Enthalpies molaires d'exces des melanges binaires thiophene et diethylsulfide avec n-alcanes

The excess molar enthalpy of thiophen and diethylsulfid with some n alkanes have been measured at 303.15 K and 1 atm. A Redlich—Kister type equation was used to represent and correlate the results. Empirical equations of group contribution model, disquac have been applied for the binaries systems.This revised version was published online in November 2005 with corrections to the Cover Date.     

Efficient Approach for the Synthesis of Novel Functionalized Isoxazolines from Limonene

New functionalized isoxazolines were effeciently and easily prepared from limonene. The procedure involves a peri‐ and regioselective 1,3‐dipolar cycloaddition of nitrile oxides on the monoterpene external double bond, followed by a highly chemoselective RuCl₃‐NaIO₄ oxidative cleavage of the internal one. All the newly prepared isoxazolyl‐ketoacids were fully characterized from their spectroscopic data.     

ZnO–Al2O3–CeO2–Ce2O3 mixed metal oxides as a promising photocatalyst for methyl orange photocatalytic degradation

In this research article, ZnO–Al₂O₃–CeO₂–Ce₂O₃ mixed metal oxides phases were prepared by calcination of Zn–Al/Ce–CO₃ layered double hydroxides (LDH) precursors, and evaluated for the photocatalytic degradation of methyl orange (MO) as a model textile dye from aqueous solution under UV irradiation. First, Zn–Al–CO₃ and a series of Zn–Al/Ce–CO₃ with different Ce content (5, 10, 15, 20%) were synthesized through co-precipitation method at Zn/(Al+Ce) molar ratio (r) of 3, then subjected to calcination at 500 °C for 6 h. Samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray analysis and pH point of zero charge. The experimental results of the photodegradation reveal that the photocatalyst developed from Zn–Al–Ce10%-CO₃ LDH exhibits the highest photocatalytic activity, with a degradation efficiency of 99.8% after 300 min of irradiation. This performance was mainly ascribed to the presence of difference state of Ce, leading a highest separation efficiency of electrons and holes. The recycling tests suggests a much high photostability and reusability of the photocatalyst.     

Optimal control of a quasi-variational obstacle problem

We consider an optimal control where the state-control relation is given by a quasi-variational inequality, namely a generalized obstacle problem. We give an existence result for solutions to such a problem. The main tool is a stability result, based on the Mosco-convergence theory, that gives the weak closeness of the control-to-state operator. We end the paper with some examples.     

Dynamics of solitons in plasmas for the complex KdV equation with power law nonlinearity

This paper obtains the 1-soliton solution of the complex KdV equation with power law nonlinearity. The solitary wave ansatz is used to carry out the integration. The soliton perturbation theory for this equation is developed and the soliton cooling is observed for bright solitons. Finally, the dark soliton solution is also obtained for this equation.     

BER calculation in DS/CDMA over Rayleigh fading channel with power control error using fuzzy systems

We propose in this work, a simple method to calculate the bit error rate (BER) performance of a direct sequence code division multiple access (DS/CDMA) system over a Rayleigh multipath fading with power control error for both coherent and noncoherent reception, the RAKE structure receivers under consideration employ despreading sequences weighted (WDS) by exponential chip weighting waveforms. Numerical results show that the proposed approach reduce complexity and time of BER’s computing, then its performance does not undergo any degradation.     

New approach for the existence of pseudo almost periodic solutions for some second order differential equation with piecewise constant argument

The following equation d²/dt²(x(t)+px(t-1))=qx(2[(t+1)/2])+f(t)${\mathrm{d}}^2/\mathrm{d}{t}^2(x(t)+\mathit{px}(t-1))=\mathit{qx}(2[(t+1)/2])+f(t)$ is considered and necessary and sufficient conditions are given in order to ensure the existence and uniqueness of pseudo almost periodic solutions.     

Prospecting Quantum Correlations and Examining Teleportation Fidelity in a Pair of Coupled Double Quantum Dots System

The topic of improving the ability of quantum systems to retain non-local features and enhance the efficiency of quantum protocols continues. This study delves into the thermal investigation of quantum correlations and teleportation fidelity of a two-qubit teleported state using excess electrons in a coupled double quantum dots system as a quantum channel. The study employs three reliable quantum quantifiers to prospect the resourcefulness and non-classicality of the system. The findings suggest that preserving quantum correlations and optimizing teleportation fidelity require minimizing tunneling coupling and maximizing Coulomb interaction. The study has significant implications for quantum physics and its practical applications in quantum information processing.     

Transport of kaolinite colloids through quartz sand: influence of humic acid, Ca(2+), and trace metals

To evaluate the risk of contaminant transport by mobile colloids, it seems essential to understand how colloids and associated pollutants behave during their migration through uncontaminated soil or groundwater. In this study, we investigated at pH 4 the influence of flow velocity, humic acid, solution Ca(2+) concentrations, and trace metals (Pb(2+), Cu(2+)) on the transport and deposition of kaolinite particles through a pure crystalline quartz sand as porous medium. A short-pulse chromatographic technique was used to measure colloid deposition. Adsorption of humic acid to the kaolinite increase its negative surface charge and then decrease colloid deposition. Experiments with different flow rates showed that humic-coated kaolinite colloid deposition followed a first-order kinetic rate law. The deposition rate coefficients of humic-coated kaolinite colloids increase with increasing Ca(2+) concentration in the suspension. The effect of trace metals on the mobility is studied by injecting two suspensions with different concentrations of Pb(2+) and Cu(2+). At very low cation concentration, the fraction of colloids retained is low and roughly independent of the nature of divalent cations. At high concentration, the deposition is higher and depends on the affinity of divalent cations toward humic-coated kaolinite colloids.     

Effect of surface‐grafted ionic groups on the performance of cellulose‐fiber‐reinforced thermoplastic composites

The influence of the surface chemistry of the cellulose fiber and polymer matrix on the mechanical and thermal dynamic mechanical properties of cellulose‐fiber‐reinforced polymer composites was investigated. The cellulose fiber was treated either with a coupling agent or with a coupling‐agent treatment followed by the introduction of quaternary ammonium groups onto the fiber surface, whereas the polymer matrix, with opposite polar groups such as polystyrene incorporated with sulfonated polystyrene and poly(ethylene‐co‐methacrylic acid), was compounded with the fiber. The grafting of the fiber surface was investigated with Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. Experimental results showed that an obvious improvement in the mechanical strength could be achieved for composites with an ionic interface between the fiber and the polymer matrix because of the adhesion enhancement of the fiber and the matrix. The improved adhesion could be ascribed to the grafted ionic groups at the cellulose‐fiber surface. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2022–2032, 2003