Application of the Generalized Differential Quadrature Method in Solving Burgers'Equations

The aim of this paper is to obtain numerical solutions of the one-dimensional, two-dimensional and coupled Burgers' equations through the generalized differential quadrature method (GDQM). The polynomial-based differential quadrature (PDQ) method is employed and the obtained system of ordinary differential equations is solved via the total variation diminishing Runge-Kutta (TVD-RK) method. The numerical solutions are satisfactorily coincident with
the exact solutions. The method can compete against the methods applied in the literature.     

Determination of hydrate inhibitor in crude oil by nanoextraction-gas chromatography

This work focused on the quantitation of methanol as a hydrate inhibitor in crude oil. The novelty is nanoextraction of a polar compound from a complex non-polar matrix and selection of the proper fiber with maximum selectivity, loading percent, and lifetime. This approach not only does not require specific instrumentation, such as multiple columns and selective detectors, but also has eliminated the use of organic solvent and avoids the insertion of water inside the GC columns. The objective is optimization of extraction conditions, GC adjustments, and data processing. Experiments were conducted on the real sample of Iranian offshore crude oil by a carboxen/PDMS fiber via GC equipped with a cross-linked polyethylene glycol column and flame ionization detector. The results revealed that this fiber adsorbed the alcohols among other light non-polar compounds of crude oil. Moreover, the interference effects of ethanol were solved by proper selection of the thermal program. The LOD, LOQ, and linear range of this approach were determined to be 3.9, 12.9, and 14-229 ppm for methanol, respectively. Using the standard calibration and the standard addition methods, the relative errors of 1.6-7.2 and 5.3-14.0% were determined.     

The Anticancer Activity and HSA Binding Properties of the Structurally Related Platinum (II) Complexes

The development of resistance and unwanted harmful interaction with other biomolecules instead of DNA are the major drawbacks for application of platinum (Pt) complexes in cancer chemotherapy. To conquer these problems, much works have been done so far to discover innovative Pt complexes. The objective of the current study was to evaluate the anti cancer activities of a series of four and five-coordinated Pt(II) complexes, having deprotonated 2-phenyl pyridine (abbreviated as C^N), biphosphine moieties, i.e., dppm?=?bis(diphenylphosphino) methane (Ph₂PCH₂PPh₂) and dppa?=?bis(diphenylphosphino)amine (Ph₂PNHPPh₂), as the non-leaving carrier groups. The growth inhibitory effect of the Pt complexes [Pt(C^N)(dppm)]PF₆: C ₁ , [Pt(C^N)(dppa)]PF₆: C ₂ , and [Pt(C^N)I(dppa)]: C ₃ , toward the cancer cell lines was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. In addition, the florescence quenching experiments of the interaction between human serum albumin (HSA) and the Pt complexes were performed in order to obtain the binding parameters and to evaluate the denaturing properties of these complexes upon binding to the general carrier protein of blood stream. The structure?Cactivity relationship studies reveal that four-coordinated Pt complexes C ₁ and C ₂ with both significant hydrophobic and charge characteristics, not only exhibit strong antiproliferation activity toward the cancer cell lines, but also they display lower denaturing effect against carrier protein HSA. On the other hand, five-coordinated C ₃ complex with the unusual intermolecular NH??Pt hydrogen binding and the intrinsic ability for oligomerization, exhibits poor anticancer activity and strong denaturing property. The current study reveals that the balance between charge and hydrophobicity of the Pt complexes, also their hydrogen binding abilities and coordination mode are important for their anticancer activities. Moreover, this study may suggest C ₁ and C ₂ as the potential template structures for synthesis of new generation of four-coordinated Pt complexes with strong anticancer activities and weak denaturing effects against proteins.     

Application of nano-baskets in preconcentration of tetrahedral oxoanions in the produced water of oil wells

This paper introduces a supramolecular-based microextraction technique and examines its ability in preconcentration of tetrahedral oxoanions in the produced water. Diacid p-tert-butylcalix[4]arene in the cone conformation was synthesised and used. The respective parameters including ligand concentration, volume of aqueous disperser, salt effect and extraction time were optimised. The linear range, detection limit (S/N = 3) and precision (relative standard deviation, n = 6) were determined to be in the range of 1.0–280, 2.0–42.0 μg/l and 2.6–11.0%, respectively.     

Numerical solution of the Schrödinger equations by using Delta-shaped basis functions

Numerical simulations of the nonlinear Schrödinger equations are studied using Delta-shaped basis functions, which recently proposed by Reutskiy. Propagation of a soliton, interaction of two solitons, birth of standing and mobile solitons and bound state solutions are simulated. Some conserved quantities are computed numerically for all cases. Then we extend application of the method to solve some coupled nonlinear Schrödinger equations. Obtained systems of ordinary differential equations are solved via the fourth- order Runge–Kutta method. Numerical solutions coincide with the exact solutions in desired machine precision and invariant quantities are conserved sensibly. Some comparisons with the methods applied in the literature are carried out.     

Cyclicity of laryngeal cavity resonance due to vocal fold vibration

Acoustic effects of the time-varying glottal area due to vocal fold vibration on the laryngeal cavity resonance were investigated based on vocal tract area functions and acoustic analysis. The laryngeal cavity consists of the vestibular and ventricular parts of the larynx, and gives rise to a regional acoustic resonance within the vocal tract, with this resonance imparting an extra formant to the vocal tract resonance pattern. Vocal tract transfer functions of the five Japanese vowels uttered by three male subjects were calculated under open- and closed-glottis conditions. The results revealed that the resonance appears at the frequency region from 3.0 to 3.7 kHz when the glottis is closed and disappears when it is open. Real spectra estimated from open- and closed-glottis periods of vowel sounds also showed the on-off pattern of the resonance within a pitch period. Furthermore, a time-domain acoustic analysis of vowels indicated that the resonance component could be observed as a pitch-synchronized rise-and-fall pattern of the bandpass amplitude. The cyclic nature of the resonance can be explained as the laryngeal cavity acting as a closed tube that generates the resonance during a closed-glottis period, but damps the resonance off during an open-glottis period.     

2, 4, 6-Trichloro-1, 3, 5-triazine/dimethylformamide as an efficient reagent for one-pot conversion of alcohols into N-alkylphthalimides

<正>An efficient and mild method for the direct conversion of alcohols into N-alkylphthalimides using 2,4,6-trichloro-1,3,5-triazine and dimethylformamide was described.The reaction was preceded via(alcoxymethylene) dimethylammonium chloride intermediate and produced corresponding N-alkylphthalimides in good-to-excellent yields.     

A two grid algorithm based on perturbation and homotopy methods

In this paper, we propose a new class of bi-grid algorithm to solve large scale linear algebraic equations. This method is based on homotopy, perturbation technique and Padé approximants. To cite this article: R. El Mokhtari et al., C. R. Mecanique 330 (2002) 825–830.