1,286 research outputs found

    Anion and solvent influences on the self-assembly of copper(I) coordination solids

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    The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file viewed on (November 8, 2006)Includes bibliographical references.Vita.Thesis (Ph. D.) University of Missouri-Columbia 2005.Dissertations, Academic -- University of Missouri--Columbia -- Chemistry.The investigation of solvent and anion influences on the self-assembly of copper(I) coordination solids are presented. As these extended solids vary in structural design as reactions conditions are varied, both those particular structural variances and the reaction conditions involved will be discussed. This presentation will be divided into four major sections. The first section covers an in-depth look at those structural variances found among the copper(I) coordination solids synthesized using 4,4'-bipyridine with refined synthesis and related structures. This entire system is thoroughly examined in order to identify all possible structural variances resulting from the implementation of a specific set of reaction variables, specifically the identity of both anion and reaction solvent used. The second and third parts will look closer at the self-assembly reaction mechanism as synthetic intermediate structures are presented and analyzed in relation to the above-mentioned structures. Each structure presented offers information in regards to the role the anion or solvent play in the self-assembly reactions The final section deals with similar reactions using the pyrimidine ligand. Several structures presented here suggests that anion templation plays a major role in the extended solids formation. This section concludes with a practical application of these materials as a study of selective anion exchange with a large cavity Cu(I) coordination solid is presented

    Study of aluminoborane compound AlB_4H_(11) for hydrogen storage

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    Aluminoborane compounds AlB_4H_(11), AlB_5H_(12), and AlB_6H_(13) were reported by Himpsl and Bond in 1981, but they have eluded the attention of the worldwide hydrogen storage research community for more than a quarter of a century. These aluminoborane compounds have very attractive properties for hydrogen storage: high hydrogen capacity (i.e., 13.5, 12.9, and 12.4 wt % H, respectively) and attractive hydrogen desorption temperature (i.e., AlB_4H_(11) decomposes at ~125 °C). We have synthesized AlB_4H_(11) and studied its thermal desorption behavior using temperature-programmed desorption with mass spectrometry, gas volumetric (Sieverts) measurement, infrared (IR) spectroscopy, and solid state nuclear magnetic resonance (NMR). Rehydrogenation of hydrogen-desorbed products was performed and encouraging evidence of at least partial reversibility for hydrogenation at relatively mild conditions is observed. Our chemical analysis indicates that the formula for the compound is closer to AlB_4H_(12) than AlB_4H_(11)

    DNA sequences of Alu elements indicate a recent replacement of the human autosomal genetic complement

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    DNA sequences of neutral nuclear autosomal loci, compared across diverse human populations, provide a previously untapped perspective into the mode and tempo of the emergence of modern humans and a critical comparison with published clonally inherited mitochondrial DNA and Y chromosome measurements of human diversity. We obtained over 55 kilobases of sequence from three autosomal loci encompassing Alu repeats for representatives of diverse human populations as well as orthologous sequences for other hominoid species at one of these loci. Nucleotide diversity was exceedingly low. Most individuals and populations were identical. Only a single nucleotide difference distinguished presumed ancestral alleles from descendants. These results differ from those expected if alleles from divergent archaic populations were maintained through multiregional continuity. The observed virtual lack of sequence polymorphism is the signature of a recent single origin for modern humans, with general replacement of archaic populations

    Successful Establishment of Oversown Chicory and Plantain on Uncultivatable Hill Country

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    All-year grazing of livestock on steep, non-arable hill country (\u3e 20o slope angle, \u3c 1,000 m elevation) is a significant feature of New Zealand agriculture. Hill country pastures are in various states of improvement depending on factors such as extent of subdivision, fertiliser inputs, plant species introduction, and grazing management. Numerous introduced grass, legume and herb species are available to match the many micro-sites in steep hill country (Kemp et al. 1999). There has been increasing use of the perennial herbs chicory (Chicorium intybus L.) and plantain (Plantago lanceolata L.) in seed mixtures used on a range of topographies, mostly flat to undulating terrain. Advantages of these species include tolerance of drought and high summer temperatures, highly palatable foliage, enhanced mineral content, and high animal growth rates (Stewart 1996; Li and Kemp 2005). Farmers have sown these species on hill country but there is negligible information on their establishment in such landscapes. As part of a large, New Zealand-wide programme to increase pasture productivity on non-arable hill country through new germplasm introduction, chicory and plantain were included in a seed mixture broadcast-sown at a range of sites. This paper reports on the seedling establishment of these two species

