La contamination métallique dans l'environnement est l'un des problèmes mondiaux persistants car non seulement elle perturbe la qualité de l'environnement, mais aussi l'environnement et la santé humaine. La principale contribution à ce problème se pose principalement des activités anthropiques telles que les industries. La rareté de métal est devenu plus sévère récents où certains éléments ont été prédit pour être pleinement éradiquée depuis plusieurs décennies de la croûte terrestre. Récemment, des chercheurs ont concentré leur attention pour récupérer ces métaux dans le flux des déchets et de la réutiliser dans les processus de production industrielle. L'utilisation des déchets agricoles comme adsorbant potentiel à faible coût pour l'enlèvement des métaux lourds des eaux usées est une des technologies les plus polyvalents. Dans cette étude entre les différents adsorbants testés, coquille d'arachide établi rendements d'épuration élevés avec moins d'exigences pour un traitement ultérieur de poste pour le Cu, Pb et Zn retrait. En outre, les expériences de lots sur les principaux effets des paramètres du procédé (pH, adsorbant dosage, temps de contact et de la concentration initiale de métal) ont montré un effet majeur sur l'absorption des métaux et de l'efficacité de l'enlèvement. Pour la régénération matériau, HCl 0.2 M était la solution de désorption la plus efficace qui ne altère pas l'efficacité, jusqu'à trois cycles d'adsorption et de désorption. L'utilisation de bactéries réductrices de sulfate (SRB) dans des bioréacteurs est une autre technologie qui peut être appliqué pour le traitement de métal contaminé les eaux usées. Le SRB réduire le sulfate en sulfure, qui réagit en outre avec des métaux pour former des précipités de sulfures métalliques. Le lit fluidisé (IFB) bioréacteur inverse est la configuration qui présente la proéminence en utilisant la technologie de SRB pour le traitement des eaux usées métalliques contaminés. Deux bioréacteurs IFB ont été opérés à différents pH (7.0 et 5.0). L'activité de SRB à pH 7.0 était plus élevée qu'à un pH de 5.0, ce qui montre que le pH est le principal facteur qui affecte SRB. Cependant, le thiosulfate a montré une efficacité supérieure à celle du sulfate en tant qu'accepteur d'électrons alternatif. Le sulfure produit en utilisant du thiosulfate comme accepteur d'électrons était 157.0 mg / L, tandis que seulement 150.2 mg / L a été produit en utilisant du sulfate et il a fallu une période d'adaptation à un pH de 5.0 avant la réussite de l'opération. En outre, l'IFB a montré sa grande efficacité pour le Cu, Ni et Zn élimination des eaux usées synthétique. L'élimination de Cu et Zn étaient plus de 90% à pH 7.0 et 5.0, à une concentration initiale de métal de 25 mg / L. D'autre part, l'élimination de Ni ne était pas éliminé à une concentration initiale de 25 mg / L comme il a montré des effets toxiques à l'égard SRB. Il existe différents types de flux de déchets contaminés par des métaux qui se présentent comme un bon candidat pour la récupération des métaux comprennent e-déchets. Cet e-déchets a un fort potentiel en tant que source secondaire de métal pour récupérer les métaux en particulier base tels que Cu, Ni et Zn. Cartes de circuits imprimés (PCB) d'ordinateurs personnels ont été évalués comme source secondaire potentielle de Cu, Ni et Zn en utilisant des méthodes de précipitation hydrométallurgiques et de sulfure. Les conditions optimales pour la lixiviation des métaux étaient de 0.1 M HNO3 avec un rapport liquide solide de 20 à l'aide de PCB de 0.5 - taille des particules de 1.0 mm à 60 ° C qui a abouti à 400 mg Cu / g PCB. Avec la précipitation de sulfure à un rapport stoechiométrique de 1: 1 (Cu: S2-), la récupération de Cu a été très efficace jusqu'à 90% de la solution de lixiviation a représenté à environ 0.41 g Cu / g BPC, tout en Ni et