Afshin Falsafi | University of Minnesota (original) (raw)

Papers by Afshin Falsafi

A (e.g. hardenable dental) composition is described comprising (e.g. a first part comprising) an ... more A (e.g. hardenable dental) composition is described comprising (e.g. a first part comprising) an encapsulated material wherein the encapsulated material comprises a basic core material and an inorganic shell material comprising a metal oxide surrounding the core; and (e.g. a second part comprising) water or an acidic component. Also described is an encapsulated material (e.g. suitable for use in a biological carrier material) comprising a basic core material and an inorganic shell material comprising a metal oxide surrounding the core.

L'invention concerne des procedes d'utilisation d'une composition dentaire ayant une ... more L'invention concerne des procedes d'utilisation d'une composition dentaire ayant une teinte photoblanchissable et un composant acide avec un pKa inferieur a 4,5. La teinte photoblanchissable est choisie dans le groupe consistant en les teintes aminoanthraquinone, les teintes azoiques et les combinaisons de celles-ci. La couleur vieillie de la composition dentaire est sensiblement la meme que la couleur de la composition dentaire immediatement apres durcissement.

L'invention concerne des agents d'addition-fragmentation ayant les groupes fonctionnels s... more L'invention concerne des agents d'addition-fragmentation ayant les groupes fonctionnels suivants : 1) un groupe d'addition-fragmentation labile qui peut se cliver et se reformer pour soulager les contraintes, 2) au moins un groupe a haut indice de refraction, et 3) au moins un groupe polymerisable ethyleniquement insature.

Proquest Dissertations and Theses Thesis University of Minnesota 1998 Publication Number Aai9913340 Isbn 9780599118614 Source Dissertation Abstracts International Volume 59 11 Section B Page 5960 182 P, Dec 1, 1998

The immediate goals of this thesis were to make a significant advance in measuring adhesion in th... more The immediate goals of this thesis were to make a significant advance in measuring adhesion in the presence of viscoelastic effects and to understand the relation of structure and surface architecture to adhesion in polymeric systems. Contact mechanics was used as a tool to measure interfacial properties. In this methodology based on the Johnson-Kendall-Roberts (JKR) theory of adhesive contact, two solids of revolution (generally hemispheres) are pressed against each other. The force and contact area are monitored as steps of compression are imposed; the higher the adhesion, the larger the contact area and the lower the force under a given compression. The main feature of this technique is its direct manner of characterization: the surfaces of interest are brought into contact directly. As an integral part of this thesis, an automated apparatus was designed and built to ensure high precision in metrology and good control over experimental conditions. The contact mechanical analysis has originally been developed for elastic materials. The first attempt of this thesis was to extend the analysis to surface energy determination of viscoelastic materials. In this analysis, independent rheological measurements are used as the input. As a model system a series of block copolymers with different compositions, hence different microstructures are tested. Effect of chain architecture of block copolymers on their adhesion is the main subject of this thesis. It has been shown how different surface architectures can influence the dynamics of adhesion. Finally, our understanding of adhesion of viscoelastic materials was applied to technologically important materials such as acrylic pressure sensitive adhesives. The surface energy determination of the crosslinked pressure sensitive adhesives (PSA) confirmed the importance of rheological properties on performance of practical (uncrosslinked) PSA that are composition-dependent.

L'invention concerne de nouveaux oligomeres de reticulation de reduction des contraintes, app... more L'invention concerne de nouveaux oligomeres de reticulation de reduction des contraintes, appliques dans les produits de restauration dentaire, les films minces, les revetements durs, les composites, les adhesifs et d'autres utilisations soumises a une reduction des contraintes. Le procede d'addition-fragmentation de reticulation entraine un evenement de transfert de chaine qui permet d'obtenir de nouveaux polymeres qui peuvent etre fonctionnalises davantage. De plus, l'oligomere d'addition-fragmentation comprend des groupes fonctionnels pendants qui se lient a un substrat par formation d'une liaison ionique ou covalente ou qui gravent le substrat par elimination chimique d'une certaine quantite du materiau du substrat.

The objectives of this investigation were to compare the fluoride release and caries inhibition a... more The objectives of this investigation were to compare the fluoride release and caries inhibition ability of resin-modified glass ionomer (RMGI) luting cements. Methods: Materials used for dentin caries inhibition were 3M ESPE RelyX(superscript TM) Luting Plus Cement (REP) paste-paste RMGI, RelyX(superscript TM) Luting Cement (RLC) powder-liquid RMGI and Filtek(superscript TM) Z250 composite/Adper(superscript TM) Single Bond adhesive (ZSB). Rectangular slots (6×2×1 mm) were prepared in 24 dentin blocks cut from 8 bovine roots, and filled with ZSB, RLC, and REP. The specimens were immersed in 10 ml acetic acid solution pH 5.0 (37℃, 3 wks) to create artificial dentin lesion, then sectioned into 400 μm slices and subjected to microradiography. Mineral loss (△Z) was calculated from mineral profiles at 0.5 and 1.0 mm from the material margin, and statistically analyzed (ANOVA, Fisher's, p＜0.05). Fluoride release from cured cement discs (20×1 mm; n=8) in distilled water was measured aft...

