Search

Multivariate data analysis was applied to confocal Raman measurements on stents coated with the polymers and drug used in the CYPHER Sirolimus-eluting Coronary Stents. Partial least-squares (PLS) regression was used to establish three independent calibration curves for the coating constituents: sirolimus, poly(n-butyl methacrylate) [PBMA], and poly(ethylene-co-vinyl acetate) [PEVA]. The PLS calibrations were based on average spectra generated from each spatial location profiled. The PLS models were tested on six unknown stent samples to assess accuracy and precision. The wt % difference between PLS predictions and laboratory assay values for sirolimus was less than 1 wt % for the composite of the six unknowns, while the polymer models were estimated to be less than 0.5 wt % difference for the combined samples. The linearity and specificity of the three PLS models were also demonstrated with the three PLS models. In contrast to earlier univariate models, the PLS models achieved mass balance with better accuracy. This analysis was extended to evaluate the spatial distribution of the three constituents. Quantitative bitmap images of drug-eluting stent coatings are presented for the first time to assess the local distribution of components.

A novel multigrid algorithm is presented for the fast evolution of level-set-based geometric active contours and is compared it with other established numerical schemes. The combined algorithm has allowed the rapid evolution of the contour and convergence to its final configuration after very little iteration and the image segmentation experiments have demonstrated the efficiency and accuracy of the method.

Amidine, amidrazone and amidoxime derivatives were prepared for the powerful glycosidase inhibitors, D-gluco, D-mannono, and D-galactonolactams. All derivatives of the D-gluco series powerfully inhibit sweet almond beta-glucosidase and react with mannose- and galactose-processing enzymes. The latter two derivatives of the D-manno series powerfully inhibit jackbean alpha-mannosidase, mung bean alpha-mannosidase and fungal beta-mannosidase.

The results from the combined experimental and theoretical study of adhesion between hard and soft layers that are relevant to medical devices such as drug-eluting stents and semiconductor applications are presented. The comparison results from the measured and predicted interfacial fracture energies provide insight into the overall fracture energies and combination of adhesion theories and fracture mechanics concepts.