Orientador: Maria Del Pilar Taboada Sotomayor / Co-orientador: Ademar Wong / Banca: Gustavo Troinano Feliciano / Banca: Renata Kelly Mendes Valente / Resumo: Este trabalho descreve a preparação e viabilidade de sensores eletroquímicos à base de nanomateriais carbonáceos e catalisadores biomiméticos da enzima P450, visando à obtenção de sensores sensíveis e seletivos para determinação de tetraciclina. Para tal, inicialmente foram construídos sensores eletroquímicos usando pasta de carbono modificada com 10% (m/m) de MWCNT-COOH (nanotubos de carbono de paredes múltiplas funcionalizados com grupos carboxila) e 10% (m/m) de óxido de grafeno (GO). A Voltametria de pulso diferencial adsortiva com varredura anódica (VPDadVA) permitiu obter melhores resultados em solução tampão fosfato 0,1 mol L-1 (pH 7,0); potencial e tempo de acumulação de 0,2 V e 30 s, respectivamente. Sob estas condições o sensor apresentou uma faixa linear de resposta entre 1,2 x 10-5 e 1,7 x 10-4 mol L-1, sensibilidade de 1,2 x 104 (±1,0x103) μA mol L-1 e limite de detecção de 3,6 x 10-8 mol L-1. Este sensor foi aplicado na determinação de tetraciclina em urina sintética, águas de rio e medicamentos, obtendo-se recuperações com valores próximos a 100% e valores de repetibilidade em termos do desvio padrão relativo (DPR) abaixo de 6%. Na segunda etapa do trabalho, visando à obtenção de um sensor biomimético, além dos materiais nanopartículados, as pastas de carbono foram individualmente modificadas, com 11 compostos organometálicos que mimetizam o sitio ativo da enzima P450. Dentre eles, apenas a bispiridilftalocianinaferro (II), cloreto de 5,10,15,20-tetrafenil-21H,23H-porfirinaferro (III) e 1,2,3,4,8,9,10,11,15, 16,17,18,22,23,24,25-hexadecafluoro-29H,31H-ftalocianinacobalto (II) apresentaram resposta promissora usando voltametria cíclica. Entretanto, quando realizados experimentos de quantificação através de VPDadVA nas condições otimizadas, vi nenhum dos sensores mostrou respostas satisfatórias, apesar dos esforços realizados para conseguir a... / Abstract: This work describes the preparation and feasibility of electrochemical sensors based on carbonaceous nanomaterials and biomimetic catalysts of the P450 enzyme, in order to obtain sensitive and selective sensors for determination of tetracycline. For this, electrochemical sensors were initially constructed using carbon paste modified with 10% (w/w) of MWCNTCOOH (carbon nanotubes multi-walled functionalized with carboxyl groups) and 10% (w/w) of graphene oxide (GO). Differential pulse with adsorptive anodic stripping voltammetry (DPadSAV) provided the best results in phosphate buffer 0.1 mol L-1 (pH 7.0) and accumulation potential and time of 0,2 V and 30 s, respectively. Under these conditions the sensor showed a linear response range between 1.2 x 10-5 and 1.7 x 10-4 mol L-1, sensitivity of 1.2 x 104 (± 1,0 x 103) A mol L-1 and detection limit of 3.6 x 10-8 mol L-1. This sensor has been applied to the determination of tetracycline in synthetic urine, river water and pharmaceutical formulations with recovery values close to 100% and repeatability in terms of relative standard deviation (RSD) below 6%. In the second stage of the work in order to obtain a biomimetic sensor, in addition to the nanoparticulate materials, carbon pastes were individually modified, with 11 organometallic compounds that mimic the active site of P450 enzyme. Among them, only bis(pyridil)phthalocyanine iron (II); 5,10,15,20-tetraphenyl-21H, 23H-porphyrin iron (III) chloride and 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H,31H-phthalocyanine cobalt (II) showed promising response using cyclic voltammetry. However, when performed experiments by VPD and DPadSAV in optimized conditions, none of the sensors showed satisfactory resposes, despite the efforts made to achieve the quantification of tetracycline. viii Showing that in this case, the these compounds did not improve the sensor response previously obtained... / Mestre

Le carbone est un élément essentiel à la surface de la Terre. Il entre aussi bien dans la composition de certains minéraux (carbonates) que dans les molécules du vivant. Les roches métamorphiques contiennent également des matériaux carbonés (MC) dont l’origine peut être variée. Les MC sous forme solide (matériaux carbonés partiellement ou parfaitement graphitisés) jouent un rôle majeur dans l’évolution pétrologique et géochimique d’une roche enfouie en zone de subduction. Si notre connaissance des MC métamorphiques a largement progressée ces dernières années sur la base d’études naturalistes, expérimentales ou théoriques, il reste de nombreuses questions par exemple autour de la détermination des sources des MC dans les roches métamorphiques. Le rôle des minéralisations en tant que facteur de préservation des MC d’origine biologique (biogénique) est encore mal compris. Nous