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Synthesis of copper nanoparticles by a colloidal recipe in a two-phase liquid-liquid mixture (toluene/water) was investigated. The synthesis recipe used in this work was originally applied for the fabrication of alkylamine-capped gold nanoparticles. This method involves transferring metal cations from the aqueous layer to the organic one by the phase transfer reagent, tetraoctylammonium bromide, followed by reduction with sodium borohydride in the presence of oleylamine, which was used as the stabilising ligand. Several modifications were made to the original recipe to produce copper nanoparticles with high degrees of purity and stability. These particles are potentially applicable in various industries and are considered as an alternative for expensive metal nanoparticles, such as gold, silver, and platinum. Due to the high tendency of copper for oxidation, all of the synthesis experiments were carried out in a glove box under the flow of an inert gas (N2 or Ar). The concentration of Cl− was initially increased to form anionic complexes of copper that could later react with the cationic phase transfer reagent. This modification was followed to enhance the efficiency of the transferring step; however, the presence of anion, Cl−, at the surface of the synthesized particles was reported to change their properties; thus, increasing chloride concentration was eventually ignored. The decanting of two phases prior to the reduction step was also investigated to examine whether the site of the reduction reaction could be limited to cores of reverse micelles. The aggregated nanoparticles, which were fabricated by reducing the decanted organic phase, were heated after the synthesis at 150°C for 30 minutes to obtain a light green solution of nanoparticles. However, further characterization was not possible due to the hydrocarbon impurities. Dodecane, which was employed as the solvent for post-synthesis heating procedure, is believed to result in these impurities. Further investigation is required to explain the mechanism by which post-synthesis heating facilitates nanoparticle stabilization. Duplication of the original recipe for copper in an inert atmosphere resulted in a mixture of assembled layers of separated copper nanocrystals with an average size of ~ 5 nm and aggregated clusters of cubic copper (I) oxide nanoparticles. The possible mechanism for this division is believed to be the presence of the phase transfer reagent capped to the surface of a portion of synthesized particles leading to their metastability.

Synthesis of copper nanoparticles by a colloidal recipe in a two-phase liquid-liquid mixture (toluene/water) was investigated. The synthesis recipe used in this work was originally applied for the fabrication of alkylamine-capped gold nanoparticles. This method involves transferring metal cations from the aqueous layer to the organic one by the phase transfer reagent, tetraoctylammonium bromide, followed by reduction with sodium borohydride in the presence of oleylamine, which was used as the stabilising ligand. Several modifications were made to the original recipe to produce copper nanoparticles with high degrees of purity and stability. These particles are potentially applicable in various industries and are considered as an alternative for expensive metal nanoparticles, such as gold, silver, and platinum. Due to the high tendency of copper for oxidation, all of the synthesis experiments were carried out in a glove box under the flow of an inert gas (N2 or Ar). The concentration of Cl− was initially increased to form anionic complexes of copper that could later react with the cationic phase transfer reagent. This modification was followed to enhance the efficiency of the transferring step; however, the presence of anion, Cl−, at the surface of the synthesized particles was reported to change their properties; thus, increasing chloride concentration was eventually ignored. The decanting of two phases prior to the reduction step was also investigated to examine whether the site of the reduction reaction could be limited to cores of reverse micelles. The aggregated nanoparticles, which were fabricated by reducing the decanted organic phase, were heated after the synthesis at 150°C for 30 minutes to obtain a light green solution of nanoparticles. However, further characterization was not possible due to the hydrocarbon impurities. Dodecane, which was employed as the solvent for post-synthesis heating procedure, is believed to result in these impurities. Further investigation is required to explain the mechanism by which post-synthesis heating facilitates nanoparticle stabilization. Duplication of the original recipe for copper in an inert atmosphere resulted in a mixture of assembled layers of separated copper nanocrystals with an average size of ~ 5 nm and aggregated clusters of cubic copper (I) oxide nanoparticles. The possible mechanism for this division is believed to be the presence of the phase transfer reagent capped to the surface of a portion of synthesized particles leading to their metastability.

