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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
531

Direct Comparison of P-Selectin Glycoprotein Ligand-1 and Sialyl Lewis X Adhesion

Zou, Xiaoyan 29 December 2008 (has links)
No description available.
532

Applied Molecular Recognition of HECA-452 and Wnt5a in Pathological Inflammation

Kummitha, China Malakondaiah 16 April 2010 (has links)
No description available.
533

“How Can They Meet Us Face to Face?”: The Faith-Reason Debate in C. S. Lewis’s <i>Till We Have Faces</i> and Medieval Dream Visions

Wagner, Erin K. 05 August 2010 (has links)
No description available.
534

Att använda bilderboken som en lättläst version av kapitelboken : – en komparativ adaptionsanalys av en kapitelbok och bilderbok.

Duty, Sophie January 2022 (has links)
Sophie Duty: Att använda bilderboken som en lättläst version av kapitelboken - en komparativ adaptionsanalys av en kapitelbok och bilderbok om Alice i Underlandet av Lewis Carroll (2022). Svenska, självständigt arbete avancerad nivå, 15 högskolepoäng. Örebro universitet, institutionen för humaniora, utbildnings- och samhällsvetenskap. Syftet med denna studie är att undersöka om det är det lämpligt att använd sig av bilderboken som en lättläst version av kapitelboken i undervisningen för åk f-3 och vilka möjligheter och utmaningar det i så fall finns. För att undersöka detta har en komparativ adaptions analys med både en kvalitativ och kvantitativ metod genomförts. Jag har jämfört kapitelboken Alice i underlandet (2016) med bilderboken Alice i Underlandet (2015) genom att titta på skillnader i deras intriger, handlingens komposition och hur de använder av bilder som stöd. Analysen visar att trots att det finns skillnader i verkens episoder så är intrigerna lika varandra. Den stora skillnaden som funnits är i hur handlingarnas komponerats och om användningen av bilder som stöd för texten skiljer sig i de olika böckerna? I så fall hur? Avslutningsvis har dessa resultat använts i en didaktisk diskussion kring bilderbokens lämplighet att användas som en lättläst version av kapitelboken i undervisningen för åk f-3 och vilka möjligheter och utmaningar finns det i så fall
535

Mechanism and application of Lewis and Brønsted acid effects in organotransition metal catalysis

