Thesis (Ph. D. in Chemical Engineering)--Vanderbilt University, Aug. 2005. / Title from title screen. Includes bibliographical references.

Volatile emissions from Cascades cinder cone eruptions have been well-documented; however the implications for understanding the effects that volcanic gases have on surrounding communities have not been addressed. This study examines the hazards from volatile degassing during explosive activity by (1) analyzing S, Cl, and F concentrations dissolved in olivine-hosted melt inclusions and matrix glass from cinder cones located in central Oregon and northern California, (2) estimating the mass of volcanic gas degassed during these eruptions, and (3) predicting gas concentrations downwind of the vent. Analyses reveal that the magmas degassed >88% S, <49% Cl, and <50% F during eruption, equating to a release of ≤4.5 Mt SO2, ≤0.2 Mt HCl, and ≤0.2 Mt HF. Predictions of gas concentrations downwind of the vent provides reassurance that the levels of volcanic gases were not high enough at the time of eruption to present acute or severe health hazards to nearby residents.

abstract: Volcanic devolatilization is one of the major processes in the global nitrogen cycle. Past studies have often estimated the magnitude of this flux using volcanic emission measurements, which are limited to currently active systems and sensitive to atmospheric contamination. A different methodological approach requires appropriate analytical parameters for nitrogen analysis in silicate glasses by secondary ion mass spectrometry (SIMS), which have not yet been established. To this end, we analyze various ion implanted basaltic and rhyolitic glasses by SIMS. We demonstrate that water content significantly affects the ion yields of 14N+ and 14N16O−, as well as the background intensity of 14N+ and 12C+. Application of implant-derived calibrations to natural samples provide the first reported concentrations of nitrogen in melt inclusions. These measurements are from samples from the Bishop Tuff in California, the Huckleberry Ridge Tuff of the Yellowstone Volcanic Center, and material from the Okaia and Oruanui eruptions in the Taupo Volcanic Center. In all studied material, we find maximum nitrogen contents of less than 45 ppm and that nitrogen concentration varies positively with CO2 concentration, which is interpreted to reflect partial degassing trend. Using the maximum measured nitrogen contents for each eruption, we find that the Bishop released >3.6 x 1013 g of nitrogen, the Huckleberry Ridge released >1.3 x 1014 g, the Okaia released >1.1 x 1011 g of nitrogen, the Oruanui released >4.7 x 1013 g of nitrogen. Simple calculations suggest that with concentrations such as these, rhyolitic eruptions may ephemerally increase the nitrogen flux to the atmosphere, but are insignificant compared to the 4 x 1021 g of nitrogen stored in the atmosphere. / Dissertation/Thesis / Masters Thesis Geological Sciences 2016

abstract: Non-volatile memories (NVM) are widely used in modern electronic devices due to their non-volatility, low static power consumption and high storage density. While Flash memories are the dominant NVM technology, resistive memories such as phase change access memory (PRAM) and spin torque transfer random access memory (STT-MRAM) are gaining ground. All these technologies suffer from reliability degradation due to process variations, structural limits and material property shift. To address the reliability concerns of these NVM technologies, multi-level low cost solutions are proposed for each of them. My approach consists of first building a comprehensive error model. Next the error characteristics are exploited to develop low cost multi-level strategies to compensate for the errors. For instance, for NAND Flash memory, I first characterize