Differential electrolytic potentiometry （DEP） was coupled with Flow injection analysis （FIA） technique for the determination of Procainamide in pharmaceutical preparations. Platinum electrodes were used as an indi...Differential electrolytic potentiometry （DEP） was coupled with Flow injection analysis （FIA） technique for the determination of Procainamide in pharmaceutical preparations. Platinum electrodes were used as an indicating system to follow the oxidation of Procainamide with cerium（IV）, and permanganate in an acidic medium. The oxidation reactions of Procainamide with Ce（IV） and/or permanganate are fast enough to permit its determination by flow injection in sulfuric acid media. The univariate method was employed to optimize the variables such as the current density, the flow rate, the oxidant concentration and the concentration of sulfuric acid. The proposed method was linear in the range 20-100 μg.mL^-1 , the DL and R2 values were 12 μg.mL^-1 and 0.995 respectively. The procedure was applied successfully to the determination of Procainamide in commercial tablets. The results of this study were favorably compared statistically with those obtained with official methods.展开更多
Temperature as an indicator of tissue response is widely used in clinical applications. In view of above a problem of temperature distribution in peripheral regions of extended spherical organs of a human body like, h...Temperature as an indicator of tissue response is widely used in clinical applications. In view of above a problem of temperature distribution in peripheral regions of extended spherical organs of a human body like, human breast involving uniformly perfused tumor is investigated in this paper. The human breast is assumed to be spherical in shape with upper hemisphere projecting out from the trunk of the body and lower hemisphere is considered to be a part of the body core. The outer surface of the breast is assumed to be exposed to the environment from where the heat loss takes place by conduction, convection, radiation and evaporation. The heat transfer from core to the surface takes place by thermal conduction and blood perfusion. Also metabolic activity takes place at different rates in different layers of the breast. An elliptical-shaped tumor is assumed to be present in the dermis region of human breast. A finite element model is developed for a two-dimensional steady state case incorporating the important parameters like blood flow, metabolic activity and thermal conductivity. The triangular ring elements are employed to discretize the region. Appropriate boundary conditions are framed using biophysical conditions. The numerical results are used to study the effect of tumor on temperature distribution in the region.展开更多
The proton implantation is one of key procedures to confine the current diffusion in vertical cavity surface emitting lasers(VCSELs),in which the proton implanted depth and profile are main parameters.Threshold charac...The proton implantation is one of key procedures to confine the current diffusion in vertical cavity surface emitting lasers(VCSELs),in which the proton implanted depth and profile are main parameters.Threshold characteristics of VCSELs with various proton implanted depths are studied after optical,electrical and thermal fields have been simulated self-consistently in three dimensions.It is found that for VCSELs with confinement radius of 2 mm,increasing proton implanted depth can reduce the injected current threshold power and enhance the laser temperature in active region.Numerical results also indicate that there are optimal values for current aperture in proton implanted VCSELs.The minimum injected current threshold can be achieved in VCSELs with proton implantation near the active region and confinement radius of 1.5 mm,while the VCSELs with proton implantation in the middle of p-type distributed Bragg reflectors(DBRs) and confinement radius of 2.5 mm can realize the minimum temperature.展开更多
文摘Differential electrolytic potentiometry （DEP） was coupled with Flow injection analysis （FIA） technique for the determination of Procainamide in pharmaceutical preparations. Platinum electrodes were used as an indicating system to follow the oxidation of Procainamide with cerium（IV）, and permanganate in an acidic medium. The oxidation reactions of Procainamide with Ce（IV） and/or permanganate are fast enough to permit its determination by flow injection in sulfuric acid media. The univariate method was employed to optimize the variables such as the current density, the flow rate, the oxidant concentration and the concentration of sulfuric acid. The proposed method was linear in the range 20-100 μg.mL^-1 , the DL and R2 values were 12 μg.mL^-1 and 0.995 respectively. The procedure was applied successfully to the determination of Procainamide in commercial tablets. The results of this study were favorably compared statistically with those obtained with official methods.
文摘Temperature as an indicator of tissue response is widely used in clinical applications. In view of above a problem of temperature distribution in peripheral regions of extended spherical organs of a human body like, human breast involving uniformly perfused tumor is investigated in this paper. The human breast is assumed to be spherical in shape with upper hemisphere projecting out from the trunk of the body and lower hemisphere is considered to be a part of the body core. The outer surface of the breast is assumed to be exposed to the environment from where the heat loss takes place by conduction, convection, radiation and evaporation. The heat transfer from core to the surface takes place by thermal conduction and blood perfusion. Also metabolic activity takes place at different rates in different layers of the breast. An elliptical-shaped tumor is assumed to be present in the dermis region of human breast. A finite element model is developed for a two-dimensional steady state case incorporating the important parameters like blood flow, metabolic activity and thermal conductivity. The triangular ring elements are employed to discretize the region. Appropriate boundary conditions are framed using biophysical conditions. The numerical results are used to study the effect of tumor on temperature distribution in the region.
基金supported by the Natural Science Foundation of Hebei Province (No.F2007000096)the Research Foundation for the Doctoral Program of Higher Education of China (No.20070080001)
文摘The proton implantation is one of key procedures to confine the current diffusion in vertical cavity surface emitting lasers(VCSELs),in which the proton implanted depth and profile are main parameters.Threshold characteristics of VCSELs with various proton implanted depths are studied after optical,electrical and thermal fields have been simulated self-consistently in three dimensions.It is found that for VCSELs with confinement radius of 2 mm,increasing proton implanted depth can reduce the injected current threshold power and enhance the laser temperature in active region.Numerical results also indicate that there are optimal values for current aperture in proton implanted VCSELs.The minimum injected current threshold can be achieved in VCSELs with proton implantation near the active region and confinement radius of 1.5 mm,while the VCSELs with proton implantation in the middle of p-type distributed Bragg reflectors(DBRs) and confinement radius of 2.5 mm can realize the minimum temperature.
