Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environ...Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.展开更多
This paper attempts to estimate the ultimate strength of a laminated composite only based on its con- stituent properties measured independently. Three important issues involved have been systematically addressed, i.e...This paper attempts to estimate the ultimate strength of a laminated composite only based on its con- stituent properties measured independently. Three important issues involved have been systematically addressed, i.e., stress calculation for the constituent fiber and matrix materials, failure detection for the lamina and laminate upon the internal stresses in their constituents, and input data determination of the constituents from monolithic measurements. There are three important factors to influence the accuracy of the strength prediction. One is the stress concentration factor （SCF） in the matrix. Another is matrix plasticity. The third is thermal residual stresses in the constituents. It is these three factors, however, that have not been sufficiently well realized in the composite community. One can easily find out the elastic and strength parameters of a great many laminae and laminates in the current literature. Unfortunately, necessary information to determine the SCF, the matrix plasticity, and the thermal residual stresses of the composites is rare or incomplete. A useful design methodology is demonstrated in the paper.展开更多
The process to prepare pure phase of hexagonal Y2O2S was investigated. Effect of mixed flux of Na2CO3 and S amounts was studied. The phase composition and morphology were characterized by X-ray diffraction （XRD） and...The process to prepare pure phase of hexagonal Y2O2S was investigated. Effect of mixed flux of Na2CO3 and S amounts was studied. The phase composition and morphology were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results showed that the single phase of Y2O2S with smooth morphology could not be obtained as the molar ratio of Y2O3, Na2CO3 and S was in the range of 1：（0.5-1）：（2-3） until the molar ratio was increased to 1：1.5：4. Different Er3＋ concentration doped Y2O2S：Er powders were prepared with molar ratio of the raw materials 1：1.5：4. The quenching concentration of Er3＋ in Y2O2S was more than 2 mol.%, which was due to the interaction of electric quadrupoles between Er3＋ ions.展开更多
文摘Fluorene is a polycyclic aromatic hydrocarbon, which is a hazardous toxic chemical in the environment. The measurement of low concentrations of fluorene is a subject of intense interest in chemistry and in the environment. Polypyrrole chitosan cobalt ferrite nanoparticles are prepared using the electrochemical method. The prepared layers are characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The layers are used to detect fluorene using the surface plasmon resonance technique at room temperature. The composite layer is evaluated after detection of fluorene using atomic force microscopy. The fluorene is bound on the layer, and the shift of the resonance angle is about 0.0052°, corresponding to the limitation of 0.01 ppm.
基金supported by the National Natural Science Foundation of China(11272238)Doctoral Fund of Ministry of Education of China(20120072110036)
文摘This paper attempts to estimate the ultimate strength of a laminated composite only based on its con- stituent properties measured independently. Three important issues involved have been systematically addressed, i.e., stress calculation for the constituent fiber and matrix materials, failure detection for the lamina and laminate upon the internal stresses in their constituents, and input data determination of the constituents from monolithic measurements. There are three important factors to influence the accuracy of the strength prediction. One is the stress concentration factor （SCF） in the matrix. Another is matrix plasticity. The third is thermal residual stresses in the constituents. It is these three factors, however, that have not been sufficiently well realized in the composite community. One can easily find out the elastic and strength parameters of a great many laminae and laminates in the current literature. Unfortunately, necessary information to determine the SCF, the matrix plasticity, and the thermal residual stresses of the composites is rare or incomplete. A useful design methodology is demonstrated in the paper.
基金Project supported by Military Coordination Scientific Research Projects (JPPT-1486)the Priority Academic Program Development of Jiangsu Higher Education Institutions (CXZZ11_0333)
文摘The process to prepare pure phase of hexagonal Y2O2S was investigated. Effect of mixed flux of Na2CO3 and S amounts was studied. The phase composition and morphology were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results showed that the single phase of Y2O2S with smooth morphology could not be obtained as the molar ratio of Y2O3, Na2CO3 and S was in the range of 1：（0.5-1）：（2-3） until the molar ratio was increased to 1：1.5：4. Different Er3＋ concentration doped Y2O2S：Er powders were prepared with molar ratio of the raw materials 1：1.5：4. The quenching concentration of Er3＋ in Y2O2S was more than 2 mol.%, which was due to the interaction of electric quadrupoles between Er3＋ ions.
