Collagen structure changes during chrome tanning in propylene carbonate / Yi Zhang in JOURNAL OF LEATHER SCIENCE AND ENGINEERING, Vol. 1 (Année 2019)  

[article]  inJOURNAL OF LEATHER SCIENCE AND ENGINEERING > Vol. 1 (Année 2019) . - 7 p. Titre : Collagen structure changes during chrome tanning in propylene carbonate Type de document : texte imprimé Auteurs : Yi Zhang, Auteur ; Jenna Kate Buchanan, Auteur ; Geoff Holmes, Auteur ; Bradley William Mansel, Auteur ; Sujay Prabakar, Auteur Année de publication : 2019 Article en page(s) : 7 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse thermique Carbonate de propylène Collagène -- Structure Cuirs et peaux Diffusion de la lumière aux petits angles Tannage au chrome Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Green solvents, such as propylene carbonate (PC), can be used in leather processing to improve the efficiency of chrome tanning and reduce wastewater. Here we report a combined small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) study on PC and its efficacy as a carrier medium during chrome tanning. SAXS analysis on the collagen structure of chrome tanned leather using PC, compared to conventionally tanned leather using water, showed an increase in Cr uptake in addition to the more uniform penetration of Cr through the leather cross-section. The increased binding of Cr to the collagen matrix drives the decreased hydration environment of the collagen triple helix. Furthermore, DSC studies show a uniform hydrothermal stability for the PC samples due to the more even distribution of Cr through the collagen matrix. Understanding the mechanisms by which chrome tanning occurs in non-aqueous solvents can guide us towards a more sustainable future for the leather industry. Note de contenu : - EXPERIMENTAL : Materials - Leather sample preparation - Small-angle X-ray scattering (SAXS) measurements - Differential scanning calorimetry (DSC) measurements - Percentage uptake of chromium - RESULTS AND DISCUSSION : Chromium uptake from AAS studies - SAXS peak changes with tanning - D-period changes through the leather cross-section - Changes in R6/5 - DSC studies DOI : https://doi.org/10.1186/s42825-019-0011-y En ligne : https://link.springer.com/content/pdf/10.1186/s42825-019-0011-y.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36953 [article]

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Quantitative and structural analysis of isotopically labelled natural crosslinks in type I skin collagen using LC-HRMS and SANS / Yi Zhang in JOURNAL OF LEATHER SCIENCE AND ENGINEERING, Vol. 1 (Année 2019)  

[article]  inJOURNAL OF LEATHER SCIENCE AND ENGINEERING > Vol. 1 (Année 2019) . - 9 p. Titre : Quantitative and structural analysis of isotopically labelled natural crosslinks in type I skin collagen using LC-HRMS and SANS Type de document : texte imprimé Auteurs : Yi Zhang, Auteur ; Rafea Naffa, Auteur ; Christopher J. Garvey, Auteur ; Catherine Maidment, Auteur ; Sujay Prabakar, Auteur Année de publication : 2019 Article en page(s) : 9 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse quantitative (chimie) Chromatographie en phase liquide Collagène -- Structure Cuirs et peaux Réticulation (polymérisation) Spectrométrie de masse Traceurs radioactifs Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Collagen structure in biological tissues imparts its intrinsic physical properties by the formation of several covalent crosslinks. For the first time, two major crosslinks in the skin dihydroxylysinonorleucine (HLNL) and histidinohydroxymerodesmosine (HHMD), were isotopically labelled and then analysed by liquid-chromatography high-resolution accurate-mass mass spectrometry (LC-HRMS) and small-angle neutron scattering (SANS). The isotopic labelling followed by LC-HRMS confirmed the presence of one imino group in both HLNL and HHMD, making them more susceptible to degrade at low pH. The structural changes in collagen due to extreme changes in the pH and chrome tanning were highlighted by the SANS contrast variation between isotopic labelled and unlabelled crosslinks. This provided a better understanding of the interaction of natural crosslinks with the chromium sulphate in collagen suggesting that the development of a benign crosslinking method can help retain the intrinsic physical properties of the leather. This analytical method can also be applied to study artificial crosslinking in other collagenous tissues for biomedical applications. Note de contenu : - EXPERIMENTAL METHODS : Materials and methods - RESULTS AND DISCUSSION : Characterization of natural crosslinks in skin collagen : isotopic labelling using NaBD4 and mechanism of HHMD formation - Quantification of natural crosslinks in skin collagen : relationship with pH and crosslinking conditions - Structural analysis of skin collagen : interplay between natural and artificial crosslinks - Table 1 : Collagen D-periodicity at different processing stages in control, reduced and labelled skin samples. The D-period decreased for all samples starting from raw to the pickled stage, then increased at the crosslinked stage DOI : https://doi.org/10.1186/s42825-019-0012-x En ligne : https://link.springer.com/content/pdf/10.1186/s42825-019-0012-x.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36955 [article]

