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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)
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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 protéolytiquesUne 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 RamanIndex. 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 analysisDOI : 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 : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36575
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVI, N° 11 (11/2021) . - p. 379-387[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 23063 - Périodique Bibliothèque principale Documentaires Disponible Monitoring the mode of action of synthetic and natural biocides against Aeromonas hydrophila by Raman spectroscopy and chemometrics / Megha Mehta in JOURNAL OF LEATHER SCIENCE AND ENGINEERING, Vol. 3 (Année 2021)
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Titre : Monitoring the mode of action of synthetic and natural biocides against Aeromonas hydrophila by Raman spectroscopy and chemometrics Type de document : texte imprimé Auteurs : Megha Mehta, Auteur ; Yang Liu, Auteur ; Mark Waterland, Auteur ; Geoff Holmes, Auteur Année de publication : 2021 Article en page(s) : 15 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Aeromonas hydrophila
Analyse multivariée
Antimicrobiens
Chimiométrie
Cuirs et peaux -- Conservation
Huile essentielle d'origan
Inhibiteurs (chimie)
Spectroscopie Raman
Thiocyano-méthylthiobenzotiazoleIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : We have investigated the mode of action of synthetic biocides, (2-(thiocyanomethylthio) benzothiazole(TCMTB), dichlorophen, (commonly used in leather industry for preservation) and natural biocides, oregano and eucalyptus oils, on Aeromonas hydrophila using Raman spectroscopy in collaboration with multivariate analysis and 2D correlation spectroscopy to evaluate whether Raman spectra acquired contained valuable information to study the action of biocides on bacterial cells. The growth of A. hydrophila in clear and outer edge zone of inhibition differ in their reaction with different biocides, which allows us to highlight the differences as a characteristic of two kinds of bacteria. Such classification helps identify oregano oil as the most effective biocide by altering clear and outer edge zone of bacteria. Standard disk diffusion assay method was used for screening biocide bacteria interactions and later analysed by Raman spectroscopy. The paper also presents the introduction of TCMTB and oregano oil into leather processing stages to examine and determine the antimicrobial effect as an application to real-world setting. Therefore, we conclude that Raman spectroscopy with appropriate computational tools constitutes a powerful approach for screening biocides, which provide solutions to all the industries using biocides including leather industry, considering the potentially harmful effect of biocides to humans and the environment. Note de contenu : - MATERIALS AND METHODS : Biocides and bacteria - Biocides, bacteria and leather treatment - Data acquisition and Raman spectral processing
- RESULTS AND DISCUSSION : Disk diffusion agar plate test - Raman spectroscopy identifies biomolecular changes due to biocide treatment - Multivariate analysis - Two-dimensional correlation spectroscopy (2D-COS) - Antimicrobial effect of leather treated with biocides
- Table 1 : Disk diffusion determined zones of inhibition (mm) for A. hydrophila strain after treatment with TCMTB, DCP, oregano oil and eucalyptus oilDOI : https://doi.org/10.1186/s42825-021-00062-3 En ligne : https://link.springer.com/content/pdf/10.1186/s42825-021-00062-3.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37546
in JOURNAL OF LEATHER SCIENCE AND ENGINEERING > Vol. 3 (Année 2021) . - 15 p.[article]Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire 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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Titre : Raman and ATR-FTIR spectroscopy towards classification of wet blue bovine leather using ratiometric using ratiometric and chemometric analysis Type de document : texte imprimé Auteurs : Megha Mehta, Auteur ; Rafea Naffa, Auteur ; Catherine Maidment, Auteur ; Geoff Holmes, Auteur ; Mark Waterland, Auteur Année de publication : 2020 Article en page(s) : 15 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse multivariée
Cuirs et peaux -- Analyse
Cuirs et peaux -- Défauts
Cuirs et peaux de bovins
Réflexion totale atténuée
Spectroscopie Raman
Wet-blue (tannage)Peau tannée au chrome (le chrome donne une couleur bleue)Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : There is a substantial loss of value in bovine leather every year due to a leather quality defect known as “looseness”. Data show that 7% of domestic hide production is affected to some degree, with a loss of $35 m in export returns. This investigation is devoted to gaining a better understanding of tight and loose wet blue leather based on vibrational spectroscopy observations of its structural variations caused by physical and chemical changes that also affect the tensile and tear strength. Several regions from the wet blue leather were selected for analysis. Samples of wet blue bovine leather were collected and studied in the sliced form using Raman spectroscopy (using 532 nm excitation laser) and Attenuated Total Reflectance - Fourier Transform InfraRed (ATR-FTIR) spectroscopy. The purpose of this study was to use ATR-FTIR and Raman spectra to classify distal axilla (DA) and official sampling position (OSP) leather samples and then employ univariate or multivariate analysis or both. For univariate analysis, the 1448 cm− 1 (CH2 deformation) band and the 1669 cm− 1 (Amide I) band were used for evaluating the lipid-to-protein ratio from OSP and DA Raman and IR spectra as indicators of leather quality. Curve-fitting by the sums-of-Gaussians method was used to calculate the peak area ratios of 1448 and 1669 cm− 1 band. The ratio values obtained for DA and OSP are 0.57 ± 0.099, 0.73 ± 0.063 for Raman and 0.40 ± 0.06 and 0.50 ± 0.09 for ATR-FTIR. The results provide significant insight into how these regions can be classified. Further, to identify the spectral changes in the secondary structures of collagen, the Amide I region (1600–1700 cm− 1) was investigated and curve-fitted-area ratios were calculated. The 1648:1681 cm− 1 (non-reducing: reducing collagen types) band area ratios were used for Raman and 1632:1650 cm− 1 (triple helix: α-like helix collagen) for IR. The ratios show a significant difference between the two classes. To support this qualitative analysis, logistic regression was performed on the univariate data to classify the samples quantitatively into one of the two groups. Accuracy for Raman data was 90% and for ATR-FTIR data 100%. Both Raman and ATR-FTIR complemented each other very well in differentiating the two groups. As a comparison, and to reconfirm the classification, multivariate analysis was performed using Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA). The results obtained indicate good classification between the two leather groups based on protein and lipid content. Principal component score 2 (PC2) distinguishes OSP and DA by symmetrically grouping samples at positive and negative extremes. The study demonstrates an excellent model for wider research on vibrational spectroscopy for early and rapid diagnosis of leather quality. Note de contenu : - EXPERIMENTAL : Sample preparation - Data acquisition and spectral processing
- RESULTS AND DISCUSSION : Peaks of interest - Univariate analysis - Multivariate analysis
- Table 1 : Raman and infrared spectroscopic band assignments for Wet Blue leather
- Table 2 : Raman band assignments distinguishing loose and tight wet blue leather
- Table 3 : Deconvoluted amide I band assignments for protein secondary structures
- Table 4 : Confusion matrix for Raman univariate analysis
- Table 5 : Confusion matrix for IR univariate analysis
- Table 6 : Confusion matrix for the classification of OSP and DA based on the PCA-LDA modelDOI : 10.1186/s42825-019-0017-5 En ligne : https://link.springer.com/content/pdf/10.1186/s42825-019-0017-5.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37139
in JOURNAL OF LEATHER SCIENCE AND ENGINEERING > Vol. 2 (Année 2020) . - 15 p.[article]Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire