Following several reports in the past few years about compositional changes on palladium used as a cathode in heavy water electrolysis, the purpose of this research project was to reproduce this results. Two experiments were performed using two cells connected in series, an experimental cell and a control cell. Both experiments used platinum anodes, the experimental cell had a palladium cathode and the control cell had a platinum cathode. The electrolyte was D20 with H2S04. Radiation was monitored during both experiments. Also temperature and voltage were recorded for both experiments, to allow statements about excess heat of the experimental cell in comparison to the control cell. Both experiments had problems with unequal electrolyte loss, so that no statements about excess heat could be made. No significant radiation was detected in either experiment. Also no compositional changes on the palladium cathodes after electrolysis in both experiments could be detected. Impurities in grain-shaped defects on the palladium cathode before the experiment were found in either experiment. These impurities were Si, Ca, 0, and sometimes also Mg, Na and Fe. Localized findings of Au and Pt, in a distance of 1-2μm to each other, were made on the palladium cathode from the second experiment before electrolysis. Spot, grain-shaped and longitudinal defects were found on the original palladium foil used for the cathodes in either experiment No evidence for fusion, or any other nuclear reaction in the crystal lattice of palladium, used as cathode in heavy water electrolysis, was observed.

Silica is one of the most abundant elements on the planet, has flexible bonding properties and generally excellent stability. Because of these properties, silica has been a vital component in technologies ranging from ancient glassware to modern supercomputers. Silica is able to form a wide range of materials both alone and as a component of larger material frameworks. Porous silica based nanomaterials are rapidly growing in importance because of their many applications in a wide variety of fields. This thesis focuses on the synthesis of silica based porous nanomaterials: nanocrystalline zeolites, mesoporous silica nanoparticles, and iron oxide core/shell nanocomposites. The synthetic conditions of these materials were varied in order to maximize efficiency, minimize environmental impact, and produce high quality material with far reaching potential applications. The materials were characterized by physicochemical techniques including Transmission Electron Microscopy, Dynamic Light Scattering, Powder X-Ray Diffraction, Solid State NMR, and Nitrogen Adsorption Isotherms. The materials were evaluated and conditions were controlled to produce high yields of quality nanomaterials and hypothesize methods for further synthetic control. The products will be used in studies involving nanoparticle toxicity, environmental remediation, and drug delivery.

Many types of chemotherapeutic agents have been developed to target specific mechanisms within the body that control the progression of cancer, though few have been able to circumvent the existing problems associated with the treatments. The current remedies entail grueling drug regimens and toxic side effects that may undermine the effectiveness of the drugs. Cisplatin, a common nitroplatinum(II) drug widely used to treat a variety of cancers, is administered intravenously and circulates systemically, affecting healthy regions of the body as well. Resistance to cisplatin is increasing and the need for new, less toxic medication must be met for future success in cancer therapy. Our lab has synthesized novel nitroplatinum(IV) cisplatin complexes (PH1-14) that may evade these problems. We examined the effects of these compounds on cell viability, as well as effects on cancer-specific mechanisms such as nitric oxide (NO) production, angiogenesis, and the STAT signaling pathways. In vitro studies demonstrated that PH1-11 and PH14 demonstrated greater efficacy at inhibiting cell proliferation with lower IC50 values that ranged from 41-58 uM (as compared with cisplatin IC50 = 66 uM). Data from NO assays were inconclusive, though there was elevated expression of inducible nitric oxide synthase in cells treated with PH3 and PH11. We also found that PH9 was able to inhibit STAT dimerization at concentrations as low as 0.3 uM. PH9 also decreased VEGF and HIF-1α expression, thereby inhibiting angiogenesis. The activity of the PH complexes was also studied in C57BL/6 mice inoculated with murine bladder MB49 tumors. The experimental group showed significantly slower tumorigenesis and smaller tumors as compared with the control group. Toxicological analyses of the blood via metabolic assays showed that no nephrotoxicity was observed in dosages of less than 7 mg drug/kg. We conclude from these results the potential for the use of novel mechanisms in the treatment of cancers. This work will guide future investigations of these drugs in further preclinical trials and also introduce an alternative to the traditional chemotherapeutic agents.

