Innerhalb des Zeitraumes 2002 bis 2004 wurden in Berlin Untersuchungen zur Nahrungsökologie verschiedener Vogelarten durchgeführt, wobei auch die Konsequenzen wie der Fortpflanzungserfolg analysiert wurden. Neben der Aufnahme der Brutvogel- (2002) und Wintervogelgemeinschaft (2002/2003) auf fünf Pf à ca. 20 ha entlang eines Urbangradienten, wurden die Arten Blaumeise, Grünling, Haussperling und Turmfalke speziell untersucht. Auf den fünf Pf, die sich hinsichtlich Baustruktur, Flächennutzung und Vegetationsanteil unterschieden, wurden 35 Brutvogelarten festgestellt. Anhand der Artenzahlen ist deutlich ein Urbangradient zu erkennen: Das Stadtzentrum (Ze) wies 12, das Gewerbegebiet (Ge) 15, die Hochhaussiedlung (Ho) 17, die Einfamilienhaussiedlung (Eh) 18 und der Park (Pa) 28 Arten auf. Im Verlauf der Wintervogelkartierung wurden insgesamt 3763 Individuen in 30 Arten registriert. Im Pa wurde bei der Blaumeise der höchste Reproduktionserfolg mit knapp 5,9 Ausgeflogenen/Brut festgestellt. Anhand des Zustandes der Nestlinge und des Fortpflanzungserfolgs sowie durch die Dokumentation des Fütterungsverhaltens der Altvögel anhand von Camcorderaufnahmen wurde deutlich, dass das Nahrungsangebot für die Meisen im Pa am besten war. Der carnivore Turmfalke wurde 2002 bis 2004 unabhängig von den fünf Pf an zehn Nistkastenstandorten untersucht, die in drei unterschiedlichen Zonen lagen: City (Ci), Mischgebiet (Mi) und ländliche Zone (LZ). Als Besonderheit wurden in jedem Nistkasten in der Ci in jedem Jahr anthropogene Nahrungsreste, z. B. Kotelettknochen, gefunden, was zeigt, dass sich der Turmfalke, neben der Nutzung von Gebäuden als Nistplatz, auch hinsichtlich seiner Nahrungsökologie an den Menschen anpasst. Dass die Blaumeise, der Grünling und der Haussperling insgesamt in Berlin gut zurechtkommen, selbst in der Innenstadt, indiziert die Beutetierliste des Turmfalken: Der Haussperling stand an erster Stelle, der Grünling an zweiter und die Blaumeise an sechster Stelle der gefangenen Vogelarten. Besonders in einer Metropole wie Berlin besteht weiterer Forschungsbedarf, da die Synurbanisierung verschiedener Vogelarten ständig voranschreitet. / From 2002 to 2004 the feeding ecology of different bird species was studied in Berlin. Thereby consequences like the success in reproduction were also examined. Beside the survey of the breeding bird (2002) and the winter bird community (2002/2003) in five study sites each covering an area of approx. 20 ha along an urban gradient, the species Blue Tit, Greenfinch, House Sparrow and Kestrel were researched in detail. In total, 35 breeding bird species were found in the five sites, which were characterised by different building structure, land use and vegetation cover. Considering the species` number, an urban gradient was clearly visible: In the city centre (Ze) 12 species were recorded, in the industrial area (Ge) 15, in the high-rise apartment building area (Ho) 17, in the detached family housing (Eh) 18 and in the park (Pa) 28 species. During the winter bird census a total of 3,763 individuals and 30 bird species was recorded. In the Pa, the highest reproduction success of the Blue Tit (5,9 fledglings/brood) was recorded. On the basis of the nestlings'' condition and the reproduction success, as well as by documentation of the feeding behaviour of the adult birds by means of video recording (camcorder), it became clear, that food supply was best in the Pa for the Tits. From 2002 to 2004, the carnivorous Kestrel was examined independent from the five study sites at ten nesting sites (nest boxes), which were located in three different zones: City (Ci), Mixed Zone (Mi) and Outskirts (LZ). Striking were anthropogenic food items, like cutlet bones, found in every nest box in the Ci in all three years, which shows the adaptation to humans not only with regard to nesting sites (buildings) but also with regard to feeding ecology. The prey species list of the Kestrel indicates that Blue Tit, Greenfinch and House Sparrow get along well all in all, also in the city centre: the House Sparrow ranked first, the Greenfinch second and the Blue Tit sixth of the captured bird species. Especially in a metropolis like Berlin there is need for further research, because the synurbization of different bird species progresses permanently.