Zn étaient récupération 40 % et 50% pour les lixiviats d'une colonne à courant ascendant de lixiviation, respectivement / Metal contamination in the environment is one of the persisting global issues since it not only disturbs the environmental quality but also the environment and human health. The major contribution to this problem arises mainly from anthropogenic activities such as industries. Metal scarcity has become more severe lately where some elements have been predicted to be fully eradicated in several decades from the earth crust. Recently, researchers have focused their attention to recover these metals from the waste stream and reuse it in industrial production processes. The use of agricultural wastes as a potential low cost adsorbent for heavy metal removal from wastewater is one of the most versatile technologies. In this study among the different adsorbents tested, groundnut shell established high removal efficiencies with fewer requirements for further post treatment for Cu, Pb and Zn removal. Furthermore, the batch experiments on the main effects of process parameters (pH, adsorbent dosage, contact time and initial metal concentration) showed a major effect on metal uptake and removal efficiency. For material regeneration, 0.2 M HCl was the most effective desorbing solution that did not alter the efficiency, up to three cycles of adsorption and desorption. The use of sulfate reducing bacteria (SRB) in bioreactors is another technology that can be applied for the treatment of metal contaminated wastewater. The SRB reduce sulfate into sulfide which further reacts with metals to form metal sulfide precipitates. The inverse fluidized bed (IFB) bioreactor is the configuration which shows prominence in utilizing SRB technology for metal contaminated wastewater treatment. Two IFB bioreactors were operated at different pH (7.0 and 5.0). The sulfate reducing activity (SRA) at pH 7.0 was higher than at pH 5.0, which shows that pH is the main factor that affects SRA. However, thiosulfate showed a higher efficiency than sulfate as an alternate electron acceptor. The sulfide produced using thiosulfate as the electron acceptor was 157.0 mg/L, while only 150.2 mg/L was produced using sulfate and it required an adaptation period at pH 5.0 prior to successful operation. Moreover, the IFB had shown its high efficiency for Cu, Ni and Zn removal from synthetic wastewater. The removal of Cu and Zn were more than 90% at pH 7.0 and 5.0, at an initial metal concentration of 25 mg/L. On the other hand, Ni removal was not removed at an initial concentration of 25 mg/L as it showed toxic effects toward SRB. There are various types of metal contaminated waste streams which pose as a good candidate for metal recovery include electronics waste (e-waste). This e-waste has a high potential as secondary source of metal to recover especially base metals such as Cu, Ni and Zn. Printed circuit boards (PCBs) of personal computers were evaluated as the potential secondary source of Cu, Ni and Zn using hydrometallurgical and sulfide precipitation methods. The optimal conditions for metal leaching were 0.1 M HNO3 with a liquid to solid ratio of 20 using PCBs of 0.5 - 1.0 mm particle size at 60 °C which resulted in 400 mg Cu/g PCBs. With sulfide precipitation at a stochiometric ratio of 1:1 (Cu:S2-), the recovery of Cu was very effective up to 90% from the leachate which accounted to approximately 0.41 g Cu/g PCBs, while Ni and Zn recovery were 40% (0.005 g Ni/g PCBs) and 50% (0.006 g Zn/g PCBs) for leachate from an upflow leaching column, respectively. This indicates Cu can be recovered from PCBs using sulfide precipitation

