The important parameters that influence the mechanical property of the pavinglayer on an orthotropic steel bridge deck are the paving layer thickness and modulus of the asphaltconcrete surfacing. Three important indic...The important parameters that influence the mechanical property of the pavinglayer on an orthotropic steel bridge deck are the paving layer thickness and modulus of the asphaltconcrete surfacing. Three important indices that control the typical failures of the paving layerare the maximum tensile stress of paving layer, the maximum shear stress between the steel deck andthe paving layer, and the maximum deflection on the paving surface. In this paper, the analyticalmodel of paving systems on orthotropic steel bridge deck is established, and the finite elementmethod is adopted to study the stress and strain of paving system. With the variation of asphaltconcrete modulus in high or low temperature season, the influences of paving layer thickness onthree control indices are researched. The results provide a theoretical basis for the determinationof thickness of the paving layer on the steel bridge deck.展开更多
Ti O2-organic multilayered nanocomposite films were deposited on a self-assembled monolayer-coated silicon substrate based on layer-by-layer technique and chemical bath deposition method by a hydrolysis of Ti Cl4 in a...Ti O2-organic multilayered nanocomposite films were deposited on a self-assembled monolayer-coated silicon substrate based on layer-by-layer technique and chemical bath deposition method by a hydrolysis of Ti Cl4 in an acid aqueous solution. The chemical compositions, surface morphologies and mechanical properties of the films were investigated by X-ray photoelectron spectrometer(XPS), scanning electron microscopy(SEM) and nanoindentation depth-sensing technique, respectively. The results indicate that the major chemical compositions of the films are Ti and O. The principal mechanism for the nucleation and growth of the films is homogeneous nucleation, and the layer number of films has great influence on the surface morphology and roughness of the films. In addition, mechanical nanoindentation testing presents a significant increase in hardness and fracture toughness of titanium dioxide multilayered films compared with single-layer titanium dioxide thin film.展开更多
The mechanism of a hydro-viscous soft start is of great importance in the design of a hydro-viscous clutch and its control system. To explain the mechanism of a hydro-viscous soft start, the startup process of a belt ...The mechanism of a hydro-viscous soft start is of great importance in the design of a hydro-viscous clutch and its control system. To explain the mechanism of a hydro-viscous soft start, the startup process of a belt conveyor was numerically analyzed with the modified Reynolds equation, an energy equation and a temperature-viscosity equation. The effect of temperature and grooves of the friction disk surface on torque transfer and load capacity of the oil film have also been analyzed. The results show that 1) the grooves are the basis of forming dynamic pressure but they may reduce the capacity of torque transfer to a certain extent, 2) during the startup process, temperature has little effect on torque transfer and load capacity and the variation in load capacity of the oil film is very small, indicating that it is preferable to use the flow rate as a control object than the pressure of the feed cylinder. The results have been verified by an experiment.展开更多
Chitosan is a natural cationic polysaccharide, which is often used for preparing biomedical materials because of its high biocompatibility. In this study, chitosan with a molecular weight of 160 kDa was chosen to prep...Chitosan is a natural cationic polysaccharide, which is often used for preparing biomedical materials because of its high biocompatibility. In this study, chitosan with a molecular weight of 160 kDa was chosen to prepare chitosan nanoparticles （CSNPs） as gene vectors by ionic cross-linking with tripolyphosphate （TPP）. CSNPs were characterized in terms of particle size, zeta potential, and polydispersity index （PDI） using a Zetasizer, and morphology was evaluated by transmission electron microscopy （TEM）. Furthermore, the cytotoxicity and biocompatibility of CSNPs were correspondingly examined by a 3-（4,5-dimethylthiazol-2-yl）-2,5- diphenyltetrazolium bromide （MTT） assay and histological examination. Agarose gel electrophoresis and UV spectrophotometric methods were performed to measure the loading capacity. The cell transfection efficiency of CSNPs loaded with plasmids or siRNA was analyzed by fluorescence microscopy or laser scanning confocal microscopy. The results showed that CSNPs were prepared successfully by the ionic gelation method, which had a smaller partcticle size （100 nm-200 nm）, stable dispersibility, low cytotoxicity, good tissue-biocompatibility, and high gene-loading efficiency. These CSNPs could transfer the plasmids or siRNA to cells. However, CSNPs might have a much higher transfection efficiency for siRNAs than for plasmids, which implies that CSNPs might be a safer and more efficient vector for delivering siRNAs rather than plasmids.展开更多
文摘The important parameters that influence the mechanical property of the pavinglayer on an orthotropic steel bridge deck are the paving layer thickness and modulus of the asphaltconcrete surfacing. Three important indices that control the typical failures of the paving layerare the maximum tensile stress of paving layer, the maximum shear stress between the steel deck andthe paving layer, and the maximum deflection on the paving surface. In this paper, the analyticalmodel of paving systems on orthotropic steel bridge deck is established, and the finite elementmethod is adopted to study the stress and strain of paving system. With the variation of asphaltconcrete modulus in high or low temperature season, the influences of paving layer thickness onthree control indices are researched. The results provide a theoretical basis for the determinationof thickness of the paving layer on the steel bridge deck.
