489 research outputs found

    Reliability of Sprint Acceleration Performance and Three Repetition Maximum Back Squat Strength in Hurling Players

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    The purpose of this study was to estimate the inter-day reliability of 5, 10 and 20-meter sprint time and three repetition maximum back squat strength in male hurling players. Eighteen male hurling players volunteered to participate and performed 20- meter sprint trials and a three repetition maximum back squat strength test at each test session, on three separate occasions, a minimum of 48 hours apart. Participants performed three sprints over 20-meters, including split times at 5 and 10-meters. The three repetition back squat strength test was performed after the sprint test. The results displayed acceptable levels of reliability for sprint performance times (Intra class correlation coefficient single measure range: 0.76-0.89; Coefficient of variance range: 1.0 – 2.0%) and absolute and relative three repetition maximum back squat strength (Intra class correlation coefficient single measure: 0.98; CV 0.8%). Furthermore, sprint performance times and three repetition maximum back squat strength measures estimated feasible minimum a priori sample sizes from limits of agreement (5-meter:0.01 ± 0.08 s; 10-meter:-0.01 ± 0.12; 20-meter:-0.007 ± 0.15s; three repetition maximum (kg): 1.11 ± 4.19kg; three repetition maximum (kg/BW): 0.01 ± 0.06) random error therefore showing acceptable reliability. Sprint performance over 5, 10 and 20-meters and three repetition maximum back squat strength are reliable measures in male hurling players and can be used to estimate feasible minimum a priori sample sizes for sport science research

    Tuneable separation of gold by selective precipitation using a simple and recyclable diamide

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    The separation of metals from electronic waste is an enduring technological and societal challenge, and new metal extraction, refining and recycling solutions are needed. Here the authors report a recyclable and tuneable chemical reagent that separates valuable metals such as gold by direct and selective precipitation from various acidic, mixed-metal solutions of relevance to extraction and recycling industries

    Challenges and Applications of Supramolecular Metalate Chemistry

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    While the supramolecular chemistry of simple anions is ubiquitous, the targeting and exploitation of their metal-containing relatives, the metalates, is less well understood. This mini review highlights the latest advances in this emergent area by discussing the supramolecular chemistry of metalates thematically, with a focus on the exploitation of metalates in a diversity of applications, including medical imaging and therapy, environmental remediation, molecular magnetism, catalysis, perovskite materials, and metal separations. The unifying features of these systems are identified with a view to allow the supramolecular chemist to target the unique material properties of the metalates, even in areas that are currently relatively immature.</p

    Reducing the Competition: A Dual-Purpose Ionic Liquid for the Extraction of Gallium from Iron Chloride Solutions

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    The separation of gallium from iron by solvent extraction from chloride media is challenging because the anionic chloridometalates, FeCl4&minus; and GaCl4&minus;, display similar chemical properties. However, we report here that the selective separation of gallium from iron in HCl solution can be achieved using the dual-purpose ionic liquid methyltrioctylammonium iodide in a solvent extraction process. In this case, the reduction of Fe3+ to Fe2+ by the iodide counterion was found to inhibit Fe transport, facilitating quantitative Ga extraction by the ionic liquid with minimal Fe extraction from 2 M HCl

    Understanding the recovery of rare-earth elements by ammonium salts

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    While the recovery of rare earth elements (REEs) from aqueous solution by ionic liquids (ILs) has been well documented, the metal compounds that are formed in the organic phase remain poorly characterized. Using spectroscopic, analytical, and computational techniques, we provide detailed chemical analysis of the compounds formed in the organic phase during the solvent extraction of REEs by [(n-octyl)3NMe][NO3] (IL). These experiments show that REE recovery using IL is a rapid process and that IL is highly durable. Karl-Fischer measurements signify that the mode of action is unlikely to be micellar, while ions of the general formula REE(NO3)4(IL)2&minus; are seen by negative ion electrospray ionization mass spectrometry. Additionally, variable temperature 139La nuclear magnetic resonance spectroscopy suggests the presence of multiple, low symmetry nitrato species. Classical molecular dynamics simulations show aggregation of multiple ILs around a microhydrated La3+ cation with four nitrates completing the inner coordination sphere. This increased understanding is now being exploited to develop stronger and more selective, functionalized ILs for REE recovery

    The robustness of carbon fibre members bonded to aluminium connectors in aerial delivery systems

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    In this paper a framework for robust design solution of an adhesively bonded joint between a composite material and an aluminum connector is developed. To this end, an approach has been developed to automate the process of robust design by linking Ansys workbench and an in-house MATLAB code. The model employed in this study investigated the possibility of joining composite materials to aluminum components which is a problematic process in terms of preparation, implementation, etc. Before designing such a join, it is necessary to fully understand the behaviour of the proposed aluminum connector with the carbon fibre member. To achieve this, the investigation of the adhesive layer’s behaviour and the uncertainties involved in such structures was identified. The behaviour of the adhesive between the carbon fibre composite and the aluminum connector was modelled based on the assumption that this layer acts as a “spring system” within a “cohesive” zone. Initially, the properties of Permabond ET5428 BLACK adhesive were used for validating the finite element model using the obtained test data. A robust design method is then employed to identify the right adhesive for the joint which not only maximizes the debonding force and sliding distance but is also robust with respect to the variation in its mechanical properties. A wide range of adhesive properties have been employed and a robust design technique based on uncertainty analysis is proposed

    Shape-Selective Supramolecular Capsules for Actinide Precipitation and Separation

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    Improving actinide separations is key to reducing barriers to medical and industrial actinide isotope production and to addressing the challenges associated with the reprocessing of spent nuclear fuel. Here, we report the first example of a supramolecular anion recognition process that can achieve this goal. We have designed a preorganized triamidoarene receptor that induces quantitative precipitation of the early actinides Th(IV), Np(IV), and Pu(IV) from industrially relevant conditions through the formation of self-assembled hydrogen-bonded capsules. Selectivity over the later An(III) elements is shown through modulation of the nitric acid concentration, and no precipitation of actinyl or transition-metal ions occurs. The Np, Pu, and Am precipitates were characterized structurally by single-crystal X-ray diffraction and reveal shape specificity of the internal hydrogen-bonding array for the encapsulated hexanitratometalates. This work complements ion-exchange resins for 5f-element separations and illustrates the significant potential of supramolecular separation methods that target anionic actinide species

    A Simple Supramolecular Approach to Recycling Rare Earth Elements

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    The rapid increase in demand for rare-earth elements reflects their crucial roles in climate critical technologies. However, the lack of simple solutions for the separation of these metals from waste materials and ores represents a significant barrier to sustainable and environmentally benign rare-earth production. We report the application of a supramolecular approach to this challenge, using a triamido-arene receptor to selectively precipitate f-elements through their encapsulation as hexanitratometalates. Single-step, near quantitative recovery of Nd/Pr directly from magnet scrap was observed without the need for pH adjustment or pretreatment of the acidic leach solution. The rare-earth nitrate was rapidly stripped from the host−guest precipitate with water and the receptor recycled for further use. Near quantitative and highly selective uptake of La−Nd and Th from lateritic rare-earth ores was also achieved with no uptake of any non-f-element. These results show that targeting f-element metalates in separations chemistry can deliver exceptional and unique selectivity that may have significant consequences in the sustainable production of the rare-earth elements
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