Properties of model E-glass fiber composites with varying matrix monomer ratios

ObjectiveTo evaluate properties of fiber-reinforced-composites (FRC) containing Bis-EMA/UDMA monomers but identical dispersed phase (60% wt BaSi glass power +10% wt E-glass fibre).MethodsA control (Group A), monomer mixture comprising 60% Bis-GMA, 30% TEGDMA, and 10% PMMA (typical FRC monomers) was used. The following monomer mass fractions were mixed: 50% bis-GMA plus 50% of different ratios of Bis-EMA+UDMA to produce consistent formulations (Groups B-E) of workable viscosities was also studied. Flexural strength (FS), fracture toughness (KIC), water sorption (SP), solubility (SL) and hygroscopic expansion (HE) were measured. FS and KIC specimens were stored for 1, 7 d, and 30 d in water at 37 °C. SP/SL specimens were water-immersed for 168d, weighed at intervals, then dried for 84 d at 37 °C. To analyze differences in FS, and KIC, a two-way ANOVA and Tukey post-hoc tests (α = 0.05) were conducted. For SP/SL, and HE, one-way ANOVA with subsequent Tukey post-hoc tests (α = 0.05) were utilized.ResultsFS and KIC for groups A, D, E decreased progressively after 1 d. Groups B and C (highest amounts of Bis-EMA) did not decrease significantly. The modified matrix composites performed significantly better than the control group for SP and HE. The control group outperformed the experimental composites only for SL with up to 250% higher SL for group E (6.9 μg/mm) but still below the maximum permissible threshold of 7.5 μg/mm. Significance:Experimentalcomposites with highest amounts of Bis-EMA showed improved hydrolytic stability and overall enhancement in several clinically-relevant properties. This makes them potential candidates for alternative matrices to a semi-interpenetrating network in fiber-reinforced composites

Spatio-temporal influence of tundra snow properties on Ku-band (17.2 GHz) backscatter

During the 2010/11 boreal winter, a distributed set of backscatter measurements was collected using a ground-based Ku-band (17.2 GHz) scatterometer system at 26 open tundra sites. A standard snow-sampling procedure was completed after each scan to evaluate local variability in snow layering, depth, density and water equivalent (SWE) within the scatterometer field of view. The shallow depths and large basal depth hoar encountered presented an opportunity to evaluate backscatter under a set of previously untested conditions. Strong Ku-band response was found with increasing snow depth and snow water equivalent (SWE). In particular, co-polarized vertical backscatter increased by 0.82 dB for every 1 cm increase in SWE (R2 = 0.62). While the result indicated strong potential for Ku-band retrieval of shallow snow properties, it did not characterize the influence of sub-scan variability. An enhanced snow-sampling procedure was introduced to generate detailed characterizations of stratigraphy within the scatterometer field of view using near-infrared photography along the length of a 5m trench. Changes in snow properties along the trench were used to discuss variations in the collocated backscatter response. A pair of contrasting observation sites was used to highlight uncertainties in backscatter response related to short length scale spatial variability in the observed tundra environment

Modelling Enterprise for a Disability Charity

Work can allow people to express themselves and develop skills and abilities, create social bonds, and receive appreciation both symbolic and economic but what if you cannot access employment? How can the principles of enterprise be applied to create opportunities for greater self-development and social inclusion for people with a spectrum of impairments that currently utilise day services? This research focuses on defining a model of enterprise for the Percy Hedley Foundation. Using a mixed-method approach, case study and co-creative design-led innovation practice, the research reviews sector exemplars and produced propositional materials for critique and debate. Through synthesis and evaluation the research presents a model of enterprise that explores the flexibility of the concept ‘meaningful employment’. The research aims to contribute to understanding about how disability support organisations can shift from a model of social care to a model of endeavour in order to increase social impact on investment. The paper suggests organisational conditions to enable people with a range of impairments to meaningfully engage in enterprise activity and be enterprising

Derivation and evaluation of a new extinction coefficient for use with the n-HUT snow emission model

In this study, snow slab data collected from the Arctic Snow Microstructure Experiment were used in conjunction with a six-directional flux coefficient model to calculate individual slab absorption and scattering coefficients. These coefficients formed the basis for a new semiempirical extinction coefficient model, using both frequency and optical diameter as input parameters, along with the complex dielectric constant of snow. Radiometric observations, at 18.7, 21.0, and 36.5 GHz at both horizontal polarization (H-Pol) and vertical polarization (V-Pol), and snowpit data collected as part of the Sodankylä Radiometer Experiment were used to compare and contrast the simulated brightness temperatures produced by the multi-layer Helsinki University of Technology snow emission model, utilizing both the original empirical model and the new semiempirical extinction coefficient model described here. The results show that the V-Pol RMSE and bias values decreased when using the semiempirical extinction coefficient; however, the H-Pol RMSE and bias values increased on two of the lower microwave bands tested. The unbiased RMSE was shown to decrease across all frequencies and polarizations when using the semiempirical extinction coefficient

A retrospective analysis of ketamine administration by Critical Care Paramedics in a pre-hospital care setting

This document is the Accepted Manuscript version of the following article: Alan Cowley, Julia Williams, Pete Westhead, Nick Gray, Adam Watts, and Fionna Moore, ‘A retrospective analysis of ketamine administration by critical care paramedics in a pre-hospital care setting’, British Paramedic Journal, Vol. 2 (4): 25-31, January 2018. Under embargo until 1 January 2019. The final, definitive version is available online via: https://doi.org/10.29045/14784726.2018.03.2.4.25ABSTRACT  Objective: This project aims to describe pre-hospital use of Ketamine in trauma by South East Coast Ambulance Service Critical Care Paramedics and evaluate the occurrence of any side effects or adverse events.  Methods: A retrospective analysis of patients receiving pre-hospital ketamine for trauma between 16th March 2013 and 30th April 2017. Administrations were identified from Advanced Life Saving Intervention and Procedure reports submitted by the clinician and, later, from an electronic database. Each was scrutinised for patient demographics, indication, doses and reports of side effects or adverse events.  Results: A total of 510 administrations were identified. Thirty-four of these were excluded due to a lack of completeness, ketamine being drawn and not administered or the administering clinician not being a Critical Care Paramedic. A further twenty-seven were excluded due to being given for a non-traumatic reason. Of the remaining 449 administrations, males accounted for 302 (67.3%) compared to 147 (32.7%) females. The average age was 45.26 with women older (53.2 years vs. 41.4 years). The mean dose was 32.63mg (IQR 20; 5-180mg). Isolated lower limb trauma was the most common indication (228/449; 50.8%). Notable side effects were reported on 15 occasions with one adverse event. The mean dose for side effect was 29.3mg. Males received a higher dose when exhibiting a side effect (31.90mg vs. 26.43mg).  Conclusions: Critical Care Paramedics within a well governed system are able to safely administer ketamine within an approved dosing regimen under a Patient Group Direction. Mean doses are in keeping with nationally approved guidelines. The demographics represent the national trauma statistics. Reported side effects were within the described frequencies in the British National Formulary, and reported in other studies. Numbers Needed to Harm (NNH) also appear acceptable given that the side effects are easy to manage within a Critical Care Paramedic’s scope of practice. However, the project has significant limitations and so further, prospective research is required. Peer reviewe

Tracking infectious diseases in a warming world.

Using infectious diseases sensitive to climate as indicators of climate change helps stimulate andinform public health response