Laser polarimetry of the orientation structure of bone tissue osteons

A matrix method is proposed for describing polarization properties of biological tissues as an aggregate of uniaxial crystal structures. We investigated 25 μm-thick histological sections of compact bone tissue which provided single light scattering. It is shown that in this case there exists a unique relationship between the polarization parameters of the boundary laser field and the parameters of anisotropy and orientation of the structural elements of biological tissue. On this basis, contactless methods of laser polarimetry of histological sections of bone tissue have been proposed. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 52–55, January–February, 2000.     

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.     

Intermolecular interactions in rifabutin–2-hydroxypropyl-β-cyclodextrin–water solutions,according to solubility data

The formulations of rifabutin (RB) and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), obtained using different preparation techniques, are studied by means of differential scanning calorimetry and molecular spectroscopy (FTIR, NMR, Raman scattering, and photon correlation light scattering). It is established that molecules of RB do not form inclusion complexes with the molecules of HP-β-CD, and an increase in the solubility of RB determined earlier is caused by the formation of weak intermolecular associates.     

Synthesis of the C12-C19 fragment of (+)-peloruside A through a diastereomer-discriminating RCM reaction

[reaction: see text]. A short and efficient asymmetric synthesis of the C12-C19 fragment of the cytotoxic macrolide (+)-peloruside A has been achieved via a highly diastereomer-discriminating RCM of alpha-branched but-3-enoate ester of a methallylic alcohol derived from hydrolytically resolved (S)-(-)-propylene oxide.     

Synthesis of C-methyldesoxy sugars: Desoxygenation of tertiary alcohol xanthogenates and hydrozirconation of exomethylene derivatives of carbohydrates

Conclusions Two methods for the synthesis of C-methyldesoxy-sugars were proposed by desoxygenation of tertiary alcohol xanthogenates and hydrozirconation of exomethylene derivatives of carbohydrates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No, 2, pp. 441–445, February, 1986.     

Profile of Molecular Species of Triacylglycerides from the Sea Cucumber Apostichopus japonicus

Chemistry of Natural Compounds - The Apostichopus japonicus (Selenka) is the most valuable commercial species of sea cucumbers. The profile of triacylglycerides (TAG) from the body wall of the sea...