No description available.

Transparent conductive oxides (TCOs) and polycrystalline silicon (poly-Si) thin-films are very promising for application in photovoltaics. It is extremely challenging to develop cheap TCOs and poly-Si films to make photovoltaic devices. The aim of this thesis is to study sputtered aluminum-doped ZnO TCO and poly-Si films by solid-phase crystallization (SPC) for application in low-cost photovoltaics. The investigated aspects have been (i) to develop and characterize sputtered aluminum-doped ZnO (ZnO:Al) films that can be used as a TCO material on crystalline silicon solar cells, (ii) to explore the potential of the developed ZnO:Al films for application in ZnO:Al/c-Si heterojunction solar cells, (iii) to make and characterize poly-Si thin-films on different kinds of glass substrates by SPC using electron-beam evaporated amorphous silicon (a-Si) [referred to as EVA poly-Si material (SPC of evaporated a-Si)], and (iv) to fabricate EVA poly-Si thin-film solar cells on glass and improve the energy conversion efficiency of these cells by post-crystallization treatments. The ZnO:Al work in this thesis is focused on the correlation between film characteristics and deposition parameters, such as rf sputter power (Prf), working gas pressure (Pw), and substrate temperature (Tsub), to get a clear picture of film properties in the optimized conditions for application in photovoltaic devices. Especially the laterally non-uniform film properties resulting from the laterally inhomogeneous erosion of the target material are investigated in detail. The influence of Prf, Pw and Tsub on the structural, electrical, optical and surface morphology properties of ZnO:Al films is discussed. It is found that the lateral variations of the parameters of ZnO:Al films prepared by rf magnetron sputtering can be reduced to acceptable levels by optimising the deposition parameters. ZnO:Al/c-Si heterojunction solar cells are fabricated and characterized to demonstrate the feasibility of the fabricated ZnO:Al films for application in heterojunction solar cells. In this application, expensive indium-tin oxide (ITO) is usually used. Under the standard AM1.5G spectrum (100 mW/cm2, 25 ??C), the best fabricated cell shows an open-circuit voltage of 411 mV, a short-circuit current density of 30.0 mA/cm2, a fill factor of 66.7 %, and a conversion efficiency of 8.2 %. This is believed to be the highest stable efficiency ever reported for this type of cell. By means of dark forward current density-voltage-temperature (J-V-T) measurements, it is shown that the dominant current transport mechanism in the ZnO:Al/c-Si solar cells, in the intermediate forward bias voltage region, is trap-assisted multistep tunneling. EVA poly-Si thin-films are prepared on four types of glass substrates (planar and textured glass, both either bare or SiN-coated) based on evaporated Si, which is a cheaper Si deposition method than the existing technologies. The textured glass is realized by the UNSW-developed AIT process (AIT = aluminium-induced texture). The investigation is concentrated on finding optimized process parameters and evaluating film crystallization quality. It is found that EVA poly-Si films have a grain size in the range 0.8-1.5 ??m, and a preferential (111) orientation. UV reflectance and Raman spectroscopy measurements reveal a high crystalline material quality, both at the air-side surface and in the bulk. EVA cells are fabricated in both substrate and superstrate configuration. Special attention is paid to improving the Voc of the solar cells. For this purpose, after the SPC process, the samples receive the two post-crystallization treatments: (i) a rapid thermal anneal (RTA), and (ii) a plasma hydrogenation. It is found that two post-crystallization treatments more than double the 1-Sun Voc of the substrate-type cells. It is demonstrated that RTA improves the structural material quality of the cells. Furthermore, a hydrogenation step is shown to significantly improve the electronic material quality of the cells. Based on the RTA???d and hydrogenated EVA poly-Si material, the first mesa-type EVA cells are fabricated in substrate configuration, by using sputtered Al-doped ZnO as the transparent front contact. The investigation is focused on addressing the correlation between the type of the substrate and cell performance. Optical, electrical and photovoltaic properties of the devices are characterized. It is found that the performance of EVA cells depends on the glass substrate topography. For cells on textured glass, the AIT texture is shown to have a beneficial effect on the optical absorption of EVA films. It is demonstrated that a SiN barrier layer on the AIT-textured glass improves significantly both the crystalline quality of the poly-Si films and the energy conversion efficiency of the resulting solar cells. For cells on planar glass, a SiN film between the planar glass and the poly-Si film has no obvious effect on the cell properties. The investigations in this thesis clearly show that EVA poly-Si films are very promising for poly-Si thin-film solar cells on glass.

