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Electricité / Paris : Nathan (1997)
Titre : Electricité : Courant continu, courant alternatif Type de document : texte imprimé Editeur : Paris : Nathan Année de publication : 1997 Collection : Etapes Sous-collection : Mémento num. 50 Importance : 127 p. Présentation : ill. Format : 22 cm. ISBN/ISSN/EAN : 2-09-177981-4 Note générale : Exercices résolus Langues : Français (fre) Catégories : Courants alternatifs
Courants continus
ElectricitéIndex. décimale : 621.3 Electrotechnique, électronique, télécommunications Résumé : Cet ouvrage s'adresse aux professionnels de l'électricité ; il est également destiné à tous ceux qui souhaitent se familiariser avec l'électricité. Parce qu'il regroupe les résultats essentiels de l'électricité élémentaire, cet ouvrage peut aussi constituer un aide-mémoire très utile aux étudiants et aux auditeurs de la formation permanente. Les auteurs ont choisi de privilégier l'observation et l'exploitation d'expériences plutôt que l'exposé de théories et le recours aux mathématiques. Ces connaissances peuvent suffire pour acquérir une bonne maîtrise de nombreux équipements électriques, la complexité des systèmes électriques excluant de plus en plus la possibilité d'acquérir les capacités nécessaires pour le dépannage et même parfois la maintenance. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=70 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 0239 621.3 ELE Monographie Bibliothèque principale Documentaires Disponible Extracellular protease activities of extremely halophilic archaea and their control via direct electric current / Meral Birbir in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 92, N° 2 (03-04/2008)
[article]
Titre : Extracellular protease activities of extremely halophilic archaea and their control via direct electric current Type de document : texte imprimé Auteurs : Meral Birbir, Auteur ; Z. B. Ozdogru, Auteur ; Yasar Birbir, Auteur ; Ayse Ogan, Auteur Année de publication : 2008 Article en page(s) : p. 53-58 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Bactéries halophiles
Bain de saumure
Courants continus
Cuirs et peaux -- Conservation
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.
Microbiologie
PeptidasesIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Proteolytic enzymes which are produced by extremely halophilic Archaea present in salt may cause serious damage on salted hides and may result in significant economic losses in the leather industry. Hence, protease activities of 24 protease producing extremely halophilic archaeal strains isolated from Tuz Lake, Kaldırım and Kayacık salterns and Tuzköy salt mine were determined in this study. The protease activities of Tuz Lake, Kaldırım saltern, Kayacık saltern and Tuzköy salt mine strains were found as between 80.0 and 83.3, 81.1 and 83.8, 83.3 and 83.4, 82.0 and 83.4 Units, respectively. To prevent proteolytic haloarchaeal damage on brine cured hides, the protease producing strains were treated with 0.5A direct electric current for 20min. Although proteolytic strains of Tuz Lake and Tuzköy salt mine in the liquid gelatin media were killed by 0.5A direct electric current within 15min, 10min direct electric current treatment were enough to kill all proteolytic strains of Kaldırım and Kayacık salterns. Also, the effect of 0.5A direct electric current on protease activities of the test strains was examined during 20min treatment in this study. It was found that 0.5A direct electric current caused a slight decrease on protease activities of the test strains. Therefore, it is necessary to kill protease producing strains in brine solution with direct electric current before the excretion of their protease into the brine solution. Note de contenu :
- Extremely halophilic strain
- Protease activities of the extremely halophilic strains
- Inactivation of the test strains with 0.5A direct electric current
- Table 1 : Protease activities of extremely halophilic Archaea isolated from Tuz Lake, Kaldırım and Kayacık Salterns and Tuzköy Salt Mine
- Table 2 : Voltage, temperature and rf values of 4 mixed proteolytic halophilic Archaea inactivated in the liquid gelatin media by 0.5A direct electric current within 20 minutes
- Table 3 : The effect of 0.5A direct electric current on protease activities of some of the test strains during 20 minutes treatmentEn ligne : https://drive.google.com/file/d/1gBbMoBdjmpLA6cnCaGdQjxhmAhOnxKZz/view?usp=share [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38930
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 92, N° 2 (03-04/2008) . - p. 53-58[article]Negative effects of haloversatile bacteria in salt on skins and their control with direct electric current in the leather industry / Haider Sabah Abdulhusein in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 107, N° 6 (11-12/2023)
[article]
Titre : Negative effects of haloversatile bacteria in salt on skins and their control with direct electric current in the leather industry Type de document : texte imprimé Auteurs : Haider Sabah Abdulhusein, Auteur ; Pinar Caglayan, Auteur ; Meral Birbir, Auteur ; Yasar Birbir, Auteur Année de publication : 2023 Article en page(s) : p. 207-214 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Bactéries haloversatiles
Courants continus
Cuirs et peaux -- Conservation
Cuirs et peaux de chèvres
Cuirs et peaux de moutons
Microbiologie
Sels de sodiumIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : The salt preservation method has been used for a long time in the leather industries with salt applied to raw skins and hides in order to control bacterial activity and to remove the moisture found in the skin structure. It is known that the salt used in curing process contains many halophilic bacterial species.
