Made available in DSpace on 2014-06-11T19:24:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-10Bitstream added on 2014-06-13T20:12:12Z : No. of bitstreams: 1 miguelneto_s_me_fran.pdf: 480331 bytes, checksum: bf2e559d33ba8f660e5c7da2dcefd097 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente estudo tem por escopo principal fixar, à luz das normas civis e das atividades desenvolvidas no comércio jurídico, a natureza, a amplitude e as características das obrigações propter rem. Assim, o exame acurado do tema produz a necessidade de se extrair das noções fundamentais postas pelo legislador e estudadas na doutrina, algumas características no amplo contexto dos direitos reais, fixando o objeto e delimitando os seus fundamentos; não obstante posições conflitantes entre os clássicos, a definição dos limites para a hipótese do estudo, surge dentro da área das obrigações reais, e o que é mencionado como obrigação propter rem. Não podemos nos eximir de classificá-la dentro do gênero obrigação real, espécie de obrigação adjetivada dessa forma, porque revestida da prerrogativa de estar vinculada a uma coisa. Nesse passo, são inúmeros os casos referentes à aplicação da obrigação propter rem, tratadas no novo Código Civil, especialmente entre os efeitos dos institutos mencionados no artigo 1.225, que tipifica os direitos reais por excelência, dos quais, decorre obrigação envolvendo a responsabilidade resultante da posse momentânea ou definitiva da coisa móvel ou imóvel. Com efeito, nos direitos de vizinhança, no uso normal ou anormal da propriedade, na passagem forçada, na passagem de cabos e tubulações, na propriedade alheia, nos limites entre os prédios e no direito de tapagem, no direito de construir, na titularidade e na garantia, vislumbra-se a modalidade em estudo. Vale dizer, que se as obrigações reais são as que estão a cargo de um sujeito de direito, na medida em que este é proprietário de uma coisa ou titular de um direito de uso e de gozo dela. As obrigações propter rem, por sua vez, correspondem a uma categoria especial de obrigação real. Contém um misto de direito real e direito pessoal, na medida...

Tendo como tema geral de pesquisa propostas e intervenções urbanas contemporâneas, o trabalho pretende discutir a natureza e distinções existentes entre os discursos, as propostas e ações, particularmente no campo cultural, formuladas e executadas na área da Estação da Luz da cidade de São Paulo pelos governos Marta Suplicy - 2001/2004 - e José Serra [e hoje seu substituto Gilberto Kassab], articuladas com as propostas do governo estadual, retrocedendo quando necessário ao entendimento das ações realizadas a partir das gestões de Luiza Erondina - 1989/1992 - no governo municipal e no primeiro governo de Mario Covas no Estado - 1995/1998 [e seu sucedâneo]. Desta forma, no contexto das mudanças econômicas ocorridas nos últimos 25/30 anos, que conheceram no plano urbano a noções de cidades globais, objetivou-se investigar criticamente o processo pelo qual a cultura e os equipamentos culturais têm adquirido um papel cada vez mais central nas práticas das chamadas políticas urbanas, valendo-se de ações que por vezes apresentam-se de forma antagônica, ao viés político dos governos, e por outro, não, em que pese o mesmo viés político. Isto salientou a necessidade de investigar as finalidades do Estado, nos seus vários níveis, e de seus parceiros preferenciais, nas intervenções dos espaços urbanos centrais da cidade contemporânea, num período em que estas ações surgem enquadradas por uma discussão internacional sobre o papel das cidades na economia contemporânea e o lugar do urbanismo e do planejamento urbano [estratégicos] nas políticas públicas. Enfim, a pesquisa teve como objeto de estudo as intervenções urbanas contemporâneas: o caso da área da Luz, no centro de São Paulo. A intenção foi, ao longo da pesquisa, pontuar os princípios que conduziram [até o momento] tais práticas, suas diretrizes e, principalmente, a forma com que o conjunto de relações sociais, econômicas, políticas e culturais transforma e modela os ambientes urbanos e o imaginário dos habitantes. Desta forma, o estudo das intervenções no centro histórico de São Paulo reconhece uma política de conjunto, mas parte da escolha e avaliação das ações propostas e efetivadas na área da Luz e antiga Cracolândia, um dos principais alvos do programa de requalificação urbana da prefeitura de São Paulo e, por isso, atualmente denominado Pólo Luz - Santa Ifigênia. Esta concentra uma série de questões presentes no que poderia ser definido como uma agenda de problemas e ações a ela associadas, mormente