Textural analysis of extruded materials with rhombohedral structure

A textural analysis of extruded rods of material with tetradymite (Bi₂Te₃) structure is conducted by constructing the distribution of the pole density of the (0001) and (1120) planes. The distribution of the poles of the planes is represented by a solid of revolution, and the pole density, which is a function of the angle () of the deviation of the normals to h_i from the extrusion axis, is determined by the diffraction method of specimen inclination using the diffracted ray intensity. It proves possible to identify textural components, and to determine how many there are and the degree of perfection of this method. A technique is worked out for the quantitative estimate of the average values of the components of the conductivity tensor in the grains, and the contribution of the texture to the macroscopic properties of the material is analyzed. To investigate the thin layers (for example, the layerwise distribution of texture in rods of rectangular cross section) we used the method of inverse pole diagrams, where the probability of coincidence of the h_i plane with the working surface of the specimen is analyzed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 33–39, December, 1989.     

The effect of side substituents on rotation hindrance in polyheteroarylenes

Hindered rotation was considered in calculations of the conformational parameters of a series of polyheteroarylenes with bulky side substituents by the Monte-Carlo method. Within the range of experimental errors, the results of calculations for several polyarylates coincide with the values of conformational rigidity, determined from hydrodynamic experimental data. The proposed procedure was used to estimate the rigidities of a number of polymers with bulky side substuents for which experimental determination is difficult. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1287–1296, July, 1998.     

Synthesis of amorphous block copoly(arylene ether ketones) and their characterization

Exchange reactions that may proceed in the course of polycondensation during formation of a polymer from 4,4′-difluorobenzophenone and 4,4′-(isopropylidene)diphenol have been studied. It has been shown that the molecular mass of the polymer decreases under the action of 4,4′-(isopropylidene)diphenol diphenolate. The nucleophilic substitution of the activated aryl halide in DMAA in the presence of potassium carbonate yields high-molecular-mass block copoly(arylene ether ketones) based on 4,4′-difluorobenzophenone and a number of bisphenols. It was demonstrated the synthetic procedure and the chemical structure of block copoly(arylene ether ketones) strongly affect the onset temperature of softening and the mechanical characteristics of the films based on these polymers.     

Synthesis of substitued 4,4-diacetylaminopiperidines

The synthesis of a series of 4,4-diacetylaminopiperidines has been achieved by the reaction of 4-piperidones, described earlier, with acetonitrile in the presence of concentrated sulfuric acid. The structure and the three-dimensional constitution of the compounds has been confirmed by IR, PMR, and mass spectrometric data.     

Transformation optics and infrared metamaterials for optical devices

The coordinate transformation approach is applied for the design of an optical mode adaptor between two different width waveguides in the near IR telecom optical domain. The control of the mode profile in the adaptor is achieved by considering a composite waveguide consisting of a thin metamaterial (MM) layer intercalated between 2???m thick SU8 photoresist slab and a glass substrate. We demonstrate that intercalated metafilm enables the realization of a space coordinate transformation and allows a precise control of the light propagation in the composite waveguide. Numerical simulations and experimental realizations of the metamaterial layer are performed in order to validate the device concept and realization feasibility.     

Immunomodulatory properties of silver-containing nanocomposite on the basis of polyvinyltriazole

Russian Chemical Bulletin - The water-soluble nanocomposite with the uniform distribution of silver nanoparticles in polymer matrix was synthesized on the basis of poly-1-vinyl-1,2,4-triazole....     

Stereoselective preparation of mono- and bis-derivatives of pentacyclo[6.3.0.02,6.03,10.05,9] undecane (D 3-trishomocubane)

The rearrangement of easily accessible Cookson’s diketone with chlorosulfonic acid in chloroform followed by the acidic hydrolysis gave 6-chloro-7-hydroxy-dichloropentacyclo[6.3.0.0^2,6.0^3,10.0^5,9]undecane-4-one, whose syn-stereochemistry was assigned through the X-ray crystal structure analysis. This key structure was used for the stereoselective synthesis of the D ₃-trishomocubane derivatives as well as for the preparation of potential drugs bearing hydroxy- and amino-functional groups. A new multigram preparative synthesis of D ₃-trishomocubane was developed.      

Electrochemically deposited thiophene-based polymers as protective agents for Prussian Blue thin films

A composite material based on overlapped layers of electrochemically synthesized Prussian Blue (PB) and terthiophene-derived polymer is described, aiming at enhancing the stability of the hexacyanoferrate thanks to the protective action of the polymer. Two bilayer configurations and deposition methods (for the polymer component) were tested. The morphology and electrochemical behavior in organic solvent and in aqueous solutions containing different supporting electrolytes were carried out. The best performances of electrodes modified with films of the composite material as to increased stability of PB were achieved with the potentiostatically deposited polymer covering the PB layer, in acetate buffer at pH 5.5. As for potential cycling stress, the anodic and cathodic peak currents due to PB were not decreased after 20 cycles. Conversely, PB alone displayed the anodic peak currents relevant to PB/Prussian White (PW) and PB/Berlin Green (BG) systems decreased by about 30 %. The stability to local pH increase was assessed by cyclic voltammetry after electrochemical reduction of H₂O₂. For example, the anodic peak currents were decreasing by 15 % and 5 % for the two PB redox systems, while for PB alone the same currents decreased by 35 % and 10 %. The response sensitivity to hydrogen peroxide was improved by 54 %, with respect to PB alone, as evaluated by chronoamperometry.     

Propane‐1,2‐diols from Dilactides,Oligolactides, or Poly‐L‐lactic Acid (PLLA): From Plastic Waste to Chiral Bulk Chemicals

The preparation of racemic or enantioenriched propane‐1,2‐diol from dilactides, oligolactides, or poly‐L ‐lactic acid (PLLA) is described. The transformation is carried out as tandem reactions in MeOH, covering hydrolysis and subsequent hydrogenation by using copper chromite as a catalyst. The starting material present undesired side products of the PLLA synthesis or PLLA waste.