1,137 research outputs found

    Learning to lead in the 'year of the firsts' : a study of employer led mentoring for new school leaders in Scotland.

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    The study explores the process and outcome of a mentoring programme for newly appointed school leaders in a Scottish Case Study Local Authority (CSLA). This research contributes to professional knowledge and practice in school leadership as it takes an employer perspective and offers a conceptualisation of post-appointment mentoring in Scotland. This study is contextualised by two conflicting accepted realities which are reflected at a local, national and international level. Firstly, that it is widely accepted that school leadership makes a difference and secondly, due to the reported challenges of the job, the recruitment and retention of school leaders has attained crisis status in some areas. Accepting that it is important to prepare people for school leadership roles, the focus of this thesis turns to supporting teachers in the transition to headship. Mentoring is a frequently used approach in the development of school leaders but there is lack of agreement on the concept of mentoring and empirical evidence demonstrating the benefit of mentoring is inconsistent. A conceptual framework of socialisation and development is used to explore mentoring in this study. Forty-two interviews were undertaken with newly appointed headteachers and depute headteachers and their mentors with the aim to establish whether there was a consistent interpretation or implementation of the mentoring policy and whether the claims about anticipated outcomes were substantiated. Assumptions about the mentoring policy in the CSLA were tested in order to build understanding and make meaning about how mentoring worked in practice. This research suggests that experiences of formal employer-led mentoring, as operating in the CSLA, were mainly positive and valued by both mentors and mentees. Findings indicated that mentoring supported self-confidence, wellbeing, independence and effectiveness in the novice school leader, particularly in relation to leading and managing people. The policy assumptions that experienced headteachers would agree to mentor others because there were professional gains for them, and that mentoring offered something extra to other forms of leadership and management support, were supported by the findings of this study. However this research also found that there was a lack of shared understanding over the purpose of mentoring with differing views on the importance of psychosocial or career related functions. Data indicated there were differences in how primary and secondary school dyads enacted the mentoring relationship. This thesis explores the motivations for mentoring, the characteristics that make a good mentor and the place of mentoring compared to other forms of leadership preparation and support. The findings of this study indicate that mentoring in the CSLA is understood both as a form of psychosocial support and as context specific training which prepares the mentee for the role of headteacher as it exists now and socialises them into that view. A conceptualisation of mentoring as a form of initiation which supports the prevailing orthodoxy is challenged in this thesis. It is proposed that this work progresses knowledge about mentoring as it offers two models: a chronological model to explain how mentoring relationships can evolve and a model to explore the learning that takes place. Each model provides a schematic which can be challenged and adapted to help share understandings of mentoring, an umbrella term which has morphed over the centuries from Greek myth to urban mythology in the corporate human resource world. The thesis highlights tensions and ambiguities for the local education authority as it attempts to meet its legal duty for educational provision while interpreting national policy, employing teachers and meeting Government‘s expectations for schools. This study identifies the complexity over the role of the employer in managing a formal strategy which is predicated on a personal relationship; recommendations are offered which may be of significance to those with an interest in school leadership development and organisational mentoring. This research set out to advance practice in managing a real-world leadership problem. This thesis proposes that leadership development does matter in Scotland today; the scale of the task to make our public services fit–for-purpose and fit-for-purse is considerable. Tomorrow‘s leaders should be prepared for this new landscape with vision and pragmatism

    Quantification of Fe-oxidation state in mixed valence minerals: a geochemical application of EELS revisited

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    The use of TEM and electron energy loss spectroscopy to determine levels of Fe3+ in solids at nanometre spatial resolution is well established. Here we assess this technique at the energy resolution of a monochromated electron source (0.3 eV) and with the capability of simultaneously acquiring core- and low-loss spectra for absolute energy calibration of core-loss chemical shifts. Fe L 2,3-edges of four oxide standards give a characteristic energy loss near edge structure (ELNES) and the L 3-peak maxima of the spectra exhibit an energy shift of ~ 1.8 eV between ferrous (709 eV) and ferric (710.8 eV) iron. We show that diagenetic chlorites present in iron oxide loaded 'red beds' contain predominately Fe3+, based on the absolute energy position of the low signal Fe L 3-edges (centred around 710.8 eV). We also fit our standard-spectra to Fe L 2,3-edges from magnetite and maghemite nanoparticles to investigate iron site occupancy. An additional chemical shift needs to be applied to the octahedral ferrous iron site component to achieve a plausible, linear fit to the magnetite spectrum which we speculate may be due to electron hopping between the mixed valence octahedral iron sites in magnetite

