4 résultat(s) recherche sur le tag ''Réparation'

Aligned discontinuous fiber-based formable textiles for aircraft composite repair / E. Harris in SAMPE JOURNAL, Vol. 46, N° 3 (05-06/2010)

[article]  inSAMPE JOURNAL > Vol. 46, N° 3 (05-06/2010) . - p. 16-25 Titre : Aligned discontinuous fiber-based formable textiles for aircraft composite repair Type de document : texte imprimé Auteurs : E. Harris, Auteur ; Z. Olshenske, Auteur Année de publication : 2010 Article en page(s) : p. 16-25 Note générale : Bibliogr. Langues : Américain (ame) Tags : 'Industrie  aéronautique'  Avions  'Matériaux  composites  stratifiés'  'Textiles  à  usages  techniques'  'Réparation  par  collage'  'textile  DiscoTex®' Index. décimale : 677.4 Textiles artificiels Résumé : Lightweight, polymer matrix composites (PMC's) are an enabling material for Naval aircraft providing a combination of high stiffness to weight ratio and improved corrosion and fatigue resistance. In service Navy aircraft which incorporate extensive composite structure, though, are often subject to impact related damage resulting in various defects in the components which need to be repaired. Bonded patch repair processes are a preferred field repair solution (versus bolted repairs) as the resulting repair joint can obtain the stiffness and strength of the original part skin if performed correctly. Obtaining quality bonded repair joints becomes increasingly difficult, though, as the complex curvature of the part increases, even when using wet layup, fabric based laminate patches. This preliminary study evaluates the benefits of utilizing a new aligned, discontinuous "formable" textile called DiscoTex® (in development by Pepin Associates) for producing laminate patches for bonded repairs on select double curvature composite shapes typical of those geometries found on fixed wing fighter aircraft. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=9331 [article]

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Environmental and time dependence of moisture transportation in an epoxy coating and its significance for accelerated weathering / Shi Xiaodong in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 7, N° 4 (07/2010)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 7, N° 4 (07/2010) . - p. 419-430 Titre : Environmental and time dependence of moisture transportation in an epoxy coating and its significance for accelerated weathering Type de document : texte imprimé Auteurs : Shi Xiaodong, Auteur ; Brian R. Hinderliter, Auteur ; Stuart G. Croll, Auteur Année de publication : 2010 Article en page(s) : p. 419-430 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Epoxydes Revêtements -- Détérioration Revêtements -- Effets de l'humidité Revêtements:Peinture Tags : 'Revêtement  Epoxyde'  Détérioration  'Coefficient  de  diffusion'  'Cycle  température'  'Détérioration  accélérée'  'Transport  eau/humidité'  'Réparation  défauts' Index. décimale : 667.9 Revêtements et enduits Résumé : It is increasingly appreciated that water is one of the most important factors in the durability behavior of coatings. The rate of water transportation and the degree of saturation of polymeric coatings depends on exposure history, exposure environment, and the nature of a coating. The focus here is on the time taken for transport of water and the variation it causes in thermal and mechanical properties, which have also been shown previously to have time-dependence that leads to discrepancies between different weathering regimes. This paper studied the effect of moisture on coatings’ mechanical properties and the effect of moisture and temperature on recovery of surface indentation. The reduction of mechanical properties and the increasing rate of surface defect relaxation can be explained in terms of plasticization by water. Recovery of surface defects is related to the appearance and diffusion activity of coatings during exposure. Thermogravimetric analysis showed that the content of moisture in the sample is determined by the ambient humidity, temperature, and the rate of change in these environmental parameters. Diffusion coefficients were determined from the weight change data and an activation energy was obtained via Arrhenius equation. Changes in yellowness, as an example, and signature of chemical degradation, indicated that the cycling period in accelerated weathering may affect the degradation via the amount and distribution of moisture in coatings. Diffusion of moisture is typically slow and limits the possibility of complete drying or saturation in an exposure cycle. Results from the cumulative effect of many cycles will be different depending on the conditions DOI : 10.1007/s11998-009-9209-x En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-009-9209-x.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=9764 [article]

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N-palmitoyl-4-hydroxy-L-proline palmityl ester : A pseudoceramide that provides efficient skin barrier repair and protection / Gabriele Vielhaber in IFSCC MAGAZINE, Vol. 8, N° 3 (07-08-09/2005)