errors due to threshold voltage variations as a function of the number of program/erase cycles. Next a flexible product code is designed to migrate to a stronger ECC scheme as program/erase cycles increases. An adaptive data refresh scheme is also proposed to improve memory reliability with low energy cost for applications with different data update frequencies. For PRAM, soft errors and hard errors models are built based on shifts in the resistance distributions. Next I developed a multi-level error control approach involving bit interleaving and subblock flipping at the architecture level, threshold resistance tuning at the circuit level and programming current profile tuning at the device level. This approach helped reduce the error rate significantly so that it was now sufficient to use a low cost ECC scheme to satisfy the memory reliability constraint. I also studied the reliability of a PRAM+DRAM hybrid memory system and analyzed the tradeoffs between memory performance, programming energy and lifetime. For STT-MRAM, I first developed an error model based on process variations. I developed a multi-level approach to reduce the error rates that consisted of increasing the W/L ratio of the access transistor, increasing the voltage difference across the memory cell and adjusting the current profile during write operation. This approach enabled use of a low cost BCH based ECC scheme to achieve very low block failure rates. / Dissertation/Thesis / Ph.D. Electrical Engineering 2014

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O 1,8-cineol, o &#945;-pineno e &#946;-pineno sÃo monoterpenos constituintes do Ãleo essencial de plantas encontradas no Nordeste do Brasil como a âmalva-santaâ e o âeucaliptoâ (Ãleo Essencial do Eucalyptus tereticornis - OEET) que, na medicina popular, sÃo usadas no tratamento de distÃrbios intestinais e respiratÃrios. As aÃÃes miorrelaxantes desses Ãleos essenciais sÃo atribuÃdas à presenÃa desses monoterpenos. Nosso objetivo foi estudar mais detalhadamente os efeitos desses constituintes, assim como o do OEET, sobre a contratilidade do mÃsculo liso gastrintestinal e sobre o efeito procinÃtico em ratos. No presente estudo, foram usados ratos Wistar machos (180-250g) sacrificados por deslocamento cervical. Tiras de duodeno, Ãleo e fundo de estÃmago foram cortados e mantidos em soluÃÃo de Tyrode normal. As contraÃÃes isomÃtricas foram registradas atravÃs de transdutores de forÃa conectados a sistema computadorizado. SoluÃÃes contendo o 1,8-cineol, o &#945;-pineno ou &#946;-pineno foram preparadas em Tween 80 (concentraÃÃo final &#8804; 0,2% v/v). Usados isoladamente, o OEET, o 1,8-cineol, o &#945;-pineno e &#946;-pineno diminuÃram o tÃnus basal em tiras de duodeno. Em tÃnus basal de tiras isoladas de fundo gÃstrico, o OEET e o 1,8-cineol possuÃram efeito miorrelaxante, enquanto o &#945;-pineno e o &#946;-pineno possuÃram efeito contrÃtil. Esse efeito contrÃtil do &#945;-pineno e do &#946;-pineno em tiras isoladas de fundo gÃstrico à por possÃvel interferÃncia com o mecanismo dependente de IP3 e independe da ativaÃÃo local do receptor muscarÃnico e de uma aÃÃo central na ativaÃÃo de receptores nicotÃnicos, da mesma forma, o efeito miorrelaxante na musculatura lisa duodenal à mediado por possÃvel interferÃncia com os mecanismos celulares mediados pela formaÃÃo de IP3. AlÃm disso, como demonstrado anteriormente, em Ãleo de rato, esses monoterpenos provavelmente ativam as vias de entrada de Ca2+ para a cÃlula em situaÃÃes de depleÃÃo dos estoques intracelulares. Em estudos de retenÃÃo fracional de corante no trato gastrintestinal, o OEET, o 1,8-cineol, o &#945;-pineno e o &#946;-pineno promoveram a aceleraÃÃo do esvaziamento gÃstrico. O &#945;-pineno e &#946;-pineno tambÃm aceleraram o trÃnsito intestinal e reduziram a