I18-Microfocus Spectroscopy
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Thomas
Barthelay
,
Robert
Gray
,
Howard
Richards
,
Paloma
Rodriguez Santana
,
Sylvia
Britto
,
Kalotina
Geraki
,
Zhenyuan
Xia
,
Johanna
Xu
,
Leif E.
Asp
,
Chris
Bowen
,
Frank
Marken
,
Alexander
Lunt
,
Andrew
Rhead
Diamond Proposal Number(s):
[30127]
Open Access
Abstract: Structural batteries utilise the bifunctionality of carbon fibres to act as a load-bearing structure, but also as a conductive current collector for a battery electrode. Lithium-ion transport during the cycling of structural battery cathodes coated with different morphologies is investigated using Iron X-Ray Absorption Near Edge Spectroscopy (Fe XANES) and correlated to electrochemical performance. Two contrasting morphologies were produced using slurry coating and electrophoretic deposition (EPD) of lithium-iron phosphate (LFP) onto continuous carbon fibres. The ability to study the different structural battery cathode morphologies operando allows for a comparative analysis of their impact on cycling performance. The EPD-coated fibres exhibited a more homogeneous, thinner coating around the fibre compared to the thick, one-sided coating produced using slurry coating. Despite a lower initial capacity and 30 % lithium re-intercalation loss in the first cycle, EPD-coated fibres exhibited more stable capacity retention over time compared to slurry-coated counterparts. Electrochemical Impedance Spectroscopy (EIS) revealed initially high ionic resistance for the EPD-coated fibres, but a larger increase in resistance in the slurry coated electrodes over multiple cycles. This study demonstrated an innovative and novel method of analysing in greater detail, the cycling ability of the coated cathode material on carbon fibres using synchrotron radiation.
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Feb 2025
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I10-Beamline for Advanced Dichroism - scattering
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Abstract: Depth resolved characterization of structural and magnetic profiles of antiferromagnetic/ferromagnetic (AFM/FM) system upon annealing was performed in this work. We studied systems comprising of AFM IrMn
and FM (Co, Fe, Co70Fe30) bilayer structures using magnetometry, polarized neutron reflectometry, soft X-ray magnetic circular dichroism and secondary neutral spectrometry. Structural depth profiles obtained from neutron reflectometry indicate non-homogeneity of the AFM layer even before annealing, which is associated with the migration of manganese to the surface of the sample. Annealing of samples with CoFe and Co layers leads to a slight increase (
5 %) in the migration of manganese, which, however, does not lead to significant degradation of the exchange coupling at the AFM/FM interface. A significantly different picture was observed in the Fe/IrMn
systems where a strong migration of iron into the AFM layer was observed upon annealing of the sample, leading to erosion of the magnetic profile, the formation of a non-magnetic alloy and degradation of the pinning strength. This study can be useful in the optimization of AFM/FM systems in different spintronics devices, including HDD read heads, where thermal annealing is applied at different stages of the device manufacturing process.
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Jan 2025
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I03-Macromolecular Crystallography
I04-1-Macromolecular Crystallography (fixed wavelength)
I04-Macromolecular Crystallography
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Diamond Proposal Number(s):
[17212, 23269]
Open Access
Abstract: Angiotensin-1-converting enzyme (ACE) is a zinc-dependent carboxypeptidase of therapeutic interest for the treatment of hypertension, inflammation and fibrosis. It consists of two homologous N and C catalytic domains, nACE and cACE, respectively. Unfortunately, the current clinically available ACE inhibitors produce undesirable side effects due to the nonselective inhibition of these domains. Through structure-based drug design, we previously identified a series of diprolyl-derived inhibitors (SG3, SG15, SG16, SG17 and SG18) in an attempt to specifically target nACE. Only one compound, SG16, possessed significant nACEselectivity. The previously determined 16-nACE crystal structure (nACE:SG16) suggested interactions with Tyr369 (Phe381 in cACE) are responsible for this selectivity. To better understand the molecular basis for the lack of selectivity in the remaining compounds, we have cocrystallised nACE in complex with SG3, SG15, SG17 and SG18 and cACE in complex with SG3, SG15, SG16 and SG18 and determined their structures at high resolution. Apart from the catalytic residues, these structures further highlight the importance of residues distal to the active site that may play an important role in the design of domain-selective inhibitors of ACE.
