Calcium and Magnesium Contents in Three Hypericum L. Species from Turkey

Gozde Elgin Cebe,Ozlem Sogut 한국식품영양과학회 2018 Journal of medicinal food Vol.21 No.8

Hypericum L. (Hypericaceae), which has 400 species in the world and 96 species in Turkey, has grown in Europe, Asia, North Africa, and America. Hypericum species have antidepressant, analgesic, spazmolytic, anti-inflammatory, antiviral, and wound healing effects. The purpose of this study was to analyze the magnesium (Mg) and calcium (Ca) contents of three Hypericum species (Hypericum perforatum L., Hypericum triquetrifolium Turra, and Hypericum empetrifolium Willd.) collected from the western part of Turkey. Analyses were done by atomic absorption spectrometer using convenient conditions. Mg and Ca concentrations were determined in three Hypericum species. Mg levels were determined as 1.053 ± 0.09, 0.792 ± 0.06, and 0.798 ± 0.17 mg.g−1 and Ca levels were determined as 0.573 ± 0.19, 0.433 ± 0.06, and 0.329 ± 0.005 mg.g−1 in H. perforatum L., H. triquetrifolium Turra, and H. empetrifolium Willd., respectively. The sedative effect of the drug is compensated with the metal concentration observed from the analysis, which shows that high Mg levels overlap with the sedative effect of the drug.

Evaluation of the bond strength between aged composite cores and luting agent

Polat, Serdar,Cebe, Fatma,Tuncdemir, Aliriza,Ozturk, Caner,Usumez, Aslihan The Korean Academy of Prosthodonitics 2015 The Journal of Advanced Prosthodontics Vol.7 No.2

PURPOSE. The aim of this study was to evaluate effect of different surface treatment methods on the bond strength between aged composite-resin core and luting agent. MATERIALS AND METHODS. Seventy-five resin composites and also seventy-five zirconia ceramic discs were prepared. 60 composite samples were exposed to thermal aging (10,000 cycles, 5 to $55^{\circ}C$) and different surface treatment. All specimens were separated into 5 groups (n=15): 1) Intact specimens 2) Thermal aging-air polishing 3) Thermal aging- Er:YAG laser irradiation 4) Thermal aging- acid etching 5) Thermal-aging. All specimens were bonded to the zirconia discs with resin cement and fixed to universal testing machine and bond strength testing loaded to failure with a crosshead speed of 0.5 mm/min. The fractured surface was classified as adhesive failure, cohesive failure and adhesive-cohesive failure. The bond strength data was statistically compared by the Kruskal-Wallis method complemented by the Bonferroni correction Mann-Whitney U test. The probability level for statistical significance was set at ${\alpha}$=.05. RESULTS. Thermal aging and different surface treatment methods have significant effect on the bond strength between composite-resin cores and luting-agent (P<.05). The mean baseline bond strength values ranged between $7.07{\pm}2.11$ and $26.05{\pm}6.53$ N. The highest bond strength of $26.05{\pm}6.53$ N was obtained with Group 3. Group 5 showed the lowest value of bond strength. CONCLUSION. Appropriate surface treatment method should be applied to aged composite resin cores or aged-composites restorations should be replaced for the optimal bond strength and the clinical success.

Kinetics of esterification of propionic acid with n-amyl alcohol in the presence of cation exchange resins

Beyhan Erdem,Mustafa Cebe 한국화학공학회 2006 Korean Journal of Chemical Engineering Vol.23 No.6

of n-amyl alcohol with propionic acid catalyzed by macroporous (Amberlyst-15) and micro-When these catalysts were used as commercially available, Amberlyst-15 was observed to be the most effective catalystwith respect to rate constants, but after drying it became the less effective one. The reaction rate increased with increasein catalyst concentration and reaction temperature. Stirrer speed and different mesh sizes had virtually no effect on therate under the experimental conditions. The effect of divinylbenzene content was examined for the microporous resinDowex 50 W, and the results showed that the propionic acid conversion decreased as the divinylbenzene content wasincreased. The rate data were correlated with a second-order homogeneous reaction model. The apparent activationenergies, reaction enthalpies and entropy values were calculated for each catalyst. Reaction monitoring is simple and% 2.54.

