Miniature Arcs for Synthesis of Carbon Nanotubes in Microgravity

Although many methods are available for producing single-walled carbon nanotubes (SWNTs), the conventional carbon arc process remains the most popular due to its simplicity and large production rate. In the carbon arc, SWNTs are catalytically synthesized by rapidly evaporating a graphite anode impregnated with NiN metal catalyst from which the nanotubes grow in an inert atmosphere. However, high temperatures inside the carbon arc generate strong buoyancy driven convection, and it is hypothesized that the non-uniform environment created by this flow has a large effect on the growth and morphology of the SWNTs. To study the effect of buoyancy on the arc process, a miniature carbon arc apparatus was developed to synthesize SWNTs in a microgravity environment substantially free from these strong convective flows. The reactor was operated for either 2.2 or 5 seconds during free-fall in the drop towers at the NASA Glenn Research Center. Two apparatus designs differing mainly in their production rate and power capacity were investigated. The first consisted of a miniaturized carbon arc employing a 1 mm diameter graphite anode and powered by a 0.54 F capacitor bank charged to 65 V. The second, larger apparatus employed a 4 mm diameter anode and was powered by a portable battery pack capable of providing in excess of 300 amps at 30 volts to the arc for the duration of a 5 second drop. Initial results indicated that transient heating is a very large effect in the short-duration drop tower carbon arcs, and thermal equilibrium of the arc plasma, buffer gas, and apparatus was not attained during the short microgravity periods. In addition, removal of the buoyant convection by the microgravity now allowed clear observation of large jets of evaporated carbon vapor streaming from the anode and mixing with the inert buffer gas. The initial mixing of these jets with the cold buffer gas combined with the thermal transient made it difficult to establish a uniform high temperature environment around the arc in the 2.1 to 5 second microgravity time interval, and even with a very high-powered arc, the arc region was cooler than in continuously operated arcs. Despite these difficulties, the miniature arc produced SWNTs in microgravity. However, given the large thermal transient to overcome, no dramatic difference in sample yield or composition was noted between normal gravity and q2-,andL%econd long microgravity runs

Dose and energy dependence of mechanical properties of focused electron beam induced pillar deposits from Cu(C5HF6O2)2

Bending and vibration tests performed inside the scanning electron microscope were used to mechanically characterize high-aspect pillars grown by focused electron-beam (FEB) induced deposition from the precursor Cu(C5HF6O2)2. Supported by finite element (FE) analysis the Young's modulus was determined from load-deflection measurements using cantilever-based force sensing and the material density from additional resonance vibration analysis. The pillar material consisted of a carbonaceous (C, O, F, H containing) matrix which embeds 5...10 at. % Cu deposited at 5 keV and 20 keV primary electron energy and 100 pA beam current, depending on primary electron energy. Young's moduli of the FEB deposits increased from 17+/-6 GPa to 25+/-8 GPa with increasing electron dose. The density of the carbonaceous matrix shows a dependence on the primary electron energy: 1.2+/-0.3 g cm-3 (5 keV) and 2.2+/-0.5 g cm-3 (20 keV). At a given primary energy a correlation with the irradiation dose is found. Quality factors determined from the phase relation at resonance of the fundamental pillar vibration mode were in the range of 150 to 600 and correlated to the deposited irradiation energy.Comment: 17 pages, 9 figures, 2 table

Structured activity and multiple group memberships as mechanisms of increased depression among young people not in employment, education or training

