Magnetic and petrographic properties of ODP Site 120-747 (Table 1)

Carbonate sediments from the Kerguelen Plateau (ODP Leg 120) of Eocene to Pliocene age were investigated with rock magnetic, petrographic and geochemical methods to determine the carriers of remanent magnetization. Magnetic methods showed that the major magnetic minerals were titanomagnetites slightly larger than single domain particles. Submicrometre to micrometre-size grains of titanomagnetite were identified as inclusions in volcanic glass particles or as crystals in lithic clasts. Volcanic fallout ash particles formed the major fraction of the magnetic extract from each sediment sample. Three groups of volcanic ashes were identified: trachytic ashes, basaltic ashes with sideromelane and tachylite shards, and palagonitic ashes. These three groups could be equally well defined based on their magnetic hysteresis properties and alternating field demagnetization curves. The highest coercivities of all samples were found for the tachylite, due to the submicrometre-size titanomagnetite inclusions in the matrix. Trachytic ashes had intermediate magnetic properties between the single-domain-type tachylites and the palagonitic (altered) basaltic ashes with low coercivities. Samples which contained mixtures of these different volcanic ashes could be distinguished from the three types of ashes based on their magnetic characteristics. There was neither evidence of biogenic magnetofossils in the transmission electron micrographs nor did we find magnetic particles derived from continental Antarctica. The presence of dispersed volcanic fallout ashes between visible ash layers suggests continuous explosive volcanic activity on the Kerguelen Plateau in the South Indian Ocean since the early Eocene. The continuous fallout of volcanic ash from explosive volcanism on the Kerguelen Archipelago is the source of the magnetic particles and thus responsible for the magnetostratigraphy of the nannofossil oozes drilled during Leg 120.

Three-dimensional simulations of gravitationally confined detonations compared to observations of SN 1991T

The gravitationally confined detonation (GCD) model has been proposed as a possible explosion mechanism for Type Ia supernovae in the single-degenerate evolution channel. It starts with ignition of a deflagration in a single off-centre bubble in a near-Chandrasekhar-mass white dwarf. Driven by buoyancy, the deflagration flame rises in a narrow cone towards the surface. For the most part, the main component of the flow of the expanding ashes remains radial, but upon reaching the outer, low-pressure layers of the white dwarf, an additional lateral component develops. This causes the deflagration ashes to converge again at the opposite side, where the compression heats fuel and a detonation may be launched. We first performed five three-dimensional hydrodynamic simulations of the deflagration phase in 1.4 M⊙ carbon/oxygen white dwarfs at intermediate-resolution (2563computational zones). We confirm that the closer the initial deflagration is ignited to the centre, the slower the buoyant rise and the longer the deflagration ashes takes to break out and close in on the opposite pole to collide. To test the GCD explosion model, we then performed a high-resolution (5123 computational zones) simulation for a model with an ignition spot offset near the upper limit of what is still justifiable, 200 km. This high-resolution simulation met our deliberately optimistic detonation criteria, and we initiated a detonation. The detonation burned through the white dwarf and led to its complete disruption. For this model, we determined detailed nucleosynthetic yields by post-processing 106 tracer particles with a 384 nuclide reaction network, and we present multi-band light curves and time-dependent optical spectra. We find that our synthetic observables show a prominent viewing-angle sensitivity in ultraviolet and blue wavelength bands, which contradicts observed SNe Ia. The strong dependence on the viewing angle is caused by the asymmetric distribution of the deflagration ashes in the outer ejecta layers. Finally, we compared our model to SN 1991T. The overall flux level of the model is slightly too low, and the model predicts pre-maximum light spectral features due to Ca, S, and Si that are too strong. Furthermore, the model chemical abundance stratification qualitatively disagrees with recent abundance tomography results in two key areas: our model lacks low-velocity stable Fe and instead has copious amounts of high-velocity 56Ni and stable Fe. We therefore do not find good agreement of the model with SN 1991T.

