Biofuel cell anode based on the Gluconobacter oxydans bacteria cells and 2,6-dichlorophenolindophenol as an electron transport mediator

A basic scheme of the use of the Gluconobacter oxydans bacteria cells as a biocatalyst at an anode of a biofuel cell with air-based cathode is raised up. The anode and cathode of the cell are made of graphite; 2,6-dichlorophenolindophenol serves as an electron transport mediator; and glucose is the substrate to be oxidized. The open-circuit voltage is 55 mV, for the bacteria cell, the mediator, and glucose concentrations of 3 mg/ml (raw weight), 34 mM, and 10 mM, respectively. The voltage and current of the biofuel cell loaded with an external resistance of 10 kohm are 5.6 mV and 0.56 mA. The cell’s internal resistance is 88 kohm.     

On Diophantine approximations to log <Emphasis Type="Italic">x</Emphasis>

A lower bound for Diophantine approximations to linear combination of the numbers log(5/3) and (1/√15) arctan(1/√15) is obtained.     

Sorption capture of chlorine with carbon adsorbents from waste gases yielded by electrolysis of chloride solutions

The performance of various carbon materials in sorption capture of chlorine from waste gases yielded by electrolysis of nickel-manganese solutions was studied. A simple method was proposed for regeneration of carbons after sorption of chlorine, which makes them suitable for repeated use in sorption installations for chlorine capture.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 9, 2004, pp. 1462–1466.Original Russian Text Copyright © 2004 by Stavitskaya, Tomashevskaya, Goba, Kartel, Strelko.     

Synthesis of catalytic filamentous carbon on a nickel/graphite catalyst and a study of the resulting carbon-carbon composite materials in microbial fuel cells

The carbon-carbon composite materials obtained via the synthesis of catalytic filamentous carbon (CFC) on a Ni/graphite supported catalyst in the process of the pyrolysis of C₃–C₄ alkanes in the presence of hydrogen were systematically studied. The effects of the following conditions on the catalytic activity expressed as the yield of carbon (g CFC)/(g Ni) and on the character of CFC synthesis on graphite rods were studied: procedures for supporting Ni(II) compounds (impregnation and homogeneous precipitation), the concentrations of impregnating compouds (nickel nitrate, urea, and ethyl alcohol) in solution, graphite treatment (oxidation) conditions before supporting Ni(II) compounds, and the pyrolysis temperature of C₃–C₄ alkanes in the range of 400–600°C. Optimum conditions for preparing CFC/graphite composite materials, which are promising for use as electrodes in microbial fuel cells (MFCs), were chosen. The electrochemical characteristics of an MFC designed with the use of a CFC/graphite electrode (anode) and Gluconobacter oxydans glycerol-oxidizing bacteria were studied. The morphology of the surfaces of graphite, synthesized CFC, and also bacterial cells adhered to the anode was studied by scanning electron microscopy.     

New one-step procedure for the synthesis of 6H-chromeno[4,3-b]quinolines and 8a,9,14,14a-tetrahydro-8H-benzo[5,6]chromeno[4,3-b]quinolines

Schiff bases generated in situ from substituted anilines and 2-allyloxybenzaldehyde underwent acid-catalyzed intramolecular Diels-Alder reaction followed by dehydrogenation to give 6H-chromeno[4,3-b]-quinolines. Under analogous conditions, derivatives of 2-allyloxynaphthalene-1-carbaldehyde were converted into 8a,9,14,14a-tetrahydro-8H-benzo[5,6]chromeno[4,3-b]quinolines. Possible dehydrogenation mechanisms are discussed. Original Russian Text ? M.M. Tomashevskaya, O.A. Tomashenko, A.A. Tomashevskii, V.V. Sokolov, A.A. Potekhin, 2007, published in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 1, pp. 75–80.     

New Carbon Aerogels Fabricated from Polymeric Materials and Their Properties

Electron microscopy and adsorption-structural, X-ray phase, and thermal analyses were used to determine the density, porosity, microstructure, electrical conductivity, and reactivity of new carbon aerogels based on phenol-formaldehyde polymers.     

Development of Procedures for Synthesis of Carbon Materials with Molecular-Sieve Properties

New methods for synthesis of uniformly porous carbon materials with sieve properties and small apparent density from phenol-formaldehyde resins were developed; the optimal conditions of their synthesis were determined. New types of finely dispersed carbon powders were prepared using various treatment procedures at different stages; the structural and sorption properties of the resulting materials were studied.     

Diophantine approximations of the number π by numbers from the field ℚ(√3)

We prove an estimate of the irrationality measure of any nonzero number of the form r ₁ π + r ₂ π/√3, r ₁, r ₂ ? ?(√3)     

Factors Determining the Sorption Capacity and Selectivity of Metal-Substituted Carbon Sorbents for Ligand Sorption from the Gas Phase

We have established that it is feasible to significantly increase the capacity and selectivity of carbon sorbents by modifying them with metal ions during sorption from gas/air mixtures of sulfur dioxides and nitrogen, hydrogen sulfide, carbon disulfide, diethylamine, acetic acid, etc. We have determined the role of surface complexation and other factors affecting sorption; we have determined the routes and principles for creating and using new high-capacity and selective sorbents for these materials based on various carbonaceous materials (activated carbons, carbonaceous cloths, semicokes).     

On the Bose–Einstein Condensate of Excitons in Crystals with Defects

Optics and Spectroscopy - The possibility of formation of a Bose–Einstein condensate (BEC) of excitons in a model nonideal lattice of a molecular crystal is considered. The spectrum of...