Electrohydrodynamic peristaltic flow of a viscoelastic Oldroyd fluid with a mild stenosis: Application of an endoscope

The effect of a vertical alternating current, electric field, and heat transfer on a peristaltic flow of a dielectric viscoelastic Oldroyd fluid is studied. This analysis involves uniform and nonuniform annuli having a mild stenosis. The analytical solutions of equations of motion are based on the perturbation technique. This technique depends on two parameters: amplitude ratio and small wave number. Numerical calculations are performed to obtain the effects of several parameters, such as the electrical Rayleigh number, temperature gradient, Reynolds number, wave number, maximum height of stenosis, and Weissenberg numbers, on the distributions of velocity, temperature, electric potential, and wall shear stress. It is found that the above-mentioned distributions in the case of a convergent tapered tube are larger than those in the case of a non-tapered one as well as a diverging tapered tube.     

Photo-physical and structural interactions between viologen phosphorus-based dendrimers and human serum albumin

This work deals with photo-physical and structural interactions between viologen phosphorus dendrimers and human serum albumin (HSA). Viologens are derivatives of 4,4′-bipyridinium salts. Aiming to rationalize the parameters governing such interactions eight types of these polycationic dendrimers in which the generation, the number of charges, the nature of the core and of the terminal groups vary from one to another, were designed and used. The influence of viologen-based dendrimers' on human serum albumin has been investigated. The photo-physical interactions of the two systems have been monitored by fluorescence quenching of free l-tryptophan and of HSA tryptophan residue. Additionally, using circular dichroism (CD) the effect of dendrimers on the secondary structure of albumin was measured. The obtained results show that viologen dendrimers interact with human serum albumin quenching its fluorescence either by collisional (dynamic) way or by forming complexes in a ground state (static quenching). In some cases the quenching is accompanied by changes of the secondary structure of HSA.     

A method for the evaluation of design limits for structural materials in a cyclic state of creep

The purpose of the present paper is to demonstrate how the minimum theorems proposed in an accompanying paper (Ponter and Boulbibane, 2002) can be utilised in the prediction of the deformation and life assessment of structures subjected to cyclic mechanical and thermal loadings. The developed method, which is based upon bounding theorems and an associate programming method, the Linear Matching method, takes into account the changes in residual stress field occurring within a cycle. Although the solution provided a bound on the inelastic work, it also appears that generally the displacements predicted by this solution are smaller than those that would be predicted by the rapid cycle solution. By way of illustration a simple non-linear viscous model is adopted and a number of solutions are presented involving a Bree plate problem subjected to cyclic histories of load and temperature. An elastic follow-up factor is identified as a key design parameter for high temperature dwell periods.     

New and efficient synthesis of bi- and trisubstituted indazoles

In this paper, the synthesis of bi- and trisubstituted indazoles was described. 4-Alkoxy-7-aminoprotected-indazole or 7-aminoprotected-indazole derivatives were prepared selectively using SnCl₂ in alcohol or SnCl₂ in ethyl acetate, respectively. The effects of the halogen atom in position 3 and of the N-alkylation in N-1 position of 7-nitroindazoles were investigated.     

Novel pyrazoline and pyrazole porphyrin derivatives: synthesis and photophysical properties

2-Vinyl-5,10,15,20-tetraphenylporphyrinatozinc(II) reacts with nitrile imines, generated in situ from ethyl hydrazono-α-bromoglyoxylates, affording the corresponding pyrazolines in good to excellent yields. Treatment of pyrazoline derivatives with DDQ affords the corresponding pyrazole derivatives with moderate to excellent yields. When the hydrolysis of ester group in the pyrazoline derivatives was considered, it was observed the concomitant oxidation of the heterocyclic unit, which allowed directly obtaining porphyrin-pyrazole derivatives with a carboxylic group, in very good yields.The photophysical properties of the pyrazoline and pyrazole porphyrin derivatives show that the influence of the heterocyclic substituents is limited by the tendency of these molecules to aggregate. All other properties and especially the triplet kinetics remain unaffected. The adducts with low tendency to aggregate showed very high singlet oxygen yield, which makes these compounds interesting for their use as photosensitizers for PDT.     