Becica, Joseph January 2019 (has links)
The essential questions of the dissertation research described here address concepts in homogeneous catalysis and organometallic chemistry, with a focus on method development for catalytic reaction applications in organic synthesis. The unifying theme throughout the research is the development of rational design principles for cooperative catalysis through both mechanistic and empirical study. Cooperative catalysis – in which multiple catalysts enable increased activity or selectivity versus a single catalyst system – can involve some combination of a transition metal, Lewis acid, and Brønsted acid. Chapter 1 reviews the literature regarding the cooperativity of transition metal and Lewis acid catalysis, and discusses four main areas in organic synthesis and the facilitation of these trnasformations by Lewis acids: (a) C-C bond and C-H activation, (b) hydrogenolysis of carboxylic acid derivates and ethers, (c) Au catalyzed alkyne activation and cyclization reactions, and related reactions, and (d) Pd catalyzed C-C and C-N bond forming reactions. These different topics are selected based on the mechanistic insight provided into the nature of transition metal-Lewis acid cooperativity. Chapter 2 describes the observation of Lewis acid acceleration of a Pd catalyzed C-N bond coupling. The synthetic methodology is elaborated using metal triflates as cocatalysts, and Lewis acid acceleration is observed for a variety of different N-nucleophiles. Qualitative mechanistic study implicates the role of halide anions in inhibiting this catalytic reaction, and it is proposed that metal triflates are competent to accelerate catalysis by binding halide anions, and therefore attenuating halide inhibition. This hypothesis is supported by initial rate measurements and 31P NMR experiments. Rationalizing trends observed in the reactivity of Lewis acids in the cooperative reactions described in Chapters 1 and 2 is challenging. Therefore, our goal was to provide further insight into the behavior or Lewis acids in complex reaction settings. Inspired by 31P NMR experiments from Chapter 2, a next generation NMR probe to observe anion exchange reactions of metal triflate Lewis acids is developed. Metal-ligand titrations are performed for a variety of metal triflates with complexes of the type (POCOP)Pd(X) (X = Cl, Br, I, OAc) to observe a variety of different X anion affinities for metal triflates. The determined parameters are discussed within the context of Lewis acid catalyzed reactions, along with other Lewis acidity parameters, such as hydrolysis constants and effective charge density. The data suggest that the chloride and iodide anion affinities of a Lewis acid represent a continuum of π-acidity (high anion affinity) and propensity to dissociate into cationic Mz+ species (low anion affinity). The anion affinities do not correlate with the tendency of a metal salt to release Brønsted acids or their respective effective charge densities. Based on the insight into Lewis acidity from Chapters 1 and 3, the parallel between Brønsted and Lewis acids is realized, and the role of both Brønsted and Lewis acids in mediating organic reactions is often related. In Chapter 4, further questions into the cooperativity of π-acids and Brønsted acids is explored. It is demonstrated that selectivity of alkene isomerization can be controlled through a cooperative system. A series of Mo(0) complexes are prepared and explored in their ability to mediate the conversion of terminal alkenes to internal alkenes, and the reaction is found to be promoted by Brønsted acid (TsOH) cocatalyst. Rational design principles are developed to maximize selectivity for (Z)-2-alkenes in this catalyst system. It is proposed that TsOH acts to generate a catalytic MoH species which mediates catalysis, and the role of phosphine ligands is critical in inhibiting the formation of less selective isomerization catalysts. Chapter 5 and 6 entail further method development for catalytic reactions based on the mechanistic wisdom described in previous chapters. High throughput experimentation is employed to rapidly assess conceptual aspects of Pd catalysis, such as ligand and additive effects, and facilitate catalyst discovery and optimization. Based on the substrate scope performed in Chapter 2, it was realized there is a knowledge gap in the ability to synthesize tertiary sulfonamides, both in terms of conventional methods, or modern Pd-catalyzed methods. A significant advance in organic reaction methodology is described: a new Pd catalyst featuring the AdBippyPhos ligand is discovered to be apt for the coupling of secondary sulfonamides with heteroaryl halides to yield tertiary N-heteroarylhalides. Using high throughput experimentation, 24 diverse heterocycles are screened with 12 sulfonamide variants to prepare &gt;100 new products on microscale. Computational modelling reveals the unique steric parameters of the AdBippyPhos ligand, and a mechanistic rationale for its success in catalysis is provided. Lastly, Chapter 6 describes the use of a LiOTf additive to control the selectivity of Pd-catalyzed C-C bond forming reactions. In the presence of LiOTf, a Mizoroki-Heck type reaction, the alkenylation of an aryl halide with a vinyl ether, proceeds with regioselectivity. In the absence of LiOTf, a solvent (CH3CN) activation pathway proceeds to give benzyl nitrile products. High throughput microscale reactions discovered that the Pd/xantphos catalyst is uniquely selective to provide branched styrenes when using the Cs2CO3/CH3CN base/solvent combination. However, reaction performance differed on large scale reactions, where LiOTf was necessary to observe the Mizoroki-Heck reaction pathway. Mechanistic study, in the form of kinetic experiments and 31P NMR experiments, focused on the role of LiOTf in affecting chemoselectivity. It is proposed that xantphos oxidation is responsible for mediating the Mizoroki-Heck reaction pathway, whereas in the absence of xantphos oxidation, CH3CN α-arylation ensues. Due to the insoluble nature of the catalyst materials, xantphos oxidation is ordinarily slow under anaerobic conditions due to mass transfer limitation. LiOTf generates a soluble [(xantphos)Pd(NCCH3)2][OTf]2 and potentially mediates the formation of xantphos-monoxide catalyst which is competent for alkenylation. / Chemistry
536

