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14,074 items found (0 items not approved), displaying 51 to 60.[First/Prev] 2, 3, 4, 5, 6, 7, 8, 9 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I12-JEEP: Joint Engineering, Environmental and Processing	Synchrotron imaging derived relationship between process parameters and build quality for directed energy deposition additively manufactured IN718 S. V. Notley , Y. Chen , N. A. Thacker , P. D. Lee , G. Panoutsos Additive Manufacturing Letters volume 861 DOI: 10.1016/j.addlet.2023.100137 Diamond Proposal Number(s): [20096] Open Access Show Abstract ▼ Abstract: Laser additive manufacturing is transforming several industrial sectors, especially the directed energy deposition process. A key challenge in the widespread uptake of this emerging technology is the formation of undesirable microstructural features such as pores, cracks, and large epitaxial grains. The trial and error approach to establish the relationship between process parameters and material properties is problematic due to the transient nature of the process and the number of parameters involved. In this work, the relationship between process parameters, melt pool geometry and quality of build measures, using directed energy deposition additive manufacturing for IN718, is quantified using neural networks as generalised regressors in a statistically robust manner. The data was acquired using in-situ synchrotron x-ray imaging providing unique and accurate measurements for our analysis. An analysis of the variations across repeated measurements show heteroscedastic error characteristics that are accounted for using a principled nonlinear data transformation method. The results of the analysis show that surface roughness correlates with melt pool geometry while the track height directly correlates with process parameters indicating a potential to directly control efficiency and layer thickness while independently minimising surface roughness.	Mar 2023
I21-Resonant Inelastic X-ray Scattering (RIXS)	Evolution of orbital excitations from insulating to superconducting MgTi2O4 films Qizhi Li , Abhishek Nag , Xiquan Zheng , Fucong Chen , Jie Yuan , Kui Jin , Yi Lu , Ke-Jin Zhou , Yingying Peng Physical Review B 107 DOI: 10.1103/PhysRevB.107.L121108 Show Abstract ▼ Abstract: Spinel oxides are well-known functional materials but rarely show superconductivity. Recently, emergent superconductivity was discovered in MgTi 2 O 4 , which is attributed to the increase of electron doping and the suppression of orbital order. Here, we utilized Ti L -edge resonant inelastic x-ray scattering to study the orbital excitations in superconducting (SC) and insulating MgTi 2 O 4 films. We find that the spectral weight of orbital excitations is enhanced and the energy of t 2 g intraband excitation is softened in the SC film compared to the insulating one, suggesting higher electron doping and a suppressed orbital order gap in the SC sample. These observations were further supported by our multiplet calculations using the minimal two-site model. Our results provide spectroscopic evidence for the competition between orbital order and superconductivity in MgTi 2 O 4 and shed light on searching for novel superconductors in spinel oxides.	Mar 2023
I22-Small angle scattering & Diffraction	Structuring supramolecular hyaluronan hydrogels via peptide self-assembly for modulating the cell microenvironment Yichen Yuan , Yejiao Shi , Jayati Banerjee , Amin Sadeghpour Dilmaghani , Helena S. Azevedo Materials Today Bio 12 DOI: 10.1016/j.mtbio.2023.100598 Diamond Proposal Number(s): [25037] Open Access Show Abstract ▼ Abstract: The use of synthetic extracellular matrices (ECMs) in fundamental in vitro cell culture studies has been instrumental for investigating the interplay between cells and matrix components. To provide cells with a more native environment in vitro, it is desirable to design matrices that are biomimetic and emulate compositional and structural features of natural ECMs. Here, the supramolecular fabrication of peptide-hyaluronan (HA) hydrogels is presented