674 research outputs found

    HRXRD study of the theoretical densities of novel reactive sintered boride candidate neutron shielding materials

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    Reactive Sintered Borides (RSBs) are novel borocarbide materials derived from FeCr-based cemented tungsten (FeCr-cWCs) show considerable promise as compact radiation armour for proposed spherical tokamak,[1],[2],[3],[4],[5]. Six candidate compositions (four RSBs, two cWCs) were evaluated by high-resolution X-ray diffraction (XRD), inductively coupled plasma (ICP), energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) to determine the atomic composition, phase presence, and theoretical density. RSB compositions were evaluated with initial boron contents equivalent to 25 at% 30 at%. All RSB compositions showed delamination and carbon enrichment in the bulk relative to the surface, consistent with non-optimal binder removal and insufficient sintering time. Phase abundance within RSBs derived from powder XRD was dominated by iron tungsten borides (FeWB/FeW2B2), tungsten borides (W2B5/WB) and iron borides. The most optimal RSB composition (B5T522W) with respect to physical properties and highest ρ/ρtheo had ρtheo = 12.59 ± 0.01 g cm-3 for ρ/ρtheo = 99.3% and had the weigh-in and post-sintered W : B : Fe abundance closest to 1 : 1 : 1. This work indicates that despite their novelty, RSB materials can be optimized and in principle be processed using existing cWC processing routes

    Proton and gamma irradiation of novel tungsten boride and carbide candidate shielding materials

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    Low-activation cWC and RSBs show considerable promise as broad-spectrum radiation-dense materials suitable for use in compact spherical tokamaks (cSTs). The radiation response of novel radiation dense materials cemented tungsten carbide (cWC) and reactive sintered borides (RSBs) at ambient and non-ambient temperatures is investigated for the first time in this work. Sample irradiation consisted of 1.5 MeV protons at 408 K and at 873 K and 60Co gamma irradiation at 293 K and 77 K. Evaluation of radiation-induced damage via electron backscatter diffraction (EBSD) and TEM observed that cWCs have greater radiation attenuation than RSBs but RSBs have more diffuse dislocation distributions. Temperature at irradiation was observed to have a significant impact on dislocation presence with more diffuse dislocation presence in RSBs at 873K but with a well-defined damage front in cWCs as determined by changes in band contrast and indexing in EBSD and by dislocation presence in TEM. Dislocation presence observed to be significantly phase-dependant, particularly for cWC where the WC phase acts to absorb the bulk of radiation-induced dislocations. Both cWC and RSBs demonstrated significant γ-ray attenuation at 77 K with most radiation-induced changes confined to the top 25 µm from the incident face

    Thermophysical properties of Co-free WC-FeCr hardmetals

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    Fe-Cr alloys can potentially replace carcinogenic Co as the binder system in WC-hardmetals. Furthermore, they may be used in emerging applications such as nuclear fusion reactor shielding, where use of Co is forbidden due to the formation of hazardous activated species. In such applications, a good understanding of thermophysical properties is critical to predicting high temperature performance. By combining several thermal analysis techniques (dilatometry, laser flash and calorimetry) we have determined the thermal conductivity and thermal expansivity of several grades of WC-FeCr hardmetals between room temperature and 1200 °C. In these materials the WC grain size was varied between 0.2 and 5 microns. The binder content was kept constant at 10 wt.%, and the nominal binder composition was Fe-8 wt.% Cr. The room temperature thermal conductivities of these materials varied between about 50 and 110 W/m-K, which are similar values to analogous WC-Co materials. Thermal expansion curves exhibited discontinuous shrinkage events at about 850 °C, due to an allotropic phase transition within the FeCr binder between its BCC and FCC structures. The magnitude of the shrinkage was about a third that predicted by the rule-of-mixtures, suggesting significant internal stresses could be generated during the transformation. Such internal stresses could affect the properties of WC-FeCr hardmetals when operating at high temperature

    Non-ambient X-ray and neutron diffraction of novel relaxor ferroelectric x(Bi2(Zn2/3, Nb1/3)O7 – (1-x)BaTiO3 (BZN-BT)

