Hybrid waveguides based on antiresonant reflecting optical waveguide (ARROW) structure on Si substrates is investigated. The core layer of the waveguide is separated from the Si substrate by interference cladding which consists of a high index first cladding layer and a low index second cladding layer. The Ta2O5 first cladding layer was grown by rf magnetron sputtering system. The SiON second cladding layer was deposited by plasma-enhanced chemical vapor deposition (PECVD) based on the reaction of SiH4/N2O mixtures. Typical propagation losses of the waveguides using this SiON material system are less than 0.15 dB/cm. The high quality cladding layers are prepared to form the Fabry-Perot cavities to ensure low loss operation of the ARROW device at antiresonant conditions. Two methods were proposed to demonstrate the enormous applications of hybrid ARROW waveguides. First, polyimide/Ta2O5/SiON ARROWs were fabricated to achieve high extinction ratio waveguide polarizers. This is accomplished by tuning the operating point of the TM0 mode from antiresonant condition toward high-order antiresonance of the second cladding layer utilizing birefringence of the waveguide core. The measured extinction ratio and insertion loss of a 2-cm-long ARROW polarizer are 40 dB and 2.2 dB, respectively. In addition, the temperature dependence of refractive index of organic-inorganic sol-gel glasses was measured by Mach-Zehnder interferometry using the ARROW waveguides. The Sol-gel/Ta2O5/SiO2 ARROWs were fabricated to characterize index-to-temperature coefficients (dn/dT) of the sol-gel glasses because the optical confinement factor of the ARROW is very close to 1. The measured index-to-temperature coefficients of the sol-gel glasses with different compositions are negative and are on the order of 10-4.

The unsaturated polyester/silica hybrids have been synthesized via sol-gel process and characterized in an effort to obtain a transparent hybrid material in this study, with emphasis on the effects of silica precursors and coupling agents. Chemical properties, thermal properties, and morphology of the hybrids were investigated by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results showed that silica particles can be dispersed homogeneously in the UP matrix; also, physical and chemical interactions at the interface between UP and silica can be enhanced by adding coupling agents into the system. From the thermal and chemical properties measurement, the decomposition temperature of UP backbone and the heat distortion temperature (HDT) of UP/Silica hybrid were higher than pure UP. Solvent-resistance of UP/Silica hybrid was also enhanced by adding coupling agents. A model illustrating the chemical and physical interaction at the interface due to the addition of coupling agents is proposed to explain the resulted obtained.

Oligomers of hard and soft segments of unsaturated polyesters (UP) were synthesized. They were blended in different ratios and cured with various amounts of styrene. Based on the criteria of tensile strength and strain, hard segment/soft segment (60/40 wt %) UPs containing 35 wt % and 45 wt % of extra amount of styrene were chosen for further studies. Inorganic-organic hybrid materials were prepared by incorporating tetraethoxysilane and poly(dimethylsiloxane) into the UP resins via the sol-gel process by changing the ratios of HCl/TEOS, H2O/TEOS, TEOS/PDMS and the reaction time. The specimens of these hybrid materials after curing were characterized using the tensile tester, rheometer, scanning electron microscope (SEM), 29Si-NMR and thermogravimeter. In the condition of HCl/TEOS molar ratio 0.07, H2O/TEOS molar ratio 4, TEOS/PDMS weight ratio 90/10 and the reaction time 3 hours, the results of 29Si-NMR, SEM and silicone mapping indicate that these silica gels with 3D network were well dispersed in the UP resins. These specimens had tensile strength of 512¡Ó16 kgf/cm2 and elongation of 11¡Ó4 % which are above the criteria of inhibitors. From the erosion testing, flame retardants was added unsaturated polyester and inorganic-organic hybrid materials that can help to resist heat flame, remain of a fire on the surface had the char forming.

ZnO (Zinc-oxide) is a wide bandgap (Eg~3.3 ev ) semiconductor material , it is transparent in the visible region of the spectra and therefore, also less light sensitive. ZnO-based TFT can increase the field mobility, improve the opening of AMLCD pixel and the problem of photo-excited leakage current. Here we demonstrate ZnO-based TFT which was fabricated by sol-gel material through spin-coating deposition method. The process of spin-costing deposition provides a more efficient way for depositing device components and low cost than vacuum techniques. In the experiment we controlled the conductive and carrier concentration by different annealing temperature and different annealing equipment for optimizing our device characteristic. The material analysis of ZnO film is discussed by FTIR, SEM, and n&k. The electrical characteristic was measured by the I-V measurement system.

