STRONTIUM ISOTOPE SYSTEMATICS AND GEOCHEMISTRY OF COAL UTILIZATION BY-PRODUCTS

Coal combustion for energy generation creates large quantities of solid coal utilization by-products (CUB), including fly ash, bottom ash, and flue gas desulfurization products. These materials are either used in environmental and industrial applications or stored adjacent to power plants. The development of new techniques to track and understand the behavior of CUB in the environment is essential to the safe utilization of coal. In this research, sequential leaching techniques are coupled with strontium (Sr) isotope analysis to investigate the influence of coal type and combustion process on the geochemical characteristics of CUB. Sequential leaches of water, acetic acid, and hydrochloric acid were carried out on a variety of CUB types. Systematic differences in 87Sr/86Sr ratios were observed (1) among different types of CUB, and (2) between leachates and their corresponding bulk CUB values. These differences can help elucidate the origins of the inorganic components of coal, as well as the transformations that occur during combustion. In addition, this study demonstrates for the first time that there are multiple sources of Sr in coal that remain isotopically distinct during combustion. The degree of isotopic homogenization induced during the formation of CUB appears to be controlled by the feed coal chemistry and the particular combustion technology used. The Sr isotope data, when combined with major and trace element results, suggest that a greater fraction of Sr is bound in detrital minerals in higher-rank coals, while authigenic minerals and organic complexes comprise the dominant form of Sr in lower-rank coals. Investigation of CUB produced from fluidized bed combustion (FBC) also demonstrates that the combustion process can strongly impact the behavior of the inorganic components of coal during utilization. The association of potentially toxic trace elements with certain soluble Sr-bearing phases in CUB make Sr isotopes a promising tool to trace the release of these species during interactions with water. Application of Sr isotopes to studies of coal and CUB could facilitate the development of better disposal techniques by serving as a robust tracer of CUB in the environment

The mineralogy, petrology, and composition of anomalous eucrite Emmaville

The Emmaville eucrite is a relatively poorly studied basaltic achondrite with an anomalous oxygen isotope signature. In this study, we report comprehensive mineralogical, petrographic, and geochemical data from Emmaville in order to understand its petrogenesis and relationship with the basaltic eucrites. Emmaville is an unusually fine-grained, hornfelsic-textured metabasalt with pervasive impact melt veins and mineral compositions similar to those of typical basaltic eucrites. The major and trace element bulk composition of Emmaville is also typical of a basaltic eucrite. Three separated individual lithologies were also analyzed for O isotopes; a dark gray fraction (E1), a shocked lithology (E2), and a lighter gray portion (E3). Fractions E1 and E2 shared similar O isotope compositions to the bulk sample (E-B), whereas the lighter gray portion (E3) is slightly elevated in Δ17O and significantly elevated in δ18O compared to bulk. No evidence for any exogenous material is observed in the thin sections, coupled with the striking compositional similarity to typical basaltic eucrites, appears to preclude a simple impact-mixing hypothesis. The O-isotopes of Emmaville are similar to those of Bunburra Rockhole, A-881394, and EET 92023, and thus distinct from the majority of the HEDs, despite having similarities in petrology, mineral, and bulk compositions. It would, therefore, seem plausible that all four of these samples are derived from a single HED-like parent body that is isotopically distinct from that of the HEDs (Vesta) but similar in composition

Size of the group IVA iron meteorite core: Constraints from the age and composition of Muonionalusta

The group IVA fractionally crystallized iron meteorites display a diverse range of metallographic cooling rates. These have been attributed to their formation in a metallic core, approximately 150 km in radius, that cooled to crystallization in the absence of any appreciable insulating mantle. Here we build upon this formation model by incorporating several new constraints. These include (i) a recent U-Pb radiometric closure age of <2.5 Myr after solar system formation for the group IVA iron Muonionalusta, (ii) new measurements and modeling of highly siderophile element compositions for a suite of IVAs, and (iii) consideration of the thermal effects of heating by the decay of the short-lived radionuclide 60Fe. Our model for the thermal evolution of the IVA core suggests that it was approximately 50 - 110 km in radius after being collisionally exposed. This range is due to uncertainties in the initial abundance of live 60Fe incorporated into the IVA core. Our models define a relationship between cooling rate and closure age, which is used to make several predictions that can be tested with future measurements. In general, our results show that diverse cooling rates and early U-Pb closure ages can only coexist on mantle-free bodies and that energy released by the decay of 60Fe reduces the core size necessary to produce diverse metallographic cooling rates. The influence of 60Fe on cooling rates has largely been neglected in previous core formation models; accounting for this heat source can affect size estimates for other iron meteorite cores that cooled to crystallization in the presence of live 60Fe. Candidates for such a scenario of early, mantle-free formation include the iron IIAB, IIIAB and IVB groups.Comment: 30 pages, 3 figures, accepted to Earth and Planetary Science Letter

Impact of parental emotional support and coercive control on adolescents' self-esteem and psychological distress : results of a four-year longitudinal study

