266 research outputs found

    Homoleptic imidazolate frameworks (3)(infinity)[Sr1-xEux(Im)(2)]-hybrid materials with efficient and tuneable luminescence.

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    Homoleptic frameworks of the formula 3āˆž[Sr1āˆ’xEux(Im)2] (1) x = 0.01ā€“1.0; Imāˆ’ = imidazolate anion, C3H3N2āˆ’) are hybrid materials that exhibit an intensive green luminescence. Tuning of both emission wavelength and quantum yield is achieved by europium/strontium substitution so that a QE of 80% is reached at a Eu content of 5%. Even 100% pure europium imidazolate still shows 60% absolute quantum efficiency. Substitution of Sr/Eu shows that doping with metal cations can also be utilized for coordination compounds to optimize materials properties. The emission is finely tuneable in the region 495ā€“508 nm via variation of the europium content. The series of frameworks 3āˆž[Sr1āˆ’xEux(Im)2] presents dense MOFs with the highest quantum yields reported for MOFs so far

    Microsystem in LTCC technology for measurements of gas concentration in a sub-ppm range

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    Commonly used substrates for resistance-type oxide sensors are mainly alumina plates. Other types of ceramics, e.g. based on Low Temperature Cofired Ceramics (LTCC) technology could also be used for this purpose. This technology is well established and enables a creation of 3D structures with channels and cavities that can be formed inside a LTCC micromodule. The work describes manufacturing of the microsystem containing a gas preconcentration chamber and sensor substrates with improved thermal properties, all fabricated in LTCC technology

    Intestinal Colonization of IL-2 Deficient Mice with Non-Colitogenic B. vulgatus Prevents DC Maturation and T-Cell Polarization

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    BACKGROUND: IL-2 deficient (IL-2(-/-)) mice mono-colonized with E. coli mpk develop colitis whereas IL-2(-/-)-mice mono-colonized with B. vulgatus mpk do not and are even protected from E. coli mpk induced colitis. METHODOLOGY/PRINCIPAL FINDINGS: We investigated if mono-colonization with E. coli mpk or B. vulgatus mpk differentially modulates distribution, activation and maturation of intestinal lamina propria (LP) dendritic cells (DC). LP DC in mice mono-colonized with protective B. vulgatus mpk or co-colonized with E. coli mpk/B. vulgatus mpk featured a semi-mature LP DC phenotype (CD40(lo)CD80(lo)MHC-II(hi)) whereas mono-colonization with colitogenic E. coli mpk induced LP DC activation and maturation prior to onset of colitis. Accordingly, chemokine receptor (CCR) 7 surface expression was more strikingly enhanced in mesenteric lymph node DC from E. coli mpk than B. vulgatus mpk mono- or co-colonized mice. Mature but not semi-mature LP DC promoted Th1 polarization. As B. vulgatus mpk promotes differentiation of semi-mature DC presumably by IL-6, mRNA and protein expression of IL-6 was investigated in LP DC. The data demonstrated that IL-6 mRNA and protein was increased in LP DC of B. vulgatus mpk as compared to E. coli mpk mono-colonized IL-2(-/-)-mice. The B. vulgatus mpk mediated suppression of CCR7 expression and DC migration was abolished in IL-6(-/-)-DC in vitro. CONCLUSIONS/SIGNIFICANCE: From this data we conclude that the B. vulgatus triggered IL-6 secretion by LP DC in absence of proinflammatory cytokines such as IL-12 or TNF-alpha induces a semi-mature LP DC phenotype, which might prevent T-cell activation and thereby the induction of colitis in IL-2(-/-)-mice. The data provide new evidence that IL-6 might act as an immune regulatory cytokine in the mucosa by targeting intestinal DC

    On numerical relativistic hydrodynamics and barotropic equations of state

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    The characteristic formulation of the relativistic hydrodynamic equations (Donat et al 1998 J. Comput. Phys. 146 58), which has been implemented in many relativistic hydro-codes that make use of Godunov-type methods, has to be slightly modified in the case of evolving barotropic flows. For a barotropic equation of state, a removable singularity appears in one of the eigenvectors. The singularity can be avoided by means of a simple renormalization which makes the system of eigenvectors well defined and complete. An alternative strategy for the particular case of barotropic flows is discussed.Comment: 7 pages, no figures. Accepted for publication in Class. Quantum Gra

    Novel mutations in the VKORC1 gene of wild rats and mice ā€“ a response to 50 years of selection pressure by warfarin?

