Defect Engineering: Graphene Gets Designer Defects

An extended one-dimensional defect that has the potential to act as a conducting wire has been embedded in another perfect graphene sheet.Comment: 2 pages, 1 figur

Desorption of hot molecules from photon irradiated interstellar ices

We present experimental measurements of photodesorption from ices of astrophysical relevance. Layers of benzene and water ice were irradiated with a laser tuned to an electronic transition in the benzene molecule. The translational energy of desorbed molecules was measured by time-of-flight (ToF) mass spectrometry. Three distinct photodesorption processes were identified - a direct adsorbate-mediated desorption producing benzene molecules with a translational temperature of around 1200 K, an indirect adsorbate-mediated desorption resulting in water molecules with a translational temperature of around 450 K, and a substrate-mediated desorption of both benzene and water producing molecules with translational temperatures of around 530 K and 450 K respectively. The translational temperature of each population of desorbed molecules is well above the temperature of the ice matrix. The implications for gas-phase chemistry in the interstellar medium are discussed.Comment: 23 pages, including 4 figures; submitted to Ap

Laboratory investigations of the interaction between benzene and bare silicate grain surfaces

Experimental results on the thermal desorption of benzene (C6H6) from amorphous silica (SiO2) are presented. The amorphous SiO2 substrate was imaged using atomic force microscopy (AFM), revealing a surface morphology reminiscent of that of interplanetary dust particles (IDPs). Temperature programmed desorption (TPD) experiments were conducted for a wide range of C6H6 exposures, yielding information on both C6H6-SiO2 interactions and the C6H6-C6H6 interactions present in the bulk C6H6 ice. The low coverage experiments reveal complicated desorption behaviour that results both from porosity and roughness in the SiO2 substrate, and repulsive interactions between C6H6 molecules. Kinetic parameters were obtained through a combination of direct analysis of the TPD traces and kinetic modelling, demonstrating the coverage dependence of both desorption energy and pre-exponential factor. Experiments were also performed whereby the pores were blocked by pre-exposure of the SiO2 to water vapour. C6H6 was observed to be adsorbed preferentially on the SiO2 film not covered by H2O at the temperature at which these experiments were performed. This observation means that intermolecular repulsion likely becomes important at smaller C6H6 exposures on grains with a H2O mantle. Kinetic modelling of C6H6 multilayer desorption yields kinetic parameters in good agreement with previous studies, with the SiO2 having little impact on the desorption beyond the first few layers.Comment: 23 pages, including 6 figures and 1 table ; Submitted to MNRA

Structural insight into SUMO chain recognition and manipulation by the ubiquitin ligase RNF4

The small ubiquitin-like modifier (SUMO) can form polymeric chains that are important signals in cellular processes such as meiosis, genome maintenance and stress response. The SUMO-targeted ubiquitin ligase RNF4 engages with SUMO chains on linked substrates and catalyses their ubiquitination, which targets substrates for proteasomal degradation. Here we use a segmental labelling approach combined with solution nuclear magnetic resonance (NMR) spectroscopy and biochemical characterization to reveal how RNF4 manipulates the conformation of the SUMO chain, thereby facilitating optimal delivery of the distal SUMO domain for ubiquitin transfer

Religious Education, Big Ideas and the study of religion(s) and worldview(s)

This is the author accepted manuscript. The final version is available from Taylor & Francis (Routledge) via the DOI in this record.This article outlines the ‘Big Ideas’ approach to curriculum reform, as applied in the ‘Principles and Big Ideas of Science Education’ project (Harlen 2010). A critical analysis follows of the outcomes of the University of Exeter’s ‘Identifying Principles and Big Ideas for Religious Education’ project, which sought to apply the same approach to Religious Education (RE) in English schools (Wintersgill 2017). This project made great headway in generating ‘Big Ideas’ to inform and improve the selection and sequencing of RE curriculum content. However, its primary focus on subject content knowledge mean that ‘Big Ideas’ about epistemology and methodology are lacking. The article recommends an additional focus on multi-disciplinary, multi-methodological, inquiry-based, reflexive learning, which would ask why, how, where and by whom our ‘knowledge’ of religion(s) and worldview(s) is generated. In this regard, the article posits four ‘Big Ideas about the study of religion(s) and worldview(s)’ to highlight the symbiotic relationship between knowledge and knower, and to reject the false dichotomy between the object of study and method of study. In so doing, it draws upon the theoretical framework underpinning the ‘RE-searchers approach’ to primary school RE, which correspondingly exemplifies how such ideas can be taught in practice.The ‘Identifying Principles and Big Ideas for Religious Education’ project was supported by the St Luke’s College Foundation (016J-086). The ‘RE-searchers: A critical dialogic approach to Religious Education in primary schools’ project was supported by the Culham St. Gabriel’s Trust and Hockerill Education Foundation