734 research outputs found

    Oxygen reduction at the silver/hydroxide-exchange membrane interface

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    A solid-state cell is used to study the electrocatalysis of oxygen reduction at the silver/hydroxide-exchange membrane interface. The catalyst/membrane interface exhibits improved performance in comparison to a catalyst/aqueous sodium hydroxide interface. Surprisingly, the half-wave potential for oxygen reduction is shown to shift 185 mV higher at the silver/hydroxide-exchange membrane interface than for the silver/aqueous hydroxide solution interface, and the exchange current density is significantly higher at 1.02 × 10−6 A m−2. On a cost per performance basis, silver electrocatalysts in a hydroxide-exchange membrane fuel cell may provide better performance than platinum in a proton-exchange membrane fuel cell. Keywords: Oxygen reduction reaction, Electrocatalyst, Alkaline membrane, Solid-state cell, Silve

    National Evaluation of the Culture Collective programme Part one: ‘Unprecedented and revitalising’ - Emerging Impacts and Ways of Working: Reflections from the first year of the Culture Collective, Reporting from Queen Margaret University March 2023

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    David Stevenson - ORCID: 0000-0002-8977-1818 https://orcid.org/0000-0002-8977-1818Anthony Schrag - ORCID: 0000-0001-8660-7572 https://orcid.org/0000-0001-8660-7572The Culture Collective is a network of 26 participatory arts projects, shaped by local communities alongside artists and creative organisations, and funded by Scottish Government emergency COVID-19 funds through Creative Scotland. This report captures a snapshot of the programme a year into their work.https://www.creativescotland.com/resources-publications/research/archive/2023/national-evaluation-of-the-culture-collective-programmepubpu

    Multipotency of Adult Hippocampal NSCs In Vivo Is Restricted by Drosha/NFIB

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    Adult neural stem cells (NSCs) are defined by their inherent capacity to self-renew and give rise to neurons, astrocytes, and oligodendrocytes. In vivo, however, hippocampal NSCs do not generate oligodendrocytes for reasons that have remained enigmatic. Here, we report that deletion of Drosha in adult dentate gyrus NSCs activates oligodendrogenesis and reduces neurogenesis at the expense of gliogenesis. We further find that Drosha directly targets NFIB to repress its expression independently of Dicer and microRNAs. Knockdown of NFIB in Drosha-deficient hippocampal NSCs restores neurogenesis, suggesting that the Drosha/NFIB mechanism robustly prevents oligodendrocyte fate acquisition in vivo. Taken together, our findings establish that adult hippocampal NSCs inherently possess multilineage potential but that Drosha functions as a molecular barrier preventing oligodendrogenesis

    Ex-situ Ge-doping of CZTS Nanocrystals and CZTSSe Solar Absorber Films

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    Cu2ZnSn(S,Se)4 (CZTSSe) is a promising material for thin-film photovoltaics however the open-circuit voltage (VOC) deficit of CZTSSe prevents device performance to exceed 13 conversion efficiency. CZTSSe is a heavily compensated material that is rich in point defects and prone to the formation of secondary phases. The landscape of these defects is complex and some mitigation is possible by employing non-stoichiometric conditions. Another route used to reduce the effects of undesirable defects is doping and alloying of the material to suppress certain defects and improve crystallization such as germanium. The majority of works deposit Ge adjacent to a stacked metallic precursor deposited by physical vapour deposition before annealing in a selenium rich atmosphere. Here we use an established hot-injection process to synthesise Cu2ZnSnS4 nanocrystals of a pre-determined composition, subsequently doped with Ge during selenisation to aid recrystallisation and reduce the effects of Sn species. Through Ge incorporation we demonstrate structural changes with negligible change in energy bandgap but substantial increase in crystallinity and grain morphology which is associated to a Ge-Se growth mechanism and gains in both VOC and conversion efficiency. We use surface energy-filtered photoelectron emission microscopy (EF-PEEM) to map the surface work function terrains and show an improved electronic landscape which we attribute to a reduction in segregation of low local effective work function (LEWF) Sn(II) chalcogenide phases

