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Adsorbate-induced formation of a surface-polarity-driven nonperiodic superstructure
Get PDFFunding: . C.M.Y. and P.W. acknowledge support from EPSRC (EP/S005005/1). C.M.Y. acknowledges additional support from the Ministry of Science and Technology of China (2022YFA1402702, 2021ZD0302700) and TDLI Start-up Fund. A.P.M. acknowledges support from the MPG. This work used the Cirrus UK National Tier-2 HPC Service at EPCC funded by the University of Edinburgh and EPSRC (EP/P020267/1), as well as the HPC cluster Hypatia of the University of St Andrews.The chemical and electronic properties of surfaces and interfaces are important for many technologically relevant processes, be it in information processing, where interfacial electronic properties are crucial for device performance, or in catalytic processes, which depend on the types and densities of active nucleation sites for chemical reactions. Quasi-periodic and nonperiodic crystalline surfaces offer new opportunities because of their inherent inhomogeneity, resulting in localisation and properties vastly different from those of surfaces described by conventional Bravais lattices. Here, we demonstrate the formation of a nonperiodic tiling structure on the surface of the frustrated antiferromagnet PdCrO2 due to hydrogen adsorption. The tiling structure exhibits no long-range periodicity but comprises few-atom hexagonally packed domains covering large terraces. Measurement of the local density of states by tunnelling spectroscopy reveals adsorption-driven modifications to the quasi-2D electronic structure of the surface layer, showing exciting opportunities arising from electron localisation.Peer reviewe
Provenance visualization as an entry point to the history and curation of information collections
Get PDFProvenance—the origin and production methods of an artifact or piece of information—is an essential part across allfields of knowledge production. Its disclosure ensures authenticity, reproducibility, and transparency. While digital tools can automate provenance tracking and disclosure, the amount and complexity of provenance information presents a challenge, particularly within the context of cultural collections, where physically-born artifacts are transformed into digital space. This process introduces a number of methodological and curatorial decisions that, in turn, can have a grave influence on how the—once physical—collection is represented and how it will be interpreted. In previous work, we have started to address this issue by introducing provenance-driven visualization as an approach to provenance disclosure that (1) traces and categorizes both the physical and digital provenance of information collections (e.g., transcriptions, modifications of content and structure, ex/inclusion of information items) and (2) utilizes visualization to disclose and make provenance explorable in interactive ways. While this approach has shown potential, there are challenges to designing provenance-driven visualizations which can be perceived as complex and abstract and, ultimately, a distraction from the information collections’ content. How can visualization design navigate tensions between making visible provenance information and underlying curatorial decisions in a holistic and compact way, while enabling easy entry points to and promoting the critical interpretation of the collection’s content? In this paper, we present a novel design approach to provenance-driven visualization that combines abstract visualization, textual descriptions, and representations of artifactual form with storytelling techniques to introduce provenance information. Our findings from a qualitative study demonstrate the success of this approach in (1) providing a visual entry point into the collection’s provenance, (2) promoting an in-depth understanding of the transitions and underlying curatorial decisions thecollection has gone through, all the while (3) positively influencing the collections’ content exploration and its critical interpretation. Our work contributes new perspectives on how visualization can be applied to add transparency and to raise awareness of the constructed and situated nature of data, in particular, in the context of cultural collections, but also beyond.Peer reviewe
Layered oxide positive electrode materials for high energy sodium ion batteries
No full textAbstract redacted"This work was supported by the Faraday Institution (grant numbers FIRG018, FIRG064), the EPSRC Light Element Analysis Facility Grant EP/T019298/1, and the EPSRC Strategic Equipment Resource Grant EP/R023751/1, Core Equipment Grant: EP/V034138/1. The soft x-ray absorption and RIXS experiments were performed at BL27SU of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal Nos. 2021B1587 Nos. 2021B1587 and 2023B1736)."--Fundin
