WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
Browse
Search Results
Article Citation - WoS: 19Citation - Scopus: 18Biyomalzeme Yüzeylerinden İzole Edilen Metisiline Dirençli Staphylococcus Aureus Suşlarında Virülans Genlerinin Araştırılması(Ankara Microbiology Society, 2008) Sudağıdan, Mert; Çavuşoğlu, Cengiz; Bacakoğlu, FezaStafilokoklar, biyomalzeme kaynaklı nozokomiyal enfeksiyonların en önemli etkenlerindendir. Bu çalışmada, Göğüs Hastalıkları Yoğun Bakım Ünitesi (YBÜ)'nde yatan 48 hastada kullanılan polimerik biyomalzeme yüzeylerinden izole edilen metisiline dirençli 11 Staphylococcus aureus suşunda virülans genlerinin varlığının saptanması ve bunların bazılarının fenotipik ifadelerinin araştırılması amaçlanmıştır. Çalışmamızda polimeraz zincir reaksiyonu (PCR) ile özgül primerler kullanılarak, bağlanma ve biyofilm oluşumundan sorumlu genler (icaA, icaC, bap), metisilin direnç geni (mecA), enterotoksin A-E üretiminden sorumlu genler (sea, seb, sec, sed, see), toksik şok sendromu toksini geni [tst), eksfoliatif toksin A ve B genleri (eta ve etb), alfa ve beta-hemolizin genleri (hla ve hlb), stafilokokal ekzotoksin benzeri protein-1 geni (sef1), proteaz genleri (sspA, sspB, aur, serine proteaz geni), lipaz geni (geh) ve regülatör genler (sarA ve agrCA) araştırılmıştır. Ayrıca suşların fenotipik olarak biyofilm oluşturma, antibiyotik duyarlılık, proteaz ve lipaz üretimi gibi özellikleri de değerlendirilmiştir. Biyofilm testlerinde, biyofilm yapan ve "slime" üreten suşlara rastlanmamış, ancak tüm suşların biyofilm yapımında rol oynayan icaA genine sahip olduğu bulunmuştur. Bununla birlikte biyofilm yapımında rol oynayan icaC ve bap genleri tespit edilememiştir. Tüm suşlarda mecA geninin varlığı saptanmış ve suşların hepsinin oksasilin, penisilin G ve gentamisine; 10'unun eritromisine ve dokuzunun da ofloksasine dirençli olduğu bulunmuştur. İzolatların tümü vankomisin, teikoplanin ve ko-trimoksazole duyarlı olarak saptanmıştır. Ekzotoksin ve regülatör genlerinin taranması sonucunda, suşların sea, seti, hla, hlb ve sarA genlerini taşıdığı belirlenmiştir. PCR ile tüm suşların, çalışılan bütün proteaz genlerine (sspA, sspB, aur ve serin proteaz geni) sahip olduğu görülmüş, ancak sütlü (skim milk ve milk agar) ve kazein ağarlarda yapılan proteaz üretimi testlerinde negatif sonuç alınmıştır. Lipaz üretiminin belirlenmesi için Tween 20, Tween 80 ve tributyrin içeren besiyerleri kullanılmış ve tüm suşlarda geç dönemde (inkübasyonun üçüncü günü) pozitif sonuç alınmasına karşın, izolatların hiçbirisinde lipaz üretiminden sorumlu geh geni bulunmamıştır. Sonuç olarak, biyomalzeme yüzeylerinden izole edilen S.aureus suşlarında, araştırılan virülans genlerinden bazılarının varlığı saptanmış, ancak bunların tam olarak fenotipe yansımadığı izlenmiştir. İzolat sayısının azlığına ve tüm genlerin ekspresyonlarının fenotipik olarak çalışılamamış olmasına rağmen, bu genlerin varlığının yoğun bakım hastalan için potansiyel bir risk teşkil edebileceği düşünülmüştür.Conference Object Citation - Scopus: 2Preparation and Characterization of Hydroxyapatite/Calcium Phosphate Powders(Trans Tech Publications, 2004) Şimşek, Deniz; Çiftçioğlu, Rukiye; Harsa, ŞebnemThe 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.Conference Object Citation - WoS: 7Citation - Scopus: 7Carbon Deposition on the Stainless Steels Substrates Using Pulsed Plasma(National Institute of Optoelectronics, 2008) Pat, Suat; Balbağ, Zafer; Cenik, I.; Ekem, Naci; Okur, Salih; Vladoiu, Rodica; Musa, GeavitWe have developed a generic method for carbon deposition method for any substrates from methane pulsed plasma. The generic method has been developed for carbon deposition on the stainless steels substrates using pulsed methane plasma. Pulsed plasma was produced at atmospheric pressure methane gas and room temperatures. Methane plasma was generated using with 25kV, 25kHz pulsed power supply. Discharge current approximately 300 mA. Stainless steels probes hold in the 32mm from the methane plasma. Probes dimensions were phi=30mm, h=8mm and 4 mm.Conference Object Citation - Scopus: 1Enterprise