Reactivity of polychlorophenylmercury compounds with 1,10-phenanthroline

The action of 1,10-phenanthroline (phen) on the THF solutions of RHgCl (R = 2,5-C₆H₃Cl₂; 2,3,4? and 2,4,6-C₆H₂Cl₃; 2,3,4,5?, 2,3,4,6?, and 2,3,5,6-C₄HCl₄ and C₆Cl₅) gives RHgCl (phen) when R contains two chlorine substituents in ortho (R = 2,4,6-C₆H₂Cl₃; 2,3,4,6?, and 2,3,5,6-C₆HCl₄ and C₆Cl₅), but the symmetrisation reaction occurs when R = 2,5-C₆H₃Cl₂; 2,3,4-C₆H₂Cl₃ and 2,3,4,5-C₆HCl₄. The action of phen on HgR₂ only gives HgR₂ (phen) when R = 2,3,4,5-C₆HCl₄. Compounds of the type RHgMe do not react with phen. These results indicate that steric citects are as important as the electronegativity of R in the formation of tetracoordinated mercury compounds.     

Modelling of patterns during adsorption of chiral molecules on metallic surfaces

A gas lattice model and Monte Carlo simulations have been used to model the behavior of chiral molecules adsorbed on clean metallic surfaces. The aim of this work is to characterize how adsorbed molecules organize on the surface, what their footprints are and which are the main mechanisms of interaction responsible for the different patterns observed. These patterns have already been depicted and illustrated by other authors through different techniques and here some of them have been simulated using simple models for adsorption. In these models, both inhibition effects (such as blockage of neighboring sites to simulate steric effects) and promotion of neighboring sites (to simulate adsorbate-adsorbate and adsorbate-substrate interactions) are used. These adsorption rules try to mimic the enantiomeric character of the adsorbed species.     

Energy change to insertion of inclusions associated with a diffusive/convective steady‐state heat conduction problem

The topological derivative concept has been successfully applied in many relevant physics and engineering problems. In particular, the topological asymptotic analysis has been fully developed for a wide range of problems modeled by partial differential equations. In this paper, the topological asymptotic analysis of the energy shape functional associated with a diffusive/convective steady‐state heat equation is developed. The topological derivative with respect to the nucleation of a circular inclusion is derived in its closed form with help of a non‐standard adjoint state. Finally, we provide the estimates for the remainders of the topological asymptotic expansion and perform a complete mathematical justification for the derived formulas. The obtained result is new and can be applied in the context of topology design of heat sinks, for instance. Copyright © 2015 John Wiley & Sons, Ltd.     

A review on the electrochemical production of chlorine dioxide from chlorates and hydrogen peroxide

Chlorine dioxide is one of the most interesting oxidants because it combines a strong capacity of oxidation with low formation of hazardous byproducts such as chlorinated organics during its application. Because of that, it is widely used in disinfection of drinking water and, currently, it is aimed to be used in the disinfection of surfaces or buildings. Although it is usually produced by the chemical interaction of chlorite with hypochlorite/chlorine or hydrochloric acid, one interesting alternative for its production is the combination in strongly acidic media of chlorate and hydrogen peroxide. Both compounds are known to be efficiently manufactured with electrochemical technology, opening the possibility of a complete electrochemical process to produce this important oxidant. This review summarizes the recent progress in the electrochemical production of the two raw materials, as well as the complete electrochemical production of chlorine dioxide, not only paying attention to the scientific literature but, most importantly, to recent patents, trying to see in which technology readiness level are each of the technologies and what are the elements of the value chain required for a complete implementation of the technology.     

Weak Ferromagnetism and Field-Induced Spin Reorientation in K2V3O8

Magnetization and neutron diffraction studies of the 2D S = 1/2 antiferromagnet, K2V3O8, indicate an ordered state exhibiting weak ferromagnetism and field-induced spin reorientations. Of particular interest is the behavior in a basal plane magnetic field where a unique spin reorientation is observed in which the spins rotate from the easy c axis to the basal plane while remaining normal to the applied field. The experimental observations are well described by a two spin exchange model incorporating Heisenberg and Dzyaloshinskii-Moriya interactions with an additional c-axis anisotropy.     

Probing Phonon Scattering Sites in the Thermoelectric Clathrate Eu8Ga16Ge30

The low thermal conductivity of the Thermoelectric Clathrates Eu₈Ga₁₆Ge₃₀ and Sr₈Ga₁₆Ge₃₀ has been attributed to rattling atoms (Eu or Sr) in the Eu2/Sr2 sites. The low Einstein temperature obtained using XAFS for the nearest neighbor Eu-Ga/Ge bonds at the Eu2 sites is consistent with the model. However, the comparable Einstein temperature for the Eu1 site indicates that Eu1 is also a rattler. The fit also confirms that the Eu2 is displaced along either the y or z axis ～ 0.45Å in agreement with neutron diffraction.     

Biomimetic norfloxacin sensors made of molecularly-imprinted materials for potentiometric transduction

A biomimetic sensor for norfloxacin is presented that is based on host-guest interactions and potentiometric transduction. The artificial host was imprinted into polymers made from methacrylic acid and/or 2-vinyl pyridine. The resulting particles were entrapped in a plasticized poly(vinyl chloride) (PVC) matrix. The sensors exhibit near-Nernstian response in steady state evaluations, and detection limits range from 0.40 to 1.0???g?mL^?1, respectively, and are independent of pH values at between 2 and 6, and 8 and 11, respectively. Good selectivity was observed over several potential interferents. In flowing media, the sensors exhibit fast response, a sensitivity of 68.2?mV per decade, a linear range from 79???M to 2.5?mM, a detection limit of 20???g?mL^?1, and a stable baseline. The sensors were successfully applied to field monitoring of norfloxacin in fish samples, biological samples, and pharmaceutical products.

Disposable solid state probe for optical screening of chlorpromazine

We are presenting a simple, low-cost and rapid solid-state optical probe for screening chlorpromazine (CPZ) in aquacultures. The method exploits the colourimetric reaction between CPZ and Fe(III) ion that occurs at a solid/liquid interface, the solid layer consisting of ferric iron entrapped in a layer of plasticized PVC. If solutions containing CPZ are dropped onto such a layer, a colour change occurs from light yellow to dark pink or even light blue, depending on the concentration of CPZ. Visual inspection enables the concentration of CPZ to be estimated. The resulting colouration was also monitored by digital image collection for a more accurate quantification. The three coordinates of the hue, saturation and lightness system were obtained by standard image processing along with mathematical data treatment. The parameters affecting colour were assessed and optimized. Studies were conducted by visible spectrophotometry and digital image acquisition, respectively. The response of the optimized probe towards the concentration of CPZ was tested for several mathematical transformations of the colour coordinates, and a linear relation was found for the sum of hue and luminosity. The limit of detection is 50???M (corresponding to about 16???g per mL). The probe enables quick screening for CPZ in real water samples with prior sample treatment.

Dynamic statistical properties of squeezed coherent state superpositions

We carried out a study of statistical properties of a squeezed coherent state superposition (SCSS) evolving under a thermal reservoir at zero and finite temperature. Our results reveal some peculiarities not noticed by previous studies, which were mainly focused on ideal (lossless) properties of SCSS. Our main results indicate the existence of realistic parameters for which SCSS, at zero absolute, remains sub-Poissonian or squeezed asymptotically, while, at finite temperature, we found that SCSS only loses its squeezing or sub-Poissonian character at large times as compared with the time needed to the SCSS become a complete mixture.