Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, 2006. / Submitted by Érika Rayanne Carvalho (carvalho.erika@ymail.com) on 2009-10-15T01:07:07Z No. of bitstreams: 1 LEONARDO MONTEIRO RIBEIRO.pdf: 1295480 bytes, checksum: 5da1d1be81259342fa613ba8e3ae2387 (MD5) / Approved for entry into archive by Tania Milca Carvalho Malheiros(tania@bce.unb.br) on 2009-10-15T12:38:52Z (GMT) No. of bitstreams: 1 LEONARDO MONTEIRO RIBEIRO.pdf: 1295480 bytes, checksum: 5da1d1be81259342fa613ba8e3ae2387 (MD5) / Made available in DSpace on 2009-10-15T12:38:52Z (GMT). No. of bitstreams: 1 LEONARDO MONTEIRO RIBEIRO.pdf: 1295480 bytes, checksum: 5da1d1be81259342fa613ba8e3ae2387 (MD5) Previous issue date: 2006-06-12 / O maracujazeiro-azedo (Passiflora edulis Sims f. flavicarpa Deg.) é uma das principais frutíferas brasileiras e seu cultivo apresenta boas perspectivas de expansão. O desenvolvimento da cultura tem sido dificultado por doenças, especialmente a doença do endurecimento dos frutos, causada pelo Cowpea aphid-borne mosaic virus (CABMV). A eliminação de vírus pela cultura de tecidos tem sido uma alternativa viável para muitas espécies e pode contribuir para a propagação vegetativa de genótipos superiores. O presente trabalho foi realizado com o objetivo de estudar a organogênese in vitro em plantas de maracujazeiro amarelo infectadas com o Cowpea aphid-borne mosaic virus (CABMV) e avaliar o efeito de meios de cultura utilizados sobre o ponto da enxertia na microenxertia ex vitro visando a eliminação do vírus CABMV. No estudo da organogênese foram avaliados cinco acessos: MAR-2003, MAR-2021, MAR-2024, MAR-2048, Rubi Gigante (RG) e quatro fontes de explantes: ápice caulinar, segmento internodal, segmento nodal e fragmento foliar. Foi utilizado para indução o meio MS suplementado por 2 mg.L-1 de 6-benzilaminopurina (BAP). O segmento nodal apresentou melhor desempenho no cultivo enquanto os piores resultados foram obtidos com o fragmento foliar. Os acessos apresentaram comportamento semelhante em relação ao percentual de explantes organogênicos e à produção de brotos. Foram observados em cortes histológicos meristemóides em explantes de nó e ápice. No trabalho envolvendo a eliminação de vírus por microenxertia ex vitro, ápices caulinares provenientes de plantas do acesso MAR-2050 infectadas foram microenxertados em plântulas obtidas pela germinação de sementes e cultivadas em substrato comercial em condição de laboratório. Foram conduzidos experimentos com a microenxertia realizada no hipocótilo e no epicótilo e testados cinco meios de cultura como adjuvantes, aplicados no ponto da enxertia. O índice de pegamento médio foi de 27,22 % quando a microenxertia foi realizada no hipocótilo e 32,22 % quando realizada no epicótilo. Na microenxertia realizada no hipocótilo não houve efeito da aplicação de meios de cultura ou reguladores de crescimento. Na microenxertia realizada no epicótilo o meio MS suplementado com 3% de sacarose, 10 mg.L-1 de tiamina; 1 mg.L-1 de piridoxina; 1 mg.L-1 de ácido nicotínico; 100 mg L-1 de mio-inositol e 2 gL-1 de Phytagel, (meio básico), acrescido de 0,1 mg.L-1 de ácido 3-indolbutírico (AIB) e 1 mg.L-1 de 6-benzilaminopurina (BAP) proporcionou 53,3% de pegamento e foi superior aos demais tratamentos, com exceção do tratamento meio básico suplementado com 2 mg L-1 xvi de BAP. O mesmo tratamento ocasionou maior desenvolvimento das brotações. O inicio da formação da