    Review of high-contrast imaging systems for current and future ground- and space-based telescopes I. Coronagraph design methods and optical performance metrics

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    The Optimal Optical Coronagraph (OOC) Workshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas. In this first installment of a series of three papers summarizing the outcomes of the OOC workshop, we present an overview of design methods and optical performance metrics developed for coronagraph instruments. The design and optimization of coronagraphs for future telescopes has progressed rapidly over the past several years in the context of space mission studies for Exo-C, WFIRST, HabEx, and LUVOIR as well as ground-based telescopes. Design tools have been developed at several institutions to optimize a variety of coronagraph mask types. We aim to give a broad overview of the approaches used, examples of their utility, and provide the optimization tools to the community. Though it is clear that the basic function of coronagraphs is to suppress starlight while maintaining light from off-axis sources, our community lacks a general set of standard performance metrics that apply to both detecting and characterizing exoplanets. The attendees of the OOC workshop agreed that it would benefit our community to clearly define quantities for comparing the performance of coronagraph designs and systems. Therefore, we also present a set of metrics that may be applied to theoretical designs, testbeds, and deployed instruments. We show how these quantities may be used to easily relate the basic properties of the optical instrument to the detection significance of the given point source in the presence of realistic noise.Comment: To appear in Proceedings of the SPIE, vol. 1069

    Circulating endocannabinoids during hematopoietic stem cell transplantation: A pilot study

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    AbstractObjectiveHematopoietic stem cell transplantation (HCT) is a stressful and rigorous medical procedure involving significant emotional and immune challenges. The endocannabinoid (eCB) signaling system is involved in regulation of both the immune system and emotional reactivity, yet little is known about its function during HCT. We investigated the role of the eCB signaling system in a group of HCT recipients.MethodsA total of 19 HCT recipients were enrolled and provided psychosocial data and blood samples at three peri-transplant time points: prior to transplant, hospital discharge, and approximately 100 days post-transplant. Psychosocial factors, inflammatory molecules, and the eCBs were determined and assessed for changes over this period and association with each other.ResultsHCT recipients demonstrated significant changes over the peri-transplant period in inflammatory molecules and psychosocial functioning, but not in circulating concentrations of the eCBs. Associations among these variables were most likely to be present pre-transplant and least likely to be present immediately post-transplant, with depressive symptoms and inflammation most significantly associated. The eCB 2-arachidonoylglycerol (2-AG) was significantly, positively associated with both interleukin (IL)-6 and C-reactive protein (CRP) and negatively associated with depressive symptoms.ConclusionsThe eCB signaling system may have alternative sources and regulatory mechanisms in addition to the immune system. Given the significant associations with inflammatory molecules and depressive symptoms in the peri-transplant period, it is important to better understand this system and its potential implications in the setting of complex and stressful medical procedures such as HCT

    W(h)ither the academy? An exploration of the role of university social work in shaping the future of social work in Europe

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    A controversial proposal to pilot the training of child protection social workers through an intensive work-based route in England is being supported and funded by the UK Government. Frontline, the brainchild of a former teacher, locates social work training within local authorities (‘the agency’) rather than university social work departments (‘the academy’) and has stimulated debate amongst social work academics about their role in shaping the direction of the profession. As a contribution to this debate, this paper explores the duality of social work education, which derives its knowledge from both the academic social sciences and the experience of practice within social work agencies. While social work education has traditionally been delivered by the academy, this paper also explores whether the delivery of training in the allied professions of probation and nursing by ‘the agency’ is equally effective. Finally, this paper explores the Helsinki model which achieves a synergy of ‘academy’ and ‘agency’. It suggests that there are alternative models of social work education, practice and research which avoid dichotomies between the ‘academy’ and the ‘agency’ and enable the profession to be shaped by both social work academics and practitioners
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