602 resultados para Blowing


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The characteristics of sharkskin surface instability for linear low density polyethylene are studied as a function of film blowing processing conditions. By means of scanning electron microscopy and surface profilometry, is it found that for the standard industrial die geometry studied, sharkskin only occurs on the inside of the film bubble. Previous work suggests that this instability may be due to critical extensional stress levels at the exit of the die. Isothermal integral viscoelastic simulations of the annular extrusion process are reported, and confirm that the extensional stress at the die exit is large enough to cause local melt rupture. However the extensional stress level at the outer die wall predicts melt rupture of the outside bubble surface also, which contradicts the experimental findings. A significant temperature gradient is expected to exist across the die gap at the exit of the die, due to the external heating of the die and the low conductivity, of the polymer melt. It is shown that a gradient of 20 degreesC is required to cause sharkskin to only appear on the inner bubble surface.

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Citric acid was used as a compatibilizer in the production of starch and PBAT films plasticized with glycerol and processed by blow extrusion. Films produced were characterized by WVP, mechanical properties, FT-IR-ATR and SEM. WPV ranged from 3.71 to 12.73×10-11 g m-1 s-1 Pa-1, while tensile strength and elongation at break ranged from 1.81 to 7.15 MPa and from 8.61 to 23.63%, respectively. Increasing the citric acid concentration improved WVP and slightly decreased film resistance and elongation. The films micrographs revealed a more homogeneous material with the addition of citric acid. However, the infrared spectra revealed little about cross-linking esterification reaction

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Auditing is often cited as playing an important role in managing agency-related costs and, accordingly, being integral to the sound functioning of capital markets. There may, however, be more to the attest function than a technical rational practice. By virtue of relying heavily on claims to technical expertise, professionalism, prudential judgement and public confidence, auditing is both a source of legitimacy for organisations and, paradoxically, dependent on claims to legitimacy for its continued existence. From this perspective, recent regulatory developments, purportedly enacted to increase arms-length control over the profession, may not only be about improving perceived audit quality and practice but also about ensuring continued faith in the well-established ‘rituals’ of the assurance function. A reporting duty imposed on South African external auditors, akin to whistle-blowing, is used as a case study to explore this perspective. In doing so, this paper contributes to the scant body of interpretive research on auditing, simultaneously offering one of the first insights into auditing regulation from an African perspective.

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When the solar wind blows: The northern lights are a sign of the awesome power that the Earth receives from the solar wind. The big puzzle is how

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This study examines the effects of the source of whistle-blowing allegations and potential for allegations to trigger concerns about reputation threats on Chief Audit Executives’ handling of whistle-blowing allegations. The participants for this study, 79 Chief Audit Executives (CAEs) and deputy CAEs, evaluated whistle-blowing reports related to financial reporting malfeasance that were received from either an anonymous or a non-anonymous source. The whistle-blowing reports alleged that the wrongdoing resulted from either the exploitation of substantial weaknesses in internal controls (suggesting higher responsibility of the CAE and internal audit) or the circumvention of internal controls (suggesting lower responsibility of the CAE or internal audit). Findings indicate that CAEs believe anonymous whistle-blowing reports to be significantly less credible than non-anonymous reports. Although CAEs assessed lower credibility ratings for the reports alleging wrongdoing by the exploitation of substantial weaknesses in internal controls, they allocated more resources to investigating these allegations.

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Metakaolin and volcanic ashes respectively called MK and ZG were used as aluminosilicate raw materials for the synthesis of porous geopolymers. The hydrogen peroxide was used as a blowing agent. The geopolymer prepared were characterized by Spectroscopy Fourier Transform Infrared (SFTI), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and the determination of some physical properties such as bulk density, total porosity, volume shrinkage, compressive strength and thermal conductivity was also carried out. The presence of pores in the geopolymer obtained is function of the percentage of hydrogen peroxide added, causing the concomitantly decrease in compressive strength, apparent density and thermal conductivity. The use of hydrogen peroxide as a blowing agent gave some thermal insulation properties to these geopolymers which could be close to the properties of some commercial insulation materials.

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"October 1995."

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on verso: "All I got out of this effort to "toot" this horn was a bunch of wrinkles on my face."

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"Reprinted from 'The outlook', Nov. 18th, 1914."

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The author elaborates some issues raised in the theoretical basis of whistleblowing put forward by Faunce. The author considers the relationship between bioethics teaching and professional behaviour and the role of principlism in teaching bioethics and medical ethics.