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Contemporary BSIM- and EKV-type MOSFET models are very complicated. Therefore, their identification is a quite difficult task from both algorithmic and numeric points of view. In the paper, we outline several modifications of a classical procedure which enable reliable identifications of various types of these models.

At present, most of simulation programs can characterize gate delays of microwave transistors. However, the delay is mostly approximated by means of a first-order differential equation only. In the paper, a more accurate way is suggested which is based on an appropriate second-order Bessel function. The delay model is implemented to a slightly but efficiently modified classic MESFET model. The proposed model does not create spurious oscillations that are typical for any LC approximations, and the simulation times are comparable with those obtained without the delay model. Properties of the implementation of the second-order Bessel function are demonstrated by an analysis of a tunable distributed microwave oscillator.

Nowadays, there are miscellaneous types of high frequency devices for which their models for CAD are necessary. However, in the majority of standard programs for RF design, only a class of MESFET models is available. These models are sufficiently accurate for usual devices; however, they are insufficiently accurate for modeling special high frequency devices. In paper, a method is proposed for modeling the special devices using exclusive or corrective artificial neural networks.

Nowadays, there are many various microwave structures for which their nonlinear models for CAD are necessary. However, in the recent PSpice family programs, only a class of five types of MESFET model is available. In the paper, a way is suggested for modeling miscellaneous microwave structures by exclusive neural networks, or corrective neural networks working attached to an updated analytic model. The accuracy of both procedures is assessed by extracting model parameters in static and dynamic domains: first, an approximation of the AlGaAs/ InGaAs/ GaAs pHEMT output characteristics is carried out by the corrective neural network; and second, an approximation of the capacitance function of the InGaAs/ InP avalanche photodiode is performed by the exclusive neural network. A sequence of analyses is also performed for determining optimal structure of the artificial neural network.

Tris-2,2′-bipyridine complexes of Co(II), Ni(II), and Fe(II) and a bis-2,2′,2″-terpyridine complex of Co(II) in aqueous perchlorate media were studied by means of electrode double-layer capacitance measurements at the hanging mercury drop electrode. At potentials where no faradaic process takes place all compounds form two types of compact films with different orientations of species at the interface. The solid-like nature of these films was confirmed from the hysteresis of capacitance vs. potential curves and from the sigmoidal Avrami-type capacitance vs. time dependence. As a new feature of the nucleation/growth process, long-time deviations from the Avrami shapes were found. At potentials where the nucleation rate is very small, the C—t curves exhibit an S-shape, followed by a maximum usually at time s $ 1000 s. An interpretation in terms of a change from 2D- to 3D-type growth is suggested.

The rate of disproportionation of uranium(V) was studied at a hme using single sweep and cyclic voltammetry in sulphate solutions at an almost constant ionic strength (I = 1.2-1.0 mol1−1) as a function of pH and concentration of uranium(VI). The rate constant of disproportionation of uranium(V) in 0.4 M Na2SO4 recalculated for the activity of hydrogen ion equal unity is k0 = 6.3 × 105 mol−212s−1. Also standard rate constants ks were determined. In preliminary dc polarography experiments in other complexing media as citrate, tartarate and oxalate a higher increase of the limiting current than in sulphate was found for the same pH values pointing to the assumption that in these media the disproportionation reaction of uranium(V) might proceed still faster than in sulphate solutions.

By means of biotyping we have investigated 150 strains of Staphylococcus aureus isolated from people with dermatologic complaints. We have used six main and three additional biotyping tests. The strains under investigation did not form a closed biotype, on the contrary, they showed a certain biotype plurality. The determination of protein A in 150 strains of S. aureus isolated from dermatologic process of men, 15 strains of S. aureus of bovine origin and 50 strains of Staphylococcus with negative coagulase activity have brought the following results: all strains of S. aureus of skin origin (human strains) contain protein A in various quantities keeping within 2-64 U. Only 2 from 15 s. aureus strains of bovine origin contain protein A and there were none in 50 strains of Staphylococcus with a negative coagulase reaction.

From 1971 to 1976 the author examined by cultivation on Sabouraud glucose agar, 1720 specimens of the most varied materials--skin scales, nails, hair, beard, sputum--obtained from patients suffering from skin problems. In no one single case did he find Candida pulcherrima. However, since 1977 he has found C. pulcherrima to be on an increase. From 1977 to 1984 in 4644 specimens C. pulcherrima was found in 44 cases. 38 strains, i.e. 86%, were isolated from patients with clinical diagnosis of mycotic infection. The most frequent diagnosis was onychomycosis, 36%. Cultivation findings were mostly profuse and massive relative to the number of germs, in some patients even occurring repeatedly. In view of these findings it may be necessary to revise the views purporting the finding of C. pulcherrima from human material to be insignificant.

Die Geschwindigkeit der Disproportionierung von U(V) in U(VI) und U(IV) in 0.4 M NazSOrLosung wird in Abhangigkeit vom pH bestimmt.