Esta tese investiga as aproximações e os diálogos entre as artes, as técnicas e a cultura e de que modo eles reverberam no processo de formação e na prática dos arquitetos. O espaço aqui privilegiado é a Faculdade de Arquitetura e Urbanismo da Universidade de São Paulo dos anos 1950 a 1970. Trata-se de entender de que maneira a instituição se insere nos campos artístico, intelectual e profissional contemporâneos, especialmente em São Paulo, e, ao mesmo tempo, de que modo as relações com os meios artísticos adentram o espaço acadêmico, definindo não apenas um perfil de formação peculiar no período, mas também uma compreensão da arquitetura como atividade inseparável de outros ramos da cultura. Investigamos essas relações através da trajetória do professor, crítico e historiador da arte Flavio Motta, percorrendo sua carreira intelectual e docente desde a formação em Pedagogia na Faculdade de Filosofia, Ciências e Letras da USP nos anos 40, passando por suas experiências de trabalho com educação artística junto ao Museu de Arte de São Paulo e a Fundação Armando Alvares Penteado, até sua atuação decisiva na construção institucional e na reformulação acadêmica e político-pedagógica do curso de arquitetura da , ao longo dos quase 30 anos em que esteve ligado a esta escola. / This thesis investigates the approximations and dialogues between arts, techniques and culture and how they reverberate in architect\'s process of formation and practice. It is focused on the Faculdade de Arquitetura e Urbanismo da Universidade de São Paulo between 1950 and 1970. What it proposes is an understanding on how that institution inserts itself in the contemporary artistic, intellectual and professional fields, especially in São Paulo, and at the same time in which ways artistic fields entry academic space to the point of defining a particular formation in the mentioned period including architecture as an activity inseparable from other branches of culture. We investigate these relations looking at the trajectory of the professor, critic and art historian Flavio Motta. We go through his intellectual and teaching career from his degree in Pedagogy at the Faculty of Philosophy, Sciences and Letters of the USP in the 1940s, his experiences in artistic education at Museu de Arte de São Paulo and Fundação Armando Alvares Penteado, to his decisive role in the institutional construction and academic/ political-pedagogical reformulation of the architecture degree during almost 30 years he was connected to this school (eu colocaria FAU-USP invés de this school).

Les zéolithes représentent une importante classe de catalyseurs hétérogènes largement utilisées dans l’industrie. En effet, ce sont des catalyseurs de choix pour de multiples réactions grâce à leurs propriétés uniques largement modulables, à savoir leur forte acidité de Brønsted, leur grande surface spécifique, leur stabilité hydrothermique et leur sélectivité de forme. Cependant, la taille de leur micropores engendre des difficultés en terme de diffusion, réduisant ainsi leur potentiel catalytique. Ainsi, la conception sur mesure, en fonction de l’application finale, semble être une méthode très intéressante pour le développement de nouveaux catalyseurs zéolithiques.Les travaux réalisés au cours de cette Thèse ont pour objectif la conception de zéolithes à trois échelles : (i) au niveau du site actif en jouant sur la force acide et sur leur accessibilité, (ii) au niveau macroscopique par la taille des cristaux et (iii) au niveau du réacteur en les déposant sur divers supports. Ces différentes zéolithes ont été évaluées dans deux réactions acides : la chloration d’aromatiques et la conversion du méthanol en oléfines légères (MTO).Des zéolithes hiérarchisées ont été synthétisées selon diverses méthodes pré- ou post-Synthétiques et testées dans la chloration du nitrobenzène et du chlorobenzène. De plus, des cristaux « géant » de ZSM-5, préparés par voie fluorure, ont été évalués dans le MTO.La corrélation directe entre l’activité catalytique et les propriétés intrinsèques des zéolithes a permis de souligner les propriétés indispensables à chaque réactions. / Zeolites are aluminosilicate catalysts of great importance for the chemical industries. Their unique properties, i.e., strong Brønsted acidity, high surface area, high hydrothermal stability, and shape selectivity, combined with an extensive tunability, render them the candidate of choice in various reactions. Nevertheless, often only a fraction of their potential is exploited, due to access and diffusion limitation to/in their micropores. In this field, the rational design appears as a valuable method to design new zeolite catalysts, according to their targeted application.The work described in this Thesis aims in the design of zeolites at three levels: (i) acid site by playing on the acid strength and on the accessibility, (ii) microscopic scale by adapting the crystal size and (iii) reactor level by coating zeolite crystals on different supports. These as-Prepared zeolites were evaluated in two acid-Catalyzed reactions: the aromatics chlorination and the conversion of methanol in light olefins (MTO).Hierarchical zeolites were synthesized according to several pre- or post-Synthetic modifications and evaluated in nitro- and chlorobenzene chlorinations. Besides, “giant” ZSM-5 zeolites, prepared according to fluoride-Mediated route, as well as zeolite coatings on β-SiC, were tested in the MTO reaction.Thanks to a direct correlation between catalytic activities and intrinsic properties, optimal catalyst properties were highlighted in both reactions.

