498 research outputs found

    Bloomfield Road Stormwater Storage Tanks Grouting Works, Blackpool, UK

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    Bloomfield Road Stormwater Storage Tanks, owned by United Utilities PLC, were constructed in 1999 in Blackpool UK to provide 60,000m3 of storage to prevent overflow discharges during the summer bathing water season. The asset comprises two buried tanks (36m diameter and 40m deep) constructed as circular diaphragm walls. Significant groundwater inflows with minor fines content and turbidity up to 48l/s have been reported entering one of the tanks since 2001. From 2008 an increase of fines ingress has been observed indicating potential for progressive failure of the underlying formation strata. The site stratigraphy comprises predominantly glacial superficial soils overlying an interlaminated Mudstone/Gypsum and Halite sequence. Groundwater inflows were likely to have initiated failure mechanisms in the formation strata including fines loss, dissolution of both gypsum and halite and potentially significant voiding. An innovative event tree risk analysis tool was developed to identify and allow a focused remedial works design and a cost effective solution to be planned. The main works implemented comprised: sealing of the base slab joint by resin injection; contact grouting beneath the base; ground investigation works including cross hole tomography geophysics; and grouting within the Mudstone formation. This paper describes the implementation of the project which was completed ahead of programme ensuring continue

    Accessible and sustainable Cu(0)-mediated radical polymerisation for the functionalisation of surfaces

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    Polymer brushes have great potential for use in functionalising surfaces due to their chemical and mechanical robustness, and wide variety of useful properties including antibacterial and antifouling behaviour. One such grafted polymer of interest is poly[2-(methacryloyloxy)ethyl]trimethylammonium chloride (PMETAC), shown to have excellent antibacterial behaviour due to the presence of quaternary ammonium chloride groups (QACs). Previous studies have shown that increasing the density of QACs increases the efficacy of these surfaces, therefore the production of thick PMETAC brushes is highly desirable. Cu(0)-mediated radical polymerisation (CuRP) offers a simple route to the production of these surfaces. A movement towards more sustainable chemistry has led to research into polymerisations in environmentally benign solvent, with focus placed on recycled and easily accessible catalysts. In this study, the growth of PMETAC brushes up to 300 nm dry thickness (∼ 425 nm water-swollen thickness) is demonstrated, thicker than any previous report we have found for this polymer brush. Furthermore, tap water is used as a cheap and readily available solvent, with a catalyst derived from copper wire. The use of copper wire, compared to the commonly used CuBr2 catalyst, leads to thicker coatings which also display a lower swelling ratio, implying an increased grafting density. The protocol can be continuously cycled over a 7-day period without changing the monomer solution or catalyst, with numerous wafers being functionalised over the time period with no significant reduction in grafted amount. In addition, the polymerisation can be carried out in ambient (non-inert) conditions with no degassing steps, again without with significant detriment to grafting

    When Do People Trust Their Social Groups?

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    Trust facilitates cooperation and supports positive outcomes in social groups, including member satisfaction, information sharing, and task performance. Extensive prior research has examined individuals' general propensity to trust, as well as the factors that contribute to their trust in specific groups. Here, we build on past work to present a comprehensive framework for predicting trust in groups. By surveying 6,383 Facebook Groups users about their trust attitudes and examining aggregated behavioral and demographic data for these individuals, we show that (1) an individual's propensity to trust is associated with how they trust their groups, (2) smaller, closed, older, more exclusive, or more homogeneous groups are trusted more, and (3) a group's overall friendship-network structure and an individual's position within that structure can also predict trust. Last, we demonstrate how group trust predicts outcomes at both individual and group level such as the formation of new friendship ties.Comment: CHI 201

    Field tests of a pond water treating system

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    Done under Department of Agricultural Engineering Research Project 155, 'Farm water supplies'--P. [2].Digitized 2007 AES.Includes bibliographical references (page 27)

    Oxford unicompartmental knee arthroplasty: medial pain and functional outcome in the medium term

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    <p>Abstract</p> <p>Background</p> <p>In our experience results of the Oxford unicompartmental knee replacement have not been as good as had been expected. A common post operative complaint is of persistent medial knee discomfort, it is not clear why this phenomenon occurs and we have attempted to address this in our study.</p> <p>Methods</p> <p>48 patients were retrospectively identified at a mean of 4.5 years (range = 3 to 6 years) following consecutive Oxford medial Unicompartmental Knee arthroplasties for varus anteromedial osteoarthritis. The mean age at implantation was 67 years (range 57-86). Of these 48 patients, 4 had died, 4 had undergone revision of their unicompartmental knee replacements and 2 had been lost to follow up leaving 38 patients with 40 replaced knees available for analysis using the 'new Oxford Knee Score' questionnaire. During assessment patients were asked specifically whether or not they still experienced medial knee discomfort or pain.</p> <p>Results</p> <p>The mean 'Oxford score' was only 32.7 (range = 16 to 48) and 22 of the 40 knees were uncomfortable or painful medially.</p> <p>The accuracy of component positioning was recorded, using standard post operative xrays, by summing the angulation or displacement of each component in two planes from the ideal position (according to the 'Oxford knee system radiographic criteria'). No correlation was demonstrated between the radiographic scores and the 'Oxford scores', or with the presence or absence of medial knee discomfort or pain.</p> <p>Conclusion</p> <p>In our hands the functional outcome following Oxford Unicompartmental knee replacement was variable, with a high incidence of medial knee discomfort which did not correlate with the postoperative radiographic scores, pre-op arthritis and positioning of the prosthesis.</p

