A utilização de silanos como agentes promovedores de adesão demonstrou ser uma solução útil para a união entre materiais dissimilares, incrementando a adesão e aumentando inclusive a resistência a corrosão entre os mesmos . A utilização destes agentes como promovedores de adesão, sobre diferentes combinações de materiais, continua sendo estudada atualmente. Este trabalho teve como objetivo avaliar a capacidade de diferentes tipos de silanos como agentes promovedores de adesão. tanto funcionais como não funcionais, na união entre aço SAE 1060 e resina epóxi. Para isto, foram primeiramente obtidos filmes de silano sobre amostras de aço através de diferentes tratamentos. Estes filmes obtidos foram caracterizados por meio de diferentes técnicas. Foram realizados testes de aderência através do método especificado pela norma ASTM D3359 para avaliar a resistência de adesão dos diferentes filmes ao substrato. As amostras testadas foram analisadas através de microscopia eletrônica de varredura (MEV). Também, foram realizadas análises de espectroscopia de energia dispersiva (EDS) sobre as mesmas amostras, permitindo obter outras características dos filmes de silano formados. Os tratamentos que apresentaram melhores resultados na caracterização em MEV/EDS foram escolhidas para a preparação dos corpos de prova de uniões com resina epóxi. Estas uniões foram utilizadas para realizar testes de adesão do tipo arrancamento de modo a avaliar o efeito dos tratamentos com silano na resistência de adesão da união entre o substrato de aço e a resina epóxi. Os resultados dos testes de arrancamento permitem afirmar que existe uma melhoria na resistência de adesão com um dos tratamentos com silano sobre o substrato de aço seguido de revestimento com resina epóxi. A utilização de tratamentos com silanos mostram-se promissoras para esta aplicação. / The use of silanes as adhesion enhancer agent proved to be a useful solution for the union of dissimilar materials, increasing the bond strength between them, also increase the corrosion resistance. The use of these agents as adhesion enhancer, with different materials combination, is still being studied today. The aim of this work was to evaluate the ability of different silanes as adhesion agent promoters in joints of SAE 1060 steel and epoxy resin; both functional and not functional silanes. At the beginning and for this purpose were different types of treatments used to obtain silane films on steel samples. Different techniques were used to characterize these films. To evaluate the bond strength adhesion test where performed according to the ASTM D3359 standard. Samples were analyzed with scanning electron microscope (SEM). Energy-dispersive spectroscopy (EDX) analyses were also performed on the same sample allowing to obtain others characteristics of the silane films formed. The treatments that have shown a better performance in the SEM/EDX analyses were selected to make steel and epoxy resins joint samples. These specimens were used to perform pull-out type adhesion test to evaluate the effect of the silanes treatments in the bond strength of steel and epoxy resin joints. The results of de pull-out test indicate that the use of silane improves the bond strength of steel and epoxy resin joints. The use of silane treatments has shown promising results for this application.

