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SILVA, Gustavo Souza de Alencar e. "Sinterização por SPS de pós de W-C-CO-B preparados por moagem de alta energia." Universidade Federal de Alfenas, 2016. https://bdtd.unifal-mg.edu.br:8443/handle/tede/1057.
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Os carbetos de tungstênio com matriz de cobalto são uns dos mais antigos produtos comerciais da metalurgia do pó. Estes compósitos são usados para diferentes aplicações dentre as quais se destacam a fabricação de componentes de corte e abrasivos. Tais materiais são constituídos por partículas de carbeto de tungstênio e cobalto metálico ligados pela sinterização via fase líquida e podem ser produzidos por reações químicas convencionais. As técnicas de moagem de alta energia são amplamente utilizadas para a síntese de compostos cerâmicos. O presente trabalho visou a realização de estudos de moagem de alta energia e de sinterização de misturas de pós de carbeto de tungstênio dopados com cobalto e boro. A etapa de moagem das misturas de pós elementares de W-50C (%-at.) foi realizada em um moinho de bolas planetário Fritsch P-5 utilizando esferas (10 mm de diâmetro) e vaso de WC-Co, velocidade de 200 rpm e uma relação de massas esferas-pós de 10:1. O tempo de moagem foi variado: 20, 60, 180 e 600 min. Na sequência, os pós de Co e de B foram misturados com os pós moídos de W-50C (%-at) e processados em um moinho Spex por 5 min. Seguindo, os materiais foram sinterizados em atmosfera controlada à 1450oC para a obtenção de corpos cilíndricos com altura de 1-3 mm e diâmetro de 10 mm. Os pós-moídos e os produtos sinterizados foram avaliados com o auxílio das técnicas de difração de raios X (DRX), microscopia eletrônica de varredura (MEV), espectrometria por dispersão de energia (EDS) e ensaios mecânicos (compressão diametral e dureza Vickers). Picos de carbono desapareceram após 180 min de moagem, enquanto que o pico principal do tungstênio foi deslocado para a direção de menores ângulos de difração em pós de W-50C moídos por 600 min. Ainda, os picos de tungstênio foram alargados e tiveram suas intensidades reduzidas em misturas de pós de W-50C moídos por 600 min, sugerindo que os átomos de carbono ficaram dissolvidos na estrutura cristalina do tungstênio para formar soluções sólidas supersaturadas. Amostras densas (> 96% da massa específica teórica) com microestruturas formadas pela fase WC como matriz além de precipitados ricos em boro e de W2C foram obtidos após spark plasma sintering das misturas de pós contendo adição de boro. As amostras sinterizadas apresentaram valores de dureza Vickers entre 1841 HV e 2191 HV, as quais foram mais pronunciadas para as cerâmicas mais ricas em boro. Similarmente à cerâmica convencional de WC-6Co, nenhum efeito foi encontrado sobre a adição de boro no módulo elástico das cerâmicas avaliadas, as quais ficaram próximas de 500 GPa. Ao contrário, a resistência compressiva das cerâmicas de WC-6Co contendo adição de boro ficou inferior a 500 MPa.Tungsten carbides in cobalt matrix are one of the earliest commercial products of powder metallurgy. These composites are used for different applications among which are highlighted the manufacture of cutting components and abrasives. These composites consist of tungsten carbide and metallic cobalt particles bound by sintering through the liquid phase and they can be produced by conventional chemical reactions. Mechanical alloying techniques are widely used for the synthesis of ceramic compounds. The present work aims to perform studies of mechanical alloying and sintering of powder mixtures of tungsten carbide doped with cobalt (6 wt.-%) and boron (0.2 and 0.5 at.%). Ball milling of W-50C (at.-%) elemental powder mixtures was performed in a planetary Fritsch P-5 ball mill using WC-Co balls (10 mm diameter) and vial (500 mL), rotary speed of 200 rpm, and a ball-to-powder weight ratio of 10:1. The milling time was varied: 20, 60, 180 and 600 minutes. Following, the powders of Co and B were mixed for 5 min in a Spex mill together the previous mechanically alloyed W-50C (at.-%) powders. Afterwards, the as-milled powders were consolidated by spark plasma sintering (SPS) at 1450°C under controlled atmosphere to obtain cylindrical bodies with height of 1-3 mm and 10 mm diameter. The as-milled powders and sintered products were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and mechanical tests (diametrical compression and Vickers hardness). Peaks of carbon disappeared after milling for 180 min whereas the major W peak was shifted toward the lower diffraction angles in W-50C powders milled for 600 min. In addition, the peaks of W were broadened and their intensities reduced after milling for 600 min, suggesting that the carbon atoms were dissolved into the W lattice in order to form supersaturated solid solutions. SPS process of mechanically alloyed W-50C powders containing Co and B produced dense samples (> 96% of theorical specific mass) which presented microstructures formed by the WC phase as matrix beside the B-rich and W2C precipitates. SPS samples presented Vickers hardness values between 1841 HV and 2191 HV which were more pronounced for B-richer ceramics. For the evaluated ceramics, no effect of boron addition on the elastic module was found, which were close to 500 GPa. On the other hand, the compressive strenght of W-50C ceramics containing Co and B addition were lower than 500 MPa.
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
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Granone, Luis Ignacio [Verfasser], Detlef [Akademischer Betreuer] Bahnemann, Nadja-C. [Akademischer Betreuer] Bigall, and Cecilia B. [Akademischer Betreuer] Mendive. "An iron-based photoelectrode / Luis Ignacio Granone ; Detlef W. Bahnemann, Nadja-C. Bigall, Cecilia B. Mendive." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2019. http://nbn-resolving.de/urn:nbn:de:101:1-2019091902085894972941.
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Doukas, Georgios. "Pierre Boaistuau (c. 1517-1566) and the employment of humanism in mid sixteenth-century France." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3239/.
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This study examines the manifestations of French humanism in sixteenth-century intellectual culture, through an analysis, for the first time, of the entirety of the works of Pierre Boaistuau. An eminent French humanist writer, on whose life little information exists, Boaistuau emerges far more prolific than any previous study has hitherto recognised. Thus, on a first level, his case offers the opportunity for an exploration of the developments of French print culture at the time. In addition, careful examination of the contents of his widely circulated works sheds new light on the ways humanist themes and values were incorporated into contemporary literary production, and were used for different purposes which surpassed the mere celebration of ancient learning. Boaistuau employed seven genres in order to compile seven books of different natures, all of them however grafted onto a humanist framework. Associated with narrative fiction, Renaissance philosophy, political theory, the study of history, and natural philosophy, his works demonstrate how the classical past and the humanist values of virtue, erudition, and self-discipline were used in a variety of ways in mid sixteenth-century France: for promotion of a moralising message, praise of the French monarchy, bolstering the Catholic faith, and enhancing the understanding of the natural world.
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Malavialle, Philippe. "Infections virales en transplantation hépatique : à propos des 104 premiers greffés." Bordeaux 2, 1992. http://www.theses.fr/1992BOR23053.
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Kemble, Roger. "Urban design requirements, B. C. Place Vancouver, B. C." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26852.
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A new set of urban design requirements is proposed to replace the current urban design guidelines for the B. C. Place site in Vancouver, B. C. The site is 90.6 hectares of open area, contiguous to the downtown, it is the subject of extensive planning activities. The site has been chosen because it is free of most of the typical impediments that constrain urban planning in more congested areas of the city. Accordingly, a new way of expressing urban space is appropriate.
To be valid urban design requirements must be conceived with a purpose in mind. The purpose, here, is the essential element of urban design, a shared vision of urban space. It must define, within a broad public consensus, a set of urban design requirements communicating, over an extended time period, a consistent vision of urban space.
Six urban design requirements are set out to implement a shared vision of urban space. They have been reduced to a minimum to provide as much freedom of expression to the design professions as possible. They are under six headings: Interim Land Use, Site Development, Physical Form and Design, Environment, Occupancy, and Movement.
Pivotal in the composition of the urban design requirements is an instrument called the Orthodox Surface Modulator, augmented by a Check List of architectural design elements. Together they become a metaphoric framework of reference, a part of the creative process within the development control system.
The Orthodox Surface Modulator, as it is applied, describes the volumetric forms of building envelopes and the public urban spaces between buildings. It describes buildings and spaces to enhance public amenity. It may, under specific environmental circumstances, mitigate undesirable site conditions by describing building envelopes as buffer buildings, shielding passive urban space from noise and distractions.
Urban Space is discussed. A Shared Vision of Urban Space, how it is evolved by public discourse, and a proposed Theory of Urban Space is explained. A critique of current urban development on Burrard Street, Vancouver, between Georgia Street and the waterfront explains why the present urban design guidelines, transfer of development rights and bonusing, have failed to produce the intended urban spatial amenity.
