Synthesis and characterization of highly ordered mesoporous nanomaterials Al-MCM-41 and Al-SBA-15 from bentonite as efficient catalysts for the production of biodiesel MELA and EELA

Research on Chemical Intermediates - Low-cost Al-MCM-41 and Al-SBA-15 mesoporous materials are successfully synthesized from bentonite as silicon and aluminum sources instead of laboratory reagents...     

Batch and continuous fixed-bed column adsorption of Cs+ and Sr2+ onto montmorillonite–iron oxide composite: Comparative and competitive study

A montmorillonite–iron oxide composite (MIOC) was prepared to assess its effectiveness in the removal of Cs⁺ and Sr²⁺ from aqueous solution. A comparative and competitive adsorption study was conducted in single and binary systems. Used materials have been characterized by X-ray diffraction (XRD) and Infrared spectroscopy. Adsorption of Cs⁺ and Sr²⁺ as a function of contact time and pH was investigated, adsorption data of single metal solutions were well fitted to the Freundlich–Langmuir isotherm models. Equilibrium isotherms for the binary removal of Cs⁺ and Sr²⁺ by MIOC have been analyzed by using non modified and extended Langmuir models with a satisfactory R ² values. Neutral solution pH was found to be favorable for both single and binary systems. The adsorption model analysis revealed that MIOC was more selective for Sr than Cs. The maximum adsorption capacities for individual Cs⁺ and Sr²⁺ solutions were 52.6 and 55.5 mg g^?1, respectively. While the maximum uptakes in the binary system were 41.6 and 47.6 mg g^?1 for Cs⁺ and Sr²⁺, respectively. Column adsorption experiments were carried out at room temperature under the effect of various operating parameters such as bed depth, initial cation concentration and flow rate, Breakthrough curves were well fitted to the Thomas model. Desorption experiments were also conducted to assess the possibility for the reuse of adsorbent and the recovery of cations.     

Investigations of the Effects of Xanthan and Sodium Caseinate on the Formation and Stability of an Oil-in-Water Emulsion Stabilized by a Nonionic Surfactant Using a Response Surface Method

Effects of xanthan and sodium caseinate concentrations on the rheological properties and stability of an oil-in water emulsion stabilized by a nonionic surfactant (Tween 20) were investigated. In order to evaluate the influence of component concentrations on the emulsion properties, a response surface method was applied. It was shown by polynomial simulation and modelization of responses of storage modulus and creaming index that in absence of Tween 20, the oily droplets were flocculated by bridging of sodium caseinate macromolecules, when those are insufficient to cover the entire interface. Additionally, it was noted that xanthan reinforces the polymeric network in the aqueous phase when the caseinate is not moved toward the phase. On the other hand, in presence of nonadsorbed caseinate, the polysaccharide develops segregative interactions by thermodynamic incompatibility. These nonadsorbed macromolecules can also flocculate the fatty globules by depletion.     

Inhibitive effect of imidazopyridine derivative towards corrosion of C38 steel in hydrochloric acid solution

The effect of adding 2-phenylimidazo[1,2-a]pyridine-3-carbaldehyde derivative named (P2), newly synthesized on the electrochemical behavior of C38 steel in molar hydrochloric acid was investigated by using the weight-loss method, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements. EIS results show that the transfer resistance increases with the increase of concentration of P2 and it also had an inhibiting effect on C38 steel corrosion in HCl solutions. Weight-loss essays confirm that the corrosion rate decreases as the P2 concentration increases. The inhibition efficiency for this compound studied increased with the increase in the inhibitor concentrations to attain 91.7 % at the 10^?3 M of P2. The potentiodynamic polarization curves indicated that P2 acted as a mixed-type inhibitor in hydrochloric acid.     

