Characteristics of nonlinear reflection of radiation associated with waverfront reversal by a surface

The dependence of the nonlinear reflection coefficient R of a mirror with a wavefront reversing surface on the intensity I of the reference wave is analyzed in terms of a phenomenological model of a medium having a nonlinear Fresnel reflection amplitude coefficient φ. Substantial differences are revealed for media having different signs of the nonlinearity coefficient β=(dφ/dI). It is shown that R is related to the magnitude D of the dynamic range of the wavefront reversing mirror by the expression RD=Q_s' where Q_s is a parameter which defines the “quality” of the nonlinear medium. Far-Eastern State Academy of Communications. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 68–70, August, 1997.     

Determining the statistical parameters of nonstationary stochastic processes

We construct estimators of the expectation of a nonstationary stochastic process with time-dependent variance. Limit relations are obtained for particular correlation dependences.Translated from Statisticheskie Metody, pp. 98–103, 1982.     

Synthesis of positively charged lipids containing a 1,3-oxathiolane cycle

Positively charged lipids of the 1,3-oxathiolane series were synthesized by interaction of 2-pentadecyl-5-tosyloxymethyl- or -5-iodomethyl-1,3-oxathiolane with 2-(N,N-dimcthyl-amino)ethanol.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2347–2349, September, 1996.     

Using methyl red dye in the analysis of benzodiazepine drugs

The applicability of the spectrophotometric method for the quantitative determination of phenazepam using methyl red as an optical reference sample is demonstrated. The optical parameters of methyl red’s absorption bands and its optimum regions of absorption are confirmed, a scaling ratio is determined, and equations for the calibration curves are proposed.     

Pseudilins: Halogenated,Allosteric Inhibitors of the Non‐Mevalonate Pathway Enzyme IspD

The enzymes of the non‐mevalonate pathway for isoprenoid biosynthesis have been identified as attractive targets with novel modes of action for the development of herbicides for crop protection and agents against infectious diseases. This pathway is present in many pathogenic organisms and plants, but absent in mammals. By using high‐throughput screening, we identified highly halogenated marine natural products, the pseudilins, to be inhibitors of the third enzyme, IspD, in the pathway. Their activity against the IspD enzymes from Arabidopsis thaliana and Plasmodium vivax was determined in photometric and NMR‐based assays. Cocrystal structures revealed that pseudilins bind to an allosteric pocket by using both divalent metal ion coordination and halogen bonding. The allosteric mode of action for preventing cosubstrate (CTP) binding at the active site was elucidated. Pseudilins show herbicidal activity in plant assays and antiplasmodial activity in cell‐based assays.     

Frequency conversion of broadband laser radiation distorted by spherical aberration in uniaxial crystals

Mechanisms of the frequency conversion of broadband infrared laser radiation in a uniaxial crystal with the radiation focused by a lens with spherical aberration are investigated. A mathematical model is presented. Computer modeling of the spatial–angular structures of frequency-converted focused broadband infrared radiation is performed.     

Tunneling of electrons with conservation of the transverse wave vector in the Au/CaF2/Si(111) system

Epitaxial layers of calcium fluoride on silicon(111) have been prepared, in which tunneling transfer of electrons with conservation of the transverse momentum component has been observed. A good agreement between the results of simulation and the experimental data has been achieved. The procedure underlying the calculations has been described in detail. The obtained films are suitable for the use as barrier layers in various solid-state electronic devices.     

On a Spatially Selective Phototransformation Method for Investigation of Diffusion of Quantum Systems

A new method of determining the diffusion characteristics of quantum systems in crystals is investigated in the present paper on the example of color centers. The method is based on a spatially selective photochemical crystal transformation upon exposure to optical radiation pulses. The principal feasibility of implementation of this method for the determination of the diffusion coefficient of color centers based on the observed dynamics of spatially modulated distribution of their concentrations induced by optical radiation with femtosecond coherence is demonstrated.