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Jan 2025
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I04-Macromolecular Crystallography
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Open Access
Abstract: The mutually antagonistic relationship of atypical protein kinase C (aPKC) and partitioning-defective protein 6 (Par6) with the substrate lethal (2) giant larvae (Lgl) is essential for regulating polarity across many cell types. Although aPKC–Par6 phosphorylates Lgl at three serine sites to exclude it from the apical domain, aPKC–Par6 and Lgl paradoxically form a stable kinase–substrate complex, with conflicting roles proposed for Par6. We report the structure of human aPKCι–Par6α bound to full-length Llgl1, captured through an aPKCι docking site and a Par6PDZ contact. This complex traps a phospho-S663 Llgl1 intermediate bridging between aPKC and Par6, impeding phosphorylation progression. Thus, aPKCι is effectively inhibited by Llgl1pS663 while Llgl1 is captured by aPKCι–Par6. Mutational disruption of the Lgl–aPKC interaction impedes complex assembly and Lgl phosphorylation, whereas disrupting the Lgl–Par6PDZ contact promotes complex dissociation and Lgl phosphorylation. We demonstrate a Par6PDZ-regulated substrate capture-and-release model requiring binding by active Cdc42 and the apical partner Crumbs to drive complex disassembly. Our results suggest a mechanism for mutual regulation and spatial control of aPKC–Par6 and Lgl activities.
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Jan 2025
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I07-Surface & interface diffraction
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Diamond Proposal Number(s):
[32266]
Abstract: Organic solar cells (OSCs) are attracting significant attention due to their low cost, lightweight, and flexible nature. The introduction of nonfullerene acceptors (NFAs) has propelled OSC development into a transformative era. However, the limited availability of wide band gap polymer donors for NFAs poses a critical challenge, hindering further advancements. This study examines the role of developed wide band gap halogenated pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (PPD)-based polymers, in combination with the Y6 nonfullerene acceptor, in bulk heterojunction (BHJ) OSCs. We first focus on the electronic and absorbance modifications brought about by halogen substitution in PPD-based polymers, revealing how these adjustments influence the HOMO/LUMO energy levels and, subsequently, photovoltaic performance. Despite the increased Voc of halogenated polymers due to the optimal band alignment, power conversion efficiencies (PCEs) were decreased due to suboptimal blend morphologies. We second implemented PPD as a solid additive to PM6:Y6, forming ternary OSCs and further improving the PCE. The study provides a nuanced understanding of the interplay between molecular design, device morphology, and OSC performance and opens insights for future research to achieve an optimal balance between band alignment and favorable blend morphology for high-efficiency OSCs.
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Jan 2025
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I11-High Resolution Powder Diffraction
I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[30461, 31578]
Abstract: Batteries are a critical technology for the transition to a sustainable energy economy. Rechargeable lithium ion (Li ion) batteries power our electronic devices and electric cars and are needed to store energy generated from renewable sources. The design and discovery of new materials underpins the development of high performing and reliable rechargeable batteries that are long-lasting, cost-effective, fast charging, safe and sustainable. Most Li-ion batteries rely on a liquid electrolyte to conduct ions between the anode and cathode. However, liquid electrolytes can leak and are flammable, which can lead to fires. One solution to this issue is to use a solid electrolyte, and researchers at the University of Liverpool have discovered a solid material with high enough Li ion conductivity to replace the liquid electrolytes in current Li ion battery technology, improving safety and energy capacity. Their work, recently published in Science, used a collaborative computational and experimental workflow, synthesising the material in the laboratory, using synchrotron techniques to determine its structure, and demonstrating it in a battery cell. Their disruptive design approach offers a new route to discover more high-performance materials that rely on the fast motion of ions in solids.
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Jan 2025
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I07-Surface & interface diffraction
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Jorid
Smets
,
Victor
Rubio-Gimenez
,
Jesus
Gandara-Loe
,
Jonas
Adriaenssens
,
Mario
Fratschko
,
Fabian
Gasser
,
Roland
Resel
,
Anita
Brady-Boyd
,
Rajeshreddy
Ninakanti
,
Steven
De Feyter
,
Silvia
Armini
,
Rob
Ameloot
Diamond Proposal Number(s):
[31693, 33460]
Abstract: Integrating metal–organic frameworks (MOFs) into microfabrication processes will benefit from controlled vapor-phase deposition techniques. This study presents a molecular layer deposition method that enables area-selective and oriented growth of zeolitic imidazolate framework-8 (ZIF-8) films. Substrates functionalized with self-assembled monolayers (SAMs) with different end groups (alkyl, phenyl, hydroxyl, carboxyl, amine, and imidazole) allow tuning the degree of crystallographic orientation in the resulting MOF layers. Spatial control over SAM formation determined the surface mobility of the ZIF-8 building blocks, which enabled area-selective deposition.