a revitalização das chamadas áreas degradadas, a partir da implementação de propostas e equipamentos culturais, que integram ou se espelham em modelos de políticas urbanas internacionais. Constituindo a pauta não só de arquitetos e urbanistas, mas também de várias outras áreas de conhecimento geografia, sociologia, economia, as discussões sobre a cidade requereram um razoável embasamento teórico, sendo a clareza dos conceitos envolvidos uma das metas estabelecidas a princípio. Motivou especialmente a percepção de que as noções de planejamento estratégico, competitividade entre as cidades, globalização e cidades globais saturaram o debate urbano contemporâneo e que a [s] ideologia [s] urbana [s] por interessa diversos acabava [m] por criar uma questionável impressão de coesão de conceitos que deveria ser posto à prova. Entre outros, George Simmel, Manfredo Tafuri, Fredic Jameson e Rem Koolhaas foram importantes aportes. / Having as a general subject of inquiry proposals and urban contemporary interventions, this dissertation intends to discuss and analyze the nature and existent distinctions between the speeches, the proposals and actions, particularly in the cultural field, formulated and executed in the area of Estação Luz in the city of São Paulo by the governments Marta Suplicy - 2001/2004 - and José Serra [and his current substitutive Gilberto Kassab], articulated with the proposals of the state government, retreating when necessarily to the understanding of the actions carried out from the managements of Luiza Erondina - 1989/1992 - in the municipal government and of the first government of Mario Covas in the state of São Paulo - 1995/1998 [and his substitutive]. In this way, in the context of the economical changes that took place in the last 25/30 years, that knew in the urban plan the notion of global cities, the goal was to investigate critically the process for which the culture and the cultural equipments have been acquiring a more and more central role in the practices of the socalled urban politics, using actions that for times show up in the antagonistic form, in function of the political slant of the governments, and for other, not, in what it weighs the same political slant. This pointed out the necessity to investigate the finality of the state, in its several levels, and of its main partners, in the interventions on the central urban spaces of the contemporary city, in a period in what these actions appear fitted by an international discussion about the role of the cities in the contemporary economy and the place of urbanism and of the [strategic] urban planning in the public politics. Finally, this inquiry has as objective of study the urban contemporary interventions: the case of the area of Luz in the centre of Sao Paulo. The intention along the inquiry was to punctuate the principles that conducted [until now] such practices, its directives and, mainly, the form with which the set of social, economical, political and cultural relations transforms and models the urban environments and the imaginary of its inhabitants. In this way, the study of the interventions in the historical centre of São Paulo recognizes a politics of set, but it breaks from the choice and evaluation of the actions proposed and brought into effect in the area of Luz and former Cracolândia, one of the main targets of the urban redesign programs of the city hall of São Paulo and, therefore, at present so-called Pólo Luz - Santa Efigênia. This area concentrates a series of present questions in what it might be defined as an agenda of problems and actions to them associated, chiefly the revitalization of the called degraded areas, from the implementation of proposals and cultural equipments, which they integrate or which mirror in models of international urban politics. Constituting the list not only of the architects and town planners, but also of several other areas of knowledge - geography, sociology, economy -, the discussions about the city demanded a reasonable theoretical foundation, being to clarity of the wrapped concepts one of the marks established on the beggining of this inquiry. It caused specially the perception of which the notions of strategic planning, competitiveness between the cities, globalization and global cities saturated the urban contemporary debate and that the urban[e] ideology[ies] marked by different interests ended for creating a questionable impression of cohesion of concepts that should be put to the test. Georg Simmel, Manfredo Tafuri, Fredric Jameson and Rem Koolhaas are important and essentials bases of this work.

