Function Spaces and Contractive Extensions in Approach Theory: The Role of Regularity

Two classical results characterizing regularity of a convergence space in terms of continuous extensions of maps on one hand, and in terms of continuity of limits for the continuous convergence on the other, are extended to convergence-approach spaces. Characterizations are obtained for two alternative extensions of regularity to convergence-approach spaces: regularity and strong regularity. The results improve upon what is known even in the convergence case. On the way, a new notion of strictness for convergence-approach spaces is introduced.     

Modulation of volume fraction results in different kinetic effects in Belousov-Zhabotinsky reaction confined in AOT-reverse microemulsion

The effects of volume fraction modulations on a Belousov-Zhabotinsky reaction catalyzed by the photosensitive Ru(bpy)(3)(+2) confined in an AOT microemulsion system are analyzed. Kinetic observables such as the induction time or the initial oscillation period demonstrate two different types of correlation with the volume fraction depending on whether the system is below or above the microemulsion percolation threshold. Temporal evolution also demonstrates an exponential growth of the period with the number of oscillations independent of the volume fraction of the system.     

Protein folding in a reverse micelle environment: the role of confinement and dehydration

Characterization of the molecular interactions that stabilize the folded state of proteins including hydrogen bond formation, solvation, molecular crowding, and interaction with membrane environments is a fundamental goal of theoretical biophysics. Inspired by recent experimental studies by Gai and co-workers, we have used molecular dynamics simulations to explore the structure and dynamics of the alanine-rich AKA(2) peptide in bulk solution and in a reverse micelle environment. The simulated structure of the reverse micelle shows substantial deviations from a spherical geometry. The AKA(2) peptide is observed to (1) remain in a helical conformation within a spherically constrained reverse micelle and (2) partially unfold when simulated in an unconstrained reverse micelle environment, in agreement with experiment. While aqueous solvation is found to stabilize the N- and C-termini random coil portions of the peptide, the helical core region is stabilized by significant interaction between the nonpolar surface of the helix and the aliphatic chains of the AOT surfactant. The results suggest an important role for nonpolar peptide-surfactant and peptide-lipid interactions in stabilizing helical geometries of peptides in reverse micelle environments.     

Summary of ISO/TC 201 Technical Report: ISO/TR 19319:2013 – Surface chemical analysis – Fundamental approaches to determination of lateral resolution and sharpness in beam‐based methods

This Technical Report revises ISO/TR 19319:2003 —Surface chemical analysis—Auger electron spectroscopy and X‐ray photoelectron spectroscopy—Determination of lateral resolution, analysis area and sample area viewed by the analyser. The revised Technical Report gives a short introduction to basic models of image formation and introduces functions which characterize the performance of imaging instruments with respect to lateral resolution and sharpness. The determination of lateral resolution by imaging of square‐wave gratings and the determination of sharpness by imaging of narrow stripes and straight edges are described in detail. Finally, physical factors affecting lateral resolution, analysis area and sample area viewed by the analyser are discussed. Copyright © 2013 John Wiley & Sons, Ltd.     

Self-assembled monolayers for liquid crystal alignment: simple preparation on glass using alkyltrialkoxysilanes

A simple procedure for the preparation of octadecylsiloxane self-assembled monolayers (SAMs) on float glass substrates is described. The method utilizes commercial octadecyltriethoxysilane, OTE: n-C₁₈H₃₇Si(OCH₂CH₃)₃, as the SAM precursor, with deposition accomplished in toluene solution using n-butylamine as catalyst. This synthetic approach obviates the use of the problematic trichlorosilanes typically required for the preparation of high quality SAMs, and is characterized by a wide ‘process window,’ utilizing off-the-shelf reagents without special handling.     

Analysis of long-chain fatty acids in grey wastewater with in-vial derivatisation

The presence and levels of long-chain fatty acids (C₆–C₂₀) in grey wastewater from bathrooms have been investigated. The acids were purified and concentrated by solid-phase extraction on strong anion exchange discs, in-vial derivatised to their corresponding methyl ester and subsequently analysed by GC-MS. The method was able to quantify the acids at concentration <1?µg/L with a recovery of 31–97%. The levels of fatty acids were found in the range of <0.5 to 27?100?µg/L and the highest levels were found for the saturated lauric (C₁₂), palmitic (C₁₆) and stearic (C₁₈) acids. The treatment efficiency of a local treatment plant was evaluated by comparing concentrations of fatty acids at the inlet and the outlet. It was found that the treatability decreases with increasing chain length for the saturated acids (19–100% degradation) whereas the corresponding mono unsaturated acids were more easily degraded.     

