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Vision 2042: Notes Toward a Radical Order TransformedKridler, Jamie Branam 01 May 2010 (has links)
No description available.
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Mn-mediated radical coupling toward synthesis of alpha, alpha-disubstituted alpha-amino esters and formal synthesis of quinineJi, An 01 July 2011 (has links)
Chiral alpha-branched amines are common substructures of bioactive synthetic targets such as alkaloids and amino acids. Direct asymmetric amine synthesis by addition to the C=N bond of carbonyl imino derivatives is promising and efficient to introduce the stereogenic center and carbon-carbon bond in one step. Furthermore, disconnection of either C-C bond at the amine stereogenic center would be the most versatile method to achieve this objective; we could make the choice depending on the different synthetic strategies, such as the availability of precursors and the presence of complicating structural features.
In our group, we disclosed that manganese carbonyl mediates stereoselective photolytic radical addition of alkyl iodides to chiral imino acceptors, which is a powerful tool to form a new C-C bond and generate a chiral center. Qualitative mechanistic studies confirm the importance of free radicals, imply that this is a nonchain (or short chain length) free-radical process, and reveal that organomanganese compounds are not a viable source of alkyl radical for the addition reactions under the conditions in our lab. In my thesis, we have extended the application of our methodology.
At the beginning of my research, our Mn-mediated addition methodology was first applied to accomplish the couplings of iodides and ketone N-acylhydrazones, generating quaternary carbon stereocenters and offering access to a variety of alpha-alkylated alanine analogs. These radical additions complement enolate alkylation methodologies, as they occur under nonbasic conditions and permit introduction of both primary and secondary alkyl groups with relative ease. The versatility with respect to the iodide is a distinguishing feature of the Mn-mediated coupling that foreshadows application to more complex targets.
Secondly, a Mn-mediated radical-ionic annulation strategy was validated as a synthetic route to quinine. Intermolecular radical addition to C=N bonds has rarely been applied as a strategic bond construction in natural product synthesis; this synthesis of quinine offers the strongest demonstration yet of the utility of such reactions in application toward complex multifunctional targets.
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Effects of prepolymer structure on photopolymer network formation and thermomechanical propertiesScholte, Jon Paul 01 May 2017 (has links)
Photopolymerization is a growing field within the realms of polymer and material science. With diverse applications, ranging from coatings and adhesives to newer technologies such as 3D printing photopolymerization continues to increase its prevalence and influence. This research examines fundamental structure property relationships between large prepolymer structures within a formulation and the resulting impact on thermo-mechanical properties in photocurable resins. Most prepolymer molecules utilize a “one pot” synthesis with little to no control over the placement of photoreactive moieties such as epoxies and (meth) acrylates. We have utilized novel prepolymer molecules synthesized using controlled radical polymerization to allow direct control over the placement of reactive groups. The ability to control the location of reactive groups in prepolymer molecules can also lead to the formation of multiple domains within the resulting photocured thermoset. This separation is achieved by concentrating the reactive groups at specific locations in the prepolymer backbone, e.g. at the end or near the center of the prepolymer molecule. The nonreactive groups may form one domain within the thermoset network while the reactive portion of the prepolymer forms a second phase with reactive diluent molecules. Additionally, various architectures allow greater control over polymer network formation and crosslink density. Through these manipulations of macromolecular architecture, we have been able to manipulate various thermo-mechanical properties. Using various architectured prepolymer, we have been able to generate materials with multiple glass transitions while also increasing the rate of reaction and total conversion as compared to randomly functionalized control formulations.
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Experimental and theoretical investigations of active center generation and mobility in cationic and free-radical photopolymerizationsHoppe, Cynthia Caroline 01 May 2010 (has links)
Photopolymerization is considered an attractive alternative in many industries to traditional polymerization processes. The advantages of photopolymerization over other types of polymerization include elimination of heat sources, faster cure times, and reduction in the use of volatile organic solvents. Despite these environmental and cost-saving advantages, photopolymerizations have several limitations. Light attenuation can be a problem for systems containing pigments or fillers. The radiation source penetrates only to a shallow depth beneath the surface, limiting the thickness of strongly pigmented or filled coatings and films. Photopolymerization is also generally limited to systems with simple geometries that can be uniformly illuminated. Coatings on three-dimensional substrates, or other systems with complex geometries, are difficult to uniformly cure. These problems can be solved by "shadow cure," which is defined as the reactive diffusion of photoinitiated active centers into regions of a polymer that are unilluminated. In this contribution, the generation and subsequent spatial and temporal evolution of the active center concentrations during illumination are analyzed using the differential equations that govern the light intensity gradient and photoinitiator concentration gradient for polychromatic illumination. Reactive diffusion of the active centers during the post-illumination period is shown to result in cure of unilluminated regions. A kinetic analysis is performed by coupling the active center concentration profiles with the propagation rate equation, yielding predicted cure times for a variety of applications. This analysis is used for the evaluation of cationic shadow cure in pigmented photopolymerization systems, and systems with complex geometries. The extensive characterization of cationic systems is then applied to free-radical photopolymerization to examine the potential of shadow cure for active centers with much shorter lifetimes. An example of a free-radical photopolymerization system is characterized in which the dimensional scales are small enough to utilize the short lifetimes of the active centers. The results presented for both free-radical and cationic shadow cure indicate that the reactive diffusion of photoinitiated active centers may be used for effective cure in unilluminated regions of a photopolymer. This research will potentially allow photopolymerization to be applied in industries where it has never before been utilized.
