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11,640 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I03-Macromolecular Crystallography	Development of a structural epitope mimic: an idiotypic approach to HCV vaccine design Vanessa M. Cowton , Ania M. Owsianka , Valeria Fadda , Ana Maria Ortega-prieto , Sarah J. Cole , Jane A. Potter , Jessica K. Skelton , Nathan Jeffrey , Caterina Di Lorenzo , Marcus Dorner , Garry L. Taylor , Arvind H. Patel Npj Vaccines 6 DOI: 10.1038/s41541-020-00269-1 Diamond Proposal Number(s): [10071] Open Access Show Abstract ▼ Abstract: HCV vaccine development is stymied by the high genetic diversity of the virus and the variability of the envelope glycoproteins. One strategy to overcome this is to identify conserved, functionally important regions—such as the epitopes of broadly neutralizing antibodies (bNAbs)—and use these as a basis for structure-based vaccine design. Here, we report an anti-idiotype approach that has generated an antibody that mimics a highly conserved neutralizing epitope on HCV E2. Crucially, a mutagenesis screen was used to identify the antibody, designated B2.1 A, whose binding characteristics to the bNAb AP33 closely resemble those of the original antigen. Protein crystallography confirmed that B2.1 A is a structural mimic of the AP33 epitope. When used as an immunogen B2.1 A induced antibodies that recognized the same epitope and E2 residues as AP33 and most importantly protected against HCV challenge in a mouse model.	Dec 2021
I13-2-Diamond Manchester Imaging	4D micro-scale, phase-contrast X-ray imaging and computed tomography of HMX-based polymer-bonded explosives during thermal runaway G. R. Parker , D. S. Eastwood , M. Storm , K. Vitharana , E. M. Heatwole , I. Lopez-pulliam , R. M. Broilo , P. M. Dickson , A. Martinez , Christoph Rau , N. K. Bourne Combustion And Flame 226, 478 - 489 DOI: 10.1016/j.combustflame.2020.12.025 Diamond Proposal Number(s): [15068, 16650, 18198] Show Abstract ▼ Abstract: High-resolution synchrotron x-ray radiography with computed tomography is used to observe the evolution of porosity created by thermal exposure in two HMX-based polymer-bonded explosive compositions; LX-04 and BX-63. The measurements were made in situ, over an extended period of time, during which the samples were heated on a slow-rate thermal trajectory. The tests ended with thermal-runaway to ignition after which the samples were consumed by combustion. The primary means of damage appears to be from mechanical debonding of the HMX-binder interface with secondary contribution from chemical decomposition. Confinement and binder properties affect the amount of porosity and permeability that develops. Additionally, observations were made describing the emergence and structure of an internal ignition volume, the formation and transport of a pre-ignition melt layer, and how the early stages of combustion were affected by material morphology, mechanical confinement and melt. The contact angle between molten HMX and the fluoropolymer, Viton A, is also presented. For the first time we have time-resolved x-ray images of ignition in sufficient detail to verify the mechanism of cookoff in polymer-bonded explosive compositions.	Apr 2021
I12-JEEP: Joint Engineering, Environmental and Processing	Growth dynamics of faceted Al13Fe4 intermetallic revealed by high-speed synchrotron X-ray quantification Zihan Song , Oxana V. Magdysyuk , Lei Tang , Tay Sparks , Biao Cai Journal Of Alloys And Compounds DOI: 10.1016/j.jallcom.2021.158604 Diamond Proposal Number(s): [19216] Show Abstract ▼ Abstract: High-speed synchrotron tomography was used to investigate the nucleation and growth dynamics of Al13Fe4 intermetallic during solidification of an Al-5wt%Fe alloy, providing new insights into its formation process. The majority of Al13Fe4 intermetallics nucleated near the surface oxide of the specimen and a few nucleated at Al13Fe4 phase. Al13Fe4 crystals grew into a variety of shapes, including plate-like, hexagonal tabular, stair-like and V-shaped, which can be attributed to the crystal structure of this compound and its susceptibility to twinning. Hole-like defects filled with aluminium melt were observed within the intermetallics. Oriented particle attachment mechanism was proposed to explain the formation of the Al13Fe4 intermetallic, which needs further experiments and simulation to confirm.	Apr 2021