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Hoodia gordonii passou a ser consumida hà sÃculos, com o intuito de promover uma reduÃÃo do apetite e da ingestÃo de Ãgua e comida, e atà os dias atuais à utilizada para este fim, em diversos paÃses. O presente estudo buscou investigar possÃveis alteraÃÃes comportamentais e metabÃlicas em roedores tratados com Hoodia gordonii, em diferentes perÃodos de tratamento. Para avaliar o peso corporal do animal, ratos foram pesados diariamente, no perÃodo do tratamento e mensurado o peso, a ingestÃo de Ãgua e comida. Para investigar as alteraÃÃes comportamentais (ansiedade e depressÃo) e neuroquÃmicas, os camundongos foram submetidos aos tratamentos de 1, 8 e 15 dias com Hoodia gordonii por via oral (25 e 50mg/kg), e em seguida realizados os testes comportamentais de Labirinto em Cruz Elevado (LCE), Campo Aberto (CA) e outros grupos de camundongos foram submetidos ao teste do Nado ForÃado (NF). Com intuito de investigar o envolvimento com o sistema monoaminÃrgico, no efeito de H. gordonii sobre a depressÃo, os camundongos foram prÃ-tratados com antagonistas especÃficos para receptores de dopamina D1 e D2, de noradrenalina α1 e α2, de serotonina 5HT1A, 5HT2A/2C, 5HT3A no teste do nado forÃado. AlÃm disso, outros grupos de camundongos foram prÃ-tratados com Hoodia gordonii por 1,8 e 15 dias e uma hora apÃs tiveram o corpo estriado removido para anÃlise da concentraÃÃo de monoaminas, atravÃs da tÃcnica de HPLC e o hipocampo para realizaÃÃo de experimentos de estresse oxidativo, por quantificaÃÃo dos nÃveis de glutationa reduzida, atividade da enzima catalase, nÃveis de nitrito/nitrato e malonildialdeÃdo. Foi realizado tambÃm teste de citotoxicidade pelo mÃtodo colorimÃtrico do MTT e estudo de genotoxicidade (DNA) em linfÃcitos humanos. Os resultados revelaram que o extrato reduziu o peso corporal dos animais, bem como a ingestÃo de Ãgua e comida. Nos testes comportamentais, observou-se um possÃvel efeito ansiogÃnico no LCE. No teste do campo aberto ocorreu uma reduÃÃo da atividade locomotora no 15 dia de tratamento e no teste do nado forÃado um efeito antidepressivo-sÃmile nos trÃs tempos de tratamento, observado pela reduÃÃo do tempo de imobilidade. Este efeito antidepressivo foi revertido com o prÃ-tratamento de antagonistas noradrenÃrgicos, serotonÃrgicos e dopaminÃrgicos utilizados no estudo. O extrato promoveu um aumento na concentraÃÃo de noradrenalina e serotonina em corpo estriado de camundongos apÃs 1 dia, e aumento de dopamina, noradrenalina e serotonina apÃs 15 dias. Na avaliaÃÃo do estresse oxidativo, nÃo se observou alteraÃÃes nos nÃveis de malonildialdeÃdo (MDA), na concentraÃÃo da enzima catalase, e da glutationa reduzida, e foi possÃvel verificar uma reduÃÃo na concentraÃÃo de nitrito em ambas as doses utilizadas, em hipocampo de camundongos nos trÃs tempos de tratamento. NÃo causou alteraÃÃes histopatolÃgicas hepÃticas e renais em camundongos, apÃs administraÃÃo aguda nas doses de 550 e 2000 mg/kg. Nas concentraÃÃes de 50 a 200Âg/mL nÃo desenvolveu citotoxicidade e no teste de genotoxicidade nÃo foi capaz de alterar o DNA celular de linfÃcitos humanos. Pode-se concluir que Hoodia gordonii mostrou resultados satisfatÃrios em roedores. Entretanto, à necessÃria a realizaÃÃo de outros estudos para garantir a seguranÃa no uso do extrato e futuramente possa trazer benefÃcios à populaÃÃo. / Hoodia gordonii has become consumed centuries, in order to promote a reduction in appetite, due to reduced food and water intake. Even today it is consumed in many countries. The present study investigated possible behavioral and metabolic alterations in rodents treated with Hoodia gordonii in different treatment periods. To evaluate body weight, the rats was weighted daily during the period of treatment and measured water and food intake. To investigate the behavioral (anxiety and depression) and neurochemical changes, the mice were tested for 1,8 and 15 days of treatment with Hoodia gordonii (25 and 50mg/kg, oral), the experimental models being