Lithium tetraborate (Li2B4O7) has aroused interest of scientists since 1960s by the courtesy of the thermoluminescence (TL) property it possesses. Over and above, it found widespread use in surface acoustic wave apparatuses, in sensor sector and in laser technology due to its non linear optical characteristics. For the uses in thermoluminescence dosimetry lithium tetraborate is activated by addition of a variety of metals as dopants. This study comprises the synthesis of lithium tetraborate by two methods (high temperature solid state synthesis and water/solution assisted synthesis) as well as doping and characterization of the material. Lithium tetraborate is readily commercially available in TL dosimetry / hence, the main aim is to specify practical production conditions to pioneer domestic production. In high temperature synthesis, the initial heating was performed at 400oC for 3 hours. Then the samples were heated at 750oC for two hours, intermittently mixed to enhance diffusion and exposed to the same temperature for another two hours. In water/solution assisted synthesis, stoichiometric quantities of reactants were mixed in water by heating and agitating in order to achieve homogenous mixing and good dispersion of the material. The remnant of water was removed from the system by 3 hours initial heating at 150oC. The synthesis stage is followed by doping step where the metals Cu, Ag and In in different proportions were doped in lithium tetraborate by solid state and solution assisted synthesis techniques. Powder X-ray diffraction method was employed for the characterization of the material. The thermal properties of doped and un-doped materials were studied by DTA (Differential Thermal Analyses). Besides, FT-IR (Fourier Transform Infra red) spectrometry analyses were performed in order to detect differences in the bond structure caused by doping The XRD patterns obtained showed that lithium tetraborate production was successful by both high temperature solid state synthesis and solution assisted synthesis Moreover, it was inferred from the XRD results that addition of dopants did not have a sound effect on the crystal structure. Furthermore, the DTA results displayed that addition of different dopants to the structure of lithium tetraborate did not cause any noticeable difference. The extensive TL measurements showed that the TL response of the material produced is affected by production and doping methods.

In this study, differences in glow curves of Mn doped LTB powder samples synthesized with solid and wet synthesis methods and doped by using solid and wet doping techniques were investigated. Firstly, LTB was synthesized by using wet synthesis method which mainly comprises dissolution of reactants in water as solvent. Second way to produce LTB which was used in this study was solid synthesis method. In solid synthesis method, reactants were mixed in powder form. In the second part of the study, LTB produced by two different methods were doped with Mn and additionally Ag, Mg or P by using two different doping techniques. In order to see structural differences between differently synthesized and differently doped LTB samples which contained different amount of dopant powder X-Ray Diffraction (XRD) method was employed. Besides, FTIR (Fourier Transform Infrared) spectroscopy analyses were performed in order to detect differences in the bond structure caused by doping. Additionally, Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) was used to determine the actual amount of dopant in LTB. Also morphological structures of samples were compared by using Scanning Electron Microscopy (SEM). Thermoluminescence measurements were performed with (TLD) Thermoluminescence Dosimeter equipment. XRD and FTIR analysis showed that syntheses of products were done in well success. Addition of dopants did not cause any changes in structural or bonding properties of LTB. It was possible to observe that, synthesis and doping methods and dopant concentration effect the thermoluminescence glow curves of doped LTB.

