Erratum to: “The Fluorescence and Electronic Structure of Phenyl-Substituted Tetraazachlorin Molecules” [Optics and Spectroscopy 117, 722 (2014)]

Optics and Spectroscopy - should read “porphyrazine” instead of “porphyrazin”; should read “intersystem crossing” instead of “intercombinational...     

Astrophysical <Emphasis Type="Italic">S</Emphasis>-factor of T(<Superscript>4</Superscript>He, γ)<Superscript>7</Superscript>Li reaction at <Emphasis Type="Italic">E</Emphasis><Subscript>cm</Subscript> = 15.7 keV

The astrophysical S-factor of the reaction T(⁴He, γ)⁷Li is measured for the first time at the center of mass energy E _cm = 15.7 keV, lower than the energy range of the Standard Big Bang Nucleosynthesis (SBBN) model. The experiment is performed on a Hall pulsed accelerator (TPU, Tomsk). An acceleration pulse length of 10 μs allows one to suppress the background of cosmic radiation and the ambient medium by five orders of magnitude. A beam intensity of ~ 5 × 10^{14 4}He⁺ ions per pulse allows one to measure an extremely low reaction yield. The yield of γ-quanta with the energies E _γ ⁰ = 2483.7 keV and E _γ ¹ = 2006.1 keV is registered by NaI(Tl) detectors with the efficiency ε = 0.331 ± 0.026. A method for direct measurement of the background from the chain of reactions T(⁴He, ⁴He)T→T(T, 2n)X→(n, γ) and/or (n, n′γ) which ends by neutron activation of materials surrounding the target is proposed and implemented in this study. The value of the astrophysical S-factor of the reaction T(⁴He, γ)⁷Li S _αt (E _cm = 15.7 keV) = 0.091 ± 0.032 keV b provides the choice from the set of experimental data for the astrophysical S _αt -factor in favor of experimental data [4] with S _αt (E _cm = 0) = 0.1067 ± 0.0064 keV b.     

The fluorescence and electronic structure of phenyl-substituted tetraazachlorin molecules

The effect of the addition of phenyl groups to pyrrole rings of tetraazachlorins, a new class of tetrapyrroles, on the photophysical properties and electronic structure of the molecules has been investigated by a complex of experimental and theoretical methods. Characteristics of fluorescence at 293 and 77 K have been determined for phenyl-substituted tetraazachlorins. The objects of this study include unsubstituted tetraazaporphine. The introduction of phenyl groups affords a marked increase in the fluorescence quantum yield. For tetraazaporphine and phenyl-substituted tetraazachlorins, fluorescence buildup occurs as the temperature is decreased from 293 to 77 K, but to a lesser extent than for tetraazachlorins having no phenyl groups, which were earlier studied by the authors. The fluorescence buildup mechanism is discussed. The singlet oxygen generation quantum yield has been determined for the tetrapyrroles examined. This characteristic increases upon tetrapyrrole is phenylation. The electronic structure and absorption spectra of unsubstituted porphine and chlorin, tetraazaporphine, tetraazachlorin, octaphenyltetraazaporphine, and tetramethylhexaphenyltetraazachlorin have been calculated by the INDO/Sm method (original modification of the INDO/S method) with molecular geometry optimization using DFT. The results of the quantum-chemical calculation of the absorption spectra are in good agreement with experimental data for transitions to the lowest excited electronic states Q _x (S ₁) and Q _y (S ₂).     

Bioisosteric equivalence of five-membered heterocycles

A variety of factors can affect bioisosteric relationships between structural motifs in a medicinal chemistry optimization project, both in terms of ligand affinity to a given target and off-target profile. Such parameters, e.g. the ability to participate in hydrogen bonding and π–π interactions, basicity, and solubility are discussed with a particular focus on five-membered heterocycles and their application in drug design.     

Ranges of 0.2-1.0 GeV/nucleon heavy ions in nuclear photoemulsion

Heavy nuclei transport in matter are studied experimentally and theoretically. Our experimental range and straggling values of 0.2 – 1.0 GeV/nucleon ²⁰Ne, ⁴⁰Ar, ⁵⁶Fe, ¹⁹⁷Au and ²³⁸U nuclei in BR-2 nuclear photoemulsion are presented and compared with model calculations carried out according to our RANGE-program and the PRAL-model (version of 1987) developed by Ziegler et al. The presented data analysis points at the necessity to take into account Z³-correction in Bete-Bloch formula when ionization losses of very heavy multicharge ions (for example ¹⁹⁷Au and ²³⁸U) are calculated. The comparison of experimental and calculated results showed that RANGE program can correctly calculate the ranges and straggling of heavy ions. The difference between experimental and theoretical data do not exceed 5% in all of the cases examined. PRAL model describes the heavy ion ranges quite adequately, but overestimates the particle range straggling.     

Effect of addition of water vapor on the operation of a chemical CO laser

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 50, No. 4, pp. 600–604, April, 1989.     

Structure of a glucuronoxylan of the stems ofSymphytum asperum

The results are given of an investigation of the structure of a glucuronoxylan of the stems ofSymphytum asperum Ler. The xylan was isolated by alkaline extraction and was purified by reprecipitation via the copper complex. The polysaccharide was homogeneous according to the results of gel filtration and electrophoresis. It was shown by hydrolysis, periodate oxidation, methylation, oxidation with chromium trioxide and IR and¹³C NMR spectroscopy that the macromolecules were based on a -(14)-polyxyloside chain having side chains at the second carbon atoms in the form of 4-O-Me-D-glucuronic acid. To each side chain there were not less than 12 xylose residues.M. V. Lomonosov Technological Institute of the Food Industry, Odessa. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 478–481, July–August, 1985.     

Oxidative Ammonolysis of Birch Wood

The functional composition of oxidative ammonolysis products obtained from treatment of birch wood with ammoniacal ammonium persulfate using a mechanochemical method was studied.     

Variations in Acid-Base Properties of Kaolinite upon Mechanical Treatment

The pK spectra of kaolinite of the Puzlinsk deposit (Komi Republic) mechanically activated in centrifugal planetary mills are obtained. It is shown that even a short mechanical activation of kaolinite is accompanied by significant changes in its structure as demonstrated by variations in the pK spectra of kaolinite and by an increase in its exchange capacity.