A combination of surface analytical techniques, colloid probe Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS) was used to optimise the grafting density of covalently attached 5, 20 and 40 kDa methoxy-terminated PEO layers (under marginal solvation (cloud point) conditions for the PEO molecules). The combination of these techniques allowed us to relate the PEO layer density and molecular conformations to the range, magnitude and types of forces generated by coatings of various grafting densities. The key optimisation parameter was the grafting time with the concentration of PEO in solution having a weaker effect. Oxidation of the substrate occurred, but did not significantly limit the surface density of the functional groups used to chemically attach the PEO molecules. Interactions between the substrate and silica were electrostatic in origin and did not contribute to the interaction between silica and the PEO surfaces due to salt screening effects Surfaces with dense, highly stretched PEO layers (brushes) generated purely repulsive forces at all separation distances, arising from compression by the silica spherical probe used. The force profiles for lower density surfaces comprised long-ranged attractive and short-ranged repulsive forces. The attractive forces were most likely due to attractive bridging interactions between the PEO chains and the SiO2 surface. For low grafting densities, i.e. inter-chain grafting distances, s &gt ??RF, the PEO layers were not strongly stretched and free to adsorb onto the opposing silica surface. XPS analysis demonstrated that HSA and Fibrinogen adsorbed onto low density 20 kDa PEO coatings (s &gt ??RF), most likely via diffusion through the PEO layer. No protein adsorption was found (detection limit &gt 10 ng/cm2) on high density, ???strongly stretched brush??? coatings (s &lt ?? RF). Analysis of data from the more sensitive Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) techniques indicated that low amounts of adsorbed HSA, lactoferrin, lysozyme, and IgG were present on high density 20 and 40 kDa surfaces; the most likely explanation being attractive interactions between the proteins and the PEO layers during the protein adsorption experiments. ToF-SIMS data obtained for the strongly stretched (s &lt ?? RF) 5 kDa PEO surfaces suggested that no protein was adsorbed, in line with the XPS data for the same surfaces.

Introduction: The enzyme, inducible nitric oxide synthase (iNOS), is upregulated in the airway epithelium in patients with allergic asthma resulting increased nitric oxide production. The concentration of nitric oxide in exhaled air (FENO) correlates with the degree of eosinophilic airway inflammation and has been proposed as a new breath test to assist in the management of asthma. Key Aims: To determine the predictive accuracy of FENO compared with conventional testing in the diagnosis of asthma. To assess the performance characteristics of FENO to predict steroid responsiveness compared with the conventional approach in patients presenting with non-specific respiratory symptoms. To assess the role of FENO compared with conventional guidelines-based approach as a guide to adjusting inhaled corticosteroid therapy in patients with chronic persistent asthma. Methods: Consecutive patients referred with chronic undiagnosed respiratory symptoms were enrolled. Comparisons were made between FENO, induced sputum analysis and other conventional tests (including peak flow variation, spirometry, response to oral steroid challenge) for predicting the presence of asthma in the first study, and for predicting response to four weeks inhaled fluticasone treatment in the second study. In the third study, 110 subjects with chronic persistent asthma were enrolled into a single-blind placebo-controlled study during which subjects were randomly allocated to have their corticosteroid (fluticasone) dose adjusted on the basis of either FENO measurements or an algorithm based on conventional guidelines. The main outcomes were the frequency of asthma exacerbations and the mean daily dose of inhaled corticosteroid. Results: In the first study, 17 of 47 consecutive patients were diagnosed with asthma. Sensitivities for the conventional tests (0-47%) were lower than for FENO (88%) and sputum eosinophils (86%), with overall significantly greater diagnostic accuracy for FENO and sputum eosinophils. Fifty-two consecutive subjects completed the second study. When compared to the conventional tests, the predictive powers for FENO were consistently greater than for almost all other