Urban design requirements are not a new phenomenon. Only since the early 1970s have they taken on their present complex form in the City of Vancouver. A brief historic outline traces the antecedents of the proposed urban design requirements, placing them in context from early Greek attempts to rationalize optical distortion to the present day.
The proposed application of the six urban design requirements and the Surface Modulator would be mandatory. The manner in which the elements of the Check List are integrated into the matrix of the Surface Modulator is proposed to be discretionary. The complete set of urban design requirements are intended to be used in a negotiating procedure common in planning practice.Applied Science, Faculty of
Community and Regional Planning (SCARP), School of
Graduate
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Parra, Gómez Cristián, and Díaz Braulio Cid. "C&B Servicios." Tesis, Universidad de Chile, 2016. http://repositorio.uchile.cl/handle/2250/143370.
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TESIS PARA OPTAR AL GRADO DE MAGÍSTER EN ADMINISTRACIÓN
Cristián Parra Gómez [Parte I], Braulio Cid Díaz [Parte II]En el barrio industrial de la bahía Mejillones existen algunas empresas de manufactura dedicadas esencialmente a generar productos para la minería del cobre de la segunda región (energía, explosivos, insumos y servicios), cuya operación se ve supeditada al cumplimiento de estrictos estándares ambientales: control de emisiones de riles, gases, material particulado, residuos sólidos, etc. En particular, el control de emisión de gases y material particulado se ha logrado a través de procesos y equipos específicos para esa tarea, cuya disponibilidad y confiabilidad se torna esencial para la sustentabilidad económica, social y ambiental de las empresas. Por otro lado, en la segunda región se encuentran las industrias de mayor tamaño del país: Codelco con las divisiones Chuquicamata, Radomiro Tomic, Gabriela Mistral y Ministro Hales; BHP Billiton con Minera Escondida, Glencore con Lomas Bayas, y Antofagasta Minerals con Antucoya, Centinela y Zaldívar, lo que ha atraído la presencia local de grandes empresas de servicios nacionales e internacionales con la intención de capturar parte del valor creado por las mencionadas industrias, en desmedro de las operaciones industriales de la bahía de Mejillones. Finalmente, y a pesar del explosivo desarrollo que ha vivido la comuna de Mejillones en los últimos quince años, no se ha desarrollado una industria de servicios capaz de atender las operaciones industriales de la bahía de Mejillones, básicamente por falta de preparación técnica y de administración. Considerando lo expuesto, se presenta la oportunidad para ofrecer a las industrias de la bahía de Mejillones servicios de mantenimiento e ingeniería para sus equipos de tratamiento de gases, oportunos y de alta calidad técnica, a objeto de asegurar la disponibilidad y confiabilidad de los mismos. Se presenta en este documento la descripción y evaluación a cinco años del proyecto de empresa “C&B Servicios”, cuyo resultado financiero para una inversión inicial de M$ 133.366 es un valor presente neto de M$ 309.956 (que incluye el valor terminal de M$ 885.713) con una tasa interna de retorno de 39%. Al quinto año, la rentabilidad esperada sobre el patrimonio es de 274%, con un valor de M$ 462.182.
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Onyema, Ezenwa Chizimako Sunny. "Mechanism for synthesis of K* Arachno-C₂B₇H₁₂· from Arachno-4,5-C₂B₇H₁₃, and fluxional behavior of Nido-4,5-C₂B₆H₁₀." Click here for download, 2006. http://wwwlib.umi.com/cr/villanova/fullcit?p1434394.
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Greiwe, Peter. "Synthese von Heterodiborolanen und Aufbau von nido-Hexaboranen mit den Gerüstatomen C 2 B 3 N, C 2 B 3 S und C 5 B." [S.l. : s.n.], 2000. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8832639.
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STADLER, MICHAEL. "Proteines de la structure r b c c et transcription." Paris 7, 1999. http://www.theses.fr/1999PA077260.
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Les proteines r b c c sont caracterisees par la presence, de l'aminoterminus au carboxyterminus, des trois motifs ring, boite b et coiled coil. Le doigt de zinc du type ring (c 3hc 4) fait partie des interactions intermoleculaires dans des complexes multiproteiques et pourrait jouer un role dans leur assemblage ou stabilisation. Il est aussi responsable, en collaboration avec la boite b, de la localisation compartementalisee subcellulaire des proteines. Le doigt de zinc du type boite b (chc 3 - 4h 2) est implique dans des interactions proteine-proteines, par exemple dans la liaison de pml a rb1. Le domaine de dimerisation par helices hydrophobes (coiled coil) est une super-helice des helices et participe a la dimerisation, ensemble avec la boite b : le coiled coil comme surface d'interaction, la boite b peut-etre comme stabilisateur de l'orientation du coiled coil. Les trois domaines constituent le motif tripartie qui semble jouer un role fondamental dans l'adressage ou l'assemblage des macromolecules. Les membres les mieux etudies de cette famille multiproteique sont pml et les tif1. Pml est une proteine avec des capacites multiples de regulation : elle fait partie des complexes transcriptionnellement actifs, elle reprime (a travers l'apoptose) la croissance et la transformation, et elle controle des fonctions immunitaires, sous influence de l'acide retinoique et des interferons. Nous avons pu eclaircir le mecanisme moleculaire de l'induction transcriptionnelle de pml par les interferons avec l'identification d'elements fonctionnels de reponse aux interferons dans le promoteur de pml. Pml est fusionne au recepteur de l'acide retinoique, rar dans la translocation t(15 ; 17) specifiquement rencontree dans la vaste majorite
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Eberling-Fux, Nicolas. "Matériaux composites à matrice nanostructurée dans les systèmes Si-B-C-Ti et Si-B-C-N." Bordeaux 1, 2006. http://www.theses.fr/2006BOR13235.
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Des matériaux composites à matrice céramique micro-nanostructurée et renfort fibreux en carbone ont été élaborés dans le système Si-B-C-X (X = Ti, N) par l'intermédiaire d'un nouveau procédé hybride alliant fiabilité, rapidité et minimisation des coûts. Ce dernier combine une étape d'imprégnation de préformes 3D (environ 2 mm d'épaisseur) à partir de suspensions de poudres céramiques nanométriques carbures et borures, suivie d'une étape de densification de la matrice pulvérulentes du composite. L'objectif repose sur la conception d'une matrice multiphasée amélirée présentant une ou des phases réfractaires, une phase borée assurant les mécanismes d'autocicatrisation dès 600°C et un phase déviatrice de fissures. Les applications envisagées sont aéronautiques pour un domaine de température de 600°C à 1100°C. Deux voies d'élaboration ont été explorées suivant la nature de la suspension initiale, à savoir des suspensions de poudres de carbure de silicium ou de carbure de titane dans lesquelles une poudre de carbure ou de nitrure de bore est ajoutée. Dans le cas de suspensions à base de poudres de SiC, le mélange de particules est dispersé dans un système suspensif à base d'éthanol et de polyéthylène imine. Les préformes avec ou sans interphase sont imprégnées à coeur de matériau et présentent des taux de remplissage compris entre 55 % et 70 % pour des temps d'exposition de 1 à 2 min. Ces dernières sont ensuite densifiées par frittage flash ou par infiltration réactive à partir de titane ou d'alliages fondus de manière à former respectivement des composites Cr / SiC - B4C ou SiC - BN, et des composites Cf / SiC(TIC) - TiB2 - Ti3SiC2. Le nitrure de bore et la phase ternaire Ti3SiC2 joue le rôle de fusible mécanique et d'interphase discrète au sein de la matrice composite. Dans le cas de suspensions à base de poudres de TiC, les particules sont préalablement soumises à un traitement acide en vue d'améliorer la dispersion du mélange de poudre dans le système éthanol + polyethylène imine. Présentant des taux d'imprégnation compris entre 50 % et 60 %, le matériau préimprégné est ensuite infiltré par du silicium ou un de ses alliages de manière à réaliser des composites à matrice SiC(TIC) - TiB2 - Ti3SiC2. L'ensemble des matériaux élaborés est caractérisé d'un point de vue morphologique, physico-chimique et mécanique. Des corrélations structure - propriétés sont établies.
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GERVAIS, CHRISTEL. "Etude par resonance magnetique nucleaire a l'etat solide de divers polymeres, precurseurs de ceramiques b-n, si-c-n, si-b-c-n et si-b-c-o." Paris 6, 1999. http://www.theses.fr/1999PA066210.