The Mg-modified lead titanate [(Pb1-xMgx)TiO3,abbreviated to PMT] thin films were deposited on Pt/SiO2/Si substrates by spin coating with sol-gel processing in this thesis. 1,3 propanediol was used as solvent to minimize the number of cycles of spin coating and drying processes to obtain the desired thickness of thin film. By changing the Mg content (0~10 mol%) and the heating temperature (500~800¢J), the effects of various processing parameters on the thin films growth are studied. The effects of various Mg contents on the response of pyroelectric IR detector devices are studied also. Experimental results reveal that the Mg contents will influence strongly on grain size, dielectricity, ferroelectricity and pyroelectricity of PMT thin films. With the increase of Mg content, the grain size of PMT thin film decrease slightly, and the lattice structure of PMT thin film will change from tetragonal to cubic when the Mg content over 8 mole%. The relative dielectric constant of PMT thin film increases from 25 up to 91. The tan

A series of PMMA/silica hybrid composites were prepared by a sol-gel process in different catalytic and drying. Their thermal properties were analysized by DSC and TGA, the micro-structures by SEM, and the chemical reactions by FTIR. The highest decomposed temperature of these hybrid composites were found for samples prepared at low pH due to the hydrogen bonding. DSC data indicated the samples cured at 25 and 140 oC existed a higher Tg due to unhydrolyzed TEOS. The heat-treated hybrid composites exhibited more compact structures. The size of SiO2 particles from SEM increases with increasing drying temperature and pH value. The hybrid composites prepared in acid condition showed more Si-O-Si bonding than Si-O-C bonding in FTIR. In addition, in FTIR spectra the shifts have been observed from a non-hydrogen-bonded C=O at 1733cm-1 to a hydrogen-bonded carbonyl at 1725cm-1.

The lithium tantalite [LiTaO3,abbreviated to LT] thin films were deposited on Pt/SiO2/Si substrates by spin coating with sol-gel processing and rapid thermal processing in this thesis. 1,3 propanediol was used as solvent to minimize the number of cycles of spin coating and drying processes to obtain the desired thickness of thin film. By changing the heating rate (600~3000¢J/min) and the heating temperature (500~800¢J), the effects of various processing parameters on the thin films growth are studied. The effects of various heating rate on the response of pyroelectric IR detector devices are studied also. Experimental results reveal that the heating rate will influence strongly on grain size, dielectricity, ferroelectricity and pyroelectricity of LT thin films. With the increase of heating rate, the grain size of LT thin film decreases slightly, and the C-axis orientation is enhanced. The relative dielectric constant of LT thin film increases from 28 up to 45.6, the tand increases from 0.033 to 0.134, Ec increases from 122 KV/cm to 183 KV/cm, Pr increases from 7.45 mC/cm2 to 12.12 mC/cm2, and g increases from 9.33´10-9 C/cm2K up to 2.66´10-8 C/cm2K, respectively, as the heating rate increases form 600 up to 3000¢J/min. In addition, the results also show that the LT thin film possesses the largest figures of merit Fv (2.19¡Ñ10-10 Ccm/J) and Fm (4.01¡Ñ10-9 Ccm/J) at the heating temperature of 700¢J and heating rate of 1800¢J/min. The voltage responsivities (Rv) measured at 80 Hz increase from 5496 to 8455 V/W and the specific detecivities (D*) measured at 300 Hz increase from 1.94¡Ñ108 to 2.38¡Ñ108 cmHz1/2/W with an increase of heating rate from 600 to 1800¢J/min. However, the voltage responsivity and the specific detecivity decrease with heating rate in excess of 1800¢J/min. The results show that LT1800 pyroelectric thin film detector exists both the maximums of voltage responsivity and specific detecivity. Therefore, LT1800 thin film exhibits the best IR characteristics for detector material.