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    <p>Abstract</p> <p>Background</p> <p>Coumarin derivatives have been in world-wide use for rodent pest control for more than 50 years. Due to their retarded action as inhibitors of blood coagulation by repression of the vitamin K reductase (VKOR) activity, they are the rodenticides of choice against several species. Resistance to these compounds has been reported for rodent populations from many countries around the world and poses a considerable problem for efficacy of pest control.</p> <p>Results</p> <p>In the present study, we have sequenced the <it>VKORC1 </it>genes of more than 250 rats and mice trapped in anticoagulant-exposed areas from four continents, and identified 18 novel and five published missense mutations, as well as eight neutral sequence variants, in a total of 178 animals. Mutagenesis in <it>VKORC1 </it>cDNA constructs and their recombinant expression revealed that these mutations reduced VKOR activities as compared to the wild-type protein. However, the <it>in vitro </it>enzyme assay used was not suited to convincingly demonstrate the warfarin resistance of all mutant proteins</p> <p>Conclusion</p> <p>Our results corroborate the <it>VKORC1 </it>gene as the main target for spontaneous mutations conferring warfarin resistance. The mechanism(s) of how mutations in the <it>VKORC1 </it>gene mediate insensitivity to coumarins <it>in vivo </it>has still to be elucidated.</p

    Defining elite athletes: Issues in the study of expert performance in sport psychology

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    Ā© 2014 Elsevier Ltd. Objectives: There has been considerable inconsistency and confusion in the definition of elite/expert athletes in sport psychology research, which has implications for studies conducted in this area and for the field as a whole. This study aimed to: (i) critically evaluate the ways in which recent research in sport psychology has defined elite/expert athletes; (ii) explore the rationale for using such athletes; and (iii) evaluate the conclusions that research in this field draws about the nature of expertise. Design: Conventional systematic review principles were employed to conduct a rigorous search and synthesise findings. Methods: A comprehensive literature search of SPORTDiscus, Academic Search Complete, PsycINFO, and PsycARTICLES was completed in September, 2013 which yielded 91 empirical studies published between 2010 and 2013. The primarily qualitative findings were analysed thematically. Results: Eight ways of defining elite/expert athletes were identified, ranging from Olympic champions to regional level competitors and those with as little as two years of experience in their sport. Three types of rationale were evident in these studies (i.e., "necessity", "exploratory" and "superior"); while findings also indicated that some elite athletes are psychologically idiosyncratic and perhaps even dysfunctional in their behaviour. Finally, only 19 of the 91 included studies provided conclusions about the nature of expertise in sport. Conclusions: This study suggests that the definitions of elite athletes vary on a continuum of validity, and the findings are translated into a taxonomy for classifying expert samples in sport psychology research in future. Recommendations are provided for researchers in this area

    Light emitting diodes (LEDs) applied to microalgal production.

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    Light-emitting diodes (LEDs) will become one of the world's most important light sources and their integration in microalgal production systems (photobioreactors) needs to be considered. LEDs can improve the quality and quantity of microalgal biomass when applied during specific growth phases. However, microalgae need a balanced mix of wavelengths for normal growth, and respond to light differently according to the pigments acquired or lost during their evolutionary history. This review highlights recently published results on the effect of LEDs on microalgal physiology and biochemistry and how this knowledge can be applied in selecting different LEDs with specific technical properties for regulating biomass production by microalgae belonging to diverse taxonomic groups
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