Fractal geometry of normal phase clusters and magnetic flux trapping in high-Tc superconductors

The effect of geometry and morphology of superconducting structure on magnetic flux trapping is considered. It is found that the clusters of normal phase, which act as pinning centers, have significant fractal properties. The fractal dimension of the boundary of these clusters is estimated using a simple area-perimeter relation. A superconductor is treated as a percolation system. It is revealed that the fractality intensifies the magnetic flux trapping and thereby enhances the critical current value.Comment: 5 pages with 1 table and 2 figures, revtex, published in Phys.Lett.A 267 (2000) 66 with more complicated figure

Intérêt de la technique semi-directe Injection Molding dans les restaurations antérieures et mise en œuvre

The injection molding - or injection resin technique- is a recent and innovative method based upon the injection of a flowable composite, directly into the mouth and through a clear matrix. This matrix enables the transfer of a wax-up, previously prepared, thus avoiding the dentist to depend solely upon his own clinical and esthetic skills through a direct restoration. Furthermore, the progress of flowable composites with optimized mechanical and esthetical properties and the coming of guided restoration techniques contributed to the development of the Injection Molding Technique. The object of this thesis is therefore to motivate the developing of this new semi-direct technique in the anterior area, whilst explaining the details of its operating technique and its cru- cial factors and better define the key aspects of its present success and of its limiting factors.L’injection Molding ou Technique de résines composites injectées est une technique de restauration récente et innovante se basant sur l’injection de composite fluide au travers d’une gouttière transparente directement en bouche. Cette gouttière permet de transférer le wax-up préalablement confectionné afin d’éviter au praticien de se reposer uniquement sur ses habiletés cliniques et esthétiques en technique directe. Par ailleurs, l’évolution des résines composites fluides aux propriétés mécaniques et esthétiques optimisées ainsi que l’émergence de techniques de restauration guidées ont permis la mise en œuvre de l’Injection Molding. L’objet de cette thèse est donc de développer l’intérêt de cette technique semi-directe dans les secteurs antérieurs tout en expliquant sa mise en œuvre sans oublier les éléments indispensables à prendre en compte afin de mieux la cerner et de comprendre son succès actuel ainsi que ses limitations

Les dangers liés aux sports de raquettes et les conseils associés

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF

Influence of polyethylene glycol chain length on compatibility and release characteristics of ternary solid dispersions of Itraconazole in polyethylene glycol/hydroxypropylmethylcellulose 2910 E5 blends

The present study aims to elucidate the influence of the polyethylene glycol chain length on the miscibility of PEG/HPMC 2910 E5 polymer blends, the influence of polymer compatibility on the degree of molecular dispersion of itraconazole, and in vitro dissolution. PEG 2000, 6000, 10,000 and 20,000 were included in the study. Solid dispersions were prepared by spray drying and characterized with MDSC, XRPD and in vitro dissolution testing. The polymer miscibility increased with decreasing chain length due to a decrease in the Gibbs free energy of mixing. Recrystallization of itraconazole occurred as soon as a critical temperature of ca. 75 degrees C was reached for the glass transition that represents the ternary amorphous phase. Due to the lower miscibility degree between the longer PEG types and HPMC 2910 E5, the ternary amorphous phase was further separated, leading to a more rapid decrease of the ternary amorphous phase glass transition as a function of PEG and itraconazole weight percentage and hence, itraconazole recrystallization. In terms of release, an advantage of the shorter chain length PEG types (2000, 6000) over the longer chain length PEG types (10,000, 20,000) was observed for the polymer blends with 5% of PEG with respect to the binary itraconazole/HPMC 2910 E5 solid dispersion. Among the formulations with a 15/85 (w/w) PEG/HPMC 2910 E5 ratio on the other hand, there was no difference in the release profile.status: publishe