291 research outputs found

    Metal-catalyst-free growth of silica nanowires and carbon nanotubes using Ge nanostructures

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    The use of Ge nanostructures is investigated for the metal-catalyst-free growth of silica nanowires and carbon nanotubes (CNTs). Silica nanowires with diameters of 10-50 nm and lengths of ? 1 ?m were grown from SiGe islands, Ge dots, and Ge nanoparticles. High-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS) reveal that the nanowires grow from oxide nanoparticles on the sample surface. We propose that the growth mechanism is thermal diffusion of oxide through the GeO2 nanostructures. CNTs with diameters 0.6-2.5 nm and lengths of less than a few ?m were similarly grown by chemical vapor deposition from different types of Ge nanostructures. Raman measurements show the presence of radial breathing mode peaks and the absence of the disorder induced D-band, indicating single walled CNTs with a low defect density. HRTEM images reveal that the CNTs also grow from oxide nanoparticles, comprising a mixture of GeO2 and SiO2

    Growth of Carbon Nanotubes on HfO2 towards Highly Sensitive Nano-Sensors

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    Carbon nanotube (CNT) growth on HfO2 is reported for the first time. The process uses a combination of Ge and Fe nanoparticles and achieves an increase in CNT density from 0.15 to 6.2 mm length/mm2 compared with Fe nanoparticles alone. The synthesized CNTs are assessed by the fabrication of back-gate CNT field-effect transistors with Al source/drain contacts for nano-sensor applications. The devices exhibit excellent p-type behavior with an Ion=Ioff ratio of 105 and a steep sub-threshold slope of 130 mV/dec

    Metal-catalyst-free growth of carbon nanotubes and their application in field-effect transistors

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    The metal-catalyst-free growth of carbon nanotubes (CNTs) using chemical vapor deposition and the application in field-effect transistors (FETs) is demonstrated. The CNT growth process used a 3-nm-thick Ge layer on SiO2 that was subsequently annealed to produce Ge nanoparticles. Raman measurements show the presence of radial breathing mode peaks and the absence of the disorder induced D-band, indicating single walled CNTs with a low defect density. The synthesized CNTs are used to fabricate CNTFETs and the best device has a state-of-the-art on/off current ratio of 3×108 and a steep sub-threshold slope of 110 mV/dec

    The use of history to identify anterior cruciate ligament injuries in the acute trauma setting: the 'LIMP index'

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    YesObjective To identify the injury history features reported by patients with ACL injuries and determine whether history may be used to identify patients requiring follow-up appointments from acute trauma services. Multi-site cross-sectional service evaluation using a survey questionnaire design conducted in the UK. The four injury history features investigated (LIMP) were ‘Leg giving way at the time of injury’, ‘Inability to continue activity immediately following injury’, ‘Marked effusion’ and ‘Pop (heard or felt) at the time of injury’. 194 patients with ACL injury were identified of which 165 (85.5%) attended an acute trauma service. Data on delay was available for 163 (98.8%) of these patients of which 120 (73.6%) had a follow-up appointment arranged. Patients who had a follow-up appointment arranged waited significantly less time for a correct diagnosis (geometric mean 29 vs 198 days; p<0.001) and to see a specialist consultant (geometric mean 61 vs 328 days; p<0.001). Using a referral threshold of any 2 of the 4 LIMP injury history features investigated, 95.8% of patients would have had a follow-up appointment arranged. Findings support the value of questioning patients on specific injury history features in identifying patients who may have suffered ACL injury. Using a threshold of 2 or more of the 4 LIMP history features investigated would have reduced the percentage of patients inappropriately discharged by 22.2%. Evidence presented suggests that this would significantly reduce the time to diagnosis and specialist consultation minimising the chance of secondary complications

    Learners' experience and perceived impact of a health literacy program in adult basic education: a qualitative study.