Evaluation of the Chemical Durability of Iowa Fly Ash Concretes, HR-327, Phase II Progress Report, 1992

The major objective of this research project is to investigate how fly ash influences the chemical durability of portland cement based materials. The testing program is evaluating how Iowa fly ashes influence the sulfate durability of portland cement-fly ash pastes, mortars, and concretes. Also, alkali-reactivity studies are being conducted on mortar bar specimens prepared in accordance with ASTM C 311. Prelimary sulfate test results, based only on mortar bar studies, indicate that only the very high-calcium fly ash (29 percent CaO, by weight) consistently reduced the durability of test specimens exposed to a solution containing 5 percent sodium sulfate. The remaining four fly ashes that were used in the study showed negligible to dramatic increases in sulfate resistance. Concrete specimens were only beginning to respond to the sulfate solutions after about one year of exposure; and hence, considerably more time will be needed to assess their performance. Preliminary results from the alkali-reactivity tests have indicated that the Oreopolis aggregate is not sensitive to alkali attack. However, some of the test results have indicated that the testing procedure may be prone to delayed expansion due to the presence of periclase (MgO) in the Class C fly ashes. Research is being planned to: (1) verify if the periclase is influencing test results; and (2) estimating the magnitude of the potential error.

Impacts des dépositions atmosphériques de fer sur les assemblages phytoplanctoniques et la production de diméthylsulfure dans le Pacifique Nord-Est contemporain et dans le contexte de l’acidification des océans

La croissance du phytoplancton est limitée par les faibles concentrations de fer (Fe) dans près de 40% de l’océan mondial. Le Pacifique subarctique Nord-Est représente une de ces zones limitées en fer et désignées High Nutrient - Low Chlorophyll (HNLC). Cet écosystème, dominé par des cellules de petite taille telles les prymnésiophytes, est caractérisé par de très faibles concentrations estivales de chlorophylle a et de fortes concentrations de macronutriments. Il a été maintes fois démontré que les ajouts de fer, sous différentes formes chimiques (habituellement FeSO4), dans les zones HNLC, stimulent la croissance et modifient la structure des communautés planctoniques en favorisant la croissance des cellules de grande taille, notamment les diatomées. Ces effets sur la communauté planctonique ont le potentiel d’influencer les grands mécanismes régulateurs du climat, tels la pompe biologique de carbone et la production de diméthylsulfure (DMS). Les poussières provenant des déserts du nord de la Chine sont reconnues depuis longtemps comme une source sporadique importante de fer pour le Pacifique Nord-Est. Malgré leur importance potentielle, l’influence directe exercée par ces poussières sur l’écosystème planctonique de cette zone HNLC n’a jamais été étudiée. Il s’agit d’une lacune importante puisque le fer associé aux poussières est peu soluble dans l’eau de mer, que la proportion biodisponible n’est pas connue et que les poussières peuvent avoir un effet inhibiteur chez le phytoplancton. Cette thèse propose donc, dans un premier temps, de mesurer pour la première fois l’effet de la fertilisation de la communauté planctonique du Pacifique Nord-Est par un gradient de concentrations de poussières désertiques naturelles. Cette première expérimentation a démontré que le fer contenu dans les poussières asiatiques est biodisponible et qu’une déposition équivalente à celles prenant place au printemps dans le Pacifique Nord-Est peut résulter en une stimulation significative de la prise de nutriments et de la croissance du phytoplancton. Mes travaux ont également montré que l’ajout de 0,5 mg L-1 de poussières peut résulter en la production d’autant de biomasse algale que l’ajout de FeSO4, l’espèce chimique utilisée lors des expériences d’enrichissement en fer à grande échelle. Cependant, les ajouts de FeSO4 favorisent davantage les cellules de petite taille que les ajouts de poussières, observation démontrant que le FeSO4 n’est pas un proxy parfait des poussières asiatiques. Dans un deuxième temps, je me suis intéressée à une source alternative de fer atmosphérique, les cendres volcaniques. Mon intérêt pour cette source de fer a été attisé par les observations d’une floraison spectaculaire dans le Pacifique Nord-Est, ma région d’étude, associée à l’éruption de 2008 du volcan Kasatochi dans les îles Aléoutiennes. Forte de mon expérience sur les poussières, j’ai quantifié l’effet direct de ces cendres volcaniques sur la communauté planctonique du Pacifique Nord-Est. Mes résultats ont montré que le fer contenu dans les cendres volcaniques est également biodisponible pour le phytoplancton. Ils ont également montré que cette source de fer peut être aussi importante que les poussières désertiques dans la régulation de la croissance du phytoplancton dans cette partie de l’océan global à l’échelle millénaire. Dans un troisième temps, j’ai estimé comment l’acidification des océans modulera les réponses des communautés planctoniques aux dépositions naturelles de fer mises en évidence lors de mes expériences précédentes. Pour ce faire, j’ai effectué des enrichissements de poussière dans de l’eau de mer au pH actuel de 8.0 et dans l’eau de mer acidifiée à un pH de 7.8. Mes résultats ont montré une diminution du taux de croissance du phytoplancton dans le milieu acidifié mais pas de changement notable dans la structure de la communauté. Les ajouts de poussières et de cendres, de même que les variations de pH, n’ont pas eu d’effet significatif sur la production de DMS et de son précurseur le diméthylsulfoniopropionate (DMSP), probablement en raison de la courte durée (4 jours) des expériences. L’ensemble des résultats de cette thèse montre que le fer contenu dans diverses sources atmosphériques naturelles est biodisponible pour le phytoplancton du Pacifique Nord-Est et que des taux de déposition réalistes peuvent stimuler la croissance de manière notable dans les premiers jours suivant une tempête désertique ou une éruption volcanique. Finalement, les résultats de mes expériences à stresseurs multiples Fer/acidification suggèrent une certaine résistance des communautés phytoplanctoniques à la diminution du pH prédite d’ici la fin du siècle pour les eaux de surface des océans.

