Existing tunable diode laser absorption spectroscopy (TDLAS) sensors for potassium (K) and for water vapor (H2O) and temperature were combined to enable simultaneous measurements in combustion and gasification processes. In-situ real-time detection of the above mentioned combustion parameters will improve the understanding of ash-formation during thermochemical conversion of biomass. Simultaneous measurements facilitate the experimental procedure and decrease the methodological uncertainty introduced by the heterogeneous nature of the pellets. The K sensor is based on direct absorption spectroscopy (DAS), whereas the H2O system employs wavelength modulation spectroscopy (WMS) together with two-line thermometry for temperature assessment. Two methods for combining the laser beams were evaluated, the first involving dichroic elements, the second using available fiber optic combiners. The latter method was considered advantageous. An existing LabVIEW program was modified to allow for simultaneous signal generation and data acquisition for both sensors. The sensors were then tested separately in a low pressure K cell and in ambient air. The combined sensor was applied to simultaneous measurements above various pelletized biofuels during combustion in a single pellet reactor (SPR). Significant difference in absolute concentration and time histories were observed between fuels, in particular for K and temperature. Significant K concentrations were only observed during the devolatilization phase. The combined sensor will be useful in fundamental combustion research.

The principal neurons of the medial superior olive (MSO) are considered to be responsible for transforming the temporal information present in the binaural acoustic stimulus into an output encoding sound location along the horizontal axis. Spatial resolution of sound localization depends critically on the time resolution with which MSO neurons can detect microsecond differences in the timing of inputs from the two ears. This fast temporal processing is contingent on voltage gated ion channels. The work presented in this thesis demonstrates that two currents, namely a hyperpolarization activated cationic current and low voltage activated potassium current dynamically interact to regulate the intrinsic time resolution of MSO neurons. We observe that the ability of MSO neurons to perform sub-millisecond temporal processing matures after birth, especially around the time of the clearing of the auditory canal. Hyperpolarization activated cationic current was found to be one of the underlying mechanisms transforming slow immature MSO neurons into temporally precise adult MSO neurons. / text

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Pb-free piezoelectric materials have grown in importance through increased environmental concern related to the presence of Pb and the subsequent legislation that has arisen including directives such as Waste Electrical and Electronic Equipment (WEEE) and the Restriction of Hazardous Substances Directive (RoHS). While much progress has been made on producing Pb-free bulk materials, the need to integrate these next generation Pb-free piezoelectric materials with substrates to form functional micro devices has received less attention and raises a number of challenges. With respect to the high temperature mixed oxide synthesis method, a simple, cost effective and robust low temperature molten hydroxide synthesis (MHS) method derived from the molten salt synthesis (MSS) method, has been developed to produce K0.5Na0.5NbO3 (KNN) small grain powders and is a method that lends itself easily to industrial scale up. A powder/sol gel composite ink film forming technique has been used to produce KNN thick films on silicon substrates. Characterisation of the produced films has shown the films to exhibit piezoelectric coefficients for un-doped material in the region of 30pC/N. The work will report on the Na ion favouring mechanism of the MSS and the related mechanism of the MHS. The work will also report on the dielectric and piezoelectric characteristics of initial KNN thick films produced and an investigation into use of dopants and process modification to improve the KNN thick film’s characteristics.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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Ce travail représente une contribution de l'étude des mécanismes de fixation des gaz par les métaux. Dans une première partie, théorique, nous avons étudié certains aspects de l'adsorption des gaz par les métaux. 1°) Aspect cinétique: Après avoir examiné les différentes théories existantes pour la cinétique d'adsorption, nous avons élaboré une théorie de synthèse. Elle a permis de classer et de compléter les hypothèses qui peuvent être retenues, notamment en ce qui concerne l'ordre des processus de fixation et de désorption par rapport aux sites d'absorption. Nous avons ainsi montré que la loi classique d'Elovich était un cas particulier de la loi générale d'adsorption, lorsque la désorption est négligeable. Il est apparu que les différentes équations obtenues étaient trop proches les unes des autres pour permettre à une étude expérimentale de préciser dans un cas donné les mécanismes mis en jeu. Cette étude a, en outre, permis de montrer que l'isotherme logarithmique de Temkin pouvait traduire une adsorption en plusieurs couches. 2°) Aspect structural: Nous avons établi une formule qui permet de calculer, à priori, à partir d'un modèle donné, le potentiel de double couche créé lors de l'adsorption. Cette formule plus précise que celle d'Helmoltz, a été testée sur plusieurs cas expérimentaux. Elle permet, inversement, à partir d'une valeur expérimentale du potentiel, de préciser la structure de la couche adsorbée. On a pu ainsi montrer que les liaisons adsorbat-adsorbant étaient très voisines des liaisons chimiques classiques, surtout en ce qui concerne les distances interatomiques, et les moments électriques des liaisons. Ces résultats ont conduit à une relation qui permet de calculer, dans certains cas simples, la chaleur initiale d'adsorption. Les valeurs obtenues sont comparées aux résultats expérimentaux. Les écarts enregistrés dans certains cas plus complexes ont pu être interprétés. 3°) Aspect dynamique : Nous avons étudié, à partir de la théorie des vitesses absolues, l'évolution dynamique d'une molécule de gaz diatomique au voisinage d'un métal. La méthode de calcul préconisée, appliquée au système hydrogène-sodium, a précisé le chemin suivi par la molécule d'hydrogène qui vient se fixer à la surface du sodium. Il apparaît nettement que la molécule d'hydrogène se dissocie à l'adsorption. Dans une deuxième partie, expérimentale, nous avons étudié le mécanisme de fixation de l'hydrogène par les métaux alcalins solides. Nous avons montré que les résultats obtenus pour le sodium, le potassium le rubidium et le césium, s'interprètent par l'intervention d'un mécanisme d'adsorption sur l'hydrure. Par contre, l'hydrogénation du lithium apparaît comme une véritable réaction, conduisant à des lois classiques en cinétique des réactions gaz-solide. La partie cubique de la courbe cinétique n'a pu être interprétée de façon rigoureuse, par contre, la partie linéaire qui la précède apparaît comme une cinétique de demi-réaction d'interface externe. La troisième partie a été consacrée, d'une part, à l'étude expérimentale de l'hydrogénation des métaux alcalins liquides à basse température, d'autre part, à l'étude théorique des perturbations apportées par l'état liquide du métal dans les réactions hétérogènes. On a ainsi fait intervenir la dissolution du produit formé qui modifie les régimes cinétiques de diffusion. On a montré que ce cas se produisait lors de la fixation de l'hydrogène par le sodium liquide. En définitive, nous avons mis en évidence l'extrême importance des phénomènes d'adsorption sur la cinétique des réactions hétérogènes gaz-métal. L'adsorption pouvant intervenir soit par sa cinétique (régime pur d'adsorption), soit par l'équilibre qu'elle crée à l'interface gaz-solide (autres régimes).

