979 resultados para Steel-concrete bonding
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The description reads "(1) General view of the Falls from the New Steel Bridge - 'Maid of the Mist' at landing - Niagara, U.S.A.". The reverse reads similar "General view from Suspension Bridge, Niagara Falls, U.S.A.".
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The description of the image reads "(4)-8972-General view of Falls from new steel bridge - Maid of the Mist at landing - Niagara, U.S.A." The reverse of the image includes the description, "We are standing on the new steel bridge over Niagara River, 190 feet above the water and looking a little west of south, up the river towards Lake Erie. The high cliff at the extreme left, on the American side, is Prospect Point, where a crowd is gathered at this moment to view the Falls that we see just beyond Prospect Point. That dark, tree-covered mass of rock beyond is Goat Island; and just this side of Goat Island we see a bit of its precipice has been cut off separate from the rest by the powerful current of the waters - the smaller portion is Luna Island, and the Luna Falls go pouring down between the two islands. The face of the precipice curves inward beneath the Luna Falls leaving behind the 160 foot sheet of water the unearthly hollow known as the Cave of the Winds. Beyond Goat Island we see the gigantic curve of the Horseshoe Falls, 3,010 feet long and 158 feet high, reaching around through the clouds of spray to the farther Canadian shore. (The boundary line between British and American territory is in mid-stream.) It has been estimated that every minute 375,000 tons of water pour over these Horseshoe Falls, and they are wearing away the cliffs, moving back up the stream at the rate of 2.4 feet per year. It was probably only about a thousand years ago that they took their plunge just about where we stand now. Down there below us, at the wharf is the Maid of the Mist at the American landing taking on passengers who have come down the steep bank by the inclined railway. Its course takes it through those clouds of spray almost to the very foot of both Falls, - waters falling from 167 feet overhead, and water surging at least as many feet deep under the staunch little vessel. See special 'keyed' maps of Niagara pub. by Underwood and Underwood, also the Niagara Book by Mark Twain, W.D. Howells and others."
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As a major manufacturing hub in southern Ontario, Hamilton enjoyed considerable economic stability during the twentieth century. However, like most industrial-based cities, Hamilton’s role as a North American manufacturing producer has faded since the 1970’s. This has resulted in dramatic socio-economic impacts, most of which are centered on the inner city. There have been many attempts to revive the core. This includes Hamilton’s most recent urban renewal plans, based upon the principles of Richard Florida’s creative city hypothesis and Ontario’s Places to Grow Act (2005). Common throughout all of Hamilton’s urban renewal initiatives has been the role of the local press. In this thesis I conduct a discourse analysis of media based knowledge production. I show that the local press reproduces creative city discourses as local truths to substantiate and validate a revanchist political agenda. By choosing to celebrate the creative class culture, the local press fails to question its repercussions
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Indenture of assignment of mortgage between Jacob Thomas Nottle, land agent of Hamilton and George Steel of the Village of Romoka in the County of Middlesex regarding a parcel of land in the village of Romoka composed of Lot no. 17 in Block U. Robert Telfer granted to Ira Spalding these lands and premises subject to payment of principal money and interest (2 copies), June 18, 1874.
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The exact mechanistic understanding of various organocatalytic systems in asymmetric reactions such as Henry and aza-Henry transformations is important for developing and designing new synthetic organocatalysts. The focus of this dissertation will be on the use of density functional theory (DFT) for studying the asymmetric aza-Henry reaction. The first part of the thesis is a detailed mechanistic investigation of a poorly understood chiral bis(amidine) (BAM) Brønsted acid catalyzed aza-Henry reaction between nitromethane and N-Boc phenylaldimine. The catalyst, in addition to acting as a Brønsted base, serves to simultaneously activate both the electrophile and the nucleophile through dual H-bonding during C-C bond formation and is thus essential for both reaction rate and selectivity. Analysis of the H-bonding interactions revealed that there was a strong preference for the formation of a homonuclear positive charge-assisted H-bond, which in turn governed the relative orientation of substrate binding. Attracted by this well-defined mechanistic investigation, the other important aspect of my PhD research addressed a detailed theoretical analysis accounting for the observed selectivity in diastereoselective versions of this reaction. A detailed inspection of the stereodetermining C-C bond forming transition states for monoalkylated nitronate addition to a range of electronically different aldimines, revealed that the origins of stereoselectivity were controlled by a delicate balance of different factors such as steric, orbital interactions, and the extent of distortion in the catalyst and substrates. The structural analysis of different substituted transition states established an interesting dependency on matching the shape and size of the catalyst (host molecule) and substrates (guest molecules) upon binding, both being key factors governing selectivity, in essence, offering an analogy to positive cooperative binding effect of catalytic enzymes and substrates in Nature. In addition, both intra-molecular (intra-host) and inter-molecular (host-guest, guest-guest) stabilizing interactions play a key role to the high π-facial selectivity. The application of dispersion-corrected functionals (i.e., ωB97X-D and B3LYP-D3) was essential for accurately modeling these stabilizing interactions, indicating the importance of dispersion effects in enantioselectivity. As a brief prelude to more extensive future studies, the influence of a triflate counterion on both reactivity and selectivity in this reaction was also addressed.