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Steady State and Theoretical Investigations of Peptidylglycine α-Amidating Monooxygenase (PAM)Lowe, Edward W 14 November 2008 (has links)
Approximately 50 percent of all known peptide hormones are post-translationally modified at their C-terminus. These peptide hormones are responsible for cellular functions critical to survival. Peptidylglycine alpha-amidating monooxygenase (PAM) is a bi-functional enzyme which catalyzes the conversion of peptide pro-hormones to peptide hormones.
PAM is the only known mammalian enzyme that catalyzes the necessary alpha-amidation to activate these peptide hormones. PAM has previously been found to perform N-dealkylation, as well as O-dealkylation. We report here that a novel chemistry for PAM, S-dealkylation, has now been shown. PAM was able to catalyzes the hydroxylation and subsequent dealkylation for a series of substituted 2- (phenylthio)acetic acid analogs, leaving a product containing a free thiol capable of coordinating to copper(I).
A series of cinnamic acid derivatives have been investigated as turnover dependent inactivators of PAM. It was shown that the inactivating compounds contained electron donating substituents. All compounds bound competitively versus substrate, though no catalytic activity was noted when tested as substrates. Although no Dkinact was observed when using perdeuterated cinnamic acid, one cannot rule out hydrogen abstraction from the Cα as this step may not be rate limiting for inactivation. This suggests that the activated oxygen species generated at CuM may be sufficiently reactive to abstract a hydrogen from an alkene to generate a vinyl radical. Substrate activation is believed to be facilitated by a Cu(II)-superoxo complex formed at CuM. Hydrogen abstraction from the Cα is hypothesized to generate a radical, though this has never been demonstrated spectrometrically. We report here further evidence for the generation of an Ca radical by comparing log(Vmax/KO2) vs σ+ for a series of ring-substituted 4-phenyl-3- butenoic acids.
Lastly, a computational study was carried out to probe for a possible binding pocket for the reductant, ascorbate. Though crystal structures have argued that reduction of the enzymebound coppers is collisional, kinetic data for inhibitors competitive against ascorbate indicates that a discrete binding pocket may exist. Our study suggests a specific site for binding and provides free energy calculations in agreement with experimental values for binding constants.
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The Voices of Sex Workers (prostitutes?) and the Dilemma of Feminist DiscourseKessler, Justine L 28 April 2005 (has links)
The existence of prostitution has been a longtime concern for many societies. It has also been a complicated issue within feminist discourse. Some women choose sex work as a viable economic option while others are forced into prostitution by traffickers and pimps and some are forced into it due to disadvantaged circumstances. The presence of sex work and prostitution is one of the occurrences that accompany a patriarchal capitalist system. Many feminists indeed argue that prostitution is a byproduct of a patriarchal capitalist system. The migration of women for sex work and the trafficking of women into prostitution cannot occur without participation of a dominant more powerful group, and a marginalized less powerful group. Sex work and prostitution are complicated components in an ever increasingly connected world. However, all too often, the belief that a patriarchal capitalist system supports the migration of women for sex work and the trafficking of women into prostitution fails to encompass all the complexities surrounding these occurrences.
The existence of sex work and prostitution involves legal, economic, political, and moral implications that deserve broad theorization. In order to more fully understand the legal, economic, political, and moral implications that contribute to the existence of sex work and prostitution, the voices of women that are involved must be illuminated. While this interview does not yet exist, I argue that only through interviews of women in sex work and prostitution can we fully understand the issue. Illuminating the voices of these women will help to reveal how issues surrounding sex workersí agency and victimization of trafficked women are present and absent within feminist discourse.