Made available in DSpace on 2014-06-12T18:02:03Z (GMT). No. of bitstreams: 2 arquivo2369_1.pdf: 4588742 bytes, checksum: 7359c39184a61c299104b1a396348c30 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Pela simplicidade do tratamento teórico, fácil processabilidade, e possíveis aplicações em ciências dos materiais, oligômeros conjugados representam uma classe especial de compostos orgânicos. A substituição terminal dessas estruturas com grupos doadores (D) e aceitadores de elétrons (A) resulta em moléculas (D 􀀀 􀀀 A) com propriedades óticas e eletrônicas excepcionais. Em geral, estes sistemas são caracterizados por uma efetiva Transferência de Elétrons Intramolecular Fotoinduzida (TEIF). Por exemplo, betaínas são compostos D 􀀀􀀀 A que têm recebido uma atenção especial devido à grande redução do seu momento de dipolo após excitação eletrônica, o que induz uma intensa transferência de carga do grupo D para o A. Em particular, examinamos betaínas piridínicas, contendo uma longa ponte -conjugada, devido à sugestão de que podem exibir uma TEIF na direção inversa, isto é, do grupo A para o D, como consequência de uma mudança observada na localização dos orbitais moleculares de fronteira (OMFs) HOMO e LUMO. Inicialmente, confirmamos por método ab initio a existência de uma TEIF inversa em uma família representativa de betaínas piridínicas, e destacamos o papel fundamental desempenhado pela ponte conjugada. Estes resultados contribuem para a expectativa de que a TEIF inversa seja um efeito físico real e não um artefato do método utilizado. Estendemos nossa análise a um total de 88 oligômeros D􀀀()n 􀀀A pertencentes a 8 novas famílias distintas de moléculas, nas quais a inversão HOMO-LUMOfoi identificada. Verificamos ainda que os orbitais HOMO-i e LUMO+i (i=1,2 e 3) desses cromóforos também são suscetíveis a mudanças na localização espacial como função do tamanho da cadeia conjugada, devido a sucessivos pontos de cruzamento entre os níveis de energia destes orbitais. Em seguida, exploramos teoricamente os efeitos da mudança na localização espacial dos OMFs sobre as propriedades espectroscópicas das 88 estruturas examinadas. Por m, investigamos a influência do solvente sobre as propriedades eletrônicas e espectroscópicas de uma família de moléculas D 􀀀 ()n 􀀀 A derivados da Betaína-30 utilizando modelos de solvatação contínuos. Concluímos que a intensidade e a direção dos deslocamentos solvatocrômicos do espectro destes cromóforos dependem do comprimento da cadeia conjugada que conecta os grupos D e A, sugerindo uma possível forma de verificação experimental para o fenômeno de inversão HOMO-LUMO. Discutimos também, as possíveis aplicações deste efeito para o desenvolvimento de uma nova classe de dispositivos da Eletrônica Molecular em fase líquida.

[pt] A utilização de pneus usados é uma técnica interessante para reforço de solos, sob o aspecto ambiental. Os pneus usados constituem uma matéria-prima abundante e de custo reduzido. A técnica de utilização de pneus em obras geotécnicas vem sendo difundida no Brasil desde meados dos anos 90, com a construção do muro experimental de solopneus da PUC-Rio, em colaboração com a Fundação Geo-Rio e a Universidade de Ottawa (Canadá). O presente trabalho tem por objetivo apresentar a metodologia para avaliação da resistência ao arrancamento de malhas de pneus. Os pneus podem ser dispostos em um plano horizontal e amarrados entre si, formando uma malha de reforço. Podem ser utilizados pneus inteiros ou com uma das bandas laterais cortadas. A sobrecarga atuando no reforço provém do confinamento provocado pela altura do aterro de solo, construído sobre a malha de pneus. Os ensaios de arrancamento dos pneus no campo utilizaram uma estrutura metálica de reação, atirantada, a qual foi desenvolvida especificamente para o programa experimental sobre reforço de solos. Os resultados permitiram idealizar um mecanismo de ruptura envolvido no processo de arrancamento das malhas de pneus, bem como a verificação das características de resistência e deformabilidade deste tipo de reforço. / [en] The use of scrap tires as soil reinforcement is an environmentally interesting technique. Scrap tires are an abundant and low cost waste material. The technique for using tires in geotechnical construction is becoming popular in Brazil since the construction of an experimental gravity wall made with soil and tires in 1995. This wall was part of a research project by carried out by PUC-Rio in collaboration with Geo-Rio and University of Ottawa. The objective of this work is to present a methodology to evaluate the pull-out behaviour of tire meshes. The tires can be placed in a horizontal plane and tied with rope or wire, forming a reinforcement mesh. The surcharge on these meshes comes from the confinement due to the height of a soil embankment built on the mesh. Field pull-out tests were performed on these reinforcement meshes, using a metallic reaction structure, which was developed specifically for this experimental research. The results allowed the idealization of a shearing mechanism based on the pull-out of tire meshes, as well as the verification of the strength and deformability characteristics of the reinforcement.