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    Objectives and importance of the study: Adult literacy programs aim to empower learners to participate more effectively in everyday life. This includes programs with health content embedded in curricula to target health literacy. Adult learners who attend these programs represent a heterogeneous population, but include a high proportion of hard-to-reach or socially disadvantaged groups in terms of age, ethnicity, educational background, language and prevalence of learning disabilities. In 2014, we conducted a cluster-randomised controlled trial of a health literacy program in adult basic education classes across New South Wales, Australia. This paper reports findings from a qualitative study exploring learners' experience of the course and its perceived impact on their lives, as well as their understanding and confidence about health. STUDY TYPE:Qualitative interview study. METHOD:We conducted semistructured interviews as part of the evaluation of the 18-week health literacy program, with participants purposively recruited from six health literacy classes (n = 22). Researchers trained in qualitative methods interviewed adult learners either face to face or over the phone using a topic guide. Data was analysed using the Framework method, a matrix-based approach to thematic analysis. RESULTS:The majority of interviewees were female, lived in metropolitan areas and were from non-English-speaking backgrounds. Most had existing self-reported health problems and inadequate functional health literacy. Most participants described positive impacts of the health literacy course on their language, literacy and numeracy skills, functional health literacy skills, and health knowledge. They also reported being able to translate this into health actions including interacting with providers, accessing and using healthcare, and managing health and illness (e.g. making healthier food choices). Learners also described positive social outcomes of the course, including feelings of connectedness and interpersonal trust within a new network of learners, and reported sharing new knowledge with others in their communities. CONCLUSIONS:The findings add value to existing limited evidence that has demonstrated the untapped potential of adult basic education to develop health literacy skills among socially disadvantaged groups. Learners valued the opportunity to share experiences in structured group learning, and reported confidence to transfer new knowledge into their home and wider social network

    Teacher and youth priorities for education for environmental sustainability: A co-created manifesto

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    What would it mean to put environmental sustainability at the heart of education? This article describes a process of inclusive, participatory manifesto-making to identify young people's (aged 16–18 years) and teachers' priorities for education for environmental sustainability across the UK. Drawing on analysis of qualitative data from over 200 teachers and young people who participated in futures and visualisation workshops, we identify key educational priorities at the levels of classroom, school, community and policy, based on consensus between teacher and youth perspectives. Whilst consensus-seeking comes with a risk of favouring ‘soft’ actions which reinforce unsustainable practices and systems, the process of identifying more desirable futures and immediate barriers that must be negotiated to reach them has the potential to create spaces for more critical pedagogies and practices. There is a need for policy makers and school leaders to recognise the interests of teachers and young people to enable greater participation in decision making at different scales, and to ensure that those with the greatest capacity bear their burden of responsibility for education for environmental sustainability

    Genetic Traces of Recent Long-Distance Dispersal in a Predominantly Self-Recruiting Coral

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    Understanding of the magnitude and direction of the exchange of individuals among geographically separated subpopulations that comprise a metapopulation (connectivity) can lead to an improved ability to forecast how fast coral reef organisms are likely to recover from disturbance events that cause extensive mortality. Reef corals that brood their larvae internally and release mature larvae are believed to show little exchange of larvae over ecological times scales and are therefore expected to recover extremely slowly from large-scale perturbations.Using analysis of ten DNA microsatellite loci, we show that although Great Barrier Reef (GBR) populations of the brooding coral, Seriatopora hystrix, are mostly self-seeded and some populations are highly isolated, a considerable amount of sexual larvae (up to approximately 4%) has been exchanged among several reefs 10 s to 100 s km apart over the past few generations. Our results further indicate that S. hystrix is capable of producing asexual propagules with similar long-distance dispersal abilities (approximately 1.4% of the sampled colonies had a multilocus genotype that also occurred at another sampling location), which may aid in recovery from environmental disturbances.Patterns of connectivity in this and probably other GBR corals are complex and need to be resolved in greater detail through genetic characterisation of different cohorts and linkage of genetic data with fine-scale hydrodynamic models
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