The released particles during laser-based surface ablation of an epoxy resin coating were investigated for their number, size, mass and chemical composition. The laser used was a pulsed Nd:YAG laser with a maximum average power of 91 W. During the experiments, the applied laser power was investigated as a varying parameter. With the highest power, a maximum particle count of 4.3*108 particles/cm³ was measured, which corresponds to a mass of approximately 55 mg/m³. With decreasing laser power, the particle loading of the aerosol decreases. The particle sizes are bimodal distributed between 10 nm and approximately 3 μm. The first peak is at 34 nm and the second peak is at 630 nm. In terms of number, the nanoparticles dominate the distribution. During the analysis of the particles, fractal and spherical particles were determined, whereby the fractal particles are mainly in the nanometre range and the spherical particles mostly in the μm range. The chemical analysis of the particles showed that they consist of carbon and hydrogen.

Die mechanischen Eigenschaften eines Materials spielen eine entscheidende Rolle für mögliche Anwendungen. Für nanoskalige Metalle ist lange bekannt, dass sich deren mechanischen Eigenschaften von ihren bulk-Gegenstücken stark unterscheiden. In bulk-Metallen wird die Verformung durch die Wechselwirkung vorhandener Versetzungen kontrolliert. Dies erweist sich scheinbar auf der Nanoebene als weniger zutreffend, da nur wenige oder keine Versetzungen in nanoskaligen Proben vorhanden sind und diese einfach aus der Probe herauslaufen können, ohne dass es vorher zu einer Wechselwirkung kommt. Die Verformung wird dann bestimmt durch die Nukleation neuer Versetzungen. In dieser Arbeit wurde die Verformung von Gold-Nanodrähten mit einem Durchmesser zwischen 50 und 150nm, die entweder einkristallin oder entlang ihrer Länge verzwillingt waren, untersucht. Auf der einen Seite erfolgte die Durchführung der Versuche in-situ im Transmissionselektronenmikroskop, um die Entwicklung der Defektmorphologie direkt beobachten zu können. Auf der anderen Seite wurden ebenfalls Tests in-situ im Rasterelektronenmikroskop mit einem neu entwickelten Aufbau durchgeführt und dabei das Spannungs-Dehnungs-Verhalten der Nanodrähte analysiert. Sämtliche Nanodrähte zeigten anfänglich ein elastisches Verhalten mit einem Elastizitätsmodul, das größenunabhängig war und nahe an dem entsprechenden Wert für Bulk-Gold lag. Mit Beginn der plastischen Verformung entstehen planare Defekte homogen verteilt entlang der Drähte, sowohl bei einkristallinen als auch verzwillingten Drähten. Zusammen mit der gemessenen Nukleationsspannung zeigte dies eine gute Übereinstimmung mit existierenden Modellen für die Oberflächennukleation von leading-Partialversetzungen, die auf klassischer Nukleationstheorie basieren. Mit weiterer Verformung kommt es ebenfalls zur Nukleation von trailing-Partialversetzungen, wodurch bereits entstandene planare Defekte wieder verschwinden und im Fall von verzwillingten Drähten volle Versetzungen gespeichert werden. Da die Nukleation von trailing-Partialversetzungen durch die existierenden Modelle nicht vorhergesagt wird, öffnet diese Beobachtung neue Fragen, ob klassische Nukleationstheorie in der Lage ist, die Nukleation von Versetzungen korrekt darzustellen.