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L'elaboration de ceramiques a partir de precurseurs polymeres est une voie de synthese qui s'est beaucoup developpee recemment pour permettre l'elaboration de materiaux composites et remedier a la fragilite des ceramiques massives. Les grandes possibilites de mise en forme offertes par des polymeres solubles ou fusibles va en effet faciliter la fabrication de composites a renfort fibreux presentant d'excellentes proprietes mecaniques et qui trouvent par exemple leur application dans le secteur aeronautique et spatial. L'objet de ce travail est d'evaluer les potentialites qu'offre la rmn a l'etat solide pour caracteriser la conversion de precurseurs polymeres en ceramiques de type nitrure et borure. Cette voie d'elaboration conduit a l'obtention de composes complexes et peu organises dont la caracterisation structurale est relativement difficile. Toutefois, un reel developpement de ces procedes necessite une bonne comprehension des processus mis en jeu lors de la transformation du polymere en ceramique. Nous nous sommes interesses a differents polymeres preceramiques dans les systemes b-n, si-c-n, si-b-c-n et si-b-c-o : nous avons ete amenes a mettre en oeuvre differentes methodes rmn haute resolution a l'etat solide axees plus particulierement sur l'etude des noyaux 1 1b et 1 5n en essayant de contourner les difficultes afferentes a ces derniers (l'existence d'une interaction quadripolaire difficile a moyenner pour 1 1b et une tres faible sensibilite pour 1 5n). Nous avons d'une part tire profit de la presence de protons : elle a permis d'augmenter la sensibilite de spins peu abondants ( 1 3c, 1 5n et 2 9si) mais aussi de sonder l'environnement protone des differents noyaux etudies grace aux techniques de polarisation croisee. Les methodes les plus recents de rmn haute resolution des noyaux quadripolaires ont egalement ete mises en oeuvre (mq-mas, mas a hauts champs) afin d'apprehender les differents environnements du bore au sein d'une meme coordinence.
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Lee, Kang-sang. "New Concepts and Catalysts for Enantioselective Synthesis of C-C, C-Si, and C-B Bonds." Thesis, Boston College, 2010. http://hdl.handle.net/2345/1739.
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Thesis advisor: Amir H. HoveydaChapter 1. The development of chiral monodentate N-heterocyclic carbenes (NHCs) is presented. Structurally varied twenty-eight new chiral imidazolinim salts, NHC precursors, were synthesized and characterized. Chapter 2. The first example of Cu-catalyzed enantioselective conjugate additions of alkyl- and arylzinc reagents to unactivated cyclic enones is presented. Transformations are promoted in the presence of 2.5-15 mol % of a readily available chiral NHC-based Cu complex, affording the desired products bearing all-carbon quaternary stereogenic centers in 67-98% yield and in up to 97% ee. Catalytic enantioselective reactions can be carried out on a benchtop, with undistilled solvent and commercially available (not further purified) Cu salts. Chapter 3. A new class of enantioselective conjugate addition (ECA) reactions that involve aryl- or alkenylsilylfluoride reagents and are catalyzed by chiral non-C2-symmetric Cu-based NHC complexes are presented. Transformations have been designed based on the principle that a catalytically active chiral NHC-Cu-aryl or NHC-Cu-alkenyl complex can be accessed from reaction of a Cu-halide precursor with in situ-generated aryl- or alkenyl-tetrafluorosilicate. Reactions proceed in the presence of 1.5 equivalents of the aryl- or alkenylsilane reagents and 1.5 equivalents of tris(dimethylamino)sulfonium difluorotrimethylsilicate. Desired products are isolated in 63-97% yield and 73.5:26.5-98.5:1.5 enantiomeric ratio (47%-97% ee). Chapter 4. An efficient Cu-catalyzed protocol for enantioselective addition of a dimethylphenylsilanyl group to a wide range of cyclic and acyclic unsaturated ketones, esters, acrylonitriles and dienones is presented. Reactions are performed in the presence of 1-5 mol % of commercially available and inexpensive CuCl, a readily accessible monodentate imidazolinium salt as well as commercially available (dimethylphenylsilyl)pinacolatoboron. Cu-catalyzed 1,4- and 1,6-conjugate additions afford the enantiomerically enriched silanes in 72%-98% yield and 90:10->99:1 enantiomeric ratio (er) with up to >25:1 of Z:E selectivity. Chapter 5. A Cu-catalyzed method for enantioselective boronate conjugate additions to trisubstituted alkenes of acyclic a,b-unsaturated carboxylic esters, ketones, and thioesters is presented. All transformations are promoted by 5 mol % of a chiral monodentate NHC-Cu complex, derived from a readily available C1-symmetric imidazolinium salt, and in the presence of commercially available bis(pinacolato)diboron. Reactions are efficient (typically, 60% to >98% yield after purification) and deliver the desired boryl carbonyls in up to >98:2 enantiomer ratio (er). In addition, metal-free, nucleophilic activation of a B-B bond has been exploited in the development of a highly efficient method for conjugate additions of commercially available bis(pinacolato)diboron to cyclic or acyclic a,b-unsaturated carbonyls. Reactions are readily catalyzed by 2.5-10 mol % of a simple NHC. A variety of cyclic and acyclic unsaturated ketones and esters can serve as substrates. Transformations deliver boryl carbonyls bearing tertiary as well as quaternary B-substituted carbons in up to >98% yield
Thesis (PhD) — Boston College, 2010
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Boner, Winifred. "HBV pre-C/C variation : geographical and functional aspects." Thesis, University of Glasgow, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360172.
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Jiang, Tuo. "Palladium(II)-Catalyzed Oxidative Carbocyclization : Stereoselective Formation of C–C and C–B Bonds." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-108669.
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Transition metal catalysis has emerged as one of the most versatile methods for the selective formation of carbon–carbon and carbon–heteroatom bonds. In particular, oxidative carbon–carbon bond forming reactions have been widely studied due to their atom economic feature. This thesis has been focused on the development of new palladium(II)-catalyzed carbocyclization reactions under oxidative conditions. The first part of the thesis describes the palladium(II)-catalyzed oxidative carbocyclization-borylation and -arylation of enallenes. In these reactions, the (σ-alkyl)palladium(II) intermediate, which was shown previously to undergo β-hydride elimination, could be trapped in situ by organoboron reagents (B2pin2 and arylboronic acids) to form new carbon–boron and carbon–carbon bonds. Through these two protocols, a range of borylated and arylated carbocycles were obtained as single diastereomers in high yields. The second part deals with a palladium(II)-catalyzed oxidative diarylative carbocyclization of enynes. The reaction was proposed to start with a syn-arylpalladation of an alkyne, followed by insertion of the coordinated alkene. Subsequent arylation afforded a series of valuable diarylated tetrahydrofuran and tetrahydropyran products. The final part of the thesis advances the previously developed palladium(II)-catalyzed oxidative carbocyclization-borylation of enallenes in an enantioselective manner. C2-symmetric chiral phosphoric acids were used as the novel co-catalyst to trigger the enantioselective formation of intramolecular carbon–carbon bonds. By using this chiral anion strategy, a number of enallenes were converted to the borylated carbocycles with high to excellent enantioselectivity.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.
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Tenembart, Olivier. "Mechanistic studies of the vitamin B₁₂-catalysed C,C-bond formation /." [S.l : s.n.], 1987. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Eltis, Lindsay David. "Interaction of cytochrome b₅ and cytochrome c." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/29096.
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The interaction and kinetics of electron transfer between cytochrome b₅ and cytochrome c, two well characterised soluble electron transfer proteins, have been investigated by three techniques. First, fluorescence quenching experiments were done with cytochrome b₅ and porphyrin cytochrome c, a fluorescent analogue of cytochrome c. These quenching studies yielded association constants and structural information for the cytochrome b₅ cytochrome c complex. Second, an analysis of the rate of flavin semiquinone reduction of the cytochromes within the cytochrome b₅ cytochrome c complex yielded information about the structure and electrostatics of die complex. Third, the second order rate constant for ferrocytochrome b₅ reduction of ferricytochrome c was determined under a variety of solution conditions by stopped-flow spectroscopy. Particular effort was directed at evaluating the role of the cytochrome bs heme propionates in the interaction and electron transfer between cytochrome b₅ and c through performing each of diese three studies with a derivative of cytochrome b₅ in which die heme propionates had been esterified (referred to as DME-cytochrome b₅).
The fluorescence quenching studies on the interaction of cytochrome b₅ and porphyrin cytochrome c and die kinetics of flavin semiquinone reduction of the proteins within the cytochrome b₅ cytochrome c complex provided evidence that esterification of the cytochrome b₅ heme propionates, influences the docking geometry of the two proteins. These findings support the predictions of electrostatic calculations [Mauk, M.R., Mauk, A.G., Weber, P.C. & Matthew, J.B. (1986) Biochemistry, 25, 7085] in two respects. First, esterification of the cytochrome b₅ heme propionates detectably increases the separation between die two heme groups in die cytochrome b₅ cytochrome c complex. Second, die cytochrome c heme group is not as sterically hindered in the DME-cytochiome b₅ cytochrome c complex as in die cytochrome b₅ cytochrome c complex.