    Toenail Manganese: A Sensitive and Specific Biomarker of Exposure to Manganese in Career Welders

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    Manganese (Mn) is an essential trace metal. It is also a component of welding fume. Chronic inhalation of manganese from welding fume has been associated with decreased neurological function. Currently, there is not a universally recognized biomarker for Mn exposure; however, hair and toenails have shown promise. In a cohort of 45 male welders and 35 age-matched factory control subjects, we assessed the sensitivity and specificity of toenail Mn to distinguish occupationally exposed subjects from unexposed controls. Further we examined the exposure time window that best correlates with the proposed biomarker, and investigated if non-occupational exposure factors impacted toenail Mn concentrations. Toenail clippings were analyzed for Mn using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Exposure to respirable Mn-containing particles (<4 µm) was estimated using an exposure model that combines personal air monitoring, work history information, and dietary intake to estimate an individual's exposure to Mn from inhalation of welding fume. We assessed the group differences in toenail concentrations using a Student's t-test between welders and control subjects and performed a receiver operating characteristic (ROC) curve analysis to identify a threshold in toenail concentration that has the highest sensitivity and specificity in distinguishing welders from control subjects. Additionally, we performed mixed-model regressions to investigate the association between different exposure windows and toenail Mn concentrations. We observed that toenail Mn concentrations were significantly elevated among welders compared to control subjects (6.87 ± 2.56 versus 2.70 ± 1.70 µg g-1; P < 0.001). Our results show that using a toenail Mn concentration of 4.14 µg g-1 as cutoff allows for discriminating between controls and welders with 91% specificity and 94% sensitivity [area under curve (AUC) = 0.98]. Additionally, we found that a threshold of 4.66 µg g-1 toenail Mn concentration enables a 90% sensitive and 90% specific discrimination (AUC = 0.96) between subjects with average exposure above or below the American Conference of Governmental Industrial Hygienist (ACGIH) Threshold Limit Value (TLV) of 0.02 mg m-3 during the exposure window of 7-12 months prior to the nail being clipped. Investigating which exposure window was best reflected by toenail Mn reproduced the result from another study of toenail Mn being significantly (P < 0.001) associated with exposure 7-12 months prior to the nail being clipped. Lastly, we found that dietary intake, body mass index, age, smoking status, and ethnicity had no significant effect on toenail Mn concentrations. Our results suggest that toenail Mn is a sensitive, specific, and easy-to-acquire biomarker of Mn exposure, which is feasible to be used in an industrial welder population

    Nanoscale electrochemical mapping

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    Surfaces and interfaces, of both practical and fundamental interest, have long been recognized to be complex, yet while there are many microscopy and spectroscopy methods for imaging structure, topography and surface chemical composition at high spatial resolution, there are relatively few techniques for mapping associated chemical fluxes in the near-interface region. In this regard, scanning electrochemical probe microscopy (SEPM), which utilizes a small scale electrode probe as an imaging device, has had a unique place in the scanning probe microscopy (SPM) family of techniques, in being able to map chemical fluxes and interfacial reactivity. For a long time, techniques such as scanning electrochemical microscopy (SECM) were largely stuck at the micron –or larger –scale in terms of spatial resolution, but recent years have seen spectacular progress, such that a variety of different types of SEPM technique are now available and 10sof nm spatial resolution is becoming increasingly accessible. This step-change in capability is opening many new opportunities for the characterization of flux processes and interfacial activity in a whole raft of systems, including electrode surfaces, electromaterials, soft matter, living cells and tissues

    Meta-Analysis of Perceived Stress and Its Association With Incident Coronary Heart Disease

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    Most studies examining potential associations between psychological factors and cardiovascular outcomes have focused on depression or anxiety. The effect of perceived stress on incident coronary heart disease (CHD) has yet to be reviewed systematically. We conducted a systematic review and meta-analysis of the association between perceived stress and incident CHD. Ovid, MEDLINE, and PsycINFO were searched as data sources. Prospective observational cohort studies were selected that measured self-reported perceived stress and assessed incident CHD at ≥6 months. We extracted study characteristics and estimates of the risk of incident CHD associated with high perceived stress versus low perceived stress. We identified 23 potentially relevant articles, of which 6 met our criteria (n = 118,696). Included studies measured perceived stress with validated measurements and nonvalidated simple self-report surveys. Incident CHD was defined as new diagnosis of, hospitalization for, or mortality secondary to CHD. Meta-analysis yielded an aggregate risk ratio of 1.27 (95% confidence interval 1.12 to 1.45) for the magnitude of the relation between high perceived stress and incident CHD. In conclusion, this meta-analysis suggests that high perceived stress is associated with a moderately increased risk of incident CHD
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