Conformational characteristics of polycaproamide in dimethylacetamide containing lithium chloride

The viscosity behavior, index of refraction, and density of dilute polycaproamide solutions in DMAc containing lithium chloride have been studied. On the basis of temperature dependences of the index of refraction and the density of solutions, the θ-condition of polycaproamide solutions in DMAc containing 2.5% lithium chloride is estimated as 21.3°C. From intrinsic viscosity [η] measurements, the coefficients of swelling of a polymer coil, the mean-square distance between chain ends, and other parameters of macromolecules in solution are calculated.     

Algorithm for nonlinear digital filtering of harmonic filling of phase-shift keyed signals

In this work, we propose a method for nonlinear digital filtering of phase-shift keyed signals with different carrier frequencies on the basis of separating the phase discontinuities of the input signals. The method allows one to avoid compensation for unknown frequency shift in the problems of determining the time delay of signals in the case of multichannel propagation. The efficiency of the proposed method is shown for the signals which are short informative packages with the phase-shift keying against the noise background in the presence of the Doppler effect. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 8, pp. 704–711, August 2006.     

The Inclusion Mode of tert-Butylbenzene in the 1-D Channel of Microporous β-Bis(1,1,1-trifluoro-5, 5-dimethyl-5-methoxy-acetylacetonato) copper(II)

Inclusion of tert-butylbenzeneinto the l-D channel of the titlehost matrix results in a-[CuL₂]1/3(tert-butylbenzene)inclusion compound(trigonal, space groupR =3;a = 24.495(3),c = 10.510(2) Å,V = 5461(1) ų,Z = 9;R = 0.049). The observed guest–host mole ratio of 1/3 was confirmed by X-ray diffraction and arises from the stoichiometric filling of the larger wide segments of the channel. This contrasts with the benzene inclusion compound studied previously, where both the larger and smaller wide segments were occupied to give a 2/3 guest–host stoichiometry. A comparison of these two structures explains the experimental fact that the guest–host mole ratios for inclusions of the title host lie between values of 1/3 and 2/3for 20 different benzene derivatives.     

Methyl <Emphasis Type="Italic">tert</Emphasis>-Amyl Ether Synthesis Catalyzed by a Sulfonic Cation Exchanger: The Effect of the Degree of Hydration of the Cation Exchanger on the Catalytic Activity and Reaction Mechanism

The catalytic properties of the fibrous sulfonic acid cation exchanger FIBAN K-1 in methyl tert-amyl ether synthesis are studied as a function of its water content. Reducing the degree of hydration of the cation exchanger to <2 H₂O molecules per SO₃H group diminishes the proportion of the desired product in the catalysate. According to ¹³C NMR data, protonation of methylbutenes in the air-dry cation exchanger phase (which contains 4 H₂O molecules per SO₃H group) involves [nH₂O] ⋅ H⁺ species and is accompanied by olefin hydration and the formation of protonated tert-amyl alcohol.__________Translated from Kinetika i Kataliz, Vol. 46, No. 4, 2005, pp. 536–542.Original Russian Text Copyright © 2005 by Egiazarov, Soldatov, Tychinskaya, Shachenkova, Cherches, Ermolenko.     

On the spectral radius of functional operators

An estimate of the spectral radius of functional operators generated by operators of multiplication and shift operators in the space of continuous vector functions on the interval is given. It is assumed that shifts have fixed points only at both ends of the interval and belong to one type, i.e., they are either left or right shifts.     

Cherenkov counter for measuring the intensity of bunches extracted from the IHEP accelerator

The Cherenkov counter for measuring the numbers of protons in bunches extracted from the IHEP accelerator using a slow extraction system is described. The measurement range is from 1 to 10⁶ particle/bunch. The maximum bunch frequency is 6 · 10⁶ s^–1. Cherenkov light is measured by an XP 2020 photomultiplier. The results of measurements of the XP 2020 signal amplitude on the applied voltage, obtained using semiconductor light sources are presented. The data of counter calibration on the proton beam are discussed.     

The first representative of a new class of charge transfer complexes in o-quinone series for organic semiconductors

The first representative of a new class of charge transfer complexes for organic semiconductors was synthesized. The reaction of p-nitroaniline (PNA) with [1,10]-phenanthroline-5,6-dione (PD) results in the formation of a stable molecular charge transfer (CT) complex PNA₃-PD₂ in a ratio of 3:2. The structure of the molecular CT complex PNA₃-PD₂ was established by X-ray diffraction studies. Using the density functional theory method, it is shown that several types of intermolecular interactions are realized in the complex: between the PNA amino group and the nitro group of another PNA molecule, carbonyl groups, and PD nitrogen atoms. Complex PNA₃-PD₂ is stable only in solid form. The diffuse reflectance UV–vis spectrum of PNA₃-PD₂ crystal powder is characterized by the intense weakly structured long-wavelength absorption band up to 650 nm. Quantum chemical calculations of the electronic structure have shown that the complex PNA₃-PD₂ is a straight-band semiconductor with a band gap of 2.11 eV.