7,625 research outputs found

    Lipase activity in vesicular systems: Characterization of candida cylindracea lipase and its activity in polymerizable dialkylammonium surfactant vesicles

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    Lipase from Candida cylindracea (CCL) was incorporated into polymerizable positively charged dialkylammonium bromide surfactant vesicles. The enzyme was incorporated by the use of the dehydration-rehydration method or by incubation. In the latter case, trapping efficiencies of up to 100% could be obtained. Activities of free and vesicle-incorporated CCL were tested for three triglycerides: triacetin, tributyrin, and tricaprylin. Enzyme activity was lowest in homogeneous mixtures (triacetin and small concentrations of tributyrin) and highest in heterogeneous mixtures (tricaprylin and high concentrations of tributyrin). Entrapment in vesicular systems is advantageous, especially in homogeneous reaction mixtures and in the case of the production of insoluble fatty acid (caproate), because inhibition by the acid can be suppressed. The influence of several surface-active additives, including vesicles, on the activity of lipase in triglyceride assays was tested. Vesicles have a positive influence on the activity, whereas other positively charged additives act as inhibitors. In the case of tricaprylin assays, the positively charged additives increase the activity. Finally, tryptic digestion for free and incorporated CCL were compared. Free CCL is readily inactivated, whereas incorporated enzyme is protected from proteolytic degradation

    Improving temporal resolution of ultrafast electron diffraction by eliminating arrival time jitter induced by radiofrequency bunch compression cavities

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    The temporal resolution of sub-relativistic ultrafast electron diffraction (UED) is generally limited by radio frequency (RF) phase and amplitude jitter of the RF lenses that are used to compress the electron pulses. We theoretically show how to circumvent this limitation by using a combination of several RF compression cavities. We show that if powered by the same RF source and with a proper choice of RF field strengths, RF phases and distances between the cavities, the combined arrival time jitter due to RF phase jitter of the cavities is cancelled at the compression point. We also show that the effect of RF amplitude jitter on the temporal resolution is negligible when passing through the cavity at a RF phase optimal for (de)compression. This will allow improvement of the temporal resolution in UED experiments to well below 100 fs

    Kwalitatieve evaluatie van 10 jaar zorgcoördinatie en case management in de Oost-Vlaamse drughulpverlening: een rondvraag bij hulpverleners en cliënten

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    Sinds 10 jaar wordt door de Provincie Oost-Vlaanderen – in samenwerking met het provinciaal overlegplatform geestelijke gezondheidszorg (PopovGGZ) en alle betrokken voorzieningen – geïnvesteerd in zorgvernieuwing, coördinatie en afstemming van de zorg in de drughulpverlening. Dit heeft naast heel wat ‘onzichtbare’ realisaties (bv. grotere bekendheid van het zorgaanbod, de intakeprocedure en werkwijze van andere voorzieningen, betere samenwerking tussen voorzieningen als gevolg van meer (informele) contactmomenten), ook tot een aantal duidelijk tastbare resultaten geleid. Het betreft onder meer de oprichting van een netwerkcomité middelenmisbruik, de aanstelling van een zorgcoördinator, de uitbouw van een case managementteam en de organisatie van een driewekelijks cliëntenoverleg. Met name deze laatste twee realisaties komen in voorliggend onderzoeksrapport uitgebreid aan bod. We doen dit in de eerste plaats door de direct betrokkenen (cliënten, hulpverleners en verantwoordelijken) zelf aan het woord te laten. De bevindingen van onze kwalitatieve evaluatie worden afzonderlijk besproken met betrekking tot het cliëntenoverleg en case management. Vooreerst worden beide werkvormen beschreven en worden enkele cijfergegevens meegegeven over de interventie in kwestie. Daarna volgt een beknopte bespreking van de gevolgde methodologie. Bij de rapportage van de onderzoeksresultaten wordt een onderscheid gemaakt tussen de bevindingen van hulpverleners over het cliëntenoverleg, de visie van cliënten over case management en het perspectief van case managers en projectverantwoordelijken over deze laatste interventie. We sluiten af met een aantal globale conclusies en aanbevelingen voor de toekomstige praktijk, die we terugbrachten tot tien concrete suggesties ter optimalisatie van het cliëntenoverleg en het case management. In tegenstelling tot eerdere publicaties beroepen we ons in dit onderzoeksrapport slechts in beperkte mate op de literatuur. In voorliggend rapport wilden we vooral het ‘insider’-perspectief laten primeren en voor meer theoretische beschouwingen verwijzen we dan ook naar eerdere publicaties (cf. Vanderplasschen, 2004)

    Role of low-ll component in deformed wave functions near the continuum threshold

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    The structure of deformed single-particle wave functions in the vicinity of zero energy limit is studied using a schematic model with a quadrupole deformed finite square-well potential. For this purpose, we expand the single-particle wave functions in multipoles and seek for the bound state and the Gamow resonance solutions. We find that, for the Kπ=0+K^{\pi}=0^{+} states, where KK is the zz-component of the orbital angular momentum, the probability of each multipole components in the deformed wave function is connected between the negative energy and the positive energy regions asymptotically, although it has a discontinuity around the threshold. This implies that the Kπ=0+K^{\pi}=0^{+} resonant level exists physically unless the l=0l=0 component is inherently large when extrapolated to the well bound region. The dependence of the multipole components on deformation is also discussed

    Embedding First-Order Tableaux into a Pure Type System

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    AbstractWe consider Pure Type Systems (PTSs) extended with a mechanism for parametric terms. In this paper we introduce a PTS called λP— utilizing this extension. λP— exactly corresponds to first-order predicate logic, unlike the usual embedding of this logic in PTSs. Next, we show how tableaux-based proofs can, in a structured way, be converted into λ-terms representing proofs in λP—. The result is an interactive theorem prover combined with powerful tableaux-based automatic proof construction

    International value chains : opportunities and challenges for small and developing countries

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    While internationalisation can improve firm performance, it is often only the most productive firms that are able to internationalise (Wagner, 2005, 2012; Melitz, 2003). Recent reductions in transportation costs and trade barriers alongside technological advances have fragmented production into intermediate tasks that can be executed in several countries, creating international value chains (IVCs). These IVCs can act as a stepping stone for less productive firms to tap into international markets, and benefit from learning-by-doing, without taking on all the tasks in the value chain, thereby lowering the entry requirements for internationalisation associated with exports (OECD, 2008). This article examines the opportunities and challenges of IVCs for SMEs in small and developing countries and, in a final section, applies some of these lessons to Scotland

    Imaging surface plasmon resonance for multiplex microassay sensing of mycotoxins

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    A prototype imaging surface plasmon resonance-based multiplex microimmunoassay for mycotoxins is described. A microarray of mycotoxin–protein conjugates was fabricated using a continuous flow microspotter device. A competitive inhibition immunoassay format was developed for the simultaneous detection of deoxynivalenol (DON) and zearalenone (ZEN), using a single sensor chip. Initial in-house validation showed limits of detection of 21 and 17 ng/mL for DON and 16 and 10 ng/mL for ZEN in extracts, which corresponds to 84 and 68 µg/kg for DON and 64 and 40 µg/kg for ZEN in maize and wheat samples, respectively. Finally, the results were critically compared with data obtained from liquid chromatography-mass spectrometry confirmatory analysis method and found to be in good agreement. The described multiplex immunoassay for the rapid screening of several mycotoxins meets European Union regulatory limits and represents a robust platform for mycotoxin analysis in food and feed sample
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