Preparation of new copolymer (polystyrene/TMSPM grafted on DDA-fractionated algerian montmorillonite) hybrid organoclay by radical copolymerization: structural study,thermal stability and hydrophobicity area

Journal of Thermal Analysis and Calorimetry - Polystyrene/organo-Algerian montmorillonite hybrid material was prepared by radical copolymerization of styrene monomer in the presence of the double...     

A Carbon Paste Electrode Modified by Bentonite and l‐Cysteine for Simultaneous Determination of Ascorbic and Uric Acids: Application in Biological Fluids

A novel modification of a paste carbon electrode by Bentonite (Bent) and l‐Cysteine (l‐Cyst) was carried out for uric acid (UA) and ascorbic acid (AA) detection and quantification. Morphological and compositional characterization of the electrode surface were carried out using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopic analysis (EDS). Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were used to analyze UA and AA. The obtained sensor shows a good stability, sensibility, selectivity, and regeneration ability. Accordingly, the limit of detection (LOD) is found to be 0.031 μm and 9.6 μm for UA and AA, respectively. A good linearity in the range of 0.1 to 100 μm for UA and 10 to 1000 μm for AA was obtained. The peak‐to‐peak separation of UA‐AA (ΔE _UA‐AA) was determined to be 330 mV. In addition, the sensor is applied successfully to monitor UA and AA in serum samples.     

Ab initio calculations of structural,electronic, optical and thermodynamic properties of alkaline earth tellurides BaxSr1−XTe

Structural, electronic and thermodynamic properties of SrTe and BaTe compounds and their ternary mixed crystals Ba_xSr_1−xTe in the rock-salt structure have been studied with density functional theory (DFT), whereas the optical properties have been obtained by using empirical methods such as the modified Moss relation. The exchange-correlation potential was calculated using the generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof (PBE) and the local density approximation (LDA) of Teter–Pade (TP). In the present work, we used the virtual-crystal approximation (VCA) to study the effect of composition (x). The calculated lattice parameters at equilibrium volume and the bulk modulus for x=0 and x=1 are in good agreement with the literature data. Furthermore, the Ba_xSr_1−xTe alloys are found to be an indirect band gap semiconductor. In addition, we have also predicted the heat capacities (C_V), the entropy(S), the internal energy (U) and the Helmholtz free energy (F) of the parent compounds SrTe and BaTe.     

Realization and characterization of flexible supercapacitors based on doped graphene electrodes

Journal of Solid State Electrochemistry - High energy consumption leads to the development of various energy types. As a result, the storage of these different types of energy becomes a key issue....     

Insight into the structural,electronic and elastic properties of AInQ2 (A: K,Rb and Q: S,Se, Te) layered structures from first-principles calculations

First-principles calculations were performed to explore the structural, elastic and electronic properties of the ternary indium chalcogenides AInQ₂ (A: K, Rb and Q: S, Se, Te) in both monoclinic and triclinic phases. This study is carried out by using the first-principles pseudopotential plane-wave (PP–PW) method as implemented in CASTEP code. Both the generalized gradient approximation of Perdew–Burke–Ernzerhof scheme (GGA–PBE) and the Heyd–Scuseria–Ernzerhof (HSE06) hybrid functional were used to treat the exchange-correlation interactions. In order to confirm the previous reports and to understand the effect of symmetry in determining the physical properties of these layered materials we have calculated the structural and the electronic properties at the equilibrium lattice constant for both the systems. The single-crystal elastic constants C_{i j} are calculated using the stress-strain approach. The elastic moduli of the polycrystalline aggregates and their related properties are obtained in the framework of Voigt–Reuss–Hill approximations. Electronic band structure indicates the semiconducting behaviour with a direct band gap at Γ–Γ. The results obtained from the (HSE06) hybrid functional are in excellent agreement with the available experimental data and computed results for the monoclinic and triclinic structures.