Metallic nanoparticles (NPs) with various elemental composition, size, shape and physical or chemical properties has become active field of research. Among all the metal NPs noble metal ones are receiving much attention due to their special optical properties which make them useful for different applications. Noble metal NPs have bright colors resulting from strong surface plasmon resonance absorption usually in the visible region. The colors are size and shape dependent and provide the tuning of optical properties. The optical properties of NPs are also strongly depending on the nature of the NPs surface which plays a crucial role on chemical sensing. Therefore, surface modification of NPs has become increasingly important. In this study, gold NPs were prepared in aqueous phase by seed-mediated growth method. To enhance the optical properties, surface functionalization was performed by coating NPs with silver. The coating process was achieved by chemical reduction of silver ions on NPs surface. Thickness of silver layer on the NPs were attempted to be controlled by the amount of silver salt added into NPs solution. Coating process of different types of gold NPs (rod, octahedral, star) was done by the same procedure. Moreover, this attempt yielded control over silver layer thickness on sphere, rod and octahedral shaped gold NPs, but not on branched NPs. The structure, composition and spectroscopic properties of Au-Ag core shell NPs were characterized by UV-Vis spectroscopy, Field Emission Transmission Electron Microscope (FE-TEM) and Energy-dispersive X-ray (EDX) studies, Scanning Electron Microscope (SEM), and X-Ray Photoelectron Spectroscopy (XPS). The analysis showed that all NPs studied were successfully coated with silver and promising for further explorations in sensing and imaging applications.

In this study, a new gas turbine monitoring system being able to carry out appropriate run process is set up for a gas turbine with 250 kW power rating and its accessories. The system with the mechanical and electrical connections of the required sub-parts is transformed to a kind of the test stand. Performance test result calculation method is described. In addition that, performance evaluation software being able to apply with the completion of the preliminary performance tests is developed for this gas turbine. This system has infrastructure for the gas turbine sub-components performance and aerothermodynamics research. This system is also designed for aviation training facility as a training material for the gas turbine start and run demonstration. This system provides the preliminary gas turbine performance research requirements in the laboratory environment.

Benzoin is an important a-hydroxy ketone which can be used as chiral intermediate for the synthesis of several drugs. In this study, it was aimed to synthesize this compound by high stereoslectivity and yield by the use of fungal bioconversions. For this purpose, whole cells of four different Fusarium spp. (F. anguoides, F. roseum, F. solanii, F.bulbigenum) were used for reduction of readily available achiral compound benzil. The reaction conditions were optimized as glucose peptone broth consisting of 30g/L glucose and 10 g/L peptone, inoculum size as 20 mg/L and substrate concentration as 200 mg/L. A complete set of derivatives substituted with electron donating and electron withdrawing groups of the benzils were also reduced to the corresponding benzoin derivatives with the same optimized condition with up to 98% ee.

The objective of this study was to determine the effects of different gums, gum concentrations and their combination on quality and staling of gluten free cakes baked in microwave-infrared combination oven and conventional oven. In the first part of the study, the effects of different gums (xanthan and guar gum) at different concentrations (0.3%, 0.6% and 1.0%) and their blend on quality of gluten free cakes baked in microwave-infrared combination and conventional oven were investigated. The gelatinization properties of the cakes were also investigated. Among different gums, xanthan-guar gum blend addition to the cake formulation improved cake quality with increasing specific volume as well as decreasing weight loss and crumb hardness values for both types of baking methods. Gum blend addition also improved the cake acceptability in terms of texture, taste and the crust color of the cakes. The gelatinization degrees of cakes were found to decrease as the gum concentration increased, for both types of ovens. In the second part of the study it was focused on effects of different gums, gum concentrations and storage times on staling of cakes. Addition of gum blend decreased hardness, weight loss, retrogradation enthalpy and the change in setback viscosity values of cakes for both types of ovens and slowed down staling for 2 and 3 days for cakes baked in microwave-infrared combination and conventional oven, respectively. In microwave-infrared combination oven, it was possible to produce gluten-free cakes with similar quality with the conventionally baked ones even in a 75% shorter baking time.

