In this thesis, the resistance switching characteristic of Zn:SiO2 -based memory was studied. The resistive memory was fabricated by sputtering to deposit the Metal/Insulator/Metal (MIM) structure. The top and bottom layers were made by Pt and TiN respectively, and the insulator was Zn:SiO2 grown by co-sputtering with SiO2 and Zinc. We found that doping Zinc into SiO2 insulator induced the resistive switching characteristic. By the treatment of supercritical carbon dioxide (SCCO2) in Zn:SiO2 -based device,the operation current would decrease. In the result of x-ray electron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) , it showed that the defects in Zn:SiO2 thin-film were reduced. And the electric conduction mechanism of low resistance state made a change from ohmic conduction to hopping conduction. To emerge spontaneous phenomenon of hopping conduction, the memory devices were fabricated with a multi-layer structure. In Auger electron spectroscopy (AES), we found the signal of zinc, split into three different kinds of peaks, which met the multi-layer structure. From I-V sweep measurement, the multi-layer structure device could be appeared the spontaneous hopping conduction mechanism. In order to find out the initial state of electric conduction mechanism .We measured the device of Pt/Zn:SiO2/TiN with constant current forming. We found the initial state of electric conduction path out successfully, and it¡¦s operation current below 10 uA.

Semiconductor nanocrystals are expected to play an important role in the development of new generation of microelectronic and photonic devices such as light emitting diodes and memory elements. Optimization of these devices requires detailed investigations. Various spectroscopic techniques have been developed for material and devices characterization. This study covers the applications of the following techniques for the analysis of nanocrystalline materials: Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, X-Ray Diffraction (XRD) and X-Ray Photoelectron (XPS). Transmission Electron Microscopy (TEM) and Secondary Ion Mass Spectrometry (SIMS) are also used as complementary methods. Crystallinity ratio, size, physical and chemical environment of the nanostructures were probed with these methods. Si and Ge nanocrystals were formed into the oxides Al2O3 and SiO2 by ion implantation, magnetron sputtering and laser ablation methods. FTIR and XPS are two methods used to extract information on the surface of the nanocrystals. Raman and XRD are non destructive and easy-to-operate methods used widely to estimate the crystallinity to amorphous ratio and the sizes of the nanocrystals. In this study, the structural variations of SiO2 matrix during the formation of Si nanocrystals were characterized by FTIR. The shift in position and changes in intensity of the Si-O-Si asymmetric stretching band of SiOx was monitored. An indirect metrology method based on FTIR was developed to show the nanocrystal formation. Ge nanocrystals formed in SiO2 matrix were investigated using FTIR, Raman and XRD methods. FTIR spectroscopy showed that Ge atoms segregate completely from the matrix at relatively low temperatures 900 oC. The stress between the Ge nanocrystals and the matrix can vary in samples produced by magnetron sputtering if the production conditions are slightly different. Si and Ge nanocrystals were formed into Al2O3 matrix by ion implantation of Si and Ge ions into sapphire matrix. Raman, XRD, XPS and TEM methods were employed to characterize the formed nanocrystals. XRD is used to estimate the nanocrystal sizes which are in agreement with TEM observations. The stress on nanocrystals was observed by Raman and XRD methods, and a quantitative calculation was employed to the Si nanocrystals using the Raman results. XPS and SIMS depth profiles of the sample implanted with Si, and annealed at 1000 oC were measured. Precipitation of Si atoms with the heat treatment to form the nanocrystals was observed using XPS. The volume fraction of the SiOx shell to the Si core in Si nanocrystals was found to be 7.9 % at projection range of implantation.

The interactions of the non steroidal anti-inflammatory drug celecoxib with pure and cholesterol containing distearoyl phosphatidylcholine multilamellar vesicles were studied using Fourier transform infrared spectroscopy, differential scanning calorimetry and turbidity technique at 440 nm. The results reveal that celecoxib exerts opposing effects on membrane order in a concentration dependent manner while cholesterol disorders and orders the membrane in the gel and liquid crystalline phase, respectively. Ternary mixtures of DSPC/Cholesterol/celecoxib behave similar to cholesterol with a small effect of celecoxib. While celecoxib decreases fluidity of the DSPC membranes, cholesterol shows an opposite effect, and in ternary mixtures, a dominant effect of cholesterol is observed. Celecoxib induces opposite effects on the hydration status of the carbonyl groups in the binary system whereas / cholesterol induces hydrogen bonding around this group. An evidence of phase separation has also been observed for all three systems (DSPC/celecoxib, DSPC/Chol, and DSPC/Chol/celecoxib). In addition, a possible location of celecoxib in the interfacial region of the membrane has been proposed. Finally, penetration of celecoxib into the hydrophobic core of the ternary system at high cholesterol concentrations and formation of a new phase has also been suggested. Thus, depending on the concentration used, celecoxib induces significant changes in the biophysical properties of membranes that may aid in understanding its mechanism of action. Furthermore, highly complex interactions take place in ternary membrane systems and further investigations are needed to explore them in detail.