The Coordination Chemistry of Xenon Trioxide with Oxygen Bases

Marczenko, Katherine January 2018 (has links)
This thesis extends our fundamental knowledge in the area of high oxidation state chemistry of xenon trioxide, XeO3. Oxygen coordination to the Xe(VI) atom of XeO3 was observed in its adducts with triphenylphosphine oxide, [(C6H5)3PO]2XeO3, dimethylsulfoxide, [(CH3)2SO]3(XeO3)2, pyridine-N-oxide, (C5H5NO)3(XeO3)2, and acetone, [(CH3)2CO]3XeO3. The crystalline adducts were characterized by low-temperature single-crystal X-ray diffraction and Raman spectroscopy. Unlike solid XeO3, which detonates when mechanically or thermally shocked, the solid [(C6H5)3PO]2XeO3, [(CH3)2SO]3(XeO3)2, and (C5H5NO)3(XeO3)2 adducts are insensitive to mechanical shock, but undergo deflagration when exposed to a flame. Both [(C6H5)3PO]2XeO3 and (C5H5NO)3(XeO3)2 are air-stable at room temperature. The xenon coordination sphere in [(C6H5)3PO]2XeO3 is a distorted square pyramid and provides the first example of a five-coordinate Xe center in a XeO3 adduct. The xenon coordination sphere of the remaining adducts are distorted octahedral comprised of three equivalent Xe---O secondary contacts that are approximately trans to the primary Xe–O bonds of XeO3. Hirshfeld surfaces of XeO3 and (C6H5)3PO in [(C6H5)3PO]2XeO3 show the adduct is well-isolated in its crystal structure and provide a visual representation of the secondary Xe---O bonding in this adduct. Crown ethers have been known for over 50 years, but no example of a complex between a noble-gas compound and a crown ether or another polydentate ligand had been reported. Xenon trioxide is shown to react with 15-crown-5 to form the kinetically stable (CH2CH2O)5XeO3 adduct which, in marked contrast with solid XeO3, does not detonate when mechanically shocked. The crystal structure shows that the five oxygen atoms of the crown ether are coordinated to the xenon atom of XeO3. The gas-phase Wiberg bond valences and indices and empirical bond valences indicate the Xe---Ocrown bonds are predominantly electrostatic, σ-hole, bonds. Mappings of the electrostatic potential (EP) onto the Hirshfeld surfaces of XeO3 and 15-crown-5 in (CH2CH2O)5XeO3 and a detailed examination of the molecular electrostatic potential surface (MEPS) of XeO3 and (CH2CH2O)5 reveal regions of negative EP on the oxygen atoms of (CH2CH2O)5 and regions of high positive EP on the xenon atom that are also consistent with σ-hole bonding. Reactions of crown ethers with HF acidified aqueous solutions of XeO3 at room-temperature yielded adducts of 12-crown-4, (CH2CH2O)4XeO3, and 18-crown-6, [(CH2CH2O)6XeO3∙2H2O]2∙HF, whereas slow cooling of a solution of XeO3 with 18-crown-6 in acetone yielded (CH2CH2O)6XeO3∙2H2O. The adducts (CH2CH2O)4XeO3 and (CH2CH2O)6XeO3∙2H2O are shock-insensitive whereas the former adduct is air-stable at room temperature. The low-temperature, single-crystal X-ray structures show the Xe atom of XeO3 coordinated to the oxygen atoms of the crown ether ring. Uncharacteristic xenon coordination numbers exceeding six (including the three primary bonds of XeO3) were observed for all crown ether adducts. Raman spectroscopy frequency shifts are consistent with complex formation and provided evidence for the 2,2,1-cryptand adduct of XeO3. Gas-phase Wiberg bond valences and indices and empirical solid-state bond valences confirmed the electrostatic nature of the Xe---O bonding interactions. Comparisons between the XeO3 and SbF3 18-crown-6, 15-crown-5, and 12-crown-4 complexes are made. Incorporation of xenon trioxide, XeO3, into inorganic polyatomic salts under ambient conditions has been observed in several mixed xenate salts; K[XeO3XO3] (X = Cl, Br), K2[XeO3SeO4]∙HF, K[(XeO3)nZO3] (Z = I, N), and M2[(XeO3)nCO3]∙xH2O (M = Na, K, Rb, Ba). Raman spectroscopy was used to identify the aforementioned compounds and K[XeO3ClO3], K[XeO3BrO3], K2[XeO3SeO4]∙HF, and Rb2[(XeO3)2CO3]∙2H2O were also characterized by low-temperature, single-crystal X-ray diffraction. The xenon atom of XeO3 is seven coordinate in K[XeO3ClO3] and six coordinate in all other compounds with Xe---O distances that are significantly less than the sum of the Xe and O van der Waals radii. These salts provide examples of XeO3 coordinated to inorganic compounds and may provide insights into the inclusion of xenon oxides in minerals. / Thesis / Master of Science (MSc)
537

