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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Problemas direto e inverso de processos de separação em leito móvel simulado mediante mecanismos cinéticos de adsorção / Direct and inverse problems of separation processes moving bed simulated by kinetic mechanisms of adsorption

Kamilla Vogas Romualdo 21 December 2012 (has links)
Diversas aplicações industriais relevantes envolvem os processos de adsorção, citando como exemplos a purificação de produtos, separação de substâncias, controle de poluição e umidade entre outros. O interesse crescente pelos processos de purificação de biomoléculas deve-se principalmente ao desenvolvimento da biotecnologia e à demanda das indústrias farmacêutica e química por produtos com alto grau de pureza. O leito móvel simulado (LMS) é um processo cromatográfico contínuo que tem sido aplicado para simular o movimento do leito de adsorvente, de forma contracorrente ao movimento do líquido, através da troca periódica das posições das correntes de entrada e saída, sendo operado de forma contínua, sem prejuízo da pureza das correntes de saída. Esta consiste no extrato, rico no componente mais fortemente adsorvido, e no rafinado, rico no componente mais fracamente adsorvido, sendo o processo particularmente adequado a separações binárias. O objetivo desta tese é estudar e avaliar diferentes abordagens utilizando métodos estocásticos de otimização para o problema inverso dos fenômenos envolvidos no processo de separação em LMS. Foram utilizados modelos discretos com diferentes abordagens de transferência de massa, com a vantagem da utilização de um grande número de pratos teóricos em uma coluna de comprimento moderado, neste processo a separação cresce à medida que os solutos fluem através do leito, isto é, ao maior número de vezes que as moléculas interagem entre a fase móvel e a fase estacionária alcançando assim o equilíbrio. A modelagem e a simulação verificadas nestas abordagens permitiram a avaliação e a identificação das principais características de uma unidade de separação do LMS. A aplicação em estudo refere-se à simulação de processos de separação do Baclofen e da Cetamina. Estes compostos foram escolhidos por estarem bem caracterizados na literatura, estando disponíveis em estudos de cinética e de equilíbrio de adsorção nos resultados experimentais. De posse de resultados experimentais avaliou-se o comportamento do problema direto e inverso de uma unidade de separação LMS visando comparar os resultados obtidos com os experimentais, sempre se baseando em critérios de eficiência de separação entre as fases móvel e estacionária. Os métodos estudados foram o GA (Genetic Algorithm) e o PCA (Particle Collision Algorithm) e também foi feita uma hibridização entre o GA e o PCA. Como resultado desta tese analisouse e comparou-se os métodos de otimização em diferentes aspectos relacionados com o mecanismo cinético de transferência de massa por adsorção e dessorção entre as fases sólidas do adsorvente. / Several important industrial applications involving adsorption processes, citing as an example the product purification, separation of substances, pollution control and moisture among others. The growing interest in processes of purification of biomolecules is mainly due to the development of biotechnology and the demand of pharmaceutical and chemical products with high purity. The simulated moving bed (SMB) chromatography is a continuous process that has been applied to simulate the movement of the adsorbent bed, in a countercurrent to the movement of liquid through the periodic exchange of the positions of input and output currents, being operated so continuous, notwithstanding the purity of the outlet streams. This is the extract, rich in the more strongly adsorbed component, and the raffinate, rich in the more weakly adsorbed component, the method being particularly suited to binary separations. The aim of this thesis is to study and evaluate different approaches using stochastic optimization methods for the inverse problem of the phenomena involved in the separation process in LMS. We used discrete models with different approaches to mass transfer. With the benefit of using a large number of theoretical plates in a column of moderate length, in this process the separation increases as the solute flowing through the bed, i.e. as many times as molecules interact between the mobile phase and stationary phase thus achieving the equilibrium. The modeling and simulation verified in these approaches allowed the assessment and identification of the main characteristics of a separation unit LMS. The application under consideration refers to the simulation of the separation of Ketamine and Baclofen. These compounds were chosen because they are well characterized in the literature and are available in kinetic studies and equilibrium adsorption on experimental results. With the results of experiments evaluated the behavior of the direct and inverse problem of a separation unit LMS in order to compare these results, always based on the criteria of separation efficiency between the mobile and stationary phases. The methods studied were the GA (Genetic Algorithm) and PCA (Particle Collision Algorithm) and we also made a hybridization between the GA and PCA. This thesis, we analyzed and compared the optimization methods in different aspects of the kinetic mechanism for mass transfer between the adsorption and desorption of the adsorbent solid phases.
22

