16,711 research outputs found

    Synthesis and characterization of silver nanoarticles from extract of Eucalyptus citriodora

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    The primary motivation for the study to develop simple eco-friendly green synthesis of silver nanoparticles using leaf extract of Eucalyptus citriodora as reducing and capping agent. The green synthesis process was quite fast and silver nanoparticles were formed within 0.5 h. The synthesis of the particles was observed by UV-visible spectroscopy by noting increase in absorbance. Characterization of the particles was carried out by X-ray diffraction, FTIR and electron microscopy. The developed nanoparticles demonstrated that E. citriodora is good source of reducing agents. UV-visible absorption spectra of the reaction medium containing silver nanoparticles showed maximum absorbance at 460 nm. FTIR analysis confirmed reduction of Ag+ to Ag0 atom in silver nanoparticles. The XRD pattern revealed the crystalline structure of silver nanoparticles. The SEM analysis showed the size and shape of the nanoparticles. The method being green, fast, easy and cost effective can be recommended for large scale production of AgNPs for their use in food, medicine and materials

    Examining the effects of celebrity trust on advertising credibility, brand credibility, and corporate credibility

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    Drawing on signalling theory, this study aims to fill a gap in knowledge by examining the effects of celebrity trust on advertising credibility, brand credibility and corporate credibility, both directly and based on the moderating variables of age, gender and ethnicity. The research has three objectives: (i) to explore the effects of celebrity trust on advertising credibility, brand credibility and corporate credibility; (ii) to explore the effects of celebrity trust on advertising credibility, brand credibility and corporate credibility, based on the moderating effects of consumer demographics; and (iii) to explore the effects of the other constructs on each other, i.e. advertising credibility on brand credibility and corporate credibility, and brand credibility on corporate credibility. For this purpose, a survey of 625 respondents was conducted in London. The empirical results show that celebrity trust has a positive effect on both advertising credibility and brand credibility, and that these effects are moderated by consumers’ ethnicity, with no obvious effects of age or gender. No effect was found on corporate credibility. The effects of advertising credibility on brand credibility and corporate credibility, and of brand credibility on corporate credibility, were found to be significant. The significant implications for managers and researchers are highlighted

    Examining the effects of advertising credibility on brand credibility, corporate credibility and corporate image: a qualitative approach

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    Purpose – The aim of this study is to understand the concept of advertising credibility and examine its effects on brand credibility, corporate credibility and corporate image. Design/methodology/approach – A qualitative approach was used. Ten interviews and four mini focus groups were conducted among participants drawn from the 32 London boroughs. Data was analysed by using thematic analysis. Findings - The findings suggest that advertising credibility is defined using terms like accurate, caring, competent, complete, convincing, ethical, honest, impressive, reliable and warranted; and on the basis that it delivers what it promises about the products/service. The findings also suggest that advertising credibility has a positive effect on brand credibility, corporate credibility and corporate image. Originality/value – Advertising credibility has received little attention in the literature. This is the first study, which has exploratory examined its effects on brand credibility, corporate credibility, and corporate image

    Current AATS guidelines on surgical treatment of infective endocarditis

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    © Annals of Cardiothoracic Surgery. The 2016 American Association for Thoracic Surgery (AATS) guidelines for surgical treatment of infective endocarditis (IE) are question based and address questions of specific relevance to cardiac surgeons. Clinical scenarios in IE are often complex, requiring prompt diagnosis, early institution of antibiotics, and decision-making related to complications, including risk of embolism and timing of surgery when indicated. The importance of an early, multispecialty team approach to patients with IE is emphasized. Management issues are divided into groups of questions related to indications for and timing of surgery, pre-surgical work-up, preoperative antibiotic treatment, surgical risk assessment, intraoperative management, surgical management, surveillance, and follow up. Standard indications for surgery are severe heart failure, severe valve dysfunction, prosthetic valve infection, invasion beyond the valve leaflets, recurrent systemic embolization, large mobile vegetations, or persistent sepsis despite adequate antibiotic therapy for more than 5-7 days. The guidelines emphasize that once an indication for surgery is established, the operation should be performed as soon as possible. Timing of surgery in patients with strokes and neurologic deficits require close collaboration with neurological services. In surgery infected and necrotic tissue and foreign material is radically debrided and removed. Valve repair is performed whenever possible, particularly for the mitral and tricuspid valves. When simple valve replacement is required, choice of valve-mechanical or tissue prosthesis-should be based on normal criteria for valve replacement. For patients with invasive disease and destruction, reconstruction should depend on the involved valve, severity of destruction, and available options for cardiac reconstruction. For the aortic valve, use of allograft is still favored