as promising ECM surrogates, combining HA and rationally designed cationic amphipatic peptides [(KI)nK, lysine (K), isoleucine (I), n = 2–6] whose mechanical properties and microstructure are tunable by the peptide sequence. (KI)nK peptides adopt β-sheet configuration and self-assemble into filamentous nanostructures triggered by pH or ionic strength. The self-assembly propensity of (KI)nK peptides increases with the sequence length, forming single phase hydrogels (shorter peptides) or with phase separation (longer peptides) in presence of the anionic polyelectrolyte HA through electrostatic complexations. The gel phase formed in (KI)nK-HA complexes exhibits viscoelastic behavior and triggers the formation of human mesenchymal stem cell (MSC) spheroids which disassemble over the time. It is anticipated that these (KI)nK-HA hydrogels with tunable physical and biochemical properties offer a promising platform for in vitro applications and in stem cell therapy.	Mar 2023
I18-Microfocus Spectroscopy	Selenium uptake from livestock pasture extremely enriched in selenium, molybdenum and uranium: a field and X-ray absorption study Shauna L. Mcloughlin , Richard A. D. Pattrick , J. Frederick W. Mosselmans , Joe Kelleher , Bart E. Van Dongen Soil Systems 7 DOI: 10.3390/soilsystems7010024 Diamond Proposal Number(s): [15475, 15215, 12700] Open Access Show Abstract ▼ Abstract: The agricultural soils of West Limerick, Ireland, contain very localised, extremely high natural Se concentrations that reach levels that are very toxic to grazing livestock. The Carboniferous shales that formed in anoxic deep-water marine environments are the source of the selenium, which, along with the other redox-sensitive elements of molybdenum, uranium, arsenic and vanadium, were mobilised and reprecipitated in post-glacial anoxic marshes. The result has been a history of selenosis and molybdenosis in livestock in this important dairy province. Soils collected at 10–20 cm from five different agricultural sites were analysed, and all yielded concentrations greatly in excess of the safe Se limits of 3–10 mg kg−1; the highest value recorded was 1265.8 mg kg−1 Se. The highest recorded value for Mo in these soils was 1627.5 mg kg−1, and for U, 658.8 mg kg−1. There was a positive correlation between Se, Mo U and organic matter in the soils. Analysis of non-accumulator pasture grasses (Lolium perenne (perennial ryegrass), Festuca arundinacea (tall fescue), Dactylis glomerata (cocksfoot) and Phleum pretense (timothy grass)) revealed the shoot/leaf to contain up to 78.05 mg kg−1 Se while Trifolium repens (white clover) leaves contained 296.15 mg kg−1 Se. An in situ growing experiment using the Se accumulator species Brassica oleracea revealed 971.2 mg kg−1 Se in the leaves of premier kale, which also contained 1000.4 mg kg−1 Mo. Translocation factors (TFs) were generally higher for Mo than Se across all plant species. Combined X-ray absorption near edge spectroscopy (XANES) with micro-X-ray fluorescence (μ-XRF) showed the Se was present in the soil predominantly as the reduced immobile phase, elemental Se (Se0), but also as bioavailable organoselenium species, mainly selenomethionine (SeMet). SeMet was also the main species identified within both the Se non-accumulator and Se accumulator plants. The Se soil–plant system in West Limerick is dominated by SeMet, and uptake into the cattle pasture results in selenosis in the grazing dairy herds. The hyperaccumulating Brassica oleracea species could be used to extract both the Se and Mo to reduce the toxicity of the blighted fields.	Mar 2023
