Photodegradation of Decabromo Diphenyl Ether Flame Retardant in Poly (Acrylonitrile Butadiene Styrene) (ABS)

Abstract

Decabromodiphenylether (DBDE) is a brominated flame retardant which belongs to the group of polybromodiphenylethers (PBDEs) often used as a fire resistant additive in various well known polymeric systems like polystyrene, poly(acrylonitrile-butadiene-styrene) (ABS), polypropylene, etc. This compound can be considered as a persistent organic pollutant and presents certain risks for the environment owing to the fact that it is bioaccumulable and not biodegradable. A detailed investigation, described here, was carried out on the effect of ultraviolet/visible radiation on DBDE in ABS with the aim to study the photolytic reactions of this molecule in the solid state, in order to improve the economic and ecological treatment of brominated plastic waste from waste electrical and electronic equipment (WEEE). This study presents new aspects of the photochemical degradation of DBDE/ABS systems in the solid state. The photodegradation of DBDE in ABS was followed by Fourier transform infrared spectroscopy (FTIR) as well as by thermogravimetrical analysis (TGA). Good agreement was obtained for the results of both analytical methods in terms of the overall photolysis of DBDE.     

Existence and Asymptotic Behavior of Solutions to Semilinear Wave Equations with Nonlinear Damping and Dynamical Boundary Condition

Our aim in this article is to study a nonautonomous semilinear wave equation with nonlinear damping and dynamical boundary condition. First we prove the existence and uniqueness of global bounded solutions having relatively compact range in the natural energy space. Then, by deriving an appropriate Lyapunov energy, we show that if the exponent in the ?ojasiewicz-Simon inequality is large enough (depending on the damping), then weak solutions converge to equilibrium.     

Preparation, purification and quality control of 131I-m-iodobenzylguanidine (MIBG)*

Iodination of meta-iodobenzylguanidine was carried out at optimum conditions. The labeling yield at these conditions was more than 95%. Further purification of the prepared compound increased the radiochemical purity to more than of 99.5%, this high purity was revealed in the quality of the images resulting from the use of the prepared compounds.     

The electrochemical performance of AB3-type hydrogen storage alloy as anode material for the nickel metal hydride accumulators

For the purpose of lowering the cost of metal hydride electrode, the La of LaY₂Ni₉ electrode was replaced by Ce. The electrochemical performances of the CeY₂Ni₉ negative electrode, at a room and different temperatures, were compared with the parent alloy LaY₂Ni₉. At room temperature during a long cycling, the evolution of the electrochemical capacity—the diffusivity indicator (\( \frac{D_{\mathrm{H}}}{a^2} \))—the exchange current density, and the equilibrium potential were determined. At different temperatures, the electrochemical characterization of this alloy allowed the estimation of the enthalpy, the entropy, and the activation energy of the hydride formation. The evolution of the high-rate dischargeability was also evaluated at different temperatures. Compared with the parent LaY₂Ni₉ alloy, CeY₂Ni₉ exhibits an easy activation and good reaction reversibility. This alloy also conserves a good lifetime during a long-term cycling. A lower activation energy determined for this alloy corresponds to an easy absorption of hydrogen into this new alloy.     

Elucidation of Antioxidant Compounds in Moroccan Chamaerops humilis L. Fruits by GC–MS and HPLC–MS Techniques

The aim of this study was to characterize the phytochemical content as well as the antioxidant ability of the Moroccan species Chamaerops humilis L. Besides crude ethanolic extract, two extracts obtained by sonication using two solvents with increased polarity, namely ethyl acetate (EtOAc) and methanol-water (MeOH-H₂O) 80:20 (v/v), were investigated by both spectroscopy and chromatography methods. Between the two extracts, the MeOH-H₂O one showed the highest total polyphenolic content equal to 32.7 ± 0.1 mg GAE/g DM with respect to the EtOAc extract (3.6 ± 0.5 mg GAE/g DM). Concerning the antioxidant activity of the two extracts, the EtOAc one yielded the highest value (1.9 ± 0.1 mg/mL) with respect to MeOH-H2O (0.4 ± 0.1 mg/mL). The C. humilis n-hexane fraction, analyzed by GC–MS, exhibited 69 compounds belonging to different chemical classes, with n-Hexadecanoic acid as a major compound (21.75%), whereas the polyphenolic profile, elucidated by HPLC–PDA/MS, led to the identification of a total of sixteen and thirteen different compounds in both EtOAc (major component: ferulic acid: 104.7 ± 2.52 µg/g) and MeOH-H₂O extracts (major component: chlorogenic acid: 45.4 ± 1.59 µg/g), respectively. The attained results clearly highlight the potential of C. humilis as an important source of bioactive components, making it a valuable candidate to be advantageously added to the daily diet. Furthermore, this study provides the scientific basis for the exploitation of the Doum in the food, pharmaceutical and nutraceutical industries.     

Separation of 99mTc from 99Mo by Using TOPO — Kerosene Supported Liquid Membrane

Transport of ^99mTcO₄ ^– ions across TOPO-kerosene based supported liquid membrane was investigated at different concentrations of phosphoric acid as a feed solution and different concentrations of TOPO in the membrane, where 0.9% NaCl aqueous solution was used as a stripping solution. The flux of TcO₄ ^– ions across this liquid membrane varied with the concentration of both H₃PO₄ and TOPO. The best permeability coefficient was obtained at concentrations, [H₃PO₄] = 3 mole·l^–1 and [TOPO] = 0.5 mole·l^–1 (P = 2.08·10^–9 m²·s^–1). The results were utilized for the separation of ^99mTc from ⁹⁹Mo, where a selective and effective separation was obtained since no ⁹⁹Mo transport across this liquid membrane was noticed while a high rate of ^99mTc transport took place.     

Electrophoresis Poly(Dimethylsiloxane)/Glass Chips with Integrated Active Cooling for Quantification of Amino Acids

Abstract

The objective of this work was to develop and characterize a poly(dimethylsiloxane) device with an integrated active cooling function able to carry out capillary electrophoresis separations. Polymer-based microdevices are indispensable to recent advances in biomedical analysis. In particular, they have been applied to many microfluidic platforms owing to their low cost, ease of fabrication, and versatility in preparing complex microstructures. However, when applied to capillary electrophoresis separations, polymer microfluidic structures present an inherent disadvantage compared to glass and Si structures; they have a lower thermal conductivity than glass and Si. Although miniaturized devices allow operation at high electric fields, they face separation efficiency limitations due to Joule heating. There is, therefore, a strong need of developing capillary electrophoresis microfluidic structures with active cooling in order to operate at a higher electric field and potentially increase separation efficiency in these microdevices. A poly(dimethylsiloxane)/glass hybrid microfluidic capillary electrophoresis system is presented, where Joule heating was minimized by using an integrated active cooling function. Two poly(dimethylsiloxane) slabs with embedded microfluidic structures were irreversibly sealed on both sides of a thin glass slide. The top poly(dimethylsiloxane) slab was used to carry out capillary electrophoresis separations, whereas the bottom poly(dimethylsiloxane) slab was employed to cool down the buffer solution used during the capillary electrophoresis separation. As demonstrated on current versus voltage plots and on capillary electrophoresis electropherograms, capillary electrophoresis separation was able to be operated at a higher electric field when using the cooling function. The cooling rate was adjustable by varying the flow rate and the initial temperature of the liquid flowing in the cooling microfluidic structure.