During the salting process, skins and hides might be contaminated with these micro-organisms. The goal of this research was to determine factors including the pH of salt samples, total count of haloversatile bacteria, proteolytic haloversatile bacteria, and lipolytic haloversatile bacteria found in these samples and to isolate, and identify haloversatile bacteria from the salt samples, to test their ability to use various amino acid and sugar sources, to characterise their enzymatic properties, to investigate their adverse effects on sheepskinand goatskin samples using a scanning electron microscopy. In addition, 2.5A direct electric current was applied against mixed culture of enzyme-producing haloversatile bacteria in 15% NaCl solution to search for an alternative environmentally friendly preservation method for skin/hide curing. The pH values of salt samples were found to be between 7.60 and 8.04.
The total counts of haloversatile bacteria, proteolytic haloversatile bacteria and lipolytic haloversatile bacteria were found to be 6 × 103CFU/g to 1.3 × 105CFU/g; 1×103-7×103CFU/g and 1.4 × 103-3.1 × 104CFU/g, respectively. 35 haloversatile bacteria belonging to ten different genera (Staphylococcus, Corynebacterium, Peribacillus, Lysinibacillus, Kocuria, Paenibacillus, Bhargavaea, Bacillus, Pseudomonas and Micrococcus) were isolated and identified from the salt samples.
The ability of haloversatile bacteria to use sugars and amino acids varied from one genus to another genus. While catalase, esterase, urease, protease, caseinase, lipase, xylanase, cellulase, amylase, DNase and oxidase enzymes were produced among the isolates, pullulanase enzyme was not produced. The scanning electron microscope micrographs showed that enzyme-producing haloversatile bacteria had significant effects on goatskin and sheepskin. The total number of the mixed culture was reduced from 3.6 × 106CFU/mL to 4×101CFU/mL within 17 minutes, and all cells were completely killed within 21 minutes.
The scanning electron micrographs showed that the structure and the organoleptic characterictics of bacteria treated sheepskin and goatskin samples were negatively changed at the end of 40-days storage.Note de contenu : - Salt sample collection and measuring pH value of salt samples
- Determination of the total numbers of haloversatile bacteria in the salt samples
- Determination of the total numbers of proteolytic and lipolytic haloversatile bacteria in salt samples
- Isolation of haloversatile bacteria
- Identification of haloversatile isolates according to 16S rRNA gene sequence analyses
- Nucleotide accession number
- Effects of different NaCl concentrations, pH values and temperature on haloversatile bacterial growth
- Investigation of enzymatic properties of haloversatile bacteria
- Utilisation of different amino acids and different carbon sources by haloversatile bacteria
- Investigation the effects of the mixed culture of enzyme producing haloversatile isolates on sheepskin and goatskin
- Extermination of haloversatile bacteria by direct electric current
- Investigation of the bacterial cells before and after the treatment with direct electric current by scanning electron microscopy
- Table 1 : The pH values, total counts of haloversatile bacteria, proteolytic haloversatile bacteria and lipolytic haloversatile bacteria in the salt samples
- Table 2 : The effects of pH, NaCl contents and temperature values on bacterial growth
- Table 3 : Enzymatic properties of haloversatile bacterial isolates
- Table 4 : Utilization of different amino acids by haloversatile isolates
- Table 5 : Utilisation of different sugars by haloversatile isolates
- Table 6 : The pH values, temperature and the total counts (CFU/mL) of enzyme producing haloversatile bacteria in the direct electric current treatmentEn ligne : https://drive.google.com/file/d/1qRfWv_CwzI3WQkn8QhrK0n0Rq2zPAjwb/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40239
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 107, N° 6 (11-12/2023) . - p. 207-214[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 24370 - Périodique Bibliothèque principale Documentaires Sorti jusqu'au 14/05/2024