198,855 research outputs found
A non-invasive capacitive sensor strip for aerodynamic pressure measurement
No full textThis paper presents a capacitive pressure sensor strip implemented in general purpose printed circuit board (PCB) technology based on a thin 3D structure composed of polyimide, woven glass reinforced epoxy resin (FR4) and metal layers. Multiphysics finite elements method (FEM) simulations have been performed over the proposed structure in order to develop a time-dependent electrical and mechanical model that can be easily used to tailor the characteristics to the application. The device targets a wide class of fluid dynamics applications, being non-invasive, comformable and smart for placement. The device simulations are herein validated by experimental wind tunnel measurements and compared with figures obtained on a wing profile by conventional electromechanical pressure transducers. This approach is one of the first example of fully embedding and electronically controlled fluid flow monitoring apparatus that could be used in replacement of state of the art mechanical systems
Ormetica bonora
No full text<i>Ormetica bonora</i> (Schaus, 1905) <p> <i>Automolis bonora</i> Schaus, 1905: 219.</p> <p> <i>Ormetica bonora</i> – Watson 1971: 17.</p> <p> <i>Automolis ochreomarginata</i> Joicey & Talbot, 1918: 267, n. syn.</p> <p> <i>Ormetica ochreomarginata</i> – Watson 1975: 84.</p> <p>ARGUMENTAIRE TAXONOMIQUE</p> <p> <i>Automolis bonora</i> Schaus, 1905 est décrit sur un mâle unique provenant de Cayenne. <i>Automolis ochreomarginata</i> Joicey &Talbot, 1918 est décrit sur un mâle unique provenant de Saint-Jean-du-Maroni en Guyane. Dans leur publication, Joicey & Talbot (1918) comparent leur nouvelle espèce uniquement à <i>Ormetica sicilia</i> Druce, 1884 d’Amérique centrale, visiblement n’ayant pas connaissance de <i>O. bonora</i>. Pourtant les deux espèces ont manifestement des habitus identiques. Nous proposons donc cette synonymie.</p>Published as part of <i>Vincent, Benoît & Laguerre, Michel, 2013, Changements nomenclaturaux chez les Arctiinae nÉotropicales (Insecta, Lepidoptera, Erebidae); seconde partie, pp. 425-455 in Zoosystema 35 (3)</i> on page 437, DOI: 10.5252/z2013n3a5, <a href="http://zenodo.org/record/5165260">http://zenodo.org/record/5165260</a>
It’s all about the surface! Vibrational spectroscopy applied to the study of biomimetic surfaces in Tissue Engineering
No full textTissue Engineering is a multidisciplinary field aimed at the creation of biological substitutes that restore and maintain the biological function of a damaged tissue. The key of the success of these biomedical devices lies into surface interactions with living tissues, therefore a common strategy is to create biomimetic surfaces that helps cells to colonize the biomaterial, leading to tissue healing.
Vibrational spectroscopy, in particular Raman, apart from being mainly surface and non-destructive technique, is extremely sensitive to changes in structure and molecular interactions, thus its use in investigating biomimetic devices is increasing.
In particular, we have recently used vibrational spectroscopies to investigate different biomimetic materials and to test some of their proprieties:
- self-assembling peptides adsorbed on titanium surfaces for bone implants [1], analyzed before and after attack from free radicals (obtained by gamma-radiolysis and mimicking inflammation processes) [2], with the aim to evaluate their capability in resisting to oxidative stress;
- composite (ceramic-polymer, polymer-polymer) bioresorbable biomaterials [3, 4];
- hydroxyapatite nanomaterials functionalized with proteins to increase biocompatibility [5-7].
[1] M. Di Foggia, P. Taddei, A. Torreggiani, M. Dettin, A. Tinti, J. Raman Spectrosc. 42 (2011) 276-285.
[2] M. Di Foggia, A. Torreggiani, P. Taddei, M. Dettin, A. Tinti, J. Raman Spectrosc. 44 (2013) 1446-1450.
[3] V. Guarino, F. Causa, P. Taddei, M. Di Foggia, G. Ciapetti, D. Martini, C. Fagnano, N. Baldini, L. Ambrosio, Biomaterials 29 (2008) 3662-3670.
[4] V. Guarino, P. Taddei, M. Di Foggia, C. Fagnano, G. Ciapetti, L. Ambrosio, Tissue Eng. A 15 (2009) 3655-3668.
[5] M. Iafisco, B. Palazzo, G. Falini, M. Di Foggia, S. Bonora, S. Nicolis, L. Casella, N. Roveri, Langmuir 24 (2008) 4924-4930.
[6] M. Iafisco, M. Di Foggia, S. Bonora, M. Prat, N. Roveri, Dalton Trans. 40 (2011) 820-827.
[7] M. Iafisco, E. Varoni, M. Di Foggia, S. Pietronave, M. Fini, N. Roveri, L. Rimondini, M. Prat, Colloids Surf.s B 90 (2012) 1-7
Hawking radiation, W-infinity algebra and trace anomalies
No full textWe apply the “trace anomaly method” to the calculation of moments of the Hawking radiation of a Schwarzschild black hole. We show that they can be explained as the fluxes of chiral currents forming a W∞ algebra. Then we construct the covariant version of these currents and verify that up to order 6 they are not affected by any trace anomaly. Using cohomological methods we show that actually, for the fourth order current, no trace
anomalies can exist. The results reported here are strictly valid in two dimensions
Superfield formulation of extended BRS symmetry
No full textIn the light of a recently discovered new BRS-like symmetry in gauge theories, we reformulate a superfield treatment of lagrangian gauge theories supplemented by gauge-fixing and Faddeev-Popov terms
A primary creep model for Class M materials
No full textIn many high temperature applications the accumulation of creep strain during the primary stage cannot be ignored since most of the allowable design strain occurs in this stage. An appropriate modelling is therefore needed. In this work, a mechanism based model for primary creep has been derived assuming that the creep rate in the transient regime can be given as a function of the steady state creep rate and the internal stress. Taking into account that the apparent activation energy varies with the internal stress and that the internal stress kinetics can be given as a function of strain, an exponential form of the creep rate versus creep strain has been obtained. The proposed model has been applied to high chromium steel P91 and René 80 nickel based superalloy. The decay constant and scaled activation volume have been found to vary only with the applied stress and not with temperature. The evolution of the these two parameters with stress seems to indicate the stress at which the transition from diffusional flow to dislocation climb creep occurs
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