Microparticles size effects

The plot of A( )p versus log v omi for microparticles shows that, for higher scan rates, a planar diffusion-like behavior is observed. From the respective ratios with real dimensional variables, the effect ofthe microparticles size is visible (Figure 6.10). 

Tsibranska, I. Penchev, I, and Assenov. A.. The effect of microparticle-size distribution on the adsorption with biporous zeolite pellets, Chem. Eng. Sci.. 47(2), 479-483 (1992). 

Following the evaporation of water from the lipid nanodispersion applied to the skin surface, lipid particles form an adhesive layer, applying occlusion to the surface [17,40]. Therefore, the hydration of the stratum comeum may increase, which can facilitate drug penetration into deeper skin strata and even systemic availability of the drug. Occlusive effects are strongly related to particle size. Nanoparticles have turned out 15-fold more occlusive than microparticles [17], and particles smaller than 400 nm in a dispersion containing at least 35% high-crystallinity lipid proved to be most potent [41]. 

FIGURE 8.7 Effect of precipitation temperature on the size (dvn) of the resulting gelatin microparticle (lime-cured type B, bloom number 225). Bar = s.e., n = 3. (From Lou, Y. and Groves, M.J. (1995). J. Pharm. Pharmacol., 47, 97-102. With permission.)... 

Polybrominated Diphenyl Ethers. The absorption and distribution of PBDEs as a result of inhalation, ingestion, and dermal exposure are discussed in Sections 3.3.1, 3.3.2, and 3.3.3. Studies that describe the bioavailability of PBDEs from ambient air, surface water, and groundwater, or soil do not exist. Studies determining the effect of particle size and organic matter content on the bioavailability of PBDEs from soil and the role of microparticle-sorbed PBDEs on the bioavailability of PBDEs from drinking water are needed. Such studies would be useful in assessing the health effects of PBDEs on people living near hazardous waste sites. 

Figure 9.1 Effect of size on the in vitro drug release of etoposide from PLA microparticles.

Carr, K. E., Hazzard, R. A., Reid, S., and Hodges, G. M. The effect of size on uptake of orally administered latex microparticles in the small intestine and transport to mesenteric lymph nodes. Pharm. Res. 13 1205—1209, 1996. 

This is expected to happen when the mean free path (A) of the gas becomes comparable to the space between the particles ( ) of the assemblage. Since the true size of the space between the particles is not known, we assume it to be equal to the diameter of the microparticle (d ) as a first approximation. The Knudsen effect has, however, been observed at much higher pressures where d, (32]. 

A novel sizing strategy utilizes a microparticle system that enhances retention.166 A representative example is a combination of cationic potato starch (DS = 0.04), a metallosilicate hydrosol and AKD. In an approach to combine elevated filler retention, effective sizing and high paper strength, calcium carbonate is reacted with a starch-soap complex and combined with AKD.167168... 

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