Aberration corrected (S)TEM of Nanoparticle and Atomically Dispersed Catalysts

The field of catalysis is of paramount importance. Catalysts allow chemical reactions to be carried out with lower energy than otherwise possible. They play an important role in the reduction of harmful emissions from todays vehicles and are crucial for designing alternative energy sources for tomorrows vehicles. Many catalysts take the form of nano-sized particles which brings about challenges for their design and characterisation. In this thesis, aberration corrected electron microscopy is utilised for atomically resolved investigations of the structure of catalytically active nanoparticles as freshly produced and to provide insights of deactivation in treated and used catalysts. Platinum and palladium nanoparticles are used for the reduction of harmful emissions from diesel car exhausts. Here, fresh insights are provided into the loss of activity in genuine road aged diesel oxidation catalysts. They include the segregation of alloys in the bimetallic variant in which the less active palladium moves to the surface where it can more easily form an oxide. Nano-beam diffraction was used in this study as well as for a model platinum system. The seldom used nano-beam diffraction technique was employed to provide additional structural information on very small nanoparticles, including those that contained defects. Using nano-beam diffraction, no oxides were found in the platinum model catalyst and loss of activity was due to sintering. Ex-situ studies can only provide before and after information. Here, results from the latest developments in environmental scanning transmission electron microscopy are presented with model catalysts, namely atomically dispersed platinum and palladium. Single atoms of the metals were observed at temperatures as high as 500 degree-celsius and in O2 which represents the current state of the art in this field. The limitations of the Z contrast technique is also investigated for heavy atoms located on heavy supports, such as atomically dispersed gold on ceria. Intricacies in the reduction of Co3O4 to CoO are provided using in-situ transmission electron microscopy in H2 at elevated temperatures. A new fuse wire like transformation is seen in large crystals in addition to dislocations to accomodate strain into the crystal structure

Gryphon: An Information Flow Based Approach to Message Brokering

Gryphon is a distributed computing paradigm for message brokering, which is the transferring of information in the form of streams of events from information providers to information consumers. This extended abstract outlines the major problems in message brokering and Gryphon's approach to solving them.Comment: Two page extended abstrac

The development of a novel standardisation-customisation continuum

Published work on product-oriented customisation lacks clarity in establishing how it is characterised, how it is bounded, and how one would define increasing levels of customisation. This paper describes the development of a standardisation-customisation (S-C) continuum which consists of 13 distinct intervals, starting with “standardisation”, or absence of customisation and ending with “evolution customisation”, or absence of standardisation. Each interval is defined using nine characteristics that collectively define the boundaries of the intervals within the continuum. Analysis using a randomly selected sample of products from a range of industries has demonstrated the continuum’s capability for distinguishing the associated level of S-C. Furthermore, no industry investigated develops products at each level of S-C, however, when combined all industries do. The number of possible levels of S-C tends to depend on the product’s complexity and number of components. The continuum framework clarifies the concept of customisation, provides a scale for determining the product’s customisation and supports the analysis of markets and industries against S-C

The potential of the co-operative form for farmers' markets in Ireland: Some lessons from the USA and UK

One of the most important developments in small-scale agriculture and in local food retailing in the last decade has been the emergence of a new generation of farmers’ markets in countries such as Ireland, the USA, the UK, New Zealand and Australia. Farmers’ markets are now a significant alternative source of sales, distribution and marketing for many small scale producers and a valuable source of fresh, local and specialist produce for growing numbers of consumers. This paper presents findings from the initial stages of a large-scale study which seeks to establish how farmers’ markets in Ireland can best be structured and organised to increase the competitiveness and sustainability of small farmers and to strengthen farmer influence and control in the marketplace. The research is particularly concerned with examining the potential of formal co-operative structures, which though relatively common in farmers’ markets in the US and the UK, remain largely unexplored in an Irish context. While ongoing extensive quantitative and qualitative research on all Irish farmers’ markets is the primary focus of the research, field visits to markets and key informants in the US and UK have also been conducted and completed. The findings from the latter research – and more specifically, their potential relevance to Irish farmers’ markets at their current stage of development – are the subject of this paper