baseline measurements used to predict steroid responsiveness, with an optimum cut point of 47 ppb. In the third study, the exacerbation rates were 0.49 (95% C.I. 0.20, 0.78) per patient per year in the FENO group and 0.90 (95% C.I. 0.31, 1.49) in the control group, representing a nonsignificant reduction of 45.6 percent (95% C.I. -78.5, 54.5%) in the FENO group. The final mean daily doses of fluticasone were significantly lower in for the FENO group compared with the conventional group (370 [mu]g/day (95% C.I. 263, 477) vs 641 [mu]g/day (95% C.I. 526, 756) respectively; p=0.003). There were no significant differences in other markers of asthma control, use of oral prednisone, pulmonary function, or levels of airway inflammation (sputum eosinophils). Conclusions: FENO is comparable to induced sputum analysis and superior to the conventional methods currently used including peak flows and spirometry as a dignositic for asthma and as a predictor of steroid responsiveness in patients with chronic respiratory symptoms. FENO measurements as a guide to adjusting inhaled corticosteroid therapy compared to the conventional guidelines based approach results in significantly lower maintenance doses being achieved without compromising asthma control. The results of this thesis provide evidence to support the use of FENO measurements in routine clinical practice as a tool to improve the overall management and diagnosis of asthma.

Essential hypertension is defined as a chronic elevation of blood pressure of unknown cause. Though a definitive trigger for this change in blood pressure has not been established, there is a strong association with an upregulation of sympathetic output from the central nervous system. There are a number of central autonomic nuclei involved in the maintenance of blood pressure, including the brainstem regions of the nucleus tractus solitarii (NTS), caudal ventrolateral medulla (CVLM), rostral ventrolateral medulla (RVLM), the sympathetic preganglionic neurons (SPNs) within the intermediolateral cell column (IML) of the spinal cord, as well as forebrain regions such as the paraventricular nucleus (PVN) of the hypothalamus. Within these centers, a vast number of neurotransmitters have been identified that contribute to the control of blood pressure, including glutamate, angiotensin II, serotonin, neurotensin, neuropeptide Y, opioids and catecholamines. Recognition of the role of nitric oxide (NO) and its multiple influences over the neural control of blood pressure is gaining increasing significance. Nitric oxide is a unique modulatory molecule that acts as a non-conventional neurotransmitter. As NO is a gas with a short half-life of 4 – 6 seconds, its’ synthesising enzyme, nitric oxide synthase (NOS) is often used as a marker of location of production. Once activated, the best-known “receptor” for NO is soluble guanylate cyclase (sGC), which drives the production of cyclic guanosine monophosphate (cGMP). Identifying the presence of cGMP can therefore be used to determine sites receptive to NO. Previous studies examining the role of NO in the central autonomic control of blood pressure have focused predominantly upon application of either excitatory or inhibitory drugs into the key central autonomic regions and assessing pressor or depressor effects. This thesis aims instead to study the neuroanatomical relationship and functional significance of NO and cGMP expression in the brain and spinal cord of a hypertensive and normotensive rat model. In the first experimental chapter (Chapter 3), a comparative neuroanatomical analysis of neuronal NOS expression and its relationship with cGMP in the SPN of mature Spontaneously Hypertensive Rats (SHR) and their controls, Wistar Kyoto (WKY) was undertaken. Fluorescence immunohistochemistry confirmed the expression of nNOS in the majority of SPN located within the IML region of both strains. However, a strain specific anatomical arrangement of SPN cell clusters was evident and while there was no significant difference between the total number of SPN in each strain, there were significantly fewer nNOS positive SPN in the SHR animals. All nNOS positive SPN were found to express cGMP, and a novel subpopulation of nNOS negative, cGMP-positive SPN was identified. These cells were located in the medial edge of the IML SPN cell group. These results suggest that cGMP is a key signalling molecule in SPN, and that a reduced number of nNOS positive SPN in the SHR may be associated with the increase in sympathetic tone seen in essential hypertension. The second experimental