Cromatografia continua em leito movel simulado para a purificação dos enantiomeros do N-Boc-baclofeno-lactama / Continous chromatographic in simulated moving bed to purification of enantiomers N-Boc-baclofen-lactan

Veredas, Vinícius de 18 April 2005 (has links)
Orientador: Cesar Costapinto Santana / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-09-05T13:20:08Z (GMT). No. of bitstreams: 1 Veredas_ViniciusDe_D.pdf: 13205142 bytes, checksum: 97c5009c255088bef6fcdc1fd92294c3 (MD5) Previous issue date: 2005 / Doutorado / Desenvolvimento de Processos Biotecnologicos / Mestre em Engenharia Química
23

Neuron-glial Interaction in the Developing Peripheral Nervous System

Corell, Mikael January 2011 (has links)
The nervous system, including the brain, is the most sophisticated organ in the mammalian body. In such a complex network, neuron-glial interaction is essential and controls most developmental processes, such as stem cell fate determination, migration, differentiation, synapse formation, ensheathment and myelination. Many of these events are critical for the developmental process and small errors can lead to growth retardation, malformation or disease. The understanding of the normal progress of nervous system development is fundamental and will help the discovery of new treatments for disease. This thesis discusses three types of neuron-glia interactions at different developmental stages; neural stem/progenitor cell (NSPC) differentiation, building and maintaining the structure of the sciatic nerve, and myelin formation. In Paper I we show that NSPCs, based upon their morphology and expression of specific protein markers, have the capacity to differentiate into cells of either the peripheral nervous system (PNS) or enteric nervous system (ENS) when grown with PNS or ENS primary cell cultures, or fed with conditioned medium from these. This indicates that soluble factors secreted from the PNS or ENS cultures are important for stem cell differentiation and fate determination. The adhesion protein neuronal cadherin (N-cadherin) is implicated in migration, differentiation and nerve outgrowth in the developing PNS. In Paper II N-cadherin was exclusively found in ensheathing glia (nonmyelinating Schwann cells, satellite cells and enteric glia) in contact with each other or with axons. Functional blocking of N-cadherin in dissociated fetal dorsal root ganglia (DRG) cultures led to a decrease in attachment between Schwann cells. N-cadherin-mediated adhesion of nonmyelinating Schwann cells may be important in encapsulating thin calibre axons and provide support to myelinating Schwann cells. In Paper III the inhibitory gamma aminobutyric acid (GABA) and GABAB receptors were studied in the Schwann cell of the adult sciatic nerve and DRG cultures. GABAB receptors were primarily expressed in nonmyelinating Schwann cells and protein levels decreased during development and myelination. Blocking the GABAB receptor in long-term DRG cultures led to decreased levels of mRNA markers for myelin. These results indicate that the GABA and GABAB receptors may be involved in Schwann cell myelination.
24

Cromatografia continua em leito movel simulado para a purificação dos enantiomeros do N-Boc-baclofeno-lactama / Continous chromatographic in simulated moving bed to purification of enantiomers N-Boc-baclofen-lactan

Veredas, Vinícius de 18 April 2005 (has links)
Orientador: Cesar Costapinto Santana / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-30T12:54:54Z (GMT). No. of bitstreams: 1 Veredas, Vinicius de_D.pdf: 13205142 bytes, checksum: 97c5009c255088bef6fcdc1fd92294c3 (MD5) Previous issue date: 2005 / Doutorado / Desenvolvimento de Processos Biotecnologicos / Mestre em Engenharia Química
25

