Polymer Matrix Nanocomposites by Inkjet Printing

This paper describes work on a continuing project to form functional composites that contain ceramic nanoparticles using a Solid Freeform Fabrication (SFF) inkjet printing method. The process involves inkjet deposition of monomer/particle suspensions in layers followed by curing each layer in sequence using UV radiation. The reactive monomer is hexanediol-diacrylate (HDODA); the polymer forming reaction proceeds by a free radical mechanism. The liquid monomer containing nanoparticles is essentially a printing ink formulation. Successfully suspending the particles in the monomer is critical. We have developed a surface treatment method for forming stable suspensions of the nanoparticles so that they remain discrete throughout the processing sequence. The SFF process involves careful control of the polymer cure so that the interface between layers is seamless and residual stresses in the composites are eliminated. An immediate use for such composites is in optical applications as gradient refractive index lenses (GRIN). GRIN lenses have planar surfaces, eliminating the need for costly grinding and polishing. The planar surfaces also eliminate optical aberrations that result at the edges of spherical lenses and diminish the accuracy of focus. If the appropriate nanoparticles are fully dispersed they will modify the polymer's refractive index without interfering with light transmission. The effect is additive with volume concentration. Using 'inks' of different compositions in a multiple nozzle inkjet printer allows the formation of composites with precise composition gradients. Since an object is built one planar layer at a time, changes can be made readily both within each layer and from layer to layer. Inkjet printing with picoliter resolution is ideal for this task. Working with SiC nanoparticles in HDODA as a model system for demonstrating the inkjet deposition process, nanocomposite films with a linear concentration gradient varying from 0 to 4.5% (wt) were fabricated on Silicon wafers. These composites are 30 layer films, which total 140µm in thickness. Each layer in the composite is about 5 µm in thickness. Analytical methods for characterizing the dispersion of the nanoparticles in the composite and some of the salient optical properties of the composites also were established. The status of the program is reviewed in this paper.Mechanical Engineerin

Stem diameter growth rates in a fire-prone savanna correlate with photosynthetic rate and branch-scale biomass allocation, but not specific leaf area

Plant growth rates strongly determine ecosystem productivity and are a central element of plant ecological strategies. For laboratory and glasshouse‐grown seedlings, specific leaf area (SLA; ratio of leaf area to mass) is a key driver of interspecific variation in growth rate (GR). Consequently, SLA is often assumed to drive GR variation in field‐grown adult plants. However, there is an increasing evidence that this is not the general case. This suggests that GR – SLA relationships (and perhaps those for other traits) may vary depending on the age or size of the plants being studied. Here we investigated GR – trait relationships and their size dependence among 17 woody species from an open‐canopy, fire‐prone savanna in northern Australia. We tested the predictions that SLA and stem diameter growth rate would be positively correlated in saplings but unrelated in adults while, in both age classes, faster‐GR species would have higher light‐saturated photosynthetic rate (Asat), higher leaf nutrient concentrations, higher branch‐scale biomass allocation to leaf versus stem tissues and lower wood density (WD). SLA showed no relationship to stem diameter GR, even in saplings, and the same was true of leaf N and P concentrations, and WD. However, branch‐scale leaf:stem allocation was strongly related to GR in both age groups, as was Asat. Together, these two traits accounted for up to 80% of interspecific variation in adult GR, and 41% of sapling GR. Asat is rarely measured in field‐based GR studies, and this is the first report of branch‐scale leaf:stem allocation (analogous to a benefit:cost ratio) in relation to plant growth rate. Our results suggest that we may yet find general trait‐drivers of field growth rates, but SLA will not be one

Heart rate, energy expenditure, and affective responses from children participating in trampoline park sessions compared with traditional extra-curricular sports clubs

BACKGROUND: Lack of physical activity (PA) is becoming an issue in younger populations. Trampoline parks are newly popular environments for PA yet research on their use is scarce. Thus the present study compared heart rate, energy expenditure, and affective responses in children participating in trampoline park sessions compared with extracurricular sports clubs. METHODS: Children (aged 6-11 years; N.=16 females, N.=10 males) participated in 3 trampoline park sessions and 3 extracurricular sports club sessions lasting ~45 minutes over 3 weeks. Heart rate, energy expenditure, and affective responses through the circumplex model, were measured. RESULTS: Both conditions elicited moderate-vigorous PA. Average heart rate (mean difference [95%CIs]=27.6 fc [23.5 to 31.8]), peak heart rate (mean difference [95%CIs]=24.2 fc [20.8 to 27.6]) and energy expenditure (mean difference [95%CIs]=3.2 kcals.min-1 [2.7 to 3.6]) were all significantly higher for the trampoline sessions. Affective responses for both conditions elicited feelings of “excitement.” CONCLUSIONS: Both extracurricular sports clubs and trampoline park activities provide moderate-vigorous PA, though the latter may result in higher heart rate and energy expenditure responses. Both however produce similar positive affective responses. As such, both could be valuable options for PA opportunities for children