The stopped-flow studies demonstrate that the bimolecular rate constant for ferrocytochrome b₅ reduction of ferricytochrome c is determined in part by the rate of association of the two proteins. This rate of association is strongly influenced by electrostatic forces. The principal effect of esterification of the cytochrome b₅ heme propionates on the second order rate of electron transfer between cytochromes bs and c is to influence complex formation between these two proteins. The stopped-flow studies further suggest that the reduction potentials of native and DME-cytochromes b₅ are not significantly different when these proteins are bound to cytochrome c.
The nature of electron transfer protein-protein interactions and protein-protein electron transfer is discussed with respect to these findings.Medicine, Faculty of
Biochemistry and Molecular Biology, Department of
Graduate
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Dömling, Wolfgang. "Franz Liszt und B-a-c-h." Bärenreiter Verlag, 1987. https://slub.qucosa.de/id/qucosa%3A37202.
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McRostie, Bustamante Felipe. "C. B. MACPHERSON Y LA DEMOCRACIA LIBERAL." Tesis, Universidad de Chile, 2005. http://www.repositorio.uchile.cl/handle/2250/110192.
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Nie, Yong. "Functionalized nido-C 4 B 2, closo-C 2 B 5 and -C 2 B 10 carboranes, and reactivity studies on electron-poor 2,3-Dihydro-1,3-diborolyl complexes of ruthenium." [S.l. : s.n.], 2005. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11729954.
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Mazzarella, Daniele. "C-C and C-B Bond Forming Strategies Driven by the Photoexcitation of Organocatalytic Intermediates." Doctoral thesis, Universitat Rovira i Virgili, 2020. http://hdl.handle.net/10803/669808.
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El principal objectiu científic dels meus estudis de doctorat va ser demostrar que la reactivitat en estat excitat dels intermedis organocatalítics són capaços de proporcionar noves oportunitats per desenvolupar noves reaccions catalítiques mitjançant radicals per a la formació d'enllaços C-C i C-B. La fotoexcitació d'intermedis organocatalítics van proporcionar radicals mitjançant transferència d'un sol electró o homòlisis.
En el capítol II, analitzo el desenvolupament d'una funcionalització asimètrica organocatalítica fotoquímica de C-H del toluè i derivats. El nostre sistema aprofita les propietats oxidatives millorades dels ions d’imini quirals excitats amb llum visible i el caràcter bàsic dels seus contraanions per activar, a través d'una transferència d'electrons acoblada a protons multilloc, derivats de toluè. El radical resultant és atrapat més tard per l'intermedi organocatalític quiral amb alt estereocontrol.
A la segona part dels meus estudis de doctorat, em vaig concentrar en la generació catalítica de compostos fotó làbils basats en tiocarbonil per promoure la formació d'enllaços C-B i C-C. Com es detalla en el capítol III, utilitzem un organocatalitzador nucleofílic d'anió ditiocarbonil per activar electròfils d’alquil a través d'una via SN2. El producte intermedi resultant que absorbeix fotons, després de l'absorció de llum visible, genera radicals a través de l'escissió homolític de l'enllaç C-S feble. El radical generat és llavors interceptat per bis(catecolat)diboro per proporcionar productes d'èster alquilborònic. El capítol IV destaca com aquest enfocament fotolític es va expandir a l'activació dels clorurs d'acil i carbamoil a través d'una via de substitució d'acil nucleofílica. Els radicals acil i carbamoil generats fotoquímicament s'han utilitzat en reaccions de tipus Giese amb olefines pobres en electrons per formar nous enllaços C-C. Una investigació mecanística detallada, basada en anàlisis espectroscòpics i electroquímics juntament amb la caracterització d'intermedis clau, va identificar una varietat d'equilibris fora del cicle que cooperen per controlar les concentracions generals dels radicals, contribuint a l'eficiència del procés.El principal objetivo científico de mis estudios de doctorado fue demostrar que la reactividad en estado excitado de los intermedios organocatalíticos son capaces de proporcionar nuevas oportunidades para desarrollar nuevas reacciones catalíticas mediante radicales para la formación de enlaces C-C y C-B. La fotoexcitación de intermedios organocatalíticos proporcionaron radicales mediante transferencia de un solo electrón u homólisis. En el Capítulo II, analizo el desarrollo de una funcionalización asimétrica organocatalítica fotoquímica de C-H del tolueno y derivados. Nuestro sistema aprovecha las propiedades oxidativas mejoradas de los iones de iminio quirales excitados con luz visible y el carácter básico de sus contraaniones para activar, a través de una transferencia de electrones acoplada a protones multisitio, derivados de tolueno. El radical resultante es atrapado más tarde por el intermedio organocatalítico quiral con alto estereocontrol. En la segunda parte de mis estudios de doctorado, me concentré en la generación catalítica de compuestos fotolábiles basados en tiocarbonilo para promover la formación de enlaces C-B y C-C. Como se detalla en el Capítulo III, empleamos un organocatalizador nucleofílico de anión ditiocarbonilo para activar electrófilos de alquilo a través de una vía SN2. El producto intermedio resultante que absorbe fotones, tras la absorción de luz visible, genera radicales a través de la escisión homolítica del enlace C-S débil. El radical generado es entonces interceptado por bis(catecolato)diboro para proporcionar productos de éster alquilborónico. El Capítulo IV destaca cómo este enfoque fotolítico se expandió a la activación de los cloruros de acilo y carbamoilo a través de una vía de sustitución de acilo nucleofílica. Los radicales acilo y carbamoilo generados fotoquímicamente se han utilizado en reacciones de tipo Giese con olefinas pobres en electrones para formar nuevos enlaces C-C. Una investigación mecanística detallada, basada en análisis espectroscópicos y electroquímicos junto con la caracterización de intermedios clave, identificó una variedad de equilibrios fuera del ciclo que cooperan para controlar las concentraciones generales de los radicales, contribuyendo a la eficiencia del proceso.
The main scientific objective of my doctoral studies was to demonstrate that the excited-state reactivity of organocatalytic intermediates could provide new opportunities to develop novel catalytic radical C-C and C-B forming reactions. The photoexcitation of organocatalytic intermediates afforded radicals through either single-electron transfer or homolysis. In Chapter II, I discuss the development of an asymmetric organocatalytic photochemical C-H functionalization of toluene and derivatives. Our system harnesses the enhanced oxidative properties of visible-light excited chiral iminium ions and the basic character of their counteranions to activate, through a multisite proton coupled electron transfer, toluene derivatives. The ensuing radical is later trapped by the chiral organocatalytic intermediate with high stereocontrol. In the second part of my doctoral studies, I focused on the catalytic generation of photolabile thiocarbonyl-based compounds to promote the formation of C-B and C-C bonds. As detailed in Chapter III, we employed a nucleophilic dithiocarbonyl anion organocatalyst to activate alkyl electrophiles through an SN2 pathway. The ensuing photon-absorbing intermediate, upon visible light absorption, generates radicals through homolytic cleavage of the weak C-S bond. The generated radical is then intercepted by bis(catecholato)diboron to afford alkyl boronic ester products. Chapter IV highlights how this photolytic approach was expanded to the activation of acyl and carbamoyl chlorides through a nucleophilic acyl substitution pathway. The photochemically generated acyl and carbamoyl radicals have been used in Giese-type reactions with electron-poor olefins to form new C-C bonds. A detailed mechanistic investigation, based on spectroscopic and electrochemical analyses along with the characterization of key intermediates, identified a variety of off-the-cycle equilibriums that cooperate to control the overall concentrations of the radicals, contributing to the efficiency of the process.
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Radomkit, Suttipol. "New Concepts, Catalysts, and Methods for Enantioselective Synthesis of C-B and C-C Bonds." Thesis, Boston College, 2016. http://hdl.handle.net/2345/bc-ir:107272.