complacÃncia gÃstrica. Os nossos dados mostram que OEET possui propriedades prÃ-cinÃticas, que podem ser atribuÃveis aos efeitos contrastantes induzidos por &#945;-pineno e &#946;-pineno, corroborando com dados apresentados anteriormente (JucÃ, 2007). / The monoterpenes 1,8-cineole, &#945;-pinen and &#946;-pinene are constituents commonly found in several essential oils obtained from plants in Brazilian northeast such as âmalva-santaâ and âeucaliptoâ (Essential Oil of Eucalyptus tereticornis - EOET), which are used in folk medicine to treat respiratory and gastrointestinal dysfunctions. Myorelaxant actions are due to the presence of these constituents in their essential oils. The present work aimed to further study the pharmacological effects of these compounds, as well as the EOET, on smooth muscle gastrointestinal contractility and the prokinetic effect in rats. Wistar rats (200-250 g) were used, sacrificed by cervical dislocation. Strips were carefully obtained from gastric fundus, duodenum and ileum, and were maintained in normal Tyrode&#8223;s solution. Isometric contractions were recorded through force transducers coupled to a computerized data acquisition system. Solutions containing 1,8-cineolo, &#945;-pinene or &#946;-pinene were prepared with Tween 80 (final concentration &#8804; 0,2% v/v). Solely used, EOET, 1,8-cineole, &#945;-pinene or &#946;-pinene decreased duodenal basal tonus. In basal tone of gastric fundus isolated strips, EOET and 1,8-cineole had relaxant effect, while &#945;-pinene and &#946;-pinene had contractile effect. This contractile effect of &#945;-pinene and &#946;-pinene in isolated strips of gastric fundus is due to possible interference with IP3-dependent mechanism and independent of the muscarinic receptor activation and a central action in the activation of nicotinic receptors, in the same way, the duodenal smooth muscle relaxant effect is mediated by possible interference with the cellular mechanisms mediated by the formation of IP3. Moreover, as shown above, in the rat ileum, monoterpenes activate capacitative Ca2+ entry to intracellular milieu after Ca2+ stores depletion. The &#945;-pinene and &#946;-pinene also accelerated intestinal transit and reduced gastric compliance. Our data show that OEET has prokinetic properties in rats, which may be attributable to the contrasting effects induced by &#945;-pinene and &#946;-pinene, corroborating data presented previously (JucÃ, 2007).

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / AntipsicÃticos representam o alicerce no tratamento da esquizofrenia, um transtorno mental grave, incapacitante, com elevada carga social. A esquizofrenia à uma sÃndrome caracterizada pela presenÃa de sintomas positivos, negativos e cognitivos. A terapia atual nÃo trata de maneira satisfatÃria os sintomas negativos e cognitivos. Um modelo relevante para o estudo da esquizofrenia em uma abordagem prÃ-clÃnica à o da administraÃÃo de cetamina. Neste sentido a administraÃÃo repetida desta droga à capaz de mimetizar grande parte dos sintomas da esquizofrenia em roedores. A Alpinia zerumbet à uma planta cujo Ãleo essencial (OEAZ) vem apresentando importante efeito antipsicÃtico como evidenciado em publicaÃÃes prÃvias de nosso grupo de pesquisa. Com base nesta afirmativa o presente trabalho objetivou determinar os efeitos do OEAZ contra sintomas positivos, negativos e cognitivos tipo esquizofrenia induzidos pela administraÃÃo aguda e repetida de cetamina. Para tanto foram utilizados ratos Wistar machos tratados com OEAZ 100 ou 200 mg/kg sozinho ou apÃs a administraÃÃo de cetamina. No protocolo de administraÃÃes repetidas a cetamina foi administrada por cinco dias e por mais cinco dias os animais receberam cetamina e OEAZ 100 ou 200 mg/kg. Um grupo de animais foi tratado com o antipsicÃtico atÃpico