    Underlying Fermi surface of Sr14x_{14-x}Cax_xCu24_{24}O41_{41} in two-dimensional momentum space observed by angle-resolved photoemission spectroscopy

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    We have performed an angle-resolved photoemission study of the two-leg ladder system Sr14x_{14-x}Cax_xCu24_{24}O41_{41} with xx= 0 and 11. "Underlying Fermi surfaces" determined from low energy spectral weight mapping indicates the quasi-one dimensional nature of the electronic structure. Energy gap caused by the charge density wave has been observed for xx=0 and the gap tends to close with Ca substitution. The absence of a quasi-particle peak even in xx=11 is in contrast to the two-dimensional high-TcT_c cuprates, implying strong carrier localization related to the hole crystalization.Comment: 5 pages, 3 figure

    Modelling Knudsen number effects in suspension high velocity oxy fuel thermal spray

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    Suspension high velocity oxy fuel thermal spray is a system characterized by supersonic velocities and length scales of particles of the order of nm – µm. As the effects of rarefication become significant the assumptions within the continuum models begin to collapse, the effects of rarefication can be evaluated through the flow Knudsen number. Modifications to the numerical modelling must be made to incorporate the effects of rarefaction. This study looks to include the effects of rarefication into the computational fluid dynamics (CFD) models for the suspension high velocity oxy-fuel (SHVOF) thermal spray process. A model for the heat transfer coefficient that take into account the Knudsen and Mach number effects is employed. Finally, the Ranz-Marshall correlation for the Nusselt number is compared to the Kavanau correlation and a compressible Nusselt number correlation. The model is validated through comparisons of particle temperatures which are obtained from two colour pyrometry measurements using a commercially available Accuraspray 4.0 diagnostic system. This study shows that there is a significant improvement in the prediction of inflight particle temperatures when accounting for the effects of compressibility and the effects of rarefication on the Nusselt number

    ARPES studies of cuprate Fermiology: superconductivity, pseudogap, and quasiparticle dynamics

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    We present angle-resolved photoemission spectroscopy (ARPES) studies of the cuprate high-temperature superconductors which elucidate the relation between superconductivity and the pseudogap and highlight low-energy quasiparticle dynamics in the superconducting state. Our experiments suggest that the pseudogap and superconducting gap represent distinct states, which coexist below Tc_c. Studies on Bi-2212 demonstrate that the near-nodal and near-antinodal regions behave differently as a function of temperature and doping, implying that different orders dominate in different momentum-space regions. However, the ubiquity of sharp quasiparticles all around the Fermi surface in Bi-2212 indicates that superconductivity extends into the momentum-space region dominated by the pseudogap, revealing subtlety in this dichotomy. In Bi-2201, the temperature dependence of antinodal spectra reveals particle-hole asymmetry and anomalous spectral broadening, which may constrain the explanation for the pseudogap. Recognizing that electron-boson coupling is an important aspect of cuprate physics, we close with a discussion of the multiple 'kinks' in the nodal dispersion. Understanding these may be important to establishing which excitations are important to superconductivity.Comment: To appear in a focus issue on 'Fermiology of Cuprates' in New Journal of Physic

    Polaronic behavior of undoped high-Tc cuprates

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    We present angle-resolved photoemission spectroscopy (ARPES) data on undoped La2CuO4, indicating polaronic coupling between bosons and charge carriers. Using a shell model, we calculate the electron-phonon coupling and find that it is strong enough to give polarons. We develop an efficient method for calculating ARPES spectra in undoped systems. Using the calculated couplings, we find the width of the phonon side band in good agreement with experiment. We analyze reasons for the observed dependence of the width on the binding energy.Comment: 4 pages, RevTeX, 5 eps figures, more material available at http://www.fkf.mpg.de/andersen/phonons
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