Made available in DSpace on 2016-06-02T19:55:36Z (GMT). No. of bitstreams: 1 5188.pdf: 6910424 bytes, checksum: 50b02c26311d2e058a7ac27b5419e05d (MD5) Previous issue date: 2011-06-08 / Environmental laws and stricter quality specifications have driven the development of technologies for improving the cetane number in diesel fuel. In addition to the saturation of (poly)aromatic compounds, responsible for limited gains, ring opening of at least one ring of (poly)cycloalkane, without loss of yield by cracking, is a promising strategy to maximize this property. Numerous studies have demonstrated the significant performance of Pt, Rh and Ir supported on zeolites for naphthenic ring opening in the hydroconversion of model compounds (naphthalene, tetralin and decalin). This study aimed to systematically assess the role of acid and hydrogenating functions for hydroconversion of decalin. It was also evaluated the effect of activation conditions (calcination and reduction), type of zeolite (Faujasite, FAU, or Beta, BEA), the content and type of metal (Pt, Ir or Rh). The influence of Pt-Ir and Pt-Rh bimetallic systems, as well as the inhibition by H2S, were studied in terms of the performance of these catalysts. For the catalytic precursors prepared, better activity and selectivity to ringopening products were obtained from calcination at 573 K and reduction at 713 K. This performance was consistent with a more homogeneous distribution of metallic particles on the support, and thus greater dispersion of the metallic phase. The reaction steps of ring contraction, ring opening and cracking were consecutive for the hydroconversion of decalin. It is noteworthy that the catalytic systems studied, under the operating conditions employed, yielded up to 45 mol% ring opening products and less than 15 mol% cracking products, at decalin conversions as high as 90 %. The Pt/BEA catalyst presented the best performance, thiotolerance (lower production of cracking products) and thioresistence (selectivity recovery after removal of H2S), followed by the Pt-It/BEA and Ir/BEA catalysts. This study allowed to highlight some peculiarities of the hydroconversion of decalin on noble metal/zeolite catalysts. Although decalin is a saturated molecule, his naphthenic character and probably the presence of a tertiary carbon in its structure, facilitates activation of the molecule directly on the strong acid sites of zeolite, even at relatively moderate temperatures. Thus, it is not necessary to form an olefin on a metal site and undergo subsequent protonation, as in a classical bifunctional mechanism, such as in hydroisomerization and hydrocracking of n-paraffins. However, the hydrogenation component of the catalyst influences the selectivity of the reaction, controlling the process of desorption/adsorption of any intermediate olefins formed. Greater hydrogenation activity implies lower availability of adsorbed carbocations that can be converted to cracking products. This proposition is consistent with the results obtained by varying the type and content of metal, support acidity and poisoning of the hydrogenation sites in the catalysts. / Legislações ambientais e especificações de qualidade mais restritivas têm impulsionado o desenvolvimento de tecnologias visando melhoria de cetano em óleo diesel. Adicionalmente à saturação de (poli)aromáticos, responsável por ganhos limitados, à abertura de pelo menos um anel do (poli)cicloalcano, sem perda de rendimento por craqueamento, consiste em estratégia potencial para maximização desta propriedade. Inúmeros trabalhos vêm demonstrando desempenho significante de catalisadores de Pt, Rh e Ir suportados em zeólitas para abertura de anel naftênico na hidroconversão de compostos-modelo (naftaleno, tetralina e decalina). O presente trabalho teve por objetivo avaliar sistematicamente o papel das funções ácidas e hidrogenantes para a hidroconversão de decalina. Foram abordados os efeitos das condições de ativação (calcinação e redução), do tipo de zeólita (Beta, BEA, ou Faujasita, FAU), do teor e do tipo de metal (Pt, Ir ou Rh). Também foi analisado o efeito de sistemas bimetálicos Pt-Ir e Pt-Rh, bem como a influência da inibição por H2S, no desempenho destes catalisadores. Para os precursores catalíticos preparados, melhores atividade e seletividade aos produtos de abertura de ciclo foram obtidas a partir da calcinação a 573 K e redução em 713 K. Este desempenho