risperidona e outro recebeu soluÃÃo salina (controle). ApÃs os tratamentos os animais foram submetidos a avaliaÃÃes comportamentais para a determinaÃÃo de sintomas positivos (atividade locomotora), negativos (interaÃÃo social) e cognitivos (labirinto em Y e memÃria de reconhecimento de objetos). Os resultados mostraram que a administraÃÃo aguda de cetamina nÃo foi capaz de causar alteraÃÃes em todos os modelos utilizados, principalmente em relaÃÃo à memÃria de reconhecimento de objetos que foi inclusive melhorada pela administraÃÃo aguda da droga. O OEAZ em ambas as doses foi capaz de reverter estas alteraÃÃes. A administraÃÃo repetida da cetamina foi capaz de mimetizar de forma mais fiel as alteraÃÃes relacionadas à esquizofrenia, sendo que neste modelo a administraÃÃo do OEAZ foi superior à da risperidona, principalmente na memÃria de trabalho. Portanto, os resultados do presente estudo mostram que o OEAZ pode ser uma nova abordagem farmacolÃgica no tratamento dos sintomas negativos e cognitivos da esquizofrenia / Antipsychotics represent the basis in treatment of schizophrenia, a severe mental disorder, disabling, with high social burden. Schizophrenia is a syndrome characterized by the presence of positive, negative and cognitive symptoms. The current therapy does not manage satisfactorily the negative and cognitive symptoms. One of the most relevant models for the study of schizophrenia in a preclinical approach is the administration of ketamine. In this sense the repeated administration of the drug can largely mimic the symptoms of schizophrenia in rodents. The Alpinia zerumbet is a plant whose essential oil (EOAZ) has shown significant antipsychotic effect as evidenced in previous studies of our research group. Based on this statement the present study aimed to determine the effects of EOAZ against positive, negative and cognitive schizophrenia induced by acute and repeated administration of ketamine-like symptoms. For this it was used male Wistar rats treated with EOAZ 100 or 200 mg/kg alone or following the administration of ketamine. In repeated administration protocol ketamine was applied for five days and in the subsequent five days the animals received both ketamine and EOAZ 100 or 200 mg/kg. One group of animals was treated with the atypical antipsychotic risperidone and other received saline (control). After treatment the animals were subjected to behavioral assessments for the determination of positive symptoms (locomotor activity) , negative (social interaction) and cognitive (Y maze and object recognition memory) . The results showed that acute administration of ketamine was not able to cause changes in all models used , especially in relation to recognition memory of objects that was even enhanced by acute drug administration. The EOAZ at both doses was able to reverse those changes. Repeated administration of ketamine was able to mimic more accurately the changes related to schizophrenia , and in this model the administration of EOAZ was superior to risperidone , particularly in working memory. Therefore, the results of this study show that EOAZ may be a new pharmacological approach in treating negative and cognitive symptoms of schizophrenia.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A doenÃa tuberculose à altamente infecciosa e estima-se que um terÃo da populaÃÃo mundial esteja infectada. Em 2012, foi estimado que 8,6 milhÃes de pessoas no mundo tiveram a doenÃa, representando umas das doenÃas infecciosas que mais matam no mundo. O agente causador da infecÃÃo à o Mycobacterium tuberculosis, uma micobactÃria com alta capacidade de adquirir resistÃncia aos fÃrmacos usados no tratamento. O desenvolvimento de novas drogas ou opÃÃes terapÃuticas com atividade antimicobacteriana se faz necessÃrio para a reduÃÃo da prevalÃncia