I04-Macromolecular Crystallography I24-Microfocus Macromolecular Crystallography	Functionalization of the BCL6 BTB domain into a noncovalent crystallization chaperone Thomas Zacharchenko , Stephanie Wright Iucrj 8 DOI: 10.1107/S2052252520015754 Diamond Proposal Number(s): [15378, 19248] Open Access Show Abstract ▼ Abstract: The production of diffraction-quality protein crystals is challenging and often requires bespoke, time-consuming and expensive strategies. A system has been developed in which the BCL6 BTB domain acts as a crystallization chaperone and promiscuous assembly block that may form the basis for affinity-capture crystallography. The protein of interest is expressed with a C-terminal tag that interacts with the BTB domain, and co-crystallization leads to its incorporation within a BTB-domain lattice. This strategy was used to solve the structure of the SH3 domain of human nebulin, a structure previously solved by NMR, at 1.56 Å resolution. This approach is simple and effective, requiring only routine protein complexation and crystallization screening, and should be applicable to a range of proteins.	Mar 2021
B18-Core EXAFS I20-Scanning-X-ray spectroscopy (XAS/XES)	Manganese containing copper aluminate catalysts: Genesis of structures and active sites for hydrogenation of aldehydes Christoph Dörfelt , Michelle Hammerton , David Martin , Alexander Wellmann , Clara C. Aletsee , Moniek Tromp , Klaus Köhler Journal Of Catalysis 395, 80 - 90 DOI: 10.1016/j.jcat.2020.12.017 Diamond Proposal Number(s): [16558] Show Abstract ▼ Abstract: Copper aluminate spinel (CuO.CuAl2O4) is the favoured Cr-free substitute for the copper chromite catalyst (CuO.CuCr2O4) in the industrial hydrogenation of aldehydes. New insights in the catalytic mechanism were obtained by systematically studying the structure and activity of these catalysts including effects of manganese as a catalyst component. The hydrogenation of butyraldehyde to butanol was studied as a model reaction and the active structure was characterised using X-ray diffraction, temperature programmed reduction, N2O chemisorption, EXAFS and XANES, including in-situ investigations. The active catalyst is a reduced spinel lattice that is stabilised by protons, with copper metal nanoparticles grown upon its surface. Incorporation of Mn into the spinel lattice has a profound effect on the spinel structure. Mn stabilises the spinel towards reduction of CuII to Cu0 by occupation of tetrahedral sites with Mn cations, but also causes decreased catalytic activity. Structural data, combined with the effect on catalysis, indicate a predominantly interface-based reaction mechanism, involving both the spinel and copper nanoparticle surface in protonation and reduction of the aldehyde. The electron reservoir of the metallic copper particles is regenerated by the dissociative adsorption and oxidation of H2 on the metal surface. The generated protons are stored in the spinel phase, acting as proton reservoir. Cu(I) species located within the spinel and identified by XANES are probably not involved in the catalytic cycle.	Mar 2021
B21-High Throughput SAXS I04-1-Macromolecular Crystallography (fixed wavelength)	Discriminative SKP2 interactions with CDK-cyclin complexes support a cyclin a-specific role in p27KIP1 degradation Marco Salamina , Bailey C. Montefiore , Mengxi Liu , Daniel J. Wood , Richard Heath , James R. Ault , Lan-zhen Wang , Svitlana Korolchuk , Arnaud Basle , Martyna Pastok , Judith Reeks , Natalie J. Tatum , Frank Sobott , Stefan T. Arold , Michele Pagano , Martin E. M. Noble , Jane A. Endicott Journal Of Molecular Biology 433 DOI: 10.1016/j.jmb.2020.166795 Diamond Proposal Number(s): [13587, 16970] Open Access Show Abstract ▼ Abstract: The SCFSKP2 ubiquitin ligase relieves G1 checkpoint control of CDK-cyclin complexes by promoting p27KIP1 