Oxidative degradation of phenol in aqueous media using ultrasound

The degradation of phenol with ultrasound and the influence of several parameters - hydrostatic pressure, nature of the dissolved gas, frequency of the ultrasound - have been studied. Primary degradation products are dihydroxy benzenes and quinones. These products are further degraded upon time into low molecular carboxylic acids. COD reduction can be increased by the addition of Raney nickel. Based on the determination of the degradation products by HPLC and HPICE, a reaction scheme can be suggested.     

Multi-levels inverse identification of physical parameters of porous materials

The identification of the physical parameters of porous materials presents an important field of research, in which many identification methods are developed. One of those methods is presented in this paper. In fact, a multi-levels inverse identification method is developed in order to estimate these physical parameters. The proposed method is based on the minimization of the difference between a reference acoustic absorption coefficient of a porous material and the computed values. The minimization is done according three levels, in each level an acoustic model of porous material is used to evaluate one or two parameters. Finally, the five physical parameters of the porous materials are deduced. The proposed method is applied to Polyurethane foam material. The obtained results are satisfying with small values of errors and with estimated acoustic absorption coefficient reaching the reference one.     

Co-adsorption of carboxymethyl-cellulose and cationic surfactants at the air-water interface

We investigated the interaction between an anionic polyelectrolyte (carboxymethylcellulose) and cationic surfactants (DTAB, TTAB, and CTAB) at the air/water interface, using surface tension, ellipsometry, and Brewster angle microscopy techniques. At low surfactant concentration, a synergistic phenomenon is observed due to the co-adsorption of polyelectrolyte/surfactant complexes at the interface, which decreases the surface tension. When the surfactant critical aggregation concentration (cac) is reached, the adsorption saturates and the thickness of the adsorbed monolayer remains constant until another characteristic surfactant concentration, C0, is reached, at which all the polymer charges are bound to surfactant in bulk. Above C0, the absorbed monolayer becomes much thicker, suggesting adsorption of bulk aggregates, which have become more hydrophobic due to charge neutralization.     

Aggregate formation in aqueous solutions of carboxymethylcellulose and cationic surfactants

The addition of cationic surfactants to an aqueous solution of an anionic polymer, carboxymethylcellulose (carboxyMC), causes the spontaneous formation of aggregates in a certain range of concentrations. Here we studied two surfactants, dodecyl and hexadecyl trimethylammonium bromide (DTAB and CTAB, respectively). Using different techniques (light scattering, potentiometry, viscosimetry, and zetametry), we found that a simple lengthening of the surfactant tail length by four CH2 groups drastically changes the aggregate morphology, size, and charge. We explored in detail how the surfactant and polymer concentrations act on these systems.     

Effect of organic modifier and temperature on the resolution of betamethasone and dexamethasone using a porous graphitic carbon column: application to their identification and confirmation in human urine by LC-ESI-MS/MS

The effects of temperature, organic modifier and the type of acid on the retention factor, the resolution and peak shape of betamethasone and dexamethasone are described. The study is performed using narrow bore porous graphitic carbon (PGC) columns online with diode-array detector (DAD) and ESI MS/MS. The results show that temperature affects the retention behaviour of the two compounds and ACN yields the best separation while no effect is obtained by changing the type of organic acid. The developed method is applied for the confirmation of dexamethasone and betamethasone in human urine.     

Classification systems based on rough sets under the belief function framework

In this paper, we present two classification approaches based on Rough Sets (RS) that are able to learn decision rules from uncertain data. We assume that the uncertainty exists only in the decision attribute values of the Decision Table (DT) and is represented by the belief functions. The first technique, named Belief Rough Set Classifier (BRSC), is based only on the basic concepts of the Rough Sets (RS). The second, called Belief Rough Set Classifier, is more sophisticated. It is based on Generalization Distribution Table (BRSC-GDT), which is a hybridization of the Generalization Distribution Table and the Rough Sets (GDT-RS). The two classifiers aim at simplifying the Uncertain Decision Table (UDT) in order to generate significant decision rules for classification process. Furthermore, to improve the time complexity of the construction procedure of the two classifiers, we apply a heuristic method of attribute selection based on rough sets. To evaluate the performance of each classification approach, we carry experiments on a number of standard real-world databases by artificially introducing uncertainty in the decision attribute values. In addition, we test our classifiers on a naturally uncertain web usage database. We compare our belief rough set classifiers with traditional classification methods only for the certain case. Besides, we compare the results relative to the uncertain case with those given by another similar classifier, called the Belief Decision Tree (BDT), which also deals with uncertain decision attribute values.     

Effect of defects and surface anchoring on the phase behavior of chiral smectic liquid crystals

The influence of defects and surface effects on the stability of phenomena accompanying phase transitions, mainly coexistence phenomenon, has been studied. Experimental measurements were carried out by varying the cell thickness and using simple experimental on chiral smectic liquid crystal product. The analysis of the results with different cell thickness leads us to interpret the anomaly shown by our product related to impact of defects and surface effects. Moreover, the phase transition is affected by the trace of defects for thick cell and by the surface effect for thin cell. These effects have the same role as an electric local field which can induce phase transition.     

Solution of the Spinless Salpeter Equation with a Time-Dependent Linear Potential

We derive the general solution of the semi-relativistic spinless Salpeter equation in the presence of a time-dependent linear potential via the Lewis–Riesenfeld framework and using two forms of the invariant. For comparison, we reobtain the solution in the momentum-space directly by applying a time-momentum transformation to the involved partial differential equation. We also investigate the classical-quantum correspondence for the model in the case of time-periodic force using a momentum-space Gaussian wave-packet.