I04-Macromolecular Crystallography	Diversification in the inositol tris/tetrakisphosphate kinase (ITPK) family: crystal structure and enzymology of the outlier AtITPK4 Hayley Whitfield , Sining He , Yinghong Gu , Colleen Sprigg , Hui-Fen Kuo , Tzyy-Jen Chiou , Andrew M. Riley , Barry V. L. Potter , Andrew M. Hemmings , Charles A. Brearley Biochemical Journal DOI: 10.1042/BCJ20220579 Diamond Proposal Number(s): [18565] Open Access Show Abstract ▼ Abstract: Myo-inositol tris/tetrakisphosphate kinases (ITPKs) catalyze diverse phosphotransfer reactions with myo-inositol phosphate and myo-inositol pyrophosphate substrates. However, the lack of structures of nucleotide-coordinated plant ITPKs thwarts a rational understanding of phosphotransfer reactions of the family. Arabidopsis possesses a family of four ITPKs of which two isoforms, ITPK1 and ITPK4, control inositol hexakisphosphate and inositol pyrophosphate levels directly or by provision of precursors. Here, we describe the specificity of Arabidopsis ITPK4 to pairs of enantiomers of diverse inositol polyphosphates and show how substrate specificity differs from Arabidopsis ITPK1. Moreover, we provide a description of the crystal structure of ATP-coordinated AtITPK4 at 2.11 Å resolution that along with description of the enantiospecificity of the enzyme affords a molecular explanation for the diverse phosphotransferase activity of this enzyme. That Arabidopsis ITPK4 has a Km for ATP in the tens of micromolar range, potentially explains how, despite the large-scale abolition of InsP6, InsP7 and InsP8 synthesis in Atitpk4 mutants, Atitpk4 lacks the phosphate starvation responses of Atitpk1 mutants. We further demonstrate that Arabidopsis ITPK4 and its homologs in other plants possess an N-terminal haloacid dehalogenase-like fold not previously described. The structural and enzymological information revealed will guide elucidation of ITPK4 function in diverse physiological contexts, including InsP8-dependent aspects of plant biology.	Mar 2023
B21-High Throughput SAXS	The dynamic nature of netrin-1 and the structural basis for glycosaminoglycan fragment-induced filament formation Markus Meier , Monika Gupta , Serife Akgül , Matthew Mcdougall , Thomas Imhof , Denise Nikodemus , Raphael Reuten , Aniel Moya-Torres , Vu To , Fraser Ferens , Fabian Heide , Gay P. Padilla-Meier , Philipp Kukura , Wenming Huang , Birgit Gerisch , Matthias Mörgelin , Kate Poole , Adam Antebi , Manuel Koch , Jörg Stetefeld Nature Communications 14 DOI: 10.1038/s41467-023-36692-w Open Access Show Abstract ▼ Abstract: Netrin-1 is a bifunctional chemotropic guidance cue that plays key roles in diverse cellular processes including axon pathfinding, cell migration, adhesion, differentiation, and survival. Here, we present a molecular understanding of netrin-1 mediated interactions with glycosaminoglycan chains of diverse heparan sulfate proteoglycans (HSPGs) and short heparin oligosaccharides. Whereas interactions with HSPGs act as platform to co-localise netrin-1 close to the cell surface, heparin oligosaccharides have a significant impact on the highly dynamic behaviour of netrin-1. Remarkably, the monomer-dimer equilibrium of netrin-1 in solution is abolished in the presence of heparin oligosaccharides and replaced with highly hierarchical and distinct super assemblies leading to unique, yet unknown netrin-1 filament formation. In our integrated approach we provide a molecular mechanism for the filament assembly which opens fresh paths towards a molecular understanding of netrin-1 functions.	Mar 2023
B23-Circular Dichroism	Mueller matrix polarimetry on cyanine dye J-aggregates Samuel R. Clowes , Dora M. Răsădean , Tiberiu-M. Gianga , Tamas Javorfi , Rohanah Hussain , Giuliano Siligardi , G. Dan Pantos Molecules 28 DOI: 10.3390/molecules28041523 Diamond Proposal Number(s): [29075, 31797] Open Access Show Abstract ▼ Abstract: Cyanine dyes are known to form H- and J-aggregates in aqueous solutions. Here we show that the cyanine dye, S0271, assembles in water into vortex induced chiral J-aggregates. The chirality of the J-aggregates depends on the directionality of the vortex. This study utilised both conventional benchtop CD spectropolarimeters and Mueller matrix polarimetry. It was found that J-aggregates have real chirality alongside linear dichroism and linear and circular birefringence. We identify the factors that are key to the formation of metastable chiral J-aggregates and propose a mechanism for their assembly.	Feb 2023