Neuronal hypothalamic plasticity in chicken

Sallagundala, Nagaraja 05 April 2007 (has links)
Aufgabe der elektrophysiologischen Studie zur Charakterisierung der neuronalen hypothalamischen Plastizität beim Haushuhn war es, den Einfluss des Alters sowie GABAerger Substanzen auf die Feuerrate und die Temperatursensitivität (thermischer Koeffizient: TC) von Hypothalamusneuronen mittels extrazellulärer Ableitungen in Hirnschnitten zu untersuchen. Im Vergleich zu adulten Vögeln und Säugetieren wurde bei juvenilen Hühnern eine hohe neuronale Kältesensitivität nachgewiesen, die offensichtlich eine spezifische Eigenschaft juveniler Vögel ist. Die Ontogenese der neuronalen hypothalamischen Thermosensitivität ist deutlich artspezifisch. Einige Neurone wiesen eine inherente Kältesensitivität auf. Eine mögliche zentrale Rolle kältesensitiver Neurone im Rahmen der Thermoregulation juveniler Hühner wurde postuliert. Muscimol und Baclofen hemmen signifikant die Feuerrate der Hypothalamusneurone, unabhängig von der jeweiligen Thermosensitivität. Demgegenüber bewirken Bicucullin und CGP35348 einem Anstieg der Feuerrate. Nur bei kältesensitiven Neuronen wurde der TC signifikant durch GABAB-Rezeptor-Liganden verändert (signifikant erhöht durch Baclofen und durch CGP35348 gehemmt). Der Effekt von Muscimol und Baclofen auf Feuerrate und TC wurde durch Co-Perfusion mit einer 10-fach höheren Konzentration der entsprechenden Antagonisten Bicucullin und CGP35348 aufgehoben. Der wesentliche GABAerge Einfluss auf thermosensitive und –insensitive Hypothalamusneurone ist mit dem bei Säugetieren nachgewiesenen vergleichbar. Der einzige Unterschied betrifft die GABAB-Rezeptor vermittelte Änderung des TC. Beim Hühnerküken betraf dies die kältesensitiven und beim Säugetier die wärmesensitiven Neurone. Der grundlegende Mechanismus der GABAergen Beeinflussung thermosensitiver und –insensitiver Neurone scheint einen älteren evolutionären Ursprung zu haben. Eine funktionelle Rolle GABAerger Substanzen im Rahmen der zentralen Kontrolle der Körpertemperatur beim Vogel ist möglich. / In the present electrophysiological studies, characterization of neuronal hypothalamic plasticity in the chicken aims to investigate the influence of age during development by extracellular recordings. High neuronal cold sensitivity has been found in juvenile chicken in contrast to adult mammals and birds. High hypothalamic cold sensitivity seems to be a specific characteristic feature in juvenile birds. Between species a species specificity of the early development of neuronal hypothalamic thermosensitivity could be clearly demonstrated. Existence of inherent nature to a certain degree suggests a possible thermoregulatory role of cold-sensitive neurons in chicken. The effects of the GABAergic substances on neuronal tonic activity (firing rate) and temperature sensitivity (temperature coefficient) in hypothalamic neurons have been examined. Muscimol and baclofen in equimolar concentrations significantly inhibited tonic activity, regardless of their type of thermosensitivity. In contrast bicuculline and CGP 35348 increased firing rate. Temperature coefficient was significantly changed by ligands of GABAB receptors, restricted to cold-sensitive neurons. The TC was significantly increased by baclofen and significantly decreased by CGP 35348. Effects of muscimol and baclofen on firing rate and TC were prevented by co-perfusion of appropriate antagonists bicuculline and CGP 35348, respectively in tenfold higher concentration. Thus the main effects of GABA in chicken are similar with that described in mammals. The only difference is in respect of the GABAB receptors mediated change restricted to cold-sensitive neurons in chicken but in mammals only seen in warm-sensitive neurons. However, the results indicate that the fundamental mechanism of GABAergic influence in chicken are conserved during evolution. The response of hypothalamic neurons to temperature changes suggest a possible functional role of GABAergic substances in the control of body temperature in birds.
26

