Diamond Light Source (United Kingdom)

About: Diamond Light Source (United Kingdom) is a facility organization based out in Didcot, United Kingdom. It is known for research contribution in the topics: Geology & Chemistry. The organization has 24 authors who have published 12 publications receiving 90 citations.

Characterization of the high-pressure and high-temperature phase diagram and equation of state of chromium

Abstract: The high-pressure and high-temperature phase diagram of chromium has been investigated both experimentally (in situ), using a laser-heated diamond-anvil cell technique coupled with synchrotron powder X-ray diffraction, and theoretically, using ab initio density-functional theory simulations. In the pressure-temperature range covered experimentally (up to 90 GPa and 4500 K, respectively) only the solid body-centred-cubic and liquid phases of chromium have been observed. Experiments and computer calculations give melting curves in agreement with each other that can both be described by the Simon-Glatzel equation [Formula: see text]. In addition, a quasi-hydrostatic equation of state at ambient temperature has been experimentally characterized up to 131 GPa and compared with the present simulations. Both methods give very similar third-order Birch-Murnaghan equations of state with bulk moduli of 182-185 GPa and respective pressure derivatives of 4.74-5.15. According to the present calculations, the obtained melting curve and equation of state are valid up to at least 815 GPa, at which pressure the melting temperature is 9310 K. Finally, from the obtained results, it was possible to determine a thermal equation of state of chromium valid up to 65 GPa and 2100 K.

A New Route for De-carboxylation of Lactones over Zn/ZSM-5: Elucidation of Structure and Molecular Interactions

Abstract: Here, we report a catalytic process of decarboxylating gamma-valerolactone, GVL (the biomass derived lactone as an example) over Zn/ZSM-5 to butene, followed by aromatization at high yield with co-feed water. Evaluation of catalytic performance at prolonged time shows that water molecule is essential in maintaining the decarboxylation/ aromatization activity without rapid deactivation. Synchrotron X-ray diffraction and Rietveld refinement are then used to elucidate the adsorbed structures of GVL and immobilized Zn-species with the support of EXAFS and NMR. A new route of cooperative hydrolysis of GVL by framework Zn-OH and Bronsted acid sites to butene and then to aromatics is for the first time demonstrated. The structures and fundamental pathways for nucleophilic attack of terminal Zn-OH site are comparable to that of reported Zn-containing enzymes in biological systems.

Development of synchrotron pink beam x-ray grating interferometer at the Diamond Light source I13-2 beamline

Abstract: X-ray Grating Talbot Interferometer (XGTI) is already routinely used for quantitative phase contrast imaging of soft tissue samples. XGTI can be realized using various measurement techniques, depending on the X-ray source used, the required spatial resolution and the speed of acquisition. The phase-stepping measurement technique, which is commonly used for XGTI data acquisition, needs multiple acquisitions for a single projection. For fast imaging the Moire technique, a single-shot technique, is often preferred. However, it requires two gratings which increases the dose on the sample. We have therefore examined the Spatial Harmonic Imaging (SHI) technique which is low-dose and single-shot, using the I13-2 Diamond-Manchester Beamline at Diamond Light Source (DLS). The DLS I13-2 beamline is equipped with a Double Crystal Monochromator (DCM) and a Multi-Layer Monochromator (MLM) to deliver monochromatic beam, which work at the energy bandwidths (ΔE/E) of 10-4 and 10-2, respectively. However, the disadvantage of using these monochromators, especially for fast imaging, is loss of X-ray flux. It has already been shown that XGTI can work with an energy bandwidth (ΔE/E) of 10-1. Our aim is to develop a single phase grating interferometer with pink beam from an undulator source, with X-ray mirror optics and multiple absorption filters, to obtain maximum possible flux with sufficient coherence and monochromaticity. We demonstrate performance with optimized beamline parameters for a photon energy of 15 keV with some demonstrative image reconstructions.

Comparing the accuracy of intraoral scanners, using advanced micro computed tomography

Abstract: Intraoral scanners have been gaining importance in dental offices. The technology has become a valuable and economically reasonable alternative to conventional silicone impressions and the conventional plaster casts because of the reduced treatment time and the sufficient precision achieved. The required precision of the dental prostheses depends on the clinical needs. For the production of working models, the tolerable inaccuracy is relatively large. Especially for crowns, bridges and larger dental prostheses, which include several teeth over the dental arch, however, extra work is often performed, that presumably caused by the limited accuracy of intraoral scanners. Therefore, the paper deals with the detailed evaluation of selected, commercially available intraoral scanner systems. For this purpose, we have designed and realized a model of a full arch upper jaw on the basis of clinically relevant imaging data. As well-defined references, we have incorporated cylinders with a diameter of 4 mm. This standard to be used as reference, was quantitatively characterized by four independent measurements using the advanced CT-system phoenix nanotom® m (GE Sensing & Inspection Technologies GmbH, Wunstorf, Germany) with a pixel size of 35 μm. The standard was also scanned using five commercially available intraoral scanners. In order to compare the accuracy of the ten measurements per scanner, the data were matched to the standard. Their displacements were made visible with GOM Inspect (GOM GmbH Braunschweig, Germany). Applying the same approach, we have analyzed the accuracy of two three-dimensionally printed dental models by the stereolithography printers Form 2, Formlabs Inc., Somerville MA, USA). The results demonstrate the currently possible level of precision by the selected intraoral scanners. They differ, however, not only in scanning time necessary and the ease of handling, but also in reachable accuracy. The precision ranged from (35 ± 5) μm (TRIOS® 3) to (97 ± 22) μm (EmeraldTM). The largest deviations to the standard were found in the transversal plane (412 ± 247) μm (Medit i500). The combination of advanced conventional microCT and adequate software for quantitative analysis permits a detailed evaluation of the performance of the currently available intraoral scanners.

TIM: modelling pathways to meet Ireland's long-term energy system challenges with the TIMES-Ireland Model (v1.0)

Abstract: Abstract. Ireland has significantly increased its climate mitigation ambition, with a recent government commitment to reduce greenhouse gases by an average of 7 % yr−1 in the period to 2030 and a net-zero target for 2050, underpinned by a series of 5-year carbon budgets. Energy systems optimisation modelling (ESOM) is a widely used tool to inform pathways to address long-term energy challenges. This article describes a new ESOM developed to inform Ireland's energy system decarbonisation challenge. The TIMES-Ireland Model (TIM) is an optimisation model of the Irish energy system, which calculates the cost-optimal fuel and technology mix to meet future energy service demands in the transport, buildings, industry, and agriculture sectors, while respecting constraints in greenhouse gas emissions, primary energy resources, and feasible deployment rates. TIM is developed to take into account Ireland's unique energy system context, including a very high potential for offshore wind energy and the challenge of integrating this on a relatively isolated grid, a very ambitious decarbonisation target in the period to 2030, the policy need to inform 5-year carbon budgets to meet policy targets, and the challenge of decarbonising heat in the context of low building stock thermal efficiency and high reliance on fossil fuels. To that end, model features of note include future-proofing with flexible temporal and spatial definitions, with a possible hourly time resolution, unit commitment and capacity expansion features in the power sector, residential and passenger transport underpinned by detailed bottom-up sectoral models, cross-model harmonisation, and soft-linking with demand and macro models. The paper also outlines a priority list of future model developments to better meet the challenge of deeply decarbonising energy supply and demand, taking into account the equity, cost-effectiveness, and technical feasibility. To support transparency and openness in decision-making, TIM is available to download under a Creative Commons licence.