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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.
451

Radicals Online: Ted Kaczynski and the Anti-Tech Collective

Brown, Mitchell J 01 August 2022 (has links)
After Ted Kaczynski’s manifesto, Industrial Society and its Future, was published it hasbegun a small, but growing movement of people who support his ideas. After beginning my research, I have seen a rise in the visibility of Kaczynski’s ideas online. This thesis focuses on the Anti-Tech Collective (ATC) who, as a radical online community has begun promoting his ideas. This thesis has used communication phenomenology as a method to see how the ATC views their relationship with Kaczynski and his writings. In further analysis I then used Freudian defense mechanisms, repurposed as account structure as a way for the ATC to maintain social acceptability while promoting a radical ideology. In this research, I identified ways that the ATC views Kaczynski and his ideas and where this fits in online radicalism. These methods can be employed in looking at any radical online community where its members desire to maintain some level of social acceptability.
452

Enantioselective Synthesis and Stereospecific Transformation of Alkylboronates:

Xu, Peilin January 2022 (has links)
Thesis advisor: James P. Morken / Thesis advisor: Marc L. Snapper / This dissertation will present three projects focusing on the enantioselective synthesis and stereospecific transformation of alkylboronates. The first project describes the development of a nickel-catalyzed enantioselective dicarbofunctionalization of alkenylboronates, which provides a modular route to secondary alkylboronic esters. Intramolecular reaction leads to enantioselective synthesis of exocyclic boronates. The second project depicts a new method for the synthesis of azetidines, pyrrolidines and piperidines via an intramolecular amination of alkylboronic esters. Regioselective amination of vicinal bis(boronates) allows the synthesis of saturated azacycles bearing boronic ester substitutions that can serve as useful synthetic handles. As the transformation is stereospecific, stereodefined cyclic amines can be synthesized from the enantioenriched boronic esters. The method is applied to the synthesis of an intermediate towards a Kras G12C inhibitor. The third project describes the development of a new chiral auxiliary on boron that can be easily synthesized from inexpensive starting materials. The auxiliary is applied to a diastereoselective radical ring-opening/closing [3+2] cycloaddition of cyclopropylanilines with alkenylboron species. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.
453

Initiation and Termination of a Hybrid Atom Transfer Radical Polymerization System / Initiation and Termination of a Hybrid ATRP System

Machado, Mark 06 1900 (has links)
Atom transfer radical polymerization (ATRP) is a controlled/living polymerization process used to synthesize polymers with controlled molecular weight and narrow polymer distributions. Control of these key parameters allows for the fabrication of well-defined macromolecular structures, a necessary tool for the synthesis of advanced materials. Since its discovery in 1995, ATRP has received considerable interest and widespread adoption from the academic community. Unfortunately, it faces several complex challenges which have hindered its full scale commercialization, mainly its high catalyst loadings to obtain fast reaction kinetics. One of the premises of this research project was to augment the slow reaction rates of ATRP while using extremely low catalyst concentrations. A hybrid ATRP system was employed which encompassed the fast reaction kinetics associated with conventional free radical processes, with the attractive control features of ATRP. When high free radical initiator concentrations in the range of 0.1 M to 0.2 M were used in concert with ATRP, fast reaction rates were realized, while maintaining a polymerization with living characteristics. Conversions of 81% (0.117M) and 91% (0.234M) were achieved within 2 hours as compared to typical ATRPs where achieving such conversions would take up to 24 hours. For those same free radical initiator loadings (0.117M and 0.234M) the reaction demonstrated living characteristics with molecular weight growing in a linear fashion with respect to increasing monomer conversion. Despite the high free radical initiator concentration, the polymer distribution remained relatively narrow, not exceeding a polydispersity of 1.30. Chain extension experiments from a synthesized macroinitiator were successful which demonstrated the living characteristics of the hybrid ATRP process. The aforementioned polymerizations were conducted with various copper concentrations. Catalyst concentrations as low as 16 ppm (0.234mM) were found to be effective, i.e. one catalyst mediated the growth of over 100 polymer chains, and thus saving post polymerization purification. Moreover, the expensive ligand cost could be cut dramatically through a nearly 100 time reduction in the ligand concentration for these polymerizations. A hybrid ATRP system was used as a unique method to determine termination rate coefficients of MMA at 70°C as a function of both conversion and chain length. A three dimensional composite map was developed to elucidate the coupling effects of both conversion and chain length on the termination rate coefficient over a total range of data which can be used for modelling systems of this nature. / Thesis / Master of Applied Science (MASc)
454