foi compatível com uma distribuição mais homogênea de partículas metálicas no suporte e, portanto, maior dispersão da fase metálica. As etapas reacionais de contração, abertura de ciclo e craqueamento são consecutivas para a hidroconversão de decalina. Destacam-se para os sistemas catalíticos estudados e condições operacionais empregadas, rendimentos de produtos de abertura de ciclo de até 45 %mol e craqueamento inferior a 15 %mol, obtidos para conversões de decalina tão elevadas quanto 90 %. O catalisador Pt/BEA apresentou melhores desempenho, tiotolerância (menor seletividade a craqueados na presença de H2S) e recuperação da seletividade após remoção do H2S, seguido pelo bimetálico de Pt-Ir/BEA e monometálico de Ir/BEA. O presente estudo permitiu colocar em evidência algumas peculiaridades da hidroconversão da decalina sobre catalisadores metal nobre/zeólita. Apesar de se tratar de uma molécula saturada, seu caráter naftênico e, provavelmente, a presença de um carbono terciário na sua estrutura, facilita a ativação da molécula diretamente sobre os sítios ácidos fortes da zeólita, mesmo em temperatura relativamente moderadas. Dessa forma, não necessita a formação de uma olefina num sítio metálico para posterior protonação, como num mecanismo bifuncional clássico de hidroisomerização e hidrocraqueamento de n-parafinas. A componente de hidrogenação do catalisador influencia, no entanto, a seletividade da reação, controlando o processo de dessorção/adsorção e hidrogenação das olefinas intermediárias formadas. Quanto maior a atividade hidrogenante, menor a disponibilidade de carbocátions adsorvidos que podem ser convertidos a produtos de craqueamento. Esta proposição é consistente com os resultados obtidos ao se variar o tipo e o teor de metal, a acidez do suporte e pelo envenenamento dos sítios de hidrogenação dos catalisadores.

Esta tese investiga as aproximações e os diálogos entre as artes, as técnicas e a cultura e de que modo eles reverberam no processo de formação e na prática dos arquitetos. O espaço aqui privilegiado é a Faculdade de Arquitetura e Urbanismo da Universidade de São Paulo dos anos 1950 a 1970. Trata-se de entender de que maneira a instituição se insere nos campos artístico, intelectual e profissional contemporâneos, especialmente em São Paulo, e, ao mesmo tempo, de que modo as relações com os meios artísticos adentram o espaço acadêmico, definindo não apenas um perfil de formação peculiar no período, mas também uma compreensão da arquitetura como atividade inseparável de outros ramos da cultura. Investigamos essas relações através da trajetória do professor, crítico e historiador da arte Flavio Motta, percorrendo sua carreira intelectual e docente desde a formação em Pedagogia na Faculdade de Filosofia, Ciências e Letras da USP nos anos 40, passando por suas experiências de trabalho com educação artística junto ao Museu de Arte de São Paulo e a Fundação Armando Alvares Penteado, até sua atuação decisiva na construção institucional e na reformulação acadêmica e político-pedagógica do curso de arquitetura da , ao longo dos quase 30 anos em que esteve ligado a esta escola. / This thesis investigates the approximations and dialogues between arts, techniques and culture and how they reverberate in architect\'s process of formation and practice. It is focused on the Faculdade de Arquitetura e Urbanismo da Universidade de São Paulo between 1950 and 1970. What it proposes is an understanding on how that institution inserts itself in the contemporary artistic, intellectual and professional fields, especially in São Paulo, and at the same time in which ways artistic fields entry academic space to the point of defining a particular formation in the mentioned period including architecture as an activity inseparable from other branches of culture. We investigate these relations looking at the trajectory of the professor, critic and art historian Flavio Motta. We go through his intellectual and teaching career from his degree in Pedagogy at the Faculty of Philosophy, Sciences and Letters of the USP in the 1940s, his experiences in artistic education at Museu de Arte de São Paulo and Fundação Armando Alvares Penteado, to his decisive role in the institutional construction and academic/ political-pedagogical reformulation of the architecture degree during almost 30 years he was connected to this school (eu colocaria FAU-USP invés de this school).

