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 master thesis was to investigate the mechanical properties of ExpandedPolystyrene (EPS) through experimental testing. The strain was measured on thespecimen’s surface with Digital Image Correlation (DIC), in order to investigate howthe first principal strain at fracture initiation depends on the loading of the material.To impose different loading conditions various tests were performed, such as biaxialtension-compression, uniaxial tension and bending tests. The study was done withfour densities of EPS, 35, 50, 75 and 100 g/L. To investigate how strain and stressat fracture initiation depend on temperature, the bending tests were performed atthree different temperatures, -20, 20 and 50 °C. All tests were performed in the SolidMechanics lab at KTH, Stockholm. For every experiment, five repetitions were madeto reduce the influence of the inhomogeneous microstructure of EPS and the stochasticbehaviour of fracture mechanics. The results indicate that the fracture initiation straindecreases with increasing density of EPS, while the fracture strength increases withincreasing density of EPS. Further, the results indicate that the loading conditions havean influence on the fracture initiation strain. / Målet med detta examensarbete var att undersöka materialegenskaper för EPS genomatt utföra experimentell testning. Töjningen mättes på provbitarnas yta med hjälp avDIC-teknik, för att undersöka hur första huvudtöjningen vid sprickinitiering beror påbelastningen av materialet. För att belasta material på olika sätt utfördes olika tester,såsom enaxligt drag, biaxiellt drag och tryck samt böjtester. Testerna gjordes med fyradensiteter av EPS, 35, 50, 75 and 100 g/L. För att undersöka hur töjning och kraft vidsprickinitiering beror på temperatur utfördes böjtesterna vid tre temperaturer, -20,20 and 50 °C. Alla tester utfördes på institutionen för hållfasthetslära vid KungligaTekniska högskolan. Varje experiment repeterades fem gånger för att minimerainverkan av den inhomogena mikrostrukturen hos EPS. Resultaten tyder på attbrottinitieringstöjningen minskar med ökande densitet av EPS, medan brottlastenökar med ökande densitet av EPS. Vidare indikerar resultaten att belastningen har eninverkan på brottinitieringstöjningen.

We have attempted adaptive optics (AO) imaging of planets around nearby stars in the L' and M bands, using the Clio instrument on the MMT. The MMT AO system, with its deformable secondary mirror, offers uniquely low background AO-corrected images in these bands. This allowed us to explore a wavelength regime that has not been well utilized in searches for extrasolar planets, but offers some advantages over the more commonly used shorter-wavelength H band regime. We have taken deep L' and M band images of the interesting debris disk stars Vega and ϵ Eri. Our observations of ϵ Eri attain better sensitivity to low mass planets within 3 arcseconds of the star than any other AO observations to date. At 1.7 arcsec, the maximum separation of the known planet ϵ Eri b, our M band sensitivity corresponds to objects only 9-16 times brighter than the predicted brightness of this planet. M is by far the most promising band for directly imaging this planet for the first time, though Clio would require a multi-night integration. We have carried out a survey of 50 nearby stars, using mostly the L' band. The survey objective was to determine whether power law fits to the statistics of planet mass m and orbital semimajor axis a from radial velocity (RV) surveys apply when extrapolated to orbital radii beyond the outer limits of RV sensitivity. Given dN/dm ~ m^{-1.44}, our survey null result rules out dN/da ~ a^{-0.2} extending beyond 155 AU, or dN/da constant extending beyond 70 AU, at the 95% confidence level. We have not placed as tight constraints on the planet distributions as the best H band surveys. However, we have probed older planet populations and by using a different wavelength regime have helped diversify results against model uncertainties. We have developed careful and well-tested observing, image processing, sensitivity analysis, and source detection methods, and helped advance L' and M band AO astronomy. These wavelengths will become increasingly important with the advent of new giant telescopes sensitive to interesting, low-temperature planets with red H-L' and H-M colors.