avons étudié des échantillons naturels (formation Marybank, Nouvelle Zélande) métamorphisés dans le facies schiste bleu et contenant des fossiles végétaux graphitisés et montrant une remarquable préservation morphologique. Nous dressons ainsi un inventaire des processus minéralogiques et chimiques ayant contribué à préserver, ou oblitérer, certaines informations portées par le matériau biologique originel, et plus généralement par le fossile. Pour ce faire, nous avons employé des techniques de caractérisation minéralogiques et géochimiques à haute résolution spatiale des MC fossiles et des minéraux. Nous montrons ainsi que la remarquable préservation morphologique s’accompagne d’une recristallisation avancée de la minéralogie et des MC constituant le fossile. Nous mettons aussi en évidence la présence spectaculaire de nanoparticules de TiO2 dans les MC des fossiles et nous discutons des mécanismes possibles de formation de ces minéralisations exceptionnelles.Il existe des mécanismes complexes, abiotiques, fortement liés aux interactions fluide-roche et permettant la formation de MC graphitiques dans les roches métamorphiques. Ces processus rendent complexe l’étude et l’interprétation des MC dans les roches. Toutefois, ils révèlent le rôle majeur des fluides et des assemblages minéraux dans la dynamique métamorphique du carbone. Nous avons réalisé l’étude détaillée d’un contact entre des serpentinites et des métasédiments (Malaspina, Corse Alpine) au niveau duquel les métasédiments sont décarbonatés. A cause des conditions réductrices imposées par les serpentinites sous-jacentes, le carbone inorganique ainsi libéré précipite sous forme de graphite. Nous employons des méthodes géochimiques, minéralogiques et pétrologiques complémentaires qui permettent de distinguer différentes catégories de matériaux carbonés dans ces roches, mais aussi de proposer un scénario bien contraint de formation abiotique du graphite. Cette étude permet alors de discuter du rôle des gradients redox sur la dynamique du carbone dans une roche métamorphique. L’ensemble de ces travaux sont autant d’exemples qui soulignent certains aspects encore peu explorés du rôle pétrologique fondamental des MC dans les roches métamorphiques. / Carbon is an essential element on the Earth’s surface. It is involved in the formation of certain minerals (carbonates) as well as biomolecules. Metamorphic rocks also contain carbonaceous materials (CM) with various possible origins. Solid CM (partially or completely graphitized CM) play a major role in the petrological and geochemical evolution of a subducted rock. If our knowledge of metamorphic CM increased over the last years based on naturalist, experimental or theoretical studies, many issues remain as to the source of CM in metamorphic rocks for example.The role of mineralization as a factor of preservation of CM of biological origin (biogenic) is still poorly understood. We studied natural samples (Marybank formation, New Zealand) metamorphozed in the blueschist facies and which contain carbonaceous plant fossils that display a remarkable morphological preservation at the microscopic scale. We investigate mineralogical and chemical processes that contributed to preserve, or obliterate, information carried by the original biomaterial, and, more generally, by the fossil. To do so, we have characterized the fossils and the minerals using analytical technics with high special resolution. We show that the remarkable morphological preservation is accompanied by the advanced recristallization of the mineralogy compositing the fossils. We also show the presence of spectacular TiO2 mineral nanocristals in the CM composing the fossils and we discuss about possible mechanisms leading to the formation of these exceptional mineralizations.Complex abiotic processes, intimately linked to fluid-rock interactions, allow the formation of graphitic CM in metamorphic rocks. These processes hinder the study and interpretation of CM in rocks. Nevertheless, they also reveal the major role of fluids and mineral assemblages in the metamorphic dynamics of carbon. We carried a detailed study of a contact between serpentinites and metasediments (Malaspina, Alpine Corsica) that display complete carbonate destabilization. Because of the reduced conditions imposed by the underlying serpentinite, the inorganic carbon released has precipitated and formed graphite. We use geochemical, mineralogical and petrological complementary tools that allow to distinguish different categories of CM in these rocks, and we propose a well constrained scenario for the formation for this abiotic graphite. This study allows discussing the role of redox gradients on the dynamics of carbon in a metamorphic rock.These are all examples stressing the important, and yet poorly explored, petrological role of CM in metamorphic rocks.