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Studies on collagen structure using X-ray scattering on a closed-loop leather process / Yi Zhang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 10 (10/2020)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXV, N° 10 (10/2020) . - p. 373-379 Titre : Studies on collagen structure using X-ray scattering on a closed-loop leather process Type de document : texte imprimé Auteurs : Yi Zhang, Auteur ; Jenna Buchanan, Auteur ; Jiasheng Su, Auteur ; Zhuangdou Zhang, Auteur ; Geoff Holmes, Auteur ; Sujay Prabakar, Auteur Année de publication : 2020 Article en page(s) : p. 373-379 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Collagène -- Analyse Cuirs et peaux -- Déchets -- Recyclage Diffractométrie de rayons X Diffusion aux petits angles Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Waste management in leather processing is crucial in limiting the excess use of hazardous materials that lead to environmental pollution and health concerns. A closed-loop approach was developed to recycle the spent solutions from leather processing to reduce waste in the effluent. The structural changes of collagen that accompany such processing are yet to be studied and is crucial in understanding the closed-loop process and its subsequent leather properties. In this study, we analysed the collagen structure at different processing stages across the closed-loop approach using synchrotron small-angle X-ray scattering. An increased filling effect in the collagen matrix was observed and attributed to the residual organic component and chromium species in recycled spent solutions. A high uptake of chromium was also observed from the increased scattering intensity from leathers treated with recycled chrome solution, indicating its efficient use. Additionally, the changes in scattering intensity from keratin and lipids indicated an effective unhairing process. Such findings on collagen structure changes will support the development of more environmentally and economically sustainable processing methods to benefit the leather industry. Note de contenu : - Sample preparation - Small-angle X-ray scattering (SAXS) DOI : https://doi.org/10.34314/jalca.v115i10.4175 En ligne : https://drive.google.com/file/d/1B-AuPs8xRaBRWnOHDBZ7bKgDVRzJMpeE/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34612 [article]

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The effect of cloisite Na+ nanoclay filler on the morphology and mechanical properties of loose leather / Sujay Prabakar in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXI, N° 5 (05/2016)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXI, N° 5 (05/2016) . - p. 178-184 Titre : The effect of cloisite Na+ nanoclay filler on the morphology and mechanical properties of loose leather Type de document : texte imprimé Auteurs : Sujay Prabakar, Auteur ; Catherine P. Whitby, Auteur ; Anna M. Henning, Auteur ; Geoff Holmes, Auteur Année de publication : 2016 Article en page(s) : p. 178-184 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Argile Caractérisation Charges (matériaux) Cloisite Cuirs et peaux -- Propriétés mécaniques Ions sodium Morphologie (matériaux) Nanoparticules Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Looseness describes a structural fault in leather, which leads to the development of wrinkles on the surface when the leather is bent inwards. It causes up to 7% of hides processed to finished leather to be downgraded or rejected at final inspection, requiring replacement and causing delay in meeting orders. Fillers can fill the interstitial spaces in loose leathers and make the looseness less pronounced. Here, the effect of Cloisite®Na+, ananoclay filler, on loose cattle hides is investigated by electron microscopy and mechanical characterization. Whilst SEM studies show an apparent filling effect in the grain-corium boundary at increasing concentrations of filler, TEM images show that at an optimum concentration of 3% uniform dispersion of the filler along with good handle can be obtained. A gradual increase in tensile and tear strength is observed with increasing concentration of Cloisite® Na+, however softness measurements correlated with microscopic observations in that only at optimum concentrations can both good handle and mechanical strength be achieved. We discuss a possible mechanism for the change in mechanical properties and handle of the loose leather after treating with Cloisite®Na+. The mechanistic study of such treatments on low quality hides will result in the production of leathers with more uniform cutting area and added functionality. Note de contenu : - EXPERIMENTAL SECTION : Materials - Application of cloisite Na+ to loose leather - Characterization - Physical and mechanical characterization - RESULTS AND DISCUSSION : Physical and mechanical studies of cloisite Na+ treated leather En ligne : https://drive.google.com/file/d/17ECa72PjdsqY5D0R0ZHqZ_lab41Qqjbn/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=26221 [article]

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Tying up loose ends / Geoff Holmes in LEATHER INTERNATIONAL, Vol. 217, N° 4863 (08/2016)  

[article]  inLEATHER INTERNATIONAL > Vol. 217, N° 4863 (08/2016) . - p. 17-18 Titre : Tying up loose ends Type de document : texte imprimé Auteurs : Geoff Holmes, Auteur ; Sujay Prabakar, Auteur ; Thijs van Stiphout, Auteur ; Petrik Galvosas, Auteur Année de publication : 2016 Article en page(s) : p. 17-18 Langues : Anglais (eng) Catégories : Collagène -- Détérioration Cuirs et peaux -- Analyse Cuirs et peaux -- Défauts Fleur du cuir Relachement (mécanique) Relaxometrie par résonance magnétique nucléaire Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The authors of this article have observed some excessive plumping in the flanks of limed split hides that has been correlated to looseness in crust leathers. But these observations only accurately predict downgrading in less than 30% of the hides we have pulled from production and processed through to leather, suggesting a tenuous connection at best. We have also seen a strong correlation between sammed wet-blue looseness, as measured using a modified TM 174 technique, and crust looseness in 32 regions of 1,000 hides followed through commercial production. The main issue with all these techniques is that they cannot identify looseness in the raw material. Other studios in this project are looking at the chemical composition of base and tight hides, and follow a similar protocol to the one adopted in this study, where five regions of suspected loose hides are sampled and the remaining hide processed through to leather to identify whether it is actually base or not. Our observations, from investigating looseness in cattle hides identified at the slaughter plant through to crust leather, is that looseness cannot be readily observed from information gathered on animal condition, breed, age or gender, but does become more obvious once the hides are processed, and can be readily seen in the cross-section of processed hides. Note de contenu : - Technical aspects - Control measures - What was observed - Project outcomes En ligne : https://drive.google.com/file/d/1Le8yr_8z5bP70Pr65d4eVnV6eqRy1ldt/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=26903 [article]

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