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A microfocus study on basic-oxygen-furnace slag thin sections to understand the principles of vanadium incorporation
No full textVanadium in basic-oxygen-furnace (BOF) slags is particularly interestingregarding the recovery of this element, which has been further strengthened byits inclusion in the list of critical raw materials by the European Union in 2017.As BOF slags can have a significant vanadium content, they continue to be apromising secondary vanadium source. Therefore, the binding mechanisms ofvanadium in the respective slag minerals must be fundamentally understood toadapt a recovery process, which enables a sufficient yield and is environmentallyfriendly and resource-saving. This study presents a synchrotron chemical-imaging investigation based on a combined micro X-ray fluorescence, microX-ray diffraction and micro X-ray absorption near-edge structure analysis,enabling new insights into vanadium incorporation in BOF slags. In contrast tothe previously assumed incorporation of vanadium directly into the calciumsilicates, it was shown that vanadium accumulates in their boundary regions astetrahedral V5+ in a structure deviating from calcium silicates. This structure ismost likely a poorly crystalline residuum consisting mainly of calcium, siliconand vanadium (and oxygen) but shows no evidence of a glass phase. Addi-tionally, vanadium occurs as octahedral V4+ in calcium ferrites and as tetra-hedral V5+ in very small quantities directly in the calcium silicates. Thesignificant enrichment of vanadium in the boundary regions of calcium silicatestogether with the high oxidations states, resulting in high mobility, can beregarded as advantageous for future recycling strategie
Search for same-charge top-quark pair production in pp collisions at = 13 TeV with the ATLAS detector
No full textA search for the production of top-quark pairs with the same electric charge (tt or ) is presented. The analysis uses proton-proton collision data at = 13 TeV, recorded by the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb. Events with two same-charge leptons and at least two b-tagged jets are selected. Neural networks are employed to define two selections sensitive to additional couplings beyond the Standard Model that would enhance the production rate of same-sign top-quark pairs. No significant signal is observed, leading to an upper limit on the total production cross-section of same-sign top-quark pairs of 1.6 fb at 95% confidence level. Corresponding limits on the three Wilson coefficients associated with the , , and operators in the Standard Model Effective Field Theory framework are derived.[graphic not available: see fulltext
Orbital and Spin Reconstruction by Interface Symmetry Engineering in Oxide Superlattices
No full textPhase transitions in transition metal oxides, particularly those involving charge, orbital, and spin order, give rise to emergent electronic and magnetic phenomena, making these materials critical to the advancement of spintronics and quantum technologies. SrRuO (SRO) and LaNiO (LNO) have distinct physical properties. SRO is characterized by its metallic conductivity, ferromagnetism, and strong spin polarization, while LNO exhibits pronounced electron correlations and sensitivity to structural distortion. However, advancements in fabrication techniques and interface engineering have made it easier to integrate these materials into combined systems. In this work, the [5 nm SRO/t nm LNO]₁₀ superlattices are explored, where the interfacial coupling mechanisms give rise to intriguing electronic phenomena such as charge transfer, orbital hybridization, and spin rearrangement. The thickness-dependent X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) reveal a Ru-to-Ni charge transfer. Additionally, X-ray linear dichroism (XLD) measurements demonstrate reduced structural disorder and enhanced Ru-4d/Ni-3d orbital hybridization, mediated by O-2p states. This study addresses key challenges in developing functional oxide superlattices using mechanisms such as charge transfer, orbital hybridization, and spin reconstruction which offer new pathways for their application in next-generation spintronic devices and quantum materials
EVAluation of the Equivalent Vector Boson Approximation at highest energy colliders
No full textCollider processes at the highest available partonic center-of-mass energies - 10 TeV and above - exhibit a new regime of electroweak interactions where electroweak gauge bosons mostly act as quasi-massless partons in vector boson fusion processes. We scrutinize these processes using the Equivalent Vector boson Approximation (EVA) based on its implementation in the Monte Carlo generator framework Whizard. Using a variety of important physics processes, including top pairs, Higgs pairs, neutrino pairs, and vector boson pairs, we study the behavior of processes initiated by transverse and longitudinal vector bosons, both and induced. The flexibility of our framework allows to study such processes at different high-energy colliders, such as a muon collider or a high-energy proton collider like FCC-hh. Studying a set of differential distributions, we show which scale choices are the most preferable ones to best approximate results based on full matrix elements
Fermi surfaces of the nodal-line candidates CaCdGe and CaCdSn: Discrepancy between band structure calculations and quantum oscillation measurements
No full textNodal-line semimetals are characterized by one-dimensional lines or loops of topologically protected band-touching nodes. For two recent nodal-line semimetal candidates, CaCdGe and CaCdSn, band structure calculations show nontopological and topological valence bands with the nodal band crossings above the Fermi level. Here, we present our investigation of the Fermi surfaces of CaCdGe and CaCdSn by use of de Haas–van Alphen measurements and band structure calculations. Our measurements reveal many quantum oscillation frequencies that are not predicted by calculations. This discrepancy casts doubt on the calculated band structures and, thus, on the precise nature of the topology of these systems
The molecular basis for acetylhistidine synthesis by HisAT/NAT16