The prevention and control of salmonellae in commercial swine operations are becoming increasingly important. The current approach focuses on identifying sources and/or origins of salmonellae contamination before swine are processed for human consumption. The objective of the current study was to assess strain variability among salmonellae grouped by serotype and to determine common origins of contamination (farm or slaughter plant). Salmonellae were previously collected from swine at slaughter, serotyped by the National Veterinary Services Laboratory and stored at - 70??C. Pulsed-field gel electrophoresis (PFGE) was performed to genotypically characterize serotypic isolates using restriction endonuclease XbaI. Dendrogram comparisons were also used to assess genotypic similarity when multiple genotypes existed. This study found PFGE to be more discriminatory than serotyping indicating that multiple genotypic strains existed among selected serotypes. On the basis of PFGE results alone, origins of contamination could not be determined in this study. It is suggested by the author, that origins of contamination could be further defined pending future research, in which in-depth longitudinal studies are included. When used as an adjunct to conventional typing methods, PFGE may prove to be a substantial subtyping system in epidemiologic investigations to identify point-of-entry contaminants to the food chain.

Fractured reservoirs have always been considered poor candidates for enhanced oil recovery. This can be attributed to the complexities involved in understanding and predicting performance in these reservoirs. In a fractured system, the high permeability fracture forms the preferred pathway for the injected fluids, and a large amount of oil that is stored in the matrix is bypassed. Hence, a good understanding of multiphase fluid flow in fractures is required to reduce oil bypass and increase recovery from these reservoirs. This research investigates the effect of heterogeneity and injection rates on oil bypass and also the various techniques used for the improvement of sweep efficiency in heterogeneous systems. Several coreflood experiments were performed using homogeneous and heterogeneous cores and a 4th generation X-Ray CT scanner was used to visualize heterogeneity and fluid flow in the core. Porosity and saturation measurements were made during the course of the experiment. The experimental results indicate that injection rates play a very important role in affecting the recovery process, more so in the presence of fractures. At high injection rates, faster breakthrough of CO2 and higher oil bypass were observed than at low injection rates. But very low injection rates are not attractive from an economic point of view. Hence water viscosified with a polymer was injected directly into the fracture to divert CO2 flow into the matrix and delay breakthrough, similar to the WAG process. Although the breakthrough time reduced considerably, water ??leak off?? into the matrix was very high. To counter this problem, a cross-linked gel was used in the fracture for conformance control. The gel was found to overcome ??leak off?? problems and effectively divert CO2 flow into the matrix. This experimental research will serve to increase the understanding of fluid flow and conformance control methods in fractured reservoirs.

The experiments performed for this research were completed to produce solid cerium oxide microspheres by an internal gelation sol-gel process. The motivation for this work was to develop a process that would enable the fabrication of a storage or transmutation form for the plutonium and transuranics (TRU) from the Uranium Extraction Plus (UREX ) used fuel reprocessing process. This process is being investigated by the Department of Energy (DOE) and the Advanced Fuel Cycles Initiative (AFCI) through the Nuclear Energy Research Initiative. The internal gelation production of cerium oxide involves the combination of hexamethylenetetramine (HMTA), urea, and cerium nitrate solutions at ~100oC. Microspheres were produced by injection of a broth solution into a flowing stream of hot silicone oil. The captured microspheres were aged, washed, and then underwent Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and XRay Diffraction (XRD) analysis. The process variables examined in this study include the concentrations of HMTA, urea and cerium nitrate, the process temperature, the postgelation aging time, and the product washing conditions. Over a series of 70 experiments, it was determined that a broth solution containing a mixture of 1.45 M cerium nitrate and 1.65 M HMTA and urea (1:1 ratio) solutions produced the best cerium oxide microspheres. The spheres were aged for 30 to 60 minutes and then washed in hexane to remove the silicone oil and a subsequent series of ammonium hydroxide washes to remove unreacted product and to fully gel the microspheres. Through DSC analysis it was determined that excess wash or unreacted product may be removed by an exothermic reaction at approximately 200oC. The XRD analysis of unheated spheres showed the presence of cerium oxide with additional cerium-bearing organics. Following heating, the microspheres were completely converted to cerium oxide.