Changes to the collagen structure using vibrational spectroscopy and chemometrics : a comparison between chemical and sulfide-free leather process / Megha Mehta in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVI, N° 11 (11/2021)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVI, N° 11 (11/2021) . - p. 379-387 Titre : Changes to the collagen structure using vibrational spectroscopy and chemometrics : a comparison between chemical and sulfide-free leather process Type de document : texte imprimé Auteurs : Megha Mehta, Auteur ; Yang Liu, Auteur ; Rafea Naffa, Auteur ; Mark Waterland, Auteur ; Geoff Holmes, Auteur Année de publication : 2021 Article en page(s) : p. 379-387 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Analyse multivariée Chimiométrie Collagène Enzymes protéolytiques Une enzyme protéolytique est une enzyme capable de couper une protéine en plusieurs fragments ou peptides. La trypsine, la papaïne, la pepsine, la chymotrypsine, la plasmine, la subtilisine... sont capables de couper une protéine, chaque enzyme étant spécifique de certains sites particuliers de cette protéine. C'est ainsi, par exemple, qu'une immunoglobuline G est découpée par la papaïne en un fragment Fc et deux fragments Fab, comme l'a montré Porter en 1959. Epilage enzymatique Matériaux -- Modifications chimiques Radiométrie Spectroscopie Raman Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Chemical and physical changes take place when hides and skins are processed to leather that affect the quality and strength of the material. Understanding the structure at each leather-making stage is the basis of this study but also intend to improve the process through a biochemical approach, employing a proteolytic enzyme for processing leather more cleanly with reduced environmental impact. Raman and ATR-FTIR spectroscopy in conjunction with chemometrics was used to investigate each leather-making stage from fresh green cattle hide to dry crust leather. The changes in proteins, lipids, nucleic acids and other biomolecules with leather processing was measured and reported using three novel Raman ratiometric markers, 920/1476, 1345/1259 and 1605/1476 cm-1, to discriminate the structural changes in collagen of hide using standard chemical and enzymatic method. Amide I band was deconvoluted to investigate thecollagen secondary structures using curve fitting by Gaussians function. The results of Principal Component Analysis are well-corroborated with the ratiometric markers of structural changes. Note de contenu : - EXPERIMENTAL : Materials - Enzymatic depilation - Data acquisition and spectral processing - RESULTS AND DISCUSSION : Fundamental characteristics of Raman spectra of standard and enzymatic processed hide - Radiometric analysis - Alterations in collagen network - Multivariate analysis DOI : https://doi.org/10.34314/jalca.v116i11.4659 En ligne : https://drive.google.com/file/d/1O4r23to9vBK4aAxPgMJizfFD5zzgmQ2M/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36575 [article]

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Comparative analysis of the proteomic profile of cattle hides that produce loose and tight leather using in-gel tryptic digestion followed by LC-MS/MS / Catherine Maidment in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 11 (11/2020)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXV, N° 11 (11/2020) . - p. 399-408 Titre : Comparative analysis of the proteomic profile of cattle hides that produce loose and tight leather using in-gel tryptic digestion followed by LC-MS/MS Type de document : texte imprimé Auteurs : Catherine Maidment, Auteur ; Meekyung Ahn, Auteur ; Rafea Naffa, Auteur ; Trevor Loo, Auteur ; Gillian Norris, Auteur Année de publication : 2020 Article en page(s) : p. 399-408 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Collagène Cuir lache Cuirs et peaux -- Analyse Cuirs et peaux -- Défauts Cuirs et peaux de bovins Extraction (chimie) Protéines Protéomique La protéomique désigne la science qui étudie les protéomes, c'est-à-dire l'ensemble des protéines d'une cellule, d'un organite, d'un tissu, d'un organe ou d'un organisme à un moment donné et sous des conditions données. Dans la pratique, la protéomique s'attache à identifier de manière globale les protéines extraites d'une culture cellulaire, d'un tissu ou d'un fluide biologique, leur localisation dans les compartiments cellulaires, leurs éventuelles modifications post-traductionnelles ainsi que leur quantité. Elle permet de quantifier les variations de leur taux d'expression en fonction du temps, de leur environnement, de leur état de développement, de leur état physiologique et pathologique, de l'espèce