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Yield stress as measured in steady shearing and in oscillations / Irina Masalova in APPLIED RHEOLOGY, Vol. 18, N° 4 (2008)
[article]
Titre : Yield stress as measured in steady shearing and in oscillations Type de document : texte imprimé Auteurs : Irina Masalova, Auteur ; A. Ya. Malkin, Auteur ; Reza Foudazi, Auteur Année de publication : 2008 Article en page(s) : 8 p. Note générale : Bibliogr. Langues : Anglais (eng) Tags : Emulsions Suspensions Kaolin Mayonnaise 'Contrainte de rendement' 'Courbes d'écoulement' 'Balayage d'amplitude' Index. décimale : 532.05 Mécanique des fluides et des liquides - Dynamique (cinétique et cinématique) Résumé : La contrainte d’écoulement de cinq échantillons (deux émulsions à forte concentration, deux dispersions au
Kaolin et une mayonnaise) a été déterminée de deux façons. Dans un cas, les expériences de cisaillement continu ont été effectuées sur une gamme de taux de cisaillement décroissants. Les courbes d’écoulement résultantes, tracées comme contrainte de cisaillement par rapport au taux de cisaillement, montrent clairement l’existence d’une contrainte d’écoulement dans chaque échantillon, le modèle Herschel-Burkley ayant été utilisé pour obtenir les valeurs. Dans le second cas on a effectué un balayage d’amplitude oscillatoire sur trois fréquences, et la "contrainte dynamique d’écoulement" a été définie comme la contrainte à laquelle avait lieu la déviation de la linéarité ; cette procédure a souvent été utilisée pour déterminer la contrainte d’écoulement des émulsions. On a trouvé que la contrainte dynamique d’écoulement dépend de la fréquence, et par conséquent ne peut pas être considérée comme une propriété physiquement signifiante du matériel. Sous aucune fréquence la contrainte dynamique d’écoulement a été en corrélation avec la contrainte d’écoulement obtenue des courbes d’écoulement.Référence de l'article : 44790 DOI : 10.3933/ApplRheol-18-44790 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=26611
in APPLIED RHEOLOGY > Vol. 18, N° 4 (2008) . - 8 p.[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 010737 - Périodique Bibliothèque principale Documentaires Disponible Blackberry leaf extract : a multifunctional anti-aging active / Martina Herrmann in IFSCC MAGAZINE, Vol. 10, N° 1 (01-02/2007)
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Titre : Blackberry leaf extract : a multifunctional anti-aging active Type de document : texte imprimé Auteurs : Martina Herrmann, Auteur ; Susanne Grether-Beck, Auteur ; Imke Meyer, Auteur ; Helge Franke, Auteur ; Holger Joppe, Auteur ; Jean Krutmann, Auteur ; Gabriele Vielhaber, Auteur Année de publication : 2007 Article en page(s) : p. 41-45 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Extrait de feuille Blackberry' 'Balayage radical' 'Rubus fructicosus' 'Anti-âge' 'Mmp-1' 'Il-1?' Index. décimale : 668.5 Parfums et cosmétiques Résumé : Matrix metalloproteinases (MMPs) play a major role in wrinkle formation. Their expression increases with aging and is further enhanced by UV irradiation. Blackberry (Rubus fruticosus) leaf extract has been shown to suppress MMP-1, -2 and -9 in cell-free assays. We have now further explored the activity of this extract. The effect on MMP-1 expression at the protein and the mRNA level was investigated using non-irradiated and UVA-irradiated human dermal fibroblasts. The extract showed a dose-dependent reduction of the MMP-1 protein level of both irradiated and non-irradiated cells with an almost complete inhibition at a dosage of 0.1%. MMP-1 mRNA expression of UVA-irradiated cells was decreased after pre-incubation as well as after post-incubation with the extract. Best results were obtained with combined pre- and post-treatment (0.1% extract led to 59% reduction in comparison with the respective control). Moreover, we found that blackberry leaf extract inhibits IL-1α, a cytokine known to induce MMP expression. At a dosage of 0.2% the inhibition was 40% compared with that of the stimulated control. The extract also exhibited a potent radical scavenging activity comparable to that of α-tocopherol as was shown by the ABTS assay. Taken together, these biological activities make blackberry leaf extract a highly efficient multifunctional anti-aging active. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10428
in IFSCC MAGAZINE > Vol. 10, N° 1 (01-02/2007) . - p. 41-45[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 007646 - Périodique Bibliothèque principale Documentaires Disponible Determining rheological behaviour of paints, iks and coatings / Oliver Sack in POLYMERS PAINT COLOUR JOURNAL - PPCJ, Vol. 209, N° 4654 (09/2019)
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Titre : Determining rheological behaviour of paints, iks and coatings Type de document : texte imprimé Auteurs : Oliver Sack, Auteur ; Anton Paar, Auteur Année de publication : 2019 Article en page(s) : p. 20-21 Langues : Anglais (eng) Catégories : Encre
Revêtements organiques
Revêtements:Peinture
Rhéologie
RhéomètresTags : Rhéomètre 'Expériences de rotation' oscillatoires' 'Balayage d'amplitude' 'Décomposition structurelle' 'Reprise structurelle''Test temps à 3 intervalles' Index. décimale : 667.9 Revêtements et enduits Résumé : Understanding rheological properties of paints, inks and coatings is of great importance for many industrial applications, such as manufacturing, processing and curing/hardening.