performed in the Elevated Plus Maze (EPM), Open Field (OP) test and other group mice submitted the Forced Swimming (FN) test. In order, to investigate the involvement with the monoaminergic system, the mice were pretreated with specific dopamine D1 and D2; α1 and α2 of noradrenaline, serotonin 5HT1A, 5HT2A/2C, 5HT3A receptor antagonists in the forced swimming test. In addition, other groups of animals were pretreated with H. gordonii for 1,8 and 15 days and after one hour, the striatum were removed for HPLC analysis of monoamines and hippocampus for the experiments of oxidative stress, such as enzymatic activity quantification of low levels of glutathione, catalase enzime, nitrite/nitrate and malondialdehyde levels. The citotoxicity (MTT) and genotoxicity (DNA) test was conducted in human lymphocytes. The results showed that, the extract reduced the body weight of the animals, as well as, food and water intake. In the behavioral testing, Hoodia gordonii presented anxiogenic effect in the EPM, reduced locomotor activity on day 1, 8 and 15 of treatment and antidepressant-like effect after the first dose administration, with reduced immobility time. It was interacted with noradrenergic, dopaminergic and serotonergic receptors used in this study. The extract promoted an increase in levels of norepinephrine and serotonin in the striatum of mice after 1 day, and increased monoamines dopamine, noradrenaline and serotonin after 15 days. The oxidative stress was not able to alter the levels of malondialdehyde (MDA), catalase, reduced glutathione in the hippocampus of mice, reduced the concentration of nitrite in both doses used in the three treatment times. The cellular DNA of human lymphocytes was not changed. H. gordonii did not cause liver and kidney after administration of doses 550 and 2000 mg/kg histopathology changes. Concentrations of 50 at 200Âg/mL did not develop citotoxicity and genotoxicity test, was not able to change the cellular DNA of human lymphocytes. It can be concluded that, Hoodia gordonii showed great results in rodents. However, other studies itÂs necessary to ensure the safe use of the extract, and it can be approved or not in our country.

No description available.

This dissertation is an investigation and analysis of the contributions of the human organism to climate change, specifically concerned with its adverse effect on the biosphere. The focus of the analysis rests on three phenomena distinctive to humans participating in globalized economies and modernized societies; the distortions of anthrosupremacy, an uncritical development of technology, and an unhealthy cathexis with economic growth. These are analyzed and identified as stark contributors to the creation, proliferation, and pervasiveness of systems contributing to the decline of the biosphere. These phenomena serve to dissociate humans from the consequences of their actions in systemic ways; thereby thriving by preying on the faults of human agency. Using a biogenic framework to analyze human agency, these faults are identified as problematic to the teleological pursuits of the human organism (i.e., extantcy). An analysis of these phenomena in relationship to the faults in human agency is done to create an awareness of how certain mythologies, technologies, and socioeconomic practices have created enabling constraints that deter a more efficacious and sustainable exercise of human agency. Existing strategies and philosophies that have been promoted to address the issue have failed to account for these enabling constraints and, have therefore, fallen short of creating their desired effect in practical ways. This dissertation concludes that, without altering these enabling constraints to allow for a more efficacious and sustainable exercise of agency, the human species is less likely to persist into the indefinite future.