The aim of this project was to design an intelligent controlled release system based on thermoresponsive nanoparticles for cancer therapy and to evaluate the efficiencies of these systems with in vitro cell culture. Poly(Nisopropylacrylamide), an important thermoresponsive polymer, was selected for this study to prepare the responsive nanoparticles. This polymer has an lower critical solution temperature (LCST) of 32 oC, below which it is hydrophilic and above this temperature, it shows hydrophobic behavior. Controlling drug release with this property was the objective of this study. Nanoparticles were prepared by nanoprecipitation method. By using different solvent:non-solvent ratios and polymer concentrations, different samples were prepared. The particle size was decreased when solvent:non-solvent ratio was increased and polymer concentration was decreased. This was found to be related with the solution viscosity. Nanoparticles prepared from polymers prepared with different initiatoraccelarator amounts had significantly different sizes and release rates, and additionally the size of particles prepared from polymers with various crosslinker amounts were decreased with increased croslinker amount. In situ release experiments were performed both below and above polymer&amp / #8216 / s LCST degree. Uncrosslinked nanoparticles demonstrated higher release rate of Celecoxib above LCST. However, there was no significant difference with the crosslinked nanoparticles. Crosslinked and uncrosslinked nanoparticles were tested on Saos-2 cells to assess their toxicity. Both Celecoxib loaded and free crosslinked particles were found to be cytotoxic. Uncrosslinked nanoparticles showed an increased toxicity upon loading with the bioactive agent, Celecoxib. In conclusion, uncrosslinked particles would be a proper drug carrier for cancer therapy with enhanced drug loading.

Photobiological hydrogen production from organic acids occurs in the presence of light and under anaerobic conditions. Stable and optimized operation of the photobioreactors is the most challenging task in the photofermentation process. The main aim of this study was to achieve in long term, a stable and high hydrogen production on acetate, using the photosynthetic bacteria Rhodobacter capsulatus in continuous panel photobioreactors. Rhodobacter capsulatus (DSM 1710), heat adapted Rhodobacter capsulatus (DSM 1710) and Rhodobacter capsulatus YO3 (Hup-), a mutant strain, were tested in outdoor conditions, under natural sunlight between September-December, 2008 in Ankara, Turkey. Defined culture medium containing acetate (40 mM) and glutamate (2 mM) and a dilution rate of 0.8 l/ day were used. Steady hydrogen production (0.4 mmol H2/lc.h) was obtained using the Rhodobacter capsulatus YO3 (Hup-) mutant strain that was continuously operated for 69 days, but the cell concentration could not be kept at a steady value. Further efforts were focused on achieving stable biomass concentration by optimizing the feed composition. Stable biomass (0.40 gdcw/lc) and high hydrogen productivity (0.8 mmol H2/lc.h) were achieved using feed media containing 40 mM acetate and 4 mM glutamate with a 10% (v/v) feed rate. Moreover, the EU project HYVOLUTION aims to combine dark fermentation and photofermentation process for the conversion of biomass to hydrogen. Effluents from the dark fementation contain high amount of ammonium, which inhibits phototrophic hydrogen production. After treatment it has been concluded that G&ouml / rdes clinoptilolite zeolite effectively removes ammonium ion from the dark fermenter effluent of molasses.

Scytalidium thermophilum is a termophilic fungus that effectively produces the extracellular enzyme catalase phenol oxidase (CATPO). The enzyme is distinct among catalases with its bifunctionality of oxidising phenolic compounds in the absence of H2O2. CATPO is capable of oxidizing catechol, chlorogenic acid, caffeic acid and catechin which are ortho &ndash / diphenolic compounds. Diphenolic compounds are known as strong antioxidants. Catalase is one of the important antioxidant enzymes. Therefore, in this thesis the effect of CATPO on the final antioxidant capacity of the oxidized products was analysed. Antioxidant capacity measurements of oxidized and unreacted phenolic compounds were done using the two widely used methods TEAC and FRAP. CATPO oxidized catechol showed 2.4 fold increase when compared to its nonoxidized form, which was highest among others. Catechol was followed by caffeic acid, chlorogenic acid, and catechin. This finding is new to the literature and may be of importance to the antioxidant mechanism of organisms. Results have also shown that the most well known phenol oxidases, laccase and tyrosinase, do not result in such high increases in antioxidant capacity upon oxidation of the substrates tested. Due to this finding, as a possible means of applying CATPO to increase the antioxidant capacity of products daily consumed, tea was selected. Tea is the second most consumed beverage after water and it is known to possess high amounts of flavanols. Green tea is rich in catechins whereas black tea is a rich source of theaflavins and thearubigins. Fermentation is a critical process for production of good quality tea and is the key step differing between green and black tea production. During this process phenol oxidases catalyze the oxidation of polyphenolic compounds present in tea leaves to their corresponding o-quinones. Utilization of CATPO in tea samples resulted in an increase in antioxidant capacity and its effect was enhanced by an increase in brewing time. Interestingly, the addition of sugar decreased antioxidant capacity. Laccase and tyrosinase were ineffective in increasing the antioxidant capacity of tea samples.

