Use of Voltammetry for Determining Antibiotics Streptomycin and Azitromycin

Conditions were selected for the voltammetric determination of streptomycin and azitromycin using electrodes of different types. The interfering effects of cations, anions, and organic substances, food proteins among them, on the analytical signals from antibiotics were estimated. Procedures for determining streptomycin and azitromycin in pharmaceuticals and for determining streptomycin in milk at nano levels were developed.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 6, 2005, pp. 586–591.Original Russian Text Copyright © 2005 by Fedorchuk, Puchkovskaya, Anisimova, Slepchenko.Presented at the VI All-Russian Conference (with international participation) on Electrochemical Methods of Analysis (EMA-2004, Ufa, May 23–27, 2004).     

Lateral interactions and multi-isotherms: nitrogen recombination from Rh(111)

Lateral adsorbate-adsorbate interactions result in variation of the desorption rate constants with coverage. This effect can be studied in great detail from the shape of a multi-isotherm. To produce the multi-isotherm, the temperature is increased in a (semi)stepwise fashion to some temperature, followed by maintaining this temperature for a prolonged time. Then, the temperature is stepped to a higher value and held constant at this new temperature. This cycle is continued until all of the adsorbates have desorbed. Using a detailed kinetic Monte Carlo model and an optimization algorithm based on Evolutionary Strategy, we are able to reproduce the shape of the experimentally measured multi-isotherm of nitrogen on Rh(111) and obtain the lateral interactions between the nitrogen atoms.     

A family of multiderivative methods for the numerical solution of the Schrödinger equation

A family of multiderivative methods with minimal phase-lag are introduced in this paper, for the numerical solution of the Schrödinger equation. The methods are called multiderivative since uses derivatives of order two, four or six. Numerical application of the new obtained methods to the Schrödinger equation shows their efficiency compared with other similar well known methods of the literature.Active Member of the European Academy of Sciences and Arts     

Determination of Aroma Compounds in Blackberry by GC/MS Analysis

The aromatic composition of five blackberry cultivars (Bursa 2, Navaho, Nessy, Chester Thornless, and Jumbo) was studied. The Im-SPME (Immersion Solid Phase Micro Extraction) extraction technique was applied and the samples were analyzed by GC/MS. Furfural and its derivatives were found to be the major aromatic compounds and 5-hydroxymethylfurfural was the most abundant compound in all the blackberry varieties.     

Continuous flow thin layer headspace (TLHS) analysis

Summary The paper presents a new method of a continuous isolation and determination of volatile organic halogens (VOX) in drinking waters based on so-called thin layer headspace (TLHS) isolation technique. The liberated volatile compounds are mineralized in an empty quartz tube at 850°C and absorbed in a buffered washing solution. After separation of air the halogen ions are determined potentiometrically in a flow-through cell using a silver/silver choride indicating electrode. The potential of the electrode is a linear function of the halogen ion concentration in the washing solution within the VOX concentration range usually encountered in drinking waters. The estimated detection limit of the method is ca. 0.1 g/l VOX and can be further improved by increasing the concentration factor. The theory of the TLHS isolation method has been further developed and verified. The derived dependences enable a simultaneous determination of the effective partition coefficients in the system, thus enabling calculation of the optimal gas flow rate.Part I and II, see [1, 2]     

The DTA analysis of amorphous Co-Fe-Si-B alloys

The compositional dependence of the DTA curves was analyzed for Fe_xCo78–_xSi₉B₁₃ metallic glasses. The crystallization temperature were determined. The results suggest that the thermal stability rises with increasing iron content.

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Zusammenfassung An metallischen GlÄsern FexCo78–xSi9B13 wurde die AbhÄngigkeit der DTA-Kurven von der Zusammenfassung untersucht. Den Ergebnissen nach steigt die thermische StabilitÄt mit wachsendem Eisengehalt.

     

Nanobiotechnology and its role in the development of new analytical devices

Physical methods of molecule observation and manipulation will prove useful, not only as research tools for investigating biomolecular structure and behavior, but also for the creation of nanostructures. Supramolecular and self-assembling structures are able to generate nanostructures, with many such systems being of biological origin. They form the interface between nanotechnology and biotechnology. Whereas biotechnological processes usually involve populations of cells or molecules, nanotechnological methods operate at the level of individual molecule manipulation. This article considers what advances have been made through cross-fertilisation between nanotechnology and biotechnology to develop for the next millennium new analytical tools at the microscale, using nanostructures as the sensitive part and with the ability to detect individual molecules.     

Development of a computer-based system for fast neutron cyclic activation analysis

We have developed a computer-controlled system for carrying out cyclic neutron activation analysis using fast neutrons. The system is basically a mechanical, pneumatic transfer system in which the sample is cycled between an irradiation position and a Ge detector. The sequence of movements between these two position is under computer control as is the timing of the various parts of the cycle. In addition, flux monitoring and correction are carried out using a computer-controlled scaler and the -ray counting is similarly controlled. The key to this control is the use of an interface containing a DCP BUS which receives signals from various valves for control of sample movement or to the scaler or ADC to initiate counting storage or calculations of the data. Finally, some preliminary data obtained with this technique are presented for the inelastic scattering reactions on barium.     

Enzymatic oxidation of lignin and compounds modeling it. V. Products of peroxidase oxidation of α-guaiacylpropanone

Using -guaiacylpropanone as an example, it has been shown that, in the process of peroxidase oxidation of carbonyl-containing structures, biphenyl compounds having C-C bonds in the 5-5 positions are formed. On the basis of the results of physicochemical methods of analysis, the formation of biphenyl spatially hindered structures with screened radical centers is suggested.Siberian Scientific-Research Institute of Cellulose and Cardboard, Bratsk. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 111–115, January–February, 1988.     

Geometric structure and electronic properties of neutral and anionic Fe2C3 and Fe2C4 clusters, as obtained by density-functional calculations

We calculated the geometrical structures and electronic properties of neutral and anionic Fe2Cn clusters (n = 3,4) using a density-functional method that employs linear combinations of atomic orbitals as basis sets, standard nonlocal norm-conserving pseudopotentials, and the generalized gradient approximation to exchange and correlation. We show that the ground-state structures of Fe2C3 and Fe2C4 are essentially the same in the neutral and anionic states, namely, planar rings that feature nonadjacent Fe atoms. For the anionic clusters, these findings contrast with previously published results.