Microbial conversion of synthesis gas components to useful fuels and chemicals

Applied Biochemistry and Biotechnology - Enriched culture techniques have been used to isolate microbial cultures exhibiting growth on synthesis gas components. Three rod-shaped, gram-positive...     

Structural classification of layered dichalcogenides of group IV B,V B and VI B transition metals

A classification of the trigonal prismatic and octahedral structures exhibited by the layered dichalcogenides of group IV B, V B and VI B metals is achieved through consideration of the relative size, polarisation of the bonding orbitals, and the ionicity of the metal-chalcogen bond. A plot of the ratio of the covalent radii of the metal and chalcogen atoms against Pauling's resonating bond ionicity is shown to successfully achieve a separation of the two structures, consistent with the primarily covalent nature of the bonds.     

Relative intensities in x-ray photoelectron spectra. Part II

Experimental data on the relative intensities of X-ray photoelectron lines of some elements with 22 ? Z ? 56, and the calculations for the photoionization cross-sections for inner levels of some elements with 21 ? Z ? 63 are reported. The relationship between photoionization relative cross-sections and line relative intensities is examined. Theoretical values of the photoionization cross-sections were used in the calculations of relative intensities of molecular valence levels for AO₄^x? (A = Cl, S, P, Se, As), AF₆^x? (A = S, Si, Al), COS, CS₂ and H₂S.     

Mutually exclusive and exhaustive quantum states

The identification of a set of mutually exclusive and exhaustive propositions concerning the states of quantum systems is a corner stone of the information-theoretic foundations of quantum statistics; but the set which is conventionally adopted is in fact incomplete, and is customarily deduced from numerous misconceptions of basic quantum mechanical principles. This paper exposes and corrects these common misstatements. It then identifies a new set of quantum state propositions which is truly exhaustive and mutually exclusive, and which is compatible with the foundations of quantum theory.Work supported by a grant from Research Corporation.     

A new method for calculating non-ideal point defect induced electronic structure: Application to GaAs1−xPx:O1

We report a new method for calculating non-ideal defect induced electronic structure in crystalline semiconductors. The method is based upon solving the Dyson equation using the transfer matrix technique. The method allows us to include realistic distortions around defects (impurities, vacancies, etc.) in solving for the electronic structure. Results are presented for the system GaAs_1?xP_x:O in which oxygen replaces the anion. Several different distortions are considered and the results are found to agree remarkably well with experiments.     

Resolving the isospectrality of the dihedral graphs by counting nodal domains

We discuss isospectral quantum graphs which are not isometric. These graphs are the analogues of the isospectral domains in R² which were introduced recently in [1–5] all based on Sunada's construction of isospectral domains [6]. After discussing some of the properties of these graphs, we present an example which support the conjecture that by counting the nodal domains of the corresponding eigenfunctions one can resolve the isospectral ambiguity.     

Fast chromatographic method for the determination of dyes in beverages by using high performance liquid chromatography—Diode array detection data and second order algorithms

A fast chromatographic methodology is presented for the analysis of three synthetic dyes in non-alcoholic beverages: amaranth (E123), sunset yellow FCF (E110) and tartrazine (E102). Seven soft drinks (purchased from a local supermarket) were homogenized, filtered and injected into the chromatographic system. Second order data were obtained by a rapid LC separation and DAD detection. A comparative study of the performance of two second order algorithms (MCR-ALS and U-PLS/RBL) applied to model the data, is presented. Interestingly, the data present time shift between different chromatograms and cannot be conveniently corrected to determine the above-mentioned dyes in beverage samples. This fact originates the lack of trilinearity that cannot be conveniently pre-processed and can hardly be modelled by using U-PLS/RBL algorithm. On the contrary, MCR-ALS has shown to be an excellent tool for modelling this kind of data allowing to reach acceptable figures of merit. Recovery values ranged between 97% and 105% when analyzing artificial and real samples were indicative of the good performance of the method. In contrast with the complete separation, which consumes 10 mL of methanol and 3 mL of 0.08 mol L⁻¹ ammonium acetate, the proposed fast chromatography method requires only 0.46 mL of methanol and 1.54 mL of 0.08 mol L⁻¹ ammonium acetate. Consequently, analysis time could be reduced up to 14.2% of the necessary time to perform the complete separation allowing saving both solvents and time, which are related to a reduction of both the costs per analysis and environmental impact.     

A sensitive spectrophotometric method for lead determination by flow injection analysis with on-line preconcentration

A new flow injection (FI) system for the determination of Pb(II) at trace level with a preconcentration step and spectrophotometric detection is proposed. It is based on preconcentration of lead ions on chitosan and dithizone-lead complex formation in aqueous medium (pH 9). The chemicals and FIA variables influencing the performance of the system were optimized and applied to the determination of lead in natural, well, and drinking water samples. It is a simple, highly sensitive, and low cost alternative methodology. The method provided a linear rage between 25 and 250 μg l⁻¹, a detection limit of 5.0 ng ml⁻¹ and a sample throughput of 15 h⁻¹. The obtained results of spiked samples are in good agreement between the proposed method and ICP-AES.     

Novel one-pot synthesis of 4H-chromene derivatives using amino functionalized silica gel catalyst

A simple, efficient, and environmentally benign method for the synthesis of 4H-chromene derivatives was developed using well ordered and recoverable amino functionalized silica gel as a base catalyst. The 4H-chromene derivatives were obtained in short time and excellent yield(87%–96%) by three component reaction of aldehydes, malononitrile and cyclic 1,3-diketones in water at 70 8C.     

Simultaneous Determination of Pioglitazone,Metformin, and Glimepiride in Pharmaceutical Preparations using HPTLC Method

JPC – Journal of Planar Chromatography – Modern TLC - A simple, precise, and accurate high-performance thin-layer chromatography (HPTLC) method for the simultaneous determination of...