This thesis summarizes the methods and major findings of Ni-W(P)/ã-Al2O3 nitride cata-lyst synthesis, characterization, hydrotreating activity, kinetic analysis and correlation of the catalysts activities to their synthesis parameters and properties.<p> The range of parameters for catalyst synthesis were W (15-40 wt%), Ni (0-8 wt%), P (0-5 wt%) and nitriding temperature (TN) (500-900 °C). Characterization techniques used included: N2 sorption studies, chemisorption, elemental analysis, temperature programmed studies, x-ray diffraction, scanning electron microscopy, energy dispersive x-ray, infrared spectroscopy, trans-mission electron microscopy and x-ray absorption near edge structure. Hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatization (HDA) were performed at: tem-perature (340-380 °C), pressure (6.2-9.0 MPa), liquid hourly space velocity (1-3 h-1) and hydro-gen to oil ratio (600 ml/ml, STP).<p> The predominant species on the catalyst surface were Ni3N, W2N and bimetallic Ni2W3N. The bimetallic Ni-W nitride species was more active than the individual activities of the Ni3N and W2N. P increased weak acid sites while nitriding temperature decreased amount of strong acid sites. Low nitriding temperature enhanced dispersion of metal particles. P interacted with Al2O3 which increased the dispersion of metal nitrides on the catalyst surface. HDN activity in-creased with Ni and P loading but decreased with increase in nitriding temperature (optimum conversion; 60 wt%). HDS and HDA activities went through a maximum with increase in the synthesis parameters (optimum conversions; 88. wt% for HDS and 47 wt% for HDA). Increase in W loading led to increase in catalyst activity. The catalysts were stable to deactivation and had the nitride structure conserved during hydrotreating in the presence of hydrogen sulfide.<p> The results showed good correlation between hydrotreating activities (HDS and HDN) and the catalyst nitrogen content, number of exposed active sites, catalyst particle size and BET surface area.<p> HDS and HDN kinetic analyses, using Langmuir-Hinshelwood models, gave activation energies of 66 and 32 kJ/mol, respectively. There were no diffusion limitations in the reaction process. Two active sites were involved in HDS reaction while one site was used for HDN. HDS and HDN activities of the Ni-W(P)/ã-Al2O3 nitride catalysts were comparable to the corre-sponding sulfides.

The objective of this dissertation is to shed light on the physical properties of InN epilayers grown by High-Pressure Chemical Vapor Deposition (HPCVD) for optical device applications. Physical properties of HPCVD grown InN layers were investigated by X-ray diffraction, Raman scattering, infrared reflection spectroscopies, and atomic force microscopy. The dependencies of physical properties as well as surface morphologies of InN layers grown either directly on sapphire substrates or on GaN/sapphire templates on varied growth conditions were studied. The effect of crucial growth parameters such as growth pressure, V/III molar ratio, precursor pulse separation, substrate material, and mass transport along the flow direction on the optical and structural properties, as well as on the surface morphologies were investigated separately. At present, growth of high-quality InN material by conventional growth techniques is limited due to low dissociation temperature of InN (~600 ºC) and large difference in the partial pressures of TMI and NH3 precursors. In this research, HPCVD technique, in which ambient nitrogen is injected into reaction zone at super-atmospheric growth pressures, was utilized to suppress surface dissociation of InN at high temperatures. At high pressures, long-range and short-range orderings indicate that c-lattice constant is shorter and E2(high) mode frequency is higher than those obtained from low-pressure growth techniques, revealing that InN structure compressed either due to a hydrostatic pressure during the growth or thermal contraction during the annealing. Although the influence of varied growth parameters usually exhibit consistent correlation between long-range and short-range crystalline orderings, inconsistent correlation of these indicate inclination of InN anisotropy. InN layers, grown directly on α-sapphire substrates, exhibit InN (1 0 1) Bragg reflex. This might be due to a high c/a ratio of sapphire-grown InN epilayers compared to that of GaN/sapphire-grown InN epilayers. Optical analysis indicates that free carrier concentration, ne, in the range of 1–50 × 1018 cm–3 exhibits consistent tendency with longitudinal-optic phonon. However, for high ne values, electrostatic forces dominate over inter-atomic forces, and consistent tendency between ne and LO phonon disappears. Structural results reveal that growth temperature increases ~6.6 ºC/bar and V/III ratio affects indium migration and/or evaporation. The growth temperature and V/III ratio of InN thin films are optimized at ~850 ºC and 2400 molar ratio, respectively. Although high in-plane strain and c/a ratio values are obtained for sapphire-grown epilayers, FWHM values of long-range and short-range orderings and free carrier concentration value are still lower than those of GaN/sapphire-grown epilayers. Finally, vibrational and optical properties of chalcopyrite ZGP crystal on the (001), (110), and (10) crystalline planes were investigated by Raman scattering and infrared (IR) reflection spectroscopies. Raman scattering exhibits a nonlinear polarizability on the c-plane, and a linear polarizability on the a- and b-planes of ZGP crystal. Also, birefringence of ZGP crystal was calculated from the hydrostatic pressure difference between (110) and (10) crystalline planes for mid-frequency B2(LO) mode.