Made available in DSpace on 2014-12-17T15:41:57Z (GMT). No. of bitstreams: 1 RobertaPMM_DISSERT.pdf: 3172444 bytes, checksum: 159d519d0473cdce848696ecb3f8e8f6 (MD5) Previous issue date: 2011-02-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Hybrid systems formed from polymers and transition metals have now their physical and chemical properties extensively investigated for use in electronic devices. In this work, Titanium Dioxide (TiO2) from the precursor of titanium tetrabutoxide and the composite system Poly(Ethylene Glycol)-Titanium Dioxide (TiO2-PEG) were synthesized by sol-gel method. The PEG as acquired and TiO2 and composites powders were analyzed by X-Ray Diffraction (XRD), Spectroscopy in the Infrared region with Fourier transform (IRFT), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS). In the XRD analysis were observed in the TiO2 crystal faces of one of its polymorphs - anatase phase, crystal planes in Poly (Ethylene Glycol) with considerable intensity and in the composite systems the mixture of crystal faces of their precursors isolated and reduction of crystallinity. The TG / DTG suggested increasing the thermal instability of PEG in the composite powders as TiO2 is incorporated into the system. Spectral analysis presented in the infrared overlapping bands for the polymer and metal oxide, reducing the intensity of symmetric stretching of ligand groups in the main chain polymer and angular deformations; were observed using SEM micrographs of the morphological changes suffered by composite systems with the variation of the oxide concentration. Analyses by impedance spectroscopy indicated that the increased conductivity in composite occurs in line with the addition of the metal oxide concentration in the composite system / Sistemas h?bridos formados a partir de pol?meros e metais de transi??o atualmente t?m suas propriedades f?sicas e qu?micas extensivamente investigadas para aplica??o em dispositivos eletr?nicos. Neste trabalho, o Di?xido de Tit?nio (TiO2) a partir do precursor Tetrabut?xido de Tit?nio e o sistema comp?sito Poli (Etileno Glicol)-Di?xido de Tit?nio (PEG-TiO2) foram sintetizados pelo m?todo sol-gel. O PEG como adquirido e os p?s de TiO2 e comp?sitos obtidos foram analisados por Difra??o de Raios X (DRX), Espectroscopia de Absor??o na regi?o do Infravermelho com Transformada de Fourier (EIV-TF), An?lise Termogravim?trica (TG), Microscopia Eletr?nica de Varredura (MEV) e Espectroscopia de Imped?ncia Eletroqu?mica (EIE). Nas an?lises por DRX foram observadas no TiO2, faces cristalinas de um de seus polimorfos fase anat?sio, planos cristalinos no PEG com intensidade substancial e nos sistemas comp?sitos a mistura de faces cristalinas dos seus precursores na forma isolada, bem como, redu??o da cristalinidade. As curvas TG/DTG sugeriram o aumento da instabilidade t?rmica do PEG nos p?s comp?sitos ? medida que TiO2 ? incorporado ao sistema. A an?lise espectral na regi?o do infravermelho apresentou sobreposi??o de bandas relativas ao pol?mero e ao ?xido met?lico, redu??o da intensidade de estiramentos sim?tricos dos grupos ligantes da cadeia principal polim?rica e deforma??es angulares; foram observadas atrav?s das micrografias de MEV modifica??es morfol?gicas sofridas pelos sistemas comp?sitos com a varia??o da concentra??o do ?xido. As an?lises por imped?ncia eletroqu?mica indicaram que o aumento da condutividade nos comp?sitos ocorre em conson?ncia com a adi??o da concentra??o do ?xido met?lico no sistema comp?sito

The present paper aims to show that the oligopoly problem is much more determined than commonly believed. In oligopoly prerequisites are likely to prevail inducing a 'normal' behaviour in accordance with profit maximization. This leads to a price combination located at an exactly definable line section. Finally some consequences upon economic policy are outlined. / Dieser Beitrag versucht zu zeigen, daß das Oligopolproblem wesentlich determinierter ist als gemeinhin angenommen. Im Oligopol liegen die Voraussetzungen besonders günstig, daß durch ein aus dem Streben nach Gewinnmaximierung abgeleitetes, "normales" Verhalten eine Preiskombination auf einem exakt abgrenzbaren Kurvenabschnitt zustande kommt. Abschließend werden wirtschaftspolitische Konsequenzen angedeutet.