This work addresses biogenic formaldehyde (CH₂O) generated by wood during the manufacture of non-structural wood-based composites, from which CH₂O emissions are regulated. The target for regulation has been anthropogenic CH₂O released from hydrolytically unstable amino resins like urea-formaldehyde. However, current regulations (the Formaldehyde Standards for Composite Wood Products Act, signed into law in 2010 and implemented in 2016) restrict allowable emissions to such low levels that biogenic CH₂O may affect regulation compliance. The industry has met the latest regulations with new amino resin technologies. Nevertheless persistent anecdotal reports suggest that biogenic CH₂O complicates regulation compliance. This work represents an industry/university cooperation to seek a more thorough understanding of biogenic CH₂O, to begin documentation of biogenic CH₂O levels in wood, and to study the conditions and chemical mechanisms of its formation. Efforts began by establishing CH₂O analysis using the fluorimetric acetylacetone determination. A custom 12-liter chamber with controlled temperature and relative humidity, and "ultrapure" nitrogen (N₂) ventilation was created to measure CH₂O emissions from flakes sampled from four Virginia pine (Pinus virginiana) trees. Emissions from never-heated specimens varied significantly among the four trees, ranging from 0.02 – 0.19 µg CH₂O/m³g dry wood. Heating (200°C, 1 hour), followed by chamber equilibration, resulted in significantly increased emissions on the order of 50%. Sequential heating, followed by chamber equilibration (in other words, heat/equilibrate/measure emission/repeat), resulted in declining emissions suggesting that a finite chemical source of CH₂O was being depleted by the sequential heat treatment. Flake specimens were stored in the open laboratory, and over 2-3 months laboratory storage, initially high emitting specimens gradually emitted less CH₂O, and initially low emitters gradually emitted more CH₂O. Concerns over laboratory contamination were perhaps allayed when background levels of laboratory CH₂O were determined to be similar to the background levels in the ultrapure N₂ used to ventilate the chamber. Measurement of emissions was abandoned, and thereafter a simple water extraction technique (~ 94% CH₂O recovery) was used to measure the CH₂O content of never-heated and heated wood specimens, where the difference was identified as CH₂O generated due to heating. Increment cores from living Virginia pine (Pinus virginiana), yellow-poplar (Liriodendron tulipifera), and radiata pine (Pinus radiata) trees were used to measure CH₂O content and CH₂O generation due to heating (200°C, 10 min). Significant variations within and between trees of the same species were observed. Tissue types (juvenile/mature, heartwood/sapwood) sometimes correlated to higher CH₂O contents and greater heat-generation potential; but sometimes not depending upon species. Heating increased CH₂O levels 3-60 fold. Heating with high moisture levels caused greater CH₂O generation than for dry specimens. This moisture effect and a separate serendipitous observation suggested that CH₂O generation is acid catalyzed. Radiata pine generated extraordinarily high CH₂O levels when heated, far exceeding the other two species. It was suggested that pine extractives might catalyze CH₂O generation, perhaps in lignin. Pinus virginiana wood was heated (200°C, 10 or 60 min) while dry or after aqueous/acid or base pretreatment in order to reveal mechanisms of formaldehyde (CH₂O) generation. Among wood structural polymers, lignin was the overwhelming source of biogenic CH₂O, consistent with prior reports. The effects of wood extractives are mentioned below. The selection of acid catalyst strongly affected CH₂O generation as predicted in the acidolysis literature of lignin model compounds and isolated lignins. Lignin methoxyl cleavage was also observed, but was considered an unlikely source of thermochemical CH₂O. Alkaline pretreatments suppressed CH₂O generation. Regarding wood-based composite manufacture, the implications are that lignin reactions can be manipulated during hot-pressing. Potential benefits include reduced product emissions, and/or novel crosslinking strategies using biogenic CH₂O. Heat generation of CH₂O in Virginia pine and radiata pine was substantially reduced by extractives removal, but there was no such effect in yellow-poplar wood. Results suggested that pine extractives promote CH₂O generation by catalyzing or otherwise promoting C2 cleavage (acidolysis) in