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Exploring the impact of the presence of 9,9’-spirobifluorene moieties on the performance of carbonyl-based multiresonant thermally activated delayed fluorescence organic light-emitting diodes
Get PDFFunding: S.W. thanks the China Scholarship Council (201906250199). The authors acknowledge support by the state of Baden-Württemberg through bwHPC and the German Research Foundation (DFG) through grant no INST 40/575-1 FUGG (JUSTUS 2 cluster). This project has been partly funded by the European Union Horizon 2021 research and innovation programme under grant agreement No. 101073045 (TADFsolutions) and the EPSRC grant EP/X026175/1. We thank the EPSRC (EP/Z535291/1, EP/W007517/1, and EP/W015137/1) for financial support.The impact of the decoration of the multiresonant thermally activated delayed fluorescence (MR-TADF) core DiKTa with 9,9′-spirobifluorene (SBF) groups is investigated with respect to the impact of number, position, and incorporation-type of the SBF unit on the photophysical and optoelectronic properties. This approach allows for the development of narrowband, high-efficiency organic light emitting diodes (OLEDs) with moderate efficiency roll-off. The MR-TADF emitters DiKTaSBF , 3-SBF-DiKTa , 7-SBF-DiKTa , and 7-SBF-DiKTaSBF , differ in the number, position, and incorporation-type of the SBF unit. Sky-blue OLEDs with DiKTaSBF and 3-SBF-DiKTa show superior performance with maximal external quantum efficiencies (EQEmax) of 26.1 and 27.0%, respectively, while all four families of OLEDs show a moderate efficiency roll-off. Narrowband emissions with full-width at half maximum (FWHM) of 32 and 35 nm are observed for 7-modified emitters, whereas for the devices with emitters containing SBF groups at the 3-position show a broadened emission, with FWHM of ≈50 nm. These findings highlight the effect of the regiochemistry of the SBF group on the optoelectronic properties and the corresponding impact on the performance of the OLEDs.Peer reviewe
Probing progression of heating through the lower flare atmosphere via high-cadence IRIS spectroscopy
Get PDFFunding: J.L. and V.P. acknowledge support from NASA under the contract NNG09FA40C (IRIS). J.L. also acknowledges support from the Heliophysics Guest Investigator (H-GI) Open grant 80NSSC24K0553. V.P. also acknowledges support from NASA H-GI grant No. 80NSSC20K0716. G.S.K. acknowledges support from a NASA Early Career Investigator Program award (grant 80NSSC21K0460). L.A.H was supported by an ESA Research Fellowship during the main part of this research. She is now supported by a Royal Society-Research Ireland University Research Fellowship.Recent high-cadence flare campaigns by the Interface Region Imaging Spectrograph (IRIS) have offered new opportunities to study rapid processes characteristic of flare energy release, transport, and deposition. Here, we examine high-cadence chromospheric and transition region spectra acquired by IRIS during a C-class flare from 2022 September 25. Within the flare ribbon, the intensities of the Si ɪᴠ 1402.77 Å, C ɪɪ 1334.53 Å and Mg ɪɪ k 2796.35 Å lines peaked at different times, with the transition region Si ɪᴠ typically peaking before the chromospheric Mg ɪɪ line by 1–6 s. To understand the nature of these delays, we probed a grid of radiative hydrodynamic flare simulations heated by electron beams, thermal conduction-only, or Alfvén waves. Electron beam parameters were constrained by hard X-ray observations from the Gamma-ray Burst Monitor (GBM) onboard the Fermi spacecraft. Reproducing light curves where Si ɪᴠ peaks precede those in Mg ɪɪ proved to be a challenge because only a subset of Fermi/GBM-constrained electron beam models were consistent with the observations. Light curves with relative timings consistent with the observations were found in simulations heated by either high-flux electron beams or by Alfvén waves, while the thermal conduction heating does not replicate the observed delays. Our analysis shows how delays between chromospheric and transition region emission pose tight constraints on flare models and properties of energy transport, highlighting the importance of obtaining very high-cadence data sets with IRIS and other observatories.Peer reviewe
Exploring linear mono-, bis- and tris-acetylene containing agonists of the human olfactory receptor OR1A1