Strontium pyrophosphate is a promising phosphate that is used widely in the industry as a result of its luminescent, fluorescent, dielectric, semi-conductor, catalyst, magnetic and ion exchange properties. Thermoluminescent dosimetry (TLD) is one of such areas. Recent researches in METU on thermoluminescence property of strontium pyrophosphate showed that strontium pyrophosphate could give enough intensity for radiation dosimetry when doped with oxides of some rare-earth elements. In this study strontium pyrophosphate was synthesized and the product was doped with copper-silver, copper-indium and manganese-praseodymium ions by solid-state reaction. In addition to these processes, characterization and the investigation of thermoluminescence properties of strontium pyrophosphate with and without dopants was conducted. Stoichiometric quantities of strontium carbonate and ammonium dihydrogen phosphate were weighed, mixed and ground by agate mortar. Afterwards, the mixture was heated at 900&amp / #730 / C for 14.5 hours. For doping process, synthesized strontium pyrophosphate and different amounts of copper oxide, indium oxide, silver nitrate, manganese oxide and praseodymium oxide were weighed and powdered together. Then, mixture was heated at 950&amp / #730 / C for 11 hours. For characterization of strontium pyrophosphate samples with and without dopants / X-ray Diffraction (XRD) was implemented. Fourier Transform Infrared Spectroscopy (FTIR) was used to determine whether the bond structures were affected from doping or not. Thermal properties of the samples were investigated with the help of Differential Thermal Analysis (DTA). Morphology of compounds was observed by Scanning Electron Microscope (SEM). Afterwards thermoluminescence (TLD) studies were carried out. XRD pattern of samples showed that the intensity of hkl-310 peak of strontium pyrophosphate increased with the inclusion of metal oxides, however none of the characteristic peaks of metal oxides was observed. Addition of metal oxides caused no change in FTIR meaning that the anionic part of matrix compound, which is strontium pyrophosphate, has structural stability. Thermal analysis and morphological investigation of this material were performed. TLD results were different for each sample, which has different content. The most significant peak, which is suitable for radiation dosimetry was observed at 160&amp / #730 / C in the glow curve with the sample doped with 7% manganese oxide and 1% praseodymium oxide.

The purpose of this thesis was to design controllers by using H1 and &sup1 / control strategies in order to suppress the free and forced vibrations of smart structures. The smart structures analyzed in this study were the smart beam and the smart &macr / n. They were aluminum passive structures with surface bonded PZT (Lead-Zirconate-Titanate) patches. The structures were considered in clamped-free con&macr / guration. The &macr / rst part of this study focused on the identi&macr / cation of nominal system models of the smart structures from the experimental data. For the experimentally identi&macr / ed models the robust controllers were designed by using H1 and &sup1 / -synthesis strategies. In the second part, the controller implementation was carried out for the suppression of free and forced vibrations of the smart structures. Within the framework of this study, a Smart Structures Laboratory was established in the Aerospace Engineering Department of METU. The controller implementations were carried out by considering two di&reg / erent experimental set-ups. In the &macr / rst set-up the controller designs were based on the strain measurements. In the second approach, the displacement measurements, which were acquired through laser displacement sensor, were considered in the controller design. The &macr / rst two &deg / exural modes of the smart beam were successfully controlled by using H1 method. The vibrations of the &macr / rst two &deg / exural and &macr / rst torsional modes of the smart &macr / n were suppressed through the &sup1 / -synthesis. Satisfactory attenuation levels were achieved for both strain measurement and displacement measurement applications.

Les cyanoglucosides non-cyanogènes se trouvent dans de nombreuses plantes en particulier médicinales, mais n'ont été qu'assez peu étudiés. En particulier la Ménisdaurine, dont la synthèse n'a jamais été réalisée, nous a paru un objectif intéressant. Le produit de départ, choisi en fonction de travaux antérieurs, est un dérivé de la 7-oxanorbornanone. La première voie étudiée avait comme étape-clé l'addition électrophile sur une double liaison mais n'a pas abouti. Nous avons ensuite envisagé l'ouverture d'un époxyde suivie de réduction. Ayant observé que le cycle époxy peut être ouvert par migration intramoléculaire d'un groupement méthoxy en présence d'iode, nous avons réalisé la même réaction avec un groupement phenylthio. L'ouverture de l'époxyde a ainsi été effectuée de façon totalement régio- et stéréo-sélective dans des conditions pratiquement neutres, ce qui n'avait jusque là pas été rapporté dans la littérature. Une étude mécanistique a confirmé que cette réaction se déroulait bien en deux étapes : formation d'un hémimercaptal sur la fonction cétone suivie d'une ouverture de l'époxyde par attaque exclusivement intramoléculaire. Le remplacement de l'iode par l'iodure de zinc conduit à des rendements encore supérieurs. Le groupement phenylthio étant facilement enlevé par réduction, cette voie est très efficace pour réduire sélectivement un époxyde en alcool. La suite de la synthèse conduit à l'aglycone protégée souhaitée puis la glycosidation a été réalisée avec un rendement de 80%. La(-)-Ménisdaurine naturelle a été obtenue (et caractérisée sous forme de son pentaacétate) en 10 étapes et 3% de rendement global. / Non-cyanogenic cyanoglucosides are found in many plants, specially in medicinal species but have been the subject of only few studies. Particularly, Menisdaurin seemed us an interesting target and we decided to work on its first total synthesis. The starting material, chosen by reference to previous work in the laboratory, is a derivative of 7- oxanorbornanone. The first synthetic route had as key-step an electrophilic addition on a double bond but, unfortunately, was unsuccessful. Then we chose as an alternative the nucleophilic opening of an epoxide ring followed by reduction. We noticed that this epoxide ring could be opened by the intramolecular migration of a methoxy group in the presence of iodine, and therefore we tried, successfully, to perform the same reaction with a phenylthio group. So the opening of the epoxide ring was carried out with total regio- and stereo-selectivity in almost neutral conditions, which had not been hitherto reported in literature. Mechanistic studies confirmed that this reaction consisted of two steps : the formation of an hemimercaptal on the ketone followed by the opening of the epoxide by an intramolecular attack. Replacement of iodine by zinc iodide afforded even better yields. The phenylthio group being easily removed by reduction, this procedure is very efficient to obtain selectively an alcohol from an epoxide. Then, the following synthetic steps afforded the desired protected aglycone which was glycosidated with a 80% yield. Natural (-)­-Menisdaurin was obtained (and characterized as its pentaacetate) in 10 steps with a global 3% yield.