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Thesis advisor: Amir H. HoveydaChapter 1. Part A: N-Heterocyclic Carbenes Catalyzed Enantioselective Boryl Conjugate Additions to α,β-Unsaturated Ketones, Esters, Weinreb Amides and Aldehydes. The first broadly applicable enantioselective boryl conjugate addition reactions to a variety of α,β-unsaturated carbonyls are reported. Transformations are promoted by 5.0 mol % of a chiral Lewis basic N-heterocyclic carbene. The distinctive feature of the reactions in chemoselectivity of the method compared to the Cu-catalyzed variants has been illustrated. Part B: Enantioselective Synthesis of Boron-Substituted Quaternary Carbon Stereogenic Centers through N-Heterocyclic Carbenes Catalyzed Boryl Conjugate Additions to Cyclic and Acyclic Enones The first examples of Lewis base catalyzed enantioselective boryl conjugate additions that afford products containing boron-substituted quaternary carbon stereogenic centers are presented. The carbon–boron bond forming reactions are promoted by 1.0–5.0 mol % of a chiral N–hererocyclic carbene. Cyclic or linear α,β–unsaturated ketones can be used as suitable substrates and the desired products are obtained in 63–95% yield and 91:9 to >99:1 enantiomeric ratio. The utility of the Lewis base-catalyzed approach is demonstrated in the context of an enantioselective formal synthesis of antifungal natural product crassinervic acid. Chapter 2. Enantioselectivity Fluctuations in Phosphine–Cu-Catalyzed Enantioselective Boron-Allyl Addition to Aryl-Substituted Olefins. Catalytic enantioselective multicomponent processes involving B2(pin)2, aryl or heteroaryl monosubstituted olefins, and allylic phosphates or carbonates are disclosed. Transformations promoted by a chiral Cu–phosphine complex afford products that contain a primary C–B(pin) bond and an allyl-substituted tertiary carbon stereogenic center in up to 84% yield and 98:2 enantiomeric ratio. The utility of the approach is showcased in the enantioselective formal synthesis of biologically active heliespirones A and C. Based on mechanistic and computational studies, we show that enantioselectivities variations can depend on electronic and/or steric factors of the alkene substrate and the allyl electrophile as well as their concentration. In most cases, selectivity loss can be minimized and that the resulting insights are also applicable to reactions involving Cu–H species. Chapter 3. Synthesis of Vicinal Diboronate Compounds through Practical Phosphine–Copper Catalyzed Three-Component Processes. The phosphine–Cu-catalyzed multicomponent processes have been developed for a practical and direct synthesis of vicinal diboronate compounds. Reactions of alkenyl–boronates, allylic phosphates, and diboron reagents are promoted by 2.5–10 mol % of a Cy3P–Cu complex affording a wide range of desirable vicinal diboronate products. The ability for easy access to either regioisomers of the products with a C–B(pin) and an adjacent C–B(dan) bond that can be site-selectively functionalized is a noteworthy feature of the method
Thesis (PhD) — Boston College, 2016
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Guiban, Marie-Annick. "Etude par CVD des systèmes SI-B-C-CL-H et TI-B-C-CL-H : Caractérisation des dépots." Limoges, 1991. http://www.theses.fr/1991LIMO0126.
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Des depots des systemes si-b-c et ti-b-c ont ete elabores par depot chimique (c. V. D. ), a partir des melanges gazeux (ch#3)#4si-bcl#3-ch#4-h#2 et ticl#4-bcl#3-ch#-h#2 sous pression reduite. Ces systemes ont ete etudies respectivement par une methode de planification experimentale et par une etude parametrique theorique et experimentale. Les caracteristiques chimiques structurales et microstructurales des solides obtenus ont ete determinees. Chaque systeme donne lieu a une famille originale de materiaux en raison: -de l'existence de phases tres peu connues: (si,b)c cubique, b#4#8c#2ti#2##x quadratique; -de microstructures particulieres: materiaux tres finement divises (si-b-c, composites triphases de type dispersoide (ti-b-c). Les materiaux du syteme si-b-c recouvrent un large domaine de duretes et de modules elastiques tandis que ceux du systeme ti-b-c atteignent des duretes remarquablement elevees. Les revetements des deux familles de materiaux presentent un excellent comportement tribologique vis-a-vis du carbure de bore. Leur comportement a l'abrasion par un jet de particules s'avere cependant inferieur a celui du carbure de bore. Par contre, la resistance a l'oxydation est amelioree par rapport au carbure de bore surtout dans le cas du systeme si-b-c
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Eichenberger, Eugen. "Prinzipien und Anwendungen der Vitamin B'1'2-katalysierten elektrochemischen C-C Bindungsbildungen /." Bern, 1991. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Zhao, Tony. "Synthesis of functionalized allylic, propargylic and allenylic compounds : Selective formation of C–B, C–C, C–CF3 and C-Si bonds." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-116863.
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This thesis is focused on the development of new palladium and copper- mediated reactions for functionalization of alkenes and propargylic alcohol derivatives. The synthetic utility of the 1,2-diborylated butadienes synthesized in one of these processes has also been demonstrated. We have developed an efficient procedure for the synthesis of allenyl boronates from propargylic carbonates and acetates. This was achieved by using a bimetallic system of palladium and copper or silver as co-catalyst. The reactions were performed under mild conditions for the synthesis of a variety of allenyl boronates. Furthermore, the synthesis of 1,2-diborylated butadienes was achieved with high diastereoselectivity from propargylic epoxides. The reactivity of the 1,2-diborylated butadienes with aldehydes was studied. It was found that the initial allylboration reaction proceeds via an allenylboronate intermediate. The allenylboronate reacts readily with an additional aldehyde to construct 2-ethynylbutane-1,4-diols with moderate to high diastereoselectivity. We have also studied the copper-mediated trifluoromethylation of propargylic halides and trifluoroacetates. It was also shown that a transfer of chirality occurred when an enantioenriched starting material was used. In the last part of the thesis, we have described a method for palladium-catalyzed functionalization of allylic C-H bonds for the selective synthesis of allylic silanes. The protocol only works under highly oxidative conditions which suggest a mechanism involving high oxidation state palladium intermediates.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 1: Accepted.
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Luneau-Galy, Aurélie. "La B. B. C. Et les Français : de l'écoute à l'action, 1940-1944." Bordeaux 3, 2002. http://www.theses.fr/2002BOR30028.
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Au-delà de l'affrontement militaire, la seconde guerre mondiale inaugura un nouveau champ de bataille, celui des ondes hertziennes, où la B. B. C. Se révéla une arme redoutable et un outil de propagande privilégié face à Radio-Paris, aux mains des Allemands, et à Radio-Vichy. Au lendemain de l'armistice, alors qu'en France les médias étaient contrôlées et les sources d'information cadenacées, les autorités britanniques et le général de Gaulle, chef des Français Libres, entendirent maintenir le lien avec la population française, la tenir informée et lui insuffler l'espoir en l'avenir. Deux équipes s'attelèrent à la tâche : celle dirigée par Jacques Duchesne, sous contrôle britannique, dont le programme "Les Français parlent aux Français" devint rapidement célèbre, et celle relevant du général de Gaulle dont le porte-parole, Maurice Schumann, prit les rênes de l'émission "Honneur et patrie". Formidable instrument de guerre des mots, grâce à ses bulletins de nouvelles, ses commentaires, ses slogans, ses sketches et ritournelles, Radio-Londres s'engagea aussi dans une guerre d'action. Parallèlement au travail des mouvements de résistance, elle orchestra ponctuellement et régulièrement des manifestations civiles en France (campagne des V, 1er mai,14 juillet, 11 novembre. . . ), cherchant à coaliser les sentiments d'hostilité des Français à l'égard de l'occupant et du gouvernement de Vichy, et à inciter les compatriotes à agir au côté des Alliés. De l'écoute à l'action,la B. B. C. Fut le vecteur d'une résistance civile, le fer de lance d'une contestation populaire en vue de la libération du pays.
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Vallée, Cécile. "La b. B. C. : outil de propagande gouvernementale pendant la Seconde Guerre mondiale." Rennes 2, 1995. http://www.theses.fr/1995REN20021.