The success of recent 3-D stereoscopic movies such as Avatar has created a lot of attention for 3-D in the home. Almost all major consumer electronics (CE) manufacturers have launched their 3-D stereoscopic displays in the market. A problem with those solutions is that viewers have to wear glasses. Glasses-free autostereoscopic 3-D displays typically use lenticular lenses or barriers to create multiple views. However these displays suffer from a number of issues: inverted views at viewing cone transitions, cross-talk between views, and need for multi-view content.  As Philips Electronics research group, we believe that some of these issues can be reduced by using pupil tracking. In the research process, we began with an extensive literature study on people detection and tracking techniques that helped us to understand the benefits and the shortcomings of different applications. Addition to literature studies, we greatly benefited from constant experimentation with prototypes and the hands-on experience with variety of digital and optical components under different conditions. As a result, we designed a multi-person infrared pupil tracker and multi-view renderer for 3D display to adapt the view rendering in real-time according to viewer’s position. Together with the integration of these two applications, the integrated 3D TV successfully adapts the center view according to position of the viewer and able to provide a smooth transition while the viewer actively changes her position from a notable distance under ambient illumination. However, even though the pupil tracker is implemented for multiple people, because of the time limitation and the complexity of the problem regarding multi-view renderer, the integrated system functions only for one person.   Exploring the employed technique, in-depth description and detailed illustration of designed applications and the conclusions drawn from the implemented system; we believe that this paper forms a substantial guidance and show-how source for further research in the field of 3D display and people tracking methods.

The goal of the project work has been to study the symmetry of the phonons in 4H and 6H-SiC for different measuring geometries by using two experimental techniques, Raman and infrared absorption (IR) spectroscopy, and a theoretical model. The Raman spectra were measured in different scattering configurations in order to obtain experimental data for detailed investigation of the phonon symmetries. The gross features of the spectra obtained in different geometries can be explained using general group-theoretical arguments. Using a lattice-dynamics model, we have also calculated the angular dependence of the phonon energies near the centre of the Brillouin zone, as well as the phonon displacements in some high-symmetry directions. The theoretical results are used to interpret the Raman lines in different configurations, and it was possible to estimate that if ionicity of the bonding of 12% is taken in the theoretical model for 4H-SiC, the splitting of the polar TO mode and the shift of the polar LO mode observed in our spectra are well reproduced theoretically. It was also observed that these polar modes have to be classified as longitudinal and transversal with respect to the direction of phonon wave vector, while the rest of the modes remain longitudinal or transversal with respect to the c-axis of the crystal. The Raman lines in the case of 4H SiC have been tentatively labelled with the irreducible representations of the point group of the crystal (C6v).

Cycling of the relative humidity (RH) levels in the reactant streams of polymer electrolyte membrane (PEM) fuel cells has been reported to decay fuel cell performance. This study focuses on the accelerated durability testing to examine different modes of membrane failure via RH cycling. A single PEM fuel cell with an active area of 42.25 cm2 was tested. A Greenlight G50 test station was used to establish baseline cell (Run 1) performance with 840 hours of degradation under high-humidity idle conditions at a constant current density of 10 mA cm-2. Under the same conditions, two other experiments were conducted by varying the RH. For the H2-air RH cycling test (Run 2), anode and cathode inlet gases were provided as dry and humidified gases. Another RH cycling experiment was the H2 RH cycling test (Run 3): the anode inlet gas was cycled whereas keeping the other side constantly at full humidification. These two RH cycling experiments were alternated in dry and 100% humidified conditions every 10 and 40 minutes, respectively. In the experiments, the fuel cells contained a GoreTM 57 catalyst coated membrane (CCM) and 35 BC SGL gas diffusion layers (GDLs). The fuel cell test station had been performed under idle conditions at a constant current density of 10 mA cm-2. Under the idle conditions, operating at very low current density, a low chemical degradation rate and minimal electrical load stress were anticipated. However, the membrane was expected to degrade due to additional stress from the membrane swelling/contraction cycle controlled by the RH. In this work the performance of the 100% RH humidified cell (Run 1) was compared with that of RH cycling cells (Run 2 and Run 3). Chemical and mechanical degradation of the membrane were investigated using in-situ and ex-situ diagnostic methods. The results of each measurement during and after fuel cell operation are consistent. They clearly show that changing in RH lead to an overall PEM fuel cell degradation due to the increase in membrane degradation rate from membrane resistance, fluoride ion release concentration, hydrogen crossover current, membrane thinning, and hot-spot/pin-hole formation.

