Made available in DSpace on 2014-08-20T13:32:57Z (GMT). No. of bitstreams: 1 tese_augusto_schneider.pdf: 1335904 bytes, checksum: 383222cf3cae0eb874a534a96d7cb6a1 (MD5) Previous issue date: 2011-03-29 / Fertility in cattle is highly influenced by metabolic hormones. Of special interest for the reproductive axis are growth hormone (GH) and insulin-like growth factor (IGF-I). The aim of this thesis were 1) to characterize liver GHR and IGF-I expression in postpartum lactating beef cows and its relation to first ovulation; 2) to characterize GHR and IGF-I expression in granulosa and luteal cells; 3) to determine the effect of prepartum somatotropin on the postpartum resumption of ovarian activity; and 4) to determine the effect of the GHR AluI polymorphism on the fertility of Holstein cows. The expression of GHR and IGF-I mRNA in the liver of postpartum lactating beef cows was not different between ovulatory and non-ovulatory cows, as well as it not change from 0 to 40 days postpartum. These data indicated that beef cows did not go through the same pattern of dissociation of the GH/IGF-I as observed for dairy cattle. Regarding the characterization of GHR and IGF-I expression in luteal and granulosa cells, it was possible to observe that GHR, IGF-I and SOCS expression were clearly higher in luteal than granulosa cells, but not different between atretic and estrogen active follicles. Moreover, GHR and IGF-I expression were not correlated in granulosa and luteal cells. With these results, we choose to focus on strategies in dairy cattle and not based on local regulation of GHR/IGF-I. In this sense, the use of prepartum somatotropin was benefitial in antecipate the resumption of postpartum ovarian activity. Further, treated cows had increased milk production and decreased concentrations of NEFA in the early postpartum. Also, the strategy based on the genotyping of Holstein cows for the GHR AluI polymorphism indicated that cows carrying the AluI(-/-) genotype had lower milk production and shorter calving conception interval. Cows carrying at least one AluI(-) allele also had a shorter calving conception interval and less number of AI per conception. This way, it is clear the importance of the GH/IGF-I system to the reproductive and productive performance of postpartum dairy cows. More studies, with new strategies or combining different strategies can bring even more benefits to the production systems. / A fertilidade em bovinos é muito influenciada por hormônios ligados ao metabolismo. Neste sentido, de especial interesse ao eixo reprodutivo são o hormônio do crescimento (GH) e o fator de crescimento semelhante a insulina I (IGF-I). Assim o objetivos desta tese foram 1) caracterizar a expressão de GHR e IGF-I no tecido hepático de vacas de corte lactantes e sua relação com a primeira ovulação; 2) caracterizar a expressão de GHR e IGF-I em células luteais e da granulosa; 3) avaliar o efeito da somatotropina exógena pré-parto sobre o retorno a atividade ovariana pós-parto; e 4) avaliar o efeito o polimorfismo AluI no gene GHR sobre a fertilidade de vacas da raça Holandês. A expressão de GHR e IGF-I no tecido hepático de vacas de corte lactantes não foi diferente entre vacas que ovularam e não ovularam, bem como não variou sua expressão entre 0 e 40 dias pós-parto. Estes dados indicam que vacas de corte não sofrem a dissociação do eixo GH/IGF-I observada em gado leiteiro. Com relação a caracterização da expressão de GHR e IGF-I em células luteais e da granulosa, foi possível observar que a expressão de GHR, IGF-I e SOCS é claramente maior em células luteais, porém não difere entre folículos atrésicos ou estrogênio ativos. Além disso, o nível de GHR e IGF-I não foi correlacionado em células da granulosa ou luteais. Assim, partiu-se para o teste de estratégias em gado leiteiro e que não focassem na regulação da produção local de IGF-I. Neste sentido, o uso de somatotropina exógena no período pré-parto mostrou um benefício ao antecipar o momento da primeira ovulação pós-parto. Além do mais, as vacas tratadas aumentaram a produção de leite e reduziram o nível circulante de ácidos graxos não esterificados no período pós-parto recente. Por fim, a estratégia de genotipagem de vacas da raça Holandês para o polimorfismo GHR AluI indicou que vacas portadoras do genótipo AluI (-/-) tem menor produção leiteira e menor intervalo parto-concepção. Em geral, vacas que possuem ao menos um alelo AluI(-) apresentaram menor intervalo parto-concepção e menor número de IA por concepção. Portanto, fica clara a importância do sistema GH/IGF-I para o desempenho tanto produtivo como reprodutivo de vacas de leite pós-parto, sendo que mais estudos com novas estratégias, assim como combinando diferente estratégias, podem trazer ainda mais benefícios aos sistemas de produção.

