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Coating Structure (coating + structure)
Selected AbstractsAblation Resistance of Different Coating Structures for C/ZrB2,SiC Composites Under Oxyacetylene Torch FlameINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2009Houbu Li C/ZrB2,SiC composites were fabricated by polymer infiltration and pyrolysis combined with slurry impregnation method. Three kinds of coating structures for these composites were applied in order to improve their ablation resistance: pure silicon carbide coatings, ZrB2,SiC mixture coatings, and ZrC,SiC alternating multilayer coatings. The ablation experiments were carried out on an oxyacetylene torch flame with a temperature of about 3000°C. The ZrC,SiC alternating multilayer showed the best ablation resistance. The linear erosion rate for ZrC,SiC alternating multilayer coatings is half of that for ZrB2,SiC mixture and pure SiC coatings. A model was put forward to account for such a result. [source] Piroxicam/2-hydroxypropyl-,-cyclodextrin inclusion complex prepared by a new fluid-bed coating techniqueJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2009Xingwang Zhang Abstract This work was aimed at investigating the feasibility of fluid-bed coating as a new method to prepare cyclodextrin inclusion complex. The inclusion complex of the model drug piroxicam (PIX) and 2-hydroxypropyl-,-cyclodextrin (HPCD) in aqueous ethanol solution was sprayed and deposited onto the surface of the pellet substrate upon removal of the solvent. The coating process was fluent with high coating efficiency. Scanning electron microscopy revealed a coarse pellet surface, and a loosely packed coating structure. Significantly enhanced dissolution, over 90% at 5 min, was observed at stoichiometric PIX/HPCD molar ratio (1/1) and at a ratio with excessive HPCD (1/2). Differential scanning calorimetry and powder X-ray diffractometry confirmed absence of crystallinity of PIX at PIX/HPCD molar ratio of 1/1 and 1/2. Fourier transform-infrared spectrometry and Raman spectrometry revealed interaction between PIX and HPCD adding evidence on inclusion of PIX moieties into HPCD cavities. Solid-state 13C NMR spectrometry indicated possible inclusion of PIX through the pyridine ring. It is concluded that fluid-bed coating has potential to be used as a new technique to prepare cyclodextrin inclusion complex. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:665,675, 2009 [source] Very High Yield Growth of Vertically Aligned Single-Walled Carbon Nanotubes by Point-Arc Microwave Plasma CVD,CHEMICAL VAPOR DEPOSITION, Issue 3 2005F. Zhong A very high yield, selective growth of dense, vertically aligned single-walled carbon nanotubes (SWNTs) has been demonstrated for the first time on Si substrates with a sandwich-like coating structure of Al2O3/Fe/Al2O3 at a low (600,°C) temperature by point-arc microwave plasma CVD. The SWNT film thickness increases continuously with the growth time, suggesting an almost unlimited life time for the catalyst. A film thickness of 420,,m, and production yield of SWNTs to catalyst of about 770,000,% can be achieved within 2,h. [source] Analysis of coating structures and interfaces in solid oral dosage forms by three dimensional terahertz pulsed imagingJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2007J. Axel Zeitler Abstract Three dimensional terahertz pulsed imaging (TPI) was evaluated as a novel tool for the nondestructive characterization of different solid oral dosage forms. The time-domain reflection signal of coherent pulsed light in the far infrared was used to investigate film-coated tablets, sugar-coated tablets, multilayered controlled release tablets, and soft gelatin capsules. It is possible to determine the spatial and statistical distribution of coating thickness in single and multiple coated products using 3D TPI. The measurements are nondestructive even for layers buried underneath other coating structures. The internal structure of coating materials can be analyzed. As the terahertz signal penetrates up to 3 mm into the dosage form interfaces between layers in multilayered tablets can be investigated. In soft gelatin capsules it is possible to measure the thickness of the gelatin layer and to characterize the seal between the gelatin layers for quality control. TPI is a unique approach for the nondestructive characterization and quality control of solid dosage forms. The measurements are fast and fully automated with the potential for much wider application of the technique in the process analytical technology scheme. ©2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96:330,340, 2007 [source] | ||||||||||