Aqueous HPMCAS coatings: Effects of formulation and processing parameters on drug release and mass transport mechanisms

2006 ◽  
Vol 63 (3) ◽  
pp. 262-269 ◽  
Author(s):  
Florence Siepmann ◽  
Juergen Siepmann ◽  
Mathias Walther ◽  
Ross MacRae ◽  
Roland Bodmeier
Keyword(s):  
Drug Release ◽  
Mass Transport ◽  
Processing Parameters ◽  
Transport Mechanisms ◽  
Mass Transport Mechanisms

Drug release from lipid-based implants: Elucidation of the underlying mass transport mechanisms

2006 ◽  
Vol 314 (2) ◽  
pp. 137-144 ◽  
Author(s):  
C. Guse ◽  
S. Koennings ◽  
F. Kreye ◽  
F. Siepmann ◽  
A. Goepferich ◽  
...  
Keyword(s):  
Drug Release ◽  
Mass Transport ◽  
Transport Mechanisms ◽  
Mass Transport Mechanisms

scholarly journals Temperature Effects on the Crystallization and Coarsening of Nano-CeO2 Powders

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
H. F. Lopez ◽  
H. Mendoza
Keyword(s):  
Activation Energy ◽  
Mass Transport ◽  
Ostwald Ripening ◽  
Effect Of Temperature ◽  
Transport Mechanisms ◽  
X Ray Diffraction ◽  
Measured Activation Energy ◽  
Measured Activation ◽  
Mass Transport Mechanisms ◽  
Nanoparticle Sizes

The effect of temperature on nano-CeO2 particle coarsening is investigated. The nanoceria powders were synthesized using the microemulsion method and then exposed to temperatures in the range of 373–1273 K. It was found that the nanoparticles exhibited a strong tendency to form agglomerates and through the application of ultrasound these agglomerates could be broken into smaller sizes. In addition average nanoparticle sizes were determined by powder X-ray diffraction (XRD). The outcome of this work indicates that the initial nano-CeO2 powders are amorphous in nature. Annealing promotes CeO2 crystallization and a slight shift in the (111) XRD intensity peaks corresponding to CeO2. Moreover, at temperatures below 773 K, grain growth in nano-CeO2 particles is rather slow. Apparently, mass transport through diffusional processes is not likely to occur as indicated by an estimated activation energy of 20 kJ/mol. At temperatures above 873 K, the measured activation energy shifted to 105 kJ/mol suggesting a possible transition to Ostwald-Ripening type mass transport mechanisms.

Sign in / Sign up

Export Citation Format

Share Document