WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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Access type: Open accessPublisher: search.filters.publisher.Trans Tech Publications

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  • Conference Object
    Citation - Scopus: 2
    Preparation and Characterization of Hydroxyapatite/Calcium Phosphate Powders
    (Trans Tech Publications, 2004) Şimşek, Deniz; Çiftçioğlu, Rukiye; Harsa, Şebnem
    The preparation of calcium phosphate based powders through chemical precipitation in order to determine the optimum conditions for the preparation of stoichiometric, thermally stable hydroxyapatite (HA) powders was investigated in this work. The effects of parameters like pH, aging time, and heat treatment temperature on the phase structure and morphology of the powders were investigated by SEM and XRD.HA was prepared at a Ca/P ratio of 1.67. The precipitation pH had a profound influence on the morphology and crystallite size of the powders in the 4-11 pH range. Relatively large 5 mum prismatic particles were obtained at low pH whereas the powders were formed from agglomerates of nano sized particles at high pH. Powders had a HA dominant phase structure above a pH of 8. Phase pure HA powders were obtained with close to theoretical yields at pH = 10 and 11. The crystallite sizes of the powders varied from about 30 nm at 90degreesC to 50-90 mn at 1250degreesC with the smallest crystallite sizes obtained for pH 10 and 11 powders at 1250degreesC. The crystallite size increased significantly with aging temperature.
  • Article
    Citation - WoS: 18
    Citation - Scopus: 17
    Cnt Incorporated Polyacrilonitrile/Polypyrrole Nanofibers as Keratinocytes Scaffold
    (Trans Tech Publications, 2019) İnce Yardımcı, Atike; Aypek, Hande; Öztürk, Özgür; Yılmaz, Selahattin; Özçivici, Engin; Meşe, Gülistan; Selamet, Yusuf
    Polypyrrole (PPy) is an attractive scaffold material for tissue engineering with its non-toxic and electrically conductive properties. There has not been enough information about PPy usage in skin tissue engineering. The aim of this study is to investigate biocompatibility of polyacrilonitrile (PAN)/PPy nanofibrous scaffold for human keratinocytes. PAN/PPy bicomponent nanofibers were prepared by electrospinning, in various PPy concentrations and with carbon nanotube (CNT) incorporation. The average diameter of electrospun nanofibers decreased with increasing PPy concentration. Further, agglomerated CNTs caused beads and disordered parts on the surface of nanofibers. Biocompatibility of these PAN/PPy and PAN/PPy/CNT scaffolds were analyzed in vitro. Both scaffolds provided adhesion and proliferation of keratinocytes. Nanofiber diameter did not significantly influence the morphology of cells. However, with increasing number of cells, cells stayed among nanofibers and this affected their shape and size. In this study, we demonstrated that PAN/PPy and PAN/PPy/CNT scaffolds enabled the growth of keratinocytes, showing their biocompatibility.
  • Conference Object
    Developing Applications On-Board of Robots With Becerik
    (Trans Tech Publications, 2012) Kumova, Bora İsmail; Takan, Savaş
    Robot applications are mostly first developed on a computer and thereafter loaded onto the robot. However, in many situations, developing applications directly on the robot may be more effective. For instance, children who have not learned using a computer yet and who develop their robot applications while playing. Or for instance in the robots' operating environment, where there is no computer available. In this contribution we present the properties of the software tool becerik, for developing applications on-board a robot and for running them in multi-tasking mode concurrently. Furthermore, we introduce the programming language of the applications that has the same name becerik, which consists of only 6 commands. © (2012) Trans Tech Publications, Switzerland.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 1
    Stabilizing Effect of Biobased Additives on the Thermal Degradation of Pvc
    (Trans Tech Publications, 2010) Egbuchunam, Theresa Obuajulu; Okieimen, Felix Ebhodaghe; Balköse, Devrim
    Novel biobased additives prepared from rubber seed oil were evaluated as thermal stabilizer for PVC. Divalent metal (barium and cadmium) soaps of rubber seed oil were prepared by metathesis in aqueous alcohol and characterized by thermal methods (differential scanning calorimetry and thermogravimetry). The stabilizing effect of the soaps and their admixtures on the thermal degradation of PVC powder and plasticized PVC was examined by dynamic thermogravimetry and dehydrochlorination studies at 160°C using the Thermomat equipment. The metal soaps showed multiple decomposition endotherms but were generally stable (with weight loss less than 5%) within the temperature range (180-220°C) frequently used in the processing of PVC. Using the Broido model, values of apparent activation energy of decomposition of between 50 and 200 kJmol-1 were obtained for the soaps. The biobased additives were found to be relatively effective in stabilizing PVC in powder and plasticized forms against thermal degradation. Using inhibition/retardation time, temperature of incipient decomposition, and temperature at which various extents of decomposition was attained as indices of thermal stabilization, the results from this study indicate a potential for the application of the biobased additives as thermal stabilizer for PVC in rigid and flexible formulations. © (2010) Trans Tech Publications, Switzerland.
