Dissolution of solid particles in liquids

<p>Sustained delivery of a camptothecin prodrug – CZ48 by nanosuspensions with improved pharmacokinetics and enhanced anticancer activity</p>

“…In contrast, nanosuspensions contain solid drug particles of nanometer sizes, and the drug molecules need to be dissolved into the diffusion layer first and then into the bulk medium before being released from the dialysis bag. 35 The slow dissolving process contributes to the slower and sustainedrelease profiles of CZ48 from nanosuspensions. The mean values of initial rate of nanosuspensions of various sizes increased as the particle size decreased, which is consistent with the previous work in our laboratory by Qi.…”

“…40 The pattern of high drug distributions in liver and spleen from nanosuspensions is very similar to that of liposome and other nanoparticle formulations. 35,[41][42][43] Following the uptake, the RES acts as a depot and drug can be released slowly back to the systemic circulation, which may contribute to the sustained plasma drug level achieved from nanosuspensions. 17 CZ48 exerts the antitumor activity by CE-mediated hydrolysis to the active metabolite CPT invivo.…”

CO2 Capture Modeling Using Heat-Activated Serpentinite Slurries

“…The model incorporates protonic activity dependency because a protonic mechanism is most significant in our experimental system. , Nevertheless, the roles of bicarbonate and carbonate species have been implicated directly in increasing silicate dissolution rates in the neutral and basic pH range, − and the bicarbonate (ligand) mechanism has also been shown to exhibit some influence at pH values of ≥7 for serpentinite. , Similar trends have been observed in the dissolution of brucite. , The surface complexation model (SCM) developed by Pokrovsky and Schott for forsterite (a magnesium silicate similar in many respects to heat-activated serpentinite) accounted for the observed 0.5 order dependence of the dissolution rate upon proton activity, which was also demonstrated by Rosso and Rimstidt and others, − as well as for serpentinite. , We adopt a 0.5 reaction order dependency to protonic activity for the forward rate of the mineral dissolution reaction (eq ), consistent with various experimental studies and postulated mechanisms for silicates and oxides/hydroxides. The similarity in protonic dependency for these different minerals reflects the commonality of the hypothesized dissolution mechanisms. − We also include the reverse dissolution reaction because the inhibition of silicate dissolution rates by Mg 2+ ions leached into solution has been evident in our work and that of others. ,,, This effect recognizes the finite size of the bulk liquid phase and the effect of the dissolved solute on the bulk liquid concentration where k fs is the forward rate constant (mol m –2 s –1 ) related to the solid surface area (m 2 L –1 ) (on the basis of the laser diffraction method), [H] is the protonic activity (mol L –1 ) treated as unitless, [Mg] is the activity of Mg 2+ (mol L –1 ) treated as unitless, S s is the physical reactive surface area of the solid (m 2 L –1 ) based on the laser diffraction method, and k bs is the backward rate constant (mol m –2 s –1 ) ( k fs / K diss ), where K diss is the solubility product for the reactive amorphous Mg phase (1 × 10 +16 ) (unitless) and where k sfs is the specific or intrinsic rate constant (mol m –2 s –1 ), Mg­(OH) 2 is the concentration of Mg­(OH) 2 solid (as proxy for the reactive amorphous Mg phase) at any given point in time (mol L –1 ), and Mg­(OH) 2 ini is the initial concentration of Mg­(OH) 2 solid (as proxy for the reactive amorphous Mg phase) (mol L –1 ).…”

Nonisothermal dissolution and crystallization of ellipsoidal particles in liquid solutions

“…2 In summary, the crystallization/dissolution of solid particles in liquid solutions is analyzed theoretically. In particular, the effect of the heat of crystallization/dissolution on the kinetic behavior of the phenomena under consideration is taken into account.…”

“…The first of these assumes that the movement of the solid surface due to dissolution/ crystallization is slow compared to the rate of diffusion of solute molecules. [1][2][3] In this case, a moving-boundary problem can be approximated by a fixed-boundary one, which simplifies significantly the subsequent mathematical treatment. In a study of the isothermal growth of a spherical crystal in an infinite and stagnant solution, Wey and Estrin 4 derived an approximate expression for the temporal variation in crystal size.…”