Electrochemical response of the two isomers conjugated acids, maleic and fumaric, on glassy carbon electrode modified with platinum nanoparticles

Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) techniques are essentially used for the study of the electroreduction of the two isomers maleic and fumaric acid systems in 0.1 M KCl at 298 K. The measurements are carried out on Pt nanoparticles electrodeposited on glassy carbon electrode (GCE). The modification of the electrode enables the appearance of better resolved peaks of the cyclic voltammograms of the two isomers of the acids in comparison with the poor behavior in absence of the modification. Two well-separated reversible cathodic waves at ?0.44 and ?0.59 V versus Ag/AgCl are characterizing the electroreduction cyclic voltammogram of maleic acid. The electroreduction of fumaric acid shows only one reversible peak at ?0.362 V versus Ag/AgCl is observed. Peak separations and current functions together with other parameters of the electrochemical behavior of both isomers are calculated and discussed. Rate parameters of the anion radicals of both isomers in 0.1 M KCl on immobilized GCE with Pt nanoparticles are obtained and discussed.     

95-GHz scattering by terrain at near-grazing incidence

This study, consisting of three complimentary topics, examines the millimeter-wave backscattering behavior of terrain at incidence angles extending between 70 and 90°, corresponding to grazing angles of 20° to 0°. The first topic addresses the character of the statistical variability of the radar backscattering cross section per unit area σ_A. Based on an evaluation of an extensive data set acquired at 95 GHz, it was determined that the Rayleigh fading model (which predicts that σ_A is exponentially distributed) provides an excellent fit to the measured data for various types of terrain covers, including bare surfaces, grasses, trees, dry snow, and wet snow. The second topic relates to the angular variability and dynamic range of the backscattering coefficient σ⁰, particularly near grazing incidence. We provide a summary of data reported to date for each of several types of terrain covers. The last topic focuses on bare surfaces. A semi-empirical model for σ⁰ is presented for vertical (VV), horizontal (HH), and cross (HV) polarizations. The model parameters include the incidence angle &thetas;, the surface relative dielectric constant ϵ, and the surface roughness ks, where k=2π/λ and s is the surface root mean square (RMS) height     

MMW scattering by rough lossy dielectric cylinders and tree trunks

The millimeter-wave (MMW) radar backscatter response of a rough, lossy, dielectric cylinder is examined both analytically and experimentally. Models for both the coherent and incoherent components of the scattered field are developed based on the geometric-optics approximation. The accuracy of the analytical models and their applicability in predicting the backscatter response of tree trunks are determined experimentally by measuring the radar backscatter at 95 GHz from a rough conducting cylinder and from a section of a tree trunk. In both cases, very good agreement was achieved between the model predictions and the measurements