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Collagen D-spacing and the effect of fat liquor addition / Katie H. Sizeland in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CX, N° 3 (03/2015)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CX, N° 3 (03/2015) . - p. 66-71 Titre : Collagen D-spacing and the effect of fat liquor addition Type de document : texte imprimé Auteurs : Katie H. Sizeland, Auteur ; Hannah C. Wells, Auteur ; G. E. Norris, Auteur ; Richard L. Edmonds, Auteur ; Nigel Kirby, Auteur ; A. Hawley, Auteur ; S. T. Mudie, Auteur ; Richard G. Haverkamp, Auteur Année de publication : 2015 Article en page(s) : p. 66-71 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Collagène Lanoline Produits de nourriture du cuir Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The physical properties of leather are partly a result of the structure of the leather’s network of type I collagen fibrils. To achieve high strength and a soft, supple feel, penetrating oils (usually polyols) are added to leather during manufacture, and this process is known as fat liquoring. The modification of the collagen structure by fat liquoring (with a lanolin-based fat liquor) is investigated using synchrotron-based small angle X-ray scattering. The axial periodicity, or D-spacing, of the collagen changes as a result of fat liquoring. With no fat liquor, the D-spacing is 60.2 nm; spacing increases by 6% to 63.6 nm at 10% fat liquor. Pure lanolin results in a similar increase in D-spacing. We discuss mechanisms for fibril elongation brought about by fat liquoring. The observations of structural changes taking place within collagen fibrils as a result of fat liquoring provides new insight into the nature of fat liquoring and informs future processing developments. En ligne : https://drive.google.com/file/d/1OE6eYCsce54i3IpZmfe6cnLKLoymJuH-/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23451 [article]

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Kinetics of inhibition of type I collagenase by dialdehyde cellulose in stabilization of type I collagen / Gladstone Christopher Jayakumar in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CX, N° 3 (03/2015)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CX, N° 3 (03/2015) . - p. 72-79 Titre : Kinetics of inhibition of type I collagenase by dialdehyde cellulose in stabilization of type I collagen Type de document : texte imprimé Auteurs : Gladstone Christopher Jayakumar, Auteur ; Nagarajan Usharani, Auteur ; Arjunan Yasothai, Auteur ; Swarna Vinodh Kanth, Auteur ; Jonnalagadda Raghava Rao, Auteur Année de publication : 2015 Article en page(s) : p. 72-79 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Antienzymes Cellulose dialdéhyde Collagénases Les collagénases sont des enzymes capables de rompre les liaisons peptidiques du collagène. Elles facilitent la destruction des structures extracellulaires lors de la pathogenèse bactérienne. Ce sont des exotoxines. La production de collagénases peut être induite lors d'une réponse immunitaire, par les cytokines qui stimulent les cellules telles que les fibroblastes et les ostéoplastes et occasionnent indirectement des lésions tissulaires. Collagène -- Stabilité Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Collagen is one of the widely studied biomaterial for various industrial applications. However, search of eco-friendly and biocompatible stabilizing agent is a thrust research domain. In this research work, application of dialdehyde cellulose (DAC) was studied to understand the effect on the enzymatic and conformational stability in collagen. The secondary structure of collagen is not significantly altered on interaction with DAC. But, it was found that DAC lead to changes in the amplitude of the circular dichroic (CD) spectrum but did not alter the triple helical conformation of collagen. DAC treated collagen exhibited 93% resistance to collagenolytic hydrolysis. Conversely, DAC treated collagenase exhibited 89% inhibition against collagen degradation and the inhibition was found to be concentration dependent. The kinetics of inhibition of collagenase by DAC was derived from the extent of hydrolysis of (2-furanacryloyl-L-leucyl-glycyl-L-prolyl-L-alanine), FALGPA. DAC exhibited non-competitive mode of inhibition against collagenase. CD data on DAC-modified collagenase substantiate the hypothesis that the inhibition of collagenase by DAC arises from secondary and quaternary structural changes in the enzyme. Gaining new insights in understanding the mechanism of stabilization of collagen by DAC through kinetics of inhibition of collagenase was presented. Note de contenu : - MATERIALS AND METHODS : Materials - Methods - Preparation of DAC - Preparation of crosslinked collagen - Resistance to collagenase - Inhibition of collagenase activity - Kinetic investigation - Inhibition of collagenase by DAC - Conformational changes of DAC stabilized collagen - RESULTS AND DISCUSSION : Inhibition of collagenase - DAC treated collagenase resistance of native collagen - Conformational changes in DAC stabilized collagen - Conformational changes in DAC treated collagenase - Kinetic analysis of inhibition of collagenase by DAC - Mechanism of inhibition of collagenase by DAC En ligne : https://drive.google.com/file/d/1SE-oSDIEYjm4_Qrm6DaXeblWS7zipi-Z/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23452 [article]