Macroscopic “carbonaceous” fossils such as Grypania, Katnia, Chuaria, and Tawuia play a critical role in our understanding of biological evolution in the Precambrian and their environmental implications. Unfortunately, understanding of these fossils remains limited by their relative simplicity of form, mode of preservation, and broad taphonomic variability. As a result, debate continues as to even the fundamental taxonomic affinity of the organisms. Megascopic coiled forms (i.e. Grypania and Katnia), for instance, have been interpreted as trace fossils, multicellular algae, prokaryotic filaments, macroscopic bacteria, cyanobacteria, or a transitional form from macroscopic to megascopic bacterial life. Similarly, Chuaria and Tawuia have been interpreted as compressed prokaryotic colonies, algae or algal reproductive stages, and multicellular plant material. Accessibility of new material and increasingly sophisticated means of analysis warrant a new look at these ancient fossils. Understanding the biological affinity of Grypania, in particular, is critical because current opinion is split as to whether these megascopic structures are more likely represent either multicellular bacteria or multicellular algae. Confirmation of either a bacterial or algal affinity would strongly influence fundamental understanding of biospheric evolution, particularly in terms of ocean oxygenation and the availability of bioessential trace metals. Although estimates for the degree of oxygenation required for a Grypania-like multicellular algae are only about 10 % present atmospheric levels (PAL), this estimate is still substantially higher than estimates based on geochemical data suggesting that oxygen levels may not have reached 10% PAL until the latter Neoproterozoic. It has been hypothesized that protracted oxygen of the Proterozoic biosphere may have played a critical role in the availability of redox-sensitive nutrients necessary for bacterial nitrogen fixation and the limiting of eukaryotic evolution. Within this context, our understanding of the taxonomic affinity of Grypania may profoundly affect our understanding of Earth’s biospheric evolution. This thesis provides morphological and geochemical analyses of Grypania spiralis from more than 100 newly collected specimens from the Belt Supergroup for comparison to previously collected specimens from all other known Grypania-bearing localities. Data is used to explore questions regarding the morphology, structural complexity, mode of preservation, and chemistry of fossil material, and to hypothesize on the taxonomic affinity of Grypania spiralis and its implications for biospheric evolution.

Carbonaceous engine deposits tend to accumulate on most of the inner surfaces of the car engine. The presence of these deposits leads to a deteriorated efficiency of the engine and a number of adverse effects, such as higher propensity of the engine to knock. It has been proposed that selective adsorption of some of the fuel components in the porous deposits (and changing composition of the pre-combustion fuel) could be a contributing mechanism of the diminished efficiency of the engine. This, as well as other mechanisms of the deposits action, crucially depend on the porous structure of the material. Therefore, the aim of this investigation is to develop a method, which is able to accurately characterize the internal porous structure of the engine deposits and predict their adsorption properties at different conditions. This should allow us to assess whether the selective adsorption of fuel components is indeed a plausible contributing mechanism to the diminished performance of the engine. Accurate characterization of the engine deposits faces several difficulties due to their complex porous structure and chemical composition. A widely adopted approach in the characterization of activated carbons, which combines molecular simulation, specifically grand canonical Monte Carlo (GCMC) in slit pores, and experimental adsorption isotherms, is the starting point for the method suggested in this work. In this thesis, we will demonstrate that, by systematic modification of the solid-fluid interaction in the molecular simulation, we are able to correctly account for the chemical structural heterogeneity of the samples used. The new parameters of solid-fluid interaction allow us to extract representative pore size distributions and investigate the adsorption properties under different conditions of temperature and pressure, based on the obtained pore size distribution. Specifically, using the experimental data from a single ethane isotherm at 278K we accurately predict ethane adsorption at other temperatures and in different samples. Additionally, the proposed method is able to predict the adsorption of more complex hydrocarbons, i.e. n-butane and isobutane. The performance of the method is assessed by comparing the simulations results with the experimental adsorption measurements data on the engine deposits samples. Another important capability of the method is that it enables us to generate adsorption predictions of two key components commonly used to represent the combustion properties of the fuel, n-heptane and isooctane. We explore the equilibrium adsorption properties of these components based on the determined pore size distributions of the deposit samples. The results presented in the thesis highlight the importance of the adsorption in the internal porous structure of the engine deposits. The present study reinforces the value of molecular simulation combined with a limited number of experimental measurements, to accurately characterize heterogeneous carbonaceous materials and to make predictions at different conditions with sufficient precision.

