Relative equilibria of a massive point on a uniformly rotating asteroid

The motion of a massive point (a bead) over the surface of a uniformly rotating asteroid is considered. It is assumed that the force of dry friction acts between the point and the asteroid surface. The sets of nonisolated positions of relative equilibrium of the bead on the asteroid are described, and their dependence on the parameters of the problem is investigated. The results are presented as bifurcation diagrams.     

Quantum chemical studies of the oxidative alkylamination of diazinones

The B3LYP/6-31G** quantum chemical method was used to study the mechanism of the oxidative alkylamination of diazinones taking 1,3,6-trimethylpyrimido[4,5-d]pyrimidine-2,4,7(1H,3H,6H)-trione (lumazinone) as an example. The first limiting step of this reaction included a nucleophilic addition of alkylamine with the formation of the σ^H-adduct, which was oxidized by potassium permanganate in the second step. The alkylamination step proceeded in the associates formed by the lumazinone dimer and several alkylamine molecules involved in both the nucleophilic attack and the bifunctional catalysis of the process. The correlation of the Parr indices with the experimental data was studied for a number of diazinones.     

Covariant Relativistic Separable Kernel Approach for Electrodisintegration of the Deuteron at High Momentum Transfer

The paper considers the electrodisintegration of the deuteron for kinematic conditions of the JLab experiment E-94-019. The calculations have been performed within the covariant Bethe?CSalpeter approach with a separable kernel of nucleon?Cnucleon interactions. The results have been obtained using the relativistic plane wave impulse approximation and compared with experimental data and other models. The influence of nucleon electromagnetic form factors has been investigated.     

The first 13-vinyl derivatives of berberine: synthesis and antimicrobial activity

Chemistry of Heterocyclic Compounds - A method for the synthesis of berberine 13-vinyl derivatives has been developed consisting of an initial reaction of triethyl orthoformate with CH acids in the...     

Accurate measurement of the cutoff wavelength in a microstructured optical fiber by means of an azimuthal filtering technique

A simple self-referenced nondestructive method is proposed for measuring the cutoff wavelength of microstructured optical fibers (MOFs). It is based on the analysis of the time-dependent optical power transmitted through a bow-tie slit rotating in the far-field pattern of the fiber under test. As a first demonstration, the cutoff wavelength of a 2 m MOF sample is found to be close to that provided by numerical predictions (approximately 25 nm higher). Because of the high dynamics of the measurement, the uncertainty is limited to Dlambda= +/-10 nm.     

A sensitive 3–4-mm radiometer

Improving the parameters of the Schottky barrier mixing diodes has permitted us to improve the sensitivity of the 3–4-mm radiometer described in [1]. The authors were able to achieve a fluctuation sensitivity of no worse than 0.15K for double-sideband reception with an output RC filter time constant of =1 sec by using, with several changes, the high-frequency part of this receiver. The sensitivity reached 0.1K at several points in the 3–4-mm range. Figure 1 shows a calibration record of a standard load, cooled in liquid nitrogen. The amplification while recording the noise was 30 times greater than for the calibration signal.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 21, No. 11, pp. 1702–1703, November, 1978.     

Synthesis and investigation of the antitumoral activity of shortened analogs of luliberin

With the aim of obtaining antitumoral drugs possessing a binary action mechanism, we have synthesized a series of shortened analogs of luliberin, including some containing a 1-carboxymethyl-5-fluorouracil residue. Their antitumoral and hormonal activities have been investigated.Institute of High-Molecular-Mass Compounds, Russian Academy of Sciences, St. Petersburg. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 655–662, September–October, 1994.     

Acoustic tomography of the nonlinear parameter by a small number of transducers

A wave approach to solving the problem of reconstructing the acoustic nonlinear parameter distribution by a simple transmitting-receiving system with broadband modulation of primary waves is proposed. The approach uses the effect of sound scattering by sound, which makes it possible to employ a complicated time processing of signals instead of spatial processing and, consequently, to reduce the number of transmitting and receiving transducers. The possibility of practical implementation of a two-dimensional tomographic scheme based on coherent correlation processing of broadband quasi-random signals at combination frequencies is analyzed. Results of model numerical experiments on reconstructing complicated spatial distributions of the nonlinear parameter are presented.