Chrysin and its derivatives in plants of the genusScutellaria

Summary 1. A glycoside (II) identified by chrysin 7--glucopyranosiduronic acid has been isolated from the epigeal part ofScutellaria scordiifolia in a yield of 2.0–2.2%.2. A glycoside (IV), characterized as 2-methoxychrysin 7--D-glucopyranosiduronic acid has been isolated from the roots ofS. granulosa.3. This is the first time that chrysin and 2-methoxychrysin and their 7-glucuronides have been isolated from theScutellaria species mentioned.Khar'kov Scientific-Research Institute of Pharmaceutical Chemistry. Ukrainian Zonal Research Station for Medicinal Plants, Poltava. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 730–735, November–December, 1976.     

Transport damping by fluctuations and cluster-type expansions in kinetics

A mechanism of transport damping by fluctuations is proposed and analyzed in detail for the thermal diffusivity of a one-dimensional gas in the case when the externally induced temperature gradient is weaker than fluctuating gradients. Thermal diffusivity is calculated as a function of parameters of a one-dimensional gas characterized by a homogeneous potential of interaction between particles: for the potential V(x)=Q/|x|^k, thermal diffusivity is χ ∼ (Qn ^k/T)^1/(k−1)ν_T/n. The nonanalytic form of thermal diffusivity as a function of concentration is elucidated. The nonanalytic behavior of thermal diffusivity as a function of concentration is explained by a nontrivial symmetry of the problem under analysis at long times, after the initial fluctuations have dissipated. It is shown that spontaneous generation of macroscopic structures developing through selective growth of fluctuations of a certain type in a medium with an externally induced temperature gradient controls the transport properties of the medium when k≈1.     

High-power mid-IR (4–5 μm) femtosecond laser system with a broadband amplifier based on Fe<Superscript>2+</Superscript>:ZnSe

Concept of a solid-state femtosecond laser system with a multigigawatt power level in the 4–5 μm range has been proposed. The system contains an ultrashort pulse seeder, a two-stage chirped pulse amplifier based on a broadband Fe²⁺:ZnSe active element with optical pumping by a YSGG:Cr:Er laser, and an output stage that provides additional nonlinear optical compression of an amplified pulse to approximately 30 fs in a dielectric CaF₂ medium with anomalous group velocity dispersion in this spectral range.     

Interference immunity of hydroacoustic power flux receive systems

Based on an analysis of experimental data and model simulations, the potential of small-size vector hydroacoustic receive systems measuring acoustic power flux (APF) are discussed in application to the detection of weak signals in the presence of ambient sea noise. It is shown that APF receivers are capable of measuring signal levels no less than 10–20 dB lower (depending on the signal-interference situation in the water area) than those measured by PRs. In order to extend the class of hydroacoustic systems whose potential can be correctly compared, it is proposed to modify the definition of interference immunity by introducing two separate qualifying notions: noise and interference.