Physical activity, mental and personal well-being, social isolation, and perceptions of academic attainment and employability in university students: The Scottish and British active students surveys

Background: Physical activity (PA) promotes health and well-being. For students, university represents a transitional period, including increased independence over lifestyle behaviors, in addition to new stressors and barriers to engaging in PA. It is, therefore, important to monitor PA trends in students to gain a greater understanding about the role it might play in physical and mental well-being, as well as other factors, such as attainment and employability.  Methods: Cross-sectional surveys were conducted in 2016 in Scottish universities and colleges, and in 2017 in universities and colleges across the United Kingdom, and the data were pooled for the present study (N = 11,650). Cumulative ordinal logistic regression was used to model the association between PA levels and mental and personal well-being, social isolation, and perceptions of academic attainment and employability.  Results: Only 51% of the respondents met the recommended levels of moderate to vigorous PA per week. There was a linear relationship between PA levels and all outcomes, with better scores in more active students.  Conclusions: UK university students are insufficiently active compared with the general population of 16- to 24-year olds. Yet, students with higher PA report better outcomes for mental and personal well-being, social isolation, and perceptions of academic attainment and employability

Global Assessment of the SMAP Level-4 Surface and Root-Zone Soil Moisture Product Using Assimilation Diagnostics

The Soil Moisture Active Passive (SMAP) mission Level-4 Soil Moisture (L4_SM) product provides 3-hourly, 9-km resolution, global estimates of surface (0-5 cm) and root-zone (0-100 cm) soil moisture and related land surface variables from 31 March 2015 to present with ~2.5-day latency. The ensemble-based L4_SM algorithm assimilates SMAP brightness temperature (Tb) observations into the Catchment land surface model. This study describes the spatially distributed L4_SM analysis and assesses the observation-minus-forecast (O-F) Tb residuals and the soil moisture and temperature analysis increments. Owing to the climatological rescaling of the Tb observations prior to assimilation, the analysis is essentially unbiased, with global mean values of ~0.37 K for the O-F Tb residuals and practically zero for the soil moisture and temperature increments. There are, however, modest regional (absolute) biases in the O-F residuals (under ~3 K), the soil moisture increments (under ~0.01 cu.m/cu.m), and the surface soil temperature increments (under ~1 K). Typical instantaneous values are ~6 K for O-F residuals, ~0.01 (~0.003) cu.m/cu.m for surface (root-zone) soil moisture increments, and ~0.6 K for surface soil temperature increments. The O-F diagnostics indicate that the actual errors in the system are overestimated in deserts and densely vegetated regions and underestimated in agricultural regions and transition zones between dry and wet climates. The O-F auto-correlations suggest that the SMAP observations are used efficiently in western North America, the Sahel, and Australia, but not in many forested regions and the high northern latitudes. A case study in Australia demonstrates that assimilating SMAP observations successfully corrects short-term errors in the L4_SM rainfall forcing

Moving at scale: Promising practice and practical guidance on evaluation of physical activity programmes in the UK

Paper presented at the 7th International Society for Physical Activity and Health Congress, 15th-17th October 2018, London, England.Purpose: To develop effective physical activity (PA) frameworks policy makers require an understanding of which interventions increase PA at population level. This investigation identified PA interventions in the UK; considered key challenges in evaluating interventions; and provided guidance to inform and support effective evaluation. It followed from a 2014 investigation that identified and benchmarked PA interventions in England. Methods: An open call for examples of good and promising practice was made to organisations, groups, and individuals delivering PA interventions in the UK. Participants completed a questionnaire based upon elements of the Standard Evaluation Framework for Physical Activity Programmes. Nesta Standards of Evidence were interpreted and used to score projects and programmes based on an assessment of the evaluation method used. Results: A total of 302 completed submissions were assessed; 17 interventions used a control or comparison group; 12 were evaluated by an external evaluator; 55% of interventions collected pre/post measures; 22% engaged between 1,000 and 5,000 participants with 8% including >25,000 participants; 27% had been on-going for 2-5 years; 55% were delivered in a local authority leisure facility; 40% received funding from local authorities and 32% from private funders. Conclusions: The quality of monitoring, data collection, and evaluation processes embedded into programme delivery has improved since the 2014 review, which is encouraging. Non-inclusion of control or comparison groups (although not always appropriate) remains a barrier in demonstrating the causal impact of programmes. Few studies reported independent evaluation. Inadequate or incomplete submissions also impacted assessment.Published versio