264 research outputs found

    On the thermodynamic origin of metabolic scaling

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    This work has been funded by projects AYA2013-48623-C2-2, FIS2013-41057-P, CGL2013-46862-C2-1-P and SAF2015-65878-R from the Spanish Ministerio de Economa y Competitividad and PrometeoII/2014/086, PrometeoII/2014/060 and PrometeoII/2014/065 from the Generalitat Valenciana (Spain). BL acknowledges funding from a Salvador de Madariaga fellowship, and L.L. acknowledges funding from EPSRC Early Career fellowship EP/P01660X/1

    Peptide immobilisation on porous silicon surface for metal ions detection

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    In this work, a Glycyl-Histidyl-Glycyl-Histidine (GlyHisGlyHis) peptide is covalently anchored to the porous silicon PSi surface using a multi-step reaction scheme compatible with the mild conditions required for preserving the probe activity. In a first step, alkene precursors are grafted onto the hydrogenated PSi surface using the hydrosilylation route, allowing for the formation of a carboxyl-terminated monolayer which is activated by reaction with N-hydroxysuccinimide in the presence of a peptide-coupling carbodiimide N-ethyl-N'-(3-dimethylaminopropyl)-carbodiimide and subsequently reacted with the amino linker of the peptide to form a covalent amide bond. Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy are used to investigate the different steps of functionalization

    Scalable, Non-denaturing Purification of Phosphoproteins Using Ga³⁺-IMAC: N2A and M1M2 Titin Components as Study case

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    The purification of phosphorylated proteins in a folded state and in large enough quantity for biochemical or biophysical analysis remains a challenging task. Here, we develop a new implementation of the method of gallium immobilized metal chromatography (Ga3+-IMAC) as to permit the selective enrichment of phosphoproteins in the milligram scale and under native conditions using automated FPLC instrumentation. We apply this method to the purification of the UN2A and M1M2 components of the muscle protein titin upon being monophosphorylated in vitro by cAMP-dependent protein kinase (PKA). We found that UN2A is phosphorylated by PKA at its C-terminus in residue S9578 and M1M2 is phosphorylated in its interdomain linker sequence at position T32607. We demonstrate that the Ga3+-IMAC method is efficient, economical and suitable for implementation in automated purification pipelines for recombinant proteins. The procedure can be applied both to the selective enrichment and to the removal of phosphoproteins from biochemical samples

    Trace analysis of environmental matrices by large-volume injection and liquid chromatography-mass spectrometry

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    The time-honored convention of concentrating aqueous samples by solid-phase extraction (SPE) is being challenged by the increasingly widespread use of large-volume injection (LVI) liquid chromatography–mass spectrometry (LC–MS) for the determination of traces of polar organic contaminants in environmental samples. Although different LVI approaches have been proposed over the last 40 years, the simplest and most popular way of performing LVI is known as single-column LVI (SC-LVI), in which a large-volume of an aqueous sample is directly injected into an analytical column. For the purposes of this critical review, LVI is defined as an injected sample volume that is ≥10% of the void volume of the analytical column. Compared with other techniques, SC-LVI is easier to set up, because it requires only small hardware modifications to existing autosamplers and, thus, it will be the main focus of this review. Although not new, SC-LVI is gaining acceptance and the approach is emerging as a technique that will render SPE nearly obsolete for many environmental applications.In this review, we discuss: the history and development of various forms of LVI; the critical factors that must be considered when creating and optimizing SC-LVI methods; and typical applications that demonstrate the range of environmental matrices to which LVI is applicable, for example drinking water, groundwater, and surface water including seawater and wastewater. Furthermore, we indicate direction and areas that must be addressed to fully delineate the limits of SC-LVI

    Smoking patterns and stimulus control in intermittent and daily smokers

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    Intermittent smokers (ITS) - who smoke less than daily - comprise an increasing proportion of adult smokers. Their smoking patterns challenge theoretical models of smoking motivation, which emphasize regular and frequent smoking to maintain nicotine levels and avoid withdrawal, but yet have gone largely unexamined. We characterized smoking patterns among 212 ITS (smoking 4-27 days per month) compared to 194 daily smokers (DS; smoking 5-30 cigarettes daily) who monitored situational antecedents of smoking using ecological momentary assessment. Subjects recorded each cigarette on an electronic diary, and situational variables were assessed in a random subset (n = 21,539 smoking episodes); parallel assessments were obtained by beeping subjects at random when they were not smoking (n = 26,930 non-smoking occasions). Compared to DS, ITS' smoking was more strongly associated with being away from home, being in a bar, drinking alcohol, socializing, being with friends and acquaintances, and when others were smoking. Mood had only modest effects in either group. DS' and ITS' smoking were substantially and equally suppressed by smoking restrictions, although ITS more often cited self-imposed restrictions. ITS' smoking was consistently more associated with environmental cues and contexts, especially those associated with positive or "indulgent" smoking situations. Stimulus control may be an important influence in maintaining smoking and making quitting difficult among ITS. © 2014 Shiffman et al

    How authentic leadership influences team performance:the mediating role of team reflexivity

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    This study examines how authentic leadership influences team performance via the mediating mechanism of team reflexivity. Adopting a self-regulatory perspective, we propose that authentic leadership will predict the specific team regulatory process of reflexivity, which in turn will be associated with two outcomes of team performance; effectiveness and productivity. Using survey data from 53 teams in three organizations in the United Kingdom and Greece and controlling for collective trust, we found support for our stated hypotheses with the results indicating a significant fully mediated relationship. As predicted the self-regulatory behaviors inherent in the process of authentic leadership served to collectively shape team behavior, manifesting in the process of team reflexivity, which, in turn, positively predicted team performance. We conclude with a discussion of how this study extends theoretical understanding of authentic leadership in relation to teamwork and delineate several practical implications for leaders and organizations
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