Get PDFFunding: Engineering and Physical Sciences Research Council - EP/S030506/1.Structure–activity relationship studies on olfactory receptors such as OR1A1 enhance an understanding of the molecular mechanism of olfactory perception. Such receptors are considered to be important in regulating physiological roles beyond olfactory perception. Here a series of linearized ketones, alcohols, and a cyclic ether, extended between the oxygen functionality and a terminal tert-butyl group with either mono-, bis-, or tris-acetylene spacers, was prepared to explore the response of human olfactory receptor OR1A1. The best agonists were bis-acetylene rods combined with an aryl spacer, including the bis-acetylene ketones 13 and 14 , as well as the primary aryl-bis-acetylene alcohol 20 and the corresponding secondary alcohol 21 . In the latter case, there was a clear stimulatory preference for the (R)- 21 enantiomer. The experimental data were supported by molecular docking of the various ligands on the OR1A1 homology model. Further molecular dynamics simulations revealed atomic details in the OR1A1 binding pocket.Peer reviewe
Regular bipartite multigraphs have many (but not too many) symmetries
Get PDFFunding: Research of Coen del Valle is supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), [funding reference number PGSD-577816-2023], as well as a University of St Andrews School of Mathematics and Statistics Scholarship.Let k and l be integers, both at least 2. A (k,l)-bipartite graph is an l-regular bipartite multigraph with coloured bipartite sets of size k. Define χ(k,l) and μ(k,l) to be the minimum and maximum order of automorphism groups of (k,l)-bipartite graphs, respectively. We determine χ(k,l) and μ(k,l) for k ≥ 8, and analyse the generic situation when k is fixed and l is large. In particular, we show that almost all such graphs have automorphism groups which fix the vertices pointwise and have order far less than μ(k,l). These graphs are intimately connected with both contingency tables with uniform margins and uniform set partitions; we examine the uniform distribution on the set of k × k contingency tables with uniform margin l, showing that with high probability all entries stray far from the mean. We also show that the symmetric group acting on uniform set partitions is non-synchronizing.Peer reviewe
Eocene gastropods of the New Forest, UK
Get PDFGastropods expanded into niches vacated by both terrestrial and marine organisms following the end-Cretaceous mass extinction, to become one of the dominant mollusc groups of the Cenozoic. The Selsey Formation of Eocene age was deposited within a shallow marine embayment across the Hampshire Basin (southern England) and contains a particularly diverse gastropod assemblage, forming the surface geology across the northern part of the New Forest National Park. Here, I use closely related gastropod species alive in the seas today to offer insights into the lifestyles and habitats of extinct Eocene species. By integrating this with other geological evidence, including gastropod preservation and other associated fossils, I paint a picture of the climate and environment on the New Forest seafloor during the Eocene epoch.Peer reviewe
Kin competition drives the evolution of earlier metamorphosis
Get PDFFunding: This work was supported by the China Scholarship Council (BD; studentship no. 202104910116) and the European Research Council (AG; grant no. 771387).Metamorphosis, the discrete morphological change between postembryonic life stages, is widespread across the animal kingdom. The suggested advantages of metamorphosis have usually been framed in terms of population benefits, i.e., ecological explanations. In contrast, evolutionary explanations concern whether and how metamorphosis spreads through a population owing to individual-fitness benefits. However, how kin selection modulates evolution of metamorphosis remains to be investigated formally. Here we develop a mathematical model to investigate how kin selection shapes the optimal timing of metamorphosis from foraging, non-reproductive larva to reproductive adult, when larvae tend to cluster with their genetic relatives. We consider the full range of larval competition intensities—from no competition to full competition—and the full range of relatedness coefficients—from unrelated to clonality. We provide testable predictions as to how kin selection modulates the timing of metamorphosis, as well as a conceptual framework within which empirical observations may be understood.Peer reviewe
Applications of dimension interpolation to orthogonal projections