Den explosivt ökande mängden information som finns tillgänglig på Internet har även sina avigsidor. Att hitta meningsfull information och kunskap på Internet idag blir allt svårare. Behovet av verktyg som kan hjälpa individer och företag att ta fram värdefull information, speciellt tidskritisk sådan på ett effektivt sätt, är och kommer att bli mycket stort. Likaså kommer behovet av att komma åt denna information, oberoende av tid och plats att vara stort och bli allt större i takt med den ständigt accelererande utvecklingstakten. Vi har försökt att belysa hypotesens komplexitet och visa på det faktum att inte bara en utan många beståndsdelar spelar in vid skapandet av en personanpassad informationsportal. Arbetet har grundat sig på att identifiera de krav som skulle kunna ställas på grundläggande funktioner. Utifrån dessa har vi presenterat förslag på funktioner och konstruktion som kan användas till en applikationslösning. Layout-funktionerna som presenterats i arbetet är ytterst viktiga och ser till att utvald information presenteras på ett samlat och strukturerat sätt. Push-funktionerna är väsentliga för att användaren ska ha kontroll över vilken information som ska skickas ut. De funktioner som ställer in och kontrollerar informationsinnehåll är de som vi har kommit fram till bör anses vara viktigast. Dessa gör att informationen är korrekt, avgränsad och uppdaterad på det sätt användaren önskar. Detta arbete i sig och den applikationslösning som vi har tagit fram, anser vi vara en bra grund för att konstruera framtida personanpassade informationsportaler.

On se propose d’analyser le régime transitoire de décrochage à l’aide de la simulation numériqueinstationnaire de type DNS. Cette approche permet de reproduire avec fidélité l’écoulementdans la région critique de Bulbe de Décollement Laminaire au bord d’attaque, encoreimpossible à modéliser ou mesurer avec précision. Après une étape de validation, la sensibilitédu BDL au niveau de turbulence extérieure est étudiée et comparée favorablement à celleétablie récemment dans la littérature. La phase d’établissement du décollement massif depuisle BDL est reproduite en réalisant de petites variations d’incidence à travers l’angle critiqued’apparition du décrochage. Ce raisonnement ”aux petites perturbations” permet de reproduirel’éclatement du BDL communément rattaché au décrochage statique. La déstabilisation de larégion de BDL est alors étudiée à l’aide d’une base de données instationnaires et moyennes quipermet pour la première fois de rendre compte des déformations 3D du BDL. Conservant ceprotocole, et faisant varier la vitesse du profil, on est en mesure d’évaluer l’influence de cettedernière sur le régime transitoire. Des mouvements de rotation de plus forte amplitude angulaireont permis de mettre en évidence un mécanisme de décrochage sensiblement différent duprécédent. La couche de mélange surplombant le BDL s’enroule alors pour donner naissance àun tourbillon énergétique (Leading Edge Vortex), communément associé au décrochage dynamique.Enfin, l’analyse du champ de vitesse moyen a permis de valider un critère empiriqued’apparition de l’éclatement du BDL, qui s’est révélé pertinent aussi bien pour les mouvementsde faible amplitude que ceux plus amples. / High fidelity numerical simulation is used to study the transitory flow involved during the staIl ofan airfoil at high angle of attack. The nearly DNS resolution in the Laminar Separation Bubbleprovides the required accuracy to reproduce this complex flow that still represents a challenge forboth experimentation and modeling. The numerical procedure is comprehensively validated withparticular attention to the LSB region. The sensitivity of the LSB to an external disturbance ismonitored on the airfoil and is favorably compared with a recent study on flat plate in the literature.The destabilization of the LSB during staIl is reproduced with a small variation of the angle ofattack through the critical angle. The LSB bursting, typical of a static leading edge staIl, is thusreproduced. A comprehensive study of the unsteady events during the transitory flow is performedby means of a high frequency sampling of spanwise and short time averaged data base. Ofparticular interest is the 3D deformation of the flow captured by using a large spanwisecomputational domain (one chord length). The influence of the motion dynamic is then explored.The transitory is significantly affected by a high angular amplitude motion. The shear-Iayer in theLSB undergoes a roll-up which is found to be responsible for the formation of the Leading EdgeVortex, typical of a dynamic staIl configuration. An empirical criterion for the prediction of burstingis then assessed using the statistical data base. Results are found to surprisingly match the incipientof staIl in both static and dynamicaJ conditions.