Single Atom Dynamics in Chemical Reactions

Many heterogeneous chemical reactions involve gases catalyzed over solid surfaces at elevated temperatures and play a critical role in the production of energy, healthcare, pollution control, industrial products, and food. These catalytic reactions take place at the atomic level, with active structures forming under reaction conditions. A fundamental understanding of catalysis at the single atom resolution is therefore a major advance in a rational framework upon which future catalytic processes can be built. Visualization and analysis of gas-catalyst chemical reactions at the atomic level under controlled reaction conditions are key to understanding the catalyst structural evolution and atomic scale reaction mechanisms crucial to the performance and the development of improved catalysts and chemical processes. Increasingly, dynamic single atoms and atom clusters are believed to lead to enhanced catalyst performance, but despite considerable efforts, reaction mechanisms at the single atom level under reaction conditions of gas and temperature are not well understood. The development of the atomic lattice resolution environmental transmission electron microscope (ETEM) by the authors is widely used to visualize gas–solid catalyst reactions at this atomic level. It has recently been advanced to the environmental scanning TEM (ESTEM) with single atom resolution and full analytical capabilities. The ESTEM employs high-angle annular dark-field imaging where intensity is approximately proportional to the square of the atomic number (Z). In this Account, we highlight the ESTEM development also introduced by the authors for real time in situ studies to reliably discern metal atoms on lighter supports in gas and high temperature environments, evolving oxide/metal interfaces, and atomic level reaction mechanisms in heterogeneous catalysts more generally and informatively, with utilizing the wider body of literature. The highlights include platinum/carbon systems of interest in fuel cells to meet energy demands and reduce environmental pollution, in reduction/oxidation (redox) mechanisms of copper and nickel nanoparticles extensively employed in catalysis, electronics, and sensors, and in the activation of supported cobalt catalysts in Fischer–Tropsch (FT) synthesis to produce fuels. By following the dynamic reduction process at operating temperature, we investigate Pt atom migrations from irregular nanoparticles in a carbon supported platinum catalyst and the resulting faceting. We outline the factors that govern the mechanism involved, with the discovery of single atom interactions which indicate that a primary role of the nanoparticles is to act as reservoirs of low coordination atoms and clusters. This has important implications in supported nanoparticle catalysis and nanoparticle science. In copper and nickel systems, we track the oxidation front at the atomic level as it proceeds across a nanoparticle, by directly monitoring Z-contrast changes with time and temperature. Regeneration of deactivated catalysts is key to prolong catalyst life. We discuss and review analyses of dynamic redox cycles for the redispersion of nickel nanoparticles with single atom resolution. In the FT process, pretreatment of practical cobalt/silica catalysts reveals higher low-coordination Co0 active sites for CO adsorption. Collectively, the ESTEM findings generate structural insights into catalyst dynamics important in the development of efficient catalysts and processes

Establishing the baseline in groundwater chemistry in connection with shale-gas exploration: Vale of Pickering, UK

The baseline chemistry of groundwater from two aquifers in the Vale of Pickering, North Yorkshire, has been investigated ahead of a proposal to explore for shale gas, planning permission for which has recently been granted. Groundwater in a shallow aquifer including Quaternary and/or Jurassic Kimmeridge Clay deposits shows compositions distinct from a Corallian (Jurassic) Limestone aquifer, reflecting different lithologies and hydrogeological conditions. Corallian groundwaters along the margins of the vale are controlled by reaction with carbonate, with redox conditions varying according to degree of aquifer confinement. Superficial aquifer groundwaters are confined and strongly reducing, with some observed high concentrations of dissolved CH4 (up to 37 mg/L; Feb 2016 data). This appears to be of mixed biogenic-thermogenic origin but further work is needed to determine whether the source includes a deeper hydrocarbon reservoir contributing via fractures, or a shallower source in the Quaternary or Kimmeridge sediments. The data show a shallow aquifer with a high-CH4 baseline which pre-dates any shale-gas activity

Phosphorylation of synaptic GTPase-activating protein (synGAP) by polo-like kinase (Plk2) alters the ratio of its GAP activity toward HRas, Rap1 and Rap2 GTPases