  • Conference Object
    Structural Interventions for Conservation of the 15th Century Tahtakale Bath, Tire, Turkey
    (Trans Tech Publications, 2010) Mürtezaoğlu, Fulya; Kaplan, Çağlayan Deniz; İpekoğlu, Başak
    Tahtakale Bath, which is located in the town of Tire in the province of Izmir, Turkey, was constructed in the 15th.century and is one of the outstanding existing examples of Ottoman period baths. The building, which was designed as a double bath, was considerably damaged because of inaccurate interventions after losing its original function, lack of maintenance and natural circumstances. The parts which were reused have considerably lost their original characteristics. This study aims to introduce the construction technique of Tahtakale Bath, which was studied in the scope of a restoration project, and to present the studies on the determination of structural problems, structural strengthening decisions and implementations. Strengthening implementations were carried out in the bathing spaces of the men's section and felt workshop of the building depending on decisions of the restoration project. The original construction technique and materials of the walls, superstructure and architectural details of the building were consolidated by appropriate restoration decisions and implementation works. © (2010) Trans Tech Publications, Switzerland.
  • Conference Object
    Evaluation of Architectural Characteristics for Conservation Decisions of Degirmendagi, Izmir, Turkey
    (Trans Tech Publications, 2010) Kaplan, Çağlayan Deniz; Mürtezaoğlu, Fulya; Akbulut, Özge; İpekoğlu, Başak
    Historical settlements, which are integral parts of the cultural heritage, should be documented and evaluated with their local characteristics. The aim of this study is to document, analyze and evaluate the architectural, environmental and social characteristics of an urban settlement called Deǧirmendaǧı District, which has a historical background beginning with the Roman period to the present, in the center of metropolitan city of İzmir, on the Aegean coast of Turkey. The settlement is one of the earliest that was planned by local administration in İzmir and contributes to the İzmir silhouette with its location on a steep hillside in the township of Konak. Documentation methods used are sketches, photography and architectural and social questionnaires. Inventory cards were prepared to collect architectural characteristics of each building and the social questionnaires were comprised of socio-economic characteristics of the settlers. Data gathered at the site was analyzed and evaluated to develop a conservation approach, including historical review of the ancient era. Since the area is easily accessible and close to city center, the area becomes attractive. It has the advantage of the vista based on its inclined topography and grid-planned scheme. Deǧirmendaǧı District is a special area requiring special conservation within the city of İzmir. However, historical pattern has changed through the years because of changing lifestyle. The area, which is one of the most important and valuable districts in İzmir considering its history, location, and architectural characteristics should be integrated with the city and citizens. This study documents the present potentials and values of the area and forms a basis to prepare conservation approaches.
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 2
    Studies in the Utilization of Biobased Additives as Thermal Stabilizer for Plasticized Pvc
    (Trans Tech Publications, 2009) Okieimen, Felix Ebhodaghe; Egbuchunam, Theresa Obuajulu; Balköse, Devrim
    Divalent metal (barium, cadmium, calcium and zinc) soaps of rubber seed oil and their binary mixtures (BaJCd and CaJZn) and epoxidized rubber seed oil (4.5% epoxide content) and its admixtures with the single divalent metal soaps were evaluated as thermal stabilizer for dioctylphthalate plasticized PVC using changes in discolouration indices (yellowness index and UV absorption at 360nm) and initial rates of dehydrochlorination measured at 140 and 160°C. The results obtained showed that the divalent metal soaps were relatively effective in stabilizing the dioctylphthalate plasticized PVC against thermal degradation and that the binary soap mixtures enhanced the heat stabilizing effectiveness: marked reduction in the values of the discolouration indices; longer dehydrochiorination induction period and smaller values of rate constant of initial rate of dehydrochlorination. It was found that epoxidized rubber seed oil was less effective in comparison with the divalent metal soaps in stabilizing plasticized PVC against thermal degradation. These results show that the bio-based additives are compatible with dioctylphthalate plasticized PVC, stable to heat within the range of temperature used in the processing of plasticized PVC, inhibitlretard dehydrochlorination and reduce the extent of degradation.