Résumé / Abstract

La croissance rapide du marché des télécommunications a conduit à une augmentation significative du nombre de bandes de fréquences allouées et à un besoin toujours plus grand en terminaux offrant un accès à un maximum de standards tout en proposant un maximum de services. La miniaturisation de ces appareils, combinée à la mise en place de fonctions supplémentaires, devient un vrai challenge pour les industriels. Une solution consiste à utiliser des fonctions hyperfréquences accordables (filtres, commutateurs, amplificateurs,…). A ce jour, trois technologies d'accord sont principalement utilisées : capacités variables, matériaux agiles ou encore MEMS RF. Dans le cadre de cette thèse, nous avons travaillé sur l’optimisation de dispositifs hyperfréquences reconfigurables en utilisant des couches minces ferroélectriques KTN et des diodes varactor. Nos premiers travaux étaient relatifs à l’optimisation des dispositifs hyperfréquences accordables à base de couche minces KTN. Dans ce sens, nous avons tout d’abord caractérisé le matériau KTN en basse et haute fréquence afin de déterminer ses caractéristiques diélectriques et ses caractéristiques en température. Nous avons ensuite réalisé des dispositifs hyperfréquence élémentaires tels des capacités interdigitées et des déphaseurs à base de KTN. Leurs performances ont alors été comparées aux mêmes dispositifs réalisés cette fois à base de la solution la plus utilisée BST. Bien qu’un léger avantage soit acquis à la solution BST, il n’en reste pas moins vrai que les résultats avec le matériau KTN sont très proches indiquant que cette voie peut également, après optimisation, apporter une alternative au BST. La seconde partie de nos travaux concerne la réalisation de filtres planaires accordables en fréquence à base de matériaux KTN et de diodes varactor. Nous avons ainsi réalisé deux filtres passe-bande accordables. Un premier filtre passe-bande de type « open loop » possédant deux pôles agiles en fréquence centrale et un second filtre passe-bande de type SIR rendant possible l’accord de sa fréquence centrale ainsi que de sa bande passante à partir de diodes varactor. Lors de la conclusion sur nos travaux, nous évoquons les suites à donner à ce travail et les perspectives. / The rapid growth of the telecommunications industry has led to a significant increase in the number of allocated frequency bands and a growing need for terminals providing access to an increasing number of standards while offering maximum services. The miniaturization of these devices combined with the implementation of additional functions has become a real challenge for the industry. The use of tunable microwave functions (filters, switches, amplifiers ...) appears as a solution to this issue. In this way, three main technologies are mainly used: variable capacitors, tunable materials and RF MEMS. Within the scope of this thesis work, our investigations focused on tunable microwave devices optimization through the use of KTN ferroelectric thin films and varactor diodes. The first part of our study deals with the optimization of tunable microwave devices based on KTN ferroelectric thin films. In this way, we initially characterized KTN material in low and high frequency to determine its dielectric properties and characteristics according to the temperature. Then, we designed basic microwave devices such as interdigitated capacitors and phase shifters based on KTN thin films. Their performances were then compared with BST solution. Despite results highlighting a slight advantage to BST solution, KTN material, after optimization process, could be a BST alternative solution. In a second part, our work focused on the realization of tunable planar filters based on KTN materials and varactor diodes. We made two tunable bandpass filters. The first one is a center frequency tunable bandpass two pole open loop filter and the second one is a center frequency and bandwidth tunable SIR bandpass filter using varactor diodes. Finally, we discussed follow-up to give to this work and outlooks.

