ELECTROPHORETIC DEPOSITION OF B4C/AL CERMETS IN A 3D GEOMETRY WITH GREATER CURVATURE FOR APPLICATIONS IN ARMOR SYSTEMS

Armor technology in aircraft, vessels, vehicles, and personnel are improved by increasing performance, operational supportability, and survivability. Industrial production of armor is facilitated when coupled with a flexible and affordable manufacturing process (such as EPD). Ceramic/metal composite materials are attractive for armor applications for they combine the hardness of ceramics and the toughness of metals. Armor shaped by ceramic tiles and concave plates are in service. Yet ceramic armor is largely ‘flat’ when compared to the curvature required to provide additional protection of soldier extremities; or enable 3D geometries in air, land, and sea vehicle parts that are both functional and structural. Boron carbide is one of the lightest and hardest ceramics known. Introducing Al into the microstructure of boron carbide creates an ideal low porosity armor that is lightweight, hard, and tough. The conformal nature of the EPD process enables ceramic parts to be made that take the shape of the working electrode. High green body densities of EPD processed parts translate to less reduction in volume during sintering; thus enabling the formation of near net shaped B4C/Al cermet armor parts. These parts can then be incorporated into armor systems for increasing performance, operational supportability, and survivability of both service personnel and vehicles. We report the creation of B4C/Al cermets in simple 3D geometries produced by EPD to demonstrate how it can be used to make shaped parts of greater curvature for armor applications. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LL

Noninvasive Detection, Tracking, and Characterization of Aerogel Implants using Diagnostic Ultrasound

Medical implants are routinely tracked and monitored using different techniques, such as MRI, X‐ray, and ultrasound. Due to the need for ionizing radiation, the two former methods pose a significant risk to tissue. Ultrasound imaging, however, is non‐invasive and presents no known risk to human tissue. Aerogels are an emerging material with great potential in biomedical implants. While qualitative observation of ultrasound images by experts can already provide a lot of infor-mation about the implants and the surrounding structures, this paper describes the development and study of two simple B‐Mode image analysis techniques based on attenuation measurements and echogenicity comparisons, which can further enhance the study of the biological tissues and implants, especially of different types of biocompatible aerogels

Direct ink writing of ultra-high temperature ceramics

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Particle-Based Simulations of Electrophoretic Deposition with Adaptive Physics Models

This work represents an extension of mesoscale particle-based modeling of electrophoretic deposition (EPD), which has relied exclusively on pairwise interparticle interactions described by Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. With this standard treatment, particles continuously move and interact via excluded volume and electrostatic pair potentials under the influence of external fields throughout the EPD process. The physics imposed by DLVO theory may not be appropriate to describe all systems, considering the vast material, operational, and application space available to EPD. As such, we present three modifications to standard particle-based models, each rooted in the ability to dynamically change interparticle interactions as simulated deposition progresses. This approach allows simulations to capture charge transfer and/or irreversible adsorption based on tunable parameters. We evaluate and compare simulated deposits formed under new physical assumptions, demonstrating the range of systems that these adaptive physics models may capture.Comment: 34 pages, 10 figure

ELECTROPHORETIC DISPLAYS WITH TUNABLE, ANGLE-INDEPENDENT COLOR

Electrophoretic displays (EPDs), which exploit the surface charge of microparticles to control their deposition, have become widely available in consumer electronics, such as e-readers and smartwatches. However, a full-color EPD has yet to be demonstrated and commercialized. Here, we demonstrate colloidal assemblies of engineered quasi-amorphous photonic materials, using pigmentary α-Fe2O3/SiO2 core/shell nanoparticles, exhibiting non- iridescent tunable colors which can be tuned electrophoretically. The observed colors result from combination of colloidal particle arrangements, giving rise to structural color, along with the inherent pigmentary color of the α-Fe2O3/SiO2 nanoparticles. Colloidal particle assemblies of α-Fe2O3/SiO2 core/shell nanoparticles, and therefore the resulting colors, can be manipulated by shell thickness, particle concentration and external electrical stimuli. Dynamic tunability of α-Fe2O3/SiO2 nanomaterials in the visible wavelengths is demonstrated using reversible electrophoretic deposition with a noticeable difference between transmitted and reflected colors. The distinct contrast generated can be exploited for tunable display applications. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-704082