Evaluation of fly ash in water reduced paving mixtures, 1984

Fly ash was used to replace 15% of the cement in C3WR and C6WR concrete paving mixes containing ASTM C494 Type A water reducin9 admixtures. Two Class C ashes and one Class F ash from Iowa approved sources were examined in each mix. When Class C ashes were used they were substituted on the basis of 1 pound of ash added for each pound of cement deleted. When Class F was used it was substituted on the basis of 1.25 pounds of ash added for each pound of cement deleted. Compressive strengths of the water reduced mixes, with and without fly ash, were determined at 7, 28, and 56 days of age. In every case except one the mixes containing the fly ash exhibited higher strengths than the same concrete mix without the fly ash. An excellent correlation existed between the C3WR and C6WR mixes both with and without fly ash substitutions. The freeze-thaw durability of the concrete studied was not affected by presence or absence of fly ash. The data gathered suggests that the present Class C water reduced concrete paving mixes can be modified to allow the substitution of 15% of the cement with an approved fly ash.

Avaliação de alguns parâmetros da qualidade da anchoita (Engraulis anchoita) enlatada em óleo de girassol e em molho de tomate

O consumo de pescado no Brasil cresceu 40% nos últimos 7 anos passando de 6,46 para 9,03 kg/habitante/ano, valor que se aproxima do recomendado pela Organização Mundial de Saúde. A razão está relacionada com a subutilização de determinadas espécies e a falta de diversificação da indústria processadora para a produção de alimentos com maior valor agregado. Considerando o esgotamento de determinadas espécies com a utilização da sobrepesca, é possível o emprego da anchoita na forma de conservas através da utilização de meios de cobertura como molho de tomate e óleo comestível. Este trabalho teve como objetivo elaborar conservas de anchoita (Engraulis anchoita) com a utilização de 2 meios de cobertura: molho de tomate e óleo de girassol, submetidas a tempos de salmouragem diferenciados, 2 e 5 min e com o emprego ou não de pré-cozimento. De acordo com os padrões estabelecidos, as amostras de pescado fresco utilizadas para a execução dos enlatados apresentaram resultados físico químicos adequados comprovando o frescor do pescado envolvido no processo, ou sejam: 16,29 mg/100 g amostra para N-BVT, 7,90 mg/100 g amostra para N-TMA e pH 6,5. As conservas em molho de tomate submetidas a operação de salmouragem durante 2 min, com e sem pré-cozimento apresentaram, respectivamente, 16,57 e 16,24% proteínas, 3,94 e 4,66% lipídios, 73,0 e 73,28% umidade, 3,22 e 3,67% cinzas, 0,17 e 0,19% de cloretos (NaCl). As conservas com molho de tomate, utilizando anchoita eviscerada salmourada por 5 min, com e sem pré-cozimento, apresentaram respectivamente, 15,94 e 15,31% proteínas, 3,15 e 4,90 lipídios%, 73,70 e 73,98% umidade, 3,80 e 4,10% cinzas, 0,21 e 0,24% cloretos (NaCl). Para as conservas de anchoita em óleo de girassol, utilizando tempo de salmouragem de 2 min, com e sem pré-cozimento, apresentaram 16,97 e 16,76% proteínas, 7,68 e 5,70% lipídios, 65,87 e 68,74% umidade, 3,16 e 3,28% cinzas, 0,10 e 0,12% cloretos (NaCl), respectivamente. As conservas utilizando o pescado previamente