The influence of calcium, sodium and bicarbonate on the uptake of uranium onto nanoscale zero-valent iron particles

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.This work investigates the influence of calcium (Ca), sodium (Na) and bicarbonate (HCO3−) on the uptake of uranium (U) onto nanoscale zero-valent iron particles (nZVI). Solutions tested contained U at 1 mg/L, NaHCO3 ranging from 0 to 100 mg/L and CaCl2 or NaCl ranging from 625 to 719 mg/L to normalise the ionic strength. Mine water containing a similar concentration of U (1.03 mg/L) and HCO3− at 845 mg/L was also tested as a natural analogue. All solutions were stored in sealed glass jars in the open laboratory with headspace comprising ambient air. Results demonstrate Ca, Na and HCO3− as having no significant inhibitive influence on the efficacy of nZVI for initial U removal from solution, with ⩾95.7% uptake recorded for all systems studied after 0.5 h reaction. Similar U retention (>97.1%) was recorded throughout the entire 672 h experiment for all solutions with Ca absent. In contrast, partial U desorption in the latter stages of the experiment was recorded for all solutions with Ca present, with 87.3%, 85.2% and 84.7% removal recorded after 672 h for solutions containing 0, 10 and 100 mg/L HCO3−, respectively, and 10.9% removal recorded for the mine water. Maximum U removal onto nZVI was recorded as directly proportional to HCO3− concentration for solutions with Ca absent, however, no trend was identified for the Ca-bearing solutions. Overall results demonstrate Ca as having a significant inhibitive influence on the long-term retention (e.g. >48 h) of U on nZVI, which is independent of HCO3− concentration when also present at <100 mg/L.Engineering and Physical Sciences Research CouncilNAT

Nanoscale zero-valent iron particles for the remediation of plutonium and uranium contaminated solutions

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.In the current work the uptake of plutonium onto nanoscale zero-valent iron nanoparticles (nZVI) under anoxic conditions has been investigated. A uranyl solution was also studied under similar geochemical conditions to provide a comparative dataset. Following nZVI addition, a rapid and significant decrease in aqueous actinide concentration was recorded for both systems. The removal rate recorded for plutonium was slower, with 77% removal recorded after 1 h of reaction, compared to 99% recorded for uranium. Low aqueous contaminant concentrations (<25%) were then recorded for both systems until the end of the 7 day reaction period. XPS confirmed contaminant uptake onto the nZVI. For the plutonium system, the recorded photoelectron spectra exhibited Pu 4f lines centred at ∼439 and ∼427 eV, characteristic of Pu4+ and implying that chemical reduction of the sorbed plutonium had occurred, ascribed to the formation of PuO2. Similarly, with the U-system, the recorded U 4f photoelectron peaks were centred at energies of ∼380 and ∼391 eV, characteristic of U4+ in UO2. Results provide clear evidence that nZVI may be used as an effective material for the removal of plutonium from contaminated waters.AWE plcEngineering and Physical Sciences Research Counci

The potential of low-cost ROV for use in deep-sea mineral, ore prospecting and monitoring

With the development of ever more powerful micro-computers, the cost and capabilities of robotic systems for environmental surveying using remotely control systems continues to decrease and improve. Historically, submarine exploration was restricted to companies or organisations with considerable finances and resources; however, the last decade has seen the advent of ‘low cost’ remotely operated vehicles (ROV). These cost anywhere from $400-$40,000 and provide an opportunity for wider participation in ocean exploration. However, with 60% of the world's seafloor lying at depths in excess of 1000 m and current low cost ROVs typiclly depth limited to just 100 m, there is presently an inability to “go deep” affordably. This review assesses the state of the art for deep ROV technologies and identifies the primary technological hurdles to overcome in order to facilitate proliferation of low cost ROVs for deep ocean exploration with an emphasis on their application to mineral and ore prospecting

Adolescents' self-efficacy and digital health literacy: a cross-sectional mixed methods study.

BACKGROUND: The internet and social media are increasingly popular sources of health information for adolescents. Using online health information requires digital health literacy, consisting of literacy, analytical skills and personal capabilities such as self-efficacy. Appraising trustworthiness and relevance of online health information requires critical health literacy to discriminate between sources, critically analyse meaning and relevance, and use information for personal health. Adolescents with poor digital health literacy risk using misinformation, with potential negative health outcomes. We aimed to understand adolescents' contemporary digital health literacy and compared self-efficacy with capability. METHODS: Adolescents (12-17 years) completed an eHEALS self-report digital health literacy measure, a practical search task using a think-aloud protocol and an interview to capture perceived and actual digital health literacy. eHEALS scores were generated using descriptive statistics, search tasks were analysed using an observation checklist and interviews were thematically analysed based on Social Cognitive Theory, focussing on self-efficacy. RESULTS: Twenty-one participants generally had high self-efficacy using online health information but perceived their digital health literacy to be higher than demonstrated. They accessed online health information unintentionally on social media and intentionally via search engines. They appraised information medium, source and content using general internet searching heuristics taught at school. Information on social media was considered less trustworthy than websites, but participants used similar appraisal strategies for both; some search/appraisal heuristics were insufficiently nuanced for digital health information, sometimes resulting in misplaced trust or diminished self-efficacy. Participants felt anxious or relieved after finding online health information, depending on content, understanding and satisfaction. They did not act on information without parental and/or health professional advice. They rarely discussed findings with health professionals but would welcome discussions and learning how to find and appraise online health information. CONCLUSIONS: Whilst adolescents possess many important digital health literacy skills and generally feel self-efficacious in using them, their critical health literacy needs improving. Adolescents desire increased digital health literacy so they can confidently appraise health information they find online and on social media. Co-designed educational interventions with adolescents and health providers are required