lignin. Thioacidolysis demonstrated that pine lignin reactions were strongly dependent upon the presence or absence of the extractives. When present, pine extractives seemed to promote C2 cleavage (CH₂O generation), but otherwise reduced the overall extent of lignin degradation. When pine extractives were removed, lignin suffered substantial degradation, but apparently less C2 cleavage since CH₂O generation was reduced. In contrast, thioacidolysis showed that yellow-poplar extractives appeared to promote lignin degradation, but extractives removal had no detectable impact on CH₂O generation. Implications exist for biorefinery research because it was shown that lignin reactions can be strongly affected by wood extractives. Two dimensional, proton-carbon, correlation NMR spectroscopy (2D NMR), and solvent submersion dynamic mechanical analysis (DMA) was used to investigate wood changes caused by heating in the presence or absence of external acid catalysis. 2D NMR was relatively insensitive to fine lignin changes that were detected using thioacidolysis. 2D NMR was effective for observing lignin changes under more extreme heating conditions, and evidence was found for lignin crosslinking reactions that probably occurred through substitution into lignin aromatic rings. DMA showed that most heating conditions caused an increase in the lignin glass transition temperature (Tg), consistent with heat-induced lignin crosslinking. Under one experimental condition of wood heating, DMA showed a reduction in the lignin glass transition temperature (Tg). This suggested that lignin cleavage without subsequent repolymerization might be promoted by carefully controlled conditions, and this has implications for biorefinery research where lignin repolymerization can be problematic. Finally, this work strongly supported the hypothesis that lignin generates CH₂O through well-known acidolysis pathways where CH₂O is borne from the lignin gamma-methylol group. Therefore, it was predicted that upon heating corn (Zea mays L.) stalk should generate less CH₂O than wood because corn stalk lignins exhibit a high degree of coumaric acid esterfication at the gamma-methylol group. This hypothesis was perhaps verified- it was found that in 4 out of 6 experimental heating conditions that corn stalk generated significantly less CH₂O than Virginia pine. / Ph. D.

Les nanoparticules exposent beaucoup de propriétés uniques en comparaison de la possession de matériels (matières) en gros (vrac) à leur haute surface au ratio de volume. Des nanoparticules de sélénium élémentaires exposent aussi les nouvelles propriétés qui sont exploitées dans la formation de cellules solaires, des redresseurs de semi-conducteur et le déplacement (déménagement) de mercure et le cuivre. Cependant, la synthèse chimique de nanoparticules de sélénium élémentaires est coûteuse, exige des équipements spécialisés et utilise des produits chimiques toxiques. D'autre part, la production biologique de nanoparticules de sélénium élémentaires (BioSeNPs) peut être un remplacement(remplaçant) vert pour les chimiquement produits. BioSeNPs sont produit par la réduction microbienne de sélénite et selenate. La source du sélénium oxyanions peut être le wastewaters, où la réduction microbienne est employée comme une technologie de remédiation pour le déplacement (déménagement) de sélénium (...) / Nanoparticles exhibit many unique properties as compared to the bulk materials owning to their high surface to volume ratio. Elemental selenium nanoparticles also exhibit novel properties that are exploited in formation of solar cells, semiconductor rectifiers and removal of mercury and copper. However, the chemical synthesis of elemental selenium nanoparticles is costly, requires specialized equipments and uses toxic chemicals. On the other hand, biological production of elemental selenium nanoparticles (BioSeNPs) can be a green replacement for the chemically produced ones.BioSeNPs are produced by microbial reduction of selenite and selenate. The source of the selenium oxyanions can be the wastewaters, where microbial reduction is employed as a remediation technology for the removal of selenium. The formed BioSeNPs are colloidal poly-disperse particles with negative surface charge and are present in the effluent of the microbial reactor. However, the properties of these BioSeNPs are not very well understood. This knowledge would help us to produce better quality selenium nanomaterials, exploit produced BioSeNPs in the wastewater treatment and control the fate of these BioSeNPs in the microbial reactors. The