Get PDFFunding: JMF was financially supported by a Leverhulme Trust Research Project Grant (RPG-2023-281) and an EPSRC Standard Grant (EP/Y029550/1).Dimension interpolation is a novel programme of research which attempts to unify the study of fractal dimension by considering various spectra which live in between well-studied notions of dimension such as Hausdorff, box, Assouad and Fourier dimension. These spectra often reveal novel features not witnessed by the individual notions and this information has applications in many directions. In this survey article, we discuss dimension interpolation broadly and then focus on applications to the dimension theory of orthogonal projections. We focus on three distinct applications coming from three different dimension spectra, namely, the Fourier spectrum, the intermediate dimensions, and the Assouad spectrum. The celebrated Marstrand–Mattila projection theorem gives the Hausdorff dimension of the orthogonal projection of a Borel set in Euclidean space for almost all orthogonal projections. This result has inspired much further research on the dimension theory of projections including the consideration of dimensions other than the Hausdorff dimension, and the study of the exceptional set in the Marstrand–Mattila theorem.Peer reviewe
Understanding inference
Get PDFIn this thesis I am investigating the topic of inference. This involves understanding the nature of inferential justification, namely, what grounds the transition from premises to conclusion within an inference. To achieve this, it is necessary to take a view on how logical content features in the discussion. That is, whether the entailment relation can by itself justify the inferential transition. Does the fact that p entails q justify the inference from p to q? Since inference is a matter of judgement, contemporary philosophers tend to conclude that logical content cannot perform such justification, but rather, an intermediary act is required. To take the most prominent example, rule following is put forth as such an act which can play this theoretical role.
This thesis rejects the assumption that logical content is prior to judgement. To do this, I first examine the difficulties faced by the contemporary thinkers who accept that there is such a priority. I look at two different accounts, one from Paul Boghossian (2012) and one from Crispin Wright (2014), objecting to both. I then turn to two figures, Frege and Wittgenstein, for a historical discussion of the contrast between possible perspectives. I argue that Frege, in his own way, also accepts the assumption that content is prior to judgement. Wittgenstein’s subsequent rejection of Frege’s account shines light on the problems with the assumption, still present in the contemporary debate. I defend the Tractarian view of the relation between content and judgement, that content is fundamentally of a kind to be judged. In arguing for such a view of this historical debate, I also argue for a particular way forward with the contemporary debate
Multilingualism, mourning, and (m)other tongues : women writing exile in transnational autofiction
No full textIn my thesis, Multilingualism, Mourning, and (M)Other Tongues: Women Writing Exile in Transnational Autofiction, I analyse autofictional texts by transnational writers Jessica Au, Nina Bouraoui, Claudia Durastanti, Assia Djebar, Line Papin, Kim Thúy, and Fatima Daas to explore how multilingual interventions allow authors to reckon with the loss of, and emotional distance from, non-dominant languages. Whilst they write predominantly in hegemonic languages, namely French, English, and Italian, these authors also attest to the absence-presence of the voices and languages of others in their texts, such as Vietnamese and Algerian Arabic. I thus extend the definition of multilingual texts to encompass those which gesture towards absence and the loss of language, as well as those which are more overtly multilingual. Drawing on trauma and sound studies, as well as poststructuralist and postcolonial theory, I take a comparative approach to my corpus, arguing that autofiction, as a form which is liminal, lends itself to this exploration of metaphorical and geographical exile and border-crossing. Although these writers celebrate both the creativity and forms of resistance they inherit from their own mothers and female ancestors, a form of resistance which involves listening for the voice and language(s) of the other, their insistence on loss and absence evidences the painful reality of mourning place, people, and language."I would like to express my deepest gratitude to the Borzello Educational Trust. This work was also supported by The Yorkshire Ladies’ Council and the University of St Andrews Discretionary Fund."--Fundin
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