458 research outputs found

    Synthesis of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) derivatives functionalised with two, four or eight hydroxyl groups

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    Short synthetic routes to a range of BEDT-TTF derivatives functionalised with two, four or eight hydroxyl groups are reported, of interest because of their potential for introducing hydrogen bonding between donor and anion into their radical cation salts. The cycloaddition of 1,3-dithiole-2,4,5-trithione with alkenes to construct 5,6-dihydro-1,3-dithiolo[4,5-b]1,4-dithiin-2-thiones is a key step, with homo- or hetero-coupling procedures and O-deprotection completing the syntheses. The first synthesis of a single diastereomer of tetrakis(hydroxymethyl)BEDT-TTF, the cis, trans product, was achieved by careful choice of O-protecting groups to facilitate separation of homo- and hetero-coupled products. Cyclisation of the trithione with enantiopure 1R,2R,5R,6R-bis(O,O-isopropylidene)hex-3-ene-1,2,5,6-tetrol (from D-mannitol) gave two separable diastereomeric thiones, which can be transformed to enantiomeric BEDT-TTF derivatives with four or eight hydroxyl groups

    The targeted delivery of multicomponent cargos to cancer cells by nanoporous particle-supported lipid bilayers.

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    Encapsulation of drugs within nanocarriers that selectively target malignant cells promises to mitigate side effects of conventional chemotherapy and to enable delivery of the unique drug combinations needed for personalized medicine. To realize this potential, however, targeted nanocarriers must simultaneously overcome multiple challenges, including specificity, stability and a high capacity for disparate cargos. Here we report porous nanoparticle-supported lipid bilayers (protocells) that synergistically combine properties of liposomes and nanoporous particles. Protocells modified with a targeting peptide that binds to human hepatocellular carcinoma exhibit a 10,000-fold greater affinity for human hepatocellular carcinoma than for hepatocytes, endothelial cells or immune cells. Furthermore, protocells can be loaded with combinations of therapeutic (drugs, small interfering RNA and toxins) and diagnostic (quantum dots) agents and modified to promote endosomal escape and nuclear accumulation of selected cargos. The enormous capacity of the high-surface-area nanoporous core combined with the enhanced targeting efficacy enabled by the fluid supported lipid bilayer enable a single protocell loaded with a drug cocktail to kill a drug-resistant human hepatocellular carcinoma cell, representing a 10(6)-fold improvement over comparable liposomes

    Conceptual learning : the priority for higher education

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    The common sense notion of learning as the all-pervasive acquisition of new behaviour and knowledge, made vivid by experience, is an incomplete characterisation, because it assumes that the learning of behaviour and the learning of knowledge are indistinguishable, and that acquisition constitutes learning without reference to transfer. A psychological level of analysis is used to argue that conceptual learning should have priority in higher education

    Severe childhood malaria syndromes defined by plasma proteome profiles

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    BACKGROUND Cerebral malaria (CM) and severe malarial anemia (SMA) are the most serious life-threatening clinical syndromes of Plasmodium falciparum infection in childhood. Therefore it is important to understand the pathology underlying the development of CM and SMA, as opposed to uncomplicated malaria (UM). Different host responses to infection are likely to be reflected in plasma proteome-patterns that associate with clinical status and therefore provide indicators of the pathogenesis of these syndromes. METHODS AND FINDINGS Plasma and comprehensive clinical data for discovery and validation cohorts were obtained as part of a prospective case-control study of severe childhood malaria at the main tertiary hospital of the city of Ibadan, an urban and densely populated holoendemic malaria area in Nigeria. A total of 946 children participated in this study. Plasma was subjected to high-throughput proteomic profiling. Statistical pattern-recognition methods were used to find proteome-patterns that defined disease groups. Plasma proteome-patterns accurately distinguished children with CM and with SMA from those with UM, and from healthy or severely ill malaria-negative children. CONCLUSIONS We report that an accurate definition of the major childhood malaria syndromes can be achieved using plasma proteome-patterns. Our proteomic data can be exploited to understand the pathogenesis of the different childhood severe malaria syndromes

    On our own terms : the working conditions of internet-based sex workers in the UK

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    The sex industry is increasingly operated through online technologies, whether this is selling services online through webcam or advertising, marketing or organising sex work through the Internet and digital technologies. Using data from a survey of 240 internet-based sex workers (members of the National Ugly Mug reporting scheme in the UK), we discuss the working conditions of this type of work. We look at the basic working patterns, trajectories and everyday experiences of doing sex work via an online medium and the impact this has on the lives of sex workers. For instance, we look at levels of control individuals have over their working conditions, prices, clientele and services sold, and discuss how this is mediated online and placed in relation to job satisfaction. The second key finding is the experience of different forms of crimes individuals are exposed to such as harassment and blackmail via the new technologies. We explore the relationship internet-based sex workers have with the police and discuss how current laws in the UK have detrimental effects in terms of safety and access to justice. These findings are placed in the context of the changing landscape of sex markets as the digital turn determines the nature of the majority of commercial sex encounters. These findings contribute significantly to the populist coercion/choice political debates by demonstrating levels and types of agency and autonomy experienced by some sex workers despite working in a criminalized, precarious and sometimes dangerous context

    The color signature of the transit of HD 209458: Discrepancies between stellar atmospheric models and observations

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    Exoplanetary transits produce a double-horned color signature that is distinct from both binaries and blends and can thus be used to separate exoplanets from false positives in transit searches. Color photometry with precision sufficient to detect this signal in transits of HD 209458 is available in the literature. Analysis of these observations reveals that, while the signature does exhibit the expected shape, it is significantly stronger than PHOENIX atmospheric models predict.Comment: 4 pages, 3 figures, accepted to A&

    The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Background Power Spectrum at 148 and 218 GHz from the 2008 Southern Survey

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    We present measurements of the cosmic microwave background (CMB) power spectrum made by the Atacama Cosmology Telescope at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. Our results clearly show the second through the seventh acoustic peaks in the CMB power spectrum. The measurements of these higher-order peaks provide an additional test of the {\Lambda}CDM cosmological model. At l > 3000, we detect power in excess of the primary anisotropy spectrum of the CMB. At lower multipoles 500 < l < 3000, we find evidence for gravitational lensing of the CMB in the power spectrum at the 2.8{\sigma} level. We also detect a low level of Galactic dust in our maps, which demonstrates that we can recover known faint, diffuse signals.Comment: 19 pages, 13 figures. Submitted to ApJ. This paper is a companion to Hajian et al. (2010) and Dunkley et al. (2010
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