This thesis focuses on the differences between women sex workers with agency and women who are victims of trafficking and pimping. It also discusses the migration of women into the sex industry. The discussion of agency and victimization is applied to modern and postmodern feminist theory. Modern feminist theory is useful to an understanding of how sex work and prostitution are oppressive to the women involved and how conditions of agency and victimization are supported and/or negated. Postmodern feminist theory transforms the focus of the discussion from the identity of sex workers and prostitutes as agents and victims to a discussion of these women as subjects. First person interviews by sex workers reveal their subjectivity and supports the argument that what they do is indeed work, and it is viewed as such by the women themselves. Inclusion of the voices of sex workers and prostitutes also reveals the issues and concerns that they experience as employees in sex work and prostitution.
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Magnetic Exchange Coupling in 3d and 4f Complexes Using Radical Tetrazine-based FrameworksAlves Lemes, Maykon 11 September 2019 (has links)
High symmetry and low coordinated single-ion lanthanides have been a successful recipe to design high performance single molecule magnets (SMMs). However, enhancement of the magnetic properties of polymetallic SMMs is an important challenge. Therefore, this thesis describes the use of redox non-innocent tetrazine-based ligands and d- and f- elements in order to fine-tune the electronic structure of the resulting compounds to promote strong exchange interactions between the spin carriers. As reported in the literature, radical-bridged ligands represent a potential strategy to improve the magnetic properties of polymetallic SMMs. Thus, chapter one introduces principal concepts that govern the physical properties of metal complexes containing radical-bridged ligands.
Chapter two describes the magnetic properties of a unique air-stable tetratopic radical- bridged bpymtz•− (3,6-bis(2-pyrimidyl)-1,2,4,5-tetrazine) templating four Ni(II) metal ions. The dc magnetic studies along with DFT calculations reveal strong ferromagnetic exchange coupling between the Ni− bpymtz•− of J = 98 cm-1 with a spin ground state of S = 9/2.
Chapter three describes the application of another tetrazine-based ligand, bpytz (3,6- bis(3,5-dimethylpyrazolyl)-1,2,4,5-tetrazine) to probe magnetic exchange interactions in a {CoII4} supramolecular square. The modelling of dc susceptibility data shows significant Co(II) - bpytz•− magnetic coupling of J = - 118 cm-1 for a spin ground state ST = 4. While the non-reduced analog displays weak Co(II)-Co(II) exchange of J = - 0.64 cm-1 (S = 0 ground state). Additionally, the radical-radical magnetic exchange contribution was probed with an analogous {ZnII4} square, where a J = -15.9 cm-1 was found.
Chapter four extends the application of reduced tetrazine ligands to lanthanide systems. Here we demonstrate that the systematic reduction of the ligand with cobaltacene (CoCp2) led to the formation of a strongly coupled bpytz•−−bpytz•− bridging ligand. Magnetic measurements combined with ab initio calculations confirm unprecedented intramolecular pi-dimerization preventing strong magnetic Dy(III)−bpytz•− communication.
Chapter five describes the synthesis and characterization of {LnIII4} (Ln = Dy, Gd and Lu) where the Ln(III) ions are bridged by peripheral bpytz•−. The oxophilicity and high coordination numbers preferred by lanthanides ions lead to the formation of a cubane core made up of metal ions bridged by hydroxy ligands (M3-OH−). Experimental and computational studies were applied to verify the nature and strength of the magnetic interactions between the spin carriers.