Investigating cognitive processes in different item formats in reading tests through eye-tracking and verbal protocols
Get PDFThis study has investigated the differences in cognitive processes that test-takers undergo while answering reading comprehension questions in multiple-choice and open-ended short answer formats. For this purpose, data were collected from a group of undergraduate students in an English medium university through eye-tracking technology, immediate retrospective verbal protocols, and short semi-structured interviews. The results showed that the participants used careful reading skills more and comprehended the text more thoroughly in the open-ended format. However, in the MC format, they read less carefully and used more test-taking strategies. These findings contribute to the ongoing discussion on how item format can alter the cognitive processes in a reading comprehension test and confirm the effectiveness of eye-tracking in unveiling cognitive processes in combination with qualitative methods. This study has implications for reading test development.Peer reviewe
Longitudinally asymmetric stratospheric oscillation on a tidally locked exoplanet
Get PDFFunding: The authors gratefully acknowledge the funding and support provided by the Edinburgh Earth, Ecology, and Environmental Doctoral Training Partnership and the Natural Environment Research Council [grant No. NE/S007407/1]. We also kindly acknowledge our use of the Monsoon2 system, a collaborative facility supplied under the Joint Weather and Climate Research Programme, a strategic partnership between the Met Office and the Natural Environment Research Council. Our research was performed as part of the project "Using UKCA to investigate atmospheric composition on extra-solar planets (ExoChem)." This work was partly funded by the Leverhulme Trust through a research project grant [RPG-2020-82], a Science and Technology Facilities Council Consolidated Grant [ST/R000395/1] and a UKRI Future Leaders Fellowship [grant No. MR/T040866/1]. J.M. and I.A.B. acknowledge the support of a Met Office Academic Partnership secondment.Using a three-dimensional general circulation model, we show that the atmospheric dynamics on a tidally locked Earth-like exoplanet, simulated with the planetary and orbital parameters of Proxima Centauri b, support a longitudinally asymmetric stratospheric wind oscillation (LASO), analogous to Earth's quasi-biennial oscillation (QBO). In our simulations, the LASO has a vertical extent of 35–55 km, a period of 5–6.5 months, and a peak-to-peak wind speed amplitude of −70 to +130 m s−1 with a maximum at an altitude of 41 km. Unlike the QBO, the LASO displays longitudinal asymmetries related to the asymmetric thermal forcing of the planet and to interactions with the resulting stationary Rossby waves. The equatorial gravity wave sources driving the LASO are localized in the deep convection region at the substellar point and in a jet exit region near the western terminator, unlike the QBO, for which these sources are distributed uniformly around the planet. Longitudinally, the western terminator experiences the highest wind speeds and undergoes reversals earlier than other longitudes. The antistellar point only experiences a weak oscillation with a very brief, low-speed westward phase. The QBO on Earth is associated with fluctuations in the abundances of water vapor and trace gases such as ozone, which are also likely to occur on exoplanets if these gases are present. Strong fluctuations in temperature and the abundances of atmospheric species at the terminators will need to be considered when interpreting atmospheric observations of tidally locked exoplanets.Peer reviewe
Anecdotal observations of socially learned vocalizations in harbor seals
Get PDFFunding: Danish National Research Foundation, Grant/Award Number: DNRF117. The Comparative Bioacoustics Group is funded by Max Planck Group Leader funding to A.R.Harbor seals (Phoca vitulina) are more solitary and less vocally complex than many other pinnipeds. Yet, they are capable of vocal learning, a form of social learning. Most extant literature examines social animals when investigating social learning, despite sociality not being a prerequisite. Here, we report two formerly silent harbor seals who initiate vocalizations, after having repeatedly observed a conspecific receiving food rewards for vocalizing. The novel vocalizations were then successfully trained to be associated with cues. Our observations suggest both social and vocal learning in a group of captive harbor seals, a species that lives semi-solitarily in the wild. We propose that, in this case, social learning acted as a shortcut to acquiring food rewards compared to the comparatively costly asocial learning.Peer reviewe