d'origine. Elle étudie aussi les interactions que les protéines ont avec d'autres protéines, avec l'ADN ou l'ARN, ou d'autres substances. La protéomique fonctionnelle étudie les fonctions de chaque protéine. La protéomique étudie enfin la structure primaire, secondaire et tertiaire des protéines. (Wikipedia) Statistique Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Looseness is a defect found in leather that reduces its quality by causing a wrinkly appearance in the finished product, resulting in a reduction in its value. Earlier studies on loose leather using microscopy and Raman spectroscopy reported a change in the collagen structure of loose leather. In this study, proteomics was used to investigate the possible molecular causes of looseness in the raw material, the first time such a study has been carried out. Proteins extracted from two regions of raw hide using two different methods were analysed; those taken from the distal axilla, an area prone to looseness, and those taken from the backbone which is less prone to looseness. Analyses using 1DE-LC-MS/MS showed that although the overall collagen concentration was similar in both areas of the hide, the distribution of the different types of collagen differed. Specifically, concentrations of type I collagen, and the collagen-associated proteoglycan decorin were lower in samples taken from the distal axilla, symptomatic of a collagen network with excess space seen for these samples using confocal microscopy. This study suggests a possible link between the molecular components of raw cattle hide and looseness and more importantly between the molecular components of skin and skin defects. There is therefore potential to develop biomarkers for looseness which will enable early preventative action. Note de contenu : - EXPERIMENTAL : chemicals - Sample preparation - Protein extraction - Protein digestion - LC-MS/MS - Protein identification - Statistical analysis - Total collagen concentration - 3D confocal microscopy - RESULTS AND DISCUSSION : Proteomic profiles : a comparison of the extraction methods - Differences between the OSP and DA regions of raw cattle hide - Table 1 : Proteins that are significantly down regulated in the DA DOI : https://doi.org/10.34314/jalca.v115i11.4184 En ligne : https://drive.google.com/file/d/1ve1EQeASe3mqkTpkqz0ZFQG6fgEMbxns/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34846 [article]

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Insights into the molecular composition of the skins and hides used in leather manufacture / Rafea Naffa in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIV, N° 1 (01/2019)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIV, N° 1 (01/2019) . - p. 29-36 Titre : Insights into the molecular composition of the skins and hides used in leather manufacture Type de document : texte imprimé Auteurs : Rafea Naffa, Auteur ; Catherine Maidment, Auteur ; Geoff Holmes ; Gillian Norris Année de publication : 2019 Article en page(s) : p. 29-36 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cuirs et peaux -- Analyse Cuirs et peaux de bovins Cuirs et peaux de chèvres Cuirs et peaux de daims Cuirs et peaux de moutons Structure moléculaire Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Increasing demand for information about the effects of the beamhouse processes on animal skins and hides led to the need to determine the differences among different animal skins and hides at molecular level which results in significant changes in their strength. This is a comprehensive study of the molecular components of four animal skins commonly used to manufacture shoes, clothing and furniture to identify common indicators of skin strength. First, the strength of each species was assessed using tear strength and the denaturation temperature. Then the concentration of the following molecular compounds: amino acids, natural collagen crosslinks and glycosaminoglycans (GAGs) were determined. Significant differences in their molecular compositions were found particularly the types and amount of the natural collagen crosslinks which are known to be essential for skin strength. We found that sheep skin contained the lowest collagen content and highest GAG concentrations compared to goat and deer skins and cow hide. To the best of our knowledge, this is the first time where the collagen crosslinks of skin and hide of different species are measured and compared. This study shows that different species have different underlying molecular composition of skins and hides resulting in strength differences. This understanding will help to modify the current leather processing protocols to produce stronger