characterization of BioSeNPs revealed the presence of the extracellular polymeric substances (EPS) on the surface of BioSeNPs. The EPS was identified to control the surface charge and to some extent the shape of the BioSeNPs. It was also found that the microbial reduction at 55 and 65 °C can lead to the formation of selenium nanowires as compared to nanospheres when the reduction takes place at 30 °C. These selenium nanowires are present in trigonal crystalline structure and are colloidal suspension, unlike the chemically formed trigonal selenium nanorods. This colloidal nature is due to negative ζ-potential values owning to the presence of EPS on the surface of biogenic selenium nanowires. Since proteins are a major component present in the EPS, the presence of various proteins on the surface of BioSeNPs was determined. The interaction of the various amino acids with the BioSeNPs was also evaluated.The interaction of heavy metals and BioSeNPs was studied with a view of developing a technology where BioSeNPs present in the effluent of an upflow anaerobic sludge blanket (UASB) reactor are mixed with heavy metals containing wastewater leading to removal of both BioSeNPs and heavy metals. It was found that Cu, Cd and Zn can be effectively adsorbed onto BioSeNPs. Cu was 4.7 times preferentially adsorbed onto BioSeNPs. The interaction of BioSeNPs with the heavy metals led to less negative ζ-potential of BioSeNPs loaded with heavy metals and thus better settling of BioSeNPs was achieved. The presence of BioSeNPs in the effluent of the microbial reactor treating selenium oxyanions containing wastewaters is undesirable due to higher total selenium concentrations. Thus, the attempts to capture of these BioSeNPs in the biomass/bioreactors were made. The activated sludge reactor system was investigated to aerobically reduce selenite to BioSeNPs and trap them in the activated sludge flocs. Around 80% of the fed selenium was trapped in the biomass. Sequential extraction revealed that the trapped selenium is BioSeNPs. The trapping of BioSeNPs in the sludge improved the settleability and hydrophilicity of the activated sludge flocs. When the UASB reactor were operated under mesophilic and thermophilic conditions, the total selenium concentration in the effluent under thermophilic conditions were lower than that of observed in mesophilic conditions suggesting better trapping of BioSeNPs.Keywords: Selenium, bioreduction, BioSeNPs, EPS, ζ-potential, heavy metals, activated sludge, UASB reactors, thermophilic

The aim of this study was to evaluate the influence of an extremely low frequency sinusoidal magnetic field (ELF MF) with frequency of 10 Hz and intensity of 1.8-3.8 mT on the levels of the biogenic amines dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 3-methoxytyramine (3-MT), 5-hydroxytryptamine (5-HT), 5-hydroxyindolacetic acid (5-HIAA), and noradrenaline (NA), as well as on DA and 5-HT turnover in corpus striatum and frontal cortex of adult male Wistar rats. We found that ELF MF exposure for 14 days, 1 h daily, did not influence the level of the examined biogenic amines and metabolites, but increased the rate of synthesis (turnover) of DA and 5-HT in rat frontal cortex as compared to control, sham exposed rats. On the basis of the present results and our previous findings, extremely low frequency magnetic field (ELF MF) exposure has been found to alter both turnover and receptor reactivity of monoaminergic systems, as well as some behaviors induced by these systems or their agonists and antagonists.

Presently within the scientific literature no terrestrial biogenic silica models exist that compare by magnitude, processes transporting silica. Change in vegetation type has the potential to alter dissolved concentrations of Si in rivers and ultimately the oceans. Diatoms greatly depend on Si concentrations for growth, and as a result land cover change may have influenced onset diatom radiation during the Cenozoic. To expand our understanding of this cycle, a terrestrial biogenic silica model is proposed. This model accounts for biogenic silica production, dissolution and leaching through soils, as well as providing estimates for annual silica soil storage. A case study performed using the constructed biogenic silica model, showed an increase in oceanic DSi concentration during the Miocene (period of diatom diversification). However, this increase does not appear to have been sufficient to trigger global diatom radiation, suggesting multiple geographically isolated locations for this diversification.