published_or_final_version / abstract / Architecture / Master / Master of Landscape Architecture

Orientador: Luiz Francisco Malmonge / Resumo: Nanocompósitos com matriz de fibras em escala micro e nanométrica de poli(fluoreto de vinilideno) – PVDF com adição de argila montmorilonita ou zeólita faujasita – FAU, nas concentrações de 3%, 5%, 10%, 20% e 30%, foram produzidas pela técnica de fiação por sopro em solução e submetidas a caracterizações morfológica e estrutural (Microscopia Eletrônica de Varredura – MEV, Difratometria de Raios X – DRX e Energia Dispersiva de Raios X – EDX). As análises térmicas foram feitas por Calorimetria Exploratória Diferencial – DSC e Análise Termogravimétrica – TGA; as mecânicas por análises de Tensão – Deformação; e de molhabilidade por Ângulo de Contato. As amostras foram submetidas a testes de remoção de metais pesados através da adsorção em banho e em membrana. Os resultados demonstraram queda da espessura dos nanocompósitos, que passaram de 500 μm do polímero puro, para 251 μm e 315 μm para os nanocompósitos com 30% de argila e FAU, respectivamente. A técnica de MEV evidenciou amostras com grande quantidade de fibras lisas, uniformes, cilíndricas e pouco aglomeradas, cujos diâmetros foram inferiores a 200 nm. A ferramenta de EDX confirmou a presença dos elementos da argila e da FAU dispersos por todo o filme, porém surgem aglomerados com o aumento de sua concentração. A técnica de DRX demonstrou a presença das fases cristalinas α e β da matriz, além disso, o aumento da quantidade de argila e FAU nos nanocompósitos intensificou seus picos característicos. A técnica DSC revelou que ... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

Made available in DSpace on 2016-06-02T19:56:40Z (GMT). No. of bitstreams: 1 3212.pdf: 9900982 bytes, checksum: fc5dfc8df72c2309a4e30ed6039ec097 (MD5) Previous issue date: 2010-07-21 / Universidade Federal de Minas Gerais / The FAU zeolite was obtained using different amounts of water. Both at higher levels as the lowest amount of water the intensities of the diffraction peaks are less intense. The results of physisorption of these samples suggest the presence of material not yet crystallized in this product. The scanning micrographs show large spherical particles with apparent roughness, suggesting the formation of aggregates of smaller particles. For transmission electron microscopy the results show very dense clusters, with indicative that the particles are very cohesive. The crystallization curve shows that the stabilization of the phase occurs at 8 h of synthesis at 100 ° C, be interesting to work on shorter times to prevent the growth of particles. The aging of the mixture facilitated the crystallization of the material by decreasing the induction time and particle size. In high alkalinity can be observed a decrease in the intensity of diffraction peaks and size of particles observed by SEM. Long crystallization times produce materials with high external area, about 40% higher than a commercial sample. The variation of aging time of the samples with high alkalinity shows that with three days are obtained clusters of about 100 nm are formed by crystals even smaller. Therefore, was developed a method to obtain nanocrystals of zeolite FAU, without the presence of template and using silica and alumina sources with reduced cost. / A zeólita FAU foi obtida em diferentes quantidades de água. Nos níveis mais altos e baixos de quantidade de água as intensidades dos picos de difração tornam-se menos intensos. O resultado de fisissorção dessas amostras sugere a presença de material não cristalizado ainda presente no produto. As micrografias de varredura mostram grandes partículas com contornos esféricos e aparente rugosidade, sugerindo a formação de agregados de partículas menores. Por microscopia eletrônica de transmissão os resultados mostram aglomerados bastante densos, indicando que as partículas estão bastante coesas. A curva de cristalização mostra que a estabilização da fase ocorre em 8 h de síntese a 100 °C, sendo interessante trabalhar em tempos inferiores para evitar o crescimento das partículas. O envelhecimento da mistura reacional facilitou a cristalização do material diminuindo o tempo de indução e o tamanho da partícula. Em alta alcalinidade pode ser observada a diminuição na intensidade dos picos de difração e no tamanho das partículas observadas por MEV. Maiores tempos de cristalização produzem materiais com elevada área externa, cerca de 40 % maior que uma amostra USY. A variação do tempo de envelhecimento das amostras com elevada alcalinidade mostra que com três dias são obtidos aglomerados de cerca de 100 nm formado por cristais ainda menores. Assim, foi desenvolvido um método para a obtenção de cristais nanométricos de zeólita FAU, sem a presença de direcionador orgânico e usando fontes de sílica e alumina de custo reduzido.