degradation. We describe reconstitution of stable complexes containing SKP1-SKP2 and CDK1-cyclin B or CDK2-cyclin A/E, mediated by the CDK regulatory subunit CKS1. We further show that a direct interaction between a SKP2 N-terminal motif and cyclin A can stabilize SKP1-SKP2-CDK2-cyclin A complexes in the absence of CKS1. We identify the SKP2 binding site on cyclin A and demonstrate the site is not present in cyclin B or cyclin E. This site is distinct from but overlapping with features that mediate binding of p27KIP1 and other G1 cyclin regulators to cyclin A. We propose that the capacity of SKP2 to engage with CDK2-cyclin A by more than one structural mechanism provides a way to fine tune the degradation of p27KIP1 and distinguishes cyclin A from other G1 cyclins to ensure orderly cell cycle progression.	Mar 2021
I18-Microfocus Spectroscopy	Co-application of Se and a biostimulant at different wheat growth stages: Influence on grain development Tingting Xiao , Roberto Boada , Mercè Llugany , Manuel Valiente Plant Physiology And Biochemistry 160, 184 - 192 DOI: 10.1016/j.plaphy.2021.01.025 Diamond Proposal Number(s): [18671] Show Abstract ▼ Abstract: An appropriate selenium intake can be beneficial for human health. Se-biofortified food in Se-deficient regions is becoming an increasingly common practice but there are still issues to be addressed regarding the observed Se-induced toxicity to the plant. In this respect, plant biostimulants are used to enhance nutrition efficiency, abiotic stress tolerance and crop quality. In this work, the efficacy of a plant biostimulant to counteract the Se-induced stress in wheat plants is experimentally assessed. The co-application of different Se-biofortification treatments and the biostimulant at different growth stages (tillering or heading stage) was investigated. The use of micro focused X-ray spectroscopy allows us to confirm organic Se species to be the main Se species found in wheat grain and that the proportion of organic Se species is only slightly affected by the Se application stage. Our study proves that the biostimulant had a key role in the enhancement of both the amount of grains produced per spike and their dry biomass without hindering Se enrichment process, neither diminishing the Se concentration nor massively disrupting the Se species present. This information will be useful to minimize both plant toxicity and economic cost towards a more effective and plant healthy selenium supplementation.	Mar 2021
I12-JEEP: Joint Engineering, Environmental and Processing	Investigating the microstructure and mechanical behaviour of simulant “lava-like” fuel containing materials from the Chernobyl reactor unit 4 meltdown C. Paraskevoulakos , J. P. Forna-kreutzer , K. R. Hallam , C. P. Jones , T. B. Scott , C. Gausse , D. J. Bailey , C. A. Simpson , D. Liu , C. Reinhard , C. L. Corkhill , M. Mostafavi Materials & Design 201 DOI: 10.1016/j.matdes.2021.109502 Diamond Proposal Number(s): [20189] Open Access Show Abstract ▼ Abstract: Decommissioning of the damaged Chernobyl nuclear reactor Unit 4 is a top priority for the global community. Before such operations begin, it is crucial to understand the behaviour of the hazardous materials formed during the accident. Since those materials formed under extreme and mostly unquantified conditions, modelling alone is insufficient to accurately predict their physical, chemical and, predominantly, mechanical behaviour. Meanwhile, knowledge of the mechanical characteristics of those materials, such as their strength, is a priority before robotic systems are employed for retrieval and the force expected from them to be exerted is one of the key design questions. In this paper we target to measurement of the standard mechanical properties of the materials formed during the accident by testing small-scale, low radioactivity simulants. A combined methodology using Hertzian indentation, synchrotron X-ray tomography and digital volume correlation (DVC), was adopted to estimate the mechanical properties. Displacement fields around the Hertzian indentation, performed in-situ in a synchrotron, were measured by analysing tomograms with DVC. The load applied during the indentation, combined with full-field displacement measured by DVC was used to estimate the mechanical properties, such as Young's modulus and Poisson's ratio of these hazardous materials.	Mar 2021