[article]  inIFSCC MAGAZINE > Vol. 8, N° 3 (07-08-09/2005) . - p. 185-190 Titre : N-palmitoyl-4-hydroxy-L-proline palmityl ester : A pseudoceramide that provides efficient skin barrier repair and protection Type de document : texte imprimé Auteurs : Gabriele Vielhaber, Auteur ; Sabine Lange, Auteur ; Jakob Ley, Auteur ; Oskar Koch, Auteur Année de publication : 2005 Article en page(s) : p. 185-190 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Céramides Un céramide est un sphingolipide résultant de la combinaison d'un acide gras avec la sphingosine via une liaison amide. On trouve de telles molécules en abondance dans les membranes cellulaires, où elles entrent notamment dans la constitution des sphingomyélines. Les céramides ne jouent pas qu'un rôle structurel dans les membranes biologiques, et peuvent également revêtir des fonctions de signalisation lipidique. Leurs actions les mieux comprises vont de la différenciation cellulaire à la mort cellulaire programmée (apoptose) en passant par la prolifération cellulaire. Les acides gras qui les constituent ont généralement un nombre pair (de 16 à 24) d'atomes de carbone, sont saturés ou monoinsaturés, et sont souvent α-hydroxylés. La plupart des céramides n'existent pas à l'état naturel si ce n'est comme précurseurs de la biosynthèse des sphingolipides par une réaction d'addition sur la fonction alcool primaire de la sphingosine. (Wikipedia) Palmitoyle Peau -- Soins et hygiène Tags : 'Réparation  de  la  barrière  l'épiderme'  Pseudocéramide  Céramide  'Dommage  SDS'  '(-)-a-bisabolol' Index. décimale : 668.5 Parfums et cosmétiques Résumé : Ceramides are the main constituents of the epidermal permeability barrier, and it has been demonstrated that the application of ceramide enriched creams promotes epidermal barrier repair. However, nature-identical ceramides are extremely expensive and difficult to formulate. We therefore developed a new pseudoceramide, N-palmitoyl-4-hydroxy-l-proline palmityl ester (BIO391). Due to its low melting point of £60°C the pseudoceramide BIO391 can easily be incorporated into cosmetic formulations. In addition, it is very safe for use in cosmetics. The efficacy of the pseudoceramide BIO391 was investigated in vivo in a model for detergent-induced barrier disruption. Trans-epidermal water loss, redness, and skin hydration were recorded before and after barrier disruption as well as during the subsequent 9-day treatment with the test products. Barrier repair of skin treated with the pseudoceramide BIO391 was accomplished earlier than that of untreated and vehicle treated skin. Optimum barrier repair was achieved with 1.0% pseudoceramide BIO391 and optimum erythema reduction with 0.5% pseudoceramide BIO391. The optimum dosage could be reduced to 0.1% pseudo-ceramide by synergistic combination with 0.1% (-)-a-bisabolol. In addition, the pseudoceramide BIO391 proved to be as effective as nature-identical ceramides 2 and 3. In summary, N-palmitoyl-4-hydroxy-l-proline palmityl ester is a highly efficient barrier repair agent with efficacy equivalent to that of nature-identical ceramides, and it has excellent formulation properties. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10493 [article]

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Prevention of UV-induced skin damage by activation of tumor suppressor genes p53 and p14ARF / Rolf-Dieter Petersen in IFSCC MAGAZINE, Vol. 6, N° 4 (10-11-12/2003)

[article]  inIFSCC MAGAZINE > Vol. 6, N° 4 (10-11-12/2003) . - p. 309-315 Titre : Prevention of UV-induced skin damage by activation of tumor suppressor genes p53 and p14ARF Type de document : texte imprimé Auteurs : Rolf-Dieter Petersen, Auteur ; John Sabrina, Auteur ; Maria Lueder, Auteur ; Stefan Borchert, Auteur Année de publication : 2003 Article en page(s) : p. 309-315 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Réparation  de  l'ADN'  'Vieillissement  prématuré'  'Suppression  des  gênes  tumoraux'  'Exposition  aux  UV'  'Protection Index. décimale : 668.5 Parfums et cosmétiques Résumé : UV-irradiated keratinocytes, pretreated with a soy seed-derived cosmetic active, showed a distinctly reduced decrease in ATP levels, a more effective DNA repair and a reduced formation of irreparable sunburn cells. The search for regulating mechanisms responsible for the results obtained suggested the investigation of the influence of this soy seed active on the tumor suppressor gene p53. Using primary human keratinocytes that were chronically UV-irradiated, it was possible to prove that the soy seed active significantly increased the p53 phosphorylation rate. Only phosphorylated p53, which acts as a transcription factor, can arrest the cell cycle in the case of DNA damage and up-regulated DNA repair or prevent survival of non-reparable cells by inducing apoptosis. In the same cell line it was found that, after chronic UV-irradiation, the soy seed active had stimulated the expression of the tumor suppressor gene p14ARF by more than twice the control rate. The significance of p14ARF for the functioning of the p53 pathway was recognized only recently. p53 can be down-regulated even in case of severe DNA damage without cell cycle arrest. The responsible factor is the p53 antagonist, the oncoprotein Mdm2. p14ARF as an inhibitor of Mdm2 can subsequently activate p53 and is therefore considered a second defense line in counteracting mutation. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10556 [article]

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