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Pendant la seconde guerre mondiale, le gouvernement britannique a transformé la BBC en outil collaborateur de manière à assurer la diffusion de sa politique de propagande sur les ondes nationales. En utilisant la persuasion et la coercition, en installant aux postes-clefs de la BBC des hommes totalement acquis à leur cause, les autorités gouvernementales ont mis en place progressivement un contrôle serré des intervenants et du contenu des émissions. Le choix politique d'un contrôle caché a permis de sauvegarder aux yeux de la population britannique et aux yeux du monde, l'image démocratique d'indépendance de la BBC. En réalité cette dernière était totalement dépendante du ministère de l'information, centralisateur et organisateur de la propagande des différents ministères. Au nom de l'intérêt national et pour protéger son image de marque, l'outil radiophonique qu'était la BBC collabora activement à la mise en place de cette propagande. Le gouvernement utilisa les ondes à sa guise pour lancer de multiples campagnes de propagande de grande envergure, touchant tous les aspects de la quotidienne, visant à contrôler, à guider, à orienter, à corriger comportements, attitudes et opinions de manière à assurer en permanence une mise en place efficace de toutes ses mesures en matière d'effort de guerre pour mener le pays à la victoire. Par des techniques de persuasion, de moralisation, d'héroïsation, de mise en valeur systématique des Britanniques, combattants sur le front intérieur, comme de ses politiques, le gouvernement tentait en permanence de soutenir le moral de la population. C'est cet impératif de soutien au moral, au coeur de la propagande, qui conduisit la BBC à présenter sur les ondes un tableau idéalisé du front intérieurDuring the Second World War, the British government transformed the BBC into a willing instrument of its propaganda. Through persuasion and pressure, by putting its own men in control of the corporation, it exercised a tight control over broadcast programmes and broadcasters. The secret nature of that control enabled both the government and the BBC to maintain the image of an independent BBC. In reality, the latter was totally dependent on the ministry of information, which centralised and planned all ministerial propaganda. In the name of national interest and in order to safeguard its image, the BBC co-operated actively with the government to put its propaganda into broadcast terms. The government used the waves freely and launched large propaganda campaigns dealing with all aspects of life on the home front. The aim was to guide and control the behaviour and attitude of the population as well as their opinions so as to ensure at all times that the war effort, as planned by the government, would be successful. Using persuasion and moralisation, constantly and repetitively stressing the qualities of the british people, the government's propaganda aimed to sustain the morale of the public. This led the BBC to broadcast an over-positive, idealised image of the home front, the listeners being encouraged to believe that they were heroes, and that it was thanks to their natural qualities of determination, of courage, and of generosity that they would win over nazism. The ideological basis of the propaganda aiming to reinforce patriotism and nationalism included essentially a continual debasement of the enemy, as well as a constant praise of the people and of a nation turned into a natural champion of all the great values of humanity
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Krummenerl, Markus. "Erfolgsfaktoren im Dialogmarketing : eine empirische Analyse unter Berücksichtigung von B-to-B- und B-to-C-Unternehmen /." Wiesbaden : Gabler, 2005. http://deposit.ddb.de/cgi-bin/dokserv?id=2668997&prov=M&dok_var=1&dok_ext=htm.
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Wu, Hao. "Catalytic Enantioselective Formations of C–B, C–C and C–Si Bonds by Organic Molecules or Transition-Metal Complexes." Thesis, Boston College, 2015. http://hdl.handle.net/2345/bc-ir:104759.
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Thesis advisor: Amir H. HoveydaCatalytic enantioselective reactions are of great importance in synthetic organic chemistry. Thus, development of efficient, selective and easily accessible catalyst for various bond formations is the main task in our laboratories. First, we have developed the first broadly applicable enantioselective boryl conjugate addition reactions to a variety of α,β-unsaturated carbonyls, promoted by a chiral Lewis basic N-heterocyclic carbene. The valuable β-boryl carbonyls were further used in complex molecule syntheses. The mechanism of these C–B bond formations was studied in details. We have also developed a practical method for enantioselective addition of an allene unit to aryl-, heteroaryl- and alkyl-substituted Boc-aldimines. These efficient C–C bond formations, catalyzed by an aminophenol-derived boron-based catalyst, were further utilized in succinct syntheses of anisomycin and epi-cytoxazone. Finally, chiral NHC–Cu complexes were employed for site-, diastereo- and enantioselective silyl conjugate additions to acyclic and cyclic dienones and dienoates. The precious enantiomerically enriched allylsilane obtained can be converted into a ketone-aldol type product, which is difficult to access through alternative methods
Thesis (PhD) — Boston College, 2015
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Mateo, Martínez Ana. "Computational studies of C-B bond formation reactions." Doctoral thesis, Universitat Rovira i Virgili, 2019. http://hdl.handle.net/10803/668479.
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La gran quantitat de fluorocarbons a la natura i la seva estabilitat a animat a la comunitat científica a trobar noves metodologies per trencar l'enllaç C-F d'aquest compostos. D'aquesta manera, aquest flurorocarbons poden ser utilitzats com a reactius a la síntesi orgànica. L'estabilitat dels fluorurs d'aril es dona per la força de l'enllaç C-F, que és l'enllaç simple més fort de la natura. Aquesta és la seva principal característica i la raó de la seva poca reactivitat. Per aquest motiu, es desafiant per la comunitat científica trobar la manera per trencar l'enllaç C-F. De la mateixa manera l'enllaç C-O te característiques molt similars a les del C-F i per això, s'ha utilitzat com a alternativa per evitar residus fluorats. Aquesta Tesi tracta de l'estudi computacional del trencament d'enllaços C-F y C-O mitjançat borilacions i catalitzades per un catalitzador de níquel. Concretament, s'ha estudiat tres reaccions diferents, les hem comparades i trobat els punts en comú de les tres reaccions.La gran cantidad de fluorocarbonos en la naturaleza y su estabilidad a animado a la comunidad científica a buscar nuevas metodologías para la rotura del enlace C-F de estos compuestos. De esta manera, estos fluorocarbonos pueden ser utilizados como reactivos en la síntesis orgánica. La estabilidad de los fluoruros de arilo se da por la fuerza del enlace C-F, que es el enlace simple más fuerte de la naturaleza. Ésta es su principal característica y la razón de su poca reactividad. Por este motivo, es desafiante para la comunidad científica encontrar la manera de romper el enlace C-F. De la misma forma el enlace C-O tiene características muy similares a las del C-F y por esto, se ha utilizado como alternativa para evitar residuos fluorados. Esta Tesis trata del estudio computacional de la ruptura de los enlaces C-F y C-O mediante borilaciones y catalizadas por un catalizador de níquel. Concretamente, se ha estudiado tres reacciones diferentes y las hemos comparado y buscado sus puntos en común.
The large presence of fluorocarbons in nature and its great stability encourage science community to found new methods to break the C-F bond of this compounds, because it could be used as a starting reactant in organic synthesis. The stability of aryl fluorides is given because its C-F bond is the strongest single bond in the nature. That is its principal characteristic and the reason of it lack of reactivity. For this reason, it is challenging for scientists found the manner for C-F cleavage. As the same wise, C-O becomes an alternative of C-F to avoid the fluoride waste. This Thesis is about the computational study of the C-F and C-O cleavage through the borylation catalysed by nickel catalyst. Concretely, we have studied three borylation of C-F and C-O bonds and we compared it and show what have in common the three reactions.
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Holm, Jonas, and Olofsson William Sörman. "Modellskattning för energianvändning inom bransch B och C." Thesis, Örebro universitet, Handelshögskolan vid Örebro Universitet, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-58383.
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Frost, James Richard. "Total syntheses of callipeltosides A, B and C." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608003.
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Minello, Anne. "Epidémiologie des hépatites chroniques virales B et C." Dijon, 2003. http://www.theses.fr/2003DIJOMU18.
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Une augmentation importante de l'incidence du cancer primitif du foie est observée en France depuis 20 ans. L'amélioration du pronostic des cirrhoses et la fréquence des hépatites B et C expliquent en partie cette augmentation. L'épidémiologie des hépatites étant mal connue en France, un registre recensant tous les cas d'AgHBs et/ou d'Ac anti-VHC diagnostiqués après janvier 1994 en Côte d'Or et janvier 1995 dans le Doubs a été créé. Les sources d'information sont les biologistes, les hépatogastroentérologues, infectiologues, internistes, et les anatomopathologistes. L'étude d'après une année de fonctionnement a objectivé des taux de détection annuels d'Ac anti-VHC de 26,4 ± 4,6 et d'AgHBs de 12,9 ± 2,6/100 000 habitants. Deux pics de taux spécifiques d'Ac anti-VHC (25-44 et 55-75 ans) et un seul d'AgHBS (15-44 ans) étaient objectivés. Cette étude a testé avec succès la faisabilité d'un tel registre. Les études sur les années 1994-1997 ont permis : 1) de confirmer que les résultats des séries hospitalières ne pouvaient être extrapolés à la population générale, 2) d'objectiver la place importante du médecin généraliste dans le diagnostic de l'hépatite C, 3) de constater que les patients sans facteur de risque identifié avaient des caractéristiques virologiques identiques aux patients contaminés par voie nosocomiale. Malgré une bonne efficacité du traitement, 16% des patients avec hépatie C n'ont bénéficié d'aucune prise en charge sur la période 1994-1999. L'étude des tendances évolutives des taux de détection de l'AgHBs a objectivé une diminution régulière de 1994 à 1999, excepté chez les patients ayant échappé à la vaccination. Ce registre des hépatites virales B et C est un système des surveillance permettant de connaître les modalités de prise en charge des malades, les tendances évolutives de ces épidémies, l'efficacité des mesures sanitaires prises. Il précisera la part des hépatites B et C dans l'augmentation d'incidence des cancers primitifs du foie.
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LAHRECH, MOHAMED. "Etudes cristallochimiques du systeme ternaire : la-b-c." Rennes 1, 1990. http://www.theses.fr/1990REN10146.