Made available in DSpace on 2014-12-17T14:58:24Z (GMT). No. of bitstreams: 1 ArlindoBNN_DISSERT.pdf: 2586996 bytes, checksum: 478bf85288aae614a5921757e3272558 (MD5) Previous issue date: 2014-02-07 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Research for better performance materials in biomedical applications are constants. Thus recent studies aimed at the development of new techniques for modification of surfaces. The low pressure plasma has been highlighted for its versatility and for being environmentally friendly, achieving good results in the modification of physic chemical properties of materials. However, it is requires an expensive vacuum system and cannot able to generate superficial changes in specific regions. Furthermore, it is limits their use in polymeric materials and sensitive terms due to high process temperatures. Therefore, new techniques capable of generating cold plasma at atmospheric pressure (APPJ) were created. In order to perform surface treatments on biomaterials in specific regions was built a prototype capable of generating a cold plasma jet. The prototype plasma generator consists of a high voltage source, a support arm, sample port and a nozzle through which the ionized argon. The device was formed to a dielectric tube and two electrodes. This work was varied some parameters such as position between electrodes, voltage and electrical frequency to verify the behavior of glow discharges. The disc of titanium was polished and there was a surface modification. The power consumed, length, intensity and surface modifications of titanium were analyzed. The energy consumed during the discharges was observed by the Lissajous figure method. To check the length of the jets was realized with Image Pro Plus software. The modifications of the titanium surfaces were observed by optical microscopy (OM ) and atomic force microscopy (AFM ). The study showed that variations of the parameters such as voltage, frequency and geometric position between the electrodes influence the formation of the plasma jet. It was concluded that the plasma jet near room temperature and atmospheric pressure was able to cause modifications in titanium surface / Pesquisas na busca por materiais com melhor desempenho para aplica??es biom?dicas s?o constantes. Assim, estudos recentes buscam o desenvolvimento de novas t?cnicas para modifica??es de superf?cies. O plasma a baixa press?o vem se destacando pela sua versatilidade e por ser ambientalmente correto, obtendo-se bons resultados na modifica??o das propriedades f?sico-qu?micas dos materiais. Por?m, esta t?cnica necessita de um sistema de v?cuo de alto custo e n?o ? capaz de gerar modifica??es superficiais em regi?es pontuais. Al?m disso, limita seu uso em materiais polim?ricos e termosens?veis, devido ?s altas temperaturas do processo. Diante disso, foram criadas novas t?cnicas capazes de gerar um plasma frio a press?o atmosf?rica (APPJ). Com o objetivo de realizar tratamentos superficiais em biomateriais em regi?es pontuais, foi constru?do um prot?tipo capaz de gerar um jato de plasma frio. O prot?tipo gerador de plasma consiste em uma fonte de alta tens?o, um bra?o suporte, um porta amostra e uma ponteira por onde passa o arg?nio ionizado. Dentro desta ponteira existe um tubo diel?trico e dois eletrodos. Neste estudo foram variados alguns par?metros como: posi??o entre eletrodos, tens?o e frequ?ncia el?trica para verificar o comportamento das descargas luminescentes. Tratou-se disco de tit?nio grau II polido e verificou-se a energia el?trica consumida, comprimento, intensidade e modifica??es superficiais do tit?nio. A energia consumida durante as descargas foram verificadas pelo m?todo da figura de Lissajous. Para verificar o comprimento dos jatos foi utilizado o software Image Pro Plus. As modifica??es na superf?cie do tit?nio foram verificadas por microscopia ?tica (MO) e de for?a at?mica (MFA). O trabalho mostrou que varia??es dos par?metros de tens?o, frequ?ncia e posi??o geom?trica entre os eletrodos influenciam na forma??o do jato de plasma. Foi poss?vel concluirque o jato de plasma pr?ximo ? temperatura ambiente e a press?o atmosf?rica foi capaz de provocar modifica??es superficiais no tit?nio