chapter (Chapter 4) aimed to determine if reduced numbers of nNOS containing SPN translated into reduced detectable cGMP. The functional significance of cGMP signalling in the two strains was then examined. Based on previous work by our group, it was predicted that reduced nNOS in the SHR would translate into reduced cGMP and that intrathecal administration of exogenous cGMP in the spinal cord would drive a differential pressor response in the two animal strains. Immunohistochemical techniques confirmed that within each SPN, the relative level of cGMP expression was significantly reduced in the SHR when compared to the WKY. Intrathecal application of 8-bromo-cGMP, a drug analogous to cGMP, increased blood pressure in both strains and had a differential and dose dependent effect, causing only a small increase in blood pressure in anaesthetised WKY animals, while driving a significant pressor response in the SHR. This finding raised the novel hypothesis that in the SHR, reduced nNOS expression is not a driver of hypertension, but is instead a protective mechanism limiting the potent pressor effects of cGMP within SPN. The third experimental chapter (Chapter 5) examines the expression of neuronal and inducible isoforms of NOS (nNOS, iNOS) within the RVLM of SHR and WKY rats. Reverse transcription-polymerase chain reaction (RT-PCR) was used to analyse the level of mRNA expression and immunohistochemistry was then used to further analyse protein levels of nNOS. Total RNA was extracted and reverse transcribed from the RVLM of mature male WKY and SHR. Quantitative real-time PCR indicated that relative to WKY, mRNA levels for nNOS was significantly higher in RVLM of the SHR. This was confirmed immunohistochemically. When compared to iNOS, nNOS was expressed at significantly higher levels overall, however there was no difference in iNOS mRNA expression between the two strains. This demonstration of differential expression levels of nNOS and iNOS in the RVLM raises the possibilities that (i) NO production is up-regulated in the RVLM in SHR in response to increased sympathetic activity in order to re-establish homeostatic balance or alternatively that (ii) an alteration in the balance between nNOS and iNOS activity may underlie the genesis of augmented sympathetic vasomotor tone during hypertension. The fourth experimental chapter (Chapter 6) extends the observations in Chapter 5 through examination of the expression of cGMP and sGC within the RVLM. There is strong functional evidence to suggest that NO signalling in the RVLM relies on cGMP as an intracellular signalling molecule and that this pathway is impaired in hypertension. Immunohistochemistry was used to assess cGMP expression as a marker of active NO signalling in the C1 region of the RVLM, again comparing SHR and WKY animals. Fluorescence immunohistochemistry on sections of the RVLM, double labelled for cGMP and either nNOS or phenylethylamine methyl-transferase (PNMT) failed to reveal cGMP positive neurons in the RVLM from aged animals of either strain, despite consistent detection of cGMP immunoreactivity neurons in the nucleus ambiguus from the same or adjacent sections. This was demonstrated both in the presence and absence of the phosphodiesterase inhibitor isobutylmethylxanthine (IBMX) and in young vs. aged animals. In-vitro incubation of RVLM slices in the NO donor DETA-NO or NMDA did not reveal any additional cGMP neuronal staining within the RVLM. In all studies, cGMP was prominent within the vasculature. Soluble guanylate cyclase immunoreactivity was found throughout the RVLM, although it did not co-localise with the PNMT or nNOS neuronal populations. Overall, results suggest that within the RVLM, cGMP is not detectable in the resting state and cannot be elicited by phosphodiesterase inhibition, NMDA receptor stimulation or NO donor application. A short time course of cGMP signalling or degradation not inhibited by the phosphodiesterase inhibitor utilised (IBMX) in the RVLM cannot be excluded. The final experimental chapter (Chapter 7) examines cGMP expression in magnocellular and preautonomic parvocellular neurons of the PVN. Retrograde tracing techniques and immunohistochemistry were used to visualise cGMP immunoreactivity within functionally, neurochemically and topographically defined PVN neuronal populations in Wistar rats. Basal cGMP immunoreactivity was readily observed in the PVN, both in neuronal and vascular profiles. Cyclic GMP immunoreactivity was significantly higher in magnocellular compared to preautonomic neuronal populations. In preautonomic