Various organic compounds, including graphitic carbon, can be formed abiotically in hydrothermal systems, such that evidence for early life must necessarily combine geological, morphological and geochemical data to be compelling. Carbonaceous materials (CM) have been isolated from three rock packages of mid to early Archaean age from the Pilbara Craton of Western Australia. This CM has been subjected to a multidisciplinary approach utilising a variety of analytical and observational techniques, in an attempt to establish the occurrence, associations, mineral affinities, historical environments of growth, and the metamorphic/thermal history experienced by what may be some of the earliest, relatively pristine record of 3500 million year old life on this planet. CM isolated from drillcore obtained from the first of these localities, the 3.24 Ga Sulphur Springs volcanic hosted massive sulphide (VHMS) deposit, occurs as isotopically light (δ13C values of −34.0 ‰ to −26.8 δ13C) finely striated, lenticular to banded material emplaced parallel to original sedimentary bedding planes within the fine-grained silicified epiclastic hanging wall sediments. Petrological and transmission electron microscopy (TEM) observations have revealed well-preserved bundles of filamentous and tubular structured microbial remains closely resembling both modern-day and more ancient microbial forms documented from sea floor hydrothermal environments. Total organic carbon (TOC) has a range of <1.0 to 2.3 %, while the thermal maturity (%Ro) of the filamentous bundles points to maximum temperatures since deposition of around 90–100 °C, a factor that has enabled the preservation of their morphology. These results are suggestive of a well-developed Archaean sediment-hosted microbial community, situated within a basinal environment associated with an active centre of seafloor hydrothermal activity. The majority of the CM isolated from drillcore samples of the second locality, the 3.46 Ga Salgash Subgroup, a lower member of the Apex Basalt, also appears as in situ, bedding parallel bands intercalated with foliated altered argillaceous sandstone beds. TOC of the samples ranges from 1.25 to 11.48 %, while carbon content varies from 2.05 to 32.17 %. δ13C results are relatively heavy, varying from -30.4 to -22.5 ‰. Thermal maturity indicators of 10-13 %Ro suggest the CM having been subjected to temperatures greater than normally obtained from processes associated with burial. Electron paramagnetic resonance (EPR) results showed this CM in a highly ordered graphitic state. Optically, the graphite lacks the typical pronounced anisotropy characterising graphites in metamorphic terranes. Graphitisation therefore, is likely the result of rapid heating at very high temperature. HRTEM of this material revealed an extremely high level of molecular ordering contemporaneous with the presence of the C60 fullerene molecules within carbon nanotubes. These forms are a key to the distinction between biologically and abiotically synthesized CM, both by their small size and their resistance to thermal degradation. The occurrence of these carbon forms in terrestrial deposits is rare, and usually associated with wildfires, lighting strike or meteoritic impact. In the case of the Salgash CM, the formation of these molecules and the isotropic graphitised state of the CM is interpreted as a result of emplacement under pressure of very high temperature (komatiitic/ peridotite) lavas. The thermal overprint of the CM by such a high temperature process resulted in the volatilisation of the organic material, destruction of any primary biological morphology and the subsequent reorganisation of the residual CM, resulting in increased molecular ordering. In the third part of the study, CM isolated from drillcore samples of the ca. 3.5 Ga Dresser Formation bedded black chert-barite units, occurs in both dispersed and layered forms, interlayered with fine-grained silica. The intimate association of the CM and silica strongly resembles silicified microbial colonies from active hydrothermal systems, which have