Abstract Animals need information about local conditions to make optimal fitness-enhancing decisions such as where to breed. Information can be acquired by personal sampling of the environment, but it can also be acquired from other individuals. The latter is termed social information use. Social information use has gained a lot of attention in modern ecology because it affects principal ecological phenomena such as animal distribution and resource use. Social information use is not restricted to obviously cognitive mammals and birds but is also found in e.g. reptiles, fish and insects. Social information use studies have thus far been concentrated on situations with one social information user and one (often the same) source species. The community-wide consequences of social information use have almost exclusively been considered in theoretical studies. In this thesis, I studied empirically social information use in the nest site selection within and between species in a cavity-nesting bird community consisting of the collared flycatcher (Ficedula albicollis), the great tit (Parus major) and the blue tit (P. caeruleus). I studied social information use on two time scales: social information gathered just before a breeding attempt, and social information gathered already during the previous breeding season for the following year’s breeding attempt. I used experiments in which different white geometric symbols represented nest site choices of earlier settled tutors and empty nest boxes, and I observed the symbol choices of later-breeding individuals. The symbol approach eradicates bias from innate and learned preferences enabling strong inference. My results demonstrate that collared flycatchers use social information from both con- and heterospecific tutors in different situations in a flexible manner. Hence, social information use seems to be context-dependent. Furthermore, I show that great tits avoid choosing nest site characteristics which were associated with either con- or heterospecifics nests the previous year and prefer symbols which depicted an empty nest box the previous year, probably to avoid nest ectoparasites. I also show that in great tits the male has greater influence on nest site selection than previously assumed even though the female builds the nest. My thesis deepens our understanding about the complexity of social information use and highlights its significance in future ecological research. / Tiivistelmä Eläimet tarvitsevat informaatiota paikallisista olosuhteista tehdäkseen edullisia päätöksiä esimerkiksi siitä, missä lisääntyä. Informaatiota voidaan hankkia tutkimalla ympäristöä itse, mutta sitä voidaan hankkia myös muilta yksilöiltä. Jälkimmäistä kutsutaan sosiaaliseksi informaatioksi. Eläinten sosiaalisen informaation käyttö on saavuttanut viime aikoina paljon huomiota ekologisessa tutkimuksessa, koska se vaikuttaa tärkeisiin ekologisiin ilmiöihin, kuten eläinten levinneisyyteen ja resurssien käyttöön. Sosiaalinen informaation käyttö ei rajoitu vain nisäkkäisiin ja lintuihin, vaan sitä on havaittu myös esimerkiksi matelijoilla, kaloilla ja hyönteisillä. Sosiaalisen informaation käyttöä on tutkittu lähes yksinomaan lajien sisällä tai käyttäen ainoastaan yhtä sosiaalisen informaation lähdelajia. Yhteisötason vaikutuksia on pohdittu miltei pelkästään teoreettisissa tutkimuksissa. Tässä väitöskirjatyössä tutkin kokeellisesti sosiaalisen informaation käyttöä pesäpaikan valinnassa lajin sisällä ja lajien välillä kolopesivien lintujen yhteisössä sepelsiepolla (Ficedula albicollis), talitiaisella (Parus major) ja sinitiaisella (P. caeruleus). Otin tutkimuksissani huomioon kaksi aikatasoa: tutkin juuri ennen pesimisyritystä kerätyn sekä jo edellisen lisääntymiskauden aikana seuraavan vuoden pesintää varten hankitun sosiaalisen informaation käyttöä. Kokeissani käytin linnunpönttöihin kiinnitettyjä erilaisia valkoisia geometrisia symboleita, jotka edustivat aiemmin pesinnän aloittaneiden lintujen eli tuutoreiden pesäpaikanvalintoja. Seurasin tämän jälkeen myöhemmin pesimään saapuvien parien symbolivalintoja. Tulosteni perusteella sepelsiepot hankkivat sosiaalista informaatiota sekä lajitovereiltaan että tiaisilta joustavasti eri tilanteissa. Lisäksi osoitan, että talitiaiset välttävät valitsemasta pesäpaikkoja, jotka olivat asuttuina edellisenä vuonna, ja suosivat sellaisia pesäpaikkoja, joissa ei pesitty edellisenä vuonna - todennäköisesti välttääkseen kirppuja ja muita pesäloisia. Osoitan myös, että talitiaiskoirailla on suurempi vaikutus pesäpaikan valintaan kuin aikaisemmin on oletettu, vaikka naaraat rakentavat pesän. Väitöskirjatyöni syventää käsitystämme sosiaalisen informaation käytön monitahoisuudesta eläinkunnassa ja korostaa sen merkitystä ekologisessa tutkimuksessa.