neurons, the level of cGMP expression was independent on their subnuclei location, innervated target or neurochemical phenotype. The data presented in this chapter indicates a highly heterogeneous distribution of basal cGMP levels within the PVN, and supports work by others indicating that constitutive NO inhibitory actions on preautonomic PVN neurons are likely mediated indirectly through activation of interneurons. Summary Together, these studies comprise a detailed analysis of the neuroanatomical expression of NO and its signalling molecule cGMP in key central autonomic regions involved in the regulation of blood pressure. Under resting or basal conditions, the studies demonstrate notable differences in the expression of NO synthesising enzymes between normotensive and hypertensive animals, and correlating changes in the downstream signalling molecule cGMP. In the spinal cord, novel functional differences in cGMP activity were also demonstrated. In the RVLM, although differences in nNOS were demonstrated, cGMP expression could not be readily detected in either the WKY or SHR, while in contrast within the PVN, cGMP was detected in both magnocellular and parvocellular neuronal populations. Conclusion This thesis gives insight into the physiological role of NO and cGMP as mediators of central blood pressure control. The results presented indicate that the NO-cGMP dependent signalling pathway may not be the dominant driver responsible for maintaining high blood pressure in the SHR model of essential hypertension, and that there is no globally consistent pattern of expression, and indeed the role of NO as a mediator of pressor and depressor function may vary between the autonomic regions examined. Further, it is possible that this pathway is only recruited during activation of reflex homeostatic pathways or during times of marked physiological stress, and that the differences we see in basal expression between the normotensive and SHR animals are instead a result of compensatory mechanisms.

In this thesis, we study the effects of doping in two-dimensional quantum antiferromagnets. We consider cases where the undoped parent compound is a Mott insulator with long-range antiferromagnetic order and focus on the low-doping situations. The limit of localized impurities is studied in a system consisting of a host magnet and two additional weakly coupled spins. We derive the effective Hamiltonian describing the interaction between these impurities as a function of their distance and show that it exhibits xyz anisotropy, leading to NMR and EPR line broadening. We calculate the magnetization disturbance in the host magnet induced by a single impurity and find that it always enhances Neel order. Relaxing the localization constraint, we investigate the single-hole dynamics of the t-J model on the honeycomb lattice. Using exact diagonalizations, series expansion and the self-consistent Born approximation, we calculate the quasi-particle dispersion, bandwidth and residues and compare our findings with the well-established results for the square lattice. Similar to the latter case, we find an almost flat band along the edges of the magnetic Brillouin zone and well-defined hole pockets around the corners. The most important part of this thesis is devoted to the magnetic properties of lightly doped La2-xSrxCuO4, the simplest and by far most studied cuprate superconductor. Starting from the undoped parent compound, we calculate the spin-wave spectrum and the spin-flop transitions in a uniform magnetic field at zero temperature. We then consider the low-doping regime and derive the effective field theory describing the spin dynamics in insulating La2-xSrxCuO4, x ≤ 0.055, at low temperature. The spin structure resulting from the spiral solution of the extended t-J model, obtained by taking into account the Coulomb trapping of holes by Sr ions, is confined in the copper-oxide planes. Our solution explains why the incommensurate structure is directed along the orthorhombic b axis and allows us to calculate the positions and shapes of the neutron scattering peaks numerically. These results are in perfect agreement with experimental data. We also show that topological defects (spin vortex-antivortex pairs) are an intrinsic property of the spin-glass ground state.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2007. / Title from title screen (site viewed Dec. 5, 2007). PDF text: xi, 166 p. : ill. ; 9 Mb. UMI publication number: AAT 3273922. Includes bibliographical references. Also available in microfilm and microfiche formats.