been previously proposed as analogues of Archaean hydrothermal sites. Isotopically light δ13C values from -38.2 to -32.1 ‰, and the association of C, H, and N, are highly indicative of a biological origin for the material. Palaeotemperatures calculated from δ18O isotope analysis of quartz chips indicate a depositional temperature for the hydrothermal veins ranging from ~120 °C to ~200 °C. 207Pb-206Pb isotope analyses conducted on pyrites extracted from the interbedded barite units reveal a dual MORB and Erosion mix source for the Pb, which gives an average 207Pb/206Pb age of 3531±42 Ma for the deposit. Ro measurements reveal four distinct CM populations, defined as ACM, A1CM, BCM, and CCM, which represent temperatures ranging from 170 °C to potentially >400 °C. TEM and HRTEM observations of the lower temperature CM population show morphological entities strongly suggestive of microbial remains, including possible cell wall remnants. Higher Ro rank CM commonly fills or coats mineral grains and lacks distinguishable structures, which is consistent with an increased thermal degradation /hydrothermal overprint. The geological setting and mineralogy of the Dresser Formation endorse its formational history as a silica-barite dominated seafloor hydrothermal deposit, most likely analogous to modern “white smokers”. The occurrence of the predominant CM (type ACM) in more or less continuous bands and laminae within the sedimentary rocks suggest an in situ, syndepositional source for the majority of this material, whereas the dispersed nature of type BCM particles indicates a recycled nature. The occurrence of type CCM within fluid inclusions gives an insight into the primary morphology of the non-degraded original microbial cells that may have existed at that time. These observations, combined with the carbon isotopic heterogeneity and fractionations are suggestive of chemosynthetic microbes occupying a seafloor hydrothermal system where rapid silicification at relatively low temperature preserved the CM. Finally, in an effort to further understand the CM structures observed in the rocks of the Dresser Formation in the context of present day microbial colonies in similar environments, a comparative morphological study was conducted using a potential modern analogue derived from an active seafloor hydrothermal environment. Such methodology utilises the standard classification used in biological species identification, which is initially based on visual identification of specific features, whether by the naked eye, light microscopy or electron microscopy. The extant hyperthermophilic microbe Methanocaldococcus jannaschii was cultured under conditions similar to the Archaean seafloor, simulating an increased thermal maturity by artificially induced autoclaving at 100 °C (1 atm) and 132 °C (2 atm). A striking resemblance to the early Archaean forms observed in the Dresser CM was evident in both wall structure and thermal degradation mode of the cultured microbe. Cell disintegration of the cultures occurred at 100 °C marking the limits of life, whereas complete disintegration, deformation and shrinkage of the cells occurred at 132 °C. These comparative observations present as a feasible way of understanding the structural features in CM identified in Archaean sedimentary packages.

Μέχρι σήμερα η επίδραση της αλατότητας στη διεργασία της ρόφησης των οργανικών ρύπων σε στερεούς ροφητές έχει μελετηθεί θεωρώντας ότι η ρόφηση είναι μία γραμμική διεργασία που εξαρτάται από το κλάσμα του οργανικού άνθρακα. Μελέτες της τελευταίας δεκαετίας έχουν αποδείξει ότι η ρόφηση των οργανικών στο περιβάλλον δεν είναι απαραίτητα μία γραμμική διεργασία. Για ιζήματα και εδάφη με σωματιδιακούς ανθρακούχους ρύπους, όπως είναι τα σωματίδια της αιθάλης ή των εξανθρακωμάτων, έχουν παρατηρηθεί ισόθερμες καμπύλες οργανικών ρύπων με μεγάλη έλλειψη γραμμικότητας. Προκαταρκτικές μελέτες έχουν δείξει ότι πράγματι η αλατότητα επηρεάζει τη ρόφηση ανάλογα με το μηχανισμό που παρατηρείται για κάθε είδος ροφητή. Αλλιώς επηρεάζεται η ρόφηση από την αλατότητα, όταν λαμβάνει χώρα στην επιφάνεια