Ce travail de thèse s’inscrit dans le cadre de l’intégration des films minces ferroélectriques de BaxSr(1-x)TiO3 au sein de dispositifs microondes. Dans un premier temps, les caractéristiques diélectriques des films de B0.3S0.7TiO3 déposés par pulvérisation cathodique ont été déterminées. Il a été mis en évidence l’intérêt d’une couche tampon dans le contrôle de l’orientation des films ainsi que son impact dans l’évolution des propriétés diélectriques. L’utilisation d’une structure coplanaire optimisée a été utilisée dans le but de déterminer les évolutions fréquentielles de la permittivité, des pertes ainsi que de l’accordabilité jusqu’à 67 GHz. La caractérisation du matériau a permis la réalisation et la qualification de l’élément de base dans la conception de dispositifs microondes accordables : la capacité ferroélectrique. Le phénomène d’agilité a été mis en exergue au sein de cette structure.Par la suite, une analyse complète a été menée sur un dispositif de type résonateur. Une étude analytique couplée à la réalisation de démonstrateur a permis de mettre en évidence la configuration nous permettant d’exploiter au mieux les propriétés des films de BST. / This work is dedicated to the integration of ferroelectric BaxSr(1-x)TiO3 thin films in microwave devices. Initially, the dielectric properties of B0.3S0.7TiO3 films deposited by radiofrequency magnetron sputtering were determined. It has been demonstrated the influence of a buffer layer in the control of orientation films and the impact in the evolution of dielectric properties. The realization of optimized coplanar waveguide has permit to determine the frequency evolution of permittivity, loss factor and tunability up to 67 GHz. The characterization of the dielectric properties has enabled the realization and qualification of the basic element in the design of tunable microwave devices: the ferroelectric capacitance. The agility property has been highlighted within this structure. Subsequently, a complete analysis was conducted on a resonator. An analytical study coupled with the demonstrator realization highlighted the configuration allowing us to exploit the properties of BST films.

The aim of the work was a processing of ceramic material based on BST for ferroelectric application. Wet chemical techniques based on precipitations and sol-gel methods with ultrasound, hydrothermal or mechanochemical treatment supporting deaglomeration and reducing particle growth were used for BST ceramic powder synthesis. Suitable powders were selected by the evaluation of particle morphology, size and agglomeration, from these powders BST bulk ceramic with defined phase composition and morphology applicable for ferroelectric applications was prepared. It was found, that the most suitable method for preparation of phase pure and nanosized BST powder was sol-gel synthesis with solvothermal treatment (200 °C/48 h). Ceramic with relative density of 85 % TD and with the average grain size of about 1, 22 µm was prepared by pressing and sintering of the powder synthesized by the sol-gel method.

Ferroelectric materials have been extensively studied theoretically and experimentally for many decades. Their ferroelectric, piezoelectric, pyroelectric, dielectric and electro-optical properties offer great promise in various applications such as non-volatile random access memory devices, non linear optics, motion and thermal sensors, and tunable microwave devices. Advanced applications for high dielectric constant insulators and nonvolatile memories in semiconductor industry have led to a meteoric rise of interest in the ferroelectrics recently. As most studied and technically important ferroelectric materials, lead zirconate titanate (PZT) and barium strontium titanate (BST) are widely investigated to understand their properties for potential device applications. Using radio frequency magnetron sputtering, single crystalline PZT and BST thin films have been achieved on SrTiO3 substrates, and been characterized for their structural and electrical properties. Eyeing their different potential applications, ferroelectric, pyroelectric and dielectric properties of PZT and BST thin films were studied. In addition, the introduction of bridge layers (nucleation or buffer layers) grown by molecular beam epitaxy (MBE) has been employed to facilitate the heterostructure growth of PZT thin films on GaN and BST thin films on sapphire substrates. Highly (111)-oriented perovskite PZT thin films were achieved on silicon-doped GaN (0001)/c-sapphire with a PbTiO3/PbO oxide bridge layer. And (001)-oriented BST thin films were grown on a-plane sapphire with an MgO/ZnO bridge layer. This dissertation also discusses the realization of PZT ferroelectric field effect transistors (FeFET). Two different 1T FeFET structures were successfully fabricated and their electrical properties were examined. Ferroelectric behavior was observed in the plot of source-drain current versus gate voltage where it exhibited a large counterclockwise hysteresis with 50% current modulation.