En partant du cadre conceptuel des modèles IDRC (Interprétation-Décisions-Ressources- Contraintes) et du modèle d'Efforts de l'interprétation simultanée de Daniel Gile entre langues vocales, nous tenterons d'analyser le processus de l'interprétation en langue des signes et étudierons la charge cognitive inhérente au passage d'une langue vocale (canal audio-vocal), à une langue signée (canal visuo-gestuel). Nous analyserons en premier lieu l’ensemble des contraintes concourant à l’exercice de l’interprétation en langue des signes pouvant se distinguer de celles généralement observées en interprétation entre langues vocales (nous incluons les langues vocales syntaxiquement très éloignées) telles que les contraintes socio-économiques, les contraintes linguistiques et enfin les contraintes d’espace. Nous procéderons ensuite à une analyse cognitive du processus de l’interprétation en nous référant au modèle d'Efforts de l’interprétation simultanée de Gile (Effort d'Écoute et d'Analyse, Effort de Mémorisation à court terme, Effort de Production, Effort de Coordination de ces trois activités simultanées), et nous chercherons à envisager sa transposition aux langues des signes. Pour mieux comprendre les mécanismes constitutifs du processus, nous observerons particulièrement le concept de scénarisation (Séro-Guillaume, 2008) pour une première analyse de la charge cognitive de l’interprète en action. Cette capacité de représentation synthétique visuelle est-elle plus ou moins grande si on prend en compte le degré d'abstraction du discours, la technicité de l'énoncé, le manque de correspondances lexicales, le contexte de l'interprétation (pédagogique, conférence, etc.), la préparation ? Notre analyse du processus se base sur un corpus constitué de plusieurs études empiriques d’interprétations vers la langue des signes : une étude semi-expérimentale, une étude de cas naturaliste et une étude expérimentale, ainsi que sur des interviews d’interprètes et un focus group. Les observations faites sur l’ensemble de ces études nous ont permis de croiser nos données et de dégager les éléments pertinents de nos résultats pour une avancée dans la compréhension du processus cognitif de l’interprétation en langue des signes. / Taking as its point of departure the conceptual framework provided by the IDRC models (Interpreting-Decisions-Resources-Constraints) and Daniel Gile’s Effort model of simultaneous interpreting between spoken languages, this thesis aims to analyse the process of sign language interpreting and study the cognitive load inherent in encoding information from a spoken language (an auditory-vocal modality of language production) into signed language (a vision and gesture-based modality). The first part of the work analyses the set of constraints involved in the exercise of sign language interpreting, as distinguished from those generally observed to apply between spoken languages (including languages syntactically far apart), such as socio-economic constraints, linguistic constraints and, finally, spatial constraints. There follows a cognitive analysis of the interpreting process with reference to Gile’s Effort model of simultaneous interpreting (Listening and Analysis Effort, Memory Effort, Production Effort, Effort of Coordination of these three simultaneous activities), with an attempt to envisage transposing its application to sign language. In order to gain better understanding of the constituent mechanisms of the process, initial analysis of the cognitive load of the interpreter in action accords particular attention to the concept of scénarisation (scene-staging) (Séro-Guillaume, 2008). Is this capacity for creating a visual picture from sequential meaning greater or lesser when factors such as the degree of abstraction of the speech, the technicality of its content, a lack of lexical correspondence, the interpreting context (educational setting, conference setting, etc), and the amount of preparation are taken into account? Analysis of the process is based upon a corpus comprising several empirical studies of interpreting into sign language: a semi-experimental study, a naturalistic case study, and an experimental study, as well as on interpreter interviews and a focus group. The observations drawn from all of these studies have enabled cross-referencing of our data and the identification of the relevant elements of our research results in order to advance understanding of the cognitive process of sign language interpreting.

