Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Department: search.filters.department.Thesis (Master)--İzmir Institute of Technology, ChemistrySubject: search.filters.subject.Nanotechnology

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Now showing 1 - 4 of 4
  • Master Thesis
    Hydrothermal Preparation of Single Crystalline Ceo2 Nanoparticles and the Influence of Alkali Hydroxides on Their Structure and Optical Behavior
    (Izmir Institute of Technology, 2009) Kepenekci, Özlem; Emirdağ Eanes, Mehtap; Eanes, Mehtap; Eanes, Mehtap; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Single crystalline cerium oxide nanoparticles were synthesized via hydrothermal method by mixing aqueous solution of cerium nitrate [Ce(NO3)3.6H2O] with an alkali base. Several characterization methods were used to identify morphology and crystalline nature such as X-ray Diffraction, Scanning and Transmission Electron Microscopes. This study is divided into three parts. In the first part, some controlling parameters like, that were affecting size and shape of CeO2 nanoparticles, were studied. It was found that size of CeO2 nanoparticles increased when increasing both reaction time and temperature. Alkali base concentration promoted the particle growth. Also, particle morphology was more uniform rather than aggregated in presence of higher concentrated alkali base. When the alkali base type was changed, the use of NaOH produced larger cubic nanocrystals of CeO2 than KOH and LiOH.Second part is related to determine the optical properties of CeO2 nanoparticles. Based on the UV-Vis and Fluorescence Spectroscopy results, size, bandgap and defect level of CeO2 nanoparticles can be easily determined. Nanoparticles in presence of NaOH alkali base were found to produce less defective CeO2 nanoparticles as compared to KOH and LiOH. The last part of this work is to evaluate the shape effect on morphology, size and optical properties of CeO2 nanoparticles. Rod crystals of CeO2 were produced when the hydrothermal synthesis temperature was low (120°C) or when the reaction time was short (1 hour). When the synthesis temperature was higher than 160°C well defined cubic crystals of CeO2 started to form.
  • Master Thesis
    Production and Characterization of Water Soluble Cdsete Based Core/Shell Nanocrystals and Their Applications in Bioimaging
    (İzmir Institute of Technology, 2009) Özdemir, Seda; Özçelik, Serdar; Özçelik, Serdar; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    In recent years, nanotechnology has become one of the most intensively studied fields. At the nanometer scale, materials have unique electrical, optical, magnetic and chemical properties. They can be used for a wide variety of applications such as electrooptical devices, tagging and medical applications. The goal of this study was to produce water-dispersible alloyed CdSexTe1-x semiconductor nanocrystals, which are suitable to interact with biomolecules. CdSexTe1-x nanocrystals were synthesized by a single step aqueous synthesis method. Monodisperse, CdSexTe1-x nanocrystals with zinc blende structure were obtained in water. Synthesized nanocrystals emit in the range from 528 nm to 620 nm. CdSexTe1-x nanocrystals have 17% photoluminescence quantum yield, after the CdS shell coating the photoluminescence quantum yield increased up to 22%. MTT test and Trypan Blue tests were used to evaluate the toxicity of CdSexTe1-x nanocrystals. MTT measurements reveal that the MCF7 cancer cells are not affected by the nanocrystals at any dosage and exposure condition, but lethal effects are determined at the concentration of 1.0ug/ml for the PC3 cells. The BEAS 2B cells are very sensitive to the nanocrystals and do not proliferate at concentration of 0.5ug/ml. Confocal microscopy studies show that the nanocrystals has ability to penetrate to the cytoplasm of cells.
  • Master Thesis
    Development of a Novel Electrocardiography Sensor Based on a Composite Silver Chloride Nanoparticles and Polyaniline
    (Izmir Institute of Technology, 2013) Taşcıoğlu, Didem; Özçelik, Serdar; Taşcıoğlu, Didem; Özçelik, Serdar; 04.01. Department of Chemistry; 01. Izmir Institute of Technology; 04. Faculty of Science
    The electrical activity of the heart is detected by electrodes attached to the surface of the skin. These electrodes detect bioelectrical signals in the human body. Physilogical status of heart condition especially cardiovascular diseases and disturbances in the cardiac rthym are recorded by electrocardiography (ECG). Despite the fact that the usage of disposable ECG electrodes in our country is substantial nearly as 70 million in 2010, these electrodes are not fabricated in Turkey. In the scope of this study, it was aimed to develop a novel sensor based on synthesized AgCl/Polyaniline nanocomposites for ECG electrodes. In this study, the production of silver chloride (AgCl) nanoparticles was achieved by the polyol method. ABS (Acrylonitrile butadiene styrene) was used as a supporting material of the ECG electrode. Synthesized AgCl nanoparticles were not easily adsorbed on the surface of ABS. We develop a synthetic chemistry to perform simultaneous synthesis of AgCl nanoparticle and polymerization of aniline on surface of ABS. Polyaniline acts as a chemical linker between the nanoparticle and ABS surface in the same batch reactor. The synthesized composite based on polyaniline and AgCl nanoparticles completely covers the surface of ABS. To evaluate electrodes, we fabricated a disposable ECG electrode and compared it with the disposable electrodes that are commercially available. The electrocardiography data indicated that the fabricated electrodes were demonstrated a performance which is comparable with the commercial electrodes. The results demonstrate that a novel ECG electrodes can be manufactured based on this new composite material and method develop in our laboratory.
  • Master Thesis
    Rendering Optical and Structural Properties of Semiconductor Nanocrystals by Chemical Doping
    (Izmir Institute of Technology, 2012) Sevim, Seçil; Özçelik, Serdar; Özçelik, Serdar; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    Semiconductor nanocrystals are widely used in technologic applications because of their unusual and tunable optical properties. In this study we synthesized two type of semiconductor nanocrystals by the aqueous synthesis method. Colloidal HgCdTe semiconductor nanocrystals were synthesized by cation exchange reaction at room temperature. The absorption and photoluminescence spectra of water dispersible semiconductor nanocrystals appeared in NIR range of the electromagnetic spectrum. Aging process showed higher shift to red region in absorption and fluorescence spectra for HgCdTe nanocrystals. Increasing the initial Hg:Cd mole ratio spectral tuning was achieved. The size of the semiconductor nanocrystals was controlled between 8 nm to 44 nm by selecting the size of initial CdTe nanocrystals. Water dispersible Gd doped CdTe nanocrystals were also studied by changing initial Cd:Gd mole ratio. CdS shell was formed in order to make more compact and stable Gd doped CdTe nanocrystals. Size of Gd doped CdTe/CdS nanocrystals was tuned up to 38 nm by increasing initial Gd content. The optical spectra of Gd doped CdTe nanocrystals were in the range from 535 nm to 555 nm after 4 hours reaction time. Photoluminescence quantum efficiencies of Gd doped CdTe nanocrystals were measured and found out that doping Gd, decrease the quantum yield of nanocrystals. We concluded that CdTe nanocrystals can be used to synthesize doped nanocrystals by chemical doping. We demonstrated that optical and structural properties of Hg and Gd doped CdTe can be rendered by chemical doping.