2,108 research outputs found

    Molecular Theory of Hydrophobic Effects: ``She is too mean to have her name repeated.''

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    This paper reviews the molecular theory of hydrophobic effects relevant to biomolecular structure and assembly in aqueous solution. Recent progress has resulted in simple, validated molecular statistical thermodynamic theories and clarification of confusing theories of decades ago. Current work is resolving effects of wider variations of thermodynamic state, e.g. pressure denaturation of soluble proteins, and more exotic questions such as effects of surface chemistry in treating stability of macromolecular structures in aqueous solutionComment: submitted to Ann. Rev. Phys. Chem., 31 pages, 245 references, 2 figure

    Investigation of the phase behaviour of the 1: 1 adduct of mesitylene and hexafluorobenzene

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    Variable temperature X-ray diffraction has been used to probe the structure and dynamics of the solid adducts of 1,3,5-trimethylbenzene (mesitylene) and hexafluorobenzene. PXRD patterns and DSC traces of near equimolar mixtures reveal two solid-state phase-transitions at 179.2 K and 111.0 K. The crystal structures of all three solid phases of this material have been solved by SXD. In contrast to previous studies on the adduct benzene–hexafluorobenzene, there is pairing of the mesitylene and hexafluorobenzene molecules in all three phases, each consisting of close-packed parallel columns of alternating C6H3(CH3)3 and C6F6 molecules packed face to face in a staggered conformation. Differences in structure between the phases illustrate the subtle interplay of quadrupole versus bond-dipole electrostatic interactions

    Metabonomics and Intensive Care

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    This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency medicine 2016. Other selected articles can be found online at http://www.biomedcentral.com/collections/annualupdate2016. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901

    The utilization and safety of umeclidinium and umeclidinium/vilanterol in UK primary care: a retrospective cohort study

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    Background: Umeclidinium bromide (UMEC) and umeclidinium/vilanterol (UMEC/VI) received European approval for maintenance treatment of patients with chronic obstructive pulmonary disease (COPD) in 2014. This study examined prescribing patterns, possible off-label prescribing, potential safety-related outcomes and adherence of these medications in routine clinical practice post-approval. Methods: This retrospective, multi-database, longitudinal observational study of new users of UMEC, UMEC/VI, or other long-acting bronchodilators (LABD) analyzed data from UK electronic health record databases (primary care cohort), linked to hospital data (linked cohort). Off-label prescribing, safety outcomes (cardiovascular, respiratory, and mortality), treatment patterns, and medication adherence were assessed. Results: In the primary care cohort (new users of UMEC n=3875; UMEC/VI n=2224; other LABD n=32,809), two-thirds of UMEC users were prescribed concomitant inhaled corticosteroids/long-acting β2-agonists. Possible off-label prescribing, defined as use in patients without COPD, was similar for UMEC (7.0%) and UMEC/VI (8.8%), but higher for new users of other LABD (18.0%). There were 547 UMEC users and 512 UMEC/VI users in the linked cohort. In both cohorts, incidence rates (IRs) of cardiovascular outcomes were similar for UMEC and UMEC/VI users (myocardial infarction IR per 1000 person-years [95% CIs]: UMEC 6.9 [4.4, 10.2]; UMEC/VI 6.8 [3.5, 11.9]). IRs of pneumonia and acute COPD exacerbations (AECOPD) were slightly higher among UMEC users compared with UMEC/VI users (AECOPD IR per 1000 person-years [95% CIs]: UMEC 979 [931, 1030]; UMEC/VI 746 [687, 811]). Adherence (medication possession ratio ≥ 80%) was 64% for UMEC and UMEC/VI. Conclusion: Most new users of UMEC were receiving multiple-inhaler triple therapy. Off-label prescribing was uncommon for new users of UMEC and UMEC/VI. Incidence of cardiovascular and respiratory outcomes was as expected for these drug classes. This study provides evidence that UMEC and UMEC/VI are being prescribed appropriately and their safety profile remains unchanged

    Direct Measurement of Nuclear Dependence of Charged Current Quasielastic-like Neutrino Interactions using MINERvA