του ροφητή, και αλλιώς στους πόρους στο εσωτερικό του ροφητή. Η παρούσα μεταπτυχιακή εργασία περιλαμβάνει πειραματική μελέτη της ισορροπίας της ρόφησης ενός οργανικού ρύπου (του φαινανθρενίου) σε διάφορους ροφητές από το γλυκό και το θαλασσινό νερό. Οι ροφητές περιλαμβάνουν ανθρακούχα σωματίδια και ετερογενή υλικά, όπως γαιάνθρακα, λιγνίτη και θαλάσσια ιζήματα από την περιοχή του Αλιβερίου, του Λαυρίου και του Σαρωνικού κόλπου (Λουτρόπυργος) που έχουν ρυπανθεί από τα παραπάνω ανθρακούχα σωματίδια. Η αλατότητα φαίνεται να επηρεάζει σημαντικά τη ρόφηση του φαινανθρενίου σε σωματίδια λιθάνθρακα όταν τα πειράματα διεξάγονται σε σχετικά χαμηλές συγκεντρώσεις (<200 μg/L). / Until recently sorption of organic compounds onto sediments was believed to be a linear process dependent on the organic carbon fraction content. Non linear sorption and heterogeneous behavior based has been recognized the last decade. Due to salinity, various effects are observed for the different carbonaceous materials on the capacity and also on the degree of nonlinearity. Each material presents a different sorption pattern and various effects due to salinity are observed (e.g. coal sorption isotherm becomes linear in the presence of salinity whereas for lignite no significant difference is observed). In the present work, we study the sorption behavior of phenanthrene onto different sorbents in salt water. Sorbents used include carbonaceous materials, coal, lignite, and marine sediments from Aliveri, Laurio, and Saronikos gulf that are polluted with carbonaceous particles. Salinity seems to affect significantly the sorption of phenanthrene onto coal particles if the experiments are performed at concentrations lower than 200 μg/L.

abstract: Atmospheric particulate matter has a substantial impact on global climate due to its ability to absorb/scatter solar radiation and act as cloud condensation nuclei (CCN). Yet, little is known about marine aerosol, in particular, the carbonaceous fraction. In the present work, particulate matter was collected, using High Volume (HiVol) samplers, onto quartz fiber substrates during a series of research cruises on the Atlantic Ocean. Samples were collected on board the R/V Endeavor on West&ndash;East (March&ndash;April, 2006) and East&ndash;West (June&ndash;July, 2006) transects in the North Atlantic, as well as on the R/V Polarstern during a North&ndash;South (October&ndash;November, 2005) transect along the western coast of Europe and Africa. The aerosol total carbon (TC) concentrations for the West&ndash;East (Narragansett, RI, USA to Nice, France) and East&ndash;West (Heraklion, Crete, Greece to Narragansett, RI, USA) transects were generally low over the open ocean (0.36&plusmn;0.14 &mu;g C/m3) and increased as the ship approached coastal areas (2.18&plusmn;1.37 &mu;g C/m3), due to increased terrestrial/anthropogenic aerosol inputs. The TC for the North&ndash;South transect samples decreased in the southern hemisphere with the exception of samples collected near the 15th parallel where calculations indicate the air mass back trajectories originated from the continent. Seasonal variation in organic carbon (OC) was seen in the northern hemisphere open ocean samples with average values of 0.45 &mu;g/m3 and 0.26 &mu;g/m3 for spring and summer, respectively. These low summer time values are consistent with SeaWiFS satellite images that show decreasing chlorophyll a concentration (a proxy for phytoplankton biomass) in the summer. There is also a statistically significant (p<0.05) decline in surface water fluorescence in the summer. Moreover, examination of water&ndash;soluble organic carbon (WSOC) shows that the summer aerosol samples appear to have a higher fraction of the lower molecular weight material, indicating that the samples may be more oxidized (aged). The seasonal variation in aerosol content seen during the two 2006 cruises is evidence that a primary biological marine source is a significant contributor to the carbonaceous particulate in the marine atmosphere and is consistent with previous studies of clean marine air masses. / Dissertation/Thesis / M.S. Chemistry 2011