Simple rotational experiments like shear stress-(CS) and shear rate (CR) controlled tests give only information about the viscosity value, the "seeming" yield point and the thixotropic effect. Since it is known for many years, that these values are not sufficient to describe the complex visco-elastic properties of paints, the use of more sensitive rheometers is recommended fora better understanding of the rheological characterisation. Modern air bearing-based rheometers provide the possibility to perform rotational tests, as well as oscillatory shear measurements. Measurements which are carried out under oscillatory shear conditions, provide advantages for characterising liquid and cured (film) paints and coatings. In addition, the curing or hardening process can be investigated and the glass transition point (Tg) can be determined. The most common used oscillatory experiments are the amplitude sweep (AS), frequency sweep (FS) and the structural recovery test (31TT). While the AS is used to determine the yield/flow point and the structural strength, the FS provides information about the sedimentation stability of the material. 31TT-tests are used to describe the levelling and sagging behaviour after the application process, as well as the thixotropic effect (time dependent structural recovery). Curing and hardening processes can not only be performed time and temperature controlled but also under UV exposure. For this reason, an air bearing-based rheometer is essential to avoid any shear influences to the 3-dimensional structures that corne up during the curing process. Compared to a viscometer, a modern rheometer system can be used fora full rheological characterisation of paints, inks and coatings.The generated data provide a deeper view inside the structure of the materials and help to understand and improve the manufacturing process and applicational problems.Note de contenu : - Rotational experiments - state of the art
- Oscillatory experiments - modern methods
- Structural decomposition and regeneration
- Fig. 1 : Silver 3 (organoclay), silver 1 (acrylic thickener) and silver 3 (polyurethane thickener)
- Fig. 2 : Shows the viscosity curves of the three different paints. Over the shear rate range between 0.1 to 10005-1 the samples show much higher viscosity values compared to lower shear rates
- Fig. 3 : Amplitude sweeps of the three different silver coatings
- Fig. 4 : 3-Interval-Time-Tests (3ITT) of three different silver coatingsEn ligne : https://drive.google.com/file/d/12NXSuASvepHIkB7w7qqmvK3o3ZKW9Sxy/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32917
in POLYMERS PAINT COLOUR JOURNAL - PPCJ > Vol. 209, N° 4654 (09/2019) . - p. 20-21[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 21175 - Périodique Bibliothèque principale Documentaires Disponible Flow stabilization and coating thickness reduction through use of multi-slot air-knife in gas jet wiping / J. R. McDermid ; Andrew N. Hrymak ; F. E. Goodwin in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 19, N° 1 (01/2022)
[article]
Titre : Flow stabilization and coating thickness reduction through use of multi-slot air-knife in gas jet wiping Type de document : texte imprimé Auteurs : J. R. McDermid, Auteur ; Andrew N. Hrymak, Auteur ; F. E. Goodwin, Auteur Année de publication : 2022 Article en page(s) : p. 143-158 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Fluides, Mécanique des
Galvanisation
Matériaux -- Epaisseur
RevêtementsTags : 'Balayage au jet de gaz' 'Réduction l'épaisseur du revêtement' 'Lame d'air multi-fentes' 'Galvanisation à chaud continue' 'Modélisation des turbulences' 'Mesures d'épaisseur Index. décimale : 667.9 Revêtements et enduits Résumé : This paper investigates the gas jet wiping process, which is widely employed for controlling the final zinc-alloy coating thickness of a moving steel strip in the continuous hot-dip galvanizing process. In this study, large eddy simulation (LES) was employed to determine the effect of lower velocity symmetric auxiliary jets on main jet stabilization and coating thickness reduction during the gas jet wiping process. For validation purposes, experimental measurements of coating thickness were also carried out for the prediction of final coating thickness via a novel prototype multi-slot air knife used as the wiping actuator. Good agreement was found between the experimental measurements and model predictions for the coating weight, which also confirmed the applicability of the Elsaadawy et al.1 model for the prediction of final coating weight for the multi-slot air knife geometry used. It was found that the jet flapping observed during single jet wiping could be prevented through use of the multi-slot air knife operating with lower velocity symmetric auxiliary jets (Rea/Rem = 0.45) situated on both sides of the main jet. The auxiliary jets modified the flow field in the main jet shear layer and diminished the formation of alternating vortices, which are the main cause of jet flow oscillations. As a result, a stabilized impinging flow with a longer potential core was found for the multi-slot jet configuration. This led to increased pressure gradient and increased shear stresses in the vicinity of the wiping region and, consequently, lower coating weights were obtained through use of the multi-slot air knife compared to the conventional single slot jet. Note de contenu : - Analytical model of film thickness
- Experimental setup
- Numerical simulation
- Results and discussion
- Table 1 : Working liquid properties in the experimental facilityDOI : https://doi.org/10.1007/s11998-021-00570-1 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-021-00570-1.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37152
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Code-barres Cote Support Localisation Section Disponibilité 23313 - Périodique Bibliothèque principale Documentaires Disponible