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    The first determination of the phase diagram of the novel ferroelectric relaxor xBi(Zn2/3 Nb1/3)O3-BaTiO3 (BZN-BT) with combined high resolution X-ray and neutron up to the miscibility limit near x(BZN) = 20.0% over a temperature range 20 K < T < 400 K. Combined X-ray and neutron data shows instability within the xBZN-(1-x)BT system reaches a maximum at x = 3.9% and is driven by B-site displacement and distortion of the oxygen octahedra in the polar phases Composition-dependant effects include a narrow Amm2-dominated region focused at x = 3.9%, significant convergence of the lattice parameters in both P4mm and Amm2 phases and a sharp maxima in d33 and Psat. Lattice parameter dilation at x ≥ 4.0% was observed for both P4mm and Amm2 unit cells, alongside the first appearance of Pm-3m at 295 K and the onset of significant dielectric relaxation. Low-temperature neutron diffraction indicated a weak or absent temperature dependence on the transition between ferroelectric at x = 3.9% to ferroelectric relaxor at x = 4.0%. Temperature-dependant phase transitions were eliminated near x = 3.0%, with the ferroelectric limit observed at x = 5.0% and transition to a low-loss relaxor dielectric near x = 8.0%

    What motivates community mental and behavioral health organizations to participate in LGBTQ+ cultural competency trainings?

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    LGBTQ+ populations show elevated rates of poor mental health and substance use relative to their heterosexual and cisgender counterparts but often experience stigma and marginalization when seeking mental health care. Mental and behavioral health organizations and therapists recognize a need for LGBTQ+ cultural competency training opportunities and are interested in participating in these trainings. Professional organizations and state licensing bodies should consider policies that require accredited graduate programs and continuing education opportunities to include LGBTQ+ training and competencies.The constantly evolving language, understanding, and cultural context regarding the mental health of lesbian, gay, bisexual, transgender, queer, and other sexual and gender diverse individuals (LGBTQ+) require mental health providers to obtain LGBTQ+ cultural competency training to be affirmative and effective with this population. Unfortunately, many providers are not obtaining this ongoing training and mental health disparities continue to plague LGBTQ+ populations. Guided by the Consolidation Framework for Implementation Research (CFIR), we conducted eight focus groups with community mental and behavioral health organization (MBHO) administrators (e.g., directors, clinical supervisors) and therapists to explore what factors facilitated or inhibited their adoption and implementation of a multicomponent LGBTQ+ cultural competency training program that required administrator and therapist participation in multiple learning sessions over several months (i.e., workshop, clinical consultation, and organizational technical assistance). Results from template analysis supported CFIR-aligned themes, including characteristics of individuals, inner setting, outer setting, and process, and two additional codes—marketing and other/previous training opportunities—emerged from the focus group data. Findings suggest that therapists are motivated to engage in such a program because they want to feel more efficacious, and administrators see the benefits of LGBTQ+ training programs for their clientele and marketing. Barriers to adoption and implementation include cost and personnel resistance, although participants believed these barriers were surmountable. Emphasizing therapist efficacy, clientele need, and benefits for marketing mental and behavioral health services could motivate MBHOs’ and therapists’ adoption and implementation of LGBTQ+ cultural competency training.This work was supported by the University of Maryland Prevention Research Center cooperative agreement no. U48DP006382 from the Centers for Disease Control and Prevention (CDC). Any interpretations and opinions expressed herein are solely those of the authors and may not reflect those of the CDC

    Coral restoration effectiveness: multiregional snapshots of the long-term responses of coral assemblages to restoration

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    Coral restoration is rapidly becoming a mainstream strategic reef management response to address dramatic declines in coral cover worldwide. Restoration success can be defined as enhanced reef functions leading to improved ecosystem services, with multiple benefits at socio-ecological scales. However, there is often a mismatch between the objectives of coral restoration programs and the metrics used to assess their effectiveness. In particular, the scales of ecological benefits currently assessed are typically limited in both time and space, often being limited to short-term monitoring of the growth and survival of transplanted corals. In this paper, we explore reef-scale responses of coral assemblages to restoration practices applied in four well-established coral restoration programs. We found that hard coral cover and structural complexity were consistently greater at restored compared to unrestored (degraded) sites. However, patterns in coral diversity, coral recruitment, and coral health among restored, unrestored, and reference sites varied across locations, highlighting differences in methodologies among restoration programs. Altogether, differences in program objectives, methodologies, and the state of nearby coral communities were key drivers of variability in the responses of coral assemblages to restoration. The framework presented here provides guidance to improve qualitative and quantitative assessments of coral restoration efforts and can be applied to further understanding of the role of restoration within resilience-based reef management