conexão vascular entre o explante e o porta-enxerto foi observada aos 15 dias e estava estabelecida aos 30 dias. A indexação realizada pelo teste ELISA (Enzyme Linked Imunosorbent Assay) indireto aos 80 a 100 dias da microenxertia mostrou que 93 % das plantas testadas não apresentavam vírus detectável. __________________________________________________________________________________________ ABSTRACT / The sour passion fruit plant (Passiflora edulis Sims f. flavicarpa Deg.) is one of the most important Brazilian fruitbearings and its cultivation presents good perspectives of expansion. The culture development has been made more difficult by diseases, specially the fruit hardening disease, caused by the Cowpea aphid-borne mosaic virus (CABMV). The virus elimination by tissue culture has been a viable alternative for many species and can contribute to the superior genotypes vegetative propagation. This work was performed with the objective of studying the in vitro organogenesis in yellow passion fruit plants infected with the Cowpea aphid-borne mosaic virus (CABMV) and assessing the effect of the culture medium used over the grafting spot in ex vitro micrografting aiming at eliminating the CABMV virus. In the organogenesis study five accessions were evaluated: MAR-2003, MAR-2021, MAR-2024, MAR-2048, Rubi Gigante (RG) and four sources of explants: cauline apex, internodal segment, nodal segment and foliar fragment. It was used for induction the medium MS supplemented by 2 mg.L-1 6-benzylaminopurine (BAP). The nodal segment presented the best cultivation performance while the worst results were obtained with the foliar fragment. The accessions presented similar behavior in relation to the percentage of organogenic explants and to the production of shoots. It was observed in histological cuts meristemoids in nodal and apex explants. In the work involving the virus elimination through ex vitro micrografting, stem apexes originated from MAR 2050 accession infected plants were micrografted in seedlings obtained through the germination of seeds and cultivation in commercial substract under laboratory conditions. Experiments were conducted with the micrografting performed on the hypocotyl and epicotyl. Five culture media were tested as adjuvant, applied at the grafting spot. The average rate of setting was 27.22 % when the micrografting was performed on the hypocotyl and 32.22 % when performed on the epicotyl. The micrografting performed on the hypocotyl showed no effects with the application of culture media or growth regulators. The micrografting performed on the epicotyl and the MS medium supplemented with 3% sucrose, 10 mg.L-1 thiamine; 1 mg.L-1 pyridoxine; 1 mg.L-1 nicotinic acid; 100 mg L-1 mio-inositol and 2 gL-1 Phytagel, (basic medium), in addition to 0.1 mg.L-1 3-indolbutiric acid (AIB) and 1 mg.L-1 6- benzylaminopurine (BAP) provided 53.3% setting in the micrografting and was superior to xviii the other treatments, excepting the basic medium treatment supplemented with 2 mg L-1 BAP. The same treatment provided larger shoots development. The beginning of the vascular connection formation between the participants was observed within 15 days and was established in 30 days. The indexation performed by the ELISA (Enzyme Linked Imunosorbent Assay) indirect test within 80 to 100 days of the micrografting showed that 93 % of the plants tested did not present detectable virus.