Aims Young people Not in Employment, Education and Training (NEET) are at increased risk of depression, yet mechanisms of this association are poorly understood. We hypothesised that being NEET has both behavioural and social identity consequences and that reductions in structured activity and multiple group memberships underlie increased depression in this group. Our purpose was to assess first whether depression was greater for NEET compared to non‐NEET young people from the same geographical locality, and secondly, whether a loss of structured activity leading to a reduction in multiple group memberships explains the NEET‐depression association. Methods The present study was a cross‐sectional between‐groups design using convenience sampling. Measures of depression, structured activity and multiple group memberships were obtained from 45 NEET young people and 190 university students (non‐NEET). Results The NEET group reported significantly more depression symptoms compared to the non‐NEET student control group. A path model specifying NEET status as a predictor of depression, with this association mediated by a reduction in structured activity and fewer multiple group memberships (standardised indirect = 0.03, unstandardised indirect = 0.62, P = 0.052, 95% bias corrected confidence intervals [0.21,1.44]), provided excellent fit to our data: χ2(3) = 0.26, P = 0.968, comparative fit index (CFI) = 1.00, root mean square error of approximation (RMSEA)<0.01, standardized root mean square residual (SRMR) = 0.01). Conclusions Our findings suggest that depression is elevated amongst NEET young people compared to non‐NEET students from the same locality. The association between NEET status and depression was partially mediated by reduced structured activity and its association with reduced multiple group memberships. Although using cross‐sectional data, our findings suggest social interventions may be a key resource in ameliorating depression amongst NEET young people; through preserving engagement in structured activity and the wellbeing benefits derived from arising multiple group memberships. Methods: The present study was a cross-sectional between-groups design using convenience sampling. Measures of depression, structured activity and multiple group memberships were obtained from 45 ‘NEET’ young people and 190 university students (Non-‘NEET’). Results: The NEET group reported significantly more depression symptoms compared to the Non-NEET student control group. A path model specifying NEET status as a predictor of depression, with this association mediated by a reduction in structured activity and fewer multiple group memberships (standardised indirect = 0.03, unstandardised indirect= 0.62, p= .052, 95% Bias Corrected CIs [0.21; 1.44]), provided excellent fit to our data χ2(3)= 0.26, p= .968, CFI= 1.00, RMSEA< .01, SRMR= .01, AIC= 2,792.75, BIC= 2,818.20). Conclusions: Our findings suggest depression is elevated amongst NEET young people compared to Non-NEET students from the same locality. The association between NEET status and depression was partially mediated by reduced structured activity and its association with reduced multiple group memberships. Although cross-sectional, our findings suggest social interventions may be a key resource in ameliorating depression amongst NEET young people; through preserving engagement in structured activity and the wellbeing benefits derived from arising multiple group memberships

The effectiveness of classroom vocabulary intervention for adolescents with language disorder

Purpose Phonological-semantic intervention has been shown to be effective in enhancing the vocabulary skills of children with language disorder in small-group or individual settings. Less is known about vocabulary interventions for adolescents with language disorder in whole-class models of delivery. The current study investigated the effectiveness of phonological-semantic vocabulary intervention for adolescents with language disorder, delivered by secondary school teachers within science lessons. Methods Seventy-eight adolescents with language disorder, aged 11 – 13 years, were taught science curriculum words by teachers in class, under two conditions: 1) 10 words taught through usual teaching practice; and 2) 10 matched words taught using an experimental intervention known as Word Discovery, which embedded phonological-semantic activities into the teaching of the syllabus. Ten similar control words received no intervention. Word knowledge was assessed pre-intervention, post-intervention, and follow-up. Results At pre-intervention, measures of depth of word knowledge and expressive word use did not differ between usual teaching practice and experimental words. At post-intervention, depth of knowledge of experimental words was significantly greater than that of usual teaching practice words. This significant advantage was not maintained at follow-up, although depth of knowledge for experimental words remained significantly higher at follow-up than at preintervention. At post-intervention, expressive use of experimental words was significantly greater than that of usual teaching practice words, and this significant difference was maintained at follow-up. There was no change in students’ depth of knowledge or expressive use of no-intervention words over time, confirming that the findings were not due to maturity or practice effects. Conclusion The experimental intervention was more effective than usual teaching practice in increasing the word knowledge of participants. Clinical and teaching implications include the importance of intervening during the adolescent years, with classroom vocabulary intervention being a viable option for collaborative teacher and speech and language therapy/pathology practice

Next Generation UAS Based Spectral Systems for Environmental Monitoring

This presentation provides information on the development of a small Unmanned Aerial System(UAS) with a low power, high performance Intelligent Payload Module (IPM) and a hyperspectral imager to enable intelligent gathering of science grade vegetation data over agricultural fields at about 150 ft. The IPM performs real time data processing over the image data and then enables the navigation system to move the UAS to locations where measurements are optimal for science. This is important because the small UAS typically has about 30 minutes of battery power and therefore over large agricultural fields, resource utilization efficiency is important. The key innovation is the shrinking of the IPM and the cross communication with the navigation software to allow the data processing to interact with desired way points while using Field Programmable Gate Arrays to enable high performance on large data volumes produced by the hyperspectral imager