Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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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; Eanes, Mehtap; Eanes, MehtapSingle 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, SerdarIn 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 Reactions of Oxomolybdenum Compounds With Nitrogen Donor Ligands and Related Computational Calculational Calculations(Izmir Institute of Technology, 2009) Öcal, Jale; Topaloğlu Sözüer, IşılReactions of the dioxomolybdenum(VI) compound, MoCl2O2 with phenylenediamine derivatives the bidentate N-N nitrogen ligands 1-8 (ophenylenediamine, N-phenyl-o-phenylenediamine, 4-Methyl-o-phenylenediamine, 4-Nitro-o-phenylenediamine, p-phenylenediamine, N-phenyl-p-phenylenediamine, 2,6- dichloro-p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, respectively) have been examined under nitrogen in THF solution. The novel dioxomolybdenum complexes were characterized by elemental analysis, FT-IR, 1H-NMR and 13C-NMR spectroscopy. In addition, molecular mechanics and quantum chemical calculations including semi empirical PM3 and DFT methods were carried out to discuss the stability of the compounds.Master Thesis Thermal and Photodehydrogenation Reactions of Terpenes Over Zeolites(Izmir Institute of Technology, 2003) Tuzcuoğlu, Esra; Artok, LeventIn this thesis study, catalytic activity of cation exchanged (Na+, Li+, Ca2+, K+, Cs+) zeolite Y, especially NaY, and various microporous and mesoporous (Na exchanged, Beta, Mordenite, and NaX, CsNaX, MCM-41, Montmorillonite KSF and amorphous Silica) catalysts was investigated in the dehydrogenation reaction of terpenes to p-cymene.The results suggested that, there are two types of acid sites are present in cation exchanged zeolites from NH4Y, which are Br Bronsted and Lewis sites. a-terpinene, disproportionated by Br Bronsted acid catalysis into 3-p-menthene and p-cymene, and pcymene was also formed by direct dehydrogenation of a-terpinene can possibly occur with the participation of Lewis acid sites in cation exchanged zeolite Y. Best conversion to p-cymene were observed in the NaHY, LiHY and CaHY exchange from NH4Y that have relatively small cations, which more acidic than the larger ones.With the catalysts that have Bronsted acid sites except ion-exchanged zeolite Y, no conversion or only acid catalyzed isomerization reactions occur that shows the Bronsted acidity was not enough to catalyze the dehydrogenation of a-terpinene. Also Lewis acidic character and the structure morphology are the most important factors affecting the conversion. Lewis acidity is influenced from the cation and zeolite type.Master Thesis A Proteomic Approach for Indentifying Boron-Stress Tolerant Proteins in Barley Genotpes(Izmir Institute of Technology, 2008) Atik, Ahmet Emin; Yalçın, TalatBoron is an essential micro-nutrient for plants. However, when boron is present at high concentrations in the soil or ground water, healthy plant growth and development can be affected by boron toxicity. Turkey constitutes about 72 % of the total boron reserves in the world. In Turkey, barley (Hordeum vulgare) is the second widely grown cereal after wheat. Boron toxicity is one of the major factors limiting the yield of barley in Central Anatolia of Turkey. In the present study, proteomic approach was used to investigate the boronstress tolerant proteins in Anadolu barley genotype (boron-tolerant). Eight-day-old barley plants were treated with 10 mM H3BO3 for seven days. Control plants received no boron treatment during this period. Total proteins of leaves were extracted and separated by two-dimensional polyacrylamide gel electrophoresis. Control and borontreated Anadolu genotype.s proteome maps were compared and the novel proteins were fragmented into peptides using in-gel digestion technique. Liquid chromatographytandem mass spectrometry (LC-MS/MS) analysis and database searching gave way to identify ten spots representing seven different proteins. Two spots were identified as the same protein and one protein could not identified. The identified seven proteins are namely, ribulose 1,5-bisphosphate carboxylase/oxygenase large chain (RuBisCo largechain), thaumatin-like protein TLP5, basic pathogenesis-related protein PR5, RNase Slikeprotein, vacuolar proton-translocating ATPase subunit E, PSI type III chlorophyll a/b-binding protein, and light-harvesting complex I; LHC I. Among the identified seven proteins, vacuolar proton-translocating ATPase (VATPase) subunit E is the important one for boron tolerance in tolerant barley genotype. It is shown that the accumulation of excess boron in the vacuolar compartment of the plant cell by the help of V-ATPase subunit E protein. This is the known as internal tolerance mechanisms for Anadolu genotype of barley to survive