    Mobile metal adatoms on single layer, bilayer and trilayer graphene: an ab initio study correlated with experimental electron microscopy data

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    The plane-wave density functional theory code CASTEP was used with the Tkatchenko-Scheffler van der Waals correction scheme and the generalized gradient approximation of Perdew, Burke, and Ernzerhof (GGA PBE) to calculate the binding energy of Au, Cr, and Al atoms on the armchair and zigzag edge binding sites of monolayer graphene, and at the high-symmetry adsorption sites of single layer, bilayer, and trilayer graphene. All edge site binding energies were found to be substantially higher than the adsorption energies for all metals. The adatom migration activation barriers for the lowest energy migration paths on pristine monolayer, bilayer, and trilayer graphene were then calculated and found to be smaller than or within an order of magnitude of kBT at room temperature, implying very high mobility for all adatoms studied. This suggests that metal atoms evaporated onto graphene samples quickly migrate across the lattice and bind to the energetically favorable edge sites before being characterized in the microscope. We then prove this notion for Al and Au on graphene with scanning transmission electron microscopy (STEM) images showing that these atoms are observed exclusively at edge sites, and also hydrocarbon-contaminated regions, where the pristine regions of the lattice are completely devoid of adatoms. Additionally, we review the issue of fixing selected atomic positions during geometry optimization calculations for graphene/adatom systems and suggest a guiding principle for future studies

    Sustainable and Regenerable Alkali Metal-Containing Carbons Derived from Seaweed for CO2 Post-Combustion Capture

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    Alkali-based CO2 sorbents were prepared from a novel material (i.e., Laminaria hyperborea). The use of this feedstock, naturally containing alkali metals, enabled a simple, green and low-cost route to be pursued. In particular, raw macroalgae was pyrolyzed at 800 °C. The resulting biochar was activated with either CO2 or KOH. KOH–activated carbon (AC) had the largest surface area and attained the highest CO2 uptake at 35 °C and 1 bar. In contrast, despite much lower porosity, the seaweed-derived char and its CO2-activated counterpart outweighed the CO2 sorption performance of KOH–AC and commercial carbon under simulated post-combustion conditions (53 °C and 0.15 bar). This was ascribed to the greater basicity of char and CO2–AC due to the presence of alkali metal-based functionalities (i.e., MgO) within their structure. These were responsible for a sorption of CO2 at lower partial pressure and higher temperature. In particular, the CO2–AC exhibited fast sorption kinetics, facile regeneration and good durability over 10 working cycles. Results presented in the current article will be of help for enhancing the design of sustainable alkali metal-containing CO2 captors

    Long spin lifetime and large barrier polarisation in single electron transport through a CoFe nanoparticle

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    We have investigated single electron spin transport in individual single crystal bcc Co₃₀Fe₇₀ nanoparticles using scanning tunnelling microscopy with a standard tungsten tip. Particles were deposited using a gas-aggregation nanoparticle source and individually addressed as asymmetric double tunnel junctions with both a vacuum and a MgO tunnel barrier. Spectroscopy measurements on the particles show a Coulomb staircase that is correlated with the measured particle size. Field emission tunnelling effects are incorporated into standard single electron theory to model the data. This formalism allows spin-dependent parameters to be determined even though the tip is not spin-polarised. The barrier spin polarisation is very high, in excess of 84%. By variation of the resistance, several orders of magnitude of the system timescale are probed, enabling us to determine the spin relaxation time on the island. It is found to be close to 10 ÎŒs, a value much longer than previously reported

    Kinetically controlled fabrication of gold nanorods and investigation of their thermal stability via in-situ TEM heating

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    Size controlled CTAB-capped AuNRs with various aspect ratios (ARs) ranging from 1.63±0.13 to 4.12±0.25 were synthesized following a modified seed-mediated method. Their thermal stability was examined by in-situ TEM heating. The results revealed a structural change from rods to spheres with increasing temperature. At lower temperatures 600ÂșC, particles became increasingly spherical. This behaviour occurred at temperatures lower than the melting point of bulk gold supporting a surface diffusion mechanism with material diffusing from the tips and redepositing at the middle of the rods. The rate of change in AR appeared to increase for thinner AuNRs

    High‐resolution imaging of organic pharmaceutical crystals by transmission electron microscopy and scanning moirĂ© fringes