This study aims at investigating the impact of parental practices on youths’ adjustment. In all, 605 adolescents completed questionnaires at ages 14, 16 and 18. Self-esteem, psychological distress as well as parental emotional support and coercive control were measured. Analyses based on individual growth models revealed that self-esteem increased with age, but psychological distress remained stable over time. Boys reported higher levels of self-esteem and lower levels of psychological distress than girls. Maternal and paternal emotional support reinforced self-esteem over time. Maternal coercive control undermined self-esteem, but only at ages 16 and 18. Psychological distress decreased with parental emotional support but increased with parental coercive control at ages 14, 16 and 18. Overall, these results indicate that positive parental practices are related to youths’ well-being. These findings support the importance of establishing intervention strategies designed to promote best practices among parents of teenagers to help them develop into well-adjusted adults

Principles of Hand Fracture Management

The hand is essential in humans for physical manipulation of their surrounding environment. Allowing the ability to grasp, and differentiated from other animals by an opposing thumb, the main functions include both fine and gross motor skills as well as being a key tool for sensing and understanding the immediate surroundings of their owner

The association between social capital and mental health and behavioural problems in children and adolescents: an integrative systematic review

Background Mental health is an important component of overall health and wellbeing and crucial for a happy and meaningful life. The prevalence of mental health problems amongst children and adolescent is high; with estimates suggesting 10-20% suffer from mental health problems at any given time. These mental health problems include internalising (e.g. depression and social anxiety) and externalising behavioural problems (e.g. aggression and anti-social behaviour). Although social capital has been shown to be associated with mental health/behavioural problems in young people, attempts to consolidate the evidence in the form of a review have been limited. This integrative systematic review identified and synthesised international research findings on the role and impact of family and community social capital on mental health/behavioural problems in children and adolescents to provide a consolidated evidence base to inform future research and policy development. Methods Nine electronic databases were searched for relevant studies and this was followed by hand searching. Identified literature was screened using review-specific inclusion/exclusion criteria, the data were extracted from the included studies and study quality was assessed. Heterogeneity in study design and outcomes precluded meta-analysis/meta-synthesis, the results are therefore presented in narrative form. Results After screening, 55 studies were retained. The majority were cross-sectional surveys and were conducted in North America (n = 33); seven were conducted in the UK. Samples ranged in size from 29 to 98,340. The synthesised results demonstrate that family and community social capital are associated with mental health/behavioural problems in children and adolescents. Positive parent–child relations, extended family support, social support networks, religiosity, neighbourhood and school quality appear to be particularly important. Conclusions To date, this is the most comprehensive review of the evidence on the relationships that exist between social capital and mental health/behavioural problems in children and adolescents. It suggests that social capital generated and mobilised at the family and community level can influence mental health/problem behaviour outcomes in young people. In addition, it highlights key gaps in knowledge where future research could further illuminate the mechanisms through which social capital works to influence health and wellbeing and thus inform policy development

Geochemical and Strontium Isotope Characterization of Produced Waters from Marcellus Shale Natural Gas Extraction

Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Formation produced waters with other waters in the Appalachian Basin in the event of an accidental release, and to provide information about the source of the dissolved solids. Strontium isotopic ratios of Marcellus produced waters collected over a geographic range of ∼375 km from southwestern to northeastern Pennsylvania define a relatively narrow set of values (εSr SW = +13.8 to +41.6, where εSr SW is the deviation of the 87Sr/86Sr ratio from that of seawater in parts per 104); this isotopic range falls above that of Middle Devonian seawater, and is distinct from most western Pennsylvania acid mine drainage and Upper Devonian Venango Group oil and gas brines. The uniformity of the isotope ratios suggests a basin-wide source of dissolved solids with a component that is more radiogenic than seawater. Mixing models indicate that Sr isotope ratios can be used to sensitively differentiate between Marcellus Formation produced water and other potential sources of TDS into ground or surface waters

Could a brief assessment of negative emotions and self-esteem identify adolescents at current and future risk of self-harm in the community? A prospective cohort analysis

Background: Self-harm is common in adolescents, but it is often unreported and undetected. Available screening tools typically ask directly about self-harm and suicidal ideation. Although in an ideal world, direct enquiry and open discussion around self-harm would be advocated, non-psychiatric professionals in community settings are often reluctant to ask about this directly and disclosure can be met with feeling of intense anxiety. Training non-specialist staff to directly ask about self-harm has limited effects suggesting that alternative approaches are required. This study investigated whether a targeted analysis of negative emotions and self-esteem could identify young adolescents at risk of self-harm in community settings. Methods: Data were collected as part of a clinical trial from young people in school years 8–11 (aged 12–16) at eight UK secondary schools (N = 4503 at baseline, N = 3263 in prospective analysis). The Short Mood and Feelings Questionnaire, Revised Child Anxiety and Depression Scale, Rosenberg Self-Esteem Scale, personal failure (Children’s Automatic Thoughts Scale), and two items on self-harm were completed at baseline, 6 and 12 months. Results: Following a process of Principal Components Analysis, item reduction, and logistic regression analysis, three internally reliable factors were identified from the original measures that were independently associated with current and future self-harm; personal failure (3 items), physical symptoms of depression/anxiety (6 items), positive self-esteem (5 items). The summed score of these 14 items had good accuracy in identifying current self-harm (AUC 0.87 girls, 0.81 boys) and at six months for girls (0.81), and fair accuracy at six months for boys (AUC 0.74) and 12 months for girls (AUC 0.77). Conclusions: A brief and targeted assessment of negative emotions and self-esteem, focusing on factors that are strongly associated with current and future self-harm, could potentially be used to help identify adolescents who are at risk in community settings. Further research should assess the psychometric properties of the items identified and test this approach in more diverse community contexts