The chlorate process is very energy intensive and a major part of the production costs are for electrical energy. Since the electricity prices are constantly increasing and may also vary periodically, the chlorate plants may be forced to adjust their production rate to the price at each moment in order to minimise their costs. Variation of current load requires increased knowledge regarding the electrode behaviour in a wide current range. In this thesis, the aim was to study the impact of the electrolyte on the electrode reactions in order to reduce the energy consumption. The work has mainly been experimental and additionally mathematical modelling has been carried out. A wide current range has been investigated in order to increase the understanding of the phenomena and to obtain results useful for low-load operation during the periods of high electricity cost. To operate the anode as energy efficiently as possible, the anode potential should not exceed the critical potential (Ecr), where the slope of the anodic polarisation curve increases, most likely due to ruthenium(VIII)-formation, and where the side reaction of oxygen evolution increases. In this work, the influence of different electrolyte parameters on Ecr has been studied. It was shown that a higher chloride concentration and an increased temperature lowered Ecr, which was expected to increase the risk of exceeding Ecr. However, this was not observed due to a simultaneous favouring of the chloride oxidation. Hence it was concluded that the electrolyte parameters should be optimised so that the lowest possible anode potential is obtained, which would enable higher current densities without exceeding Ecr. A further conclusion is that the increased slope of the polarisation curve at Ecr was possibly related to the lower activity for chloride oxidation on ruthenium oxidised to ruthenium(VIII). At full-load operation, the cathode potential was shown to be rather independent of the electrolyte composition despite a large variation of electrolyte parameters. The cathode composition appears to be more critical than the electrolyte composition when aiming at reducing the energy consumption. A strategy to increase the cathode activity could be to in situ apply a catalytic film onto the electrode surface. Therefore, Y(III) was added to a chloride electrolyte in order to form a yttrium hydroxide film on the alkaline cathode surface during hydrogen evolution. The yttrium-hydroxide film activated reduction of water (hydrogen evolution) and hindered hypochlorite reduction, proton reduction and nitrate reduction. The inhibiting properties are important for the prevention of side reactions, which currently are avoided by reducing Cr(VI) of the electrolyte on the cathode, producing an inhibiting chromium-hydroxide film. The studies on Y(III) increase the expectations for finding alternatives to the toxic Cr(VI). The addition of chromate to the chlorate electrolyte gives a high cathodic current efficiency and chromate has buffering properties in the electrolyte. The role of the buffer has been investigated for the oxygen evolution from water (one possible anodic side reaction), as well as cathodic hydrogen evolution. Models have been developed for these systems to increase the understanding of the interaction between buffer, electrode reactions and mass transport; the results have been verified experimentally. The chromate buffer increased the limiting current significantly for the cathodic H+ reduction and the cathodic overpotential was reduced drastically at currents lower than the limited current. A too low overpotential could result in the cathodic protection being lost. The presence of chromate buffer increased the limiting current for the oxygen evolution from OH-. The modelling of these systems revealed that the homogeneous reactions connected to the electrode reactions were not in equilibrium at the electrode surface. Further, a good resolution of the interface at the electrode surface was crucial since the, for the electrode reactions, important buffering takes place in an nm-thick reaction layer. / Framställning av klorat är mycket energiintensiv och kräver stora mängder elenergi. Stigande elpriser, som dessutom ofta varierar under dygnet eller säsongsvis, gör att man vill reducera onödiga förluster samt ibland försöka anpassa produktionen så att man när elpriset är högt minskar den, för att sedan öka produktionen igen då elpriset sjunker. Denna flexibla drift kräver ny kunskap om hur elektroderna beter sig i ett större strömintervall än vad som tidigare varit av intresse. Målet med detta arbete var att, med fokus på elektrolytens betydelse, identifiera möjliga förbättringar för kloratprocessen och därmed minska energiförbrukningen. Studierna har i huvudsak varit experimentella men även matematisk modellering har använts. Ett brett strömintervall har undersökts för att bättre förstå fenomenen och för att även kunna använda resultaten då höga elpriser gör att man vill köra