Systems Applications Development Plans To Build and Develop Robust and Environmentally Sensitive Green Logistics Systems Management Software(Springer Verlag, 2009) Yıldız, Türkay; Yercan, FundaWithin the concept of enterprise-wide development of environmentally sensitive systems' application modules to fully integrate all-in-one green logistics services principles have received much attention and consideration from practitioners, academia, and from the industry, for about more than a decade. However, by taking into the consideration of the multidisciplinary nature of the issue, large scale effective collaborative framework is needed to be developed. Therefore, utilization of UML diagrams, class definitions, defining class relationships, fields, tables, views, etc. so on play crucial roles in the design phases of the enterprise system. Thus, this article largely deals with the major logistics work processes and their interactions within the consideration of environmental engineering issues on business operations to address step-by-step process control mechanisms to provide necessary input to build robust-design and better implementation of the needed IT software backbone.Conference Object The Effect of Ag and Ag Plus N Ion Implantation on Cell Attachment Properties(American Institute of Physics, 2009) Urkaç, Emel Sokullu; Öztarhan, Ahmet; Tıhmınlıoğlu, Funda; Deliloğlu, İsmet Gürhan; İz, Sultan Gülce; Oks, Efim; Ila, DaryushImplanted biomedical prosthetic devices are intended to perform safely, reliably and effectively in the human body thus the materials used for orthopedic devices should have good biocompatibility. Ultra High Molecular Weight Poly Ethylene (UHMWPE) has been commonly used for total hip joint replacement because of its very good properties. In this work, UHMWPE samples were Ag and Ag+N ion implanted by using the Metal-Vapor Vacuum Arc (MEVVA) ion implantation technique. Samples were implanted with a fluency of 1017 ion/cm2 and extraction voltage of 30 kV. Rutherford Backscattering Spectrometry (RBS) was used for surface studies. RBS showed the presence of Ag and N on the surface. Cell attachment properties investigated with model cell lines (L929 mouse fibroblasts) to demonstrate that the effect of Ag and Ag+N ion implantation can favorably influence the surface of UHMWPE for biomedical applications. Scanning electron microscopy (SEM) was used to demonstrate the cell attachment on the surface. Study has shown that Ag+N ion implantation represents more effective cell attachment properties on the UHMWPE surfaces.Conference Object Thermal Behaviour of W Plus C Ion Implanted Ultra High Molecular Weight Polyethylene (uhmwpe)(American Institute of Physics, 2009) Urkaç, Emel Sokullu; Öztarhan, Ahmet; Tıhmınlıoğlu, Funda; Ila, Daryush; Budak, S.; Chhay, B.; Nikolaev, A.The aim of this work was to examine thermal behavior of the surface modified Ultra High Molecular Weight Poly Ethylene (UHMWPE) in order to understand the effect of ion implantation on the properties of this polymer which is widely used especially for biomedical applications. UHMWPE samples were Tungsten and Carbon (W+C) hybrid ion implanted by using Metal Vapour Vacuum Arc (MEVVA) ion implantation technique with a fluence of 10 17 ions/cm2 and extraction voltage of 30kV. Untreated and surface-treated samples were investigated by Rutherford Back Scattering (RBS) Analysis, Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) Spectrometry, Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). This study has shown that ion implantation represents a powerful tool on modifying thermal properties of UHMWPE surfaces. This combination of properties can make implanted UHMWPE a preferred material for biomedical applications.Conference Object Structural and Thermal Characterization of Ti+o Ion Implanted Ultrahigh Molecular Weight Polyethylene (uhmwpe)(American Institute of Physics, 2009) Öztarhan, Ahmet; Urkaç Sokullu, Şadiye Emel; Tıhmınlıoğlu, Funda; Kaya, N.; Ila, Daryush; Budak, S.; Nikolaev, A.In this work, Metal-Gas Hybrid Ion Implantation technique was used as a tool for the