6,349 research outputs found

    Synthesis and mesomorphic properties of new heterocyclic liquidcrystals with Central Ester–Chalcone linkages

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    A series of new calamitic liquid crystals, 4-[3-(pyridin-4-yl)prop-2-enoyl]phenyl 4-alkyloxybenzoates, comprising a pyridyl core,ester–chalcone central linkage and terminal alkyloxy chain were synthesized and characterized. This series consists of four membersthat differ by the length of the alkyloxy chain (CnH2n+1O , where n = 10, 12, 14, 16). The structures of the title compounds wereelucidated using spectroscopic and spectrometric techniques, such as FT-IR, NMR (1H and13C) and EI-MS. The mesomorphicproperties were studied using differential scanning calorimetry and optical polarizing microscopy. The decyloxy-containing com-pound was found to be non-mesogenic, whilst the compounds containing n-dodecyloxy to n-hexadecyloxy chains exhibited anenantiotropic smectic A phase with a fan-shaped texture. From the structure–property relationship study, it was proposed that thenumber of carbons in the alkyloxy chain must be at least 12 (n ≥ 12) to generate the smectic phase in the corresponding substitutedArCOOArCOCH CHC5H4N compounds

    Effect of corticosteroid therapy on influenza-related mortality: a systematic review and meta-analysis

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    Background: Most studies have reported that corticosteroid therapy adversely influences influenza-related outcomes. Methods: Electronic databases were searched from inception to March 2013 for experimental and observational studies investigating systemic corticosteroid therapy for presumed influenza-associated complications. Meta-analysis of Observational Studies in Epidemiology guidelines were adopted. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using random-effects models, and heterogeneity was assessed using the I2 statistic. Quality of evidence was assessed using the Grading Assessment, Development, and Evaluation system. Results: We identified 16 eligible studies (3039 individuals), all of which were observational; 10 (1497 individuals) were included in the meta-analysis of mortality, of which 9 studied patients with 2009 pandemic influenza A virus subtype H1N1. Risk of bias was greatest in the comparability domain of the Newcastle–Ottawa scale, consistent with potential confounding by indication, and data specific to mortality were of low quality. Meta-analysis found an increased odds of mortality (OR, 2.12; 95% CI, 1.36–3.29) associated with corticosteroid therapy. Subgroup analysis of adjusted estimates from 4 studies with very low statistical heterogeneity found a similar association (OR, 2.58; 95% CI, 1.39–4.79). Conclusions: No completed clinical trials were identified. Evidence from observational studies, with important limitations, suggests that corticosteroid therapy for presumed influenza-associated complications is associated with increased mortality

    Effect of serviceability limits on optimal design of steel portal frames

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    The design of hot-rolled steel portal frames can be sensitive to serviceability deflection limits. In such cases, in order to reduce frame deflections, practitioners increase the size of the eaves haunch and / or the sizes of the steel sections used for the column and rafter members of the frame. This paper investigates the effect of such deflection limits using a real-coded niching genetic algorithm (RC-NGA) that optimizes frame weight, taking into account both ultimate as well as serviceability limit states. The results show that the proposed GA is efficient and reliable. Two different sets of serviceability deflection limits are then considered: deflection limits recommended by the Steel Construction Institute (SCI), which is based on control of differential deflections, and other deflection limits based on suggestions by industry. Parametric studies are carried out on frames with spans ranging between 15 m to 50 m and column heights between 5 m to 10 m. It is demonstrated that for a 50 m span frame, use of the SCI recommended deflection limits can lead to frame weights that are around twice as heavy as compared to designs without these limits

    Cauchy-Matern Model of Sea Surface Wind Speed at the Lake Worth, Florida

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    We study the Cauchy-Matern (CM) process with long-range dependence (LRD). The closed form of its power spectrum density (PSD) function is given. We apply it to model the autocovariance function (ACF) and the PSD of the sea surface wind speed (wind speed for short) observed in the Lake Worth, Florida, over the 1984–2006 period. The present results exhibit that the wind speed at the Lake Worth over 1984–2006 is of LRD. The present results exhibit that the CM process may yet be a novel model to fit the wind speed there

    Development of Fluorescent Probes for Cancer Cell Lines

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    Fluorescence imaging is a powerful tool that permits visualization of specific cell states within a population; however, existing methods for fluorescence labeling cannot be easily applied in many biological systems. Unlike antibodies, small molecule proteins can be cell permeable and therefore useful in live-cell and in vivo imaging experiments; moreover, small molecule probes do not require genetic manipulation of cells. Protein kinases are in many ways ideal targets for the development of selective fluorescent small molecule probes. This is because protein kinases are involved in most cellular processes and changes in their localization, accessibility, and abundance are associated with changes in cellular state. In addition, drug discovery and chemical biology efforts have in recent decades produced many selective, cell permeable small molecule ligands of specific cellular kinases. Here we describe our attempts to leverage existing, well-characterized kinase inhibitors to develop fluorescent small molecule probes for use as imaging tools in cancer biology. BODIPY-conjugated kinase inhibitors, such as Mps1-IN-11 and BI25362 were synthesized. Their inhibition ability and immunofluorescence staining were tested.3We demonstrated the utility of BI-BODIPY as a cell permeable probe for monitoring PLK localization. This result serves as the foundation for more sophisticated live-cell and in vivo imaging experiments that we are currently pursuing. This study also provides proof of concept for extension of this strategy to convert other small molecule kinase inhibitors to probes that can analogously be used to monitor localization of their respective kinases