E02-JEM ARM 300CF	Contrast transfer and noise considerations in focused-probe electron ptychography Colum M. O'leary , Gerardo T. Martinez , Emanuela Liberti , Martin J. Humphry , Angus I. Kirkland , Peter D. Nellist Ultramicroscopy 221 DOI: 10.1016/j.ultramic.2020.113189 Diamond Proposal Number(s): [20431, 22317] Show Abstract ▼ Abstract: Electron ptychography is a 4-D STEM phase-contrast imaging technique with applications to light-element and beam-sensitive materials. Although the electron dose (electrons incident per unit area on the sample) is the primary figure of merit for imaging beam-sensitive materials, it is also necessary to consider the contrast transfer properties of the imaging technique. Here, we explore the contrast transfer properties of electron ptychography. The contrast transfer of focused-probe, non-iterative electron ptychography using the single-side-band (SSB) method is demonstrated experimentally. The band-pass nature of the phase-contrast transfer function (PCTF) for SSB ptychography places strict limitations on the probe convergence semi-angles required to resolve specific sample features with high contrast. The PCTF of the extended ptychographic iterative engine (ePIE) is broader than that for SSB ptychography, although when both high and low spatial frequencies are transferred, band-pass filtering is required to remove image artefacts. Normalisation of the transfer function with respect to the noise level shows that the transfer window is increased while avoiding noise amplification. Avoiding algorithms containing deconvolution steps may also increase the dose-efficiency of ptychographic phase reconstructions.	Feb 2021
I02-Macromolecular Crystallography	Structure-guided design of a synthetic mimic of an endothelial protein c receptor-binding PfEMP1 protein Natalie M. Barber , Clinton K. Y. Lau , Louise Turner , Gareth Watson , Susan Thrane , John P. A. Lusingu , Thomas Lavstsen , Matthew K. Higgins Msphere 6 DOI: 10.1128/mSphere.01081-20 Open Access Show Abstract ▼ Abstract: Structure-guided vaccine design provides a route to elicit a focused immune response against the most functionally important regions of a pathogen surface. This can be achieved by identifying epitopes for neutralizing antibodies through structural methods and recapitulating these epitopes by grafting their core structural features onto smaller scaffolds. In this study, we conducted a modified version of this protocol. We focused on the PfEMP1 protein family found on the surfaces of erythrocytes infected with Plasmodium falciparum. A subset of PfEMP1 proteins bind to endothelial protein C receptor (EPCR), and their expression correlates with development of the symptoms of severe malaria. Structural studies revealed that PfEMP1 molecules present a helix-kinked-helix motif that forms the core of the EPCR-binding site. Using Rosetta-based design, we successfully grafted this motif onto a three-helical bundle scaffold. We show that this synthetic binder interacts with EPCR with nanomolar affinity and adopts the expected structure. We also assessed its ability to bind to antibodies found in immunized animals and in humans from malaria-endemic regions. Finally, we tested the capacity of the synthetic binder to effectively elicit antibodies that prevent EPCR binding and analyzed the degree of cross-reactivity of these antibodies across a diverse repertoire of EPCR-binding PfEMP1 proteins. Despite our synthetic binder adopting the correct structure, we find that it is not as effective as the CIDRα domain on which it is based for inducing adhesion-inhibitory antibodies. This cautions against the rational design of focused immunogens that contain the core features of a ligand-binding site of a protein family, rather than those of a neutralizing antibody epitope.	Feb 2021

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