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Studies on tara-phosphonium combination tannage : approach towards a metal free eco-benign tanning system / Rathinam Aravindhan in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CX, N° 3 (03/2015)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CX, N° 3 (03/2015) . - p. 80-87 Titre : Studies on tara-phosphonium combination tannage : approach towards a metal free eco-benign tanning system Type de document : texte imprimé Auteurs : Rathinam Aravindhan, Auteur ; Balaraman Madhan, Auteur ; Jonnalagadda Raghava Rao, Auteur Année de publication : 2015 Article en page(s) : p. 80-87 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Environnement -- Etudes d'impact Sulfate de tétrakis hydroxyméthyl phosphonium Le sulfate de tétrakis hydroxyméthyl phosphonium est un myxobactéricide qui offre une prévention efficace contre les biofilms microbiens dans les eaux de traitement, et ce, pour une vaste gamme de micro-organismes formant des biofilms. Le sulfate de tétrakis (hydroxyméthyl) phosphonium agit principalement en augmentant la perméabilité de la membrane externe de l'enveloppe de la cellule microbienne, ce qui entraîne la libération rapide de protéines et d'autres substances cellulaires par les cellules. En outre, le sulfate de tétrakis (hydroxyméthyl) phosphonium inhibe le processus de sulfatoréduction dans les bactéries réductrices de sulfate. Tannage combiné Le tannage combiné se dit des tannages qui allient deux familles ou genre de tannage pour obtenir un résultat additionnant les qualités complémentaires des tannins mis en Å“uvre par exemple Chrome-Végétal ou Chrome-Synthétique Tara et constituants C'est un petit arbre épineux avec des gousses plates rouge qui pousse dans les zones sèches du Pérou, Amérique du Sud. Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : One of the important criteria determining the sustainability of an industrial activity is the ecological acceptability of the processing methods. Tanners throughout the world are looking for alternative eco friendly tanning systems. In the present work, metal free tanning system using a combination of Tetrakis Hydroxymethyl Phosphonium Sulphate (THPS) and Tara has been developed. This combination tanning is expected to be an effective eco-friendly mineral free tanning. The shrinkage temperature of the leathers obtained is 88°C. The tanning system is versatile in terms of processing both upper and garment leathers. The physical strength characteristics and organoleptic properties of the leathers obtained are comparable to that of chrome tanned leather. Environmental impact assessment shows that there is reduction in total solids when compared to control chrome tanning. Tara as a combination tanning agent not only improves the leather properties but also can act as a scavenger of free formaldehyde present in THPS tanned leather. Note de contenu : - MATERIALS AND METHODS : Determination of shrinkage temperature - THPS tara combination tanning - Post Tanning process - Objective assessment of softness through compressibility - Physical testing and hand evaluation of leathers - Color measurement - Environmental impact assessment - RESULTS AND DISCUSSION : THPS-tara combination tanning : optimization of offer of tara - Optimization of order of addition of tanning agents (THPS and tara) - Preparation of garment leathers - Color measurements - Softness measurements - Environmental impact of THPS - Tara combination tanning system - Role of tara in scavenging of free formaldehyde formed due to THPS En ligne : https://drive.google.com/file/d/1w-F09wpWH67txRrihNaOdYQUCDhj2jXI/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23453 [article]

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Characterization of mechanical properties of leather with airborne ultrasonics / Cheng-Kung Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CX, N° 3 (03/2015)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CX, N° 3 (03/2015) . - p. 88-93 Titre : Characterization of mechanical properties of leather with airborne ultrasonics Type de document : texte imprimé Auteurs : Cheng-Kung Liu, Auteur ; Nicholas P. Latona, Auteur ; Maryann M. Taylor, Auteur ; Christopher Eble, Auteur ; Mila L. Adelma-Ramos, Auteur Année de publication : 2015 Article en page(s) : p. 88-93 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation Contrôle non destructif Cuir Cuirs et peaux -- Propriétés mécaniques Qualité -- Contrôle Ultrasons Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : A nondestructive method to accurately evaluate the quality of hides and leather is urgently needed by leather and hide industries. Effects have been made to develop airborne ultrasonic (AU) testing method using non-contact transducers to evaluate the quality of hides and leather. We previously reported the research results demonstrating the AU technology for revealing defects in hides and leather that were difficult to be found during visual inspection. Recently new research was carried out to develop AU methods to nondestructively characterize the mechanical properties of leather. Observations showed a strong correlation between the mechanical properties of leather and the corresponding AU parameters based on the distribution of the transmission time (time of flight) through leather. We also used this nondestructive method to characterize the grain break of leather. Results showed the difference in grain break could be determined from the AU parameters collected from moving the AU sensors over a leather sample. Observations showed the poorer the grain break, the higher the time of flight distribution. In short, this study demonstrated that the tensile strength, stiffness, toughness and grain break could be nondestructively determined by AU. Note de contenu : - Leather stiffness - Leather toughness - AU evaluation of break En ligne : https://drive.google.com/file/d/1lGsPX5493oM81gjPwu9HM5Ozjp0S1hCD/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23454 [article]

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