processen vid lägre laster än normalt. För att driften av anoden ska vara så energieffektiv som möjligt bör anodpotentialen inte överskrida den kritiska potentialen (Ecr), där den anodiska polarisationskurvan får en högre lutning (troligtvis pga Ru(VIII)-bildning) och bireaktionen syrgasutveckling ökar. I detta arbete har påverkan av olika elektrolytparametrar på Ecr undersökts. Det visade sig att en ökad kloridkoncentration och ökad temperatur sänkte Ecr. Trots att detta borde göra att Ecr lättare överskrids, blev inte detta fallet eftersom kloridoxidationen samtidigt gynnades. Slutsatsen blir därför att elektrolytparametrarna bör optimeras så att lägsta möjliga anodpotential uppnås, vilket då även gör att strömtätheten kan ökas utan att Ecr överskrids. Slutsatsen är vidare att polarisationskurvans högre lutning vid Ecr kan ha att göra med att rutenium oxiderat till rutenium(VIII) har lägre aktivitet för kloridoxidation. Vid full last visade sig katodens potential vara relativt oberoende av elektrolytsammansättningen trots att denna varierades kraftigt. Katodens sammansättning verkar vara viktigare att ta hänsyn till än elektrolytens för kunna åstadkomma en större energibesparing. Ett alternativ till att öka katodens aktivitet skulle vara att in-situ belägga elektrodytan med en katalytisk film. Försök gjordes att sätta till Y(III) till kloridelektrolyt för att under vätgasutveckling fälla ut en yttriumhydroxidfilm på den alkaliska katodytan. Yttriumhydroxidfilmen aktiverade vattenreduktion (vätgasutveckling) och inhiberade hypokloritreduktion, protonreduktion och nitratreduktion. De inhiberande egenskaperna är viktiga för att förhindra bireaktioner, vilka idag hindras av att Cr(VI) i elektrolyten reduceras på katoden och bildar en hindrande kromhydroxidfilm. Försöken med Y(III) visar att det finns goda möjligheter att hitta alternativ till det miljöfarliga Cr(VI). Kromattillsatsen i kloratelektrolyt ger förutom ett högt katodiskt strömutbyte även en buffrande effekt till elektrolyten. Effekten av buffert har undersökts för en av de anodiska bireaktionerna, syrgasutveckling ur vatten, samt för vätgasutvecklingen på katoden. Dessa system har modellerats för att bättre förstå samspelet mellan buffert, elektrodreaktioner och materietransport och resultaten har verifierats experimentellt. Kromatbufferten ökade gränsströmmen för katodisk H+-reduktion betydligt och katodöverpotentialen sjönk kraftigt vid lägre strömmar än gränsströmmen. Detta kan vara ett problem om överpotentialen sjunker så lågt att elektroden inte är katodiskt skyddad. För syrgasutvecklingen ökade närvaron av kromatbuffert gränsströmmen för syrgasutveckling ur OH-. Modellering av dessa system visar att de homogena reaktioner som var kopplade till elektrodreaktionerna inte var i jämvikt vid elektrodytan. Vidare visade det sig vara mycket viktigt med en bra upplösning av gränsskiktet vid elektrodytan, då den buffring som är viktig för elektrodreaktionerna sker i ett mycket tunt reaktionsskikt (nanometertjockt). / <p>QC 20100901</p>

Confronted with issues, whose (socioeconomic) causes cannot be resolved through the modification of the built environment, architectural interventions may often inadvertently aid the reproduction of the problems they seek to resolve. In eliminating symptoms of social inequality, alienation and marginalization, architecture can legitimize the social order out of which they arise. In such situations, architects’ attempts to concern themselves with narrowly practical concerns are insufficient even to their own aims, and in order to properly address the issues facing it, architecture must simultaneously operate as a vehicle for social critique and political emancipation. In the work of philosopher Slavoj Žižek, a critical-emancipatory intervention corresponds to an emphasis of a constitutive tension and discord (“the gap”) within what is commonly perceived as a stable, neutral background. Critique strives not to explicitly reveal existing problems. Instead, it reveals an inherent inconsistency within an implicit, ideological fantasy of order and harmony that allows us to naturalize these problems. Consequently, the critical-emancipatory potential of architecture resides not in its programmatic content nor in its representational image, but in its capacity to disrupt the reassuring affective texture of ideology. Critique resides in a formally subtle (concerning architecture in its narrowest definition as an affective structure), yet politically radical shift in how problems of everyday life are interpreted and processed; re-introducing a minimal sense of disquietude that is both critical and emancipatory. The disquietude, that marks an absence of a fantasy of order and harmony, can, paradoxically, only be sustained as a product of a formally (representationally) ordered and harmonious appearance. The critical-emancipatory disquietude is not a compromise of the order and harmony, but rather a reflection of its uncompromisingly egalitarian nature.