Methicillin Resistant Staphylococcus aureus (MRSA) is one of the most important threats of nosocomial infections in many regions of the world and Vancomycin Resistant Enterococcus (VRE) is an emerging pathogen that develops full resistance against third-generation glycopeptide antibiotics. Conventional methods for identification of MRSA and VRE generally depend on culturing, which requires incubation of biological samples at least 24-72 hours to get accurate results. These methods are time consuming and necessitate optical devices and experts for evaluation of the results. On the other hand, early diagnosis and initiation of appropriate treatment are necessary to decrease morbidity and mortality rates. Thus, new diagnostic systems are essential for rapid and accurate detection of biological analytes at the point of care. This study presents design, fabrication, and implementation of MEMS based micro electrochemical sensor (&micro / ECS) to detect the methicillin resistance in Staphylococcus aureus and vancomycin resistance in Enterococcus species. To the best of our knowledge, the developed sensor is the first &micro / ECS which utilizes on-chip reference (Ag), working (Au), and counter (Pt) electrodes together with a microchannel to detect MRSA and VRE. The characterization of the designed sensor was achieved analyzing the interactions of the buffer solutions and solvents with the electrodes and Parylene C film layer by using optical and electrochemical methods. Specific parts of genes that are indicators of antimicrobial resistances were used in order to detect the resistances with high selectivity and sensitivity. Thus, synthetic DNA and bacterial PCR product were used as target probes in redox marker based detection and enzyme based detection, respectively. In order to enhance the hybridization, folding structures of the capture probe were investigated by using mfold Web Server. In redox marker based detection, the hybridization of DNA was indirectly detected by using Hoechst 33258 as redox marker with differential pulse voltammetry. The cross reactivity of the tests were performed by using different target probes of femA genes of S. aureus and S. epidermis, which are the major genes detected in methicillin detection assays. Consequently, amplification of signal by using horseradish peroxidase and TMB/H2O2 as substrate was achieved in order to enhance detection sensitivity. The sensor could detect 0.01 nM 23-mer specific part of mecA gene with redox marker based detection and 10 times diluted PCR product with enzyme-based detection in about six hours including the steps of sample preparation from whole blood. This sensor with its compatibility to MEMS fabrication processes and IC technology has a promising potential for a hand-held device for POC through the integration of micropotentiostat.

Foam separation is a simple and economic method for separation of surface-active molecules such as proteins and enzymes from aqueous solutions. In this study, lactic acid broth, spent brewer&rsquo / s yeast extract and residual beer was used to investigate the applicability and efficiency of foam separation technique in partial purification of fermentation products and recovery of valuable components from industrial waste streams. The effects of the process variables initial feed concentration, air flow rate, foaming time, liquid pool height and temperature on separation performance were studied and optimum conditions for removal of proteins from lactic acid broth was determined. Highest enrichment (172.2) and separation ratio (314) with a high protein recovery (45.2 %) were obtained by foaming 200 ml of lactic acid broth with an initial feed concentration of 0.018 mg/ml at an air flow rate of 38.5 cm3/min. Selectivity of foam separation in protein purification, and its effect on protein structure was investigated in brewery wastes using SDS-PAGE and native PAGE, respectively.

In this study agriculturally important Pseudomonas spp. which may solubilize phosphate and Azotobacter chroococcum which can fix atmospheric nitrogen were grown on waste beer with 4 different concentrations and conditions for best growth were determined. Having potential of use as biofertilizers, they were put in the carrier material peat and survivals of them were observed for 3 months at three different temperatures. Biofertilizer can be defined as a substance which contains living microorganisms which, when applied to seed, plant surface, or soil, colonizes the rhizosphere or the interior of the plant and promotes growth by replacing soil nutrients or making nutrients more available or increasing plant access to nutrients. In order to benefit from the biofertilizers, viable and active microorganisms in high numbers must be present which requires high quality inoculants. The carrier substrate is a critical part of the product formulation and must be capable of supporting high numbers of the intended microbe(s). It was found that Pseudomonas spp. can solubilize phosphate. Furthermore, conditions for best growth for both bacteria were determined as 30 % of waste beer. Peat was found as an appropriate carrier due to preservation of viable cells for 3 months at 0 &ordm / C, 20 &ordm / C and 30 &ordm / C. However, peat couldn&rsquo / t support high numbers of Pseudomonas spp. at 30 &ordm / C.