    Full-sky ray-tracing simulation of weak lensing using ELUCID simulations: exploring galaxy intrinsic alignment and cosmic shear correlations

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    The intrinsic alignment of galaxies is an important systematic effect in weak-lensing surveys, which can affect the derived cosmological parameters. One direct way to distinguish different alignment models and quantify their effects on the measurement is to produce mocked weak-lensing surveys. In this work, we use full-sky ray-tracing technique to produce mock images of galaxies from the ELUCID NN-body simulation run with the WMAP9 cosmology. In our model we assume that the shape of central elliptical galaxy follows that of the dark matter halo, and spiral galaxy follows the halo spin. Using the mocked galaxy images, a combination of galaxy intrinsic shape and the gravitational shear, we compare the predicted tomographic shear correlations to the results of KiDS and DLS. It is found that our predictions stay between the KiDS and DLS results. We rule out a model in which the satellite galaxies are radially aligned with the center galaxy, otherwise the shear-correlations on small scales are too high. Most important, we find that although the intrinsic alignment of spiral galaxies is very weak, they induce a positive correlation between the gravitational shear signal and the intrinsic galaxy orientation (GI). This is because the spiral galaxy is tangentially aligned with the nearby large-scale overdensity, contrary to the radial alignment of elliptical galaxy. Our results explain the origin of detected positive GI term from the weak-lensing surveys. We conclude that in future analysis, the GI model must include the dependence on galaxy types in more detail.Comment: 23 pages, 13 figures, published in ApJ. Our mock galaxy catalog is available upon request by email to the author ([email protected], [email protected]

    Hot carrier extraction in CH3NH3PbI3 unveiled by pump-push-probe spectroscopy

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    Halide perovskites are promising materials for development in hot carrier (HC) solar cells, where the excess energy of above-bandgap photons is harvested before being wasted as heat to enhance device efficiency. Presently, HC separation and transfer processes at higher-energy states remain poorly understood. Here, we investigate the excited state dynamics in CH3NH3PbI3 using pump-push-probe spectroscopy. It has its intrinsic advantages for studying these dynamics over conventional transient spectroscopy, albeit complementary to one another. By exploiting the broad excited-state absorption characteristics, our findings reveal the transfer of HCs from these higher-energy states into bathophenanthroline (bphen), an energy selective organic acceptor far above perovskite's band edges. Complete HC extraction is realized only after overcoming the interfacial barrier formed at the heterojunction, estimated to be between 1.01 and 1.08 eV above bphen's lowest unoccupied molecular orbital level. The insights gained here are essential for the development of a new class of optoelectronics

    IL11 stimulates ERK/P90RSK to inhibit LKB1/AMPK and activate mTOR initiating a mesenchymal program in stromal, epithelial, and cancer cells

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    IL11 initiates fibroblast activation but also causes epithelial cell dysfunction. The mechanisms underlying these processes are not known. We report that IL11-stimulated ERK/P90RSK activity causes the phosphorylation of LKB1 at S325 and S428, leading to its inactivation. This inhibits AMPK and activates mTOR across cell types. In stromal cells, IL11-stimulated ERK activity inhibits LKB1/AMPK which is associated with mTOR activation, ⍺SMA expression, and myofibroblast transformation. In hepatocytes and epithelial cells, IL11/ERK activity inhibits LKB1/AMPK leading to mTOR activation, SNAI1 expression, and cell dysfunction. Across cells, IL11-induced phenotypes were inhibited by metformin stimulated AMPK activation. In mice, genetic or pharmacologic manipulation of IL11 activity revealed a critical role of IL11/ERK signaling for LKB1/AMPK inhibition and mTOR activation in fatty liver disease. These data identify the IL11/mTOR axis as a signaling commonality in stromal, epithelial, and cancer cells and reveal a shared IL11-driven mesenchymal program across cell types

    Entry of copycats of luxury brands

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    We develop a game-theoretic model to examine the entry of copycats and its implications by incorporating two salient features; these features are two product attributes, i.e., physical resemblance and product quality, and two consumer utilities, i.e., consumption utility and status utility. Our equilibrium analysis suggests that copycats with a high physical resemblance but low product quality are more likely to successfully enter the market by defying the deterrence of the incumbent. Furthermore, we show that higher quality can prevent the copycat from successfully entering the market. Finally, we show that the entry of copycats does not always improve consumer surplus and social welfare. In particular, when the quality of the copycat is sufficiently low, the loss in status utility from consumers of the incumbent product overshadows the small gain in consumption utility from buyers of the copycat, leading to an overall decrease in consumer surplus and social welfare. </jats:p
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