Civil Disobedience as a Radical Flank in the Mountain Valley Pipeline Resistance Movement

Baller, Cameron Reid 19 May 2023 (has links)
Communities of resistance are increasingly turning to radical tactics, including acts of civil disobedience, to fight back against encroaching fossil fuel infrastructure. The fight against the Mountain Valley Pipeline (MVP) is no exception. The MVP is a 303-mile long proposed fracked gas pipeline in Virginia and West Virginia. I apply radical flank effect (RFE) theory and the theory of movement dynamism to understand the role of civil disobedience, as a radical flank, in the MVP resistance movement. I contribute to the literature on RFEs by focusing primarily on how the radical flank of this movement has affected within-movement social dynamics, like trust, unity, and interpersonal relations. I rely on 15 semi-structured interviews with pipeline fighters, both those who have and have not participated in acts of civil disobedience, to gain insight into the use of civil disobedience, as a radical flank in the movement. This movement has used diverse tactics to challenge construction of the MVP, making it a strong case for understanding the role of radical tactics, and their relationship to moderate tactics. I find several positive RFEs (energizing effects, connecting effects, engaging effects, uniting effects, and movement outcome effects) and some potential negative RFEs (conflict/alienation, fear of consequences and organizational risks). I also find evidence of movement dynamism in the form of an ecosystem of tactics which emerged in the MVP resistance movement. Movement actors kept moderate and radical flanks publicly separate for strategic reasons while overlapping membership bridged the social dynamics of the movement, encouraging cohesion and collective movement identity. / Master of Science / Communities concerned about climate change are increasingly breaking the law in order to make their voices heard and stop dangerous coal, oil and natural gas projects. These actions are called civil disobedience and they have been used for decades in the United States, most prominently in the Civil Rights Movement. One such example in the fight against climate change is the resistance to the Mountain Valley Pipeline, a 303-mile long proposed natural gas pipeline in Virginia and West Virginia. I use social movement theories to understand the role that civil disobedience has played in the Mountain Valley Pipeline resistance movement. Specifically, I look at how the use of civil disobedience in this movement has affected the social dynamics of the movement, like trust, unity, or relationships in the movement. I spoke with 15 community members who have been active in fighting this pipeline to learn more. This movement has involved a wide range of different tactics, including civil disobedience, so it is a strong example to study for this research. My interviews with the community members revealed several positive effects as a result of the use of civil disobedience in the movement as well as a few potential risks/dangers. I also found that civil disobedience was able to work together with other types of tactics in a vibrant ecosystem that included mutual benefit. At the same time, I find that community members sought to keep some of the illegal tactics separate from more moderate tactics, like lawsuits or public comment submissions, in order to keep the moderate tactics safe. Despite this separation, I find that significant overlap of community members across different types of tactics was able to maintain a cohesive, common identity and unify people who were participating in different tactics, but fighting the same pipeline.
455

Using Eye-Tracking to Examine How Chinese Foreign Language Learners Attend to Chinese Radicals