leather. Note de contenu : - EXPERIMENTAL : Chemicals & reagents - Preparation of skin samples - Skin thickness measurements - Tear strength of sheep, goat, deer skins and cow hide - Differential scanning calorimetry (DSC) of sheep, goat, deer skins and cow hide - Amino acid extraction from sheep, goat, deer skins and cow hide - Derivatization of amino acids by 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate - Separation of AQC deeivatized amino acids - Extraction and quantitation of glycosaminoglycans in skins - RESULTS AND DISCUSSION : Tear strength of sheep, goat, deer skins and cow hide - Differential scanning calorimetry (DSC) of sheep, goat and deer skins and cow hide - Amino acid composition of sheep, goat and deer skins and cow hide - Collagen I/III ratio in sheep, goat and deer skins and and cow hide - Quantitation of glycosaminoglycans (GAGs) in sheep, goat and deer skins and cow hide - Analysis of crosslinks in sheep, goat and deer skins and cow hide En ligne : https://drive.google.com/file/d/1EPPwJTQrMvg0M1XYcXbJjQzwk94mxEY7/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=31551 [article]

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Learning to recognize irregular feature on leather surfaces / Masood Aslam in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVI, N° 5 (05/2021)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVI, N° 5 (05/2021) . - p. 169-178 Titre : Learning to recognize irregular feature on leather surfaces Type de document : texte imprimé Auteurs : Masood Aslam, Auteur ; Tariq M. Khan, Auteur ; Syed Saud Naqvi, Auteur ; Geoff Holmes, Auteur ; Rafea Naffa, Auteur Année de publication : 2021 Article en page(s) : p. 169-178 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cuir Evaluation visuelle Qualité -- Contrôle Surfaces -- Analyse Wet-blue (tannage) Peau tannée au chrome (le chrome donne une couleur bleue) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : As part of industrial quality control in the leather industry, it is important to identify the abnormal features in wet-blue leather samples. Manual inspection of leather samples is the current norm in industrial settings. To comply with the current industrial standards that advocate large-scale automation, visual inspection based leather processing is imperative. Visual inspection of irregular surfaces is a challenging problem as the characteristics of the abnormalities can take a variety of shape and color variations. The aim of this work is to automatically categorize leather images into normal or abnormal by visual analysis of the surfaces. To achieve this aim, a deep learning based approach is devised that learns to recognize regular and irregular leather surfaces and categorize leather images on its basis. To this end, we propose an ensemble of multiple convolutional neural networks for classifying leather images. The proposed ensemble network exhibited competitive performance obtaining 92.68% test accuracy on our own curated leather images dataset. Note de contenu : - LITERATURE REVIEW - THE PROPOSED METHOD : Data augmentation - Convolutional neural network ensembles - Setting up the CNN and training process - Global average pooling - EXPERIMENTAL DESIGN : Dataset - Performance measures - Benchmark deep learning methods - State-of-the-art methods for comparison - RESULTS : Comparison with descriptors based machine learning methods - Comparison with deep learning based methods - Class Activations Maps (CAM) - Table 1 : Comparison of models parameters with and without the GAP layer - Table 2 : Computational complexity of pooling strategies - Table 3 : Hyper-parameter values used in algorithms - Table 4 : Comparison with the state-of-the-art methods in terms of classification accuracy. T acc stands for training accuracy, val acc for validation accuracy and test acc for test accuracy - Table 5 : Comparison of methods in terms of precision, recall, F1-score and AUC - Table 6 : Comparison of models in terms of accuracy, transfer learning, batch normalization, batch size using global average pooling and image size of 500 x 375 DOI : https://doi.org/10.34314/jalca.v116i5.4291 En ligne : https://drive.google.com/file/d/1Ubev3KPms4yofj6BFf-ZgdPRP_AoZado/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35760 [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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Raman and ATR-FTIR spectroscopy towards classification of wet blue bovine leather using ratiometric using ratiometric and chemometric analysis / Megha Mehta in JOURNAL OF LEATHER SCIENCE AND ENGINEERING, Vol. 2 (Année 2020)  

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