Catalytic destruction of brominated aromatic compounds studied in a catalyst microbed coupled to gas chromatography/mass spectrometry

The capability of solid porous catalysts has been studied for the destruction or modification of halogenated aromatic compounds contaminating the pyrolysis oil of recycled plastics from electronic waste. A fast and simple experimental procedure is carried out using a micropyrolyser coupled to GC-MS in such a way that catalyst microbed was placed in the sample tube of the pyrolyser. The pyrolysis products of polycarbonate blended with a frequently applied flame retardant tetrabromobisphenol A (TBBPA) and epoxy resin containing TBBPA monomer units have been analysed, and the brominated components were compared with the thermal decomposition products of TBBPA and its diallyl ether. When TBBPA vapour passes through molecular sieve 4A a slight debromination and a partial cleavage of bisphenol A into phenols occur. Over molecular sieves of larger pore size (13X and NaY zeolite) an important decrease of TBBPA amount is observed indicating effective trapping ability of these catalysts of basic character for brominated aromatic compounds. A total chemical modification of the vapour was achieved by Al-MCM-41 catalyst that split TBBPA into bromophenols. Analogous results were obtained by carrying out similar experiments on diallyl ether of TBBPA. Moreover, it was revealed that brominated bisphenol A compounds are modified essentially the same way, either evaporated or evolved from a polycarbonate blend or produced by pyrolysis from an epoxy resin.     

The Effect of Isopropyl Alcohol and Non-Ionic Surfactant Mixtures on the Wetting of Porous Coated Paper

The influence of isopropyl alcohol and non-ionic surfactant solutions on aqueous droplet wetting behaviour on porous coated paper was determined. Paper coatings provide a micro- and nano-porous surface structure, which strictly speaking cannot be described in simple roughness terms as sub-surface lateral absorption directly impacts on the apparent contact angle. It is this very deviation from an idealised system that leads to novel wetting phenomena. Isopropyl alcohol and surfactant-based systems, both of which are commonly used in the printing industry, show differences in wetting behaviour, on both short and long timescales, with changes in the relative composition of the mixtures. Small variations of 0.1?wt% in surfactant concentration have a dramatic influence on the dynamic surface tension, and thus the wetting. It was observed that the wetting kinetics for isopropyl alcohol and surfactant solutions were different in terms of both wetting area and the penetration rate, even in cases where the dynamic surface tension of the solutions was kept the same. Different stages in the wetting and following drying processes could be observed with near infrared spectral imaging. In addition, the surfactant chemistries such as their degrees of hydrophilicity and molecular weights generated comparative differences in the wetting kinetics. The dominating factor affecting the wetting was, as expected, the solid?Cliquid interfacial energy defined on the practical porous substrate, which differed from the direct comparison with dynamic surface tension, thus exemplifying the deviation from idealised surface roughness behaviour when considering porous materials. An apparent ??equivalent?? surface roughness value for the porous material was determined, and it was seen that an increase in this equivalent parameter enhanced the rate of wetting behaviour with decreasing solution surface tension, and so also affected the wetting evolution. The wetting was enhanced by cavities in the coating layer, which were enlarged by the penetrating liquids.     

Large-Eddy Simulation of the Flow Over a Circular Cylinder at Reynolds Number 3900 Using the OpenFOAM Toolbox

The flow over a circular cylinder at Reynolds number 3900 and Mach number 0.2 was predicted numerically using the technique of large-eddy simulation. The computations were carried out with an O-type curvilinear grid of size of 300 × 300 × 64. The numerical simulations were performed using a second-order finite-volume method with central-difference schemes for the approximation of convective terms. A conventional Smagorinsky and a dynamic gt;kgt;-equation eddy viscosity sub-grid scale models were applied. The integration time interval for data sampling was extended up to 150 vortex shedding periods for the purpose of obtaining a fully converged mean flow field. The present numerical results were found to be in good agreement with existing experimental data and previously obtained large-eddy simulation results. This gives an indication on the adequacy and accuracy of the selected large-eddy simulation technique implemented in the OpenFOAM toolbox.     

Legendre Pseudospectral Approximation of Boussinesq Systems and Applications to Wave Breaking

In this paper, we propose a spectral projection of a regularized Boussinesq system for wave propagation on the surface of a fluid. The spectral method is based on the use of Legendre polynomials, and is able to handle time-dependent Dirichlet boundary conditions with spectral accuracy.The algorithm is applied to the study of undular bores, and in particular to the onset of wave breaking connected with undular bores. As proposed in [2], an improved version of the breaking criterion recently introduced in [5] is used. This tightened breaking criterion together with a careful choice of the relaxation parameter yields rather accurate predictions of the onset of breaking in the leading wave of an undular bore.     

