Diamond Light Source (United Kingdom)

Abstract: This paper provides an overview of the discussion and presentations from the Workshop on the Management of Large CryoEM Facilities held at the New York Structural Biology Center, New York, NY on February 6-7, 2017. A major objective of the workshop was to discuss best practices for managing cryoEM facilities. The discussions were largely focused on supporting single-particle methods for cryoEM and topics included: user access, assessing projects, workflow, sample handling, microscopy, data management and processing, and user training.

Abstract: SrMnSb22 is suggested to be a magnetic topological semimetal. It contains square, 2D Sb planes with non-symmorphic crystal symmetries that could protect band crossings, offering the possibility of a quasi-2D, robust Dirac semi-metal in the form of a stable, bulk (3D) crystal. Here, we report a combined and comprehensive experimental and theoretical investigation of the electronic structure of SrMnSb22, including the first ARPES data on this compound. SrMnSb22 possesses a small Fermi surface originating from highly 2D, sharp and linearly dispersing bands (the Y-states) around the (0,π/a)-point in k-space. The ARPES Fermi surface agrees perfectly with that from bulk-sensitive Shubnikov de Haas data from the same crystals, proving the Y−states to be responsible for electrical conductivity in SrMnSb22. DFT and tight binding (TB) methods are used to model the electronic states, and both show good agreement with the ARPES data. Despite the great promise of the latter, both theory approaches show the Y-states to be gapped above EF, suggesting trivial topology. Subsequent analysis within both theory approaches shows the Berry phase to be zero, indicating the non-topological character of the transport in SrMnSb22, a conclusion backed up by the analysis of the quantum oscillation data from our crystals.

Abstract: The next generation of X-ray telescopes will require both high resolution and high sensitivity to target the earliest astronomical objects, to this end the UK based Smart X-ray Optics (SXO) project has been investigating the application of active/adaptive optics to traditional grazing incidence X-ray optics and this has resulted in the fabrication and testing of our first active X-ray prototype in November 2008. Results from these initial tests have proved very encouraging for this advancing technology and have highlighted the prototype's ability to deform its optical surface through piezoelectric actuation. We present a critical analysis of the first prototype system, discussing metrology of the mandrel, the nickel replicated ellipsoidal optics and the prototype. The measured actuator influence functions of the prototype are compared against finite element analysis simulations and the observed characteristics are then described. The advances required in the current technology are then outlined in relation to a second generation of active X-ray prototype, which is scheduled for X-ray testing in 2010.

Abstract: This study focuses on microstructural changes that occur within the mammalian lung when subject to blast and how these changes influence strain distributions within the tissue. Shock tube experiments were performed to generate the blast injured specimens (cadaveric Sprague-Dawley rats). Blast overpressures of 100 kPa and 180 kPa were studied. Synchrotron tomography imaging was used to capture volumetric image data of lungs. Specimens were ventilated using a custom-built system to study multiple inflation pressures during each tomography scan. This data enabled the first digital volume correlation (DVC) measurements in lung tissue to be performed. Quantitative analysis was performed to describe the damaged architecture of the lung. No clear changes in the microstructure of the tissue morphology were observed due to controlled low to moderate level blast exposure. However, significant focal sites of injury were observed using DVC, which allowed detection of bias and concentration in the patterns of strain level. Morphological analysis corroborated the findings, illustrating that the focal damage caused by a blast can give rise to diffuse influence across the tissue. It is important to characterise the non-instantly fatal doses of blast, given the transient nature of blast lung in the clinical setting. This research has highlighted the need for better understanding of focal injury and its zone of influence (alveolar inter-dependency and neighbouring tissue burden as a result of focal injury). Digital volume correlation techniques show great promise as a tool to advance this endeavour, providing a new perspective on lung mechanics post-blast.

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.