Transport phenomena delivery

Recently [16] we have shown that water diffusion in the PHB films with 100 pm thick was completed in several tens of minutes, whereupon the films absorbed the limiting equilibrium concentration of water (ca. 1 wt %). Structural relaxation in PHB under humid conditions is finished in longer period of time (nearly 1000 minutes). We have investigated kinetics of release for several tens of days, therefore, to a first approximation, a water transport phenomenon in PHB is not essential. However, long-term kinetics of drug release from PHB films has an intricate form and demands special analysis for both diffusion modeling and drug delivery application. 

Economists frequently argue that congestion is a transport-sector internal phenomenon imposed by transport users on each other. Impacts on the economy, e.g., commuters arriving late at their workplace or goods deliveries being delayed are well known by the travellers or shippers and thus congestion- or delay-related time costs may be computed, but must not be added up with system-external costs. Moreover,... 

Electroosmosis is the bulk fluid flow that occurs when a voltage gradient is imposed across a charged membrane. Transport by convection allows the delivery and extraction of neutral and zwitterionic compounds and plays a major role in the movement of large, poorly mobile cations. Electroosmosis is an electrokinetic phenomenon, which may be described by nonequilibrium thermodynamics [24] ... 

Weaver JC. Electroporation A general phenomenon for manipulating cells and tissues. J. Cell Biochem. 1993 51(4) 426-435. Prausnitz MR. A practical assessment of transdermal drug delivery by skin electroporation. Adv. Drug Deliv. Rev. 1999 35 61-76. Edwards DA, Prausnitz MR, Danger R, and Weaver JC. Analysis of enhanced transdermal transport by skin electroporation. J. Control. Rel. 1995 34 211-221. 

Diffusion is one of the basic mass transport mechanisms, which is involved in the control of drag release from numerous drag delivery systems (14-16). Pick was the first to treat this phenomenon in a quantitative way (21), and the textbook of Crank (22) provides various solutions of Pick s second law for different device geometries and initial and boundary conditions. A very interesting introduction into this type of mass transport is given by Cussler (23). 

Q phases are already one of the most promising, research-intensive LLC-based drug delivery systems because of the superior diffusion and access characteristics afforded by their 3-D interconnected nanopore systems [129, 151-154]. Initial results have also shown that Q-phase LLC materials also possess superior transport and access properties in membrane applications compared to L and Hu phases [170]. This phenomenon could translate into the design of superior LLC-based heterogeneous catalysts or bulk sorbents, as the interconnected nanochannels may provide more open pathways for better accessibility and selective molecular and/or ion diffusion. However, designing functional amphiphiles that can readily form useful Q-phase materials is not a straightforward task. To date, less than a handful of LLC monomers are known in the literature that can be polymerized in Q phases [172-175]. 

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