I05-ARPES
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Zhisheng
Zhao
,
Tongrui
Li
,
Peng
Li
,
Xueliang
Wu
,
Jianghao
Yao
,
Ziyuan
Chen
,
Yajun
Yan
,
Shengtao
Cui
,
Zhe
Sun
,
Yichen
Yang
,
Zhicheng
Jiang
,
Zhengtai
Liu
,
Alex
Louat
,
Timur
Kim
,
Cephise
Cacho
,
Aifeng
Wang
,
Yilin
Wang
,
Dawei
Shen
,
Juan
Jiang
,
Donglai
Feng
Diamond Proposal Number(s):
[32274]
Abstract: The kagome metal FeGe provides a rich platform for understanding the mechanisms behind competing orders, as it exhibits charge order (CO) emerging deep within the antiferromagnetic phase. To investigate the intrinsic origin of this behavior, we examine the evolution of the low-energy electronic structure across the phase transition in annealed FeGe samples using angle-resolved photoemission spectroscopy. We find no evidence supporting a conventional nesting mechanism, such as Fermi surface nesting or van Hove singularities. However, we observe two notable changes in the band structure: an electron-like band around the K point and another around the A point, both shifting upward in energy when CO forms. These findings are consistent with our density-functional theory calculations, which suggest that the charge order in FeGe is primarily driven by magnetic energy savings due to a lattice distortion involving Ge1-dimerization. Our results provide photoemission evidence supporting this novel mechanism for CO formation in FeGe, in contrast to the conventional nesting-driven mechanisms.
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Jun 2025
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Open Access
Abstract: Due to their potential applications in low-power consumption and/or multistate memory devices, multiferroic materials have attracted a lot of attention in the condensed matter community. As part of the effort to identify new multiferroic compounds, perovskite-based GdCrO3 was studied in both bulk and thin film samples. A strong enhancement of the capacitance in a field suggested ferroelectric behaviour but significant leakage and no well developed P–E hysteresis loops were observed. Measurements clearly indicate the existence of a polar phase but only below 2 K (likely connected to Gd ordering). Here the determination of the magnetic structure through neutron diffraction collected on an isotopic 160GdCrO3 sample at the WISH diffractometer at ISIS is reported. The presence of three successive magnetic phases as a function of temperature (commensurate, spin re-orientation and incommensurate phases once the Gd order), previously only seen by magnetization, is confirmed. Using the most recent guidelines for reporting the determined structures, we highlight the benefits of using such nomenclature for discussing physical properties and consider possible mechanisms and couplings that led this seemingly rather isotropic system to display the complex structures observed.
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Jun 2025
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[36775, 26668]
Open Access
Abstract: A variable-temperature and pressure single-crystal diffraction study of hybrid improper ferroelectric Sr3Sn2O7 is reported. In combination with symmetry analysis, we reveal that the application of pressure and temperature induce distinct phase transition pathways, driven by a differing response of the octahedral rotations to these stimuli. Contrary to what has been previously predicted, we observe the ferroelectric to paraelectric phase transition between 10.17(18) and 12.13(14) GPa, meaning the hybrid improper ferroelectric phase remains stable to significantly higher pressures than expected.
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Jun 2025
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Open Access
Abstract: Advancements in macromolecular crystallography, driven by improved sources and cryocooling techniques, have enabled the use of increasingly smaller crystals for structure determination, with microfocus beamlines now widely accessible. Initially developed for challenging samples, these techniques have culminated in advanced beamlines such as VMXm. Here, an in vacuo sample environment improves the signal-to-noise ratio in X-ray diffraction experiments, and thus enables the use of submicrometre crystals. The advancement of techniques such as microcrystal electron diffraction (MicroED) for atomic-level insights into charged states and hydrogen positions, along with room-temperature crystallography to observe physiological states via serial crystallography, has driven a resurgence in the use of microcrystals. Reproducibly preparing small crystals, especially from samples that typically yield larger crystals, requires considerable effort, as no one singular approach guarantees optimal crystals for every technique. This review discusses methods for generating such small crystals, including mechanical crushing and batch crystallization with seeding, and evaluates their compatibility with microcrystal data-collection modalities. Additionally, we examine sample-delivery methods, which are crucial for selecting appropriate crystallization strategies. Establishing reliable protocols for sample preparation and delivery opens new avenues for macromolecular crystallography, particularly in the rapidly progressing field of time-resolved crystallography.
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May 2025
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I04-1-Macromolecular Crystallography (fixed wavelength)
I04-Macromolecular Crystallography
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Christian
Roth
,
Olga V.
Moroz
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Suzan A. D.
Miranda
,
Lucas
Jahn
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Elena V.
Blagova
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Andrey A.
Lebedev
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Dorotea R.
Segura
,
Mary A.
Stringer
,
Esben P.
Friis
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Joao P. L.
Franco Cairo
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Gideon J.
Davies
,
Keith S.