In-situ USAXS/SAXS Investigation of Tunable Structural Color in Amorphous Photonic Crystals during Electrophoretic Deposition

Amorphous photonic crystals (APCs) formed via electrophoretic deposition (EPD) exhibit non-iridescent, angle-independent, structural colors believed to arise from changes in the particle-particle interactions and inter-particle spacing, representing a potential new paradigm for display technologies. However, inter-particle dynamics on nanometer length scales that govern (and enable control over) the displayed color, crystallinity, and other characteristics of the photonic structures, are not well understood. Unfortunately, typical lab-based characterization techniques such as SEM, TEM, and Computed Tomography (CT) are generally performed ex-situ once the sample deposit has been dried. In this work, in-situ USAXS/SAXS/WAXS studies of three-dimensional colloidal particle arrays (of varying particle size and concentration) were performed in order to identify their structural response to applied external electric fields. This data was compared to simultaneously acquired UV-Vis spectra to tie the overall electrically induced structure of the APCs directly to the observed changes in visible color. The structural evolution of the APCs provides new information regarding the correlation between nano-scale particle-particle interactions and the corresponding optical response. To our knowledge, there has been no other prior studies examining the structure of APCs during the application of an electric field. This novel, in-situ USAXS study has helped to gain a better fundamental understanding of how the properties of APCs can be controlled for the advancement of optical displays. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-725437-DRAF

We are playing football: Seeing the game on Panapompom, PNG

© Royal Anthropological Institute 2011.This article is about football, played by men from Panapompom in Papua New Guinea's Milne Bay province. Football is problematic not because it is culturally appropriated or modified, but rather because Panapompom desired accurately to reproduce the appearance of the international game. As such it questions conventional frames of reference. An interpretation in terms of culture obscures Panapompom interests in football: its globally recognizable character. It mattered profoundly that Panapompom people played football. Yet framing football as a universal sporting institution is equally inadequate, erasing the specific political project that was embedded in the game. Displacing the interpretative framings, I argue that football itself provides a context in which Panapompom people can judge themselves in relation to others, who are defined in terms of colonial and postcolonial discourses on ‘development’. Taking football as a contextualizing image, Panapompom people appear in distinctive ways in the field of relationships that it defines.ESR

Social media for health promotion and weight management: A critical debate

© 2018 The Author(s). Background: In 2016 an estimated 1.9 billion adults world-wide were either overweight or obese. The health consequences of obesity are responsible for 2.8 million preventable deaths per year. The WHO now considers obesity as a global epidemic and recommends population-wide health promotion strategies to address this issue. Weight gain is caused by increased energy intake and physical inactivity, so treatment should focus on changes to behaviour regarding diet and physical activity. Discussion: The WHO has also recognised the importance of social resources as a valuable agent for behaviour change in health promotion. Social resources are translated at the community level as support provided by significant others such as family, partners and peers, in the form of information, material aid and encouragement. Social support has been shown to improve health and well-being, whereas social isolation has been shown to have a negative impact on health outcomes. Social support provided by peers has been shown to be a useful strategy to employ in weight management programmes. The documented increased use of ICT and social media has presented health promoters with a potentially useful medium to increase social support for weight management. Conclusion: While the use of social media for health promotion is an emerging field of investigation, preliminary research suggests that it increases participant engagement, and may provide a cost-effective tool to provide social support for individuals participating in weight management programmes. With stringent privacy protocols in place, social media may be a useful, cost-effective accompaniment to multifactorial weight management programmes. However more research is needed to identify how to make the best use of social media as health promotion tool