Survey of low-level endocrine disrupting pesticides in food matrices in Slovakia

The search on endocrine disrupting chemicals (EDCs) in non-fatty food was evaluated. A fast, high-throughput, accurate, multiresidue method for the analysis of selected EDC pesticides in fruit and vegetable food samples was developed. The QuEChERS technique was used for sample preparation. Fast GC-MS was performed with a narrow-bore capillary column and a quadrupole benchtop detector with electron ionization (EI) and negative chemical ionization (NCI). A part of the work was devoted to the comparison of NCI versus EI approach concerning the sensitivity of detection and to the study of selectivity enhancement in NCI mode. Matrix-matched standard solutions were utilized for calibration. The methods validation was performed. Fortification studies at 1, 5, 10 and 250?µg?kg^?1 for 35 pesticides in EI mode and 0.1, 1, 5 and 250?µg?kg^?1 for 28 pesticides in NCI mode were performed. Average recoveries for each fortification level ranged from 70 to 110% with >80% of recoveries between 90 and 110%. Limits of quantification (LOQs) were established at 5?µg?kg^?1 for EI and at 1?µg?kg^?1 for NCI mode, which is lower than the lowest maximum residue level (MRL) value set by the European Commission in fruit and vegetables. The developed and validated fast GC-MS method was successfully applied to the search of EDC pesticides at ultratrace concentration level in real fruit and vegetable samples in Slovakia. Thirty-four samples of 20 different commodities were analyzed. Seven samples contained residues of three or more EDCs pesticides.     

Novel quercetin derivatives: synthesis and screening for anti-oxidant activity and aldose reductase inhibition

The direct acylation of quercetin (I) with 3-chloro-2,2-dimethylpropanoyl chloride (II) gives a complex reaction mixture. The synthesis of different acylated quercetin with from mono- to tetra-O-substituted functions was achieved in a simple procedure wherein the yield of isomers depended on the stoichiometric ratio of reagents. The crude reaction mixtures were analysed (LC-MS) and compared with the isolated products. Unambiguous structural characterisation of isomeric quercetin derivatives was confirmed by NMR analysis. In addition, the quercetin dimer can be obtained in a high yield in the simple procedure. The anti-oxidant activity and aldose reductase inhibition of the compounds were screened with the aim of providing bi-functional remedies to treat diabetic complications and other diseases where oxidative stress and the polyol pathway are key etiological factors.     

Interaction of oligonucleotides with benzo[c]phenanthridine alkaloid sanguilutine

Benzo[c]phenanthridine alkaloid sanguilutine was extracted and purified from the dried roots of Sanguinaria canadensis. The interaction of the positively charged iminium form of alkaloid with double-stranded DNA oligonucleotides was studied using luminescence spectroscopy. The results showed that the interaction with various double-stranded oligonucleotides was not specific to A-T or G-C base pairs; also, no preference was found for either homogeneous or heterogeneous base composition of strands. The association constants were calculated to be in the range of (1.31–14.36) × 10⁵ M^?1. The luminescence intensity response at 610 nm to low concentrations of double-stranded DNA was found to be linear and can potentially be used for the fluorometric quantification of DNA. The limit of detection was estimated to be 120 ng mL^?1 of DNA (calculated by 3σ method).     

Sugar Analogues with Basic Nitrogen in The Ring as Anti-Infectives

1. INTRODUCTION

Infectious diseases have remained a serious problem for society and concerned government organisations. Due to the dramatic increase of international transport of goods and passengers, dangerous microbial species and infectious diseases can be rapidly distributed over large distances. According to estimations by the World Health Organisation (WHO), nearly 50,000 people are killed by infectious diseases daily. After having been kept at bay for decades, tuberculosis has returned to claim over three million lives per year. In addition, approximately thirty new infectious diseases such as Legionnaire's disease, HIV, or borreliosis have emerged during the past two decades.¹ Furthermore, long-known species, for example mycobacteria, the causative agents of such diseases as tuberculosis and leprosy, have acquired a high level of resistance to most commonly employed anti-infective agents. Because of the abundance of pathogenic microorganisms, a tremendous fraction of the pharmaceutical market is devoted to anti-infective drugs. Of a $73 billion total global market of chiral drugs, antibiotics are the largest fraction ($20 billion) closely followed only by cardiovascular therapeutics ($17.5 billion).¹