I09-Surface and Interface Structural Analysis
|
B. F.
Spencer
,
S.
Maniyarasu
,
B.
Reed
,
D. J. H.
Cant
,
R.
Ahumada-lazo
,
A. G.
Thomas
,
C. A.
Muryn
,
M.
Maschek
,
S. K.
Eriksson
,
T.
Wiell
,
T.-l.
Lee
,
S.
Tougaard
,
A. G.
Shard
,
W. R.
Flavell
Diamond Proposal Number(s):
[20059]
Abstract: Hard X-ray Photoelectron Spectroscopy (HAXPES) provides minimally destructive depth profiling into the bulk, extending the photoelectron sampling depth. Detection of deeply buried layers beyond the elastic limit is enabled through inelastic background analysis. To test the robustness of this technique, we present results on a thin (18 nm) layer of buried metal-organic complex buried below up to 200 nm of organic material. Overlayers with thicknesses 25-140 nm were measured using photon energies ranging 6-10 keV at the I09 end station at Diamond Light Source, and a new fixed energy Ga Kα (9.25 keV) laboratory-based HAXPES spectrometer was also used to measure samples with overlayers up to 200 nm thick. The sampling depth was varied: at Diamond Light Source by changing the photon energy, and in the lab system by performing angle-resolved measurements. For all the different overlayers and sampling depths, inelastic background modelling consistently provided thicknesses which agreed, within reasonable error, with the ellipsometric thickness. Relative sensitivity factors were calculated, and these factors consistently provided reasonable agreement with the expected nominal stoichiometry, suggesting the calculation method can be extended to any element. These results demonstrate the potential for the characterisation of deeply buried layers using synchrotron and laboratory-based HAXPES.
|
Dec 2020
|
|
B16-Test Beamline
|
M.
Borri
,
C.
Cohen
,
O.
Fox
,
J.
Groves
,
W.
Helsby
,
O.
Mathon
,
L.
Mcnicholl
,
S.
Pascarelli
,
K.
Sawhney
,
R.
Torchio
,
M.
Zuvic
Diamond Proposal Number(s):
[24637]
Open Access
Abstract: Germanium micro-strip sensors were selected as the sensor technology to take data in energy dispersive X-ray spectroscopy experiments at the Extremely Brilliant Source (EBS) in Grenoble (FR). It is important for this experimental technique to use sensors with a large uniform area and a fine pitch. The former determines the range of energy detectable with a single sensor. The latter improves spectral resolution. A high stopping power is also important to perform studies with hard X-rays.
The device under test in this measurement was a germanium micro-strip sensor made of 1024 strips with
pitch. The bulk was 1.5 mm thick. The sensor was assembled into a prototype cryostat part of the XH detector system. The device was tested at the B16 beamline at the Diamond Light Source (DLS) in Didcot (UK). The objective of the test-beam was to characterise charge-sharing between strips. In fact, this effect limits the spectral resolution of the device.
To carry out this test, the sensor was scanned over a subset of strips with micro-focused X-rays under different settings. These were beam energy and intensity, sensor temperature and bias voltage. Results are presented in this paper. It was measured that the full width half maximum of the charge-sharing profile across different strips was
for settings which were indicative of the experimental conditions at the EBS. This was a signal current per unit area on the sensor of
10−8 A/
, a bias voltage of -180 V and a temperature of -159
C.
|
Dec 2020
|
|
B21-High Throughput SAXS
|
Open Access
Abstract: The design of a multipurpose sample cell holder for the high-throughput (HT) beamline B21 is presented. The device is compatible with the robot bioSAXS sample changer currently installed on BM29, ESRF, and P12 Petra IV synchrotrons. This work presents an approach that uses 3D-printing to make hardware alterations which can expand the versatility of HT beamlines at low cost.