SynGAP is a Ras and Rap GTPase-activating protein (GAP) found in high concentration in the postsynaptic density (PSD) fraction from mammalian forebrain where it binds to PDZ domains of PSD-95. Phosphorylation of pure recombinant synGAP by Ca^(2+)/calmodulin-dependent protein kinase II (CaMKII) shifts the balance of synGAP's GAP activity toward inactivation of Rap1; whereas phosphorylation by cyclin-dependent kinase 5 (CDK5) has the opposite effect, shifting the balance toward inactivation of HRas. These shifts in balance contribute to regulation of the numbers of surface AMPA receptors, which rise during synaptic potentiation (CaMKII) and fall during synaptic scaling (CDK5). Polo-like kinase 2 (Plk2/SNK), like CDK5, contributes to synaptic scaling. These two kinases act in concert to reduce the number of surface AMPA receptors following elevated neuronal activity by tagging spine-associated RapGAP protein (SPAR) for degradation, thus raising the level of activated Rap. Here we show that Plk2 also phosphorylates and regulates synGAP. Phosphorylation of synGAP by Plk2 stimulates its GAP activity toward HRas by 65%, and toward Rap1 by 16%. Simultaneous phosphorylation of synGAP by Plk2 and CDK5 at distinct sites produces an additive increase in GAP activity toward HRas (∼230%) and a smaller, non-additive increase in activity toward Rap1 (∼15%). Dual phosphorylation also produces an increase in GAP activity toward Rap2 (∼40–50%), an effect not produced by either kinase alone. As we previously observed for CDK5, addition of Ca^(2+)/CaM causes a substrate-directed doubling of the rate and stoichiometry of phosphorylation of synGAP by Plk2, targeting residues also phosphorylated by CaMKII. In summary, phosphorylation by Plk2, like CDK5, shifts the ratio of GAP activity of synGAP to produce a greater decrease in active Ras than in active Rap, which would produce a shift toward a decrease in the number of surface AMPA receptors in neuronal dendrites

Antibiotic Treatment of Suspected and Confirmed Neonatal Sepsis Within 28 Days of Birth: A Retrospective Analysis

Neonatal sepsis causes significant mortality and morbidity worldwide. Diagnosis is usually confirmed via blood culture results. Blood culture sepsis confirmation can take days and suffer from contamination and false negatives. Empiric therapy with antibiotics is common. This study aims to retrospectively describe and compare treatments of blood culture-confirmed and unconfirmed, but suspected, sepsis within the University of Utah Hospital system. Electronic health records were obtained from 1,248 neonates from January 1, 2006, to December 31, 2017. Sepsis was categorized into early-onset (≤3 days of birth, EOS) and late-onset (\u3e3 and ≤28 days of birth, LOS) and categorized as culture-confirmed sepsis if a pathogen was cultured from the blood and unconfirmed if all blood cultures were negative with no potentially contaminated blood cultures. Of 1,010 neonates in the EOS cohort, 23 (2.3%) were culture-confirmed, most with Escherichia coli (42%). Treatment for unconfirmed EOS lasted an average of 6.1 days with primarily gentamicin and ampicillin while confirmed patients were treated for an average of 12.3 days with increased administration of cefotaxime. Of 311 neonates in the LOS cohort, 62 (20%) were culture-confirmed, most culturing coagulase negative staphylococci (46%). Treatment courses for unconfirmed LOS lasted an average of 7.8 days while confirmed patients were treated for an average of 11.4 days, these patients were primarily treated with vancomycin and gentamicin. The use of cefotaxime for unconfirmed EOS and LOS increased throughout the study period. Cefotaxime administration was associated with an increase in neonatal mortality, even when potential confounding factors were added to the logistic regression model (adjusted odds ratio 2.8, 95%CI [1.21, 6.88], p = 0.02). These results may not be generalized to all hospitals and the use of cefotaxime may be a surrogate for other factors. Given the low rate of blood culture positive diagnosis and the high exposure rate of empiric antibiotics, this patient population might benefit from improved diagnostics with reevaluation of antibiotic use guideline