Asymmetrical flow field-flow fractionation as a novel technique for the analysis of PS-b-PI copolymers

Asymmetrical flow field-flow fractionation (AF4) was used as a fractionation technique to investigate the molecular heterogeneity of poly(styrene-b-isoprene) diblock copolymers synthesized by either sequential living anionic polymerization or coupling of living precursor blocks. AF4 coupled to multi-angle laser light scattering (MALLS), refractive index (RI), and ultraviolet (UV) detectors was used to separate the diblock copolymers from the homopolymers and coupling products, and the molar masses of the different components were analyzed. In order to get more information about the separated block copolymers, homopolymers, and coupling products, fractions were collected directly after the AF4 channel. The collected fractions were analyzed offline by ¹H NMR to provide identification of the different species and additional information on the true chemical composition, and the microstructure of the diblock copolymer was obtained.

Quantitative structure-affinity relationship of 5-HT1A receptor ligands by the classification tree method

The influence of molecular structure of 346 ligands on their affinity for 5-HT1A receptors was investigated. It was shown that the effectiveness of the proposed novel approach for interpretation of decision tree models compared favourably with the PLS method. In the context of the proposed approach, molecular fragments and their values of the relative influence on the affinity for 5-HT1A receptors were defined.     

Morphology-dependent photonic circuit elements

We theoretically propose and experimentally demonstrate the design of a novel one-dimensional ringlike macroscopic optical circuit element. The similarity between morphologies of an optical planar waveguide and a whispering-gallery axially symmetric solid-state resonator is used.     

Synthesis and structure of 3-arylidene and 3-hetarylidene-1,2-dihydro-3H-1,4-benzodiazepin-2-ones and their affinity toward CNS benzodiazepine receptors

The condensation of 5-aryl-7-bromo-1,2-dihydro-3H-1,4-benzodiazepin-2-ones with aromatic aldehydes gives 5-aryl-3-arylidene-and 5-aryl-7-bromo-3-hetarylidene-1,2-dihydro-3H-1,4-benzodiazepin-2-ones. X-ray diffraction structural analysis yielded the molecular and crystal structures of 7-bromo-3-(4′-methoxybenzylidene)-5-phenyl-1,2-dihydro-3H-1,4-diazepin-2-one and showed that this compound has cis configuration. Radioligand analysis was used to study the affinity of these products toward central nervous system and peripheral benzodiazepine receptors. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1213–1225, August, 2007.     

Low threshold optical oscillations in a whispering gallery mode CaF(2) resonator

We have observed low-threshold optical hyperparametric oscillations in a high-Q fluorite whispering gallery mode resonator. The oscillations result from the resonantly enhanced four-wave mixing occurring due to Kerr nonlinearity of the material. We demonstrate that, because of the narrow bandwidth of the resonator modes as well as the high efficiency of the resonant frequency conversion, the oscillations produce stable narrow-band beat-note of the pump, signal, and idler waves. A theoretical model for this process is described.     

Monitoring extracted beams of the nuclotron accelerator complex for “energy + transmutation” experiments

A monitoring system for measuring absolute intensity and the space—time structure of extracted beams of Nuclotron based on ionization and activation methods has been created and tested. The monitoring system provides a measurement of the absolute intensity of extracted beams with a precision of 10% and beam position with a precision of 0.5 mm.     

Analytical investigation of simultaneous effects of convergent section heating of Laval nozzle,steam inlet condition,and nozzle geometry on condensation shock

Rapid expansion and supercooling of dry vapor in low-pressure steam turbines trigger nucleation phenomenon. Subsequently, following the occurrence of vapor condensation, a vapor–liquid two-phase flow is established. Entropy generation mainly by condensation shock, blade erosion, and ultimately, destruction of equipment and efficiency reduction are among adverse effects of vapor condensation, which should be either attenuated or controlled. In the present research, which is a continuation to the research performed by original authors, a one-dimensional analytical Eulerian–Lagrangian model is used to apply convergent section heating to different supersonic nozzles under various inlet conditions. The results indicate that the flow response to the heating is well dependent on the intensity of condensation shock or inlet conditions. In order to compensate for the mass flow rate resulted from the convergent section heating, effects of simultaneous reduction of inlet stagnation temperature and convergent section heating were investigated. Finally, it was found that, maintaining constant mass flow rate, simultaneous reduction of inlet stagnation temperature and convergent section heating cannot attenuate the condensation shock significantly. Therefore, the best approach to compensate for the reduction in the mass flow rate due to convergent section heating is to simultaneously increase inlet stagnation pressure.     

Methods for rapidly altering the permeability of mammalian cells.

Various agents alter mammalian cells so that they rapidly become nonspecifically permeable to substances that ordinarily do not penetrate intact cells. Thus, toluene renders liver cells permeable to nucleotides and macromolecules. Tween 80 and Tween 60 act on similar fashion, and the effect is reversible. Dextran sulfate reversibly alters the permeability of Ehrlich ascites tumor cells, which offers a tool for studying the control of macromolecular syntheses and other processes. Brief exposure to external ATP alters the permeability of certain transformed mouse cells but not of untransformed cells. The effect of ATP is rapidly reversible.