Lin, Yi Hsuan 07 March 2024 (has links) (PDF)
This study utilized eye-tracking to investigate 63 intermediate-level university Chinese foreign language (CFL) learners' real-time radical preferences. Radicals are components of Chinese characters and give clues to the meanings and pronunciations of the character. This study aimed to answer the following research questions: (1) What type of radicals (semantic/phonetic) do CFL readers most rely on when reading characters? (2) Does reliance on one type of radical (semantic/phonetic) correlate with accuracy in character recognition? (3) Does awareness of semantic/phonetic radicals affect the accuracy of character recognition or reliance on radicals in real-time processing? The results found that participants demonstrated a phonetic bias in that they had more proportion of looks on phonetic over semantic radicals in real-time reading. Furthermore, participants' radical awareness and radical identification scores positively correlated with accurate character recognition. Pedagogical applications drawn from this study suggest that future instructors should explicitly teach radical identification to CFL learners to facilitate character decoding.
456

Well-motivated reformists or nascent radicals: How do applicants to the degree in social work see social problems, their origins and solutions?

Gilligan, Philip A. 06 1900 (has links)
No / This article reports ways in which applicants to the Degree in Social Work see `social problems¿, their origins and possible solutions to them. What is demonstrated is that whilst applicants are concerned about a range of problems, those which could be broadly classified as `anti-social behaviours by individuals or groups¿ predominate, in contrast to those which could be defined as `aspects of the social structure which have an adverse impact on individuals or groups¿. Applicants are much more likely to suggest `individual¿ rather than `social¿ causes and are most likely to suggest `liberal/reformist¿ solutions. It is argued, in the context of frame analysis, that pre-existing views will usually impact strongly on how students respond to the knowledge and challenges offered during training. The article aims to place discussion within consideration of wider issues, particularly whether social work in Britain can maintain its historic commitment to social justice and prevent itself becoming an increasingly uncritical tool of the UK government¿s social authoritarianism. Finally, it seeks to raise questions about whether social work education can assist qualifying workers to develop and maintain resiliently radical approaches to practice, which are also effective in bringing positive change to vulnerable and disadvantaged people.
457

Development and Application of Coupled Cluster Ground- and Excited-State Models

Smith, Christopher Edward 08 May 2006 (has links)
We give an overview of quantum chemical methods with a particular emphasis on the development of high-accuracy quantum chemical models. The reliability of these methods often hinges on whether enough electron correlation is included in the truncated wave function. As an example, we investigate the structures of m-benzyne and its fluorinated derivative, tetrafluoro-m-benzyne where the inclusion of triple excitations is paramount to correctly describe through-bond delocalization of the monocyclic form. At the CCSDT/6-31G** level of theory, the C1–C3 distance of the minimum energy form of m-benzyne is 2.0°A and the profile of the PES along the C1–C3 distance is that of an asymmetric, single-well, in agreement with previous density-functional theory and coupled cluster studies. In addition, the calculated CCSD(T) fundamental frequencies are in excellent agreement with the measured infrared frequencies, thus confirming the monocyclic form of m-benzyne. For tetrafluoro-m-benzyne, however, the increased eclipsing strain between the ring-external Câ X bonds stabilizes the bicyclo[3.1.0]hexatriene form: the C1–C3 distance is calculated at the CCSD(T)/cc-pVTZ level to be approximately 1.75 °A, which is in the range of elongated CC bonds. Computed harmonic vibrational frequencies compare reasonably well with the experimental neon-matrix difference spectrum and provide further evidence for the existence of a bicyclic form. We also report an extension of the coupled cluster iterative-triples model, CC3, to excited states of open-shell molecules, including radicals. We define the method for both spin-unrestricted Hartree-Fock (UHF) and spin-restricted open-shell Hartree-Fock (ROHF) reference determinants and discuss its efficient implementation in the PSI3 program package. The program is streamlined to use at most O(N7) computational steps and avoids storage of the triple-excitation amplitudes for both the ground-and excited-state calculations. The excitation-energy program makes use of a Lowdin projection formalism (comparable to that of earlier implementations) that allows computational reduction of the Davidson algorithm to only the single- and double-excitation space, but limits the calculation to only one excited state at a time. However, a root-following algorithm may be used to compute energies for multiple states of the same symmetry. Benchmark applications of the new methods to the lowest valence 2B1 state of the allyl radical, low-lying states of the CH and CO+ diatomics, and the nitromethyl radical show substantial improvement over ROHF- and UHF-based CCSD excitation energies for states with strong double-excitation character or cases suffering from significant spin contamination. For the allyl radical, CC3 adiabatic excitation energies differ from experiment by less than 0.02 eV, while for the 2§+ state of CH, significant errors of more than 0.4 eV remain. Finally, ground- and excited-state dipole moments are derived diagramatically and were recently developed within the PSI3 quantum chemistry package. However, convergence problems with computing the left-hand excited-state has prevented us from reporting any meaningful results. Thus, future work includes solving this convergence problem before the effects of triple excitations on one-electron properties can be reported with certainty. / Ph. D.
458