under boron stress. It was proposed that, this might be the defense mechanism in boron-tolerant barley genotype under toxic boron concentrations.Master Thesis Characterization of Ion Implanted Surfaces by Laser Induced Breakdown Spectroscopy, Libs(01. Izmir Institute of Technology, 2008) Örer, Sabiha; Yalçın, ŞerifeLaser Induced Breakdown Spectroscopy, LIBS, is a versatile atomic emission spectrometric technique for the determination of the elemental composition of solids, liquids, gases and aerosols with the need for little or no sample preparation.In this study, an optical LIBS system from its conventional parts was designed, constructed and optimized for spectrochemical analysis of solid materials. Specifically, the 2-D elemental distribution of Ge ions on silicon oxide surfaces, prepared by the method of ion implantation, with differing atomic concentrations between 1016 - 1017 ions/cm2 have been investigated by LIBS. For this purpose a Nd: YAG laser operating at the second harmonic wavelength, 532 nm, was used to create a plasma on the material surfaces. Spatially and temporally resolved atomic emission from the luminous plasma was detected by an Echelle spectroctrograph and Intensified Charged Coupled Device (ICCD) detector combination. Spectral emission intensity from the LIBS measurements has been optimized with respect to time, crater size, ablation depth and laser energy. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-Ray Spectroscopy (EDX) have been utilized to obtain crater depth, morphology and elemental composition of the sample material, respectively. LIBS spectral data revealed the possibility of performing 2-D distribution analysis of Ge ions over the silicon oxide substrate at Ge ion concentrations lower than 0.5% (atomic). LIBS as a fast semi-quantitative analysis method with 50.m lateral and 800 nm depth resolutions has been evaluated. In this wok, elemental analysis of some metal surfaces, such as Al and Cu, was also performed by LIBS.Keywords: LIBS, surface analysis, Ge ion implantation, lateral resolution,Master Thesis Prediction of Extractives and Lignin Contents of Anatolian Black Pine (pinus Nigra Arnold. Var Pallasiana) and Turkish Pine (pnus Brutia Ten.) Trees Using Infrared Spectroscopy and Multivariate Calibration(Izmir Institute of Technology, 2008) Karaman, İbrahim; Özdemir, Durmuş; Özdemir, DurmuşDetermination of quality parameters such as extractives and lignin contents of wood by wet chemistry analyses takes long time. Near-infrared (NIR) and mid-infrared (MIR) spectroscopy coupled with multivariate calibration offer fast and nondestructive alternative to obtain reliable results. However, due to complexity of multi-wavelength spectra, wavelength selection is generally required. Turkish pine and Anatolian black pine are the most growing pine species in Turkey. Forest products industry has widely accepted use of these trees because of their ability to grow on a wide range of sites and their suitability to produce desirable products. Determination of extractives and lignin contents of wood provides information to tree breeders when to cut and on how much chemical is needed in pulping and bleaching process. In this study, 58 samples of Turkish pine and 51 samples of Anatolian black pine were collected to investigate the correlation between NIR and MIR spectra of these samples and their extractives and lignin contents which were determined with reference methods. Genetic inverse least squares (GILS) was used for multivariate calibration. Standard error of calibration (SEC) values were less than 1.86% (w/w) for lignin and 1.19% (w/w) for extractives whereas standard error of prediction (SEP) values were less than 3.81% (w/w) for lignin and 2.04% (w/w) for extractives. Resulting R2 values for calibrations were larger than 0.8. Classification for Turkish pine and Anatolian black pine samples was performed by genetic algorithm based principal component analysis (GAPCA) and these two pine species were classified by using NIR and MIR spectra.Master Thesis Investigation of Heat Stress-Induced Proteins of Cold-Adapted Pseudomonas Marginals Using Proteomic Approach(Izmir Institute of Technology, 2008) Taşoğlu, Çağdaş; Yalçın, TalatTemperature alteration is known as a common environmental stress condition which all living organisms encounter and response by producing evolutionary wellconserved specific proteins called heat stress or heat shock proteins in the cell in order to adapt and survive. In the current study, the induction of heat stress proteins in a coldadapted bacterial strain of Pseudomonas marginalis cells grown under heat stress was investigated by proteomic approach. Five different temperatures, 5, 10, 15, 24, and 30C, were examined for the purpose of determining the optimum growth temperature for the bacterium. Consequently, 