Synthesis of Novel Substituted Indazoles via Nucleophilic Substitution of Hydrogen (SNH)

New four‐substituted indazoles 4a–e were synthesized by regioselective nucleophilic substitution of hydrogen of N‐alkyl‐7‐nitroindazoles 2a,b with arylacetonitriles 3a–c . Compounds 4a–e were reacted with arylsulfonyl chloride in pyridine to give some new indazole linked sulfonamides with good yields. The S_NH at position C‐4 of 7‐nitroindazole with arylacetonitrile is confirmed by X‐ray diffraction analysis of compounds 4e and 6a .     

A Liquid Membrane-Based Green Method for the Separation and Determination of Lead in Saline Waters

In this work, the authors proposed a new liquid membrane-based method for the determination of lead in saline waters. In this case, the new method is based on lead quantification by inductively coupled plasma-mass spectrometry (ICP-MS) after a preconcentration step by means of a bulk liquid membrane (BLM) system. With no sample manipulation, the system transports and preconcentrates the analyte ions in the sample into the acidic receiving solution, by means of an organic membrane containing di-(2-ethylhexyl)-phosphoric acid (DEHPA) acting as a chemical carrier. The chemical variables controlling Pb²⁺ permeation through the membrane were studied by use of a modified simplex approach. The most appropriate preconcentration rates were found at sample pH 4.7, maintained with a 0.08-M acetate buffer solution, a 0.07-M DEHPA concentration, and a 0.23-M HNO₃ receiving solution. Under these conditions, an extraction yield of 93.8 ± 0.1% and a preconcentration factor of 4.2 were obtained, thus allowing lead selective separation and accurate determination in real samples at environmental concentration levels. The system was tested with several real samples from the Gulf of Cádiz containing lead at the low ppb levels.     

The investigation of magnetic state variations in α-Fe and its alloys by means of continuous temperature scanning of the Mössbauer effect

A new method for continuous temperature scanning of the Mössbauer effect was developed permitting the measurement in a broad temperature range with satisfactory precision. The temperature dependence of Mössbauer radiation transmission for -Fe, amorphous Fe-P and for alloys was measured from 20–800°C. A region of anomalous transmission was observed for crystalline -Fe and its alloys and a new method of Debye-temperature determination was proposed.     

Valorization of Moroccan Bentonite Deposits: “Purification and Treatment of Margin by the Adsorption Process”

The main objective of this work was to contribute to the reduction in the contamination of phenolic compounds contained in margin by an adsorption process on two types of raw bentonite. The margin used in the studies was collected from a semi-modern oil mill located in the Nador–Morocco region. The results of the physico-chemical analyses showed that the effluents of the oil mills showed that they are highly polluted, particularly in terms of the total suspended solids (TSS), chemical oxygen demand (COD), and iron content of around 154.82 (mg/L), and copper content of 31.72 (mg/L). The mineralogy of bentonites studied by X-ray diffraction (XRD) reveals the existence of two types of montmorillonite; theoretically, the diffraction peak (001) of the montmorillonite appears at 15 Å, with a basal spacing that corresponds to a calcium pole, and the diffraction peak (001) appears at 12Å, with a basal spacing that corresponds to a sodium pole. The specific surface area of the bentonite used is characterized by a large specific surface area, varying between 127.62 m²·g⁻¹ and 693.04 m²·g⁻¹, which is due to the presence of hydrated interleaved cations. This surface is likely to increase in aqueous solution depending on the solid/liquid ratio that modulates the degree of hydration. With a high cation exchange capacity (CEC) (146.54 meq/100 g), samples of margin mixed with raw bentonites at different percentages vary between 5% and 100%. The potential of Moroccan bentonite for the phenol adsorption of 9.17 (g/L) from aqueous solutions was investigated. Adsorption tests have confirmed the effectiveness of these natural minerals in reducing phenolic compounds ranging from 8.72% to 76.23% contained in the margin and the efficiency of heavy metal retention through microelements on raw bentonites. The very encouraging results obtained in this work could aid in the application of adsorption for the treatment of margin.