submetido a salmouragem por 5 min e posteriormente enlatado com a adição de óleo de girassol, com e sem pré-cozimento apresentaram respectivamente, 15,97 e 15,89% proteínas, 7,91 e 5,19% lipídios, 66,26 e 68,23% umidade, 3,78 e 3,87% cinzas, 0,13 e 0,21% NaCl. As análises microbiológicas das conservas submetidas aos diferentes tratamentos mostraram ausência de Salmonella spp, Staphylococcus coagulase positiva e Clostridium sulfito-redutor, resultados estes, de acordo com o estabelecido pela legislação higiênico-sanitária brasileira. Nos testes de esterilidade comercial não foram constatadas alterações visíveis nos enlatados submetidos a incubação por 5 dias a 36 ± 1°C (determinação de micro-organismos aeróbios viáveis) e a 7-10 dias a 55 ± 1°C (termófilos). Considerando as quantidades de pescado enlatado (80, 90 e 100g), o rendimento para todas as amostras apresentaram, no mínimo, 50% de pescado em relação ao peso líquido. A avaliação sensorial realizada por teste de ordenação para a avaliação da preferência não apresentou diferenças significativas entre as amostras.

Características de cinzas e sua aplicação no tratamento de gases durante a gasificação de biomassa

Na procura de melhores combustíveis para a produção de energia térmica e energia elétrica, a biomassa apresenta-se como uma das fontes de energia renováveis menos prejudiciais ao meio ambiente, esta é considerada como um recurso neutro do ponto de vista de emissões de dióxido de carbono. Atualmente, a tecnologia predominante no domínio da conversão energética de biomassa por via termoquímica é a combustão. Contudo, verifica-se a procura de combustíveis de melhor qualidade produzidos a partir de biomassa, como por exemplo na forma gasosa (gás de combustível). A produção deste tipo de combustíveis gasosos envolvendo processos de gasificação carece do desenvolvimento de tecnologia que permita obter um gás combustível com características adequadas às utilizações pretendidas. Os problemas mais relevantes relacionados com a conversão termoquímica da biomassa incluem a produção de cinzas e de alcatrões, estes podem levar a vários problemas operatórios. O presente trabalho teve dois objetivos, a caracterização das cinzas resultantes do processo de combustão de biomassa e o estudo do efeito da aplicação das cinzas para melhorar as propriedades do gás produzido durante o processo de gasificação de biomassa, principalmente na redução de compostos condensáveis (alcatrões). As cinzas volantes da combustão de biomassa analisadas apresentam na sua constituição elementos químicos característicos da biomassa, onde o cálcio apresenta-se em concentrações mais elevadas. Em menores concentrações encontram-se sódio, magnésio, fósforo, enxofre, cloro, potássio, manganês e ferro. As cinzas de fundo, pelo contributo que a areia do leito tem, são caracterizadas por conterem grandes concentrações de silício. Durante os processos de gasificação de biomassa a concentração de compostos condensáveis diminuiu com o aumento da razão de equivalência. As cinzas, colocadas no reator de leito fixo, apresentam um efeito positivo sobre a qualidade do gás, nomeadamente um aumento de 47,8% no teor de H2 e de 11% de CO, consequentemente obteve-se um gás combustível com PCI (poder calorífico inferior) mais elevado.