    Differences in Ultrasonic Vocalizations between Wild and Laboratory California Mice (Peromyscus californicus)

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    BACKGROUND: Ultrasonic vocalizations (USVs) emitted by muroid rodents, including laboratory mice and rats, are used as phenotypic markers in behavioral assays and biomedical research. Interpretation of these USVs depends on understanding the significance of USV production by rodents in the wild. However, there has never been a study of muroid rodent ultrasound function in the wild and comparisons of USVs produced by wild and laboratory rodents are lacking to date. Here, we report the first comparison of wild and captive rodent USVs recorded from the same species, Peromyscus californicus. METHODOLOGY AND PRINCIPAL FINDINGS: We used standard ultrasound recording techniques to measure USVs from California mice in the laboratory (Peromyscus Genetic Stock Center, SC, USA) and the wild (Hastings Natural History Reserve, CA, USA). To determine which California mouse in the wild was vocalizing, we used a remote sensing method that used a 12-microphone acoustic localization array coupled with automated radio telemetry of all resident Peromyscus californicus in the area of the acoustic localization array. California mice in the laboratory and the wild produced the same types of USV motifs. However, wild California mice produced USVs that were 2-8 kHz higher in median frequency and significantly more variable in frequency than laboratory California mice. SIGNIFICANCE: The similarity in overall form of USVs from wild and laboratory California mice demonstrates that production of USVs by captive Peromyscus is not an artifact of captivity. Our study validates the widespread use of USVs in laboratory rodents as behavioral indicators but highlights that particular characteristics of laboratory USVs may not reflect natural conditions

    Citizen Science for Earth Observation (Citzens4EO): Understanding Current Use in the UK

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    The role of Earth observation (EO) data in addressing societal problems from environmental through to humanitarian should not be understated. Recent innovation in EO means provision of analysis ready data and data cubes, which allows for rapid use of EO data. This in combination with processing technologies such as Google Earth Engine and open source algorithms/software for EO data integration and analyses has afforded an explosion of information to answer research questions and/or inform policy making. However, there is still a need for both training and validation data within EO projects – often this can be challenging to obtain. It has been suggested that citizen science can help here to provide these data, yet there is some perceived hesitancy in using citizen science within EO projects. This paper reports on the Citizen Science 4 EO (Citizens4EO) project that aimed to obtain an in-depth understanding of researchers’ and practitioners’ experiences with citizen science data in EO within the UK. Through a mixed methods approach (online and in-depth surveys and a spotlight case study) it was found that although the benefits of using citizen science data in EO projects were many (and highlighted in the spotlighted “Slavery from Space” case study), there were a number of common concerns around using citizen science. These were around the mechanics of deploying citizen science and the unreliability of a potentially misinformed or undertrained citizen base. As such, comparing the results of this study with those of a similar survey undertaken in 2016, it is apparent that progress towards optimising citizen science use in EO has been incremental but positive with evidence of the realisation of the benefits of citizen science for EO (Citizens4EO). As such, we conclude by offering priority action areas to support further use of citizen science by the EO community within the UK, which ultimately should be adopted further afield

    Adolescent Brain Cognitive Development (ABCD) Study Linked External Data (LED): Protocol and practices for geocoding and assignment of environmental data

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    Our brain is constantly shaped by our immediate environments, and while some effects are transient, some have long-term consequences. Therefore, it is critical to identify which environmental risks have evident and long-term impact on brain development. To expand our understanding of the environmental context of each child, the Adolescent Brain Cognitive Development (ABCD) Study® incorporates the use of geospatial location data to capture a range of individual, neighborhood, and state level data based on the child\u27s residential location in order to elucidate the physical environmental contexts in which today\u27s youth are growing up. We review the major considerations and types of geocoded information incorporated by the Linked External Data Environmental (LED) workgroup to expand on the built and natural environmental constructs in the existing and future ABCD Study data releases. Understanding the environmental context of each youth furthers the consortium\u27s mission to understand factors that may influence individual differences in brain development, providing the opportunity to inform public policy and health organization guidelines for child and adolescent health
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