Owing to the large electric-field-dependent permittivity, ferroelectric thin films have attracted a great deal of attention on applications in miniature tunable microwave components with high performance and cost reduction, such as phase shifters, tunable oscillators, delay lines, and antennas. These tunable devices require large change in the dielectric constant with applied field and a low loss at microwave frequencies. As one of the promising ferroelectric materials, barium strontium titanate thin film, especially Ba0.5Sr0.5TiO3 (BST) films, have raises great research interests due to its high dielectric constant, which is tunable in an external electric field, combined with relative low loss at microwave frequencies. Tunable microwave components, such as phase shifter, based on the BST films have been widely investigated. Since the polarization, the significant characterization of ferroelectrics, is very sensitive to distortion in crystal structure of ferroelectrics, strain can be effectively utilized to tailor the dielectric properties of BST films. Due to the lattice-mismatch from the substrate and various deposition conditions, epitaxial BST thin film usually contains residual strain generated during film growth. Strain control by improved deposition technique and implementing thermal treatment as well as choosing suitable substrate has attracted intensive attentions in ferroelectric film fabrication. Theory predicts that high dielectric properties can be achieved when free strain or slightly tensile strain left in the BST thin film at room temperature. Microwave application, such as phase shifter, also expects the enhanced tunability by an applied electric field. In this dissertation, single crystalline BST thin films deposited by radio frequency magnetron sputtering on SrTiO3 and DyScO3 substrates were studied. The crystal structure characteristics, including lattice parameters and film strain, were determined using X-ray diffraction. A new growth technique, three-step technique, was introduced and implemented into BST thin film deposition. The application of this new technique in deposition dramatically reduced the compressive strain in the films. We use microwave measurements on coplanar waveguides to evidence the improvement on dielectric properties achieved by tailoring the film strain. Additionally, we studied the BST film deposited by pulsed laser deposition (PLD) with introducing a sputtered seed layer of BST thin film. Compared with the BST film directly deposited on the substrate by PLD deposition, the films with a seed layer showed a large enhancement on the dielectric constant and tunability. The discussion on the change in film strain and dielectric performance of the PLD deposited films further proved the influence of film strain on dielectric properties. We discussed the design, fabrication, and measurement of coplanar waveguide transmission lines as phase shifters fabricated BST films. The thin BST films (~700 nm) on DyScO3 substrates deposited by sputtering demonstrated that the three-step deposition technique improved differential phase shift and microwave figure of merit to a great extent. The introduction of the sputtered seed layer into the PLD deposition of a thicker BST film (~2.15 μm) showed a dramatically enhancement on differential phase shift and microwave figure of merit. The enhanced performance on different series of BST films in microwave frequencies is consistent with the improvement on crystal structure, especially with the change in film strain.

Previous research has demonstrated that behavioral skills training (BST) is effective in teaching social skills to individuals with developmental disabilities, but often the skills fail to generalize. One strategy to promote generalization has been the use of in situ training. In an effort to improve upon previous research BST plus in situ training was evaluated to teach greeting skills to adults living in a group home setting. The percentage of correct greeting responses was evaluated in a multiple baseline across participants design. Results showed that BST was only partially effective in teaching greeting skills to the participants. However, In-situ training resulted in a greater increase in correct greeting skills across all participants.