Studiens syfte var att undersöka unga svenskars anledningar samt erfarenhet av migration från Sverige till Barcelona, Spanien, och såvida de kan tänka sig att permanent bosätta sig utomlands. Forskning inom migration finns det gott om, dock saknas kvalitativa studier som fokuserar på svenska ungdomars motiv till utlandsflytten. Studiens teoretiska ramverk bygger på fyra perspektiv; ”Push-pullteorin” som handlar om olika faktorer som har dragit individen till den nya orten samt ifrån ursprungsorten, ”socialt nätverksteorin” som behandlar frågan om huruvida ens kontaktnätverk kan påverka beslut inför en sådan flytt, ”platsanknytningar” som berättar om hur vi känner inför olika platser och hur pass mycket man känner en anknytning till platsen ifråga sett ur olika dimensioner, samt ”identitet” där jag undersöker om informanternas identitetsbygge kan vara en drivkraft i beslutsprocessen. Studiens data består av 8 informanter som har intervjuats i Barcelona. Samtliga informanter är svenska kvinnor och män mellan 21–28 år. Studien visar att anledningen till deras flytt till Barcelona var att de behövde en ny start i livet. De ville hitta sig själv, utvecklas samt få uppleva något mer, något nytt. De förklarar att de flyttade ifrån Sverige för att få kunna vara vem man vill och göra vad man vill utan en massa normer som begränsar ens handlingsutrymme. Push-faktorer dominerade således i beslutsfattandet. Sociala nätverksteorin verkar ha en stor påverkan på deras flytt då alla har flera vänner som har flyttat utomlands. Nästan alla kunde tänka sig att permanent bosätta sig utomlands och det som då skulle vara den främsta orsaken var om de skulle inleda ett förhållande med någon som bor i utlandet. En annan anledning skulle vara jobbet/karriären.

Recent bioinformatic analyses identified an operon encoding a potential Type I Secretion System (T1SS) in Treponema pallidum that we hypothesize functions to export key treponemal virulence factors that may contribute to the unique invasiveness and pathogenesis of this spirochete. The membrane fusion protein component (MFP) of T1SSs in other organisms has been shown to play a role in substrate recognition. Hence, the objective of this project is to use the putative MFP, Tp0965, of the potential T. pallidum T1SS to investigate protein-protein interactions with the T. pallidum virulence factor pallilysin (Tp0751) and assess the possibility of the latter being a T1SS substrate. Moreover, protein-protein interactions between Tp0965 and a Treponema phagedenis lysate are investigated with the goal of identifying putative T1SS substrates in this spirochete that could result in the discovery of novel T. pallidum virulence factors via amino acid sequence similarity. Plate-based binding studies and pull-down assays showed a low level of interaction between recombinant Tp0965 and the previously characterized host-component-binding protease, pallilysin, suggesting that the export of this virulence factor could occur via the putative T1SS. Additionally, bioinformatic analyses of the related but cultivable model spirochete T. phagedenis predicted the presence of a potential T1SS homologous to the putative T1SS in T. pallidum. Thus, a more global and unbiased pull-down assay using “bait” Tp0965 and a “prey” T. phagedenis lysate was carried out, followed by mass spectrometric analysis to identify putative novel T1SS substrates with potential homologs in T. pallidum. We successfully identified a T. phagedenis protein, TphBIg, that showed evidence of an interaction with Tp0965. TphBIg seems to possess characteristics of a T1SS substrate suggesting it may be secreted via this system in T. phagedenis. Upon bioinformatic analysis, it was found that TphBIg showed weak amino acid sequence similarity as well as some structural similarity to the T. pallidum protein, Tp0854. Tp0854 is predicted to contain a sialidase and a phosphatase domain with an RTX motif, which is characteristic of some T1SS substrates. Thus, it was hypothesized that if Tp0854 had characteristics of a T1SS, it may interact with Tp0965. Therefore, the phosphatase domain containing the RTX motif was produced recombinantly and plate-based binding studies indeed suggested an interaction with Tp0965, confirming the in silico-predicted interaction. Future experiments to characterize the potential T1SS and substrates in T. pallidum could comprise the functional and structural characterization of the novel putative T1SS substrate, Tp0854. This would include assays to investigate the putative sialidase and phosphatase activities of Tp0854, as well as the identification of Tp0854-Tp0965 interacting sites. Moreover, as a more definite test for T1SS substrate secretion, T. pallidum pallilysin and/or Tp0854 could be expressed heterologously in an E. coli strain harbouring an endogenous T1SS and test for secretion. Similarly, the reconstitution of the T. pallidum putative T1SS in liposomes could be used to further investigate the secretion of pallilysin and/or Tp0854 via this system. Additionally, the optimized unbiased pull-down technique could be further applied to detect more protein-protein interactions within T. pallidum and potentially lead to the identification of more virulence factors that may be secreted via the T1SS. These studies constitute the first investigation of a putative T1SS and substrates within T. pallidum. Thus, insight gained will lead to a better understanding of the mechanisms facilitating T. pallidum host invasion and may reveal new potential vaccine targets to prevent bacterial dissemination and chronic infection. / Graduate