The present paper aims to show that the oligopoly problem is much more determined than commonly believed. In oligopoly prerequisites are likely to prevail inducing a 'normal' behaviour in accordance with profit maximization. This leads to a price combination located at an exactly definable line section. Finally some consequences upon economic policy are outlined. / Dieser Beitrag versucht zu zeigen, daß das Oligopolproblem wesentlich determinierter ist als gemeinhin angenommen. Im Oligopol liegen die Voraussetzungen besonders günstig, daß durch ein aus dem Streben nach Gewinnmaximierung abgeleitetes, "normales" Verhalten eine Preiskombination auf einem exakt abgrenzbaren Kurvenabschnitt zustande kommt. Abschließend werden wirtschaftspolitische Konsequenzen angedeutet.

v III. Abstract (EN) According to the Disposable soma theory, senescence is mainly influenced by adaptive allocation of resources among the physical growth, reproduction and self-maintaining processes, which depend on expected survival of an individual. The amount of allocated resources may be influenced by external environmental factors such as heavy metal pollution or by inner factor e.g. reproduction. The aim of my diploma thesis was to clarify the relationships between senescence, selected haematological traits, reproduction and efficiency of innate immunity mechanism. Moreover, we are interested in the role of heavy metal pollution in ageing and haematology. The heterophiles to lymphocytes ratio (H/L) was used as a marker of long-term stress caused by these physiological expenses. This study summarizes partial data collected within the long-term research of great tits (Parus major) in Prague, Czech Republic, I participated in. We have more than 300 samples of repeatedly captured individuals at our disposal. The structure of this unique dataset allows us to observe changes in the traits of our interest during an avian lifespan. Our results show that during aging, males experience a noticeable increase in the H/L ratio compared to females. Although we have not found the effect of age on the brood size,...

Made available in DSpace on 2014-12-17T15:42:01Z (GMT). No. of bitstreams: 1 EdissonMJ.pdf: 6565731 bytes, checksum: 5d6fdd6db6fc25a30c6100d96fff1edc (MD5) Previous issue date: 2007-08-24 / TiTanate NanoTubes (TTNT) were synthesized by hydrothermal alkali treatment of TiO2 anatase followed by repeated washings with distinct degrees of proton exchange. TTNT samples with different sodium contents were characterized, as synthesized and after heattreatment (200-800?C), by X-ray diffraction, scanning and transmission electron microscopy, electron diffraction, thermal analysis, nitrogen adsorption and spectroscopic techniques like FTIR and UV-Vis diffuse reflectance. It was demonstrated that TTNTs consist of trititanate structure with general formula NaxH2−xTi3O7?nH2O, retaining interlayer water in its multiwalled structure. The removal of sodium reduces the amount of water and contracts the interlayer space leading, combined with other factors, to increased specific surface area and mesopore volume. TTNTs are mesoporous materials with two main contributions: pores smaller than 10 nm due to the inner volume of nanotubes and larger pores within 5-60 nm attributed to the interparticles space. Chemical composition and crystal structure of TTNTs do not depend on the average crystal size of the precursor TiO2-anatase, but this parameter affects significantly the morphology and textural properties of the nanostructured product. Such dependence has been rationalized using a dissolution-recrystallization mechanism, which takes into account the dissolution rate of the starting anatase and its influence on the relative rates of growth and curving of intermediate nanosheets. The thermal stability of TTNT is defined by the sodium content and in a lower extent by the crystallinity of the starting anatase. It has been demonstrated that after losing interlayer water within the range 100-200?C, TTNT transforms, at least partially, into an intermediate