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Jan 2025
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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Clorice R.
Reinhardt
,
Juliet A.
Lee
,
Lauren
Hendricks
,
Tierani
Green
,
Lily
Kunczynski
,
August Jaunzarins
Roberts
,
Naomi
Miller
,
Noga
Rafalin
,
Heather J.
Kulik
,
Christopher J.
Pollock
,
Rachel N.
Austin
Diamond Proposal Number(s):
[34781]
Abstract: Alkane monooxygenase (AlkB) is the dominant enzyme that catalyzes the oxidation of liquid alkanes in the environment. Two recent structural models derived from cryo-electron microscopy (cryo-EM) reveal an unusual active site: a histidine-rich center that binds two iron ions without a bridging ligand. To ensure that potential photoreduction and radiation damage are not responsible for the absence of a bridging ligand in the cryo-EM structures, spectroscopic methods are needed. We present the results of extended X-ray absorption fine structure (EXAFS) experiments collected under conditions where photodamage was avoided. Careful data analysis reveals an active site structure consistent with the cryo-EM structures in which the two iron ions are ligated by nine histidines and separated by at least 5 Å. The EXAFS data were used to inform structural models for molecular dynamics (MD) simulations. The MD simulations corroborate EXAFS observations that neither of the two conserved carboxylate-containing residues (E281 and D190) near the active site are likely candidates for metal ion bridging. Mutagenesis experiments, spectroscopy, and additional MD simulations were used to further explore the role of these carboxylate residues. A variant in which a carboxylate containing residue (E281) was changed to a methyl residue (E281A) showed little change in pre-edge features, consistent with the observation that it is not essential for activity and hence unlikely to serve as a bridging ligand at any point in the catalytic cycle. D190 variants had substantially diminished activity, suggesting an important role in catalysis not yet fully understood.
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Jan 2025
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[36844]
Open Access
Abstract: A series of novel chain-extended polyurethanes (CEPUs) featuring degradable sulfonyl ethyl urethane chain-extenders that permit degradation under base-triggered conditions to afford “debond-on-demand” elastomeric adhesives are reported. Exposure of the CEPUs to tetra-butylammonium fluoride (TBAF) triggered the degradation of the sulfonyl ethyl urethane chain-extenders. Lap shear adhesion tests of the CEPUs exposed to TBAF revealed reductions in shear strength of up to 65% for both aluminum and glass substrates, from 2.18 to 0.76 MPa and from 1.13 to 0.52 MPa, respectively. The selective depolymerization of these polymers makes them suitable candidates as debondable binders for inkjet inks and coatings, enabling removal of inks and adhesive residues from substrates before they enter the recycling process, to prevent surface contaminants decreasing the quality of the recycled material.
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Jan 2025
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I24-Microfocus Macromolecular Crystallography
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Shangwen
Luo
,
Xin-Rong
Li
,
Xiao-Tong
Gong
,
Alexey
Kulikovsky
,
Feng
Qu
,
Konstantinos
Beis
,
Konstantin
Severinov
,
Svetlana
Dubiley
,
Xinxin
Feng
,
Shi-Hui
Dong
,
Satish K.
Nair
Abstract: Infections caused by gram-negative pathogens continue to be a major risk to human health because of the innate antibiotic resistance endowed by their unique cell membrane architecture. Nature has developed an elegant solution to target gram-negative strains, namely by conjugating toxic antibiotic warheads to a suitable carrier to facilitate the active import of the drug to a specific target organism. Microcin C7 (McC) is a Trojan horse peptide–conjugated antibiotic that specifically targets enterobacteria by exploiting active import through oligopeptide transport systems. Here, we characterize the molecular mechanism of McC recognition by YejA, the solute binding protein of the Escherichia coli oligopeptide transporter. Structure-guided mutational and functional analysis elucidates the determinants of substrate recognition. We demonstrate that the peptide carrier can serve as a passport for the entry of molecules that are otherwise not taken into E. coli cells. We show that peptide conjugation can remodel the antibiotic spectrum of clinically relevant parent compounds. Bioinformatics analysis reveals a broad distribution of YejA-like transporters in only the Proteobacteria, underscoring the potential for the development of Trojan horse antibiotics that are actively imported into such gram-negative bacteria.
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Jan 2025
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