da doenÃa. As plantas atravÃs de vias metabÃlicas secundÃrias produzem diversos compostos, sendo jà verificada atividade biolÃgica contra micobactÃrias em algumas classes de terpenÃides. Este estudo avaliou a atividade antimicobacteriana de Ãleos essenciais de Lippia alba, Lippia sidoides, Cymbopogon citratus, Plectranthus amboinicus e Cinnamomun zeylanicum contra a cepa padrÃo (H37Rv) de M. tuberculosis. A tÃcnica utilizada foi de microdiluiÃÃo em placa de 96 poÃos (Resazurin Microtiter Assay - REMA), onde se utiliza a rezasurina, indicador de oxirreduÃÃo, para a avaliaÃÃo do crescimento bacteriano. O rendimento da extraÃÃo dos Ãleos de L. alba, L. sidoides, C. citratus, P. amboinicus e C. zeylanicum foi de 0,49%, 0,68%, 0,30%, 0,009% e 0,13%, respectivamente. O citral foi encontrado como o principal constituinte dos Ãleos de L. alba (70,6%) e C. citratus (80,7%). O Ãleo de L. sidoides teve como principal constituinte o cariofileno (30,2%). O timol (64,3%) foi encontrado em maior percentual de concentraÃÃo no Ãleo do P. amboinicus. No Ãleo de C. zeylanicum foi encontrado o trans-cinamaldeÃdo (86,0%) como principal constituinte. O Ãleo essencial de L. alba nÃo apresentou atividade antimicobacteriana. Os Ãleos de L. sidoides, C. citratus, P. amboinicus e C. zeylanicum apresentaram CIM de 299,5Â117,2Âg/ml, 1.250Âg/ml, 351,6Â55,2Âg/ml e 286,5Â130,2Âg/ml, respectivamente. O Ãleo que apresentou maior atividade antimicobacteriana foi o de L. sidoides, com potÃncia de 5,4 x 10-4. Os resultados mostram que os Ãleos essenciais de L. sidoides, C. citratus, P. amboinicus e C. zeylanicum, contÃm substÃncias com propriedades de inibiÃÃo do crescimento da cepa padrÃo H37Rv de M. tuberculosis. Os Ãleos essenciais sÃo alternativas promissoras na descoberta de novos agentes terapÃuticos. / The infectious agent is the Mycobacterium tuberculosis, one mycobacteria with high capacity to acquire resistance to agents used in the treatment. The development of new drugs or treatments with antimicrobial activity is necessary for reducing the prevalence of the disease. Plants through secondary metabolic pathways produce various compounds, being already observed biological activity against mycobacteria in some classes of terpenoids. This study evaluated the antimicrobial activity of essential oils from Lippia alba, Lippia sidoides, Cymbopogon citratus, Plectranthus amboinicus and Cinnamomun zeylanicum against standard strain (H37Rv) of M. tuberculosis. The technique used was in 96-well microdilution (Resazurin Microtiter Assay - REMA) card, which uses the rezasurina, redox indicator for the evaluation of the bacterial growth. The yield of extraction of oils from L. alba, L. sidoides, C. citratus, P. amboinicus and C. zeylanicum was 0.49%, 0.68%, 0.30%, 0.009% and 0.13%, respectively. Citral was found as the major constituent of oil of L. alba (70.6%) and C. citratus (80.7%). The oil of L. sidoides has as the main constituent the caryophyllene (30.2%). The thymol (64.3%) was found in a higher percentage of oil concentration in P. amboinicus. In the oil of C. zeylanicum the trans-cinnamaldehyde (86.0%) was found as the main constituent. The essential oil of L. alba do not showed antimicrobial activity. The oil of L. sidoides, C. citratus, P. amboinicus and C. zeylanicum showed MIC of 299.5Â117.2mg/ml, 1.250&#956;g/ml, 351.6Â55.2mg/ml and 286.5Â130.2g/ml, respectively. The oil that showed higher antimicrobial activity was the of L. sidoides, with power of 5.4 x 10-4. The results show that essential oils of L. sidoides, C. citratus, P. amboinicus and C. zeylanicum contains substances with properties of inhibiting the growth of the standard strain H37Rv of M. tuberculosis. Essential oils are promising alternatives in the discovery of new therapeutic agents.

No description available.