Wilson
Diamond Proposal Number(s):
[18598]
Open Access
Abstract: Endo-galactosaminidases are an underexplored family of enzymes involved in the degradation of galactosaminogalactan (GAG) and other galactosamine-containing cationic exopolysaccharides produced by fungi and bacteria. These exopolysaccharides are part of the cell wall and extracellular matrix of microbial communities. Currently, these galactosaminidases are found in three distinct CAZy families: GH114, GH135 and GH166. Despite the widespread occurrence of these enzymes in nearly all bacterial and fungal clades, only limited biochemical and structural data are available for these three groups. To expand our knowledge of endo-galactosaminidases, we selected several sequences predicted to encode endo-galactosaminidases and produced them recombinantly for structural and functional studies. Only very few predicted proteins could be produced in soluble form, and activity against bacterial Pel (pellicle) polysaccharide could only be confirmed for one enzyme. Here, we report the structures of two bacterial and one fungal enzyme. Whereas the fungal enzyme belongs to family GH114, the two bacterial enzymes do not lie in the current GH families but instead define a new family, GH191. During structure solution we realized that crystals of all three enzymes had various defects including twinning and partial disorder, which in the case of a more severe pathology in one of the structures required the design of a specialized refinement/model-building protocol. Comparison of the structures revealed several features that might be responsible for the described activity pattern and substrate specificity compared with other GAG-degrading enzymes.
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May 2025
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I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[33049]
Open Access
Abstract: Risk management for agricultural use of digested sewage sludge requires better understanding of the behaviour and fate of contaminant metals in the plant root zone. A study employing rhizo-pot and plug-tray experiments was conducted to identify the zone near spring barley roots (Hordeum vulgare) where concentration and speciation of Cu and Zn are affected. Cu and Zn bonding environments in the root epidermis/cortex and vascular tissue were also identified. In the digested sludge-amended soil, spring barley absorbed Cu only from the immediate vicinity of the roots (<< 1 mm), but Zn was taken up from further afield (> 1 mm). In the rhizosphere Cu was predominately present as Cu(I) oxides or as Cu(II) absorbed/bonded to phosphate, whereas Zn was present as Zn(II) in inner-sphere complexes with metal oxide surfaces, as Zn(II) sulphides or Zn(II) bonded to/incorporated into carbonates. Cu taken-up by spring barley roots was largely sequestered in the root epidermis and/or cortex predominately in the coordination environments similar to those seen in the rhizosphere. Only a small proportion of the Cu was translocated into the vascular tissue (where it is in the same two bonding environments). Zn taken-up by spring barley roots was present as Zn(II) sulphides, Zn(II) absorbed to/incorporated into carbonates, or Zn(II)-organic complexes. Zn was readily translocated from roots to shoots. Better understanding of these differences in the mobility and uptake of Cu and Zn in sludge-amended agricultural soils could be used to undertake element specific risk assessments.
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May 2025
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Lewis J.
Williams
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Amy J.
Thompson
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Philipp
Dijkstal
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Martin
Appleby
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Greta
Assmann
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Florian S. N.
Dworkowski
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Nicole
Hiller
,
Chia-Ying
Huang
,
Tom
Mason
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Samuel
Perrett
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Eduard
Prat
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Didier
Voulot
,
Bill
Pedrini
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John H.
Beale
,
Michael A.
Hough
,
Jonathan A. R.
Worrall
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Robin L.
Owen
Open Access
Abstract: Serial femtosecond crystallography (SFX) exploits extremely brief X-ray free-electron laser pulses to obtain diffraction data before destruction of the crystal. However, during the pulse X-ray-induced site-specific radiation damage can occur, leading to electronic state and/or structural changes. Here, we present a systematic exploration of the effect of single-pulse duration and energy (and consequently different dose rates) on site-specific radiation damage under typical SFX room-temperature experimental conditions. For the first time in SFX we directly measured the photon pulse duration, varying from less than 10 fs to more than 50 fs, and used three pulse energies to probe in-pulse damage in two radiation-sensitive proteins: the iron-heme peroxidase DtpAa and the disulfide-rich thaumatin. While difference-map features arising from radiation damage are observed, they do not lead to significant change in refined atomic coordinates or key bond lengths. Our work thus provides experimental verification that average atomic coordinates are not significantly perturbed by radiation damage in typical SFX experiments.
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May 2025
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B21-High Throughput SAXS
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Diamond Proposal Number(s):
[31952]
Abstract: Chirality and non-covalent chemistry are essential features in the construction of complex molecular systems that constitute living organisms. The specific interactions between molecular components with defined geometric orientations enable nature’s dynamism, responsiveness, specificity, and selection. The precision with which nature controls its homochirality and functional structures inspired the design of synthetic supramolecular systems. These systems have aimed at understanding the origins of these properties and mimicking their complexity. Research in the last decades has led to many insights into synthetic and natural supramolecular polymerization processes and principles of amplification of asymmetry. However, the complexity observed in nature remains far from being understood. In particular, detailed studies of assembly mechanisms and amplification of asymmetry principles in water-compatible supramolecular systems are scarce due to the challenging contribution of hydrophobic effects leading to non-equilibrium states of supramolecular assemblies. Valuable contributions to this field have been made in recent years, including the introduction of in situ chemical modifications and dissipative non-equilibrium assembly states, leading to evolutionary features such as self-replication. This chapter introduces the concepts of supramolecular polymerization and shows the analogies between natural and synthetic systems. In particular, the influence of homochirality in natural macroscopic structures is emphasized, showing the importance of this property in water-compatible supramolecular systems. Therefore, key developments in research on the origin of homochirality and challenges for future research to understand this essential feature of life are outlined.