Made available in DSpace on 2015-08-20T17:10:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-04-24. Added 1 bitstream(s) on 2015-08-20T17:25:48Z : No. of bitstreams: 1 000841964.pdf: 1463703 bytes, checksum: 408f5159b85550b011090a5f648d6c32 (MD5) / Este trabalho descreve a preparação e viabilidade de sensores eletroquímicos à base de nanomateriais carbonáceos e catalisadores biomiméticos da enzima P450, visando à obtenção de sensores sensíveis e seletivos para determinação de tetraciclina. Para tal, inicialmente foram construídos sensores eletroquímicos usando pasta de carbono modificada com 10% (m/m) de MWCNT-COOH (nanotubos de carbono de paredes múltiplas funcionalizados com grupos carboxila) e 10% (m/m) de óxido de grafeno (GO). A Voltametria de pulso diferencial adsortiva com varredura anódica (VPDadVA) permitiu obter melhores resultados em solução tampão fosfato 0,1 mol L-1 (pH 7,0); potencial e tempo de acumulação de 0,2 V e 30 s, respectivamente. Sob estas condições o sensor apresentou uma faixa linear de resposta entre 1,2 x 10-5 e 1,7 x 10-4 mol L-1, sensibilidade de 1,2 x 104 (±1,0x103) μA mol L-1 e limite de detecção de 3,6 x 10-8 mol L-1. Este sensor foi aplicado na determinação de tetraciclina em urina sintética, águas de rio e medicamentos, obtendo-se recuperações com valores próximos a 100% e valores de repetibilidade em termos do desvio padrão relativo (DPR) abaixo de 6%. Na segunda etapa do trabalho, visando à obtenção de um sensor biomimético, além dos materiais nanopartículados, as pastas de carbono foram individualmente modificadas, com 11 compostos organometálicos que mimetizam o sitio ativo da enzima P450. Dentre eles, apenas a bispiridilftalocianinaferro (II), cloreto de 5,10,15,20-tetrafenil-21H,23H-porfirinaferro (III) e 1,2,3,4,8,9,10,11,15, 16,17,18,22,23,24,25-hexadecafluoro-29H,31H-ftalocianinacobalto (II) apresentaram resposta promissora usando voltametria cíclica. Entretanto, quando realizados experimentos de quantificação através de VPDadVA nas condições otimizadas, vi nenhum dos sensores mostrou respostas satisfatórias, apesar dos esforços realizados para conseguir a... / This work describes the preparation and feasibility of electrochemical sensors based on carbonaceous nanomaterials and biomimetic catalysts of the P450 enzyme, in order to obtain sensitive and selective sensors for determination of tetracycline. For this, electrochemical sensors were initially constructed using carbon paste modified with 10% (w/w) of MWCNTCOOH (carbon nanotubes multi-walled functionalized with carboxyl groups) and 10% (w/w) of graphene oxide (GO). Differential pulse with adsorptive anodic stripping voltammetry (DPadSAV) provided the best results in phosphate buffer 0.1 mol L-1 (pH 7.0) and accumulation potential and time of 0,2 V and 30 s, respectively. Under these conditions the sensor showed a linear response range between 1.2 x 10-5 and 1.7 x 10-4 mol L-1, sensitivity of 1.2 x 104 (± 1,0 x 103) A mol L-1 and detection limit of 3.6 x 10-8 mol L-1. This sensor has been applied to the determination of tetracycline in synthetic urine, river water and pharmaceutical formulations with recovery values close to 100% and repeatability in terms of relative standard deviation (RSD) below 6%. In the second stage of the work in order to obtain a biomimetic sensor, in addition to the nanoparticulate materials, carbon pastes were individually modified, with 11 organometallic compounds that mimic the active site of P450 enzyme. Among them, only bis(pyridil)phthalocyanine iron (II); 5,10,15,20-tetraphenyl-21H, 23H-porphyrin iron (III) chloride and 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H,31H-phthalocyanine cobalt (II) showed promising response using cyclic voltammetry. However, when performed experiments by VPD and DPadSAV in optimized conditions, none of the sensors showed satisfactory resposes, despite the efforts made to achieve the quantification of tetracycline. viii Showing that in this case, the these compounds did not improve the sensor response previously obtained...

