Near infrared and two-dimensional correlation infrared spectroscopic study on the heat denaturation of collagen in aqueous solution / Junling Guo in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CVII, N° 6 (06/2012)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CVII, N° 6 (06/2012) . - p. 205-212 Titre : Near infrared and two-dimensional correlation infrared spectroscopic study on the heat denaturation of collagen in aqueous solution Type de document : texte imprimé Auteurs : Junling Guo, Auteur ; Wenhua Zhang, Auteur ; Xuepin Liao, Auteur ; Bi Shi, Auteur Année de publication : 2012 Article en page(s) : p. 205-212 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Collagène -- Détérioration Cuirs et peaux Pyrolyse La pyrolyse est la décomposition ou thermolyse d'un composé organique par la chaleur pour obtenir d'autres produits (gaz et matière) qu'il ne contenait pas. L'opération est réalisée en l'absence d'oxygène ou en atmosphère pauvre en oxygène pour éviter l'oxydation et la combustion (L’opération ne produit donc pas de flamme). Il s'agit du premier stade de transformation thermique après la déshydratation. Elle permet généralement d'obtenir un solide carboné, une huile et un gaz. Elle débute à un niveau de température relativement bas (à partir de 200 °C) et se poursuit jusqu'à 1 000 °C environ. Selon la température, la proportion des trois composés résultants est différente. Solutions aqueuses (chimie) Spectroscopie infrarouge proche Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The thermal behaviors of collagen in aqueous solution were studied by in situ near infrared spectroscopy (NIR) and two-dimensional correlation infrared spectroscopy (2D-IR). The spectral data of water molecule and Amide I region fairly provided the dynamic details about the changes of water molecules and imino groups (–NH) in collagen under a temperature evolution from 25 to 54 °C. The splitting of combination bands of water molecule separately at 1455 nm and 1395 nm revealed that there are two different states of water molecules in collagen molecule, the surrounding free water molecules and the structural participating water molecules. Additionally, the two-step phase shift of the combination band of water molecule suggested that the interaction between collagen and water molecule experience two significant changes during the process of thermal denaturation transition. Based on the study of NIR and 2D-IR, a novel molecular model about the micro-changes of collagen from native to thermally denatured state was proposed. In this model, the breaking of hydrogen-bonded –NH groups occurs at first upon heating and the released –NH groups form hydrogen bonds with water molecules immediately to build a new stable water-mediated hydrogen-bonding structure simultaneously. With the increase of temperature, the collagen triple helix collapses gradually, accompanied by the breaking of water-mediated hydrogen bonds of inter-triple helix at 36 °C, and the breaking of intra-helix hydrogen bonds at 48 °C. Note de contenu : - EXPERIMENTAL : Materials - Near Infrared Spectroscopy measurements - Temperature-dependent two-dimensional correlation analysis - RESULTS AND DISCUSSION : Temperature-dependent near Infrared Spectroscopy Analysis - Two-dimensional correlation analysis of the temperature-dependent micro-dynamic changes En ligne : https://drive.google.com/file/d/1QYgkNYTxh4KJlvZNWbXd5gtyZq4tbTZ3/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15534 [article]

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The further investigation of tanning mechanisms of typical tannages by ultraviolet-visible and near infrared diffused reflectance spectrophotometry / Junling Guo in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CVI, N° 7 (07/2011)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CVI, N° 7 (07/2011) . - p. 226-231 Titre : The further investigation of tanning mechanisms of typical tannages by ultraviolet-visible and near infrared diffused reflectance spectrophotometry Type de document : texte imprimé Auteurs : Junling Guo, Auteur ; Xin Huang, Auteur ; Chao Wu, Auteur ; Xuepin Liao, Auteur ; Bi Shi, Auteur Année de publication : 2011 Article en page(s) : p. 226-231 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Alun Glutaraldéhyde Groupement carboxyle Spectrométrie infrarouge Spectrophotométrie UV-Visible Spectroscopie de réflectance Sulfate d'aluminium Sulfate de chrome Sulfate de fer Sulfate de titane Sulfate de zirconium Tannage Tannage végétal Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The ultraviolet-visible and near-infrared diffuse reflection (UV-Vis-NIR DR) spectroscopy was employed for further understanding the mechanisms of three kinds of classical tannages, including aldehyde tanning, vegetable tanning and mineral tanning. The NIR DR spectra of glutaraldehyde tanned leather exhibited a decreased peak intensity of amino group at 1475 nm, suggesting that the main reaction groups of collagen in aldehyde tanning are amino groups. Comparing the NIR DR spectra of pickled pelt and vegetable tanned leather, it was proved that the vegetable tanning is based on the mechanism of multiple hydrogen bonding interaction, where the amino groups, carboxyl groups and peptide chains are involved. As for mineral tannages, the tanning mechanisms of chromium sulfate, zirconium sulfate, ferrum sulfate, titanium sulfate and aluminum sulfate were investigated. Based on UV-Vis-NIR DR analysis in the wavelength range of 200 to 2070 nm, it was confirmed that the main reactions involved in mineral tanning are the chelating interactions of metal ions with both the carboxyl groups and the amino groups of collagen, although the reactivity of metal salts toward carboxyl groups is higher than toward amino groups. The reactivity of metal salts toward carboxyl groups of collagen follows the sequence of chromium salt > zirconium salt > ferrum salt > titanium salt > aluminum salt. However, the reactivity of metal salts to amino groups of collagen is in the sequence of zirconium salt > chromium salt > ferrum salt > titanium salt > aluminum salt. Meanwhile, the peptide chain of collagen was also found to play an important role in fixation of metal ions during tanning process. Note de contenu : EXPERIMENTAL : Preparation of leather samples - UV-Vis-NIR DR determinations. RESULTS AND DISCUSSION : Comparison and analysis of DR spectra of CF, GA-CF and BT-CF - Comparison and analysis of DR spectra of metal salts tanned leathers. En ligne : https://drive.google.com/file/d/1XMCv5rwTd7b_YqA_uIwFpuqj1DFNGr8M/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12032 [article]

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