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    Formulation processing of organic crystalline compounds can have a significant effect on drug properties, such as dissolution rate or tablet strength/hardness. Transmission electron microscopy (TEM) has the potential to resolve the atomic lattice of these crystalline compounds and, for example, identify the defect density on a particular crystal face, provided that the sensitivity of these crystals to irradiation by high‐energy electrons can be overcome. Here, we acquire high‐resolution (HR) lattice images of the compound furosemide using two different methods: low‐dose HRTEM and bright‐field (BF) scanning TEM (STEM) scanning moirĂ© fringes (SMFs). Before acquiring HRTEM images of furosemide, a model system of crocidolite (asbestos) was used to determine the electron flux/fluence limits of low‐dose HR imaging for our scintillator‐based, complementary metal‐oxide semiconductor (CMOS) electron camera by testing a variety of electron flux and total electron fluence regimes. An electron flux of 10 e−/(Å2 s) and total fluence of 10 e−/Å2 was shown to provide sufficient contrast and signal‐to‐noise ratio to resolve 0.30 nm lattice spacings in crocidolite at 300 kV. These parameters were then used to image furosemide which has a critical electron fluence for damage of ≄10 e−/Å2 at 300 kV. The resulting HRTEM image of a furosemide crystal shows only a small portion of the total crystal exhibiting lattice fringes, likely due to irradiation damage during acquisition close to the compound's critical fluence. BF‐STEM SMF images of furosemide were acquired at a lower electron fluence (1.8 e−/Å2), while still indirectly resolving HR details of the (001) lattice. Several different SMFs were observed with minor variations in the size and angle, suggesting strain due to defects within the crystal. Overall BF‐STEM SMFs appear to be more useful than BF‐STEM or HRTEM (with a CMOS camera) for imaging the crystal lattice of very beam‐sensitive materials since a lower electron fluence is required to reveal the lattice. BF‐STEM SMFs may thus prove useful in improving the understanding of crystallization pathways in organic compounds, degradation in pharmaceutical formulations and the effect of defects on the dissolution rate of different crystal faces. Further work is, however, required to quantitatively determine properties such as the defect density or the amount of relative strain from a BF‐STEM SMF image

    Electron energy loss spectra from silica glass optical fibers

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    To investigate the possible structural differences between silica glass fibers and bulk silica glasses, electron energy loss spectroscopy (EELS) has been used to study the short-range and medium-range structures of both forms of silica glasses. The short-range structure of silica glass, such as the coordination and symmetry, was investigated by the energy loss near edge structure (ELNES) of Si L2,3-edges. The ordering structure in the medium-range was analyzed by the exponential optical absorption edge also known as the Urbach edge of the glasses. The optical absorption data were obtained from the low energy loss spectrum of EELS through Kramers-Kronig analysis. The results show that silica fiber has the same short-range structure as the bulk specimen, but is significantly more disordered than the bulk glasses

    A low-cost way to reduce greenhouse effects

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    Oak wood precursor was used for preparing low-cost CO2 sorbents. Adsorption is proposed as a cheaper alternative to chemical absorption, which is uneconomical, thus reducing the cost associated with the capture step. The raw material has been carbonised either by pyrolysis or by a hydrothermal carbonisation (HTC). Resulting biochars were then activated using CO2 . Initial chars and their activated counterparts were characterised by SEM imaging and N2 sorption measurements at 77 K. A significant rise in the BET surface area, total pore volume and micropore volume (textural parameters) occurred for all of the pristine chars after the activation process. Fast CO2 sorption kinetics (saturation reached in 3 mins.) and CO2 uptakes of up to ca. 6 wt. % have been measured by thermogravimetric analysis (TGA) at 35 ÂșC and 1 atm. The activated carbons (ACs) thus synthesised showed competitive performances compared to a commercial AC standard. Although the sorbents’ performances decreased at higher temperatures, they were easily regenerated after the capture stage

    Fabrication and Characterisation of an Adaptable Plasmonic Nanorod Array for Solar Energy Conversion

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    The surface plasmonic modes of a side-by-side aligned gold nanorod array supported on a gold substrate has been characterised by electron energy loss spectroscopy (EELS). Plasmonic coupling within the array splits the nanorods' longitudinal mode into a bright mode (symmetrically aligned dipoles) and a dark mode (anti-symmetrically aligned dipoles). We support this observation by means of finite element modelling (FEM)
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