The Doctrine of the Atonement in the Writings of C.S. Lewis

Vendetti, Rebecca January 2019 (has links)
This dissertation examines the theology of C.S. Lewis in light of the writings of Athanasius, Augustine, and Anselm. Specifically, it looks at the role that justice and mercy play in each of these theologian’s understanding of the atonement. It proceeds on the basis that Lewis does in fact have a specific, robust, and coherent understanding of the atonement, and that his theological anthropology and his understanding of sanctification are an outworking of his understanding of the atonement. Chapter 1 lays out Lewis’ theological orientation and his method. Chapter 2 engages with Athanasius, Augustine, and Anselm on the atonement, and it lays out the particular concepts that were crucial in their understanding of the atonement, namely the justice and mercy of God. It outlines the fundamental concepts that we find in seedling form in Athanasius and Augustine and that were brought to full fruition in Anselm. It also argues that Anselm’s satisfaction theory is best understood as grounded in the nature of God, rather than in Anselm’s feudal, Medieval context. Chapter 3 examines Lewis on the atonement, and it traces the concepts that Lewis uses to describe and explain Christ’s death and resurrection. While Lewis does not adhere to any one doctrine or understanding of the atonement, there is a common thread that unites the various pictures that he takes to be true representations of the atonement. Fundamentally, for Lewis, the atonement is about the restitution of proper order that was disrupted in the Fall. Chapter 3 examines which theories of the atonement Lewis accepts and which he rejects. It also traces his understanding of the atonement to his understanding of the nature of God, relying on the concept of justitia defined as proper order, which has its source in the nature of God himself. In so doing, it aims to show that Lewis’ later understanding of the atonement is fundamentally Anselmian. Chapter 4 engages with Lewis’ theological anthropology and his understanding of sanctification, focusing on the process of “good infection” and how Lewis envisions the spread of the new life made available after Christ’s act of atonement. Sanctification, for Lewis, like the atonement, is also fundamentally about proper order. This plays out in his theological anthropology largely in terms of humility and obedience to God. Finally, chapter 5 addresses Narnia specifically and traces the concepts of justitia and proper order throughout the series and aims to show that, by focusing on proper order, we can see how the series hangs together as a whole theologically as an outworking of Lewis’ understanding of the atonement. / Thesis / Doctor of Philosophy (PhD)
538

The imagination in education and the contribution of C.S. Lewis /

Longacre, Judith Evans January 1987 (has links)
No description available.
539

Om begreppet sorg : med stadig hänsyn till tröstens problem

Wallnér, Carl January 2024 (has links)
In the following essay, one of grief’s central problems, namely its relation to consolation, is examined. Ancient philosophers’ answers to the question are compared with contemporary ones. Interestingly, although these answers and their theoretical frameworks largely differ, they seem to have one essential point in common, which is the idea that afterlife, understood either as metaphysical or non-metaphysical concept, lies at the core of what makes consolation intelligible. What is put into question in this essay is therefore this rather daring thing: does really the idea of afterlife, when faced with death, console grief, and if not, is there anything left to offer any consolation?
540

An Interactive Chemical Equilibrium Solver for the Personal Computer

Negus, Charles H. 20 February 1997 (has links)
The Virginia Tech Equilibrium Chemistry (VTEC) code is a keyboard interactive, user friendly, chemical equilibrium solver for use on a personal computer. The code is particularly suitable for a teaching / learning environment. For a set of reactants at a defined thermodynamic state given by a user, the program will select all species in the JANAF thermochemical database which could exist in the products. The program will then calculate equilibrium composition, flame temperature, and other thermodynamic properties for many common cases. Examples in this thesis show VTEC's ability to predict chemical equilibrium compositions and flame temperature for selected reactions, and demonstrate how VTEC can substitute for and aid in the design of lab experiments, and identify trends in parametric studies. The 1976 NASA Lewis Chemical Equilibrium Code (CEC76) from which VTEC has been adapted uses Lagrangian multipliers to minimize free energy. CEC76 was written for mainframe computer use. Later versions of CEC76, adapted for personal computer use are available for a fee and have a very minimal user interface. / Master of Science

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