2,998 research outputs found

    Secondary Coordination Sphere Contributions to Primary Sphere Structure, Bonding and Reactivity.

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    Metalloenzymes are unique in their ability to mediate the transformations of relatively inert substrates with impressive selectivity and speed. Secondary interactions such as hydrogen bonding are broadly appreciated to promote enhanced reactivity in metalloenzymes and are proposed to operate through one of several modes of action; including binding and orienting substrates and stabilizing transition states. In this thesis, transition metal constructs were designed and synthesized to study how secondary coordination sphere perturbations can broadly affect primary sphere structure, bonding and reactivity changes in synthetic systems. Metal complexes supported by a tripodal ligand (tris[quinolyl-2-methyl-7-(morpholinomethanone)]amine, TQA') featuring hydrogen bond acceptor amide groups far removed from the metal center provided a unique example of hydrogen bonding with CH groups. Moreover, these hydrogen bonding interactions to the non-traditional acceptor were shown to influence the primary coordination sphere geometry. In separate studies, a proton-responsive tripodal ligand containing pendent hydroxyl groups (tris(6-hydroxypyrid-2-ylmethyl)amine, H3thpa) was shown to alter coordination geometry and stability of copper halide complexes. Electronic perturbation at the metal center was shown to affect the hydrogen bonding manifold in the secondary coordination sphere of copper chloride complexes through combined crystallographic and computational studies. Copper fluoride complexes supported by H3thpa were investigated and the network of hydrogen bonding interactions presented by the ligand scaffold enabled the isolation of a rare copper(I) fluoride adduct featuring a tripodal ligand. The ability of metal-H3thpa constructs to deliver proton/electron equivalents to a reducible substrate was also demonstrated by exposing a nitrite reduction pathway that is reminiscent of the metalloenzyme copper nitrite reductase. In a final set of studies, transition metal complexes supported by a pincer ligand framework containing tautomerizable hydroxyl groups (6,6'-dihydroxy terpyridine, dhtp) were investigated for catalytic heterolysis reactivity. Ruthenium complexes were studied in detail for catalytic ketone transfer hydrogenation. The role of the pendent hydroxyl groups during catalysis was elucidated and a catalytic cycle is proposed in which alkali metal cations engage substrate to achieve reduction. Together, the studies presented in this thesis demonstrate how secondary coordination sphere interactions can be used to stabilize otherwise reactive products and/or transition states, in analogy to metalloenzymes.PHDChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/113626/1/moorecam_1.pd

    Congratulations, It’s a Boy! Bench-Marking Children’s Perceptions of the Robokind Zeno-R25

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    This paper explores three fundamental attributes of the Robokind Zeno-R25 (its status as person or machine, its ‘gender’, and intensity of its simulated facial expressions) and their impact on children’s perceptions of the robot, using a one-sample study design. Results from a sample of 37 children indicate that the robot is perceived as being a mix of person and machine, but also strongly as a male figure. Children could label emotions of the robot’s simulated facial-expressions but perceived intensities of these expressions varied. The findings demonstrate the importance of establishing fundamentals in user views towards social robots in supporting advanced arguments of social human-robot interaction

    Designing robot personalities for human-robot symbiotic interaction in an educational context

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    The Expressive Agents for Symbiotic Education and Learning project explores human-robot symbiotic interaction with the aim to understand the development of symbiosis over long-term tutoring interactions. The final EASEL system will be built upon the neurobiologically grounded architecture - Distributed Adaptive Control. In this paper, we present the design of an interaction scenario to support development of the DAC, in the context of a synthetic tutoring assistant. Our humanoid robot, capable of life-like simulated facial expressions, will interact with children in a public setting to teach them about exercise and energy. We discuss the range of measurements used to explore children’s responses during, and experiences of, interaction with a social, expressive robot

    Comparative Analysis of Pollution in Farmington Bay and the Great Salt Lake, Utah

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    Farmington Bay covers 94 mi2 (260 km2) in the SW comer of the Great Salt Lake, and is essentially a separate lake because it is enclosed by Antelope Island and a causeway leading to the island from the mainland. The bay has received wastes from the adjoining Salt Lake City metropolitan area for decades. Because of water quality concerns for Farmington 8ay, the Aquatic Ecology Laboratory class at Utah State University studied the bay and a nearby control site (Bridger Bay) in the Great Salt Lake during the fall of 2001. Field sampling and laboratory experiments, as well as other data sources, demonstrated the bay is severely eutrophic and is one of the most polluted water bodies in the state of Utah. A preliminary nutrient loading estimate for the bay indicates that total phosphorus coming into the system is a-times higher than necessary for the bay to be classed as eutrophic. Sewage treatment plants discharging directly to the bay contribute approximately 500/0 of the nutrients. Metrics of eutrophication (chlorophyll, Secchi depth and total phosphorus) all indicated that the bay was hypereutrophic and the combined Trophic State Index was 91, higher than any other lake or reservoir in the state. Oxygen was supersaturated in the surface waters of Farmington Bay during the day, but the bottom water was anoxic. During the night, nearly the entire water column became anoxic due to respiratory demand of the biota. The anoxic conditions allowed high concentrations \u27Of foul-smelling hydrogen sulfide to be produced. Brine shrimp were not abundant in Farmington Bay and the community was dominated by rotifers. In contrast, water quality in Bridger 8ay located on the main lake, was good and brine shrimp were abundant there. Our results, although restricted in scope, corroborate existing monitoring data from this bay. Water quality characteristics in Farmington Bay do not meet those mandated for the protection of aquatic life. Odor problems from the bay likely impact more people than are affected by any other polluted water body in the state. The impact of eutrophication and anoxia on the biota in Farmington Bay may also be substantial, although inadequate data exists to determine these impacts. There are substantial technical challenges to be overcome if water quality in the bay is to be improved to meet its designated use. However, before these technical issues can be solved, the responsible agencies will need to address the problem, and begin studies that may eventually lead to a solution to this serious water quality issue