Macromolecules, 1994

ABSTRACT

A (e.g. hardenable dental) composition is described comprising (e.g. a first part comprising) an ... more A (e.g. hardenable dental) composition is described comprising (e.g. a first part comprising) an encapsulated material wherein the encapsulated material comprises a basic core material and an inorganic shell material comprising a metal oxide surrounding the core; and (e.g. a second part comprising) water or an acidic component. Also described is an encapsulated material (e.g. suitable for use in a biological carrier material) comprising a basic core material and an inorganic shell material comprising a metal oxide surrounding the core.

L'invention concerne des procedes d'utilisation d'une composition dentaire ayant une ... more L'invention concerne des procedes d'utilisation d'une composition dentaire ayant une teinte photoblanchissable et un composant acide avec un pKa inferieur a 4,5. La teinte photoblanchissable est choisie dans le groupe consistant en les teintes aminoanthraquinone, les teintes azoiques et les combinaisons de celles-ci. La couleur vieillie de la composition dentaire est sensiblement la meme que la couleur de la composition dentaire immediatement apres durcissement.

L'invention concerne des agents d'addition-fragmentation ayant les groupes fonctionnels s... more L'invention concerne des agents d'addition-fragmentation ayant les groupes fonctionnels suivants : 1) un groupe d'addition-fragmentation labile qui peut se cliver et se reformer pour soulager les contraintes, 2) au moins un groupe a haut indice de refraction, et 3) au moins un groupe polymerisable ethyleniquement insature.

Proquest Dissertations and Theses Thesis University of Minnesota 1998 Publication Number Aai9913340 Isbn 9780599118614 Source Dissertation Abstracts International Volume 59 11 Section B Page 5960 182 P, Dec 1, 1998

The immediate goals of this thesis were to make a significant advance in measuring adhesion in th... more The immediate goals of this thesis were to make a significant advance in measuring adhesion in the presence of viscoelastic effects and to understand the relation of structure and surface architecture to adhesion in polymeric systems. Contact mechanics was used as a tool to measure interfacial properties. In this methodology based on the Johnson-Kendall-Roberts (JKR) theory of adhesive contact, two solids of revolution (generally hemispheres) are pressed against each other. The force and contact area are monitored as steps of compression are imposed; the higher the adhesion, the larger the contact area and the lower the force under a given compression. The main feature of this technique is its direct manner of characterization: the surfaces of interest are brought into contact directly. As an integral part of this thesis, an automated apparatus was designed and built to ensure high precision in metrology and good control over experimental conditions. The contact mechanical analysis has originally been developed for elastic materials. The first attempt of this thesis was to extend the analysis to surface energy determination of viscoelastic materials. In this analysis, independent rheological measurements are used as the input. As a model system a series of block copolymers with different compositions, hence different microstructures are tested. Effect of chain architecture of block copolymers on their adhesion is the main subject of this thesis. It has been shown how different surface architectures can influence the dynamics of adhesion. Finally, our understanding of adhesion of viscoelastic materials was applied to technologically important materials such as acrylic pressure sensitive adhesives. The surface energy determination of the crosslinked pressure sensitive adhesives (PSA) confirmed the importance of rheological properties on performance of practical (uncrosslinked) PSA that are composition-dependent.

L'invention concerne de nouveaux oligomeres de reticulation de reduction des contraintes, app... more L'invention concerne de nouveaux oligomeres de reticulation de reduction des contraintes, appliques dans les produits de restauration dentaire, les films minces, les revetements durs, les composites, les adhesifs et d'autres utilisations soumises a une reduction des contraintes. Le procede d'addition-fragmentation de reticulation entraine un evenement de transfert de chaine qui permet d'obtenir de nouveaux polymeres qui peuvent etre fonctionnalises davantage. De plus, l'oligomere d'addition-fragmentation comprend des groupes fonctionnels pendants qui se lient a un substrat par formation d'une liaison ionique ou covalente ou qui gravent le substrat par elimination chimique d'une certaine quantite du materiau du substrat.

The objectives of this investigation were to compare the fluoride release and caries inhibition a... more The objectives of this investigation were to compare the fluoride release and caries inhibition ability of resin-modified glass ionomer (RMGI) luting cements. Methods: Materials used for dentin caries inhibition were 3M ESPE RelyX(superscript TM) Luting Plus Cement (REP) paste-paste RMGI, RelyX(superscript TM) Luting Cement (RLC) powder-liquid RMGI and Filtek(superscript TM) Z250 composite/Adper(superscript TM) Single Bond adhesive (ZSB). Rectangular slots (6×2×1 mm) were prepared in 24 dentin blocks cut from 8 bovine roots, and filled with ZSB, RLC, and REP. The specimens were immersed in 10 ml acetic acid solution pH 5.0 (37℃, 3 wks) to create artificial dentin lesion, then sectioned into 400 μm slices and subjected to microradiography. Mineral loss (△Z) was calculated from mineral profiles at 0.5 and 1.0 mm from the material margin, and statistically analyzed (ANOVA, Fisher's, p＜0.05). Fluoride release from cured cement discs (20×1 mm; n=8) in distilled water was measured aft...

Macromolecules, 1994

ABSTRACT