Variovorax paradoxus EPS is a gram-negative rod isolated from the sunflower rhizosphere at CSUSB. Preliminary research has shown that Variovorax paradoxus EPS has anti-staphylococcal activity in liquid and solid co-culture. Anti-staphylococcal activity of Wild type and V. paradoxus EPS 𝚫4519 on 0.5% YE agar with embedded S. aureus AH1710 supports the idea that a soluble molecule is responsible for this activity, as the agar acted as a physical barrier between V. paradoxus EPS and S. aureus colonies. Preliminary genetic analysis of V. paradoxus EPS identified three loci that suitable candidates for the synthesis of a potential anti-staphylococcal small molecule. Preliminary data failed to detect expression at two of the three identified loci and a strain with a mutation at the third locus continues to produce anti-staphylococcal activity. We hypothesize that the microbial agent is expressed at a different locus or loci that have not yet been identified. These gene products are responsible for the synthesis of the microbial agent and are controlled by exposure to Staphylococcus aureus. Optimal growth conditions were identified for V. paradoxus EPS and S. aureus to demonstrate the formation of a zone of inhibition on Tryptic Soy Agar. The use of a V. paradoxus EPS Δ 4519 transposon library at optimal growth conditions allowed us candidate mutants with altered antimicrobial activity phenotypes. We identified 28 insertion sites that resulted in altered antimicrobial activities, which will allow us to identify the genes involved in this biosynthetic pathway.

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The impact of cranberry juice was investigated with respect to the initial adhesion of three isogenic Burkholderia cepacia bacteria with different extracellular polymeric substance (EPS) producing capacities: a wild-type cepacian EPS producer PC184, mutant bacteria PC184rml with reduced EPS production, and PC184bceK with a deficiency in EPS production. Adhesion experiments demonstrated that in the presence of cranberry juice, the adhesive capacity of PC184 was largely reduced, while cranberry juice had little impact on the adhesion of either mutant. Thermodynamic modeling supported results from adhesion experiments. For PC184, the surface free energy change Gadh switched from negative in the absence of cranberry juice to positive when cranberry juice was added. Surface force apparatus (SFA) and scanning electron microscopy (SEM) studies demonstrated strong adsorption of cranberry juice components to bacterial EPS. It was concluded that cranberry juice components could impact bacterial initial adhesion by adhering to EPS and impairing bacterial adhesive capacity. / Environmental Engineering

Empirical studies have found that managers choose debt rather than equity to avoid EPS dilution and buy back outstanding shares to boost EPS, I thus explore the resulting effect of EPS on leverage. A firm’s leverage is negatively influenced by the level of its EPS. I also find that fluctuations in EPS have large effects on leverage and these effects persist for at least a decade. Besides, the negative impact of EPS on leverage becomes much stronger after the passage of SOX, in which period managers engage in more actions of debt-equity choices or stock repurchases with the sole purpose of manipulating EPS. Furthermore, managers’ equity incentives and corporate governance are two economic mechanisms through which EPS negatively influences leverage.

Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2016-01-06T16:33:02Z No. of bitstreams: 2 aline_nogueira_alves_santiago.pdf: 3992386 bytes, checksum: b8ec3c32c9f964b34275b2319b6b3edf (MD5) license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2016-01-07T11:54:26Z (GMT) No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) aline_nogueira_alves_santiago.pdf: 3992386 bytes, checksum: b8ec3c32c9f964b34275b2319b6b3edf (MD5) / Made available in DSpace on 2016-01-07T11:54:31Z (GMT). No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) aline_nogueira_alves_santiago.pdf: 3992386 bytes, checksum: b8ec3c32c9f964b34275b2319b6b3edf (MD5) Previous issue date: 2015 / Um anodo perme?vel a fluido constitu?do por filme fino de di?xido de estanho dopado com antim?nio (Sb-SnO2) foi preparado por decomposi??o t?rmica sobre suporte de tela de a?o ASTM 316 e utilizado em reator eletroqu?mico do tipo filtro-prensa. O filme e o p? do ?xido foram investigados pelas t?cnicas de energia dispersiva de raios-X (EDX), difratometria de raios-X (DRX) e microscopia eletr?nica de varredura (MEV). O estudo do EDX indicou uma raz?o efetiva Sb/Sn maior que a nominal devido a volatiliza??o do Sn. O DRX revelou que o SnO2 est? presente na estrutura rutila, n?o sendo verificado a presen?a de picos relacionados ao ?xido de antim?nio devido sua baixa concentra??o. O estudo de MEV revelou a forma??o de filme compacto e n?o poroso, com presen?a de cristalitos superficiais. Para a caracteriza??o eletroqu?mica do anodo Sb-SnO2 foi realizado estudo de voltametria c?clica, sendo obtido a partir da curva voltam?trica uma baixa densidade superficial de carga, ou seja, o eletrodo ? de morfologia compacta. A curva de polariza??o revelou que o sobrepotencial para a rea??o de desprendimento de oxig?nio (RDO) ? de aproximadamente 1,75 V/ECS. O anodo Sb-SnO2 alojado numa c?lula filtro-prensa na condi??o de ?zero-gap? foi utilizado na degrada??o eletroqu?mica individual dos f?rmacos Diclofenaco S?dico e Paracetamol (Acetominofeno) na total aus?ncia de eletr?litos l?quidos. Os fatores que influenciam a taxa de degrada??o, tais como a densidade de corrente aplicada (5?25 mA/cm2) e a concentra??o inicial dos f?rmacos (30?70 mg/L) foram avaliados. A degrada??o dos f?rmacos seguiu a cin?tica de pseudo-primeira ordem, sendo monitorada por an?lise da demanda qu?mica de oxig?nio (DQO), cromatografia l?quida de alta efici?ncia (CLAE) e espectros na regi?o do ultravioleta-vis?vel (Uv/Vis). Foram verificadas taxas de degrada??es superiores a 80% ap?s 3,5 h de rea??o com a gera??o de subprodutos. O grau de instabilidade do eletrodo foi avaliado em fun??o do seu tempo de uso. O anodo Sb-SnO2 apresentou uma boa efic?cia para a remo??o dos f?rmacos Diclofenaco S?dico e Paracetamol (Acetominofeno) dissolvidos em ?guas, mas com um curto tempo de vida ?til. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2015. / ABSTRACT A fluid-permeable thin film anode composed by tin dioxide doped with antimony (Sb-SnO2) was prepared by thermal decomposition onto a ASTM 316 stainless steel screen support, and applied in a filter-press electrochemical reactor. The film and the oxide powder were investigated by the energy dispersive x-ray (EDX), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The EDX study revealed an effective Sb/Sn ratio higher than the nominal one due to the volatilization of Sn. The XRD revealed that SnO2 is present as a rutila structure, not being verified the occurrence of peaks related to the antimony oxide due its low concentration. SEM analysis showed the formation of compact and non-porous film, with the presence of surface crystallites. For the electrochemical characterization of the Sb-SnO2, it was carried out a cyclic voltammetry study, being obtained from the voltammetric curve a low surface charge density, i.e., the electrode has a compact morphology. The polarization curve showed that the overpotential for the oxygen evolution reaction (OER) is about 1.75 V/SCE. The Sb-SnO2 anode housed in a filter-press cell in the zero-gap condition was applied on the electrochemical degradation of the Sodium Diclofenac and Paracetamol (acetominophen) drugs in the total absence of liquid electrolytes. Factors affecting the degradation rate, such as the applied current density (5?25 mA/cm2) and the initial concentration of drugs (30?70 mg/L) were evaluated. The degradation of drugs followed the pseudo first-order kinetics, being monitored by analysis of the chemical oxygen demand (COD), high performance liquid chromatography (HPLC) and spectra in the ultraviolet-visible (UV/Vis) region. It was verified degradation rates higher than 80% after 3.5 h of reaction with the formation of byproducts. The degree of electrode instability was evaluated as a function of its use time. The Sb-SnO2 anode exhibited a good efficiency for the removal of the drugs Diclofenac and Paracetamol (acetominophen) dissolved in water, but with a short service life.