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Nous avons etudie le systeme ternaire la-b-c par les methodes de radiocristallographie et de metallurgie. En plus des composes deja connus tels que: lab#6, lab#4, b#4c, lac#2, la#2c#3, lab#2c#2 et la#5b#2c#6, dont nous confirmons l'existence et precisons les solubilites mutuelles. Nous avons decouvert quatre phases ternaires: la#1#0b#9c#6, la#1#0b#9c#1#2, la#1#5b#1#4c#1#9, lab#2c#4 plus une phase binaire de composition tres proche de lac#6. Le compose lac#6 presente une structure plus compliquee que les autres phases (smc#6, cac#6, etc. . . ) d'intercalations. Son existence est neanmoins confirmee: 1) pour les deux composes: lab#2c#4 et la#1#0b#9c#6, nous proposons l'indexation de la maille elementaire; 2) la structure cristalline de la#1#0b#9c#1#2, etait etablie par analogie avec celle de ce#1#0b#9c#1#2, les deux phases sont isotypes; 3) une etude complete sur monocristal nous a permis de determiner la structure de la phase monoclinique, la#1#5b#1#4c#1#9. Cette phase est apparemment unique dans la serie des terres-rares, car les elements les plus legers (ce, pr, etc. . . ) ne forment pas ce compose; 4) finalement, nous presentons une projection polytherme du diagramme ternaire avec les equilibres des phases entre elles, proche de leurs points de fusion
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Ivashchenko, V. I., P. L. Scrynskyy, A. I. Kuzmichev, L. A. Ivashchenko, O. Yu Khyzhun, I. I. Timofejeva, O. O. Butenko, and V. M. Granko. "Characterization of Ti-B-C-N Nanocomposite Coatings." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35053.
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Nanocomposite Ti-B-N-C coatings were deposited by magnetron sputtering of TiN and B4C targets in the argon-nitrogen atmosphere at different nitrogen flow rates (FN2). The structure, chemical bonding and mechanical properties were investigated. The results of the investigations of the nanocomposite, TiN and BCN coatings show that the Ti-B-C-N coatings consist of the TiNC nanocrystals (3.4 – 6.5 nm) embedded into the amorphous matrix that consists of amorphous boron nitrogen (a-BN) and amorphous carbon (a-C). The coatings contain a small admixture of titanium oxides that are aggregated at the grain boundaries. The coatings deposited at high nitrogen flow rates were textured. An introduction of nitrogen prompts the formation of the nanocrystallites of the TiN-TiC solid solutions and the a-BN amorphous tissue, which, in turn, causes the improvement of the mechanical properties of the Ti-B-C-N coatings. The best samples ex-hibited nanohardnes above 39 GPa.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35053
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Ziegler, Andreas. "Neue Organoborane aus C 2 B 2 -Bausteinen." [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9142812.
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Hoyer, Frank. "Strukturaufklärung des C-19-C-29-Fragmentes von Amycin B sowie von Sibyllimycin." [S.l. : s.n.], 1998. http://deposit.ddb.de/cgi-bin/dokserv?idn=954824806.
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Cassen, Audrey. "Pilotage à distance de l'activation de liaisons B-H, C-H et B-C dans des boranes polyfonctionnels : synthèse de complexes agostiques sigma-B-H et borohydrures." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2533/.
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Les travaux présentés ici s'inscrivent dans le cadre de l'activation de la liaison s-B-H par des complexes de ruthénium. Ils concernent l'étude du mode de coordination de composés boranes bifonctionnels de type L~BHR, au sein desquels L est une base de Lewis et R, un substituant sur l'atome de bore. Ces travaux ont pour objectif de montrer que le mode de coordination de ces composés est directement influencé par la base de Lewis utilisée ainsi que par la nature de l'espaceur présent entre la base de Lewis et le motif boré, en s'appuyant sur une étude préliminaire réalisée précédemment dans l'équipe. Dans cette optique, la famille des ligands phosphinoboranes de type P~BH(NiPr2) a été étendue et plusieurs espaceurs ont été considérés. La réactivité des composés à espaceur phénylméthylène, méthylphénylène et naphtylène vis-à-vis du précurseur [RuH2(. 2-H2)2(PCy3)2] a été étudiée en détail. Un quatrième composé de type phosphinoborane ne comportant pas d'espaceur et dans lequel les atomes de phosphore et de bore sont directement connectés a aussi été synthétisé et son comportement vis-à-vis du ruthénium a pu être mis en évidence. L'étude "miroir" des ligands phosphinoboranes à espaceur phénylméthylène et méthylphénylène démontre qu'une simple inversion des groupements fonctionnels phosphino et boryle au sein du ligand mène à un mode de coordination de ce dernier complètement différent. Dans un second temps, l'influence de la base de Lewis sur le mode de coordination du ligand a été mise en évidence par deux approches synthétiques différentes grâce à la complexation de boranes soufrés de type S~BH(NiPr2). La combinaison de plusieurs techniques complémentaires telles que la résonance magnétique nucléaire multinoyaux et à température variable, la diffraction des rayons X ainsi que les calculs théoriques m'a ainsi permis de définir finement les interactions mises en jeu entre le ligand et le fragment métallique et de mettre en évidence des modes de coordination inéditsIn line with the general problem of the activation of B-H s bonds, this work is directly related to the study of the coordination mode of potentially bidentate ligands L~BHR, in which L is a Lewis base and R, a boron substituent. Herein, we show that the nature of the spacer linking the Lewis base and the sp² hybridized boron atom and the nature of the Lewis base itself can have a dramatic impact on the coordination mode of the ligand to the ruthenium center. Thus, based on a preliminary study made by our group, the family of phosphinoborane compounds P~BH(NiPr2) have been extended and several spacers have been considered. The coordination of phenylmethylene, methylphenylene and naphtylene spacer containing ligands to [RuH2(. 2-H2)2(PCy3)2] has been meticulously studied as well as a fourth phosphinoborane ligand featuring no spacer between the phosphino and boryl functions. Considering phenylmethylene and methylphenylene ligands, which result from the swapping of the phosphino and boryl groups, new and original coordination modes have been evidenced. Furthermore, the influence of the Lewis base was evaluated by two different synthetic approaches thanks to the complexation of sulfidoboranes S~BH(NiPr2) to ruthenium. The combination of several techniques as nuclear magnetic resonance, X ray diffraction and theoretical calculation allowed us to clearly define the interactions between the ligand and the metal and to highlight new coordination modes
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Neal, Richard J. "The loosely-bound proton in ¹³N and the transfer reaction ¹¹B(¹³N,¹²C)¹²C." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/1783.
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The radioactive nucleus ¹³N (t½ = 10 min, Jπ = ½) contains one loosely bound proton (Sp = 1.94 MeV) which can be considered to be bound to a core of ¹²C. Taking advantage of the recent availability of beams of radioactive nuclei at Louvain-la-Neuve, Belgium, a beam of ¹³N has been used to investigate the transfer reaction ¹¹B(¹³N,¹²C)¹²C. Particle-γ coincidence data was taken, using the LEDA silicon strip array and BaF₂ modules, gating on the 15.11 MeV γ-decay from the T = 1 state in ¹²C*. Two final states, corresponding to ¹²Cgs + ¹²C*(15.11 MeV) and ¹²C*(4.44 MeV)+ ¹²C*(15.11 MeV) have been observed and angular distributions have been measured for both transitions at each of two beam energies, 29.5 MeV and 45 MeV. The results are discussed with special reference to the loosely bound nature of the valence proton in ¹³N; the transfer reaction has been modelled using a DWBA code, with the ¹³N ground state constructed as a mixture of states: a p½ proton bound to ¹²Cgs , or a p3/2 proton bound to ¹²C*₂₊ (4.44 MeV). Fits to the experimental data have been obtained using a very shallow set of optical potentials, which are found to be energy dependent. The agreement with experiment is good, with the exception of the ¹²C*(4.44)+¹²C*(15.11) transition at the lower beam energy, which is significantly underestimated by the calculations, suggesting a contribution from a different reaction mechanism.
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Sturzenegger, Erich Oscar. "Entwicklung von Enzymimmunoassays zur quantitativen Bestimmung der Apoliproteine B, C-I und C-III /." [S.l : s.n.], 1985. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Burgermeister, Serge. "Inbound-B-to-C-Marketing für Unternehmen der Telekommunikationsbranche." St. Gallen, 2009. http://www.biblio.unisg.ch/org/biblio/edoc.nsf/wwwDisplayIdentifier/02604858002/$FILE/02604858002.pdf.
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Sentjens, Roel Emiel Johannus Henricus. "New developments in hepatitis B, C and G virus." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2003. http://dare.uva.nl/document/87188.
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Raimondas, Kreivaitis. "Fe-C-Cr-B lydinių atsparumo abrazyviniam dilimui tyrimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2007. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2007~D_20070816_154703-67221.
