Electrochemical studies of methyl substituted 1,4-quinones: Part I. The electrochemical dimerization of duroquinone

The electrochemical reduction of duroquinone produces diduroquinone in high yields. The dimerization is proposed to proceed via a catalytic process as the current passed is much less than one electron per molecule. Diduroquinone can be electrochemically cleaved to duroquinone anion radical by reduction. Several possible mechanisms are presented to explain the catalytic dimerization of duroquinone.     

Enzyme-catalyzed cascade synthesis of hydroxyiminoacetamides

In order to synthesize N-(3-azido-1-phenylpropyl)-2-hydroxyiminoacetamide, a key compound for the preparation of acetylcholinesterase (AChE) reactivators of the N-substituted 2-hydroxyiminoacetamide type, it was necessary to develop a method for forming an amide bond between an ethyl glyoxylate oxime and an amine. Using Candida antarctica lipase B (CAL-B) in a cascade enzyme-BOP catalyzed reaction, the efficient synthesis of the target hydroxyiminoacetamide was achieved.     

A new method for strategic decision-making in higher education

Central European Journal of Operations Research - Using the appropriate methodology for strategic decision-making in higher education is crucial to make effective decisions. In this paper, the...     

Analysis and numerical simulation of magnetic forces between rigid polygonal bodies. Part II: Numerical simulation

The analysis of magnetoelastic phenomena is a field of active research. Formulae for the magnetic force in macroscopic systems have been under discussion for some time. In Popović et al. (Continum. Mech. Thermodyn. 2007), we rigorously justify several of the available formulae in the context of rigid bodies in two and three space dimensions. In the present, second part of our study, we investigate these formulae in a series of numerical experiments in which the magnetic force is computed in dependence on the geometries of the bodies as well as on the distance between them. In case the two bodies are in contact, i.e., in the limit as their distance tends to zero, we focus especially on a formula obtained in a discrete-to-continuum approximation. The aim of our study is to help clarify the question which force formula is the correct one in the sense that it describes nature most accurately and to suggest adequate real-life experiments for a comparison with the provided numerical data.      

Rigorous Asymptotic Expansions for Critical Wave Speeds in a Family of Scalar Reaction-Diffusion Equations

We investigate traveling wave solutions in a family of reaction-diffusion equations which includes the Fisher–Kolmogorov–Petrowskii–Piscounov (FKPP) equation with quadratic nonlinearity and a bistable equation with degenerate cubic nonlinearity. It is known that, for each equation in this family, there is a critical wave speed which separates waves of exponential decay from those of algebraic decay at one of the end states. We derive rigorous asymptotic expansions for these critical speeds by perturbing off the classical FKPP and bistable cases. Our approach uses geometric singular perturbation theory and the blow-up technique, as well as a variant of the Melnikov method, and confirms the results previously obtained through asymptotic analysis in [J.H. Merkin and D.J. Needham, (1993). J. Appl. Math. Phys. (ZAMP) A, vol. 44, No. 4, 707–721] and [T.P. Witelski, K. Ono, and T.J. Kaper, (2001). Appl. Math. Lett., vol. 14, No. 1, 65–73].     

Cluster‐based molecular docking study for in silico identification of novel 6‐fluoroquinolones as potential inhibitors against Mycobacterium tuberculosis

A classical protein sequence alignment and homology modeling strategy were used for building three Mycobacterium tuberculosis‐DNA gyrase protein models using the available topoII‐DNA‐6FQ crystal structure complexes originating from different organisms. The recently determined M. tuberculosis‐DNA gyrase apoprotein structures and topoII‐DNA‐6FQ complexes were used for defining the 6‐fluoroquinolones (6‐FQs) binding pockets. The quality of the generated models was initially validated by docking of the cocrystallized ligands into their binding site, and subsequently by quantitative evaluation of their discriminatory performances (identification of active/inactive 6‐FQs) for a set of 145 6‐FQs with known biological activity values. The M. tuberculosis‐DNA gyrase model with the highest estimated discriminatory power was selected and used afterwards in an additional molecular docking experiment on a mixed combinatorial set of 427 drug‐like 6‐FQ analogs for which the biological activity values were predicted using a prebuilt counter‐propagation artificial neural network model. A novel three‐level Boolean‐based [T/F (true/false)] clustering algorithm was used to assess the generated binding poses: Level 1 (geometry properties assessment), Level 2 (score‐based clustering and selection of the (T)‐signed highly scored Level 1 poses), and Level 3 (activity‐based clustering and selection of the most “active” (T)‐signed Level 2 hits). The frequency analysis of occurrence of the fragments attached at R₁ and R₇ position of the (T)‐signed 6‐FQs selected in Level 3 revealed several novel attractive fragments and confirmed some previous findings. We believe that this methodology could be successfully used in establishing novel possible structure‐activity relationship recommendations in the 6‐FQs optimization, which could be of great importance in the current antimycobacterial hit‐to‐lead processes. © 2012 Wiley Periodicals, Inc.