How Long the Night : A Novel ; followed by an essay ‘The Ghosts of Muranów: Confronting Poland’s Jewish Past’

My novel, 'How Long the Night,' and my essay, ‘The Ghosts of Muranów: Confronting Poland’s Jewish Past,’ focus on the relationship between urban space, memory and identity. Before the Second World War Muranów was one of the largest Jewish districts in Europe. In August 1939 Poland’s capital was home to 380,000 Jews, which accounted for about 30 percent of the city’s total population. During the war the district was the central part of the Warsaw Ghetto located near the Umschlagplatz, the place from which Jews were transported to concentration camps. After the failed uprising in 1943 the Nazis burnt the entire quarter to the ground. There was nothing left, except for heaps of rubble. The debris was to be the foundation on which the new socialist realist residential district would stand. The new Muranów, erected on the ashes of the former ghetto, is a space of absence, emptiness and repressed guilt. There are no physical traces of the Jewish presence in the area, except for commemorative plaques, monuments or obelisks. Former tenement houses, shops, synagogues are gone; street names and their layout are different as well. Nevertheless, the former Jewish district is present in images, dreams (or nightmares), in fantasies, memories and stories. My novel and my essay explore the connection between place, history, memory and trauma. The space of Muranów becomes a symbolic trigger for investigation and re-examination of the forgotten or suppressed past. What is more, the novel examines the way a foreign language serves as a tool through which painful and repressed stories can be (re)told.

Monitorização das condições de operação de uma caldeira a biomassa

A reduzida informação e o pouco trabalho científico desenvolvido na área de sistemas de combustão de biomassa de média potência, faz dos objectivos propostos neste trabalho elementos importantes. O trabalho científico a seguir apresentado, vai permitir obter as bases para o desenvolvimento de condições apropriadas de operação de sistemas de combustão a biomassa, aumentando a eficiência e a rentabilidade económica deste tipo de sistema energético. O principal objetivo do presente trabalho consistiu na aplicação de metodologias de monitorização que permitam caracterizar e melhorar a eficiência do sistema de combustão, na implementação dos métodos escolhidos e na monitorização das condições de operação de uma caldeira industrial de combustão de biomassa, destacando-se: (i) monitorização dos caudais de alimentação de biomassa à caldeira realizada por sistemas de alimentação sem-fim; (ii) análise e monitorização de temperaturas e pressão; (iii) monitorização do caudal de ar de combustão; (iv) monitorização do caudal de gases de exaustão; (v) monitorização da potência térmica; (vi) monitorização da composição do efluente gasoso. A caracterização físicas de amostras de biomassa, o teste a diferentes tipos de biomassa com diferentes condições de operação e a recolha de amostras de cinzas de combustão para a caracterização físico-química são outros métodos de monitorização e caracterização aplicados. Também foi desenvolvido e aplicado um ensaio de controlo do sistema de alimentação em modo de operação manual e comparado com o sistema de controlo do sistema de alimentação em modo de operação automático. O estudo realizado permite concluir que deve ser desenvolvido e implementado um algoritmo de controlo e operação da fornalha que permita um doseamento mais adequado dos caudais de combustível e ar de combustão com vista a melhorar o desempenho do sistema combustão.

Use of Sludge as Ceramic Materials

Nowadays, with increase amounts of sludge derived from the treatment of domestic sewage put pressure into research on systems for the adequate use of these materials. The aim of the present work is to study the use of sludge ash, from sintering and calcinated process, as a raw material for the ceramic industry. Using the sewage sludge ashes as ceramic raw material there will be no contamination of soil and underground water. Metals and toxic compounds like Al, Fe, Ba, Cr, Cu, Mn and Zn oxides were analyzed and characterized by X-ray fluorescence (XRF), scanning electron microscopy (SEM) and plasma emission spectroscopy (ICP-OES). The leached material was chemically analyzed where the integration of oxides into the ceramic matrix of sludge ash was observed. Residual decomposition was analyzed by TG, DTG and DTA curves.