Living Polymerization for the Introduction of Tailored Hydrogen Bonding

Elkins, Casey Lynn 15 August 2005 (has links)
In an effort to synthesize macromolecules comprising both covalent and non-covalent bonding to tune ultimate physical properties, a variety of methodologies and functionalization strategies were employed. First, protected functional initiation, namely 3-[(N-benzyl-N-methyl)amino]-1-propyllithium and 3-(t-butyldimethylsilyloxy)-1-propyllithium, in living anionic polymerization of isoprene was used to yield well-defined chain end functional macromolecules. Using both initiating systems, polymers with good molar mass control and narrow molar mass distributions were obtained and well-defined chain end functionality was observed. There was no observed effect on the polymer microstructure from the polar functionality in the initiator, with ~92% 1,4- and 8% 3,4-enchainment observed in each case. Further investigation of the 3-[(N-benzyl-N-methyl)amino]-1-propyllithium initiated polyisoprenes proved that facile deprotection was not possible and residual catalyst was not removable from the polymer. However, polymers initiated with 3-(t-butyldimethylsilyloxy)-1-propyllithium were quantitatively hydrogenated and deprotected under relatively mild conditions to yield hydroxyl functional macromolecules in several architectures, including linear and star-shaped. Excellent conversion from arm polymer to star polymer was observed and well-defined macromolecules were obtained. Subsequently, a series of non-functional, hydroxyl functional, and 2-ureido-4[1H]-pyrimidone (UPy) chain end functional linear and star-shaped poly(ethylene-co-propylene)s were synthesized and characterized. The melt phase properties were investigated using melt rheology and the effect of macromolecular topology and multiple hydrogen bond functionality was investigated. Linear UPy functional poly(ethylene-co-propylene)s exhibited increased viscosity and shear thinning onset at lower frequencies than non-functional polymers of similar molar mass due to interaction of the multiple hydrogen bonding groups. Star-shaped UPy functional poly(ethylene-co-propylene)s showed inhibition to terminal flow and the absence of a zero shear viscosity in melt rheological characterization, indicative of a network like structure imparted from the multiple hydrogen bonding interactions. In addition, the living anionic polymerization of D3 was controlled using the functionalized initiators3-[(N-benzyl-N-methyl)amino]-1-propyllithium and 3-(t-butyldimethylsilyloxy)-1-propyllithium. Good molar mass control and narrow molar mass distributions were observed. In contrast to the polyisoprene homopolymers, facile deprotection of the 3-(t-butyldimethylsilyloxy)-1-propyllithium was not possible due to the acid sensitivity of the poly(dimethylsiloxane) backbone. However, facile deprotection of the protected secondary amine was achieved through hydrogenolysis and well-defined terminal amine functionalized poly(dimethylsiloxane) was synthesized, which are then amenable to further functionalization reactions. In contrast to the well-defined polymers synthesized using living anionic polymerization, free radical polymerizations was used to synthesize free radical copolymers with broader polydispersities and pendant UPy groups. These copolymers were compared with a simple dimeric hydrogen bonding carboxylic acid containing copolymer. Melt rheological characterization revealed that, at similar concentrations, the effect of the UPy group was much greater than the carboxylic acid, and broadened plateau moduli and increased viscosity for the UPy containing polymers were observed, while the acid containing polymer exhibited similar results to a non-functional control. The dynamic viscosity was observed to increase systematically with increasing UPyMA incorporation and the quadruple hydrogen bonding interactions were observed to dissociate between ~80-150 °C. / Ph. D.
459

