Preparation and evaluation of lauryl methacrylate monoliths with embedded silver nanoparticles for capillary electrochromatography

In this article, capillary columns constituted by lauryl methacrylate monoliths with embedded silver nanoparticles (AgNPs) were developed and tested. Two incorporation approaches of AgNPs in monoliths were explored. The AgNPs were either photogenerated in situ during polymerization of the monolith by UV irradiation, or incorporated to the polymerization mixture (ex situ). The influence of the AgNP concentration on the morphological and chromatographic properties of the polymer matrix was investigated, and both the in situ and ex situ approaches were comparatively discussed. The morphology of the monoliths was characterized by electron microscopic techniques, and their electrochromatographic performance was also evaluated with test mixtures of neutral compounds (sterols, fatty acid methyl esters, tocopherols, and polyaromatic hydrocarbons).     

Vortex generation by a convective instability in a cylindrical annulus non-homogeneously heated

In this work we present a convective instability as the mechanism for generating vertical vortices in a cylindrical annulus non-homogeneously heated from below. Assuming axisymmetry, we study thermal and geometrical conditions under which stable vortical structures are found. The structure of these vortices appears to be qualitatively similar to that of dust devils.     

Diastereoselective arylation of enantiopure 3-bromopiperidin-2-one derived from (R)-(−)-2-phenylglycinol with organocuprate reagents

The diastereoselective substitution of 3-bromolactam derived from (R)-(−)-2-phenylglycinol with a variety of arylcuprate reagents is presented. The stereochemical outcome of the substitution reaction is discussed. The method provides an efficient and straightforward route to enantiopure 3-arylpiperidines.     

A C2‐continuous high‐resolution upwind convection scheme

A bounded upwinding scheme for numerical solution of hyperbolic conservation laws and Navier–Stokes equations is presented. The scheme is based on convection boundedness criterion and total variation diminishing stability criteria and developed by employing continuously differentiable functions. The accuracy of the scheme is verified by assessing the error and observed convergence rate on 1‐D benchmark test cases. A comparative study between the new scheme and conventional total variation diminishing/convection boundedness criterion‐based upwind schemes to solve standard nonlinear hyperbolic conservation laws is also accomplished. The scheme is then examined in the simulation of Newtonian and non‐Newtonian fluid flows of increasing complexity; a satisfactory agreement has been observed in terms of the overall behavior. Finally, the scheme is used to study the hydrodynamics of a gas‐solid flow in a bubbling fluidized bed. Copyright © 2013 John Wiley & Sons, Ltd.     

Radiation effect on thermoluminescence and electron paramagnetic resonance (EPR) of pink beryl

Morganite, a pink beryl with the chemical formula Be₃Al₂Si₆O₁₈, was investigated in terms of its thermally stimulated luminescence (TL) and electron paramagnetic resonance (EPR) properties due to point defects. Atomic hydrogen H°-centers were induced by γ-radiation and shown to be responsible for a 165°C TL peak. The Fe³⁺-center concentration was found to increase with γ-dose, observed by both TL and EPR measurements, decreasing with thermal treatments beyond 250°C. A mechanism for emission around 315°C is proposed.     

Topological invariants of isolated complete intersection curve singularities

In this paper we present some formulae for topological invariants of projective complete intersection curves with isolated singularities in terms of the Milnor number, the Euler characteristic and the topological genus. We also present some conditions, involving the Milnor number and the degree of the curve, for the irreducibility of complete intersection curves.     

Covering point sets with two disjoint disks or squares

We study the following problem: Given a set of red points and a set of blue points on the plane, find two unit disks C_R and C_B with disjoint interiors such that the number of red points covered by C_R plus the number of blue points covered by C_B is maximized. We give an algorithm to solve this problem in O(n^8/3log²n) time, where n denotes the total number of points. We also show that the analogous problem of finding two axis-aligned unit squares S_R and S_B instead of unit disks can be solved in O(nlogn) time, which is optimal. If we do not restrict ourselves to axis-aligned squares, but require that both squares have a common orientation, we give a solution using O(n³logn) time.