Optimum transit angles of millimeter-wave Si IMPATT diodes
Optimum transit angles for maximum output power in the millimeter-wave IMPATT diodes are calculated analytically by considering the carrier diffusion process through the space-charge region. It is found that the optimum transit angle decreases, as the space-charge layer width reduces. The theoretical results show satisfactory agreement with the previously published experimental results for Si p+-n-n+abrupt junction diodes.
Theory of the mm Wave IMPATT Diode: A Review
Due to revived interest in mm wave technology, a lot of research work is going on, on the theoretical, experimental and technological innovation on mm wave Impatt diode. In this review, a search is made on the available theories on mm wave Impatt diode which helps in understanding the experimental results and also gives a physical insight to the device operation. Drift-diffusion model, MITATT mode operation, velocity-energy transport equation are the few tested so far. Sometimes, closed form solution does not give a good agreement with experiment and hence computer simulation is applied. Energy-momentum simulation for GaAs mm wave Impatt gives a better agreement with experiment compared to drift-diffusion model. However, for Si mm wave Impatt even simulation with conventional Impatt equations are good enough for experimental verification.
Evaluation of antioxidants by a rapid polarographic method
A simple, rapid, precise, and reproducible method and an adaptable apparatus for polarographic measurement of lipid peroxidation and antioxidant activity is described. This method measures antioxidant activity within a few min time as compared to the hours or days needed for several widely used methods. Peroxidation rates were measured for different lipids as a function of amount of lipid, and amount of biocatalyst. The method is applicable to the detection and measurement of the antioxidant effects exhibited by weak antioxidants and has been satisfactorily used for the measurement of the antioxidant activity of different concentrations of powerful antioxidants.