Ce travail présente la manière dont William Faulkner réfléchit la fonction identitaire de la narration dans plusieurs de ses romans : The Sound and the Fury, As I lay Dying, Light in August, Absalom, Absalom! et Requiem for a Nun. L’appartenance des personnages du corpus au Sud des États-Unis exacerbe leur faille constitutive, qu’ils cherchent alors à compenser par la médiation du récit. Cette thèse étudie, à travers le prisme de la théorie de la mimèsis de Paul Ricœur, comment ces personnages configurent leur temps vécu et se projettent mimétiquement dans leur récit afin de procéder à une herméneutique de soi et atteindre ainsi l’appropriation de soi qu’ils recherchent. Cependant, les narrateurs sont tous saisis d’un élan déconstructeur qui met en lumière l’irrésolution du langage grâce auquel ils essayent de se créer une identité de substitution. Ils prennent alors conscience que le langage se dissémine et que la présence qu’ils tentent de faire advenir se dérobe dès qu’elle apparaît. / This dissertation studies the issue of identity in several of William Faulkner’s novels (The Sound and the Fury, As I Lay Dying, Light in August, Absalom, Absalom! and Requiem for a Nun) and how characters attempt to retrieve a sense of self through narration. The characters’ belonging to the American South exacerbates their inner gap, which they then try to fill thanks to their story-telling. This study examines, through the prism of Ricoeur’s theory of mimesis, how these characters configure their world of action and project themselves mimetically into their narratives so as to achieve self-understanding through a hermeneutical process. However, the narrators under study are overwhelmed with a deconstructive impetus which sheds light on the indecisiveness of the language thanks to which they are trying to create a substitute identity. They thus become aware that language disseminates itself and that the presence they are attempting to create gives way as soon as it appears.

Les zéolithes sont des aluminosilicates cristallisés possédant une microporosité organisée et régulière de dimension moléculaire. Plus particulièrement, les zéolithes de type structural FAU sont très employées dans l’industrie comme tamis moléculaires, adsorbants ou catalyseurs grâce à leur faible coût de fabrication, leur grand volume poreux et leur large taille de pores. Cependant, leurs canaux purement microporeux limitent grandement la diffusion de molécules lors de réactions catalytiques ce qui affecte directement les vitesses de réaction et réduit la fraction utile de chaque cristal. L’objectif de cette thèse a été de créer une cavité interne (macroporosité) au sein de chaque cristal de zéolithe Y dont la taille globale et l’épaisseur de parois permettront de réduire les problèmes de diffusion tout en gardant des solides facilement manipulables. Durant cette étude, deux stratégies ont été imaginées et brevetées : la première consiste à préparer des capsules polycristallines de zéolithe Y en faisant croitre des nanocristaux de zéolithe Y en périphérie de cristaux de zéolithe Beta servant directement de nutriment et se détruisant au cours de la synthèse. La seconde stratégie consiste à éliminer le coeur de chaque cristal d’une zéolithe Y par une méthode de dissolution préférentielle. Une méthode multi-étapes alliant désalumination et désilication sélectives a été développée et a permis d’obtenir des monocristaux creux de zéolithe Y. Ensuite, dans le but de tester leurs propriétés diffusionnelles et catalytiques, ces deux nouveaux matériaux ont été imprégnés de nanoparticules de platine puis utilisés dans des réactions modèles d’hydrogénation et d’hydro-isomérisation. Dans le cas des monocristaux creux, ces réactions ont permis de mettre en évidence l’influence positive de la morphologie et plus particulièrement de la longueur de diffusion sur l’activité et l’efficacité catalytiques de ces nouveaux matériaux / Zeolites are crystalline microporous aluminosilicates whose structure contains channels, voids and cavities of molecular dimensions. Zeolites with FAU framework type are extensively used as molecular sieves, adsorbents or catalysts thanks to their low fabrication cost, their high porous volume and their large pore size. However, the intrinsic microporosity of these solids often imposes molecular diffusion limitations due to hindered access and slow intra-crystalline