The composition-dependent Curie temperature and bias-dependant dielectric permittivity of Barium Strontium Titanate (BST) makes it very attractive for tunable application in the RF/Microwave regime. In this research work, the performance of BST varactors fabricated on the conventional Pt/Ti/SiO2/Si bottom electrode stack were compared with those fabricated using chemical vapor deposited Nanocrystalline Diamond (NCD) as the diffusion barrier layer instead of SiO2. The varactors fabricated on NCD films displayed much better symmetry in capacitance-voltage behavior and better overall quality factors than varactors fabricated on SiO2. The improvement in performance can be attributed to existence of stable interfaces in the devices fabricated on NCD which reduced the bottom electrode losses at high frequencies. The SiO2 based BST varactors on the other hand displayed better reliability and breakdown fields. The main purpose of this research work is to develop a robust Metal Insulator Metal (MIM) structure to achieve better all round performance of BST varactors. In the second part of this research work, the prospect of developing diamond based layered Surface Acoustic Wave (SAW) devices using Ba0.8Sr0.2TiO3 as the piezoelectric layer is investigated. Structural characterization of BST thin films deposited on Si/NCD/Pt and Si/SiO2/Ti/Pt stack were performed using X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM). Cross-sectional studies on the two stacks were performed using Scanning Electron Microscopy (SEM). X-Ray Mapping (XRM) was then done to ascertain the quality of the interfaces and to check for interdiffusion between layers. MIM structures in the Coplanar Waveguide (CPW) configuration were fabricated using conventional lithography and etching techniques for high frequency measurements. The performance of the fabricated varactors was characterized from 100 MHz to 1 GHz. For the SAW application, structural characterization of Ba0.8Sr0.2TiO3 on Chemical Vapor Deposited (CVD) diamond was done and the deposition procedure was optimized to obtain thick BST films. SAW bandpass filters and resonators were designed wherein the device geometry was varied over a wide range in order to characterize the variation in device performance with geometry. Finally interdigital capacitor structures were fabricated and used for conducting Curie temperature measurements on the deposited BST films in order to determine the operation range of the deposited BST films.

Interleukins, cytokines secreted by leukocytes, are predominant messengers modulating immune responses. Interleukin-27 (IL-27), a key immunomodulatory cytokine, functions to induce both pro- and anti-inflammatory effects in various immune cells. IL-27 is a heterodimeric cytokine, composed of IL-27p28 and Epstein-Bar virus induced gene 3 (EBI3) subunits, and binds to a receptor composed of IL-27Rα (WSX-1) and gp130. Initial studies focused on describing IL-27 functions in skewing T helper cell development to a Th1 response, with few reports on functions in monocytes. Thus, in this thesis, I aimed to characterize novel functions of IL-27 in innate immune responses of monocytes. I initially established that IL-27 induced a pro-inflammatory cytokine profile (IL-6, IP-10, MIP-1α, MIP-1β, and TNF-α) mediated via STAT1/3 and NF-κB signaling pathways. Further investigation led to the discovery that IL-27 could enhance LPS responses via upregulation of TLR4 expression and NF-κB signaling. Together, these studies described novel signaling mechanisms (NF-κB and JAK/STAT crosstalk) and gene targets (cytokines and TLR4) of IL-27 that drive inflammatory responses. In continuing the quest for novel IL-27 functions in innate immunity, I reported IL-27 can upregulate expression of the IFN-responsive, antiviral protein called BST-2. My results showing IL-27-induced expression of BST-2 mRNA and cell surface protein were supported by previous studies reporting IL-27-induced expression of other antiviral molecules. Furthermore, previous studies showed IL-27 could inhibit HIV replication via antiviral gene induction, pointing to potential for IL-27 immunotherapies. In light of the posited role for IL-27 in therapeutics, it became inherently critical to describe how IL-27 functions in the setting of HIV infection. Thus, in my final thesis chapters, I described the effect of HIV infection on IL-27 expression and functions, addressing a substantial void in literature. Interestingly, a trend of decreased IL-27 expression and significant impairment of IL-27-induced gene expression was observed in HIV infection. Therefore, decreased circulating IL-27 and decreased IL-27 responsiveness may collectively dysregulate IL-27 function in HIV. This thesis describes novel, IL-27-driven, proinflammatory responses, and highlights impairment of IL-27 function in HIV infection. This work bridged a gap in knowledge of IL-27 functions in monocytes and highlighted multifaceted mechanisms underlying immunoregulation by IL-27. / Thesis (Ph.D, Microbiology & Immunology) -- Queen's University, 2012-04-12 13:07:50.588