This thesis summarizes the methods and major findings of Ni-W(P)/ã-Al2O3 nitride cata-lyst synthesis, characterization, hydrotreating activity, kinetic analysis and correlation of the catalysts activities to their synthesis parameters and properties.<p> The range of parameters for catalyst synthesis were W (15-40 wt%), Ni (0-8 wt%), P (0-5 wt%) and nitriding temperature (TN) (500-900 °C). Characterization techniques used included: N2 sorption studies, chemisorption, elemental analysis, temperature programmed studies, x-ray diffraction, scanning electron microscopy, energy dispersive x-ray, infrared spectroscopy, trans-mission electron microscopy and x-ray absorption near edge structure. Hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatization (HDA) were performed at: tem-perature (340-380 °C), pressure (6.2-9.0 MPa), liquid hourly space velocity (1-3 h-1) and hydro-gen to oil ratio (600 ml/ml, STP).<p> The predominant species on the catalyst surface were Ni3N, W2N and bimetallic Ni2W3N. The bimetallic Ni-W nitride species was more active than the individual activities of the Ni3N and W2N. P increased weak acid sites while nitriding temperature decreased amount of strong acid sites. Low nitriding temperature enhanced dispersion of metal particles. P interacted with Al2O3 which increased the dispersion of metal nitrides on the catalyst surface. HDN activity in-creased with Ni and P loading but decreased with increase in nitriding temperature (optimum conversion; 60 wt%). HDS and HDA activities went through a maximum with increase in the synthesis parameters (optimum conversions; 88. wt% for HDS and 47 wt% for HDA). Increase in W loading led to increase in catalyst activity. The catalysts were stable to deactivation and had the nitride structure conserved during hydrotreating in the presence of hydrogen sulfide.<p> The results showed good correlation between hydrotreating activities (HDS and HDN) and the catalyst nitrogen content, number of exposed active sites, catalyst particle size and BET surface area.<p> HDS and HDN kinetic analyses, using Langmuir-Hinshelwood models, gave activation energies of 66 and 32 kJ/mol, respectively. There were no diffusion limitations in the reaction process. Two active sites were involved in HDS reaction while one site was used for HDN. HDS and HDN activities of the Ni-W(P)/ã-Al2O3 nitride catalysts were comparable to the corre-sponding sulfides.

The research described in this thesis contributes to the development of new strategies facilitating advanced understanding of the fundamental principles governing selective recognition of molecularly imprinted polymers (MIPs) at a molecular level for the rational optimization of biomimetic materials. The nature of non-covalent interactions involved in the templating process of molecularly imprinted polymers based on the self-assembly approach were investigated with a variety of analytical techniques addressing molecular level interactions. For this purpose, the concerted application of IR and 1H-NMR spectroscopy enabled studying the complexation of the template molecules 2,4-dichlorophenoxyacetic acid, quercetin, and o-, m-, and p-nitrophenol with a variety of functional monomers in the pre-polymerization solution by systematically varying the ratio of the involved components. In aqueous and non protic porogenic solvents, information on the interaction types, thermodynamics, and complex stoichiometry was applied toward predicting the optimum imprinting building blocks and ratios. Molecular dynamics simulations of 2,4-dichlorophenoxyacetic acid and its interactions with the functional monomer 4-vinylpyridine in aqueous and aprotic explicit solvent allowed demonstrating the fundamental potential of computer MD simulations for predicting optimized pre-polymerization ratios and the involved interaction types. The obtained results clearly demonstrate that the application of rapid IR/NMR pre-screening methods in combination with molecular modeling strategies is a promising strategy towards optimized imprinting protocols in lieu of the conventionally applied labor intensive and time-consuming trial-and-error approach. Furthermore, HPLC characterization of the produced MIPs compared to control polymers enabled a systematic approach to imprinting based on advanced understanding of the factors governing the formation of high-affinity binding sites during the polymerization. In addition, the importance of the combination of size, shape, and molecular functionalities for the selective recognition properties of MIPs was investigated. MIPs for the mycotoxins deoxynivalenol and zearalenone and for the antioxidant quercetin were applied as separation materials for advanced sample preparation in beverage analysis. The obtained results demonstrated the potential of MIPs for rapid one-step sample clean-up and pre-concentration from beverages such as wine and beer.