Evaluation of the bond strength between aged composite cores and luting agent

Caner Ozturk,Alirıza Tuncdemir,Aslıhan usumez,Fatma Cebe,Serdar Polat 대한치과보철학회 2015 The Journal of Advanced Prosthodontics Vol.7 No.2

PURPOSE The aim of this study was to evaluate effect of different surface treatment methods on the bond strength between aged composite-resin core and luting agent. MATERIALS AND METHODS Seventy-five resin composites and also seventy-five zirconia ceramic discs were prepared. 60 composite samples were exposed to thermal aging (10,000 cycles, 5 to 55℃) and different surface treatment. All specimens were separated into 5 groups (n=15): 1) Intact specimens 2) Thermal aging-air polishing 3) Thermal aging- Er:YAG laser irradiation 4) Thermal aging- acid etching 5) Thermal-aging. All specimens were bonded to the zirconia discs with resin cement and fixed to universal testing machine and bond strength testing loaded to failure with a crosshead speed of 0.5 mm/min. The fractured surface was classified as adhesive failure, cohesive failure and adhesive-cohesive failure. The bond strength data was statistically compared by the Kruskal-Wallis method complemented by the Bonferroni correction Mann-Whitney U test. The probability level for statistical significance was set at α=.05. RESULTS Thermal aging and different surface treatment methods have significant effect on the bond strength between composite-resin cores and luting-agent (P<.05). The mean baseline bond strength values ranged between 7.07 ± 2.11 and 26.05 ± 6.53 N. The highest bond strength of 26.05 ± 6.53 N was obtained with Group 3. Group 5 showed the lowest value of bond strength. CONCLUSION Appropriate surface treatment method should be applied to aged composite resin cores or aged-composites restorations should be replaced for the optimal bond strength and the clinical success.

Water-Stable Silk Films with Reduced &bgr;-Sheet Content

Jin, H.-J.,Park, J.,Karageorgiou, V.,Kim, U.-J.,Valluzzi, R.,Cebe, P.,Kaplan, D. L. WILEY-VCH Verlag 2005 Advanced Functional Materials Vol.15 No.8

<P>Silk fibers have outstanding mechanical properties. These fibers are insoluble in organic solvents and water, are biocompatible, and exhibit slow biodegradation in vitro and in vivo due to the hydrophobic nature of the protein and the presence of a high content of &bgr;-sheet structure. Regenerated silk fibroin can be processed into a variety of materials normally stabilized by the induction of &bgr;-sheet formation through the use of solvents or by physical stretching. To extend the biomaterial utility of silk proteins, options to form water-stable silk-based materials with reduced &bgr;-sheet formation would be desirable. To address this need for more rapidly degradable silk biomaterials, we report the preparation of water-stable films from regenerated silk fibroin solutions, with reduced &bgr;-sheet content. The keys to this process are the preparation of concentrated (8 % by weight) aqueous solutions of fibroin and a subsequent water-based annealing procedure. These new materials degrade more rapidly due to the reduced &bgr;-sheet content, as determined in vitro via enzymatic hydrolysis, yet support human adult stem-cell expansion in vitro in a similar or improved fashion to the crystallized proteins in film form. These new silk-based materials extend the range of biomaterial properties that can be generated from this unique family of proteins.</P> <B>Graphic Abstract</B> <P>In order to extend the utility of silk-based biomaterials, water-stable films with reduced &bgr;-sheet formation have been formed via a water-annealing process, leading to improved biodegradability and elasticity. The Figure shows a) a fracture surface (scale: 100 &mgr;m), b) a layer from the film surface (scale: 20 &mgr;m), and c) individual layer thickness (scale: 100 nm). <img src='wiley_img/1616301X-2005-15-8-ADFM200400405-content.gif' alt='wiley_img/1616301X-2005-15-8-ADFM200400405-content'> </P>