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Precipitation Inhibitors (precipitation + inhibitor)
Selected AbstractsRadial basis function Hermite collocation approach for the numerical simulation of the effect of precipitation inhibitor on the crystallization process of an over-saturated solutionNUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 2 2006A. Hernandez Rosales Abstract This work is concerned with the analysis of the effect of precipitation inhibitors on the growth of crystals from over-saturated solutions, by the numerical simulation of the fundamental mechanisms of such crystallization process. The complete crystallization process in the presence of precipitation inhibitor is defined by a set of coupled partial differential equations that needs to be solved in a recursive manner, due to the inhibitor modification of the molar flux of the mineral at the crystal interface. This set of governing equations needs to satisfy the corresponding initial and boundary conditions of the problem where it is necessary to consider the additional unknown of a moving interface, i.e., the growing crystal surface. For the numerical solution of the proposed problem, we used a truly meshless numerical scheme based upon Hermite interpolation property of the radial basis functions. The use of a Hermitian meshless collocation numerical approach was selected in this work due to its flexibility on dealing with moving boundary problems and their high accuracy on predicting surface fluxes, which is a crucial part of the diffusion controlled crystallization process considered here. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006 [source] In Vitro Formation of Nanocrystalline Carbonate Apatite , A Structural and Morphological Analogue of Atherosclerotic PlaquesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 26 2007Lars-Fride Olsson Abstract The in vitro formation of carbonate apatite in solutions with ion concentrations comparable to those in human serum was studied. The composition and morphology of the resulting apatite precipitate displayed a hierarchical assembly of elongated plate-shaped nanocrystals of carbonate apatite analogous to previously characterized bioapatites formed in vivo. The main conclusion is that so-called bioapatites may form in vitro and that precipitation inhibitors most likely are essential for the prevention of spontaneous calcification at normal human serum ion concentrations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Combined use of crystalline salt forms and precipitation inhibitors to improve oral absorption of celecoxib from solid oral formulationsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2007Héctor R. Guzmán Abstract Biopharmaceutical evaluation of crystalline celecoxib salts in novel solid formulations, which were designed to simultaneously facilitate dissolution and inhibit precipitation in vitro, showed fast and complete absorption in beagle dogs at doses up to 7.5 mg/kg orally. In contrast, 5 mg/kg celecoxib in the form of Celebrex® showed approximately 40% absolute bioavailability in a cross-over experiment. An in vitro,in vivo correlation was observed in dog, and a threshold level of in vitro dissolution needed to maximize in vivo performance was highlighted. Oral bioavailability was limited in the absence of excipient combinations that delayed precipitation of celecoxib free acid as the salt neutralized in the GI fluid. Formulations of crystal forms having high energy (a ,spring'), thus transiently increasing solubility in aqueous solution relative to the free acid, combined with excipients functioning as precipitation inhibitors (,parachutes') were shown to provide both enhanced dissolution and high oral bioavailability. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 2686,2702, 2007 [source] Thermodynamic micellization model for asphaltene precipitation inhibitionAICHE JOURNAL, Issue 2 2000Huanquan Pan Aromatic solvents and oil-soluble amphiphiles are recognized as asphaltene precipitation inhibitors in oil production and transportation. In the absence of the model describing the effect of these inhibitors on asphaltene precipitation from crudes, proposed is a thermodynamic micellization model explaining the inhibition mechanism for both aromatic solvents and oil-soluble amphiphiles. The model shows that aromatic solvents are concentrated in the micellar shell, and the interfacial tension between the asphaltene micellar core and shell is reduced as the micelles becomes stabler. A crude, mixed with a small amount of an oil-soluble amphiphile, achieves a high micellar stability. The amphiphiles behave like resin species of the crude and coadsorb onto the micellar core with resins. The adsorption enthalpy of an amphiphile onto the micellar core is much higher than that of the resin and, therefore, amphiphiles can be very effective inhibitors. The results suggest that the adsorption enthalpy data can be used to screen the amphiphiles for asphaltene precipitation inhibition. For a given oil-soluble amphiphile, this model can predict the amount of the amphiphile required to inhibit the precipitation. [source] Radial basis function Hermite collocation approach for the numerical simulation of the effect of precipitation inhibitor on the crystallization process of an over-saturated solutionNUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 2 2006A. Hernandez Rosales Abstract This work is concerned with the analysis of the effect of precipitation inhibitors on the growth of crystals from over-saturated solutions, by the numerical simulation of the fundamental mechanisms of such crystallization process. The complete crystallization process in the presence of precipitation inhibitor is defined by a set of coupled partial differential equations that needs to be solved in a recursive manner, due to the inhibitor modification of the molar flux of the mineral at the crystal interface. This set of governing equations needs to satisfy the corresponding initial and boundary conditions of the problem where it is necessary to consider the additional unknown of a moving interface, i.e., the growing crystal surface. For the numerical solution of the proposed problem, we used a truly meshless numerical scheme based upon Hermite interpolation property of the radial basis functions. The use of a Hermitian meshless collocation numerical approach was selected in this work due to its flexibility on dealing with moving boundary problems and their high accuracy on predicting surface fluxes, which is a crucial part of the diffusion controlled crystallization process considered here. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006 [source] | ||||||||||