The development of new storage materials will facilitate the use of hydrogen as a major energy carrier in near future. Among the chemical hydrides used as hydrogen storage materials for supplying hydrogen at ambient temperature, sodium borohydride seems to be an ideal one because it is stable under ordinary conditions and liberates hydrogen gas in a safe and controllable way in aqueous solutions. However, self hydrolysis of sodium borohydride is so slow that requires a suitable catalyst. This work aims the use of water dispersible cobalt(0) nanoclusters having large portion of atoms on the surface as catalyst for the hydrolysis of sodium borohydride. In-situ formation of cobalt(0) nanoclusters and catalytic hydrolysis of sodium borohydride were performed starting with a cobalt(II) chloride as precursor and sodium borohydride as reducing agent and substrate in the presence of a water soluble stabilizer. As stabilizer, water soluble polyacrylic acid as well as hydrogen phosphate ion were tested. Cobalt(0) nanoclusters were characterized by using all the available analytical methods including FT-IR, TEM, XPS, UV-visible electronic absorption spectroscopy. The kinetics of cobalt(0) nanoclusters catalyzed hydrolysis of sodium borohydride were studied depending on the catalyst concentration, substrate concentration, stabilizing agent concentration and temperature.

The in-situ examination of historical structures for diagnostic and monitoring purposes is a troublesome work that necessitates the use of non-destructive investigation (NDT) techniques. The methods of quantitative infrared thermography (QIRT) and ultrasonic testing have distinct importance in this regard. The key concern of the study was developing the in-situ use of QIRT for assessment of stone masonry wall sections having different sublayer(s) and failures. For that purpose, the non-destructive in-situ survey composed of QIRT and ultrasonic testing was conducted on a 16th century monument, Cenabi Ahmet PaSa Camisi, suffering from structural cracks, dampness problems and materials deterioration. The combined use of these two methods allowed to define the thermal inertia characteristics of structural cracks in relation to their depth. The temperature evolution in time during the controlled heating and cooling process was deployed for the cracks/defects inspection. The superficial and deep cracks were found to have different thermal responses to exposed conditions which made them easily distinguishable by QIRT analyses. The depth of cracks was precisely estimated by the in-situ ultrasonic testing data taken in the indirect transmission mode. The inherently good thermal resistivity of the wall structure was found to have failed due to entrapped moisture resulting from incompatible recent plaster repairs. The IRT survey allowed to detect the wall surfaces with different sublayer configurations due to their different thermal inertia characteristics. The knowledge and experience gained on the experimental set-ups and analytic methods were useful for the improvement of in-situ applications of QIRT and ultrasonic testing.

Tyrosyl radicals can facilitate proton-coupled electron transfer (PCET) reactions that are linked to catalysis in many biological systems. One such protein system is ribonucleotide reductase (RNR). This enzyme is responsible for the conversion of ribonucleotides to deoxyribonucleotides. The beta2 subunit of class Ia RNRs contains a diiron cluster and a stable tyrosyl radical (Y122*). Reduction of ribonucleotides is dependent on reversible, long-distance PCET reactions involving Y122* located 35 Å from the active site. Protein conformational dynamics are postulated to precede diiron cluster assembly and PCET reactions in RNR. Using UV resonance Raman spectroscopy, we identified structural changes to histidine, tyrosine, and tryptophan residues with metal cluster assembly in beta2. With a reaction-induced infrared spectroscopic technique, local amide bond structural changes, which are associated with the reduction of Y122*, were observed. Moreover, infrared spectroscopy of tyrosine-containing pentapeptide model compounds supported the hypothesis that local amide bonds are perturbed with tyrosyl radical formation. These findings demonstrate the importance of the amino acid primary sequence and amide bonds on tyrosyl radical redox changes. We also investigated the function of a unique tyrosine-histidine cross-link, which is found in the active site of cytochrome c oxidase (CcO). Spectrophotometric titrations of model compounds that mimic the cross-link were consistent with a proton transfer role in CcO. Infrared spectroscopic data support the formation of tyrosyl radicals in these model compounds. Collectively, the effect of the local structure and the corresponding protein dynamics involved in tyrosyl radical-mediated PCET reactions are illustrated in this work.