|
Dec 2020
|
|
I16-Materials and Magnetism
|
Stephan
Geprags
,
Bjorn Erik
Skovdal
,
Monika
Scheufele
,
Matthias
Opel
,
Didier
Wermeille
,
Paul
Thompson
,
Alessandro
Bombardi
,
Virginie
Simonet
,
Stephane
Grenier
,
Pascal
Lejay
,
Gilbert Andre
Chahine
,
Diana Lucia
Quintero-castro
,
Rudolf
Gross
,
Danny
Mannix
Diamond Proposal Number(s):
[12770]
Abstract: We report on a comprehensive investigation of the effects of strain and film thickness on the structural and magnetic properties of epitaxial thin films of the prototypal
J
eff
=
1
/
2
compound
Sr
2
IrO
4
by advanced x-ray scattering. We find that the
Sr
2
IrO
4
thin films can be grown fully strained up to a thickness of 108 nm. By using x-ray resonant scattering, we show that the out-of-plane magnetic correlation length is strongly dependent on the thin film thickness, but independent of the strain state of the thin films. This can be used as a finely tuned dial to adjust the out-of-plane magnetic correlation length and transform the magnetic anisotropy from two-dimensional to three-dimensional behavior by incrementing film thickness. These results provide a clearer picture for the systematic control of the magnetic degrees of freedom in epitaxial thin films of
Sr
2
IrO
4
and bring to light the potential for a rich playground to explore the physics of
5
d
transition-metal compounds.
|
Dec 2020
|
|
I03-Macromolecular Crystallography
|
Diamond Proposal Number(s):
[26302, 24732]
Abstract: The peroxisomal multifunctional enzyme type 1 (MFE1) catalyzes two successive reactions in the β-oxidation cycle: the 2E-enoyl-CoA hydratase (ECH) and NAD+-dependent 3S-hydroxyacyl-CoA dehydrogenase (HAD) reactions. MFE1 is a monomeric enzyme that has five domains. The N-terminal part (domains A and B) adopts the crotonase fold and the C-terminal part (domains C, D and E) adopts the HAD fold. A new crystal form of MFE1 has captured a conformation in which both active sites are noncompetent. This structure, at 1.7 Å resolution, shows the importance of the interactions between Phe272 in domain B (the linker helix; helix H10 of the crotonase fold) and the beginning of loop 2 (of the crotonase fold) in stabilizing the competent ECH active-site geometry. In addition, protein crystallographic binding studies using optimized crystal-treatment protocols have captured a structure with both the 3-ketodecanoyl-CoA product and NAD+ bound in the HAD active site, showing the interactions between 3-ketodecanoyl-CoA and residues of the C, D and E domains. Structural comparisons show the importance of domain movements, in particular of the C domain with respect to the D/E domains and of the A domain with respect to the HAD part. These comparisons suggest that the N-terminal part of the linker helix, which interacts tightly with domains A and E, functions as a hinge region for movement of the A domain with respect to the HAD part.
|
Dec 2020
|
|
I04-Macromolecular Crystallography
|
David T.
Davies
,
Simon
Leiris
,
Magdalena
Zalacain
,
Nicolas
Sprynski
,
Jérôme
Castandet
,
Justine
Bousquet
,
Clarisse
Lozano
,
Agustina
Llanos
,
Laethitia
Alibaud
,
Srinivas
Vasa
,
Ramesh
Pattipati
,
Ravindar
Valige
,
Bhaskar
Kummari
,
Srinivasu
Pothukanuri
,
Cyntia
De Piano
,
Ian
Morrissey
,
Kirsty
Holden
,
Peter
Warn
,
Francesca
Marcoccia
,
Manuela
Benvenuti
,
Cecilia
Pozzi
,
Giusy
Tassone
,
Stefano
Mangani
,
Jean-denis
Docquier
,
David
Pallin
,
Richard
Elliot
,
Marc
Lemonnier
,
Martin
Everett
Diamond Proposal Number(s):
[21741]
Abstract: The diazabicyclooctanes (DBOs) are a class of serine β-lactamase (SBL) inhibitors that use a strained urea moiety as the warhead to react with the active serine residue in the active site of SBLs. The first in-class drug, avibactam, as well as several other recently approved DBOs (e.g., relebactam) or those in clinical development (e.g., nacubactam and zidebactam) potentiate activity of β-lactam antibiotics, to various extents, against carbapenem-resistant Enterobacterales (CRE) carrying class A, C, and D SBLs; however, none of these are able to rescue the activity of β-lactam antibiotics against carbapenem-resistant Acinetobacter baumannii (CRAB), a WHO “critical priority pathogen” producing class D OXA-type SBLs. Herein, we describe the chemical optimization and resulting structure–activity relationship, leading to the discovery of a novel DBO, ANT3310, which uniquely has a fluorine atom replacing the carboxamide and stands apart from the current DBOs in restoring carbapenem activity against OXA-CRAB as well as SBL-carrying CRE pathogens.
|
Dec 2020
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
W. U.
Mirihanage
,
J. D.
Robson
,
S.