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"Patterns in a world in slippage": playback theatre as professional development in three primary healthcare centres in Aotearoa New ZealandDay, Fe January 2007 (has links)
This thesis is an account of praxis: it examines Playback conceptually, and portrays a programme of practical work exploring the experience of workplace audiences of five Playback Theatre performances, delivered from 2002-2005. The aim of the performances was to assist multi-disciplinary teams of staff in community health centres in Auckland New Zealand to communicate and work together with more understanding of each other. The thesis describes Playback as a way not only to elicit complex narratives which allow for diverse points of view to be expressed, but also as an aesthetic reworking of these narratives using action, music, dance, gesture and speech, in ways which have been influenced by 20th century avant-garde forms such as surrealism, dada, collage, jazz and poetry. Unlike some forms of theatre, Playback calls on elements of ritual and group method, in that it relies on audience members taking an active part in the performance by contributing narratives from their own lives. The thesis interrogates the notion of audience in theatre, using the words audience, spectator, spectactor, participant, public and polis, and specifically investigates two moments of the theatre as polis, in the French and Russian revolutions, when the potential of theatre to engage with the widest cross-section of the nation led to influential experiments and innovations in theatrical practice, each of which influenced the succeeding century. Some Playback discourse and practice is found to contain simplistic, even nostalgic, concepts of personal narrative, and the potential for performers’ interpretations in Playback to reinscribe social privilege is noted. In spite of its simple structure, Playback demands extremely complex skills from all the performers, not only the facilitator. In addition, the complex setting of the practical work encompasses both local NZ health initiatives and developments in global health. The work in each Healthcare Centre is described in a complete chapter: each containing details of the Centre and the Playback, seen through the findings of the patient focus groups, through comments made in interviews by the staff and through the researcher’s observation and experience. In all three Centres, existential and emancipatory metanarratives surfaced in the performances and in interviews. Professionalism was seen as meaning different things: at Ngākau it was a measure by which people were found to be unsatisfactory; at Oranga, it referred to applying the lessons of the Playback to one’s own practice; while at Pātaka, professionalism was evident in narratives of self care, dedication and seeking clarification and support from peers. While the study revealed limitations of Playback, it also pointed to some unique contributions this form of improvisational theatre can make to a programme of staff or group development. In particular, Playback can open up spaces, people and topics, for non-dogmatic, pluralistic, embodied thinking and reflection, leading people to more nuanced understandings of themselves and each other, and can even affect attitudes and behaviours.
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Creativity and embodied learningWright, David, University of Western Sydney, Faculty of Social Inquiry, School of Social Ecology January 1998 (has links)
This thesis looks at the way in which drama education constructs opportunities for learning. Constructivism and self-organising systems theory are used to further understand how individuals and societies construct their own learning. Important in this process is the self-conscious experience of the learner. The notion of being ‘in learning’ rather than outside of and observing the learning is central. This consciousness facilitates the creation of meaning, which plays a role in determining the manner in which further participation in learning occurs, hence further learning. This emphasises the process of learning over the product of learning. The function that language and emotion serve in this process also deserves consideration. This perspective upon process has a considerable impact upon the way in which learners make meaning and the way in which they approach learning. Questions surrounding a consciousness of participation bring the senses, the feelings, the emotions and other physical experience to the fore. They require that the learning of the body be experienced. Embodied learning is insufficiently acknowledged and theorised in drama education. Through bringing together constructivism, systems theory, drama education and contemporary performance theory this thesis argues for a greater recognition of the relationship between the body and learning. / Doctor of Philosophy (PhD)
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Surface grafting of polymers via living radical polymerization techniques; polymeric supports for combinatorial chemistryZwaneveld, Nikolas Anton Amadeus, Chemical Engineering & Industrial Chemistry, UNSW January 2006 (has links)
The use of living radical polymerization methods has shown significant potential to control grafting of polymers from inert polymeric substrates. The objective of this thesis is to create advanced substrates for use in combinatorial chemistry applications through the use of g-radiation as a radical source, and the use of RAFT, ATRP and RATRP living radical techniques to control grafting polymerization. The substrates grafted were polypropylene SynPhase lanterns from Mimotopes and are intended to be used as supports for combinatorial chemistry. ATRP was used to graft polymers to SynPhase lanterns using a technique where the lantern was functionalized by exposing the lanterns to gamma-radiation from a 60Co radiation source in the presence of carbon tetra-bromide, producing short chain polystyrene tethered bromine atoms, and also with CBr4 directly functionalizing the surface. Styrene was then grafted off these lanterns using ATRP. MMA was graft to the surface of SynPhase lanterns, using g-radiation initiated RATRP at room temperature. It was found that the addition of the thermal initiator, AIBN, successfully increased the concentration of radicals to a level where we could achieve proper control of the polymerization. RAFT was used to successfully control the grafting of styrene, acrylic acid and N,N???-dimethylacrylamide to polypropylene SynPhase Lanterns via a -initiated RAFT agent mediated free radical polymerization process using cumyl phenyldithioacetate and cumyl dithiobenzoate RAFT agents. Amphiphilic brush copolymers were produced with a novel combined RAFT and ATRP system. Polystyrene-co-poly(vinylbenzyl chloride) created using gamma-radiation and controlled with the RAFT agent PEPDA was used as a backbone. The VBC moieties were then used as initiator sites for the ATRP grafting of t-BA to give a P(t-BA) brush that was then hydrolyzed to produce a PAA brush polymer. FMOC loading tests were conducted on all these lanterns to assess their effectiveness as combinatorial chemistry supports. It was found that the loading could be controlled by adjusting the graft ratio of the lanterns and had a comparable loading to those commercially produced by Mimotopes.
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