Intra-nucleus accumbens shell injections of R(+)- and S(-)- baclofen bidirectionally alter binge-like ethanol, but not saccharin, intake in C57Bl/6J mice

Kasten, Chelsea Rae January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / It has been proposed that the GABAB receptor subtype plays a role in alcoholism and alcohol use disorders (AUDs) (Cousins et al., 2002; Agabio et al., 2012). Specifically, the GABAB agonist baclofen has been looked at extensively in clinical and pre-clinical studies. In various animal models of chronic and intermittent consumption, baclofen has been shown to both increase (Petry, 1997; Smith et al., 1999; Czachowski et al., 2006; Moore et al., 2007) and decrease (Colombo et al., 2000; 2002; 2005; Stromberg, 2004; Moore et al., 2009) drinking. A critical issue in determining pharmacological effects of a drug is using the appropriate animal model. The drinking-in-the-dark (DID) model, developed by Rhodes et al. (2005, 2007), produces high levels of drinking in a binge-like paradigm and has been used to assess many pharmacological targets (e.g. Kamdar et al., 2007; Gupta et al., 2008; Moore et al., 2007; 2009). While DID produces high-levels of binge drinking, it is unclear what areas of the brain are involved in this behavior. A direct way to target areas that are believed to be involved in the circuitry of particular behaviors is through microinjection of drugs (Kiianmaa et al., 2003). Of particular recent interest involving motivated behaviors and addiction is the nucleus accumbens (Acb) (Everitt & Robbins, 2005); specifically the accumbens shell (AcbSh) (e.g. Rewal et al., 2009, 2012; Nie et al., 2011; Leriche et al., 2008). The current study aimed to investigate the role of GABAB receptors in the AcbSh by examining the ability of two different enantiomers of baclofen to alter ethanol and saccharin intake in male C57BL/6J (B6) mice. B6 mice underwent bilateral cannulation surgery targeting the AcbSh. After 48 hours of recovery time, animals began a five day Drinking-in-the-Dark (DID) procedure where they received 20% ethanol or 0.2% saccharin for two hours, three hours into the dark cycle, each day. Throughout the five drinking sessions, animals were kept in home-cage locomotor activity chambers to monitor activity throughout the drinking cycle. Day 4 drinking was immediately preceded by a mock microinjection, whereas Day 5 drinking was immediately preceded by a drug microinjection. Microinjection of one of five doses of baclofen was given in ng/side dissolved in 200 µl of aCSF (aCSF alone, 0.02 R(+)-, 0.04 R(+)-, 0.08 S(-)-, or 0,16 S(-)-). Intake was recorded every twenty minutes on Days 4 and 5. Retro-orbital sinus blood samples were taken from ethanol animals immediately following the Day 5 drinking period to determine blood ethanol concentrations (BECs). A one-way ANOVA on total Day 4 ethanol consumption revealed no baseline differences between dose groups. A one-way ANOVA on total Day 5 ethanol consumption revealed that the 0.04 R(+)- baclofen dose reduced total drinking, but the 0.16 S(-)- baclofen dose increased total drinking (p’s<0.05). This pattern was reflected in the BECs; 0.04 R(+)- baclofen reduced BECs, whereas 0.16 S(-)- baclofen increased BECs (p’s<0.05). These results were also time-dependent, with R(+)-baclofen reducing drinking in the first 20 minutes of the session and S(-)- increasing drinking in the last 40 minutes of the session. There were no effects on saccharin intake. An issue with the locomotor activity boxes led to unreliable locomotor activity counts. However, because there were no drug effects on saccharin consumption, it was concluded that locomotor effects did not contribute to the decreases or increases in ethanol consumption. These results further implicate the role of GABAB receptors in modulating ethanol intake. The bidirectional effects shown highlight the importance of considering enantioselective drug effects when interpreting data. Finally, these results also support previous conclusions that the AcbSh plays an important role in modulating use of drugs of abuse, but not other reinforcers.

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