基金Projects(51204036,51234009)supported by the National Natural Science Foundation of ChinaProject(2014CB643405)supported by the National Basic Research Program of China
文摘Ti O2-organic multilayered nanocomposite films were deposited on a self-assembled monolayer-coated silicon substrate based on layer-by-layer technique and chemical bath deposition method by a hydrolysis of Ti Cl4 in an acid aqueous solution. The chemical compositions, surface morphologies and mechanical properties of the films were investigated by X-ray photoelectron spectrometer(XPS), scanning electron microscopy(SEM) and nanoindentation depth-sensing technique, respectively. The results indicate that the major chemical compositions of the films are Ti and O. The principal mechanism for the nucleation and growth of the films is homogeneous nucleation, and the layer number of films has great influence on the surface morphology and roughness of the films. In addition, mechanical nanoindentation testing presents a significant increase in hardness and fracture toughness of titanium dioxide multilayered films compared with single-layer titanium dioxide thin film.
文摘The mechanism of a hydro-viscous soft start is of great importance in the design of a hydro-viscous clutch and its control system. To explain the mechanism of a hydro-viscous soft start, the startup process of a belt conveyor was numerically analyzed with the modified Reynolds equation, an energy equation and a temperature-viscosity equation. The effect of temperature and grooves of the friction disk surface on torque transfer and load capacity of the oil film have also been analyzed. The results show that 1) the grooves are the basis of forming dynamic pressure but they may reduce the capacity of torque transfer to a certain extent, 2) during the startup process, temperature has little effect on torque transfer and load capacity and the variation in load capacity of the oil film is very small, indicating that it is preferable to use the flow rate as a control object than the pressure of the feed cylinder. The results have been verified by an experiment.
基金supported by the Natural Science Foundation of Shandong Province(No.ZR2014HP011)Qingdao Young Scientist Applied Basic Research Fund(No.15-9-1-51-jch)+1 种基金Youth Foundation of The Affiliated Hospital of Qingdao University(No.2417)the National Natural Science Foundation of China(No.81401899)
文摘Chitosan is a natural cationic polysaccharide, which is often used for preparing biomedical materials because of its high biocompatibility. In this study, chitosan with a molecular weight of 160 kDa was chosen to prepare chitosan nanoparticles （CSNPs） as gene vectors by ionic cross-linking with tripolyphosphate （TPP）. CSNPs were characterized in terms of particle size, zeta potential, and polydispersity index （PDI） using a Zetasizer, and morphology was evaluated by transmission electron microscopy （TEM）. Furthermore, the cytotoxicity and biocompatibility of CSNPs were correspondingly examined by a 3-（4,5-dimethylthiazol-2-yl）-2,5- diphenyltetrazolium bromide （MTT） assay and histological examination. Agarose gel electrophoresis and UV spectrophotometric methods were performed to measure the loading capacity. The cell transfection efficiency of CSNPs loaded with plasmids or siRNA was analyzed by fluorescence microscopy or laser scanning confocal microscopy. The results showed that CSNPs were prepared successfully by the ionic gelation method, which had a smaller partcticle size （100 nm-200 nm）, stable dispersibility, low cytotoxicity, good tissue-biocompatibility, and high gene-loading efficiency. These CSNPs could transfer the plasmids or siRNA to cells. However, CSNPs might have a much higher transfection efficiency for siRNAs than for plasmids, which implies that CSNPs might be a safer and more efficient vector for delivering siRNAs rather than plasmids.