    Measurement of the inclusive jet cross-section in proton-proton collisions at √s=7 TeV using 4.5 fb−1 of data with the ATLAS detector

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    The inclusive jet cross-section is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV using a data set corresponding to an integrated luminosity of 4.5 fb−1 collected with the ATLAS detector at the Large Hadron Collider in 2011. Jets are identified using the anti-kt algorithm with radius parameter values of 0.4 and 0.6. The double-differential cross-sections are presented as a function of the jet transverse momentum and the jet rapidity, covering jet transverse momenta from 100 GeV to 2 TeV. Next-to-leading-order QCD calculations corrected for non-perturbative effects and electroweak effects, as well as Monte Carlo simulations with next-to-leading-order matrix elements interfaced to parton showering, are compared to the measured cross-sections. A quantitative comparison of the measured cross-sections to the QCD calculations using several sets of parton distribution functions is performed

    Coherent J/ψ and ψ photoproduction at midrapidity in ultra-peripheral Pb–Pb collisions at √sNN = 5.02 TeV

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    The coherent photoproduction of J/ψJ/ψ and ψ′ψ′ mesons was measured in ultra-peripheral Pb–Pb collisions at a center-of-mass energy sNN−−−√ = 5.02sNN = 5.02 TeV with the ALICE detector. Charmonia are detected in the central rapidity region for events where the hadronic interactions are strongly suppressed. The J/ψJ/ψ is reconstructed using the dilepton (l+l−l+l−) and proton–antiproton decay channels, while for the ψ′ψ′ the dilepton and the l+l−π+π−l+l−π+π− decay channels are studied. The analysis is based on an event sample corresponding to an integrated luminosity of about 233 μb−1μb−1. The results are compared with theoretical models for coherent J/ψJ/ψ and ψ′ψ′ photoproduction. The coherent cross section is found to be in a good agreement with models incorporating moderate nuclear gluon shadowing of about 0.64 at a Bjorken-x of around 6×10−46×10−4, such as the EPS09 parametrization, however none of the models is able to fully describe the rapidity dependence of the coherent J/ψJ/ψ cross section including ALICE measurements at forward rapidity. The ratio of ψ′ψ′ to J/ψJ/ψ coherent photoproduction cross sections was also measured and found to be consistent with the one for photoproduction off protons.publishedVersio

    Production of pions, kaons, and protons as a function of the relative transverse activity classifier in pp collisions at s \sqrt{s} = 13 TeV

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    Abstract: The production of π±, K±, and ( p )p is measured in pp collisions at √s = 13 TeV in different topological regions of the events. Particle transverse momentum (pT) spectra are measured in the “toward”, “transverse”, and “away” angular regions defined with respect to the direction of the leading particle in the event. While the toward and away regions contain the fragmentation products of the near-side and away-side jets, respectively, the transverse region is dominated by particles from the Underlying Event (UE). The relative transverse activity classifier, RT = NT/〈NT〉, is used to group events according to their UE activity, where NT is the measured charged-particle multiplicity per event in the transverse region and 〈NT〉 is the mean value over all the analysed events. The first measurements of identified particle pT spectra as a function of RT in the three topological regions are reported. It is found that the yield of high transverse momentum particles relative to the RT-integrated measurement decreases with increasing RT in both the toward and the away regions, indicating that the softer UE dominates particle production as RT increases and validating that RT can be used to control the magnitude of the UE. Conversely, the spectral shapes in the transverse region harden significantly with increasing RT. This hardening follows a mass ordering, being more significant for heavier particles. Finally, it is observed that the pT-differential particle ratios (p + p )/(π+ + π−) and (K+ + K−)/(π+ + π−) in the low UE limit (RT → 0) approach expectations from Monte Carlo generators such as PYTHIA 8 with Monash 2013 tune and EPOS LHC, where the jet-fragmentation models have been tuned to reproduce e+e− results
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