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Letter to S.D. Woodruff from A. Jeffrey importer of Hardware, Iron, Steel, and Window Glass of St. Catharines, Ont. A. Jeffrey says that he will be able to supply Mr. Woodruff with glass and iron pipe, June 7, 1875.
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Letter to S.D. Woodruff from A. Jeffrey importer of Hardware, Iron, Steel, and Window Glass of St. Catharines, Ont. regarding breakage and freight, June 23, 1875.
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Receipt from A. Jeffrey importer of Hardware, Iron, Steel, Nails and etc. regarding payment received on glass panes, Nov. 12, 1875.
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UANL
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UANL
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UANL
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Rapport de recherche
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Je reconnais l’aide financière du Centre d’études ethniques des Universités montréalaises (CEETUM), du Ministère de l’Éducation – Aide Financières au Études (AFE), et ainsi que de l’Université de Montréal (Département de psychologie et Faculté des études supérieures) dans la réalisation de ce mémoire.
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Introduction : La force d’adhésion à l'interface métal-céramique avec les résines auto-polymérisantes destinées au collage indirect des boîtiers orthodontiques n'a pas été évaluée à ce jour et un protocole clinique basé sur la littérature scientifique est inexistant. Objectifs : 1) Comparer la force de cisaillement maximale entre des boîtiers métalliques et des surfaces en porcelaine préparées selon différentes méthodes; 2) Suggérer un protocole clinique efficace et prévisible. Matériel et méthodes : Quatre-vingt-dix disques en leucite (6 groupes; n = 15/groupe) ont été préparés selon 6 combinaisons de traitements de surface : mécaniques (+ / - fraisage pour créer les rugosités) et chimiques (acide fluorhydrique, apprêt, silane). Des bases en résine composite Transbond XT (3M Unitek, Monrovia, California) faites sur mesure ont été collées avec le système de résine adhésive auto-polymérisante Sondhi A + B Rapid Set (3M Unitek, Monrovia, California). Les échantillons ont été préservés (H2O/24hrs), thermocyclés (500 cycles) et testés en cisaillement (Instron, Norwood, Massachusetts). Des mesures d’Index d’adhésif résiduel (IAR) ont été compilées. Des tests ANOVAs ont été réalisés sur les rangs étant donné que les données suivaient une distribution anormale et ont été ajustés selon Tukey. Un Kruskall-Wallis, U-Mann Whitney par comparaison pairée et une analyse de Weibull ont aussi été réalisés. Résultats : Les médianes des groupes varient entre 17.0 MPa (- fraisage + acide fluorhydrique) à 26.7 MPa (- fraisage + acide fluorhydrique + silane). Le fraisage en surface ne semble pas affecter l’adhésion. La combinaison chimique (- fraisage + silane + apprêt) a démontré des forces de cisaillement significativement plus élevées que le traitement avec (- fraisage + acide fluorhydrique), p<0,05, tout en possédant des forces similaires au protocole typiquement suggéré à l’acide fluorhydrique suivi d’une application de silane, l’équivalence de (- fraisage + acide fluorhydrique + silane). Les mesures d’IAR sont significativement plus basses dans le groupe (- fraisage + acide fluorhydrique) en comparaison avec celles des 5 autres groupes, avec p<0,05. Malheureusement, ces 5 groupes ont des taux de fracture élévés de 80 à 100% suite à la décimentation des boîtiers. Conclusion : Toutes les combinaisons de traitement de surface testées offrent une force d’adhésion cliniquement suffisante pour accomplir les mouvements dentaires en orthodontie. Une application de silane suivie d’un apprêt est forte intéressante, car elle est simple à appliquer cliniquement tout en permettant une excellente adhésion. Il faut cependant avertir les patients qu’il y a un risque de fracture des restorations en céramique lorsque vient le moment d’enlever les broches. Si la priorité est de diminuer le risque d’endommager la porcelaine, un mordançage seul à l’acide hydrofluorique sera suffisant.