Determination of mitomycin C in plasma, serum and urine by high-performance liquid chromatography with ultra-violet and electrochemical detection

The performance of a number of normal phase and reversed-phase systems, with ultraviolet detection at 360 nm, has been investigated with respect to their applicability to pharmacokinetic studies of mitomycin C (MMC). The reversed-phase system developed was also combined with a polarographic detector in order to compare the sensitivity and selectivity of ultraviolet and electrochemical detection. A simple isolation procedure, based on the adsorption of MMC on a non-ionogenic resin, has been developed. The developed assay is applied to a pharmacokinetic study from which some examples are given.     

Calculation of high frequency ultrasonic signals for shear wave insonification in solid material

The goal of the theoretical part is to simulate an automatic ultrasonic inspection with contact technique shear wave probes, where the high frequency signals are captured and used to perform a reconstruction based on the synthetic aperture focusing method "SAFT". Therefore the ultrasonic probe, the scanning path and the defects are parameters in a CAD model. The scattering behavior of the defect is calculated by the Kirchhoff approximation in its elastodynamic version. The result of the simulation--the high frequency data--and the result of the SAFT-reconstructions are compared with experimental results on a steel test block with side drilled and flat bottom holes. The model is validated by the experiment. One of the applications of the model is to identify multiple reflections.     

Communication: Highest occupied molecular orbital-lowest unoccupied molecular orbital gaps of doped silicon clusters from core level spectroscopy

A method to determine band gaps of size-selected and isolated nanoparticles by combination of valence band and core-level photoionization spectroscopy is presented. This approach is widely applicable and provides a convenient alternative to current standard techniques for the determination of band gaps by optical or photoelectron spectroscopy. A first application to vanadium doped silicon clusters confirms a striking size-dependence of their highest occupied-lowest unoccupied molecular orbital gaps.     

Pulse propagation over smooth irregular terrain

The source of the electromagnetic field is assumed to be a vertical electric dipole at height ξ above the surface of the plane earth with arbitrary time varying moment. The problem of finding the transient field of this dipole when the earth is allowed to be slightly rough is solved by means of a perturbation analysis, repeated application of integral transforms and their inversion on the base of Cagniard's method with the modification of de Hoop.     

Transient fields of linear antenna arrays

An approximate analytical method is presented, which allows calculation of the transient field strength of linear antenna arrays. The detailed investigation of a logarithmicperiodic dipole antenna on the base of different degrees of approximation shows the separate influence of the element radii and the transient mutual coupling between neighbouring elements. For a better physical understanding of its transient radiation process the cylindrical linear antenna when excited by a step-function with finite rise time is discussed in detail presenting an extension of a recently published approximate version of the Singularity Expansion Method to nonzero center-loading. Dedicated to Professor H. Lueg (RWTH Aachen) on the occasion of his 65th birthday (30 April 1979)