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    Effects of Different Acids and Etching Times on the Bond Strength of Glass Fiber-Reinforced Composite Root Canal Posts to Composite Core Material
    (2012) Güler, A. U.; Kurt, M.; Duran, I.; Uludamar, A.; İnan, O.
    Objective: To investigate the effects of different acids and etching times on the bond strength of glass fiber-reinforced composite (FRC) posts to composite core material. Method and Materials: Twenty-six FRC posts (FRC Postec Plus) were randomly divided into 13 groups (each n = 2). One group received no surface treatment (control). The posts In the other groups were acid etched with 35% phosphoric acid and 5% and 9.6% hydro- fluoric acid gel for four different etching times (30. 60. 120. and 180 seconds). A cylindric polytetrafluoroethylene mold was placed around the treated posts and filled with dual-cure composite core material (MultiCore Flow). All samples were light cured for 60 seconds. After 24 hours of water storage, the specimens were sectioned perpendicularly to the bonded interface under water cooling to obtain 2-mm post-and-core specimens. Eight specimens were made from each group. Push-out tests were performed at a crosshead speed of 0.5 mm/min using a universal testing machine. Data were analyzed by one-way ANOVA followed by the Tukey honestly significant difference test (ot = .05). Results: The lowest bond strength was observed in the control group (12.51 megapascal [MPa]). No statistical significant difference was observed among group H5-120 (20.31 MPa). group H9-120 (20.55 MPa). or group P-180 (20.57 MPa) (P > .05). These groups demonstrated the highest bond strength values (P < .05). Conclusion: For the FRC posts, all acid-etch- ing procedures tested showed significantly increased bond strength when compared with the control group. Acid-etching with 5% hydrofluoric acid and 9.6% hydrofluoric acid for 2 minutes and with 35% phosphoric acid for 3 minutes (groups H5-120. H9-120. and P-180. respectively) demonstrated the highest bond strength values between the FRC post and composite core material. Although the bond strength was increased by prolonged acid etching, the micro structure of the FRC posts might have been damaged. © 2012 by Quintessence Publishing Co Inc.
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    Electrical Characterization of Interdigitated Humidity Sensors Based on CNT Modified Calixarene Molecules
    (POLISH ACAD SCIENCES INST PHYSICS, 2013) Ozbek, C.; Culcular, E.; Okur, S.; Yilmaz, M.; Kurt, M.
    In this study, we report on the optimization and characterization of chloroform soluble calix[4]arene derivative as a humidity sensor based on electrical properties. Due to the fact that calix[4]arene molecules are nonconductive, we modified the calix[4]arene molecules with carbon nanotubes with electrostatic bond in order to increase the conductance of calix[4]arene molecule (5,11,17,23-tetra-ter-butyl-25,27-dehydrazinamidcarbonilmetoxy-26,28-dehydroxy-kalix[4]aren). Using photolithography technique, we fabricated interdigitated gold electrodes with 3 micrometers separation to investigate the electrical properties of carbon nanotubes modified calix[4]arene molecule where we used dropcast method to form a thin film of carbon nanotubes modified calix[4]arene molecule on the gold electrodes. Our reproducible experimental results indicated that the chloroform soluble carbon nanotubes modified calix[4]arene films have great potential for humidity sensing applications at room temperature operations. DOI: 10.12693/APhysPolA.123.461
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    Synthesis, FT-IR, FT-Raman, dispersive Raman and NMR spectroscopic study of a host molecule which potential applications in sensor devices
    (PERGAMON-ELSEVIER SCIENCE LTD, 2012) Kurt, M.; Karabacak, M.; Okur, S.; Sayin, S.; Yilmaz, M.; Sundaraganesan, N.
    The solid phase FT-IR, FT-Raman and dispersive Raman spectra of the host molecule which potential applications in sensor devices have been recorded in the region 400-4000 and 50-3500 cm(-1), respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (DFF) using B3LYP method with 6-31G(d) basis set. The vibrational frequencies were calculated for the studied molecule by DFT method, and compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. Finally the calculation results were applied to simulate infrared and Raman spectra of the compound. Obtained these spectra also showed good agreement with observed spectra. The dipole moment, linear polarizability and first hyperpolarizability values were also computed. The linear polarizability and first hyperpolarizability of the studied molecule indicate that the compound is a good candidate of nonlinear optical materials. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.