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Darbe analizuojamas abrazyvinio dilimo mechanizmas. Nustatomi šiems procesams didžiausią įtaką turintys veiksniai. Analizuojama abrazyvinių dalelių formos ir jų abrazyvumo vertinimo metodika. Apžvelgiami abrazyvinio dilimo modeliai. Abrazyvinių dalelių veikiami darbinių dalių paviršiai intensyviai dyla, todėl atsižvelgiant į jų darbo sąlygas būtina tinkamai parinkti jų savybes – kietumą, stiprumą bei sudėtį (legiravimą). Šių paviršių atnaujinimui ir sustiprinimui dažnai racionalu naudoti įvairios sudėties apvirinamus sluoksnius. Šio darbo tikslas – ištirti apvirintų kietųjų sluoksnių abrazyvinio dilimo ypatybes. Taip pat, ištirti lydinių abrazyvinio dilimo įtaką dylančio paviršiaus mikrogeometriniams parametrams. Atliktais tyrimais nustatyta legiruojančių elementų įtaka apvirintų sluoksnių abrazyviniam dilimui. Nustatyta optimali apvirinto sluoksnio sudėtis abrazyvinio dilimo sumažinimui. Tai pat nustatyta, kad termiškai apdirbtų plienų ir apvirintų sluoksnių dilimo atvejais nudilimas turi ryšį su paviršiaus parametru SPQP. Tuo remiantis, matuojant paviršiaus profilį, galima prognozuoti nudilimo dydį.There is analysis of abrasive wear mechanism in this work. The most important factors in these processes were established. There are analysed technique of abrasive particles properties and abrasive wear models. Surfaces witch are under the abrasive sway wear very fast. Considering to working conditions of these surfaces it is necessarily to choose there properties – hardness, strength and composition. For renovation and fortify of these surfaces it is often rational hard facing. The aim of this work was to estimate the influence of alloying elements content to abrasive wear. And estimate the abrasive wear influence to micro geometry of wearing surface. The influence of alloying elements to abrasive wear was estimated. To decrease abrasive wear the optimal chromium content in the arc welded alloy was investigated. Clear influence of heat treated steels and arc welded alloys abrasive wear on surface profile quality parameter SPQP is estimated. Considering with that we can measure surface profile and predict the wear rates.
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Doran, John. "Is toilet training as easy as A B C?" Thesis, University of Plymouth, 1997. http://hdl.handle.net/10026.1/2465.
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Toilet training is often viewed as a fairly straightforward process. This may be why much of the prescriptive literature available today has not been subject to empirical investigation. This study followed twenty-six children through toilet training to investigate five factors that are assumed to be associated with a successful outcome to training - child readiness, parental readiness, behavioural style of parents, child temperament and the type of approach parent's use to train their child. Three of these five factors - behavioural style of parent's, child temperament and the approach parent's use to train their child - were found to be associated with a successful outcome. Advice for parent's who have difficulties with toilet training is presented along with recommendations for improving the measures used in this study for future research.
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Oni, Oluropo Ayodele. "Genotypes of hepatitis B and C viruses in Nigeria." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243523.
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Douville, Guillaume. "Déploiements de carquois valués de types B et C." Mémoire, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/8013.
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Dans ce mémoire, après avoir défini le concept de déploiement, nous obtenons les variables des algèbres amassées et les classes de mutations associées aux carquois valués de types B et C en ramenant l'étude de ces concepts à celle des familles A et D, respectivement.
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Ejjoummany, Abdelaziz. "Design et fonctionnalisation d’hétérocycles originaux de type bicycliques [5-5] et tricycliques [6-5-6] à visée thérapeutique potentielle." Thesis, Orléans, 2020. http://www.theses.fr/2020ORLE3141.
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L’accès à de nouveaux composés hétérocycliques originaux biologiquement actifs, constitue l’un des principaux objectifs de notre groupe de recherche. Dans ce contexte, les travaux de cette thèse ont pour but principal, la conception de trois nouvelles familles de composés hétérocycliques contenant un motif pyrazolique susceptibles de présenter des activités biologiques, à savoir les pyrido[1',2':1,5]pyrazolo[4,3-d]pyrimidine, les pyrrolo[3,4-c]pyrazoles et les pyrazolo[5,1-b]thiazoles. Ce manuscrit est essentiellement dédié à un travail de méthodologie décrivant les différentes voies d’accès à ces hétérocycles originaux, tricycliques et bicycliques potentiellement modulables. La réactivité de ces synthons clés est ensuite étudiée avec divers procédés de fonctionnalisation palladocatalysés (Activation au PyBrOP-(hétéro)arylation, Liebeskind-Srogl, Suzuki-Miyaura, Buchwald-Hartwig, C-H arylation, substitution nucléophile aromatique) pour élaborer d’intéressantes chimiothèques construites autour de ces structures inédites, ouvrant ainsi de nombreuses perspectives pharmacologiquesThe access to new original biologically active heterocyclic compounds, is one of the main objectives of our research group. In this context, the main purpose of this thesis is the design of three new families of heterocyclic compounds containing a pyrazolic motif that may exhibit biological activities, namely pyrido[1',2': 1.5]pyrazolo[4,3-d]pyrimidine, pyrrolo[3,4-c]pyrazole and pyrazolo[5,1-b]thiazole.This manuscript is essentially dedicated to a methodology work describing the different routes of access to these originals and potentially modular tricyclic and bicyclic precursors. The reactivity of these key synthons is then studied towards aromatic nucleophilic substitutions reactions and various pallado-catalyzed methods of functionalization (Activation with PyBrOP- (hetero) arylation, Liebeskind-Srogl, Suzuki-Miyaura, Buchwald-Hartwig, C-H arylation, aromatic nucleophilic substitution) to develop interesting libraries built around these unusual structures, thus opening numerous pharmacological perspectives
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Johansson, Anders. "Kommunikationsgränssnitt mot GP&C transponder." Thesis, Linköping University, Department of Science and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1591.
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Examensarbetet som beskrivs i denna rapport handlar om en ny teknik för att förbättra säkerheten för flygplan i luften och i närheten av flygplatser. Denna teknik benämns ADS-B (Automatic Dependent Surveillance Broadcast), och är tänkt att göra det möjligt för piloter att själva få information om trafik i närområdet. Nuvarande system baserar sig i huvudsak på visuella observationer från flygledare i kontrolltorn samt radarspaning omkring flygplatserna. Med det nuvarande systemet kommer det att bli både dyrt och svårt att upprätthålla en acceptabel nivå på flygsäkerheten när trafiken ökar.
Arbetet har bedrivits i AerotechTelubs regi i Linköping samt med hjälp ifrån företaget Sectra Wireless Technologies AB. Huvuddelen av arbetet inriktar sig på implementerandet av C-funktioner för att hantera kommunikationen och sammankopplandet av ett tidigare skapat system, för grafikvisning, med en transponder som hanterar ADS-B (tillverkad av Sectra). Målet med detta var att göra förberedande arbete åt AerotechTelub som de förhoppningsvis kommer att kunna använda i ett eventuellt kommande projekt. Rapporten tar upp några standarder som hör till konceptet GP&C (Global Positioning & Communication), samt beskriver de delar som ligger till grund för programmets funktion.
Examensarbetet har resulterat i ett demonstrationsprogram för att visa hur en lösning av problemet kan se ut. Det har tyvärr inte gått att säkerställa om programmet fungerar till fullo, men genom simuleringar och andra tester har huvuddelen av programmets funktioner gått att verifiera.
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Kapp, Felix, and Hermann Körndle. "Was lerne ich aus einer Lernaufgabe? a) gar nichts, b) Faktenwissen, c) etwas über meine Lernstrategien, d) Antwort b und c sind richtig." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-76302.
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Interaktive Lernaufgaben stellen eine Möglichkeit dar, das Lernen und den Lernerfolg mit digitalisierten Lehrmaterialien durch interaktive Elemente zu unterstützen. In einer Vielzahl von Learning-Management-Systemen gehört die technische Möglichkeit solche Aufgaben zu erstellen bereits zum Standard-Repertoire. Dieser Beitrag thematisiert anhand von drei empirischen Studien, welchen psychologischen Kriterien interaktive Lernaufgaben genügen sollten, um einen erfolgreichen Wissenserwerb zu fördern. Dabei wird aufgezeigt, dass Lernaufgaben, die unter Beachtung psychologischer Konstruktionsregeln erzeugt wurden, die Lernenden nicht nur beim Erwerb von Faktenwissen unterstützen, sondern ihnen beim selbstregulierten Lernen auch Rückmeldung über die von ihnen eingesetzten und einzusetzenden Lernstrategien geben.
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Rogge, Torben. "Experimental and Computational Studies on Ruthenium- and Manganese-Catalyzed C-H and C-C Activation." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://hdl.handle.net/21.11130/00-1735-0000-0005-1298-B.
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Boyes, A. L. "Synthesis of the talaromycins A, B, C and E and synthetic studies towards ephedrine C." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233899.
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