    Career orientations and career cultures : individual and organisational approaches to beginning teachers’ careers

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    Despite the very large literature on teacher careers from an individual perspective, there is relatively little that links the perspectives of teachers themselves to how schools as organisations approach careers. The aim of this paper is, first, to outline how teachers’ orientations towards careers change across three dimensions, and, second, to examine how schools as organisations deal with career, developing a model of organisational responses, including developing a concept of ‘career culture’, derived from an analysis of interviews regarding the first three years of teaching conducted with senior leaders and second year teachers themselves. By considering the fit between individuals’ career orientations and school career cultures, the paper surfaces both the fluid nature of these orientations and the subsequent potential instability of the fit

    Historical geography II: traces remain

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    The second report in this series turns to focus on the trace in relation to life-writing and biography in historical geography and beyond. Through attention to tracing journeys, located moments and listening to the presence of ghosts (Ogborn, 2005), this report seeks to highlight the range of different ways in which historical geographers have explored lives, deaths, and their transient traces through varied biographical terrains. Continuing to draw attention in historical geography to the darkest of histories, this piece will pivot on moments of discovering the dead to showcase the nuanced ways in which historical geography is opening doors into uncharted lives and unspoken histories

    Collateral-resistance to estrogen and HER-activated growth is associated with modified AKT, ERα and cell-cycle signaling in a breast cancer model

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    These studies were supported by grants from Cancer Research UK (C503/A5010 and C1938/A6769).Aim : A model of progressively endocrine-resistant breast cancer was investigated to identify changes that can occur in signaling pathways after endocrine manipulation. Methods : The MCF7 breast cancer model is sensitive to estrogens and anti-estrogens while variant lines previously derived from wild-type MCF7 are either relatively 17β-estradiol (E2)-insensitive (LCC1) or fully resistant to estrogen and anti-estrogens (LCC9). Results : In LCC1 and LCC9 cell lines, loss of estrogen sensitivity was accompanied by loss of growth response to transforming growth factor alpha (TGFα), heregulin-beta and pertuzumab. LCC1 and LCC9 cells had enhanced AKT phosphorylation relative to MCF7 which was reflected in downstream activation of phospho-mechanistic target of rapamycin (mTOR), phospho-S6, and phospho-estrogen receptor alpha Ser167 [ERα(Ser167)]. Both AKT2 and AKT3 were phosphorylated in the resistant cell lines, but siRNA knockdown suggested that all three AKT isoforms contributed to growth response. ERα(Ser118) phosphorylation was increased by E2 and TGFα in MCF7, by E2 only in LCC1, but by neither in LCC9 cells. Multiple alterations in E2-mediated cell cycle control were identified in the endocrine-resistant cell lines including increased expression of MYC, cyclin A1, cyclin D1, cyclin-dependent kinase 1 (CDK1), CDK2, and hyperphosphorylated retinoblastoma protein (ppRb), whereas p21 and p27 were reduced. Estrogen modulated expression of these regulators in MCF7 and LCC1 cells but not in LCC9 cells. Seliciclib inhibited CDK2 activation in MCF7 cells but not in resistant variants; in all lines, it reduced ppRb, increased p53 associated responses including p21, p53 up-regulated modulator of apoptosis (PUMA), and p53 apoptosis-inducing protein 1 (p53AIP1), inhibited growth, and produced G2/M block and apoptosis. Conclusions : Multiple changes occur with progression of endocrine resistance in this model with AKT activation contributing to E2 insensitivity and loss of ERα(Ser118) phosphorylation being associated with full resistance. Cell cycle regulation is modified in endocrine-resistant breast cancer cells, and seliciclib is effective in both endocrine-sensitive and resistant diseases.Publisher PDFPeer reviewe

    Gaping behaviour of Blue mussels (Mytilus edulis) in relation to freshwater runoff risks

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    Shellfish grown for food are vulnerable to environmental contamination, potentially rendering them unsafe for human consumption. Non-invasive gape (valve openness) sensing allows in-situ monitoring of bivalve shellfish behaviours, such as feeding, that can result in exposure to contaminated waters. Sensors were attached to Blue mussels and deployed for 10 days on natural mussel beds in Dundrum Bay, Northern Ireland. Data showed a tidally synchronous behaviour pattern of high openness at high water and vice versa. It is likely that this is, at least in part, due to extreme salinity variation (1.8–33.6) resulting from near total water exchange with each tide in the bay. This behaviour is likely to infer a degree of protection from contaminants during periods of low water, a time at which runoff-derived pollutants are most concentrated

    Managerial Work in a Practice-Embodying Institution - The role of calling, the virtue of constancy

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    What can be learned from a small scale study of managerial work in a highly marginal and under-researched working community? This paper uses the ‘goods-virtues-practices-institutions’ framework to examine the managerial work of owner-directors of traditional circuses. Inspired by MacIntyre’s arguments for the necessity of a narrative understanding of the virtues, interviews explored how British and Irish circus directors accounted for their working lives. A purposive sample was used to select subjects who had owned and managed traditional touring circuses for at least 15 years, a period in which the economic and reputational fortunes of traditional circuses have suffered badly. This sample enabled the research to examine the self-understanding of people who had, at least on the face of it, exhibited the virtue of constancy. The research contributes to our understanding of the role of the virtues in organizations by presenting evidence of an intimate relationship between the virtue of constancy and a ‘calling’ work orientation. This enhances our understanding of the virtues that are required if management is exercised as a domain-related practice
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