We theoretically investigate the fluid mechanics of self-propelled (or swimming) bodies. An important factor concerning the hydrodynamics of locomotion concerns the relative strength of inertial to viscous forces experienced by the swimmer, the ratio of which is quantified by the Reynolds number, Re. Particular attention is given to the regime where Re is intermediate, where viscous and inertial forces are both relevant to fluid motion. We study two broad classes of swimmers: ‘pushers’ and ‘pullers’. Pushers produce thrust from the rear of their body, while pullers generate thrust from the front. We first investigate the near-field flow due to pushers and pullers by numerically solving the Navier-Stokes equations for Re of 0.01–1000. We show that, although the locomotion of pushers and pullers is similar at small Re, drastic differences due to fluid inertia arise as Re is increased. Most remarkably, flow instabilities develop at much smaller Re for a puller than a pusher. Further, we investigate the large scale fluid transport induced by a swimmer as a function of Re in the context of the induced ‘drift volume’. The drift volume quantifies the volume of fluid swept out by a ‘dyed’ fluid plane that is initially perpendicular to the body’s path. However, we first address the previously unsolved problem of the drift volume due to a body that is towed by an external force at finite Re. While the drift volume is comparable to the body volume in inviscid flow (Re ! 1), it is much larger when Re is finite due to viscous effects. The drift volume due to a swimmer is smaller than that due to a towed body because swimmers generate a weaker far-field flow. However, it is still potentially large compared to the volume of the swimmer’s body in the viscously dominated small-Re regime. However, the drift volume of a swimmer quickly diminishes as Re is increased.

Our knowledge of how oil spills affect coastal environments is severely limited by the shortage of research that addresses the impact of these events on phytoplankton, the single most important group of organisms in the marine ecosystem. This scarcity of knowledge is mainly attributed to the absence of baseline data, preventing the comparison of pre- and post-spill populations. This unique study aims to identify how dinoflagellates and diatoms, the two major groups of phytoplankton in coastal marine environments, have been affected by the 1989 Exxon Valdez oil spill in Prince William Sound (PWS), Alaska. To do this, sedimentary records of dinoflagellate cysts, produced during a dinoflagellate's life cycle and preserved in the sediment, and biogenic silica, a proxy for diatom abundance, were analyzed prior to, during and after the oil spill. The analysis of two well-dated cores in PWS reveals marked increases during the oil spill in the concentrations of total cysts of the species Operculodinium centrocarpum sensu Wall and Dale, (1966) and Dubridinium spp. Total cyst concentrations doubled in core P-10 from 362 to 749 per g, while in core P-12 the increase was from 1175 to 1771 cysts g-1. During this peak in cyst concentrations, total concentrations were 3 and 2 standard deviations greater than the mean in cores P-10 and P-12, respectively. Dubridinium spp. showed a five and sevenfold increase in concentrations in cores P-10 (4 to 20 cysts g-1) and P-12 (16 to 110 cysts g-1), respectively, while O. centrocarpum sensu Wall and Dale, (1966) doubled in concentrations in the two cores (P-10: 117 to 276 cysts g-1; P-12: 268 to 495 cysts g-1). Biogenic silica values did not show significant changes throughout the cores, with values varying between 8% and 9% in core P-10 and 9.0% to 10.9% in core P-12. These changes lie within or very close to the standard deviation of the analyzed standards, suggesting that much of the changes could be analytical noise. The dinoflagellate cyst signals seen in this study are comparable to those seen as a result of nutrient enrichment in estuarine systems, suggesting that the 1989 Exxon Valdez oil spill and its remediation had a stimulatory effect on some taxa of cyst- producing dinoflagellates. This impact appears to be short-lived, with cyst concentrations returning to pre-spill levels within two years of the event. The lack of change in diatom abundance, on the other hand, suggest that diatom abundance remained relatively constant during the entirety of the sample period. / Graduate / 2020-07-10