New Methods for the Formation of Methyl Bearing Stereogenic Centers via Methylketene Dimerization and Free Radical Additions to Allyl Bromides

Struss, John Anthony 12 September 2002 (has links)
Two organic synthetic methods for the generation of methyl bearing chiral centers have been developed using: 1) dimerization of methylketene and 2) a free radical-based addition/elimination reaction involving allyl bromides. The first method, the asymmetric dimerization of methyl ketene, followed by an asymmetric aldol reaction and the appropriate functional group manipulations enabled us to construct the (2S, 4S, 6S) trimethylnonyl subunit found in the siphonariene class of natural products. The latter method explored the stereoselective potential of a free radical-based condensation reaction by examining compounds which are known to be able to support chiral auxiliaries and chiral Lewis acids. Additionally, substituent effect on the rates of this reaction were examined closely and found to be comparable to similar, previously examined systems. The synthetic utility, magnitude and scope of this reaction are discussed. / Ph. D.
460

Sterically Crowded Copolymers Based on Functionalized Stilbenes

Li, Yi 02 May 2012 (has links)
The research in this dissertation is focused on the synthesis and characterization of sterically crowded, precisely charged polyelectrolytes based on substituted stilbene comonomers. New sterically crowded polyelectrolytes based on functionalized stilbenes with maleic anhydride or functionalized N-phenylmaleimides were prepared via a "protected" precursor polymer strategy. The polyelectrolyte precursors readily dissolved in organic solvents and were characterized by 1H NMR, SEC, TGA, and DSC. The polyelectrolytes were obtained via simple deprotection chemistries. The use of different combinations of the donor-acceptor comonomer pairs and the alternating copolymerization of these comonomers lead to precise control over charge density and placement of charged groups along the polymer backbone. Analogous styrenic copolymers, for direct comparison to the stilbene structures, were also prepared. Broad peaks in 1H NMR spectra were observed. There were no thermal transitions measured by DSC below the degradation temperature. A strong polyelectrolyte effect, for both stilbene and styrene copolymers, occurred in deionized water and was suppressed by adding NaCl to the polymer solution. These results are not consistent with "rigid" rod polyelectrolytes in which chain collapse in the presence of added salt and chain expansion on dilution should not be observed. In response to these observations persistence length measurements were conducted on the stilbene and styrene copolymers to assess directly the steric crowding effect of added phenyl groups in stilbene copolymers. Both SEC and SAXS measurements were used to obtain persistence lengths. The results from three different approaches, Bohdanecký, graphical and Sharp and Bloomfield Global, were in good agreement. The persistence lengths of stilbene containing copolymers range from 3 to 6 nm and the added phenyl groups increase the rigidity of the polymer chain by about 30-50%. This puts these polymers into a broadly defined "semi-rigid" category of polymers and is consistent with the solution polyelectrolyte effect observed. In dilute solution characterization of stilbene containing polyanions, a 2-step dissociation behavior was observed for the two adjacent carboxylic acids in maleic acid containing polyanions. Stilbene polyanion solutions showed high Rh values in deionized water as shown by DLS measurements and a decrease of Rh values followed by aggregation upon gradual addition of salt. Bimodal peaks were observed in SEC measurements with the copolymer of 4-methylstilbene and maleic anhydride. DLS measurements indicated interchain aggregation as the origin of the apparent high molecular weight fraction. The antiviral activity of the polyanion based on sodium 4-styrenesulfonate and N-(4-sodium sulfophenyl)maleimide was found to be ~50 times higher than the microbicide, sodium poly(styrene sulfonate). The early study of antiviral activities of carboxylated stilbene and styrene polyanions also showed promising results. The synthesis of methyl sulfonate ester-functionalized polyanion precursors was attempted because they can be characterized without the complications caused by directly using charged sulfonate groups. / Ph. D.

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