Syfte och forskningsfråga: Syftet med studien är att undersöka varför kinesiska studenter väljer att studera på universitetsnivå i Sverige. Med detta syfte i åtanke formulerades följande forskningsfrågor: Vilka faktorer spelar in i kinesiska studenters beslut att studera utomlands? Vilka faktorer spelar in i kinesiska studenters jämförelse av olika studiedestinationer? Hur spelar dessa faktorer in vid beslutet att studera i Sverige? Metod: Metodvalet för denna uppsats är av kvalitativ karaktär och forskningsansatsen är deduktiv. Den empiriska datan bygger på åtta semistrukturerade intervjuer med kinesiska studenter som valt studera i Sverige under minst sex månader. Empiri till uppsatsens förstudie består av tre semistrukturerade samtal med personal från Linnéuniversitetet, som har en relevant koppling till det valda ämnet. Slutsats: Kinesiska studenter påverkas starkt av rekommendationer och råd från alumner med erfarenhet av att studera i Sverige. Studien ger indikationer på att råd och rekommendationer från sociala länkar med egna erfarenheter har en stark inverkan på beslutet vid köp av en högengagemangstjänst i en kultur med en hög grad av Hofstedes kulturella dimensioner: kollektivism och osäkerhetsundvikande. / Purpose and research question: The aim of the thesis is to examine why Chinese students choose Sweden as a destination for studies abroad. With the above stated purpose in mind, the research questions are as follow: What factors influence Chinese students’ decision- making of studying abroad? What factors influence Chinese students comparison between different study destinations? How do these factors affect the decision to study in Sweden? Method: The study is based in a qualitative research method. The empirical data is collected through a pilot study with three semi-structured interviews with staff from Linnaeus University and a study with eight semi- structured interviews with Chinese students that currently are studying in Sweden or have studied in Sweden. Conclusion: Chinese students are highly affected by recommendations from alumni with experience from studying in Sweden. The result of the study indicate the importance of advice and recommendations from social links with similar experiences in the decision making when buying a high-involvement service in a culuture with a high degree of Hofstedeés cultural dimensions: collectivism and uncertainty avoidance.

Magister Public Health - MPH / This secondary data study, framed in social constructionism theory, descibes and analyses the "pull" factors influencing migration of health professionals developing to developed countries. The literature review sets the context withing which international migration takes place and explores relevant aspects of the G8, globalisation, and the General Agreement on Trade in Services. The research demonstrates that temporary or permanent international migration occurs for employment or study purposes. It further confirms that, despite the lack of accurate data from African counties, the number of health professionals leaving the continent has increased significantly during the 1990's. / South Africa

Women increasingly 'make the leap' into 'traditionally male' entrepreneurial ventures. This dissertation reviews relevant literature on what, how many, why and where women entrepreneurs in construction found their niche markets, which aspects make women unique, how poverty and unemployment hurt women and what entrepreneurial barriers women experience, comparing a developed (USA) and developing country (SA). A survey instrument was developed to test the constructs empirically and case studies illustrate the models of success. Given the excellent results of the Cronbach Alpha and Factor Analysis, the instrument developed proved to be reliable and valid and could be used for similar studies. The case- and empirical studies analyse women ownership attitudes and push and pull factors to determine why women became entrepreneurs in construction. The main findings are: 1. Women took up their rightful place as construction entrepreneurs. It is a myth that they are only labourers. 2. Differences and similarities; SA-USA: In the USA women are mostly ‘Corporate Entrepreneurs’ and in SA they are mainly ‘Entrepreneurs’. They agree that their associations are successful in promoting women in construction. 3. Positive pull factors are the main reason why women are in construction as they demonstrate entrepreneurial behaviour and characteristics. 4. Negative push factors, e.g. “need to make a living” are a lesser reason. 5. Gender discrimination can become fatal barriers for successful women entrepreneurs. 6. The majority of respondents see themselves as successful and intent on developing key aspects of their businesses to expand their competitive edge. 7. SAWiC played a pioneering role in developing a database to prevent clients from justifying their non-compliance of the law in terms of non-availability of women entrepreneurs in construction. / Thesis (PhD (Entrepreneurship))--University of Pretoria, 2006. / Business Management / unrestricted