I21-Resonant Inelastic X-ray Scattering (RIXS)	Resonant inelastic x-ray scattering from U3O8 and UN Eleanor Lawrence Bright , Lei Xu , Lottie Harding , Ross Springell , Andrew Walters , Martin Sundermann , Mirian Garcia-Fernandez , Stefano Agrestini , Roberto Caciuffo , Gerrit Van Der Laan , Gerry H. Lander Journal Of Physics: Condensed Matter DOI: 10.1088/1361-648X/acb8f4 Diamond Proposal Number(s): [29274] Show Abstract ▼ Abstract: Resonant inelastic x-ray scattering (RIXS) using an incident energy tuned to the uranium N4,5 absorption edges is reported from epitaxial films of α-U3O8 and UN. Theory shows that for U3O8 the multiplets associated with a 5f1 configuration with a ground state of 2F5/2 and the excited state of 2F7/2 are observed. However, the strong transition predicted at a transfer energy of 1.67 eV is not observed. We assume this is a consequence of the intermediate state lifetime broadening due to interaction with continuum states when the transferred energy exceeds the onset of the continuum in the presence of the core hole. This hypothesis is supported by the results obtained for the 5f-itinerant system UN, where no sharp transitions have been observed, although the broad scattering response centered at ∼ 1 eV is considered a signature of a predominantly 5f3 configuration in this band-like semi-metallic system. These experiments and theory add important information on these materials, both of which have been investigated since the 1960s, as well as whether RIXS at the uranium N edge can become a valuable tool for actinide research.	Feb 2023
B16-Test Beamline	Determining the critical fracture stress of Al dendrites near the melting point via synchrotron X-ray imaging Ling Qin , Zhiguo Zhang , Baisong Guo , Wei Li , Jiawei Mi Acta Metallurgica Sinica (english Letters) 121 DOI: 10.1007/s40195-023-01531-w Diamond Proposal Number(s): [7440] Show Abstract ▼ Abstract: Dendrites are the most common microstructural features in the cast metals, significantly affecting the structure integrity and mechanical properties of the castings. In this study, the in situ synchrotron X-ray radiographic and tomographic imaging techniques were combined to evaluate the critical fracture stress of the growing dendrite tip during the solidification of an Al-15 wt% Cu alloy under an external electromagnetic force. Two dendritic 3D models have been proposed to simulate the dendrite 3D morphologic characteristics and thus revealed that the critical fracture stresses of the Al dendrites at temperatures close to its melting point were in the range of 0.5 kPa–0.05 MPa. The present results demonstrate the feasibility of measuring the high-temperature mechanical properties of the metallic dendrites.	Feb 2023
I04-Macromolecular Crystallography	An unusual disulfide-linked dimerization in the fluorescent protein rsCherryRev1.4 Thi Yen Hang Bui , Peter Dedecker , Luc Van Meervelt Acta Crystallographica Section F Structural Biology Communications 79, 38 - 44 DOI: 10.1107/S2053230X23000572 Diamond Proposal Number(s): [19190] Show Abstract ▼ Abstract: rsCherryRev1.4 has been reported as one of the reversibly photoswitchable variants of mCherry, and is an improved version with a faster off-switching speed and lower switching fatigue at high light intensities than its precursor rsCherryRev. However, rsCherryRev1.4 still has some limitations such as a tendency to dimerize as well as complex photophysical properties. Here, the crystal structure of rsCherryRev1.4 was determined at a resolution of 2 Å and it was discovered that it forms a dimer that shows disulfide bonding between the protomers. Mutagenesis, gel electrophoresis and size-exclusion chromatography strongly implicate Cys24 in this process. Replacing Cys24 in rsCherryRev1.4 resulted in a much lower tendency towards dimerization, while introducing Cys24 into mCherry correspondingly increased its dimerization. In principle, this finding opens the possibility of developing redox sensors based on controlled dimerization via disulfide cross-linking in fluorescent proteins, even though the actual application of engineering such sensors still requires additional research.	Feb 2023

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