Weakly driven anomalous diffusion in non-ergodic regime: an analytical solution

We derive the probability density of a diffusion process generated by nonergodic velocity fluctuations in presence of a weak potential, using the Liouville equation approach. The velocity of the diffusing particle undergoes dichotomic fluctuations with a given distribution gt;ψgt;(gt;τgt;) of residence times in each velocity state. We obtain analytical solutions for the diffusion process in a generic external potential and for a generic statistics of residence times, including the non-ergodic regime in which the mean residence time diverges. We show that these analytical solutions are in agreement with numerical simulations.     

Double-diffusive radiative magnetic mixed convective slip flow with Biot and Richardson number effects

This paper investigates combined heat and mass transfer by mixed magneto-convective flow of an electrically conducting flow along a moving radiating vertical flat plate with hydrodynamic slip and thermal convective boundary conditions. The governing transport equations are converted into a system of coupled nonlinear ordinary differential equations with prescribed boundary conditions using similarity variables developed by Lie group theory. The transformed nondimensional boundary value problem is then solved numerically with MAPLE13 quadrature. Excellent correlation with previous nonmagnetic, no-slip studies is achieved. Surface shear stress function and local Nusselt number (heat transfer gradient at the wall) are increased with Richardson number, whereas local Sherwood number is found to initially decrease then subsequently increase. The “thermally thick” scenario (Biot number > 0.1) is investigated and increasing Biot number is observed to enhance shear stress function (skin friction), local Nusselt number, and local Sherwood number. Increasing thermal radiation flux increases thermal boundary layer thickness as does increasing the magnetic field effect. Increasing hydrodynamic slip parameter reduces skin friction but enhances local Nusselt and Sherwood numbers. The study has applications in high-temperature polymeric synthesis and magnetic field flow control.     

Stereoselective palladium-catalyzed functionalization of homoallylic alcohols: a convenient synthesis of di- and trisubstituted isoxazolidines and β-amino-δ-hydroxy esters

Enantiopure, Boc-protected alkoxyamines 12 and 13, derived from the readily available homoallylic alcohols 4 via a reaction that involves either inversion or retention of configuration, undergo a diastereoselective Pd-catalyzed ring-closing carbonylative amidation to produce isoxazolidines 16/17 (≤50:1 diastereoisomer ratio (d.r.)) that can be readily converted into the N-Boc-protected esters of β-amino-δ-hydroxy acids and their γ-substituted homologues 37. The key carbonylative cyclization proceeds through an unusual syn addition of the palladium and the nitrogen nucleophile across the C=C bond (19→21), as revealed by the reaction of 15, which afforded isoxazolidine 18 with high diastereoselectivity.     

Advances in organic transistor-based biosensors: from organic electrochemical transistors to electrolyte-gated organic field-effect transistors

Organic electronics have, over the past two decades, developed into an exciting area of research and technology to replace classic inorganic semiconductors. Organic photovoltaics, light-emitting diodes, and thin-film transistors are already well developed and are currently being commercialized for a variety of applications. More recently, organic transistors have found new applications in the field of biosensors. The progress made in this direction is the topic of this review. Various configurations are presented, with their detection principle, and illustrated by examples from the literature.     

A low-finesse Fabry–Pérot interferometer for use in displacement measurements with applications in absolute gravimetry

A low-finesse Fabry–Pérot interferometer is used to determine long and fast displacements. Two corner cube reflectors form the traveling-wave cavity and one beam splitter couples the input collimated laser beam. Given the retro-directive property of corner cube reflectors, the cavity operates at the edge of stability over an extended scanning range. The in-line scheme with a single fixed optical component makes the proposed interferometer robust and easy to align and use. These characteristics are particularly useful in applications running in noisy environments, such as in on-field absolute gravimetry. Experimental data showing the performances reached in a transportable ballistic gravimeter are also presented.     

Synthesis and proton conductivity studies of azole functional organic electrolytes

As an attempt to produce azole functional proton conductors, organic electrolytes with triazole and tetrazole functional groups were synthesized via substitution reaction of 1,3,5-benzenetricarbonyl trichloride with aminotriazole and aminotetrazole. The samples were doped with triflic acid with molar ratios of 0.25 and 0.50. FTIR, nuclear magnetic resonance (NMR), and elemental analysis were used to characterize the resulting materials. Thermogravimetric analysis showed that the samples are thermally stable up to 150?°C. The effect of acid doping on proton conductivity was investigated with impedance spectrometer. Both pure samples and the doped ones revealed high proton conductivity. In anhydrous conditions (TMA)-TriTAgt;0.50gt; and TMA-TetTAgt;0.50gt; have proton conductivities of 1.8 and 19?mS/cm at 150?°C, respectively. Solid-state NMR studies revealed that there are three different types of hydrogen-bonded acidic proton in the systems. Moreover, these different types of acidic protons present at different ratio in triazole and tetrazole systems.