Rapid Functional Definition of Extended Spectrum β-Lactamase Activity in Bacterial Cultures via Competitive Inhibition of Fluorescent Substrate Cleavage

The functional definition of extended-spectrum β-lactamase (ESBL) activity is a clinical challenge. Here we report a rapid and convenient assay of β-lactamase activity through the competitive inhibition of fluorescent substrate hydrolysis that provides a read-out nearly 40× more rapidly than conventional techniques for functional definition. A panel of β-lactam antibiotics was used for competition against β-lactamase enzyme-activated photosensitizer (β-LEAP) yielding a competitive index (C_i) in 30 min. Significant differences in the relative C_i values of the panel of β-lactams were determined in vitro for Bacillus cereus penicillinase. Additionally, the relative C_i values for whole bacterial cell suspensions of B. cereus 5/β were compared with the relative minimal inhibitory concentration (MIC) values and a correlation coefficient of 0.899 was determined. We further demonstrated the ability of β-LEAP to probe the capacity of ceftazidime to inhibit the enzyme activity of a panel of ESBL-producing Escherichia coli. The bacteria were assayed for susceptibility to ceftazidime and the relative MIC values were compared with the relative C_i values for ceftazidime yielding a correlation coefficient of 0.984. This work demonstrates for the first time the whole cell assay of the competitive inhibition of β-lactamase enzyme activity and derivation of associated constants.     

Synthesis,characterization and microwave‐assisted catalytic activity of novel benzimidazole salts bearing piperidine and morpholine moieties in Heck cross‐coupling reactions

A mixture of novel benzimidazole salts (2a–f), Pd(OAc)₂ and K₂CO₃ in DMF? H₂O catalyzes, in high yield, the Heck cross‐coupling reaction assisted by microwave irradiation in a short time. All synthesized novel benzimidazole derivatives were characterized by elemental analysis and NMR spectroscopy. In addition, the molecular structure of 2a was determined by X‐ray crystallography. Copyright © 2011 John Wiley & Sons, Ltd.     

Improvement of X-ray fluorescence sensitivity by dry ashing method for elemental analysis of bee honey

Elements, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Rb, and Sr in bee honey samples were determined using an improved dry ashing (DA) method for XRF with Mo-secondary target (Mo-XRF). The sensitivity of the DA method was significantly improved in comparison to the wet ashing (WA) and the direct (D) methods. The limits of detection (LODs) obtained by DA (3.4–0.007 µg/g) method were better by an order of magnitude than those obtained by WA (34.0–0.120 µg/g) and D (61.2–0.270 µg/g) methods. Further improvements in the sensitivity of the DA-XRF were achieved by using a Cu-secondary target for the excitation of the elements of K, Ca, Ti, Cr, and Mn. In this instance, the LODs were in the range of 0.220–0.024 µg/g. The results of DA-XRF analysis revealed a very good accuracy with errors less than 7.1% and a precision with a relative standard deviation (RSD) better than ± 8.8%.The improved DA-XRF analysis was applied for the determination of the above mentioned elements in several Syrian bee honey samples. The results were comparable to those obtained by the atomic spectrometry method with correlation coefficients better than 0.9927.     

Phase diagrams of competing quadruple and binary interactions on Cayley tree-like lattice: Triangular Chandelier

We study the phase diagrams for the Ising model on a Cayley tree-like lattice, called Triangular Chandelier, with competing nearest-neighbour interactions J₁, prolonged next-nearest-neighbour interactions J_p and one-level next-nearest-neighbour quadruple interactions J_l1. The phase diagrams display the multicritical points (the Lifshitz points) that are at nonzero temperature and many modulated phases. To perform this study, an iterative scheme similar to that appearing in real space renormalization group frameworks is established; it recovers, as particular case, previous work of Vannimenus extension result given by Ganikhodjaev and U?uz for k=3. At vanishing temperature, the phase diagram is fully determined for all values and signs of J₁,J_p and J_l1. At finite temperatures several interesting features are exhibited for typical values of J_l1/J₁ and −J_p/J₁.     

Extraction of aqueous of malic acid by trioctylamine extractant in various diluents

In this study malic acid were extracted from aqueous solution by different solvents with and without trioctylamine (TOA). The TOA was dissolved in five different esters (dimethyl phthalate, dimethyl adipate, dimethyl succinate, dimethyl glutarate, and diethyl carbonate), five different alcohols (isoamyl alcohol, hexan-1-ol, octan-1-ol, nonan-1-ol, and decan-1-ol) and two different ketones (diisobutyl ketone (DIBK) and methyl isobutyl ketone (MIBK)). The results are reported as distribution coefficients (K_D), loading factors (T_T), stoichiometric loading factor (T_S), separation factor (S_f) and extraction efficiency (E). The most effective solvent was determined as isoamyl alcohol with a distribution value coefficient of 17.811. The maximum values of equilibrium complexation constants in isoamyl alcohol for (acid:amine) (1:1) K₁₁ and (2:1) K₂₁ were 9.9 and 225.6, respectively. A linear solvation energy relationship (LSER) was accurately regressed to the experimental distribution coefficients.     

On binary signed digit representations of integers

Applications of signed digit representations of an integer include computer arithmetic, cryptography, and digital signal processing. An integer of length n bits can have several binary signed digit (BSD) representations and their number depends on its value and varies with its length. In this paper, we present an algorithm that calculates the exact number of BSDR of an integer of a certain length. We formulate the integer that has the maximum number of BSDR among all integers of the same length. We also present an algorithm to generate a random BSD representation for an integer starting from the most significant end and its modified version which generates all possible BSDR. We show how the number of BSD representations of k increases as we prepend 0s to its binary representation.     

Synthesis and spectral characterization of some new azo dyes and their metal complexes

A series of azo-metal chelate dyes have been synthesized by coupling substituted o-nitroaniline and p-t-/s-butylphenol. The spectral characterization of the azo dyes containing o-hydroxy group and azo-metal(II) chelate [metal(II): Cu, Ni, Co] dyes by IR spectra, UV–VIS spectra, NMR spectra, elemental analysis and magnetic susceptibility techniques are reported. The stoichiometry of the azo-metal chelates was determined by the spectroscopic titration method to be 1:2 (ML₂).     

Generalized abstract economy and systems of generalized vector quasi-equilibrium problems

The present paper is in two-fold. The first fold is devoted to the existence theory of equilibria for generalized abstract economy with a lower semicontinuous constraint correspondence and a fuzzy constraint correspondence defined on a noncompact/nonparacompact strategy set. In the second fold, we consider systems of generalized vector quasi-equilibrium problems for multivalued maps (for short, SGVQEPs) which contain systems of vector quasi-equilibrium problems, systems of generalized mixed vector quasi-variational inequalities and Debreu-type equilibrium problems for vector valued functions as special cases. By using the results of first fold, we establish some existence results for solutions of SGVQEPs.     

Spectrophotometric determination of novalgin in tablets by use of potassium iodate

An indirect colour reaction has been studied for determination of novalgin in tablets. The method is simple, rapid and reproducible with a relative standard deviation of 0.2%. Novalgin is determined spectrophotometrically by means of its colour reaction with potassium iodate. Beer's law is obeyed over the range 1-10 mg of drug. A tentative reaction mechanism has been proposed.