Noble gas and halogen data from a suite of Icelandic samples are presented. Iceland combines hotspot volcanism, a spreading ridge and abundant subglacially erupted samples. This combination allows for samples that erupted under high enough pressures to retain a measurable mantle volatile content, and also display signatures representing interaction between ocean island basalt (OIB) and mid-ocean ridge basalt (MORB) mantle sources.Erupted samples used to determine the mantle’s halogen and noble gas content have undergone a degassing process that can alter their volatile composition. An existing disequilibrium degassing model is developed with the modified model taking into account the evolution of the major volatiles over a multi-stage process and the different conditions present during magma ascent and quenching. The modified model allows substantially lower elemental noble gas ratios to be reached under disequilibrium conditions than allowed by the original model. Initial CO2 concentrations, pressure, diffusivity, ascent rate and degree of disequilibrium are shown to be critical parameters for this model. Final degassed noble gas concentrations are most affected by the surface quenching stage of an eruption, whereas noble gas elemental ratios can be primarily determined during magma ascent. In applying this model to MORB and OIB sample suites, the 3He/22Ne ratio of the MORB source mantle is constrained to be lower than 4.4, similar to estimates for the OIB source mantle. Additionally the most straightforward match between the degassing model and OIB helium and neon data suggest the OIB source mantle has 3He concentrations similar to or lower than the MORB source mantle. This finding requires a model for the OIB source mantle in which a high 3He/4He component is added to a helium-poor protolith.Noble gas studies are hampered by the large, isotopically atmospheric component typically found in Icelandic subglacial samples, which can swamp other signatures. Detailed analysis of a volatile rich sample from SW Iceland shows evidence for more than one ‘contaminant’ component and that two component fits used incorrectly can produce misleadingly precise source mantle noble gas ratios. Multi component best fits to noble gas elemental ratios find that four components are present in samples from this region. These components are unfractionated air, fractionated air and a mantle component which shows some variation due to degassing. Combining the disequilibrium degassing model with component resolution allows limits to be placed on the source mantle composition for this sample. The light noble gas source composition is compatible with mixing between a solar (‘direct nebula’) component and a MORB-like component. This direct nebula signature is at odds with an implanted signature seen in both Ne and Kr for the convecting mantle, and shows that both accretionary volatile origins must have contributed during the Earth’s formation. The heavy noble gases show an elemental abundance pattern which is distinct from air and solar patterns, and trends towards seawater. This confirms the presence of a recycled volatile signature in Iceland’s mantle but it is not possible to further constrain the origin of this signature.The Icelandic halogen data shows no evidence for significant fractionation during degassing or melt generation. Source estimates for the Br/Cl and I/Cl ratios for Iceland’s plume are found to be (1.56±0.03) x 10-3 and (3.1±0.3) x 10-5, compatible with estimates for the MORB source mantle. Halogen source concentrations in central Iceland are found to be approximately three times higher than estimates for the convecting mantle and correlate with the regions of Iceland that show high 3He/4He ratios and high source water contents. This may indicate a recycled halogen signature associated with Iceland’s proposed mantle plume.

Geochemical measurements of OIB (ocean island basalt) samples have demonstrated that the Earth's mantle is compositionally heterogeneous, but the cause of this heterogeneity is a point of debate within the scientific community. One such OIB location is Mangaia, Cook Islands (Polynesia). Its lead isotopic composition defines the HIMU (high μ = high ^238U/^204Pb) mantle endmember, which many attribute to recycled oceanic crust being present in the mantle source. If true, this endmember represents an important vehicle for returning surface material to the mantle and an opportunity to study volatile element cycling through the mantle. Sulfur isotopic measurements were made on sulfides hosted in melt inclusions from Mangaia. Prior to 2.45 Ga, the Earth's atmosphere was not oxygenated, allowing photochemical cycles to fractionate sulfur isotopes. This form of fractionation results in a mass independently fractionated (MIF) sulfur isotopic signature in surface materials containing sulfur. We have found such a signal in sulfide inclusions from Mangaia, indicating that the material erupted at this young (~19 Ma) ocean island was once at the surface over 2.45 Ga. This finding confirms the recycled origin hypothesis for the generation of the HIMU mantle endmember. Lead isotopes and major elements were measured in olivine hosted melt inclusions from the island. Previous studies by Saal et al. (1998) and Yurimoto et al. (2004) have revealed large lead isotopic variability, spanning half of the global range for OIBs. A more recent study by Paul et al. (2011) has shown much reduced lead isotopic variability using a different analysis technique. We find the lead isotopic variability in glassy melt inclusions to be less than previously found and attribute much of the earlier observed variability to contaminant lead. Volatile and trace elements were measured in the same olivine hosted melt inclusions, providing the first ever coupled lead isotopes, major, trace, and volatile elements in glassy melt inclusions from the island. We observe some of the highest water and carbon dioxide contents found in OIBs globally. This allows us to constrain volatile abundances in the HIMU mantle source as well as volatile cycling in the mantle, from subduction zones to hotspots.