Breast cancer is the most prevalent cancer type among Canadian women. Breast cancers originate from the malignant transformation of mammary epithelial cells, which causes them to adopt an uncontrolled cell proliferation phenotype. My research suggests that the activity of specific ion channels (KV10.1, KCa3.1 and TRPM8) contribute to the proliferation of MCF-7 cells, a cell line commonly used to study breast cancer in vitro. Pharmacologically inhibiting the activities of KV10.1 or KCa3.1 channels decreased basal, but not estrogen-stimulated [3H]-thymidine incorporation, demonstrating that these channels contribute to MCF-7 cell proliferation. One way K+ channel activity is hypothesized to control cell proliferation is via regulation of membrane potential-dependent Ca2+ influx. Inhibition of KCa3.1 but not KV10.1 channel activity resulted in a membrane potential-dependent decrease in basal Ca2+ influx, suggesting that the way in which KCa3.1 channels contribute to cell proliferation is via regulating Ca2+ influx. In addition, my research also demonstrated that TRAM-34 increased or decreased cell proliferation depending on the concentration used and mitogenesis by TRAM-34 was blocked by estrogen receptor antagonists. TRAM-34 increased progesterone receptor mRNA expression, decreased estrogen receptor-alpha mRNA expression and reduced the binding of radiolabelled estrogen to estrogen receptor protein, in each case mimicking the effects of estrogen. Our finding that TRAM-34 is able to activate the estrogen receptor suggests a novel action of this supposedly specific K+ channel inhibitor and raises concerns of interpretation in its use. TRPM8 channels were also identified in MCF-7 cells, where they appeared to be important Ca2+ entry pathways. Inhibiting the activity of TRPM8 pharmacologically, as well as knocking down TRPM8 mRNA expression decreased cell proliferation, indicating that TRPM8 also contributed to MCF-7 cell proliferation. In conclusion, my research demonstrates that the activities of KV10.1, KCa3.1 and TRPM8 channels contribute to basal breast cancer cell proliferation. These findings suggest that the activity of specific ion channels may be potential targets for future therapeutic agents to treat breast cancer.

Whole farm nutrient budgets (WFNB) enable producers to link dairy herd management with traditional field nutrient management plans. The objective of this study was to calculate WFNBs of nitrogen, phosphorus, and potassium (N, P, and K) at a commercial farm in New Brunswick and in Prince Edward Island. Reliable estimates of N fixation from alfalfa and red clover on the farms were obtained with adjustments to the Høgh-Jensen et al. (2004) dry matter conversion models. The farms had surpluses of N, P, and K. Both farms imported feed as well as nutrient inputs for crop production. Surpluses of all nutrients were typical in comparison to WFNBs of similar dairy farms; however, the nutrient use efficiencies were low. The imported manure and fertilizer used in the crop production components contributed to surpluses of N and P which could likely be reduced to improve overall farm nutrient use efficiency.