IN VITRO EFFECT OF ACETYLSALICYLIC ACID ON CALCIUM OXALATE CRYSTALLIZATION: AN APPROACH TO ANTILITHIASIS

Objective: In recent years, significant progress has been made in identifying and counting physico-chemical processes involved in urinary stone formation. The ability of urine to inhibit calcium oxalate crystallization is considered an important mechanism against stone formation. Several natural substances were tested to inhibit calcium oxalate crystallization. In the present study, we evaluate the effects of acetylsalicylic acid, also known as Aspirin, as an inhibitor of calcium oxalate crystallization in vitro.Methods: The nucleation and aggregation of calcium oxalate crystals were studied using turbidimetric 400-sec time course measurements of optic density at 620 nm after mixing solutions containing calcium chloride and sodium oxalate at room temperature, pH 5.7. The formation of crystals is induced by the addition of the oxalate to calcium solution. The effects on calcium oxalate crystal growth of acetylsalicylic acid with various concentrations were examined. The maximum increase of optic density in the course of time reflects maximum rate of formation of new particles. After reaching equilibrium, a progressive decrease of optic density with time is observed. Rate of aggregation is derived from the maximum decrease in optic density.Results: The results showed that if a concentration of acetylsalicylic acid is more than 1,66 mM both rate of formations of new particles and Rate of aggregation decreased (P<0.05).Conclusion: acetylsalicylic acid has a significant effect on nucleation as well as on crystal growth stage; consequently, it inhibits the crystal formation of calcium oxalate urinary lithiasis. Â

Optical and photovoltaic properties of indium selenide thin films prepared by van der Waals epitaxy

Indium selenide thin films have been grown on p-type gallium selenide single crystal substrates by van der Waals epitaxy. The use of two crucibles in the growth process has resulted in indium selenide films with physical properties closer to these of bulk indium selenide than those prepared by other techniques. The optical properties of the films have been studied by electroabsorption measurements. The band gap and its temperature dependence are very close to those of indium selenide single crystals. The width of the fundamental transition, even if larger than that of the pure single crystal material, decreases monotonously with temperature. Exciton peaks are not observed even at low temperature, which reveals that these layers still contain a large defect concentration. The current–voltage characteristic of indium selenide thin film devices was measured under simulated AM2 conditions. The solar conversion efficiency of these devices is lower than 0.6%. The high concentration of defects reduces the diffusion length of minority carriers down to values round to 0.2 μ[email protected] ; [email protected]

Trois méthodes pratiques pour le dosage des espèces arséniées d'intérêt toxicologique : application à un cas d'intoxication mortelle par l'anhydride arsénieux

Cet article décrit les méthodes de dosage et de spéciation de l'arsenic, mises au point par les auteurs dans le cadre de leurs travaux de recherche sur le dosage des espèces arséniées d'intérêt toxicologique - arsenic minéral, sous forme arsénite [As(III)] et arséniate [As(V)] et ses metabolites [acide monométhylarsonique (MMA) et acide diméthylarsinique (DMA)] dans les milieux biologiques. Trois méthodes analytiques sont décrites. Ce sont des méthodes simples, rapides, sélectives et sensibles. Elles permettent de différencier et de quantifier les espèces arséniées dans les différents milieux biologiques. Chaque méthode est destinée à une analyse donnée : - La première, appelée méthode Astox est destinée au dosage de l'arsenic total d'intérêt toxicologique - La deuxième, dite méthode As(III) permet de doser sélectivement As( III) - La troisième, appelée méthode As spéciation permet une analyse fine par chromatographie liquide haute performance (CLHP). - La méthode As spéciation a été appliquée à la spéciation de l'arsenic dans les tissus humains suite à une intoxication mortelle par l'anhydride arsénieux. Cette étude est à notre connaissance la première à avoir évalué la distribution des espèces arséniées dans les tissus humains

Thin film bismuth(III) sulfide/zinc sulfide composites deposited by spray pyrolysis

(Bi2S3)(x)(ZnS)(1-x) composites in thin films were successfully grown on glass substrates by the spray pyrolysis technique. The films growth were prepared by the reaction of aqueous solutions of bismuth(III) chloride (BiCl3) and zinc chloride (ZnCl) with Thiourea on substrates heated to a temperature of 280 °C. The structural properties have been identified using X-ray diffraction spectra. The deposited films are of polycrystalline natures. The both of the two phases mixed (Bi2S3 and ZnS) were well observed in the X-ray diffraction plots. The optical properties were also studied using transmittance and reflectance measurements in the wavelength range (200–2500 nm). Optical gaps were evaluated; we are found that (Bi2S3)(x)(ZnS)(1-x) (x = 0–1) composites in thin films are characterized by two optical gaps limited between the gap of Bi2S3 and that of ZnS films in the pure phase. Keywords: Thin films, (Bi2S3)(x)(ZnS)(1-x), Composite materials, Structural and optical propertie

An epidemiological study on the composition of urinary stones in Morocco in relation to age and sex

Objective: To study the composition of urinary stones, evaluate the percentage of each stone type and assess the association between the stone type and the sex and age in Moroccan stone formers. Subjects and methods: This epidemiologic study of urolithiasis was carried out in the Rabat-Salé region (Morocco) between 2008 and 2013. A series of 828 urinary stones from 537 men and 265 women was analyzed using Fourier transform infrared spectroscopy in order to evaluate the percentage of each stone type. The results were compared to the patients’ demographic data in order to assess the association between the stone type and the sex and age. Results: The overall sex ratio (male/female) was 2.03:1, and the majority of patients were aged between 40 and 60. The majority of stones were composed of calcium oxalate (66.6%), followed by anhydrous uric acid (18.1%), carbapatite (7.9%), struvite (4.4%) and cystine (0.6%). Anhydrous uric acid stones in this study accounted for a relatively higher rate in males and females compared to that reported in other studies. Our results also showed a higher percentage of carbapatite stones in females compared to males and an increase of the prevalence of anhydrous uric acid stones with age. In addition, the percentage of calcium oxalate stones decreased, while that of carbapatite stones increased with age

Site location of Al-dopant in ZnO lattice by exploiting the structural and optical characterisation of ZnO:Al thin films

The zinc oxide thin films, highly transparent, doped aluminium were prepared on glass substrates by the reactive chemical spray method. The incorporation nature of Al atoms in the ZnO lattice was determined by X-ray diffraction and optical analyses. Indeed, for low doping ⩽2%, the results of X-ray spectra analysis show a simultaneous reduction of lattice parameters (a and c), this variation, which follows VEGARD’s law, tends to indicate a substitution of Zn by Al. By against for doping >2% the increase in the lattice parameters thus the grain sizes, in accordance with the VEGARD’s law can be explained by occupation of the interstitial sites by Al atoms. Beyond 4%, the material tends to get disorderly and the crystallites orientation is random. The studied optical properties show that the variation of the optical gap follows a law of the x3/2 form for x < 3% (x is the aluminium atom fraction incorporated in the ZnO lattice). The granular structure is fairly visible and some local growths are disrupted. The crystallite size at low enlargement is coherent with the XRD results. Keywords: Al-doped ZnO thin films, XRD, Substitutional and interstitial sites, Band gap, SE