Exploring metastable states in UO2 using hybrid functionals and dynamical mean field theory
Get PDFFunding: LER acknowledges an EPSRC Early Career Research Fellowship (EP/P033253/1) and the Thomas Young Centre under Grant Number TYC-101. An award of computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. This research used resources of the Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357. We are also grateful to the UK Materials and Molecular Modelling Hub for computational resources, which is partially funded by EPSRC (EP/P020194/1), while calculations were also performed on the Imperial College High Performance Computing Service and the ARCHER UK National Supercomputing Service. HP and PBL acknowledge funding from the US Department of Energy, Office of Science, Basic Energy Sciences Division of Materials Sciences and Engineering. HP gratefully acknowledges the computing resources provided on Bebop, high-performance computing clusters operated by the Laboratory Computing Resource Center at Argonne National Laboratory. Los Alamos National Laboratory is managed by Triad National Security, LLC, for the National Nuclear Security Administration of the U.S. Department of Energy under Contract No. 89233218CNA000001.A detailed exploration of the f-atomic orbital occupancy space for UO2 is performed using a first principles approach based on density functional theory (DFT), employing a full hybrid functional within a systematic basis set. Specifically, the PBE0 functional is combined with an occupancy biasing scheme implemented in a wavelet-based algorithm which is adapted to large supercells. The results are compared with previous DFT + U calculations reported in the literature, while dynamical mean field theory is also performed to provide a further base for comparison. This work shows that the computational complexity of the energy landscape of a correlated f-electron oxide is much richer than has previously been demonstrated. The resulting calculations provide evidence of the existence of multiple previously unexplored metastable electronic states of UO2, including those with energies which are lower than previously reported ground states.Peer reviewe
Flaring efficiencies and NOx emission ratios measured for offshore oil and gas facilities in the North Sea
Get PDFFunding: This work was supported by the Climate and Clean Air Coalition (CCAC) Oil and Gas Methane Science Studies (MSS) hosted by the United Nations Environment Programme. Funding was provided by the Environmental Defense Fund, the Oil and Gas Climate Initiative, the European Commission, and the CCAC (grant no. DTIE19-020). The aircraft data used in this publication were collected as part of two projects: the Demonstration Of A Comprehensive Approach To Monitoring Emissions From Oil and Gas Installations (AEOG) project (grant no. NE/R01451X/1) and the Methane Observations and Yearly Assessment (MOYA) project (grant no. NE/N015835/1), both funded by the Natural Environment Research Council (NERC).Gas flaring is a substantial global source of carbon emissions to atmosphere and is targeted as a route to mitigating the oil and gas sector carbon footprint due to the waste of resources involved. However, quantifying carbon emissions from flaring is resource-intensive, and no studies have yet assessed flaring emissions for offshore regions. In this work, we present carbon dioxide (CO2), methane (CH4), ethane (C2H6), and NOx (nitrogen oxide) data from 58 emission plumes identified as gas flaring, measured during aircraft campaigns over the North Sea (UK and Norway) in 2018 and 2019. Median combustion efficiency, the efficiency with which carbon in the flared gas is converted to CO2 in the emission plume, was 98.4 % when accounting for C2H6 or 98.7 % when only accounting for CH4. Higher combustion efficiencies were measured in the Norwegian sector of the North Sea compared with the UK sector. Destruction removal efficiencies (DREs), the efficiency with which an individual species is combusted, were 98.5 % for CH4 and 97.9 % for C2H6. Median NOx emission ratios were measured to be 0.003 ppm ppm−1 CO2 and 0.26 ppm ppm−1 CH4, and the median C2H6:CH4 ratio was measured to be 0.11 ppm ppm−1. The highest NOx emission ratios were observed from floating production storage and offloading (FPSO) vessels, although this could potentially be due to the presence of alternative NOx sources on board, such as diesel generators. The measurements in this work were used to estimate total emissions from the North Sea from gas flaring of 1.4 Tg yr−1 CO2, 6.3 Gg yr−1 CH4, 1.7 Gg yr−1 C2H6 and 3.9 Gg yr−1 NOx.Peer reviewe