15°C was observed as optimum temperature for growth while 30C was established as heat stress temperature. Total proteins from Pseudomonas marginalis cells in the late exponential phase of growth at these two temperatures were extracted and separated by two-dimensional polyacrylamide gel electrophoresis. Totally 1391 protein spots were visualized for 15C and 1384 protein spots for 30C. After comparing with 15C, 13 protein spots that were differentially expressed in the cells exposed to heat stress (30C) were cut from the gel and fragmented into their peptides by in-gel digestion method. Finally, these proteins were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and database searching. Among them, ribosome recycling factor, universal stress protein family and chaperonin GroEL were established as direct sensors of heat stress. As a result, the genes encoding these two heat stress proteins can be isolated and cloned into any other useful microorganism such as bacteria used for detoxification of industrial waste or used in bioremediation but not capable of surviving at high temperatures so that they can be efficient at those temperatures, too.Master Thesis Characterization of the Adsorption Behaviour of Aqueous Cd (ii) and Ni (ii) Ions on Nanoparticles of Zero-Valent Iron(Izmir Institute of Technology, 2008) Efecan, Nazlı; Shahwan, Talal; Shahwan, TalalIron nanotechnology is recently concieved as a promising tool in environmental remediation. By virtue of their high surface/volume ratio, iron nanoparticles were shown to demonstrate outstanding sequestration capacity for various organic and inorganic pollutants.In this work iron nanoparticles were synthesized using the borohydride-reduction method. The obtained material showed chain like morphology, with the diameter of the nanoparticles being with in 20-80 nm range. HR-TEM images showed that the nanoparticles have a core-shell structure, with the core containing iron in its zero-valent state, while the shell is composed of iron oxides (Fe2O3, Fe3O4, FeOOH)and is generally < 3 nm in thickness.Nano-sized zero valent iron (nZVI) was then tested as a sorbent material for aqueous Cd2+ and Ni2+ ions. The uptake of these ions was investigated under various experimental conditions like time, concentration, pH, repititive application, and liquid/solid ratios. In addition, the uptake of these ions was compared with that of Cu2+, Zn2+, and Sr2+ in order to assess the effect of the reduction potential on the extent of removal.The results showed that nZVI is a very effective sorbent in terms of both kinetics and capacity of removal of the ions. Under the investigated conditions, the uptake reached equilibrium in less than one hour of contact time. Up to the initial concentration of 500 mg/L, the ions were removed almost completely utilizing an nZVI amount of 0.025 g and a solution volume of 10 ml. According to XRD and XPS results, both of Cd2+ and Ni2+ ions were fixed by nZVI through a non-reductive mechanism, that seems to be dominated by interaction of these ions with the exposed iron oxyhydroxide groups at the interface with the solution.Master Thesis Synthesis and Characterization of Mgb2 Superconducting Wires(Izmir Institute of Technology, 2008) Horzum Polat, Nesrin; Özgen, TamerkanIn this study, the superconducting properties of laboratory synthesized MgB2 was investigated. In the first part, MgB2 synthesis using commercial magnesium and boron (95-97% purity), and its microstructural and electrical characterization was investigated.Effects of sheath material and annealing temperatures were also examined. The microstructural studies showed that when Cu tubes were used as sheath material, MgCu2 forms instead of MgB2 even at 700oC, while on Fe clad cores, the major phase was MgB2 with minor MgO constituent. The transition temperatures of Fe clad wires were measured between 39K and 40K, whereas no transition temperature was observed for Cu clad wires. The Ic value of the Fe clad MgB2 wire was about 25 A at 4K, while the copper clad wire could not carry current and formed resistance. In Fe clad wires, better results were obtained at annealing temperature of 800°C for 30 minutes. In the second part, MgB2 synthesis using commercial magnesium and boron (90% purity) was tried. 0-5-10-15 wt% of Mg doping and, additionally annealing temperatures were examined. Powder-In-Tube method was used for wire production. 10 wt% Mg addition was seen to be beneficial as compared to the stoichiometric MgB2. 750°C was found to be the most suitable temperature for the formation of MgB2 phase. The Ic value of the wire was measured as 13 A at 4K and it showed a broader transition with non-zero resistivity, transition temperature of 24K.In the third part, 200 m long four filament MgB2/Cu wire was successfully produced in laboratory conditions.