X-100TMto distilled water.CS/PEO(80/20)with the concentration of 3%was dissolved in the mixed solvent to prepare electrospinning solution for CS/PEO(80/20)nanofiber fabrication.The CS containing AgNPs electrospun solution could be prepared by replacing the distilled water to silver nanoparticle solution during the preparation of mixed solvent.Ultraviolet visible(UV-Vis)spectra and transmission electron microscope(TEM)results showed that silver nanoparticles were prepared successfully.CS membranes with and without AgNPs were acquired via a traditional electrospinning equipment.These two nanofiber membranes were characterized by scanning electron microscope(SEM)images and mechanical testing.It could be noticed from the SEM images that there was a good morphology and random distribution for the nanofibers with an average fiber diameter of 180 nm.The mechanical property results showed that the addition of AgNPs decreased the mechanical strength significantly but the mechanical strength could still support wound dressing application.
基金Supported by the National Natural Science Foundation of China(No.60906008)the Foundation for Excellent Middle-aged or Young Scientists from Shandong Province of China(No.BS2010CL007)
文摘Sn（OH）4 was prepared by the conventional solution precipitate method,followed by supercritical CO2 drying.The resultant Sn（OH）4 was divided into three aliquots and calcined at 400,600 and 800 °C,respectively,thus SnO2 nanoparticles with average crystallite sizes of 5,10 and 25 nm were obtained.Furthermore,three SnO2 thick film gas sensors（denoted as sensors S-400,S-600 and S-800） were fabricated from the above SnO2 nanoparticles.The adhesion of sensing materials on the surface of alumina tube is good.Compared to the sensors S-600 and S-800,sensor S-400 showed a much higher sensitivity to 1000 μL/L ethanol.On the other hand,sensor S-800 showed a much lower intrinsic resistance and improved selectivity to ethanol than sensors S-400 and S-600.X-Ray diffraction（XRD）,transmission electron microscopy（TEM） and selective area electron diffraction（SAED） measurements were used to characterize the SnO2 nanoparticles calcined at different temperatures.The differences in the gas sensing performance of these sensors were analyzed on the basis of scanning electron microscopy（SEM）.
文摘Four types of nanoparticles,amorphous carbon,ironⅢoxide,SiO2,and amino-coated SiO2,were tested to determine changes in tetrahydrofuran-water(THF-water)clathrate hydrate nucleation and agglomeration.Rates were experimentally found to determine their viability for preventing natural gas hydrates from developing during offshore drilling operations.THF-water clathrates were chosen as a model to represent gas hydrate growth at atmospheric pressure.Concentrations of each nanoparticle between 0.15%and 1.0%by weight were tested as a kinetic inhibitor to hydrate formation.Tests were repeated at various temperatures below the formation temperature of 4.4℃for THF-water clathrate hydrates.Measurements were made to identify how the concentration of THF affects the clathrate hydrates forming under static conditions between20%and 30%by mole of THF.The primary tests in this study were performed using a 20:80 THF/water ratio.Temperature increases during hydrate nucleation for THF-water were measured between-5 and 3℃.The range of ideal nanoparticle concentrations was found to be between 0.15%and 0.45%by weight for optimal static,kinetic inhibition of hydrate nucleation.At approximately 0.3%by weight,the most significant inhibition was observed under static conditions for all four types of nanoparticles tested.We found that functionalized amino-coated SiO2 nanoparticles,across all tests,significantly increased the time required for the formation of THF-water clathrate hydrates compared to the other three non-functionalized nanoparticles.The amorphous carbon and ironⅢoxide nanoparticles performed similarly across each test and were both the least effective in their inhibition of the clathrate hydrates of the four nanoparticles studied compared to a control.
文摘Genetic algorithm and partial least square（GA-PLS）,kernel PLS（KPLS） and Levenberg-Marquardt artificial neural network（L-M ANN） techniques were used to investigate the correlation between retention time（RT） and descriptors for 15 nanoparticle compounds obtained by the comprehensive two-dimensional gas chromatography system（GC × GC）.Application of the dodecanethiol monolayer-protected gold nanoparticle（MPN） column was for a high-speed separation as the second column of GC × GC.The L-M ANN model with the final optimum network architecture of [13-5-1] gave a significantly better performance than the other models.This is the first research on the quantitative structure-retention relationship（QSRR） of nanoparticle compounds using the GA-PLS,GA-KPLS and L-M ANN.
文摘SnO_2 nanoparticles with the average size of 3.7 nm have been successfully synthesized by hydrothermal method. The particles were characterized by XRD,SEM and TEM.The XRD results show that the products are all at nanometer scale, and the crystallite size increases with increasing of the heat-treatment temperature.The SEM and TEM photographs indicate that the particles are all monodispersed with narrow size distribution.
文摘Tin oxide nanoparticles with the average size of 17.4 nm (firing at 600℃for 2 h) have been successfully prepared through a sol-gel process starting with tin dichloride and absolute ethanol as precursors.The particles were characterized by TGA,XRD,SEM and TEM.And preliminary sensing properties were given.
基金Science&Technology Commission of Shanghai Municipality (No. 20DZ2254900)Municipal Public Welfare Research Project from Jiaxing,Zhejiang Province (No. 2022AY10001)Open Project Program of Jiaxing Key Laboratory of Virus-Related Infectious Diseases.
