Yazar "Dogan, A." seçeneğine göre listele

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    Effect of new punched vortex generators in a rectangular channel on heat transfer using Taguchi method
    (Taylor & Francis Inc, 2021) Caliskan, S.; Dogan, A.; Sahin, U. R.
    In this study, the effects of New Punched Rectangular Vortex Generators (NPRVGs) and Punched Rectangular Vortex Generators (PRVGs) inside a rectangular channel on heat transfer augmentation, Nusselt number, and friction factor were experimentally investigated. Temperature contours and average Nusselt numbers analyzed heat transfer characteristics resulting from the use of vortex generators. Furthermore, this study investigated the optimum values of the design parameters within the system of vortex generators by using the Taguchi method, and the orthogonal experimental plan was made for L-16 (4(3)x2(1)). Reynolds numbers (5181, 10363, 20328, 25510), winglet arrangement, winglet attack angles (15 degrees, 30 degrees, 45 degrees, 75 degrees) and a distance of punched winglet from the channel bottom (b) to constant winglet height (e = 25 mm) (b/e = 0.04, 0.12, 0.2 and 0.36) were determined the working parameters in the experiments. Measurements are carried out for a rectangular channel with aspect ratio AR = 2, winglet transverse pitch (S) to longitudinal winglet height (e) ratio of S/e = 0.67 and a winglet height (e) to channel height (H = 25 mm) ratio of e/H = 1. Heat transfer rates of NPRVGs and PRVGs were compared to the obtained results for a smooth channel. The heat transfer performance is improved considerably by the NPRVGs. The maximum thermal performance factor increased from 0.99 to 1.89 owing to the combination of the vortex generator and the newly punched hole.
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    Öğe
    The in vivo effects of Verbascum speciosum on wound healing
    (Elsevier Science Bv, 2018) Kayir, S.; Demirci, Y.; Demirci, S.; Erturk, E.; Ayaz, E.; Dogan, A.; Demirci, S.
    Wound healing is a well-orchestrated and tightly controlled process in which several cell types, cytokines and growth factor take place in an orderly fashion. Any break in the process would cause delay in healing which would increase hospitalization time, cost, mortality and morbidity. Scientists and clinicians are trying to find effective, safe and cheap methods to treat and manage acute and non-healing chronic wounds. Medicinal plants, in this line, have been widely investigated, and gained remarkable attention in this field due to having vital therapeutic molecules. In the current study, methanol extract of Verbascum speciosum leaves, collected in 2014 from Trabzon, Turkey, was integrated into a vaseline-based cream and tested on full-thickness wounds in vivo. The results revealed that 5% (w/v) and 10% (w/v) extract containing cream treated rats displayed significantly higher wound contraction compared to non-treated and base cream applied animals as evident by macroscopical analysis. However, no difference were found in histological examinations among the groups in terms of inflammatory cell infiltration, fibroblast density, collagen deposition and angiogenesis. Further studies are highly warranted in order to arrange dose and formulation of the plant extract and to understand the molecular mechanism for potential wound healing promoting activity. (C) 2018 SAAB. Published by Elsevier B.V. All rights reserved.