1,001 research outputs found

    Bicontinuous minimal surface nanostructures for polymer blend solar cells

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    This paper presents the first examination of the potential for bicontinuous structures such as the gyroid structure to produce high efficiency solar cells based on conjugated polymers. The solar cell characteristics are predicted by a simulation model that shows how the morphology influences device performance through integration of all the processes occurring in organic photocells in a specified morphology. In bicontinuous phases, the surface de. ning the interface between the electron and hole transporting phases divides the volume into two disjoint subvolumes. Exciton loss is reduced because the interface at which charge separation occurs permeates the device so excitons have only a short distance to reach the interface. As each of the component phases is connected, charges will be able to reach the electrodes more easily. In simulations of the current-voltage characteristics of organic cells with gyroid, disordered blend and vertical rod (rods normal to the electrodes) morphologies, we find that gyroids have a lower than anticipated performance advantage over disordered blends, and that vertical rods are superior. These results are explored thoroughly, with geminate recombination, i.e. recombination of charges originating from the same exciton, identified as the primary source of loss. Thus, if an appropriate materials choice could reduce geminate recombination, gyroids show great promise for future research and applications

    Nanocrystalline silicon oxide interlayer in monolithic perovskite silicon heterojunction tandem solar cells with total current density gt;39 mA cm2

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    Silicon heterojunction solar cells are implemented as bottom cells in monolithic perovskite silicon tandem solar cells. Commonly they are processed with a smooth front side to facilitate wet processing of the lead halide perovskite cell on top. The inherent drawback of this design, namely, enhanced reflection of the cell, can be significantly reduced by replacing the amorphous or nanocrystalline silicon front side n layer of the silicon cell by a nanocrystalline silicon oxide n layer. It is deposited with the same commonly used plasma enhanced chemical vapor deposition and can be tuned to feature opto electrical properties for enhanced light coupling into the Si bottom cell, namely, low parasitic absorption and an intermediate refractive index of 2.6. We demonstrate that a 80 100 nm thick layer results in 0.9 mA cm 2 current gain in the bottom cell yielding tandem cells with a top cell bottom cell total current above 39 mA cm 2 . These first nc SiO x H coupled tandem cells reach an efficiency gt;23.

    Callers’ attitudes and experiences of UK breastfeeding helpline support

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    Background: Breastfeeding peer support, is considered to be a key intervention for increasing breastfeeding duration rates. Whilst a number of national organisations provide telephone based breastfeeding peer support, to date there have been no published evaluations into callers’ experiences and attitudes of this support. In this study we report on the descriptive and qualitative insights provided by 908 callers as part of an evaluation of UK-based breastfeeding helpline(s). Methods: A structured telephone interview, incorporating Likert scale responses and open-ended questions was undertaken with 908 callers over May to August, 2011 to explore callers’ experiences of the help and support received via the breastfeeding helpline(s). Results: Overall satisfaction with the helpline was high, with the vast majority of callers’ recalling positive experiences of the help and support received. Thematic analysis was undertaken on all qualitative and descriptive data recorded during the evaluation, contextualised within the main areas addressed within the interview schedule in terms of ‘contact with the helplines’; ‘experiences of the helpline service’, ‘perceived effectiveness of support provision’ and ‘impact on caller wellbeing’. Conclusion: Callers valued the opportunity for accessible, targeted, non-judgmental and convenient support. Whilst the telephone support did not necessarily influence women’s breastfeeding decisions, the support they received left them feeling reassured, confident and more determined to continue breastfeeding. We recommend extending the helpline service to ensure support can be accessed when needed, and ongoing training and support for volunteers. Further advertising and promotion of the service within wider demographic groups is warranted

    Characterization of carbon nanotube–thermotropic nematic liquid crystal composites

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    Dispersions of carbon nanotubes (CNTs) in liquid crystals (LCs) have attracted attention due to their unique properties and possible applications in photonics and electronics. However, these are hard to stabilize, and the loading level in the equilibrium state in LC hosts is small. A practical way to monitor the quality and CNT incorporation in such equilibrium dispersions is required. Here, we compare different methods for characterising equilibrium CNT–LC composite materials

    Combined heart-liver transplantation for failing Fontan circulation in a late survivor with single-ventricle physiology

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    Management of adults with failing Fontan physiology poses many challenges, especially as transplantation offers the only realistic alternative to palliative care. We present the first combined heart and liver transplant performed in Europe, for a late survivor of single ventricle palliation with the Fontan circulation. In addition to the conventional medical and surgical challenges posed, we highlight the management of the associated multi-organ failure with focus on the liver and novel strategies for assessment and optimization