hexatitanate NaxH2−xTi6O13 still retaining the nanotubular morphology. Further thermal transformation of the nanostructured tri- and hexatitanates occurs at higher or lower temperature and follows different routes depending on the sodium content in the structure. At high sodium load (water washed samples) they sinter and grow towards bigger crystals of Na2Ti3O7 and Na2Ti6O13 in the form of rods and ribbons. In contrast, protonated TTNTs evolve to nanotubes of TiO2(B), which easily convert to anatase nanorods above 400?C. Besides hydroxyls and Lewis acidity typical of titanium oxides, TTNTs show a small contribution of protonic acidity capable of coordinating with pyridine at 150?C, which is lost after calcination and conversion into anatase. The isoeletric point of TTNTs was measured within the range 2.5-4.0, indicating behavior of a weak acid. Despite displaying semiconductor characteristics exhibiting typical absorption in the UV-Vis spectrum with estimated bandgap energy slightly higher than that of its TiO2 precursor, TTNTs showed very low performance in the photocatalytic degradation of cationic and anionic dyes. It was concluded that the basic reason resides in its layered titanate structure, which in comparison with the TiO2 form would be more prone to the so undesired electron-hole pair recombination, thus inhibiting the photooxidation reactions. After calcination of the protonated TTNT into anatase nanorods, the photocatalytic activity improved but not to the same level as that exhibited by its precursor anatase / Titanatos nanoestruturados, particularmente TiTanatos NanoTubulares (TTNT), foram sintetizados por tratamento hidrot?rmico alcalino de TiO2-anat?sio seguido de repetidas lavagens com diversos graus de troca prot?nica. Amostras de TTNT com diferentes teores de s?dio foram caracterizadas na forma de p? seco e ap?s calcina??o (200-800?C) por difra??o de raios-X, microscopia eletr?nica de varredura e transmiss?o, difra??o de el?trons, an?lise t?rmica, adsor??o de nitrog?nio e t?cnicas espectrosc?picas de infravermelho e de reflet?ncia difusa no UV-Vis?vel. Demonstrou-se que tais materiais de paredes multilamelares s?o trititanatos de f?rmula geral NaxH2−xTi3O7?nH2O, retendo ?gua entre as lamelas. A remo??o de s?dio da estrutura reduz a quantidade de ?gua contraindo o espa?o interlamelar levando, combinado a outros fatores, ao aumento da ?rea e do volume de poros espec?ficos. Os TTNTs s?o materiais mesoporosos com duas contribui??es principais: poros menores que 10 nm devido ao volume interno dos nanotubos e poros entre 5 e 60 nm devido aos espa?os interpart?cula. A composi??o qu?mica e a estrutura cristalina do TTNT n?o dependem do tamanho de cristalito do TiO2-anat?sio precursor, todavia este par?metro afeta significativamente a morfologia e as caracter?sticas texturais do produto nanoestruturado. Tal depend?ncia foi racionalizada atrav?s de um mecanismo de dissolu??o-recristaliza??o que leva em conta a velocidade de dissolu??o do TiO2 de partida e sua influ?ncia sobre a taxa de crescimento de nanofolhas intermedi?rias em rela??o ? taxa de seu curvamento a nanotubos. A estabilidade t?rmica do TTNT ? definida pelo teor de s?dio e em pequena extens?o pelo tipo de anat?sio de partida. Foi demonstrado que o TTNT ap?s perder a ?gua intercalada entre 100 e 200?C se transforma pelo menos parcialmente num hexatitanato NaxH2−xTi6O13 intermedi?rio ainda nanotubular. A transforma??o t?rmica do tri- e hexatitanato nanoestruturados ocorre em maior ou menor temperatura e segue diferentes rotas dependendo do teor de s?dio. No caso de alto s?dio sinterizam e crescem at? grandes cristais de Na2Ti3O7 e Na2Ti6O13 na forma de bast?es e fitas acima de 600?C. No caso da amostra protonizada evoluem para nanotubos de TiO2(B) que facilmente se convertem em nanobast?es de anat?sio acima de 400?C. Al?m de hidroxilas e acidez de Lewis t?picos dos ?xidos de tit?nio, os TTNTs apresentam uma pequena contribui??o de acidez prot?nica capaz de se coordenar com a piridina a 150?C, e que ? perdida ap?s sua calcina??o e