Elif Hilal Soylu

Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness.

PURPOSE The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 × 2 × 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukeys HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant. RESULTS The general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 ± 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 ± 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 Å). CONCLUSION After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic substructures. The dentists should be familiar with the materials that are used in clinic for prosthodontics treatments.

Formulation and characterization of liquid crystal systems containing azelaic acid for topical delivery.

Purpose: The aim of this study is to prepare and characterize azelaic acid (AzA) containing liquid crystal (LC) drug delivery systems for topical use. Methods: Two ternary phase diagrams, containing liquid paraffin as the oil component and a mixture of two nonionic surfactants (Brij 721P and Brij 72), were constructed. Formulations chosen from the phase diagrams were characterized by polarized light microscopy, rheological analyses, differential scanning calorimetry (DSC), and small angle x-ray scattering spectroscopy. Results: Polarized light microscopy proved that except the oil/water emulsion (O/W E), other formulations showed lamellar LC structure. In vitro release studies indicated that the fastest release was achieved by the Lamellar LC (LLC) and O/W E systems, whereas slower release was obtained from the emulsion containing lamellar LC (E-LLC) and distorted lamellar LC (D-LLC) systems. Results of rheological measurements both supported the results of in vitro release studies and showed that the emulsion containing the LC (E-LLC) system had the most stable structure. The formulations and their effect on stratum corneum (SC) were evaluated by DSC studies. The lamellar LC (LLC), emulsion containing lamellar liquid crystal (E-LLC), and O/W E formulations had an effect on both lipid and protein components of SC, whereas distorted lamellar liquid crystal (D-LLC) system had an effect on only the lipid components of SC. Conclusions: LLC systems could be considered promising for the topical delivery of AzA.

X-ray scattering and diffraction studies on spider silk cocoons

25th European Crystallographic Meeting, ECM 25, İstanbul, 2009 Acta Cryst. (2009). A65, s 337 Page s 337 FA5-MS06-P01 X-ray Scattering and Diffraction Studies on Spider Silk Cocoons. Elif Hilal Soylua, Semra Ideb, Tuncay Turkesc, Neslihan Kocateped, Orhan Mergend, Omer Celike. aKaradeniz Technical University, Faculty of Science & Literature, Department of Physics, Trabzon -Turkey. bHacettepe University, Fac. of Engineering, Dept. of Physics Eng. 06800 Beytepe-Ankara, Turkey. cNigde University, Faculty of Science, Department of Biology, Nigde-Turkey. dHacettepe University, Faculty of Science, Department of Biology, 06800 Beytepe-Ankara, Turkey. eHarran University, Faculty of Science and Art, Dept. of Physics, 63300 Sanlıurfa, Turkey. E-mail:elifsoylu_ph@yahoo.com