Synthetic diamond thin films have potential for fabricating high-temperature semiconducting and optical devices because of its extraordinary properties. In this work, a microwave plasma chemical vapor deposition system has been setup. A two-steps deposition process will be applied for the growth of boron-doped diamond on silicon and on porous silicon. The effects of temperature, microwave power and of doping concentration of B2O3 have been studied by varying the growth parameters. The doping source of B2O3 solved in C2H5OH is applied with carrying gas of Ar. To vary the concentration of boron with the flow of Ar is controlled mixing into a reaction gas of CH4 and H2 mixture. Polycrystalline diamond thin films are examined by Raman, XRD and FTIR. In the SEM photograph a nano-wires structure has been found for higher doping of B2O3. A higher temperature the growth rate of the boron-doped diamond films will increase and the shape of crystallites will tend to polycrystalline. The diamond growth is in multi steps and the mechanism of deposition will change when the boron-doped diamond film grows up to a critical thickness. In this work a smooth diamond film was successfully grown on porous silicon without the step of nucleation.

This dissertation describes the work done on two distinct projects. In the first part I sought to unravel the mechanisms that underlie the activity-dependent modulation of response in the excitation-secretion coupling of the neurohypophysis. In the second part, I optically monitored and analyzed the secondary structure changes accompanying amyloid fibril formation along multiple pathways, under both denaturing and near-physiological conditions. Neuronal plasticity plays an important role in regulating various biological systems by modulating release of hormones or neurotransmitters. The changing response to the same stimulus, depending on the context and previous stimulation events, is also the basis of learning and all higher order brain functions. The mechanisms behind this modulation are widely varied, and are often poorly understood in specific tissues. In this work, we examined excitation-secretion coupling in the neurohypophysis, a tissue composed of densely packed axons that secretes the hormones arginine vasopressin and oxytocin. The release of hormones depends not only on the overall level of activity in the gland, but also upon the specifics of the temporal pattern of stimulation. By optically monitoring the electrical activity using voltage sensitive dyes, we were able to investigate this plasticity in the intact gland. Varying extracellular potassium concentration in the bath, increasing interstitial space via hypertonic saline, and retarding potassium reuptake with ouabain all showed that extracellular potassium accumulation drives the depression of excitability. This effect is hidden from glass micro-electrode recordings because of the inevitable damage sustained by the surrounding tissue. Furthermore, no calcium mediated release mechanism played any significant role in the depression. Numerical simulations confirmed the findings and give more insight to the details of the mechanism. Deposits of amyloid fibrils, long, unbranched polymeric protein aggregates, are the molecular hallmark for a variety of human diseases, including Alzheimer's disease, Parkinson's disease, and type II diabetes. While the amyloid fibrils all share a characteristic cross-beta sheet structure, the proteins that make up the aggregates have no unifying theme in either native structure or function. In this research, I characterized the structural reordering that accompanies this aggregation using Fourier transform infrared spectroscopy (FTIR). Hen egg white lysozyme forms fibrillar aggregates with two distinct morphologies, depending on the growth conditions. At acidic pH with low ionic concentrations, lysozyme forms the fibrils with standard amyloid morphology. These aggregates are long and stiff but with the cross sectional area of a single monomer. At higher salt concentrations, the aggregation follows another pathway, under which oligomers initially form and later assemble into protofibrils. The oligomeric protofibrils are thicker than the monomeric filaments, but are much more curvilinear. These fibrils are not universally recognized as amyloidogenic aggregates. Using FTIR, I showed that both this aggregates are indeed amyloid structures, but that they are structurally distinct. While it is generally accepted that partial unfolding of the protein is a prerequisite for amyloid fibril formation, we found that native protein can be the substrate for amyloid growth when seeded with preformed oligomeric or protofibrillar aggregates. These seeded fibrils grown under near-physiological conditions are structurally indistinguishable from those grown from partially unfolded protein under denaturing conditions. This incorporation and restructuring of native monomers is characteristic of prion-like assembly.