The main automotive catalytic media, precious metal-doped ceria-zirconia oxides, fundamental system character is unknown. Understanding the catalytic system properties should allow for the production of an optimal model catalyst. This goal of this study is to gain understanding of ceria-zirconia-palladium systems and to determine a reproducible method for preparing catalysts with minimal surface-carbon. This study investigates ceria-zirconia-palladium catalyst preparation via aqueous chemistry methods and a sputter deposition technique for doping ceria-zirconia oxide mixtures. Prepared catalysts are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XPS allows the surface species, after catalyst doping and annealing, to be evaluated. Prepared catalyst EM analysis allows for surface morphology and particle characteristic evaluation. Prepared catalysts are exposed to UHV conditions, palladium sputtered-coated, and annealed at various temperatures. Temperature dependency is observed in both percentage of carbon, metal, and oxygen species present. This study led to a reproducible, low-carbon content, doping method for use in future pollutant reaction studies.

Magister Scientiae - MSc (Physics) / Zinc oxide (ZnO) is a wide and direct semiconductor with a wurtzite crystal structure. Its multifunctionality as the ideal candidate in applications such as blue-UV light emitting diodes, transparent conducting oxide, selective gas sensor and efficient catalyst support among others, has attracted a significant interest worldwide. Nano-scaled ZnO has been synthesized in a plethora of shapes. A rich variety of physical and chemical methodologies have been used in the synthesis of undoped or doped ZnO. However, such methods either necessitate relatively high vacuum infrastructures, elevated temperatures, or the use of toxic reagents. The "green chemistry" synthesis of metal oxide nanoparticles which is based on using natural plant extract as an effective 'reducing agent' of metal precursor, has been reported to be a cleaner and environment-friendly alternative to the physical and chemical methods. The thesis is based on the synthesis and the main physical properties of pure ZnO nanoparticles synthesized by a completely green chemistry process using the natural extract of Aspalathus Linearis to bio-reduce the zinc acetate precursor. The obtained ZnO nanopowdered samples were annealed at different temperatures from 300 °C to 600 °C. The samples were characterized using Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Transmission Electron Microscopy, X-ray Diffraction, Differential Scanning Calorimetry, Thermogravimetric Analysis and Fourier Transform Infrared. Highly pure quasi-spherical ZnO nanoparticles with an average crystallite size of 24.6 nm (at 300 °C), 27.2 nm (at 400 °C), 27.6 nm (at 500 °C), and 28.5 nm (at 600 °C) were found. The results also showed that the average crystallite size increased with an increase in annealing temperature. It was successfully demonstrated that the natural plant extract of Aspalathus Linearis can be used in the bio-reduction of zinc acetate dihydrate to prepare highly pure ZnO nanoparticles.