Tear analysis of ascorbic acid,uric acid and malondialdehyde with capillary electrophoresis

Tears have a significant role in antioxidant defense in ocular tissues and since their collection is quick and noninvasive, their analysis would facilitate monitoring of pathophysiological changes. However, their low volume and low content of antioxidants makes analysis difficult; methods of high sensitivity are needed. In this paper, we present a method for tear analysis of two antioxidant molecules (ascorbic and uric acid) and of a lipid peroxidation indicator (malondialdehyde) with capillary electrophoresis. Tears were collected with Schirmer strips, extracted with a low‐pH phosphate buffer, centrifuged through membrane filters and an antioxidant was added. They were stable at ?70°C for 15 days. After pilot experiments, optimum electrophoretic separation was achieved in a 25 mm borate buffer, pH 10.0, containing 100 mm sodium dodecyl sulfate at 25°C and 20 kV. The developed method has good repeatability (<5% RSD), precision (<15% relative error values) and high sensitivity (LLOQ values of 20, 2.3 and 2.5 μM for ascorbate, urate and malondialdehyde, respectively). It was applied to the analysis of tears from healthy individuals and the antioxidant levels are in agreement with those obtained with other techniques. This method might serve as a tool to clarify the role of endogenous antioxidants in the pathophysiology of ocular diseases. Copyright © 2009 John Wiley & Sons, Ltd.     

An intelligent agent negotiation strategy in the electronic marketplace environment

E-commerce will strongly penetrate the market if coupled with appropriate technologies and mechanisms. Mobile agents may enhance the intelligence and improve the efficiency of systems in the e-marketplace. We propose a dynamic multi-lateral negotiation model and construct an efficient negotiation strategy based on a ranking mechanism that does not require a complicated rationale on behalf of the buyer agents. This strategy can be used to extend the functionality of autonomous intelligent agents, so that they quickly reach to an agreement aiming to maximise their owner’s utility. The framework proposed considers both contract and decision issues, is based on real market conditions, and has been empirically evaluated. Moreover, it is shown that in a linear framework like the one we employ, more elaborate ranking mechanisms do not necessarily improve efficiency.     

-bounds for spectral multipliers on graphs

We prove that certain spectral multipliers associated with the discrete Laplacian on graphs satisfying the doubling volume property and the Poincaré inequality are bounded on the Hardy space .

     

Chemical composition and antimicrobial activity of the essential oil of Algerian Phlomis bovei De Noé subsp. bovei

The chemical composition of essential oil obtained by steam distillation of dried aerial parts of Phlomis bovei De Noé subsp. bovei collected from Algeria, was analyzed by GC and GC/MS. Seventy five constituents (corresponding to 86.37% of the total weight) were identified. The main components were: germacrene D, beta-caryophyllene, beta-bournonene, thymol and hexahydrofarnesyl acetone. Furthermore, the antimicrobial activity of the oil was evaluated against six gram (+/-) bacteria and three pathogenic fungi, using the agar dilution technique. It was found that the oil exhibited strong antimicrobial activity against most of the tested microorganisms.     

Proteomics-based discovery of koranimine, a cyclic imine natural product

Nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs) are large enzymes responsible for the biosynthesis of medically and ecologically important secondary metabolites. In a previous report, we described a proteomics approach to screen for expressed NRPSs or PKSs from bacteria with or without sequenced genomes. Here we used this proteome mining approach to discover a novel natural product arising from rare adenylation (A) and reductase (Red) domains in its biosynthetic machinery. We also cloned the entire gene cluster and elucidated the biosynthesis of the new compound, which is produced by an unsequenced Bacillus sp. isolated from soil collected in Koran, Louisiana.     

Density functional study of structural, electronic, and optical properties of small bimetallic ruthenium-copper clusters

The structural, electronic, bonding, magnetic, and optical properties of bimetallic [Cu(n)Ru(m)](+/0/-) (n + m ≤ 3; n, m = 0-3) clusters were computed in the framework of the density functional theory (DFT) and time-dependent DFT (TD-DFT) using the full-range PBE0 nonlocal hybrid GGA functional combined with the Def2-QZVPP basis sets. Several low-lying states have been investigated and the stability of the ground state spinomers was estimated with respect to all possible fragmentation schemes. Molecular orbital and population analysis schemes along with computed electronic parameters illustrated the details of the bonding mechanisms in the [Cu(n Ru(m)](+/0/-) clusters. The TD-DFT computed UV-visible absorption spectra of the bimetallic clusters have been fully analyzed and assignments of all principal electronic transitions were made and interpreted in terms of contribution from specific molecular orbital excitations.     

All uncountable cardinals in the Gitik model are almost Ramsey and carry Rowbottom filters

Using the analysis developed in our earlier paper 5 , we show that every uncountable cardinal in Gitik's model of 8 in which all uncountable cardinals are singular is almost Ramsey and is also a Rowbottom cardinal carrying a Rowbottom filter. We assume that the model of 8 is constructed from a proper class of strongly compact cardinals, each of which is a limit of measurable cardinals. Our work consequently reduces the best previously known upper bound in consistency strength for the theory + “All uncountable cardinals are singular” + “Every uncountable cardinal is both almost Ramsey and a Rowbottom cardinal carrying a Rowbottom filter”.     

Unveiling connectivity patterns of categories in complex systems: An application to human needs in urban places

We present a methodology based on weighted networks and dependence coefficients aimed at revealing connectivity patterns between categories. As a case study, it is applied to an urban place and at two spatial levels—neighborhood and square—where categories correspond to human needs. Our results show that diverse spatial levels present different and nontrivial patterns of need emergence. A numerical model indicates that these patterns depend on the probability distribution of weights. We suggest that this way of analyzing the connectivity of categories (human needs in our case study) in social and ecological systems can be used to define new strategies to cope with complex processes, such as those related to transition management and governance, urban-making, and integrated planning.     

Study of the interactions of sodium thiocyanate, potassium thiocyanate and ammonium thiocyanate in water+N,N-dimethylformamide mixtures by Raman spectroscopy

Raman spectra of water+N,N-dimethylformamide (DMF) mixtures and their solutions with NaNCS, KNCS and NH(4)NCS were obtained. The bands of nu(CO) stretching, delta(OCN) bending, r(CH(3)) rocking and nu(N-CH)(3)) stretching of the DMF molecule with and without salts were studied. The dependence of the vibration frequencies and Raman intensities of the bands on the composition of the mixed solvent was discussed. The change of the band frequencies as a result of the presence of the salts and the solvation of the cations by the solvent molecules was examined. The stronger cation solvation by the aprotic solvent molecules instead of the water molecules in DMF concentrated solutions was discussed. The nu(CN) and nu(CS) vibrations of the SCN(-) ions were observed as a function of the cation present and the solvent composition. The presence of the SCN(-) ions as "free", contact ion pairs, or solvent separated pairs, was discussed.