No full textAcetylhistidine has been detected in human blood, but its origin and function are not known. It is formed when the acetyl group of acetyl-CoA is transferred to the α-amino group of histidine. Here we identify the intracellular NAT16 as the human histidine acetyltransferase (HisAT) responsible for histidine acetylation in vitro and in vivo. A NAT16 variant (p.Phe63Ser) present in over 5% of the population was previously found to correlate with reduced plasma levels of acetylhistidine and increased risk of kidney disease. Our biochemical analysis of HisAT/NAT16 Phe63Ser shows reduced affinity for Histidine supporting a model where this variant has less acetylhistidine catalysis leading to lower blood level of acetylhistidine. We find that HisAT adopts a double-GNAT (Gcn5-related N-Acetyltransferase) fold where the N-terminal domain binds acetyl-CoA and with distinct active site conformation allowing the binding of histidine in between the two domains. We detect similar structures from across living organisms and find that the HisAT structure is conserved in several archaeal and bacterial species. In sum, NAT16 is the human histidine acetyltransferase utilizing a rare double-GNAT structure to steer plasma acetylhistidine levels with potential impact for kidney function
Real-time probing of the interplay between spinodal decomposition and crystallization during morphological evolution in printed organic solar cells
No full textThe performance of organic solar cells (OSCs) strongly depends on the phase separation and crystalline properties within the active layer. However, the lack of deep understanding of morphological evolution, particularly regarding spinodal decomposition and crystallization mechanisms, presents substantial challenges in achieving precise morphological control. In this work, we systematically investigate the film formation of PBDB-TF-TTz: BTP-4F-24 blends during slot-die coating while comparing o-xylene and chlorobenzene (CB) as solvents to create distinct polymer/solvent/non-solvent systems. The complex interplay between the spinodal decomposition and crystallization processes is elucidated through complementary in situ grazing incidence small-angle X-ray scattering (GISAXS) and in situ grazing incidence wide-angle X-ray scattering (GIWAXS) together with the calculation of spinodal curves. Our findings indicate that CB-processed active layers generate larger initial clusters, promoting domain coarsening while suppressing crystallization. In contrast, o-xylene-processed films exhibit optimized phase separation, larger crystallites, and face-on molecular orientations, enhancing charge transport. Additionally, polymer-dominated thermodynamic and kinetic evolution plays a critical role in shaping out the final morphology. Consequently, OSCs fabricated with o-xylene achieve higher power conversion efficiency than those processed with CB. These insights enrich the understanding of morphological evolution and provide valuable guidelines for morphology optimization
3D Electron Diffraction as GIWAXS Alternative for Quantitative Structural Characterization of Organic Solar Cells
No full textWe demonstrate elastically filtered 3D Electron Diffraction (3D ED) as a powerful alternative technique to Grazing Incidence Wide-Angle X-ray Scattering (GIWAXS) for quantitatively characterizing the structure of organic semiconductor films. Using a model material system of solvent vapor annealed DRCN5T:PC71BM thin film, which is employed in organic solar cells (OSCs), we extract the structural data obtained from 3D ED and compare with that from GIWAXS, utilizing both laboratory and synchrotron X-ray sources. Quantitative evaluation of the datasets in terms of peak positions, peak widths and mosaicity revealed good agreement between both techniques, qualifying 3D ED as an alternative tool for analyzing highly beam-sensitive organic thin films. Furthermore, the respective advantages and limitations of 3D ED and GIWAXS are discussed, emphasizing the unique capability of 3D ED to integrate seamlessly with the diverse imaging and spectroscopic modalities in modern TEM. This integration enriches the techniques of structural characterization of OSCs, paving the way for deeper insights into their structural properties and ultimately their performance
Avoiding the formation of pores during laser welding of copper hairpins by dynamic beam shaping
No full textAny pores formed during laser welding of copper hairpins affect the structural integrity and the mechanical/electrical functionality of the joint. We report on investigations using synchrotron X-ray imaging techniques to observe the formation of the pores in the processing zone while welding. It was found that all pores are formed at the joint gap and that the small pores are distributed throughout the complete joint volume as a result of the melt flow induced by the movement of the laser beam. This insight has led to the development of a welding strategy that minimizes pore formation by avoiding the movement of the laser beam across the joint gap. This was achieved by rapid beam shaping based on coherent beam combining (CBC) technology
Parkinson-like wild-type superoxide dismutase 1 pathology induces nigral dopamine neuron degeneration in a novel murine model
No full textAtypical wild-type superoxide dismutase 1 (SOD1) protein misfolding and deposition occurs specifically within the degenerating substantia nigra pars compacta (SNc) in Parkinson disease. Mechanisms driving the formation of this pathology and relationship with SNc dopamine neuron health are yet to be fully understood. We applied proteomic mass spectrometry and synchrotron-based biometal quantification to post-mortem brain tissues from the SNc of Parkinson disease patients and age-matched controls to uncover key factors underlying the formation of wild-type SOD1 pathology in this disorder. We also engineered two of these factors - brain copper deficiency and upregulated SOD1 protein levels - into a novel mouse strain, termed the SOCK mouse, to verify their involvement in the development of Parkinson-like wild-type SOD1 pathology and their impact on dopamine neuron health. Soluble SOD1 protein in the degenerating Parkinson disease SNc exhibited altered post-translational modifications, which may underlie changes to the enzymatic activity and aggregation of the protein in this region. These include decreased copper binding, dysregulation of physiological glycosylation, and atypical oxidation and glycation of key SOD1 amino acid residues. We demonstrated that the biochemical profile introduced in SOCK mice promotes the same post-translational modifications and the development of Parkinson-like wild-type SOD1 pathology in the midbrain and cortex. This pathology accumulates progressively with age and is accompanied by nigrostriatal degeneration and dysfunction, which occur in the absence of α-synuclein deposition. These mice do not exhibit weight loss nor spinal cord motor neuron degeneration, distinguishing them from transgenic mutant SOD1 mouse models. This study provides the first in vivo evidence that mismetallation and altered post-translational modifications precipitates wild-type SOD1 misfolding, dysfunction, and deposition in the Parkinson disease brain, which may contribute to SNc dopamine neuron degeneration. Our data position this pathology as a novel drug target for this disorder, with a particular focus on therapies capable of correcting alterations to SOD1 post-translational modifications