Dissertação (mestrado)-Universidade de Brasília, Instituto de Ciências Biológicas, Departamento de Botânica, 2006. / Submitted by Mariana Fonseca Xavier Nunes (nanarteira@hotmail.com) on 2010-09-25T19:44:46Z No. of bitstreams: 1 2006-Emanuel Felipe Medeiros Abreu.pdf: 2068694 bytes, checksum: 177c85e4d31538b0a5838f1eea46ccd9 (MD5) / Approved for entry into archive by Daniel Ribeiro(daniel@bce.unb.br) on 2010-10-08T22:55:43Z (GMT) No. of bitstreams: 1 2006-Emanuel Felipe Medeiros Abreu.pdf: 2068694 bytes, checksum: 177c85e4d31538b0a5838f1eea46ccd9 (MD5) / Made available in DSpace on 2010-10-08T22:55:43Z (GMT). No. of bitstreams: 1 2006-Emanuel Felipe Medeiros Abreu.pdf: 2068694 bytes, checksum: 177c85e4d31538b0a5838f1eea46ccd9 (MD5) / A mio-inositol-1L-fosfato sintase (MIPS) é a enzima responsável pela conversão de D-glucose 6-fosfato a 1-L-mio-inositol-1-fosfato, primeiro e limitante passo na via de síntese de todos os compostos derivados do inositol. Os inositol-fosfolipídios, assim como outros compostos derivados do inositol, têm um papel fundamental no tráfico de membrana e rotas de sinalização, estocagem e transporte de auxinas, biossíntese de ácido fítico e parede celular, e produção de moléculas relacionadas ao estresse. No presente trabalho, nós caracterizamos um cDNA do gene MIPS de sementes de Passiflora edulis f. flavicarpa (PeMIPS1) e investigamos a sua expressão espacial, bem como mudanças na transcrição em plantas submetidas ao estresse causado pelo frio e calor Para estas análises, uma seqüência do cDNA do gene MIPS foi isolada por PCR (5e 3RACE) e os níveis dos transcritos foram analisados usando RT-PCR semi-quantitativo durante o desenvolvimento da semente, óvulo, grão-de-pólen, folha, caule, pétala, glândula foliar e em resposta ao estresse. A seqüência completa do cDNA do gene PeMIPS foi isolada, clonada e caracterizada. Adicionalmente, o número de cópias do gene PeMIPS clonado foi determinado por análise de Southern blot no genoma de Passiflora edulis, Passiflora eichleriana, Passiflora caerulea, Passiflora nitida e Passiflora coccinea. Esta análise indicou que o DNA genômico pode conter diversas seqüências de outros genes MIPS, mas uma única cópia do gene PeMIPS clonado foi encontrado no genoma de P. edulis, P. eichleriana, P. caerulea, P. nitida e P. coccinea. A análise da expressão por RT-PCR revelou a presença de transcritos de PeMIPS em óvulos, grãos-de-pólen, folhas e durante os estágios do desenvolvimento da semente, com um pico nove dias após a polinização. Verificou-se ainda, que o gene PeMIPS é diferencialmente regulado sob condições de estresse causado pelo frio e calor em resposta à presença ou ausência de luz. Portanto, o presente trabalho sugere que o PeMIPS tem um importante papel no estabelecimento de programas de desenvolvimento e na resposta das plantas à mudanças ambientais. _________________________________________________________________________________ ABSTRACT / Myo-inositol-1L-phosphate synthase (MIPS) catalyses the conversion of D-glucose 6-phosphate to 1-L-myo-inositol-1-phosphate, the first and rate-limiting step in the biosynthesis of all inositol-containing compounds. Inositol phospholipids play a vital role in membrane trafficking and signalling pathways, auxin storage and transport, phytic acid biosynthesis, cell wall biosynthesis, and production of stress-related molecules. In the present study, we characterised an MIPS cDNA from developing Passiflora edulis f. flavicarpa (PeMIPS1) seeds and investigated its spatial and differential expression, as well as changes in its transcription during exposure of growing plants to cold and heat stresses. MIPS encoding gene was isolated by PCR methods and the transcript levels were examined using semi-quantitative RT-PCR during seed development, ovules, pollen grains, stem, leaves, petals, leaf gland and in response to heat and cold stress. In addition, the copy number of the cloned PeMIPS gene in the genome of Passiflora edulis, Passiflora eichleriana, Passiflora caerulea, Passiflora nitida and Passiflora coccinea was determined by Southern blot analyses. Full-length cDNA clone of the PeMIPS1 from P. edulis was isolated and characterised. Southern blot analyses indicated that the genomic DNA might have diverse sequences of MIPS-encoding genes and one copy of the cloned PeMIPS1 gene in the genomes of P. edulis, P. eichleriana, P. caerulea, P. nitida and P. coccinea. RT-PCR expression analyses revealed the presence of PeMIPS1 transcripts in ovules, pollen grains and leaves, and during the seed developmental stages, where it was observed a transcriptional peak at the ninth days after pollination. The PeMIPS1 gene is differentially regulated under cold- and heat-stress, presenting a light-responsive transcription. Experimental data suggest that PeMIPS1 plays an important role in the establishment of developmental programs and during the response of plants to environmental changes. The PeMIPS1 is differentially regulated during cold and heat stress, presenting a light-response pattern, indicating that the extension of the inositol pathway is an important aspect for environmental stress response.