BCxNy films were characterized as a potential pore sealing layer for low κ dielectrics. The changes in chemical bonding were studied as a function of growth temperature to aid in understanding the variation in electrical performance of these films. Thermal chemical vapor deposition of BCxNy using dimethylamine borane and ethylene were deposited on porous methylsilsesquioxane substrates at 335 °C and 1 Torr. BCxNy was able to seal the porous interface with a thickness of 3.9 nm for both blanket and patterned substrates. BCxNy films deposited over a temperature range of 300-400 °C with dimethylamine borane and either ethylene or ammonia coreactant gas were characterized. Films deposited with ethylene became more concentrated in B at the expense of C with increasing temperature. These films favored C-B intermixing over C-C and B-B bonding at higher temperature. H was detected in the form of B-H and C-H bonds. Films deposited with ammonia became concentrated in N at the expense of B, and favored B-N viii bonding at higher temperatures. H was found in the films as B-H, C-H, and N-H bonds. The amount of H in the films decreased with increasing growth temperature for both ethylene and ammonia coreacted films. The valence band offset of C-rich films increased from 0.17 ± 0.22 eV to 0.32 ± 0.22 eV when deposited at 300°C and 400 °C. For the Nrich films, the valence band offset shifted from 0.26 ± 0.28 at 300 °C to -0.15 ± 0.24 eV at the same deposition conditions. High temperature annealing from 400-800 °C in forming gas caused all BCxNy films to decrease in thickness up to 30%. At the same time, the index of refraction increased, and likely, the dielectric constant. X-ray photoelectron spectroscopy revealed little change in the constituent bonding, suggesting that volatile –H containing species were removed during the annealing process. / text

Microbiological monitoring of water is of primary importance for preservation of human health, particularly in an arid zone like the U.S. southwest. In this work, infrared spectroscopic methods were developed to identify and quantify microorganisms present in water and water-related environmental samples. Focus of the work was primarily on evaluating the impact of various sterilization methods on microorganism physiology as gauged by the non-invasive approach of infrared spectroscopy. This work demonstrates that FTIR techniques can be used to identify changes in the physiology of microorganisms and that for heat treatment, a correlation between spectral changes and the viability of microorganisms can be made.

The byssal adhesion mechanism of the biofouling species Dreissena polymorpha was investigated using a combination of studies on synthetic peptide mimics of tandem repeat sequences from byssal component Dreissena polymorpha foot protein 1 (Dpfp-1) and characterization of the regions of the byssus. A 20-residue fusion peptide incorporating two Dpfp-1 repeat sequences adopts a random coil and β-turn conformation in solution, and spontaneously forms a film at the solid-liquid interface in the presence of iron (III) cations. Infrared characterization of the byssus Amide I region showed that β-sheets dominate its secondary structure, although the proportion of different secondary structures varies between regions. Matrix-assisted laser desorption ionization (MALDI) mass spectrometry of intact byssal regions identified previously unknown differences in the composition of byssal threads, plaques, and the adhesive interface, which are believed to correlate to the different roles of these components in the overall structure.

The byssal adhesion mechanism of the biofouling species Dreissena polymorpha was investigated using a combination of studies on synthetic peptide mimics of tandem repeat sequences from byssal component Dreissena polymorpha foot protein 1 (Dpfp-1) and characterization of the regions of the byssus. A 20-residue fusion peptide incorporating two Dpfp-1 repeat sequences adopts a random coil and β-turn conformation in solution, and spontaneously forms a film at the solid-liquid interface in the presence of iron (III) cations. Infrared characterization of the byssus Amide I region showed that β-sheets dominate its secondary structure, although the proportion of different secondary structures varies between regions. Matrix-assisted laser desorption ionization (MALDI) mass spectrometry of intact byssal regions identified previously unknown differences in the composition of byssal threads, plaques, and the adhesive interface, which are believed to correlate to the different roles of these components in the overall structure.

In this research, physicochemical changes that took place during roast processing of coffee beans using fluidized air roaster were studied. The results showed that high-temperature-short-time resulted in higher moisture content, higher pH value, higher titratable acidity, higher porous structure in the bean cell tissues, and also produced more aldehydes, ketones, aliphatic acids, aromatic acids, and caffeine than those processed at low-temperature-long-time process. Fourier transform infrared (FTIR) spectroscopy and chemometric analysis showed that clusters for principal components score plots of ground coffee, extracted by a mixture of equal volume of ethyl acetate and water, were well separated. The research indicated that variations in IR-active components in the coffee extracts due to different stages of roast, roasting profiles, and geographical origins can be evaluated by the FTIR technique. / Natural Sciences and Engineering Research Council of Canada (NESRC) and Mother Parkers Tea & Coffee Inc.