  • Conference Object
    Microstructure-Performance Relation in Pmma-Based Open-Cell Porous Materials for High Pressure Ceramic Sanitaryware Casting
    (Trans Tech Publications, 2004) Ergün, Yelda; Dirier, C.; Yılmaz, M.; Tokman, C.; Tanoğlu, Metin
    The ceramic whiteware/sanitaryware industry is rapidly undergoing to implement high-pressure casting techniques for ceramic article production. In these techniques, materials with open pore microstructure that allows drainage of water under applied pressure are needed. The polymethyl methacrylate (PMMA) based polymeric porous materials have become the most suitable type of materials for this purpose because of their short casting periods and high service lives. However, the superior service life and performance of these materials are closely related to the microstructure. In the present study, the porous materials with various compositions of the constituents in the emulsion were produced to effect the microstructure of PMMA-based materials. The variations on the pore microstructure were interrelated to the performance of the material for high-pressure sanitaryware casting. The pore morphology and water permeability of the samples was measured using optical and SEM microscopy and permeability measurement techniques, respectively. The compressive collapse stress and modulus values were determined by performing compression testing. The results showed a significant interrelation between microstructure and the performance of the PMMA-based ceramic mould materials.
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 2
    Investigation of the Permeability of Pure Gases in Sol-Gel Derived Al 2o 3 Membrane
    (Trans Tech Publications, 2004) Topuz, Berna; Çiftçioğlu, Muhsin; Özkan, Fehime
    The preparation, characterization and pure gas permeation of sol-gel derived alumina membranes were investigated in this work. The effects of acid concentration/type and water content on the particle size in the sols and pore size distributions of the unsupported membrane were investigated by N 2 adsorption/desorption isotherms and Dynamic Light Scattering. Increasing the H +/Al 3+ mole ratio from 0.1 to 0.25 caused the hydrodynamic sol particle size and BJH pore size to decrease from 65 to 30 nm and 3.6 to 2.9 nm, respectively. The pore size increased from 2.8 nm to 3 nm upon increasing the calcination temperature from 500 to 600°C. Unsupported membranes were heat treated in the 200 to 1200 °C range for the characterization of the phase structure. Pinhole and crack free alumina membranes about 3 μm (2-layer) in thickness was observed from the SEM pictures with insignificant infiltration. The CO 2 permeability through the double layer γ-Al 2O 3 membrane calcined at 600 °C was 2.25*10 -7 mol/m 2.s.Pa, and had a slight pressure dependence indicating Knudsen Diffusion and Laminar Flow being the effective transport mechanisms. Upon the calcination of a similar 2-layer alumina membrane at 500°C, the CO 2 permeability decreased to 1.51 *10 -8 mol/m 2.s.Pa. without pressure dependence.
  • Conference Object
    Citation - WoS: 7
    Citation - Scopus: 7
    Investigation of the Pozzolanic Properties of Bricks Used in Horasan Mortars and Plasters in Historic Buildings
    (Trans Tech Publications, 2004) Böke, Hasan; Akkurt, Sedat; İpekoğlu, Başak
    Crushed brick used in historic brick-lime mortars and plasters (Horasan) were characterized for understanding their properties to develop intervention mortars for conservation. Brick powders were separated from original mortars and plasters, and analyzed by XRD, SEM-EDS, TGA and pozzolanic activity (PA) measurements. The results showed that the microstructures of brick powders were not completely vitrified, and their XRD analysis failed to show the peaks for high temperature (T>900°C) phases. PA measurements of all brick powders showed an ample amount of artificial pozzolan property. Consequently, brick powders aimed for conservation of historic mortars must have high clay contents in addition to being low-fired (T<900°C) in order to produce maximum conversion into amorphous phase for ideal PA values.