abstract: Mass spectrometric analysis requires that atoms from the sample be ionized in the gas phase. Secondary ion mass spectrometry achieves this by sputtering samples with an energetic primary ion beam. Several investigations of the sputtering and ionization process have been conducted. Oxygen is commonly used in secondary ion mass spectrometry (SIMS) to increase ion yields, but also can complicate the interpretation of SIMS analyses. An 18O implant in silicon has been used to quantify the oxygen concentration at the surface of sputtered silicon in order to study the dependence on oxygen of several sputtering and depth profile phenomena. The ion yield dependence of trace elements in silicon on the surface oxygen concentration is a function of the ionization potential of the element. The ion yield is high and unaffected by oxygen for elements with low ionization potential and ranges over several orders of magnitude for elements with high ionization potential. Depth resolution in sputter profiles has been shown to be degraded by the presence of oxygen, the mechanism of this effect has been investigated using an 18O implant to quantify oxygen levels and it is shown that the process does not appear to be a consequence of surface oxide formation. Molecular ions are a source of mass interference in SIMS analysis, and multiply charged atomic ion signals might be interference-free due to the possible instability of multiply-charged molecular ions. Sputtered SiH2+, AlH2+, BeH2+, Mo22+ and Mg22+ ions have been observed and appear surprisingly stable. The formation mechanism of some of these species has been explored. / Dissertation/Thesis / Ph.D. Chemistry 2012

Hydrogen causes defects, for which aluminiurn alloy products are rejected. The behaviour of hydrogen in aluminium-magnesium-silicon alloy extrusion ingots, has been studied throughout the course of manufacture from freshly reduced aluminium. It is shown that hydrogen in the liquid metal is produced by temperature-dependent reaction between the metal and water vapour in the atmosphere. As the metal is received from the reduction cells, its temperature is -850 'C and its hydrogen content, >0.4 cm3/100 g, is too high for casting sound ingots. The metal is transferred first to a so-called melting furnace, where it is alloyed and stirred, thence to a holding furnace, where the composition is adjusted, the metal is degassed by gas sparging and allowed to settle before casting. The metal cools throughout these operations and as the temperature falls, the calculated value for the hydrogen content in equilibrium with the atmosphere falls in response to the reduced hydrogen solubility. The actual hydrogen content of the metal exhibited marked hysteresis in following the equilibrium value. Significant reduction of the hydrogen content occurred only when the metal was agitated. The hydrogen content never fell below the equilibrium value even during the nominal degassing operation, leading to the conclusion that gas sparging in a furnace does not positively remove hydrogen but only assists the equilibration. The hot-top DC casting process yielded a 8 m x 0.18 m diameter ingot with a virtually uniform hydrogen content. When this ingot was homogenised by heating it to 590˚C in a 7h cycle, a significant proportion of the hydrogen content was lost from the surface zone. By matching the loss to a theoretical model assuming diffusion control, it was shown that the loss of hydrogen is attenuated by trapping in micropores. The effects of simulated industrial atmospheres on the loss or absorption of hydrogen by the solid alloy were investigated in an extended series of laboratory heat-treatments. The interaction of the metal with these atmospheres was found to be determined by the nature of the oxide films formed and therefore the films were investigated by XPS and SIMS surface analysis techniques. In clean atmospheres the absorption or loss of hydrogen was determined by the balance between inward migration of protons and outward diffusion of hydrogen atoms through the oxide. Pollution of the air by chlorine or especially sulphur stimulated hydrogen absorption to a degree which seriously damaged the metal by pore growth. These effects are explained by modified compositions and structures in the surface oxide.