In-situ, time resolved monitoring of uranium in BFS:OPC grout. Part 1: Corrosion in water vapour

Uranium encapsulated in grout was exposed to water vapour for extended periods of time. Through synchrotron x-ray powder difraction and tomography measurements, uranium dioxide was determined the dominant corrosion product over a 50-week time period. The oxide growth rate initiated rapidly, with rates comparable to the U+H2O reaction. Over time, the reaction rate decreased and eventually plateaued to a rate similar to the U+H2O+O2 reaction. This behaviour was not attributed to oxygen ingress, but instead the decreasing permeability of the grout, limiting oxidising species access to the metal surface

Influence of sex on the age‐related adaptations of neuromuscular function and motor unit properties in elite masters athletes

Motor unit (MU) remodelling acts to minimise loss of muscle fibres following denervation in older age, which may be more successful in masters athletes. Evidence suggests performance and neuromuscular function decline with age in this population, although the majority of studies have focused on males, with little available data on female athletes. Functional assessments of strength, balance and motor control were performed in 30 masters athletes (16 male) aged 44–83 years. Intramuscular needle electrodes were used to sample individual motor unit potentials (MUPs) and near‐fibre MUPs in the tibialis anterior (TA) during isometric contractions at 25% maximum voluntary contraction, and used to determine discharge characteristics (firing rate, variability) and biomarkers of peripheral MU remodelling (MUP size, complexity, stability). Multilevel mixed‐effects linear regression models examined effects of age and sex. All aspects of neuromuscular function deteriorated with age (P < 0.05) with no age × sex interactions, although males were stronger (P < 0.001). Indicators of MU remodelling also progressively increased with age to a similar extent in both sexes (P < 0.05), whilst MU firing rate progressively decreased with age in females (p = 0.029), with a non‐significant increase in males (p = 0.092). Masters athletes exhibit age‐related declines in neuromuscular function that are largely equal across males and females. Notably, they also display features of MU remodelling with advancing age, probably acting to reduce muscle fibre loss. The age trajectory of MU firing rate assessed at a single contraction level differed between sexes, which may reflect a greater tendency for females to develop a slower muscle phenotype

A Review of Current Coral Monitoring Tools/ Diagnostic Methods & Introducing a New Tool to the Coral Health Toolkit

Rapidly and repeatedly ascertaining the health status of coral reefs is an ever more pressing issue as part of activities to understand and monitor the damaging impacts of climate change. A combination of increasing ocean temperatures, acidity and frequency of extreme storm events continues to alter the marine environment beyond what sensitive organisms, such as coral, can cope with. It is therefore vital to establish technologies and validated methods to provide a metric or indication into the health of these organisms. There are currently many surveys and techniques used by coral scientists to uncover insights into the status and assessment of coral reefs, from colour wheels to multispectral satellite surveys. Here we outline an array of current techniques and methods focused specifically on coral monitoring and health diagnosis, ranging across the length scales from simple diver-based surveyance to satellite remote sensing. The technique of using hyperspectral fluorescence imaging is also introduced as a viable novel addition to aid and extend the current toolbox of available technologie

Structural effects in UO2_2 thin films irradiated with fission-energy Xe ions

Uranium dioxide thin films have been successfully grown on LSAT (Al$_{10}$La$_3$O$_{51}$Sr$_{14}$Ta$_7$) substrates by reactive magnetron sputtering. Irradiation by 92 MeV $^{129}$Xe$^{23+}$ ions to simulate fission damage that occurs within nuclear fuels caused microstructural and crystallographic changes. Initially flat and continuous thin films were produced by magnetron sputtering with a root mean square roughness of 0.35 nm determined by AFM. After irradiation, this roughness increased to 60-70 nm, with the films developing discrete microstructural features: small grains (~3 $\mu$m), along with larger circular (up to 40 $\mu$m) and linear formations with non-uniform composition according to the SEM, AFM and EDX results. The irradiation caused significant restructuring of the UO$_2$ films that was manifested in significant filmsubstrate mixing, observed through EDX analysis. Diffusion of Al from the substrate into the film in unirradiated samples was also observed.Engineering and Physical Sciences Research Council (Grant ID: EP/ I036400/1), Radioactive Waste Management Ltd (formerly the Radioactive Waste Management Directorate of the UK Nuclear Decommissioning Authority, contract NPO004411A-EPS02), Russian Foundation for Basic Research (projects 13-03-90916), CSAR, Grand Accelélérateur National d’Ions Lourds (GANIL) Caen France, French Network EMIR, CIMAP-CIRIL, M.V.Lomonosov Moscow State University Program of Development, CKP FMI IPCE RA