abstract: Interpreting the petrogenesis of materials exposed on the surface of planets and asteroids is fundamental to understanding the origins and evolution of the inner Solar System. Temperature, pressure, fO2, and bulk composition directly influence the petrogenetic history of planetary surfaces and constraining these variables with remote sensing techniques is challenging. The integration of remote sensing data with analytical investigations of natural samples, lab-based spectroscopy, and thermodynamic modelling improves our ability to interpret the petrogenesis of planetary materials. A suite of naturally heated carbonaceous chondrite material was studied with lab-based spectroscopic techniques, including visible near-infrared and Fourier transform infrared reflectance spectroscopy. Distinct mineralogic, and thus spectroscopic, trends are observed with increasing degree of thermal metamorphism. Characterization of these spectral trends yields a set of mappable parameters that will be applied to remotely sensed data from the OSIRIS-REx science payload. Information about the thermal history of the surface of the asteroid Bennu will aid in the selection of a sampling site, ensuring OSIRIS-REx collects a pristine regolith sample that has not experienced devolatilization of primitive organics or dehydration of phyllosilicates. The evolution of mafic magma results in distinct major element chemical trends. Mineral assemblages present in evolved volcanic rocks are indicators of these processes. Using laboratory spectroscopic analyses of a suite of evolved volcanic rocks from the Snake River Plain, Idaho, I show that these evolutionary trends are reflected in the spectral signatures of ferromagenesian and feldspar minerals. The Athena science package on the Mars Exploration Rover Spirit allows for the in situ investigation of bulk chemistry, texture, and mineralogy on the surface of Mars. Using the bulk composition of the Irvine and Backstay volcanic rocks, thermodynamic modeling was performed to further constrain the formation conditions of Martian volcanics. Irvine and Backstay compositions exhibit dramatic variations in modal mineralogy with changing fO2. Using these results, I show that the observed Mini-TES spectra of Irvine and Backstay can be adequately reproduced, and additional constraints can be placed on their primary fO2. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2018

Les astéroïdes sont des vestiges datant de la formation de notre Système stellaire. Ils nous offrent une opportunité unique de comprendre la mécanique de formation d'un système planétaire habité, le Système Solaire. Une méthode de caractérisation de ces petits corps couramment utilisé est la spectroscopie en réflectance, qui permet à, depuis la Terre ou lors de missions spatiales, d'obtenir des informations sur la minéralogie de ces objets. L'objet de cette thèse est de participer à une meilleure compréhension de cette technique de caractérisation, ainsi que d'étudier, via les météorites, les processus d'altérations ayant modifiés la composition initiale. Pour ce faire nous avons utilisé différentes méthodes d'analyses sur des chondrites carbonées (qui proviennent d'astéroïdes primitifs) afin de caractériser leur chimie et leur minéralogie. Nous avons ainsi étudié les phases hydratées, la teneur en eau, la structure des silicates et l'état d'oxydation du fer de ces météorites. Toutes ces analyses combinées nous ont permis de mieux comprendre l'évolution de la minéralogie en fonction des processus d'altérations hydrothermaux. Ces études ont également permis d'apporter des contraintes quantitatives et qualitatives sur les caractéristiques contrôlant les spectres en réflectance de ces mêmes météorites. Nous avons étudié et comparé de nombreux paramètres entre eux pour permettre de quantifier l'eau et proposons celui qui nous semble le plus adapté pour quantifier les phases hydratés à la surface des petits corps sombres du Système Solaire. / Asteroids are relics from the early Solar System. Some of them are extremely primitive and can help in understanding the mechanic of Solar System formation, and ultimately the scenario that led to the formation of a habited planetary system. Reflectance spectroscopy is now a classical and useful method to analyze asteroid composition from the Earth or during space mission. In this PhD thesis, we tried to improve our understanding of the spectral properties of asteroids by looking at naturally delivered fragments, meteorites. We have used different analytical methods on carbonaceous chondrites (pieces of primitive asteroids) to characterized their chemical and mineralogical composition. We studied the nature of hydrated phases, water budget, phyllosilicate structures and the speciation of iron on these meteorites. All these analyses permit an improved understanding of the transformation of the mineralogy by parent body (asteroidal) alteration. Furthermore, these analyses provide quantitative and qualitative constraints to understand the factors controlling the reflectance measurement performed on the same meteorite. We compared different analytical parameters to quantify the water abundance and suggest a method to quantify hydrated phases on dark asteroids.