surface modification of Ultra High Molecular Weight Polyethylene (UHMWPE). Samples were Ti + O ion implanted by using Metal-Vapour Vacuum Arc (MEVVA) ion implanter to a fluence of 5x10(16) ion/cm(2) for each species and extraction voltage of 30 kV. Untreated and surface treated samples were investigated by Rutherford Back Scattering (RBS) Spectrometry, Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) Spectroscopy, Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Results indicate that Ti + O ion implantation can be applied on UHMWPE surfaces successfully. ATR-FTIR spectra indicate that the C-H concentration on the surface decreased after Ti + O implantation. Thermal characterization with TGA and DSC shows that polymeric decomposition temperature is shifted after ion implantation.Article Citation - WoS: 1Citation - Scopus: 1ANN model predicts floor tile properties(American Ceramic Society, 2004) Akkurt, Sedat; Özcan, Selçuk[No abstract available]Article Citation - WoS: 5Citation - Scopus: 7Effect of the Zeolite Filler on the Thermal Degradation Kinetics of Polypropylene(Scibulcom Ltd., 2006) Tıhmınlıoğlu, Funda; Pehlivan, Hilal; Balköse, Devrim; Ülkü, SemraIn this study, the thermal degradation behaviour of polypropylene (PP) and polypropylene-zeolite composites was investigated. Clinoptilolite, a natural zeolitic tuff, was used as the filling material into the composites. Effect of both pure clinoptilolite and silver ion exchanged form of clinoptilolite addition on the thermal degradation kinetics of polypropylene composites was studied by using differential scanning calorimetry (DSC) and thermal gravimetry analysis (TGA) techniques. Polymer degradation was evaluated by using DSC with heating rates of 5, 10, and 20 degrees C/ min from room temperature up to 500 degrees C. Silver concentration (4.36, 27.85 and 183.8 mg Ag/g zeolite) was the selected parameter under consideration. From the DSC curves, it was observed that the heat of degradation values of the composites containing 2-6% silver exchanged zeolites (321-390 kJ/kg) were larger compared to that of the pure PP free of silver and zeolite (258 kJ/kg). From the DSC results it was confirmed that PP-zeolite composites can be used at higher temperatures compared to the pure PP polymer because of its higher thermal stability. The thermal decomposition activation energies of the composites were calculated by using both the Kissenger and Ozawa models. The values predicted from these two equations were in close agreement. From the TGA curves, it was found that zeolite addition into the PP matrix speeds down the decomposition reaction, however, silver exchanged zeolite addition into the matrix accelerates the reaction. The higher the silver concentration, the lower the thermal decomposition activation energies were obtained. As a result, PP was found to be much more susceptible to thermal decomposition in the presence of silver exchanged zeolite.Article Citation - WoS: 2Citation - Scopus: 14Dynamic Modelling for Planar Extensible Continuum Robot Manipulators(ACTA Press, 2009) Tatlıcıoğlu, Enver; Walker, I. D.; Dawson, D. M.In this paper, a new dynamic model for continuum robot manipulators is derived. The dynamic model is developed based on the geometric model of extensible continuum robot manipulators with no torsional effects. The development presented in this paper extends the previously available models to include a class of extensible continuum robot manipulators. First, the kinetic energy of a slice of the continuum robot is evaluated. Next, the total kinetic energy of the manipulator is obtained by utilizing a limit operation (i.e., sum of the kinetic energy of all the slices). Then, the gravitational potential energy of the manipulator is derived. Next, the elastic potential energy of the manipulator is derived for both bending and extension. Finally, the dynamic model of a planar 3-section extensible continuum robot manipulator is derived by utilizing the Lagrange representation. Numerical simulation results are presented for a planar 3-section extensible continuum robot manipulator.