Liftable homeomorphisms of rank two finite abelian branched covers

Archiv der Mathematik - We investigate branched regular finite abelian A-covers of the 2-sphere, where every homeomorphism of the base (preserving the branch locus) lifts to a homeomorphism of the...     

Enhancement of the Activity and Enantioselectivity of Lipase by Sol–Gel Encapsulation Immobilization onto β-cyclodextrin-Based Polymer

Candida rugosa lipase was encapsulated within a chemically inert sol–gel support prepared by polycondensation with tetraethoxysilane and octyltriethoxysilane in the presence of β-cyclodextrin-based polymer. The catalytic activity of the encapsulated lipases was evaluated both in the hydrolysis of p-nitrophenylpalmitate and the enantioselective hydrolysis of racemic Naproxen methyl ester. It has been observed that the percent activity yield of the encapsulated lipase was 65 U/g, which is 7.5 times higher than that of the covalently immobilized lipase. The β-cyclodextrin-based encapsulated lipases had higher conversion and enantioselectivity compared with covalently immobilized lipase. The study confirms an excellent enantioselectivity (E >300) for the encapsulated lipase with an enantiomeric excess value of 98% for S-naproxen.     

Phase composition and conductivity of La1 ? x Sr x ScO3 ? α (x = 0.01?0.20) under oxidative conditions

The phase composition was studied and overall conductivity of oxides La_{1 ? x} Sr _x ScO_{3 ? ??} (x = 0.01?0.20) was measured as dependent on air humidity (pH₂O = 0.04?2.35 kPa) in the temperature range from 100 to 900°C. The samples were synthesized in air at 1600°C. They are single-phase, with a perovskitetype structure with orthorhombic distortions and the density of 94?C99%. The conductivity measurements were carried out using the impedance technique and four-probe dc technique. The contributions of bulk and grain boundary resistances were determined, effective conductivity activation energies were calculated.     

New medicines and approaches to treatment of atherosclerosis

Prerequisites for the use of photodynamic therapy (PDT) to treatment of atherosclerosis, as well as the development and structure of atherosclerotic vascular lesions in humans are analyzed. The basic requirements for PDT components, specifically photosensitizers (PS), and the radiation source, and the current state of their development are overviewed. Some original results of in vitro studies of the effect of PS on the basis of phthalocyanines and radiation on cells from the atherosclerotic plaques are presented.     

Role of saturability of noncovalent interactions in the analysis of the three-dimensional structure—opioid activity relationship

The effect of the saturability of noncovalent interactions on the character of opioid activity of opioid receptor ligands belonging to different structural classes was investigated. A three-dimensional model for an opiate pharmacophore was used to show that the involvement of pharmacophore elements, which are responsible for the agonist ligand binding to opioid receptors, in intramolecular interactions gives rise to antagonistic properties.     

Neutron Diffraction Investigation of Langanite Crystals

The upper and lower parts of a single crystal with a nominal composition La₃Ga_5.5Nb_0.5O₁₄grown by the Czochralski method (Ir crucible, 99%Ar + 1%O₂, growth direction) have been studied by neutron diffraction for the first time. The compositions of the upper and lower parts are found to differ ((La_2.935(2)□_0.065)(Ga_0.450Nb_0.550(3))Ga₃(Ga_1.965(4) □_0.035)(O_13.90(1) □_0.10) and (La_2.940(1) □_0.060)(Ga_0.590Nb_0.410(2))Ga₅(O_13.82(1) □_0.18), respectively), and microtwin formation was observed in the upper part, with two unit cells related by the translation 1/2Z. Based on a comparison of the refined crystal composition and optical transmission spectra, the absorption bands at 30 000, 24 500, and 20 500 cm_-1 were assigned to divacancies (2 V _La^', 3 V _O^..), oxygen vacancies, and color centers, respectively. A relationship between the crystal color and oxygen content is established.     

X-ray diffraction study of p-(alkoxybenzylidene)-p′-toluidines: Crystal and molecular structure of C10H21O-C6H4-CH=N-C6H4-CH3

The crystal and molecular structure of p-(decaoxybenzylidene)-p′-toluidine C₁₀H₂₁O-C₆H₄-CH=N-C₆H₄-CH₃ is studied. The molecule is nearly planar. In the crystal packing, loose regions formed by aliphatic fragments of molecules alternate with pseudostacks of aromatic fragments of molecules that are related by the centers of symmetry. The stacks are built of dimers, in which molecules are linked by π-stacking interactions between benzene rings. There are no weak directional interactions between dimers in a stack. The presence of a single structure-forming element in the crystal, namely, the π-stacking interactions in the dimers, along with the similarity of the crystal packing to that of the C₈H₁₇O-homologue, which forms a nematic mesophase on melting, indicate that the crystals under study should exhibit nematic properties.     

Effect of change in structural and magnetic states of Pt<Subscript>74.1</Subscript>Fe<Subscript>25.9</Subscript> alloy on its optical properties

The effect of atomic disordering on the optical properties of Pt_74.1Fe_25.9 alloy, whose stoichiometry is close to that of Pt₃Fe, has been investigated. The optical constants of ordered and plastically deformed alloys, which are, respectively, in the paramagnetic and ferromagnetic states, have been measured by the polarimetric method. The frequency dispersions of the permittivity, optical conductivity, and reflectivity, as well as the microscopic characteristics of conduction electrons (plasma and relaxation frequencies), have been calculated. The energy dependences of the optical conductivity are compared to the calculated energy-band structure of atomically ordered and disordered Pt₃Fe compounds.     

Crystal and molecular structure of n-hexyloxyphenyl n-octyloxybenzoate

The X-ray crystal structure of n-hexyloxyphenyl n-octyloxybenzoate C₈H₁₇O-C₆H₄-COO-C₆H₄-OC₆H₁₃, which is a liquid-crystal compound, was determined. This compound forms smectic and nematic phases upon melting. A crystal-packing analysis revealed the following two types of structure-forming elements in the centrosymmetric pairs of molecules: a ??-stacking interaction and a C-H...??-system interaction. In the pairs of molecules linked by the latter type of interactions, there are two such interactions per pair, whereas one interaction occurs per pair of molecules linked by a ??-stacking interaction. Hence, the former pair of molecules is more stabilized through weak directional interactions than the latter pair.