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Struvite (MgNH4PO46H2O) crystals were produced by infection associated with urea generating organ- isms.The aim of this study is to examine the interactions between the enzyme urease and two inhibitors, the first is an inhibitor monoatomic: Aluminum and the second is a polyatomic: Citrate by the methods of molecular modeling: molecular mechanics, molecular dynamics (MM+, AMBER) and molecular docking (FleX). Supersaturated solutions induce crystallization by nucleation and subsequent crystal growth .The mechanisms for the formation of calcium phosphate urinary stones are still not understood. Chemicals prod- uct has been studied extensively as inhibitors and has been observed in the attachment of crystals to in vitro study. As a complement we have using an electron microscope Hitachi TM1000, we examined specimens of crystals struvite. The various figures show a set of grains of sizes of the order of 20 µm. The majority of these particles present regular forms. This suggests the crystal growing. This result to an alteration in the expression of these faces and the development of a characteristic architectural struvite morphology. Similar changes were observed in the presence of identical concentrations of citrate acid, and Alluminuium, emphasizing the unique interaction of phosphocitrate with the struvite crystal

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International audienceThis work is a presentation of a modeling approach aimed at describing laser-matter interaction under laser-induced breakdown spectroscopy operating conditions. In order to set up a simple numerical tool to compute our model, only the most relevant processes appearing during the interaction were considered. This allowed us to develop a quick and rather accurate idea about how some physical parameters evolve during the interaction, so that the optimization of the laser beam parameters for better analytical results would be possible. For a basic understanding we used for our numerical computation a nanosecond laser pulse with an ideal Gaussian temporal profile and a pure Cu target. In order to optimize the interaction parameters, this study was focused on the effect of some of the laser parameters such as the wavelength (UV, Vis, IR), the pulse duration, and the irradiation on the results of the interaction. An investigation of the influence of some processes such as the vaporization effects and the plasma shielding was also included. The processes occuring on the material surface were closely examined as well. A comparison between the use of temperature-dependent and temperature-independent optical parameters was conducted, and their influence on the results was investigated. The use of variable optical parameters is revealed to be a means to correct the values of the temperature distribution inside the material and convert them into more realistic ones. Our code was first validated when operating under the same conditions used by other authors, and then it was used to present our proper contributions, as previously stated. (C) 2013 Optical Society of Americ