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    Charged-current νμ\nu_{\mu} interactions on carbon, iron, and lead with a final state hadronic system of one or more protons with zero mesons are used to investigate the influence of the nuclear environment on quasielastic-like interactions. The transfered four-momentum squared to the target nucleus, Q2Q^2, is reconstructed based on the kinematics of the leading proton, and differential cross sections versus Q2Q^2 and the cross-section ratios of iron, lead and carbon to scintillator are measured for the first time in a single experiment. The measurements show a dependence on atomic number. While the quasielastic-like scattering on carbon is compatible with predictions, the trends exhibited by scattering on iron and lead favor a prediction with intranuclear rescattering of hadrons accounted for by a conventional particle cascade treatment. These measurements help discriminate between different models of both initial state nucleons and final state interactions used in the neutrino oscillation experiments

    Verticalization of bacterial biofilms

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    Biofilms are communities of bacteria adhered to surfaces. Recently, biofilms of rod-shaped bacteria were observed at single-cell resolution and shown to develop from a disordered, two-dimensional layer of founder cells into a three-dimensional structure with a vertically-aligned core. Here, we elucidate the physical mechanism underpinning this transition using a combination of agent-based and continuum modeling. We find that verticalization proceeds through a series of localized mechanical instabilities on the cellular scale. For short cells, these instabilities are primarily triggered by cell division, whereas long cells are more likely to be peeled off the surface by nearby vertical cells, creating an "inverse domino effect". The interplay between cell growth and cell verticalization gives rise to an exotic mechanical state in which the effective surface pressure becomes constant throughout the growing core of the biofilm surface layer. This dynamical isobaricity determines the expansion speed of a biofilm cluster and thereby governs how cells access the third dimension. In particular, theory predicts that a longer average cell length yields more rapidly expanding, flatter biofilms. We experimentally show that such changes in biofilm development occur by exploiting chemicals that modulate cell length.Comment: Main text 10 pages, 4 figures; Supplementary Information 35 pages, 15 figure

    Nanostructured 3D Constructs Based on Chitosan and Chondroitin Sulphate Multilayers for Cartilage Tissue Engineering

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    Nanostructured three-dimensional constructs combining layer-by-layer technology (LbL) and template leaching were processed and evaluated as possible support structures for cartilage tissue engineering. Multilayered constructs were formed by depositing the polyelectrolytes chitosan (CHT) and chondroitin sulphate (CS) on either bidimensional glass surfaces or 3D packet of paraffin spheres. 2D CHT/CS multi-layered constructs proved to support the attachment and proliferation of bovine chondrocytes (BCH). The technology was transposed to 3D level and CHT/CS multi-layered hierarchical scaffolds were retrieved after paraffin leaching. The obtained nanostructured 3D constructs had a high porosity and water uptake capacity of about 300%. Dynamical mechanical analysis (DMA) showed the viscoelastic nature of the scaffolds. Cellular tests were performed with the culture of BCH and multipotent bone marrow derived stromal cells (hMSCs) up to 21 days in chondrogenic differentiation media. Together with scanning electronic microscopy analysis, viability tests and DNA quantification, our results clearly showed that cells attached, proliferated and were metabolically active over the entire scaffold. Cartilaginous extracellular matrix (ECM) formation was further assessed and results showed that GAG secretion occurred indicating the maintenance of the chondrogenic phenotype and the chondrogenic differentiation of hMSCs

    Robotic Wireless Sensor Networks

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    In this chapter, we present a literature survey of an emerging, cutting-edge, and multi-disciplinary field of research at the intersection of Robotics and Wireless Sensor Networks (WSN) which we refer to as Robotic Wireless Sensor Networks (RWSN). We define a RWSN as an autonomous networked multi-robot system that aims to achieve certain sensing goals while meeting and maintaining certain communication performance requirements, through cooperative control, learning and adaptation. While both of the component areas, i.e., Robotics and WSN, are very well-known and well-explored, there exist a whole set of new opportunities and research directions at the intersection of these two fields which are relatively or even completely unexplored. One such example would be the use of a set of robotic routers to set up a temporary communication path between a sender and a receiver that uses the controlled mobility to the advantage of packet routing. We find that there exist only a limited number of articles to be directly categorized as RWSN related works whereas there exist a range of articles in the robotics and the WSN literature that are also relevant to this new field of research. To connect the dots, we first identify the core problems and research trends related to RWSN such as connectivity, localization, routing, and robust flow of information. Next, we classify the existing research on RWSN as well as the relevant state-of-the-arts from robotics and WSN community according to the problems and trends identified in the first step. Lastly, we analyze what is missing in the existing literature, and identify topics that require more research attention in the future
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