Synthesis of unsymmetrical 2-(2-vinyl-4H-chromen-4-ylidene)malononitrile dyes via Knoevenagel reaction

A series of new chromophores based on 4-(dicyanomethylene)-2-vinyl 4H-chromenes was synthesized and their physical properties (UV–Vis, NMR, mass spectrometry) were studied. The chromophores show moderate or good solubility in organic solvents. Solvatochromism was investigated for compounds in solvents of low (1.4-dioxane, chlorobenzene, methylene chloride) and high polarity (acetone, acetonitrile). The calculations of the first hyperpolarizability (β) was performed using M052X/6-31+G(d) approximation. Chromophore’s molecules are characterized by high calculated values of the first hyperpolarizability (β) that is only 15% lower than that of FTC analogs.     

离子选择电极法测定胶团的反离子结合度

胶团的反离子结合度(K)对于胶团各种性质的研究是一个至关重要的参数^[1～3]。已有不少方法用于K值的测定,其中以离子选择电极法最为方便^[4～8],且此法赋予K值的含义也与热力学要求相同^[9]。     

New synthesis of estradiol from androsta-1,4-diene-3,17-dione

A new method for the aromatization of ring A in androsta-1,4-diene-3,17-dione, available from sterols by means of the microbiological degradation of the side chain, was developed. The method consists of the reduction of androsta-1,4-diene-3,17-dione to the corresponding dienediol followed by double C,O-deprotonation of ring A, accompanied by expulsion of the 19-methyl group and formation of estradiol in a high yield. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 599–601, March, 1999.     

Phase composition and the micro- and macrostructures of quasi-crystalline powders obtained by plasma-chemical synthesis

Quasi-crystalline Al₆₅Cu₂₃Fe₁₂ powders have been obtained by the method of plasma-chemical synthesis. Coarse particles have a spherical form and an inhomogeneous structure because of the laminar growth of crystallites toward the surface of the particles. The influence of heat treatment on phase formation and structuring in Al–Cu–Fe alloys has been studied. It has been found that the heat treatment of as-prepared powders changes the phase relationship in the quasi-crystalline alloy.     

Analysis of the interrelation between the processes of polarization and microstructuring in a magnetic fluid layer

The results of examining and analyzing the interrelation between the processes of polarization and structuring in magnetic fluid microlayers under the influence of the temperature, external electric and magnetic fields, and variations in the structure and amount of stabilizer have been presented.

     

Analysis of biomedical signals by flicker-noise spectroscopy: Identification of photosensitive epilepsy using magnetoencephalograms

The flicker-noise spectroscopy (FNS) approach is used to determine the dynamic characteristics of neuromagnetic responses by analyzing the magnetoencephalographic (MEG) signals recorded as the response of a group of control human subjects and a patient with photosensitive epilepsy (PSE) to equiluminant flickering stimuli of different color combinations. Parameters characterizing the analyzed stochastic biomedical signals for different frequency bands are identified. It is shown that the classification of the parameters of analyzed MEG responses with respect to different frequency bands makes it possible to separate the contribution of the chaotic component from the overall complex dynamics of the signals. It is demonstrated that the chaotic component can be adequately described by the anomalous diffusion approximation in the case of control subjects. On the other hand, the chaotic component for the patient is characterized by a large number of high-frequency resonances. This implies that healthy organisms can suppress the perturbations brought about by the flickering stimuli and reorganize themselves. The organisms affected by photosensitive epilepsy no longer have this ability. This result also gives a way to simulate the separate stages of the brain cortex activity in vivo. The examples illustrating the use of the “FNS device” for identifying even the slightest individual differences in the activity of human brains using their responses to external standard stimuli show a unique possibility to develop the “individual medicine” of the future.     

Measurement of inertial microaccelerations with the use of convection sensors

The influence of external seismic actions on the convective flows in a Hele-Shaw cell heated from below is investigated theoretically. The temperature and velocity fields and the patterns of flows are calculated in the cases of the detection of vertical and horizontal seismic signals. The results of the calculations will be used in the design of an instrument for detecting microaccelerations of seismic origin. The working fluid is chosen and the optimum geometric parameters of the cavity of the convection sensor are determined using numerical simulation.     

Device for Increasing the Magnetic Flux Pinning in Granular Nanocomposites Based on the High-Temperature Superconducting Ceramic

A device for modifying the granular high-temperature superconducting ceramics in the plasma of a low-pressure arc discharge has been considered. The particular features of the design and operational principle of this device have been described. The device made it possible to combine the synthesis of that play a role of additional pinning centers and simultaneous deposition of these nanoparticles on microgranules in a single processing cycle. The experimental results on the effect of additional pinning centers on an increase in the critical current thanks to the formation of self-assembled structures in the form of whiskers have been considered.