transport. The objective of this PhD thesis was to synthetize hollow Y zeolite crystals with an internal cavity (macroporosity) and walls sufficiently thin to reduce significantly diffusion limitations while preventing handling issues. During the PhD, two strategies have been developed to synthetize these materials. The first one consists in the synthesis of polycrystalline capsules of zeolite Y by overgrowing Y nanocrystals onto Beta zeolite crystals that serve as template as well as nutrients. The second strategy involves the selective removal of the core of each zeolite Y crystals through a multi-step original method combining dealumination and selective desilication. Stating from a standard NaY zeolite, this strategy enables effective preparation of hollow single crystals with well controlled morphology and composition. The influence of the morphology on diffusion and catalytic properties was estimated by comparing the activity of the platinum-impregnated new materials with those of bulk analogs in hydrogenation and hydro-isomerization model reactions. In the case of hollow single crystals, these reactions enable to highlight the positive influence of the morphology and particularly of the diffusion path length on the catalytic efficiency and activity of these new materials

Les zéolithes sont largement utilisées en catalyse. Un enjeu majeur est d'obtenir des cristaux nanométriques qui offrent des perspectives prometteuses dans la conception de catalyseurs acides plus actifs et plus sélectifs, notamment pour les procédés de conversion des coupes lourdes pétrolières. L'obtention de ces nano-cristaux peut résulter de l'utilisation d'inhibiteurs de croissance. Cette thèse s'est attachée à identifier deux familles de composés organiques limitant la croissance des cristaux. Pour la première, l'inhibition est envisagée par adsorption de composés organiques (polycations, acides aminés...) sur la surface des cristaux en formation. Cette étude a été réalisée en suivant une méthodologie d'expérimentation à haut-débit et a conduit à des cristaux de zéolithe Y (FAU) de 300 nm par l'ajout de L-lysine. La seconde famille est dérivée de l’approche de l’équipe de Ryoo et consiste en l’utilisation de composés bifonctionnels comportant une fonction structurante et une fonction inhibitrice de croissance. Cette étude a démarré par la synthèse de zéolithe MFI. La modélisation moléculaire a permis d'identifier un mono-ammonium alkylé favorisant la formation de nanofeuillets de zéolithe ZSM-5 d'épaisseur voisine de 2 nm. L'étude cinétique a révélé par ailleurs que cette zéolithe est synthétisée à partir d’un polysilicate lamellaire formé in situ. Cette stratégie d'identification, couplée à une méthodologie d'expérimentation à haut débit, a alors été appliquée à la synthèse des zéolithes EMC-1 (FAU) et EMC-2 (EMT), et a conduit à l'élaboration de nouveaux agents structurants et composés bi-fonctionnels. / Zeolites are widely used in catalysis. One of today’s major challenges is to obtain nanometer-sized crystals, offering promising prospects for the design of more active and more selective acid catalysts, in particular for heavy oil conversion processes. Zeolite nanocrystals can be obtained by using growth inhibitors. This thesis focused on the identification of two families of organic compounds limiting the crystals growth. For the first one, the growth inhibition is favored by the adsorption of organic compounds (polycations, amino acids…) on the surface of growing crystals. This study was conducted using a high-throughput experiment methodology and led to zeolite Y (FAU) crystals of 300 nm by the addition of L-lysine. The second family is derived from Ryoo’s team approach and consists of the use of bifunctional compounds including one structure-directing function and one growth-inhibiting function. This study started with the synthesis of MFI zeolite. The molecular modelling allowed identifying an alkyl mono-ammonium directing the formation of 2 nm-thick nanosheets of zeolite ZSM-5. The kinetic study revealed that this zeolite is synthesized from a lamellar polysilicate formed in situ. This identification strategy, coupled to a high-troughput experiment methodology, was applied to the synthesis of zeolites EMC-1 (FAU) and EMC-2 (EMT) and conducted to the elaboration of new structure-directing agents and their bifunctional counterparts.