    Building social capital through breastfeeding peer support: Insights from an evaluation of a voluntary breastfeeding peer support service in North-West England

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    Background: Peer support is reported to be a key method to help build social capital in communities. To date there are no studies that describe how this can be achieved through a breastfeeding peer support service. In this paper we present findings from an evaluation of a voluntary model of breastfeeding peer support in North-West England to describe how the service was operationalized and embedded into the community. This study was undertaken from May, 2012 to May, 2013. Methods: Interviews (group or individual) were held with 87 participants: 24 breastfeeding women, 13 peer supporters and 50 health and community professionals. The data contained within 23 monthly monitoring reports (January, 2011 to February 2013) compiled by the voluntary peer support service were also extracted and analysed. Results: Thematic analysis was undertaken using social capital concepts as a theoretical lens. Key findings were identified to resonate with ’bonding’, ‘bridging’ and ‘linking’ forms of social capital. These insights illuminate how the peer support service facilitates ‘bonds’ with its members, and within and between women who access the service; how the service ‘bridges’ with individuals from different interests and backgrounds, and how ‘links’ were forged with those in authority to gain access and reach to women and to promote a breastfeeding culture. Some of the tensions highlighted within the social capital literature were also identified. Conclusions: Horizontal and vertical relationships forged between the peer support service and community members enabled peer support to be embedded into care pathways, helped to promote positive attitudes to breastfeeding and to disseminate knowledge and maximise reach for breastfeeding support across the community. Further effort to engage with those of different ethnic backgrounds and to resolve tensions between peer supporters and health professionals is warranted

    Animal, Plant, Collagen and Blended Dietary Proteins: Effects on Musculoskeletal Outcomes

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    This is the final version. Available from MDPI via the DOI in this record.Dietary protein is critical for the maintenance of musculoskeletal health, whereappropriate intake (i.e., source, dose, timing) can mitigate declines in muscle and bone mass and/orfunction. Animal-derived protein is a potent anabolic source due to rapid digestion and absorptionkinetics stimulating robust increases in muscle protein synthesis and promoting bone accretion andmaintenance. However, global concerns surrounding environmental sustainability has led to anincreasing interest in plant- and collagen-derived protein as alternative or adjunct dietary sources.This is despite the lower anabolic profile of plant and collagen protein due to the inferior essentialamino acid profile (e.g., lower leucine content) and subordinate digestibility (versus animal). Thisreview evaluates the efficacy of animal-, plant- and collagen-derived proteins in isolation, and asprotein blends, for augmenting muscle and bone metabolism and health in the context of ageing,exercise and energy restriction.Medical Research Council (MRC)National Institute for Health Researc

    Factors shaping prayer frequency among 9- to 11-year-olds

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    This paper begins by reviewing the evidence from international research concerning the personal and social correlates of prayer frequency during childhood and adolescence. Overall these data continue to support the view that young people who pray not only report higher levels of personal wellbeing but also report higher levels of pro-social attitudes. These findings raise a research question of particular relevance within church schools regarding the factors that predict higher levels of prayer activity among students. The Student Voice Project offers data that can illuminate this research question. Among the 3,101 9- to 11-year old students who participated in the project 11% prayed daily, 9% at least once a week, 32% sometimes, 11% once or twice a year, and 37% never. The present paper tests the power of four sets of predictor variables to account for individual differences in prayer frequency among these students: personal factors (age and sex), psychological factors (using the three dimensional model of personality proposed by Eysenck), church attendance (self, mother, and father), and family discussion about prayer (mother, father, and grandparents). Multiple regression analyses identified the discussion of prayer with the mother as the single most important predictor. These findings locate the development of the practice of prayer within the home, even more than within the church

    The socialist blues? Citizenship, class and civil society

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    This article seeks to explore the relationship between the British labour movement, the Left and the Labour party. It does so through the intellectual prism of debates around citizenship and civil society. In this respect, I seek to recover a critical politics around questions of class from the New Left who were always critical of more mainstream ideas of citizenship. However, I also point to the limitations of those who have argued that meaningful forms of citizenship can no longer be connected to political parties and only occurs outside of state organizations. Political parties continue to need intellectual narratives to legitimate their role in society and to connect with the broader civil order.The Labour Party in this respect has seemingly broken with ‘New Labour’ and is searching for a new narrative. The rise of an intellectual grouping around ‘Blue Labour’ has made considerable headway recently and I seek to take a critical view of some of their ideas and ethical frameworks. Here I argue that changing class formations and a more pluralistic society potentially ask difficult questions of those who seek to revive the labour movement in troubled times
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