Hard nanostructured TiAlN coatings have gained high importance in the field of protective tribological coatings. Nevertheless, their use regarding high temperature (>800°C) applications such as dry high speed machining still remains a challenge. Addition of elements such as Ta or Y has shown a beneficial impact on these properties. But for a better performance of these coatings, an in-depth understanding of their oxidation and wear mechanisms over a wider range of temperatures is needed which is currently unavailable in the literature. This work investigated the wear and oxidation properties of AlTiTaN hard coatings deposited by reactive magnetron sputtering at a substrate temperature of 250°C. Depending on process conditions, coatings with a preferential crystallographic orientation of cubic {111} or {200} with a columnar microstructure were observed. The oxidation and wear mechanisms for these coatings were investigated between 700°C and 950°C in air for various test durations. Further, the influence of Y doping in AlTiTaN coating was also studied.By combining Dynamic-Secondary Ion Mass Spectrometry ,X-ray diffraction (XRD) and Transmission Electron Microscopy measurements, it was demonstrated that a single amorphous oxide layer comprising of Ti, Al and Ta oxides formed at 700°C became a bilayer composed of a crystalline Al rich layer (protective Al2O3) and a Ti/Ta rich oxide layer at 900°C. The oxidation mechanism was governed primarily by inward diffusion of O at 700°C while from 800°C onwards outward diffusion of Al and inward diffusion of O controlled the reaction rate. A correlation between the oxidation kinetics and wear mechanism of AlTiTaN coatings, investigated at 700°, 800° and 900°C, was established. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

Les batteries lithium-ion sont largement utilisées comme source d'énergie pour les appareils électroniques portables. L'oxyde de fer (principalement α-Fe2O3), l'un des oxydes de métal de transition les plus important, a suscité l’intérêt scientifique depuis qu'il a été reporté comme matériau d'anode pour les batteries lithium-ion en raison de sa capacité théorique élevée (1007 mAh g-1), de son respect de l'environnement, de son abondance et de son faible coût. Dans cette thèse, une électrode modèle en couche mince d'oxyde de fer a été préparée par simple oxydation thermique à 300 °C dans l'air d'un substrat de fer métallique pur, utilisé aussi comme collecteur de courant. Une variété de techniques d'analyse, électrochimiques (CV, EIS et cyclage galvanostatique), spectroscopiques (XPS, ToF-SIMS) et microscopiques (MEB et AFM), ont été mises en oeuvre pour étudier les mécanismes réactionnels et la chimie de surface de l'oxyde de fer à différents stades de lithiation/délithiation et cyclage. / Lithium-ion batteries (LIBs) are widely used as power sources for portable electronic devices. Iron oxide (mainly α-Fe2O3), as one of the most important transition metal oxide, has attracted attention due to its high theoretical capacity (1007 mAh g-1), environmental friendliness, abundance and low cost since reported as anode material for LIBs. In this thesis, an iron oxide thin film model electrode was prepared by simple thermal oxidation of pure metallic iron substrate at 300 oC in air, also used as a current collector. Electrochemical methods (CV, EIS and galvanostatic cycling) were combined with surface (XPS, ToF-SIMS) and microscopic (SEM, AFM) analytical techniques to investigate the reaction mechanisms and the surface chemistry of the iron oxide thin film at different stages of lithiation/delithiation and upon cycling.