Dissertação (mestrado) - Pontifícia Universidade Católica do Paraná, Curitiba, 2008 / Bibliografia: f. 96-101 / Dois paradigmas são fundamentais na cidade contemporânea: as inovações tecnológicas como indutoras da configuração urbana e uma escala global mais forte do que a escala local. Apesar de marcantes na constituição urbana contemporânea, esses dois paradigmas / Two major paradigms underpin some conceptual ideas of the contemporary city:technological innovations and the relations between the global and the local scales. However, both paradigms could be tracked down to the beginning of the twentieth century, and f

A presente dissertação trata do direito de preferência para a celebração de negócios jurídicos, em geral translatícios de propriedade, que não encontra definição expressa no Código Civil, muito embora diversos dispositivos legais aludam ao referido direito. Na medida em que limita a liberdade contratual do vinculado à prelação, no tocante à escolha do outro contraente, a preferência, de origem legal ou negocial, atribui ao sujeito ativo da relação prelatícia o direito de ser preferido. Para tal, exige-se que o vinculado à preferência tenha decidido, de maneira livre e inequívoca, celebrar um contrato preferível, e que a sua intenção se tenha materializado, com a presença de um terceiro efetivamente interessado em com ele contratar. Constituído o direito do preferente, o que em geral chega a seu conhecimento por meio de notificação extrajudicial remetida pelo obrigado à prelação, pode aquele manifestar interesse em preferir, ou não. No primeiro caso, nasce na esfera jurídica do vinculado à prelação o dever de com ele contratar, nos mesmos termos e condições ajustados com terceiro. Dever este cuja violação, a depender da eficácia, real ou obrigacional, da preferência, possibilitará ao sujeito ativo perseguir não só as perdas e danos por ele eventualmente sofridas em decorrência do desrespeito a seu direito, como também, cumulativamente, lhe facultará exigir o cumprimento específico da obrigação. Neste último caso, o negócio jurídico celebrado entre o obrigado à preferência e terceiro será, perante o preferente, inoponível. / This thesis examines rights of first refusal to enter into a business transaction, generally involving the transfer of property. Rights of first refusal are not specifically defined in the Brazilian Civil Code, although various provisions of the Code allude to them. While on one hand rights of first refusal, whether legal or contractual in origin, limit the contractual freedom of the obligor, by restricting his choice of contracting parties, on the other they generate a preference or option in the right holder to conclude the transaction contemplated by the right. Before this preference or option can be exercised, however, the obligor must have formed the free and unmistakable intention to enter into the business transaction subject to the right of first refusal, and this intention must be made manifest in relation to a third party that is effectively interested in making the contract. The holder of the right of first refusal usually becomes aware that the right has become exercisable by notice sent by the obligor, and in response the right holder is required to state whether the right will be exercised or not. If the right is exercised, a new obligation arises on the part of the obligor to enter into the transaction with the right holder, on the same terms and conditions agreed with the third party. Depending on whether the right of first refusal is personal or real in nature, violation of this obligation can give rise not only to the right to reparation of losses suffered as a consequence of the breach, but also the right to demand specific performance of the obligation, in which case any transaction made between the obligor and a third party will be unenforceable against the holder of the right of first refusal.