Mishra
,
P.
Hidalgo-manrique
,
J.
Quinta Da Fonseca
,
C. S.
Daniel
,
P. B.
Prangnell
,
S.
Michalik
,
O. V.
Magdysyuk
,
T.
Connolley
,
M.
Drakopoulos
Diamond Proposal Number(s):
[13828]
Open Access
Abstract: An improved understanding of the phenomenon of dynamic precipitation is important to accurately model and simulate many industrial manufacturing processes with high strength Al-alloys. Dynamic ageing in 7xxx Al-alloys can occur as a result of both the strain and heat. Small angle X-ray scattering (SAXS) is an advanced technique that allows the precipitation processes to be studied in situ, but to date this has only been possible at lower than industrially relevant strain rates (e.g. < 10−3). In this contribution, we demonstrate the potential of in-situ SAXS studies of metallic alloys at higher strain rates (10−2) than previously, using a high energy synchrotron X-ray. The time resolved SAXS information has been used to evaluate dynamic precipitate evolution models and has demonstrated that at high strain rates a new regime must be considered which includes the more significant effect of vacancy annihilation, leading to a clear strain rate, rather than just strain, kinetic dependence.
|
Dec 2020
|
|
I03-Macromolecular Crystallography
|
Diamond Proposal Number(s):
[17773]
Open Access
Abstract: Tripartite α-pore-forming toxins are constructed of three proteins (A, B and C) and are found in many bacterial pathogens. While structures of the B and C components from Gram-negative bacteria have been described, the structure of the A component of a Gram-negative α-pore-forming toxin has so far proved elusive. SmhA, the A component from the opportunistic human pathogen Serratia marcescens, has been cloned, overexpressed and purified. Crystals were grown of selenomethionine-derivatized protein and anomalous data were collected. Phases were calculated and an initial electron-density map was produced.
|
Dec 2020
|
|
I20-Scanning-X-ray spectroscopy (XAS/XES)
|
Open Access
Abstract: The heterogeneously catalyzed oxidation of bioethanol offers a promising route to bio-based acetic acid. Here, we assess an alternative method to support gold nanoparticles, which aims to improve selectivity to acetic acid through minimizing over-oxidation to carbon dioxide. The most promising support system is 5 wt % titanium on silica, which combines the high surface area of silica with the stabilizing effect of titania on the gold particles. Compared to gold–silica systems, which require a complex synthesis method, small quantities of titanium promoted the formation of gold nanoparticles during a simple deposition–precipitation. Characterization of the catalyst with X-ray absorption spectroscopy shows that titanium is highly dispersed in the form of small, possibly dimeric, titanium(IV) structures, which are isolated and stabilize gold nanoparticles, possibly minimizing sintering effects during synthesis. The size of the gold particles depends on the pre-treatment of the titanium–silica support before gold deposition, with larger titanium structures hosting larger gold particles. Acetic acid yield over the titanium–silica-supported gold systems improved by about 1.6 times, compared to pure titania-supported gold. The high activity of those catalysts suggests that bulk, crystalline titania is not required for the reaction, encouraging the use of mixed supports to combine their benefits. Those support systems, besides improving selectivity, offer high surface area and a low-cost filler material, which brings ethanol oxidation one step further to the industry. Additionally, the low loading of titanium permits studying the reaction mechanisms on the gold–titanium interface with bulk characterization techniques.
|
Dec 2020
|
|
I03-Macromolecular Crystallography
I04-Macromolecular Crystallography
|
Gavin W.
Collie
,
Iacovos N.
Michaelides
,
Kevin
Embrey
,
Christopher J.
Stubbs
,
Ulf
Börjesson
,
Ian L.
Dale
,
Arjan
Snijder
,
Louise
Barlind
,
Kun
Song
,
Puneet
Khurana
,
Christopher
Phillips
,
R. Ian
Storer
Open Access
Abstract: We report here a fragment screen directed toward the c-MET kinase from which we discovered a series of inhibitors able to bind to a rare conformation of the protein in which the P-loop adopts a collapsed, or folded, arrangement. Preliminary SAR exploration led to an inhibitor (7) with nanomolar biochemical activity against c-MET and promising cell activity and kinase selectivity. These findings increase our structural understanding of the folded P-loop conformation of c-MET and provide a sound structural and chemical basis for further investigation of this underexplored yet potentially therapeutically exploitable conformational state.
|
Dec 2020
|
|