Ce travail de thèse avait pour objectif de développer une méthode basée sur l’étude de la composition isotopique du soufre (δ 34S) permettant de déterminer l’origine, biotique/abiotique, des sulfures de fer au sein des couches de produits de corrosion (CPC). Puis, il s’agissait d’appliquer la méthodologie développée à des systèmes réels afin de déterminer les mécanismes de formation de ces sulfures de fer. Des méthodes d’analyse isotopique du soufre adaptées aux liserés de sulfures de fer micrométriques observés dans les systèmes réels ont été développées en nanoSIMS et ToF-SIMS. L’étude de sulfures de fer formés en milieu carbonaté anoxique en présence, ou non, de bactéries sulfato-réductrice a permis de valider l’emploi de ces méthodes pour la détermination de l’origine des sulfures de fer. L’application de ces méthodes isotopiques couplées à la caractérisation des sulfures de fer dans les systèmes réels a mis en évidence 2 faciès. Le faciès 1 pour lequel les sulfures de fer sont situés en externe de la CPC. Ils résultent de la migration des ions Fe2+ produits au niveau du métal jusqu’aux zones riches en ions S2- d’origine biotique. Les vitesses de corrosion y sont inférieures à 20 μm/an pour les systèmes de laboratoire et à 5 µm/an pour les objets archéologiques. Et le faciès 2 pour lequel la forte présence de phases conductrices dans la CPC entraîne une délocalisation des électrons, conduisant à la migration des ions S2- d’origine biotique vers le métal où ils précipitent sous forme de sulfures de fer. Ce faciès présente de fortes avancées de corrosion locales (200 µm) qui seraient dues à l’accumulation de phénomènes de corrosion par les chlorures et de biocorrosion. / The first goal of this project was to develop a methodology based on the study of the sulfur isotopic composition enabling the determination of iron sulfides origin, biotic or abiotic, within the corrosion products layers (CPL). Then, the aim was to apply this methodology to real corrosion systems in order to determine the mechanisms of iron sulfides formation. Sulfur isotopic analyses methodologies, adapted to micrometric iron sulfides layers observed in real corrosion systems, were developed in nanoSIMS and ToF-SIMS. The study of iron sulfides formed in anoxic carbonated medium with or without sulphate-reducing bacteria validated the use of these methods for the determination of iron sulfides origin. The application of these methods coupled with the precise characterization of irons sulfides formed in the real corrosion systems show two kind of corrosion pattern. In pattern 1, the iron sulfides are localized in the external part of the CPL. They result from the Fe2+ migration from the metal surface to areas rich in biotic S2-. In this pattern, corrosion rates are lower than 20 μm/year for laboratory systems, and lower than 5 μm/year for archaeological objects. In pattern 2, the large presence of conductive phases in the CPL results in the delocalization of electrons, and so a disequilibrium of the charges at the metal’s surface. That leads to the migration of biotic S2- in the CPL till the metal where they precipitate in iron sulphides. This pattern shows high corrosion rates (~100 μm/an) that might be resulting from the accumulation of biocorrosion and chloride corrosion mechanisms.

Commercial usage of social networking is one of the most discussed topic in marketing these days. There are two general ways how to use social network -- to built communities of social networks' users and to advertise in classic display advertising. Czech companies do not place social network to their communication mix so often as foreign ones. They still have to learn how to create the most effective strategy and how to communicate with users. The most important is the activity and interaction. Only then the campaign can reach the communication goals.

In this article, we document a detailed analytical characterisation of zircon M127, a homogeneous 12.7 carat gemstone from Ratnapura, Sri Lanka. Zircon M127 has TIMS-determined mean U-Pb radiogenic isotopic ratios of 0.084743 +/- 0.000027 for Pb-206/U-238 and 0.67676 +/- 0.00023 for Pb-207/U-235 (weighted means, 2s uncertainties). Its Pb-206/U-238 age of 524.36 +/- 0.16 Ma (95% confidence uncertainty) is concordant within the uncertainties of decay constants. The delta O-18 value (determined by laser fluorination) is 8.26 +/- 0.06 parts per thousand VSMOW (2s), and the mean Hf-176/Hf-177 ratio (determined by solution ICP-MS) is 0.282396 +/- 0.000004 (2s). The SIMS-determined delta Li-7 value is -0.6 +/- 0.9 parts per thousand (2s), with a mean mass fraction of 1.0 +/- 0.1 mu g g(-1) Li (2s). Zircon M127 contains similar to 923 mu g g(-1) U. The moderate degree of radiation damage corresponds well with the time-integrated self-irradiation dose of 1.82 x 10(18) alpha events per gram. This observation, and the (U-Th)/He age of 426 +/- 7 Ma (2s), which is typical of unheated Sri Lankan zircon, enable us to exclude any thermal treatment. Zircon M127 is proposed as a reference material for the determination of zircon U-Pb ages by means of SIMS in combination with hafnium and stable isotope (oxygen and potentially also lithium) determination.

This thesis is devoted to the behavior of heavy metals in gettering multilayers made of polysilicon and silicon oxide.