Magister Legum - LLM (Criminal Justice and Procedure) / In the early 1990s Botswana faced rising levels of grand corruption and economic crimes in general. The laws could not cope with the high incidence of economic criminality, especially as regards the confiscation of dirty assets. At the time, the government relied solely on laws regulating the forfeiture of prohibited property and instruments of crime, given that there were no laws authorising the confiscation of proceeds of crime. The drivers of the said forfeiture laws are the Director of Public Prosecutions (DPP), the Botswana Police Service (BPS) and the Botswana Unified Revenue Service (BURS). Parliament then enacted the Proceeds of Serious Crime Act No. 19 of 1990 (PSCA). The PSCA was a three-pronged tool in that it introduced the offence of money-laundering, enhanced investigative powers, and authorised conviction-based confiscation of proceeds of crime. The DPP was tasked with conducting criminal prosecutions and applying for confiscation orders. The BPS was mandated to conduct financial investigations.

A presente dissertação trata do direito de preferência para a celebração de negócios jurídicos, em geral translatícios de propriedade, que não encontra definição expressa no Código Civil, muito embora diversos dispositivos legais aludam ao referido direito. Na medida em que limita a liberdade contratual do vinculado à prelação, no tocante à escolha do outro contraente, a preferência, de origem legal ou negocial, atribui ao sujeito ativo da relação prelatícia o direito de ser preferido. Para tal, exige-se que o vinculado à preferência tenha decidido, de maneira livre e inequívoca, celebrar um contrato preferível, e que a sua intenção se tenha materializado, com a presença de um terceiro efetivamente interessado em com ele contratar. Constituído o direito do preferente, o que em geral chega a seu conhecimento por meio de notificação extrajudicial remetida pelo obrigado à prelação, pode aquele manifestar interesse em preferir, ou não. No primeiro caso, nasce na esfera jurídica do vinculado à prelação o dever de com ele contratar, nos mesmos termos e condições ajustados com terceiro. Dever este cuja violação, a depender da eficácia, real ou obrigacional, da preferência, possibilitará ao sujeito ativo perseguir não só as perdas e danos por ele eventualmente sofridas em decorrência do desrespeito a seu direito, como também, cumulativamente, lhe facultará exigir o cumprimento específico da obrigação. Neste último caso, o negócio jurídico celebrado entre o obrigado à preferência e terceiro será, perante o preferente, inoponível. / This thesis examines rights of first refusal to enter into a business transaction, generally involving the transfer of property. Rights of first refusal are not specifically defined in the Brazilian Civil Code, although various provisions of the Code allude to them. While on one hand rights of first refusal, whether legal or contractual in origin, limit the contractual freedom of the obligor, by restricting his choice of contracting parties, on the other they generate a preference or option in the right holder to conclude the transaction contemplated by the right. Before this preference or option can be exercised, however, the obligor must have formed the free and unmistakable intention to enter into the business transaction subject to the right of first refusal, and this intention must be made manifest in relation to a third party that is effectively interested in making the contract. The holder of the right of first refusal usually becomes aware that the right has become exercisable by notice sent by the obligor, and in response the right holder is required to state whether the right will be exercised or not. If the right is exercised, a new obligation arises on the part of the obligor to enter into the transaction with the right holder, on the same terms and conditions agreed with the third party. Depending on whether the right of first refusal is personal or real in nature, violation of this obligation can give rise not only to the right to reparation of losses suffered as a consequence of the breach, but also the right to demand specific performance of the obligation, in which case any transaction made between the obligor and a third party will be unenforceable against the holder of the right of first refusal.