On the possibility of a unified approach to investigating the indicatrices of coherent wave scattering by different inhomogeneities of the medium

A general expression describing the coherent scattering indicatrix by arbitrary inhomogeneities of the medium is derived. It is shown that a universal program can be devised for calculation of such indicatrices to avoid difficulties in the analytical and experimental investigations of the media through the wave processes.Institute of Applied Geophysics, Moscow. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 7, pp. 631–638, July, 1995.     

Monte Carlo simulations in the vicinity of the critical point: Vapour-liquid coexistence curve

A generalized Gibbs-ensemble methodology with a fluctuating particle is used to determine the coexistence vapor-liquid densities for a square-well fluid. It is shown that the presence of the fluctuating particle in sub-states of the Markov chain of states supresses considerably density fluctuations which makes it possible to carry out simulations efficiently even for temperatures very close to the critical temperature.     

Spinor norms of local autometries of generalized quadratic lattices

It is proved that the group of spinor norms of autometries of a generalized quadratic lattice ℒ over the ring of integral elements v _p of a local field k _p , in the case wherep∤2 and ℒ is a generalized translation, is generated by the spinor norms of symmetries contained in the group of autometries of ℒ. As a corollary, an extension to the case of generalized quadratic lattices is given for known sufficient conditions of coincidence of the genus and the spinor genus of a quadratic lattice. Bibliography: 9 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 211, 1994, pp. 161–173. Translated by Yu. G. Teterin.     

Hyperbolic stefan problem in a curvilinear sector

The problem with unknown boundaries for a first-order semilinear hyperbolic system is studied in the case where the curve of definition of the initial conditions degenerates to a point. An existence and uniqueness theorem for a classical solution of the problem is proved for small t.     

Contributions to the synthesis of some ferrocene-containing antibiotics

This Review discusses the synthesis and characterization by our Group of new antibiotics belonging to the class of penicillins, cephalosporins and rifamycins with ferrocenyl and 1, 1′-ferrocenilene residues in the molecule. As reactants for 6-aminopenicillanic acid (6-APA) and 7-aminocephalosporanic acid (7-ACA) the following were used: 1, 1-bis(chlorocarbonyl)ferrocene, ferrocenyl sulfochloride, 1, 1′-ferrocenylenedisulfochloride and thioglycolic acids S-modified with ferrocene. In the synthesis of rifamycins, the hydrazides of the thioglycolic acids, S-modified with ferrocene, were employed as nucleophilic agents. The synthesized intermediates were characterized by elemental analysis, TLC, IR, UV and ¹H NMR spectra. The characterization of new antibiotics was made by TLC, IR and UV spectral analysis. Biological activity was tested on Gram-negative and Gram-positive bacteria. Good activity is reported towards Gram-positive bacteria in the case of derivatives containing residues of thioglycolic acid S-modified with ferrocene, the antibacterial activity being similar to that of amoxicillin, carbenicillin and cephalothin. All compounds are inactive towards Gram-negative bacteria.     

Thermoluminescence of KMgF3(RE) crystals

Optical properties of pure and RE doped KMgF₃ crystals were studied. Thermoluminescence curves are independent of the introduced impurity for all dopant besides europium. Emission, radiation damage and TL are found to be significantly dependent on the types of Eu-dopant added to the melt: europium fluoride or oxide. An intensive high temperature TL peak at 390°C in KMgF₃(Eu₂O₃) may be used as a dosimetric one not only for ionizing but also for UV radiation.     

Electron tuning of frequency in gyrotrons

Formulas for shifts of gyrotron autooscillation frequency due to change of electron beam parameters are presented. The frequency shifts can be commensurable with the frequency band of the beam-unloaded cavity. The autooscillation frequency is most sensitive to the change of the magnetic field, less to the change of the anode voltage and least to the the change of the beam voltage. Experiments presented are in satisfactory agreement with the theory.The authors wish to thank M.I. Petelin for his interest to the present work.     

Plant polysaccharides I. Polysaccharides ofLagochilus and their biological activity

Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 313–314, March–April, 1995. Original article submitted November 7, 1994.