Red and near-infrared thermally activated delayed fluorescence emitters based on a dibenzo[f,h]pyrido[2,3-b]quinoxaline acceptor
Get PDFFunding: F. N. thanks London South Bank University (LSBU) and Edinburgh Instruments for a PhD studentship. C. S. thanks the China Scholarship Council (201806890001). The authors acknowledge support from the UK′s Engineering and Physical Sciences Research Council (grants EP/P010482/1 and EP/L017008/1).Recently, there has been growing interest in deep red (DR) and near-infrared (NIR) thermally activated delayed fluorescence (TADF) emitters due to their potential use in applications in bioimaging and night-vision displays. Herein, we designed and synthesized a series of red/NIR TADF emitters, DMAC , PXZ , and DPACz , that all contain the same electron-accepting PyBP (dibenzo [f, h] pyrido [2,3-b]quinoxaline) moiety. These compounds emit at 643 nm for DMACPyBP , 722 nm for DPACz PyBP , and 743 nm for PXZPyBP in toluene solution, while their thin films singlet-triplet energy gaps (ΔEST) are <0.1 eV. DMACPyBP , with the weakest donor, has the highest ΦPL of 62.3 %, the smallest ΔEST of 0.03 eV, and a fast reverse intersystem crossing rate constant (kRISC) of 0.5×105 s−1 in a 1 wt% doped film in CBP. In contrast, PXZPyBP , containing the strongest donor, has a lower ΦPL (21.2 %), a relatively larger ΔEST (0.10 eV), and a slower kRISC (0.04×105 s−1). Thus, our work highlights the molecular design challenges involved in pushing emission into the NIR region while maintaing both TADF and high ΦPL in PyBP-based donor-acceptor emitters.Peer reviewe
Applying a unified framework to compare taxonomic, functional and phylogenetic diversity in Holocene pollen records
Get PDFFunding: Natural Environment Research Council, Grant/Award Number: NERC-MOST NE/T004487/1; Leverhulme Trust, Grant/Award Number: RPG-2019-402; National Science and Technology Council, Taiwan, Grant/Award Number: NSTC-111-2118M-007-00.1. Biodiversity is multifaceted, encompassing taxonomic, phylogenetic and functional dimensions of biological variation. Long‐term studies which compare these dimensions across a range of environments elucidate ecosystem dynamics and responses to environmental change. A recently developed quantitative framework allows measurement of taxonomic, phylogenetic and functional diversity in equivalent, abundance‐sensitive units, so that these three dimensions of diversity can be directly compared. This framework has been implemented for both alpha diversity (iNEXT.3D) and beta diversity (iNEXT.Beta3D). 2. We adapt this framework for application to pollen records, a major source of data on long‐term ecological change. To the best of our knowledge, this is the first application of the new framework to pollen records. We used the framework to compare dimensions of diversity during shifts in woodland extent and composition in northern Scotland, focusing on two sites with contrasting climatic and vegetation histories. These records capture responses to c. 8000 years of climatic and land‐use change. 3. We found that despite persistent woodland cover, the less exposed site exhibits large variations in taxonomic, phylogenetic and functional diversity and composition, including a decline across all dimensions of diversity since 1200 cal year BP. Since around 7500 cal year BP, the exposed site shows more stable biodiversity across all three dimensions. We attribute these differing dynamics to habitat heterogeneity at the less exposed site and slow ecological processes (e.g. peat expansion and regeneration failure in trees) at the exposed site. The results show that diversity responses to changing or persistent woodland cover varied across the three dimensions of diversity and also for rare, abundant and dominant groups. These responses are not detected through conventional analyses of taxonomic richness. 4. Synthesis. Evaluating long‐term diversity patterns in an integrated framework allows direct comparison of taxonomic, functional and phylogenetic diversity patterns, and generates insights of potential relevance to ecosystem management. Across multiple dimensions, changes in diversity and composition are evident despite woodland persistence, and long‐term site‐specific ecological processes strongly influence diversity dynamics. By applying the framework to pollen data, and demonstrating that this yields insights into long‐term diversity change, our work supports broader application of this method to palaeoecological records.Peer reviewe
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