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May 2025
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I18-Microfocus Spectroscopy
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Clare L.
Thorpe
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Nick
Aldred
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Stuart
Creasey-Gray
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Martin C.
Stennett
,
Eperke A.
Rencz
,
Susan
Nehzati
,
Latham T.
Haigh
,
Garry
Manifold
,
Nishta
Vallo
,
Christoph
Lenting
,
Claire L.
Corkhill
,
Russell J.
Hand
Diamond Proposal Number(s):
[38045]
Open Access
Abstract: Glass ingots of lead silicate composition from the shipwreck of the Albion were studied to ascertain the chemistry and mineralogy of alteration products after exposure to seawater for 220 years. Alteration observed on natural samples was compared to that of the same glasses exposed to short-term, high temperature, laboratory dissolution tests in synthetic seawater and significant differences were observed. Alteration layers on natural samples were more chemically complex having sequestered high concentrations of elements present only at trace quantities in seawater. Electron microprobe analysis and microfocus x-ray absorption spectroscopy shows that P, most likely released by biological activity in the vicinity of the wreck, accumulated in naturally altered samples to form Pb–Ca-phosphate phases whilst Pb-sulphate phases formed in laboratory tests. Meanwhile Fe, present at < 0.3 wt % in the glass and ppb concentrations in seawater, accumulated to form Fe-silicates whilst Mg-silicates predominated in laboratory tests. Biologically induced corrosion of naturally altered samples was also considered. Experiments conducted to test barnacle settlement rates suggest that biotoxic elements within the glass, primarily Pb but potentially also Cu, Co and Ni deterred barnacle settlement. Despite this toxicity, some colonisation of the glass surface by both barnacles and bryozoan did occur and, whilst barnacles appeared to protect against chemical attack, bryozoan colonies caused increased cracking, possibly due stress created at the glass surface. Results highlight the challenges in recreating open, natural systems in laboratory settings and demonstrate that elements present at low concentrations can have a significant impact over long timescales.
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May 2025
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Krios V-Titan Krios V at Diamond
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Bin
Yang
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Durga
Devalla
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Silvia
Sonzini
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Mikael
Boberg
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Sashi
Gopaul
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Monika
Sundqvist
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Iain
Grant
,
Christopher
Jones
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Stephanie
Brookes
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Cindy
Weidauer
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Eleonora
Paladino
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Najet
Mahmoudi
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Jason
Van Rooyen
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Ana Gomes
Dos Santos
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Johanna
Laru
,
Andy
Campbell
,
Lutz
Jermutus
,
Annette
Bak
Diamond Proposal Number(s):
[31098, 37220]
Abstract: Cotadutide (Cota) is a lipidated dual GLP-1 and Glucagon receptor agonist that was investigated for the treatment of various metabolic diseases, it is designed for once daily subcutaneous (SC) administration. Invasive daily injections can result in poor patient compliance with chronic disease, and here, we demonstrate an innovative strategy of encapsulating reversible cota self-assembled fibers within an in-situ forming depot of low molecular weight poly(lactic-co-glycolic) acid (LWPLGA) for sustained delivery GLP-1 and Glucagon receptor agonist with controlled burst release. This could be a suitable alternative to other sustained delivery strategies for fibrillating peptides. We investigated a range of cationic ions (Na+, Ca2+, Zn2+) and studied their influence on the secondary structure, morphology and the monomer release profile of cota fibers. Fibers forming hierarchy structures such as twisted filament and ribbons with beta sheet secondary structure resulted in better controlled burst. The subcutaneous administration of Ca2+ fiber/LWPLGA depot formulation in rats resulted in 60-fold reduction in maximum concentration (Cmax) compared with cota immediate release (IR) SC formulation and a prolonged plasma exposure over a month with plasma half-life extended from the 10 h observed with the cota daily formulation to 100 h. This extended-release formulation also maintains smaller peak and trough fluctuation within therapeutic window, and PK modelling of repeated dose indicates this formulation could enable a possible dose frequency of 14 days in rat with assumed therapeutic concentration (ratios of the maximum concentration and the trough concentration) Cmax/Ctrough window. This new long-acting injectable (LAI) method could open the door to transforming short-life peptides with sub-optimal half-life into candidates for weekly or even monthly dosing regimens, potentially leading to novel drug products with increased patient comfort.
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Apr 2025
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