An investigation of carbon steel corrosion inhibition in hydrochloric acid medium by an environmentally friendly green inhibitor

The inhibition effect of polyphenols extracted from olive mill wastewater (PP) on carbon steel in 1.0 M HCl solution was studied. Inhibition efficiency of PP was carried out by using chemical (weight loss method) and electrochemical techniques [potentiodynamic polarization and electrochemical impedance spectroscopy (EIS)]. The effect of temperature and immersion time on the corrosion behavior of carbon steel in 1.0 M HCl with addition of an extract was also studied. The results show that PP acts as a very good inhibitor, and the inhibition efficiency increases with the concentration of PP and decreases with rising temperature. Polarization curves show that PP behaves as a mixed-type inhibitor in hydrochloric acid. Data, obtained from EIS measurements, were analyzed to model the corrosion inhibition process through an appropriate equivalent circuit model; a constant phase element has been used. EIS shows that charge-transfer resistance increases and the capacitance of double layer decreases with the inhibitor concentration, confirming the adsorption process mechanism. The activation energy as well as other thermodynamic parameters for the inhibition process were calculated. The adsorption of PP obeys the Langmuir adsorption isotherm.     

Multiple positive solutions of the one-dimensional p-Laplacian

In this work we investigate the existence of positive solutions of the p-Laplacian, using the quadrature method. We prove the existence of multiple solutions of the one-dimensional p-Laplacian for α?0, and determine their exact number for α=0.     

Combinatorial optimization and Green Logistics

The purpose of this paper is to introduce the area of Green Logistics and to describe some of the problems that arise in this subject which can be formulated as combinatorial optimization problems. The paper particularly considers the topics of reverse logistics, waste management and vehicle routing and scheduling.      

Volatile oils from the plant and hairy root cultures of Ageratum conyzoides L

Two lines of hairy root culture of Ageratum conyzoides L. induced by Agrobacterium rhizogenes ATCC 15834 were established under either complete darkness or 16 h light/8 h dark photoperiod conditions. The volatile oil yields from aerial parts and roots of the parent plant, the hairy root culture photoperiod line and the hairy root culture dark line were 0.2%, 0.08%, 0.03% and 0.02%, (w/w), respectively. The compositions of the volatiles from the hairy roots, plant roots and aerial parts were analysed by GC and GC-MS. The main components of the volatiles from the hairy root cultures were β-farnesene, precocene I and β-caryophyllene, in different amounts, depending on light conditions and also on the age of cultures. Precocene I, β-farnesene, precocene II and β-caryophyllene were the main constituents of the volatile oils from the parent plant roots, whereas precocene I, germacrene D, β-caryophyllene and precocene II were the main constituents of the aerial parts of the parent plant. Growth and time-course studies of volatile constituents of the two hairy root lines were compared. Qualitative and quantitative differences were found between the volatile oils from the roots of the parent plant and those from the hairy roots.     

Systèmes récursifs et algèbre de hadamard de suites récurrentes linéaires sur des anneaux commutatifs.

Abstract

Let 𝒢 be a simple finite dimensional Lie algebra over the complex numbers and let 𝒢¯ = 𝒢₁ ⊕…⊕ 𝒢 _k be a regular semisimple subalgebra of 𝒢 with each 𝒢 _i being a simple algebra of type A or C. It is shown that the lattice of submodules of a generalized Verma 𝒢-module constructed by parabolic induction starting from a simple torsion free 𝒢¯-module is almost always isomorphic to the lattice of submodules of an associated module formed as a quotient of a classical Verma module by a sum of Verma submodules. In particular, it is shown that the Mathieu admissible Verma modules involved have maximal submodules which are the sum of Verma modules.     

Uniqueness results for fractional functional differential equations with infinite delay in Fréchet spaces

In this article, a recent nonlinear alternative for contraction maps in Fréchet spaces due to Frigon and Granas [1998, Résultats de type Leray-Schauder pour des contractions sur des espaces de Fréchet, Ann. Sci. Math. Québec 22, 161–168] is used to investigate the existence and uniqueness of solutions for fractional order functional differential equations with infinite delay.