transforma??o ? anat?sio. O ponto isoel?trico do TTNT variou dentro da faixa 2,5- 4,0, indicando o comportamento de um ?cido fraco. Apesar de se revelar um semicondutor exibindo banda de absor??o t?pica no espectro de UV-vis?vel com energia de bandgap ligeiramente superior ao do respectivo TiO2-anat?sio precursor, os TTNTs apresentaram baixo desempenho fotocatal?tico na degrada??o de corantes cati?nico e ani?nico. Concluiu-se que a causa fundamental reside em sua estrutura de titanato lamelar que, em rela??o ? forma TiO2, apresentaria maior probabilidade de recombina??o do par el?tron-lacuna (e-/h+), inibindo as rea??es de fotoxida??o. A transforma??o do TTNT prot?nico ? nanobast?es de anat?sio melhorou a atividade fotocatal?tica, por?m ainda sem atingir o mesmo desempenho do TiO2-anat?sio precursor

Made available in DSpace on 2014-12-17T15:42:01Z (GMT). No. of bitstreams: 1 IedaNSM.pdf: 5948604 bytes, checksum: dbf245a349dd04cff535e8ba2e89601d (MD5) Previous issue date: 2007-07-06 / The aim of this work was to study a series of 11 different compositions of Ti-Zr binary alloys resistance to aggressive environment, i. e., their ability to keep their surface properties and mass when exposed to them as a way to evaluate their performance as biomaterials. The first stage was devoted to the fabrication of tablets from these alloys by Plasma-Skull casting method using a Discovery Plasma machine from EDG Equipamentos, Brazil. In a second stage, the chemical composition of each produced tablet was verified. In a third stage, the specimen were submitted to: as-cast microstructure analysis via optical and scanning electron microscopy (OM and SEM), x-ray dispersive system (EDS) chemical analysis via SEM, Vickers hardness tests for mechanical evaluation and corrosion resistence tests in a 0.9% NaCl solution to simulate exposition to human saliva monitored by open circuit potential and polarization curves. From the obtained results, it was possible to infer that specimens A1 (94,07 wt% Ti and 5,93% wt% Zr), A4 (77,81 wt % Ti and 22,19 wt % Zr) and A8 (27,83 wt% Ti and 72,17 wt% Zr), presented best performance regarding to corrosion resistance, homogeneity and hardness which are necessary issues for biomaterials to be applied as orthopedic and odontological prosthesis / Este trabalho teve como finalidade estudar uma s?rie de onze ligas met?licas bin?rias, tit?nio zirc?nio, quanto ? capacidade de resistirem ?s deteriora??es sem sofrerem modifica??es de suas propriedades iniciais de massa e superf?cie quando expostas a meios agressivos, como condi??o fundamental para que as mesmas sejam aplicadas como biomateriais. A primeira etapa tratou da confec??o das amostras das ligas em forma de pastilhas, empregando-se o processo de fundi??o Plasma Skull realizado na m?quina Discovery Plasma, produzida no Brasil pela EDG Equipamentos. Na segunda etapa, as amostras confeccionadas foram submetidas aos ensaios para a determina??o da composi??o qu?mica resultante de cada liga da s?rie ap?s a fus?o. E durante a terceira etapa foram feitos os procedimentos de avalia??es das amostras quanto ? homogeneidade e apresenta??o da microestrutura de cada uma das ligas no estado bruto de fus?o, como resultados dos ensaios metalogr?ficos por microscopia ?ptica e microscopia eletr?nica de varredura acoplada a espectroscopia por energia dispersiva de raios-x; quanto ? propriedade mec?nica de dureza medida em escala Vickers (HV); e quanto ?s propriedades qu?micas de resist?ncia ? corros?o, quando expostas em solu??o de cloreto de s?dio 0,9 %, para simular a saliva, empregando-se o monitoramento do potencial de circuito aberto e as curvas de polariza??o. A partir dos resultados obtidos foi poss?vel identificar as pastilhas de composi??es qu?micas A1 (94,07% de Ti e 5,93% de Zr), A4 (77,81% de Ti e 22,19% de Zr) e A8 (27,83% de Ti e 72,17% de Zr) que resultaram como maiores detentoras do conjunto de propriedades de resist?ncia ? corros?o, homogeneidade e dureza, as quais s?o mais necess?rias em biomateriais tipo pr?teses ortop?dicas ou odontol?gicas