Nanofibrous polypeptide hydrogels with collagen-like structure as biomimetic extracellular matrix / Chengkun Zhao in COLLAGEN AND LEATHER, Vol. 5 (2023)  

[article]  inCOLLAGEN AND LEATHER > Vol. 5 (2023) . - 13 p. Titre : Nanofibrous polypeptide hydrogels with collagen-like structure as biomimetic extracellular matrix Type de document : texte imprimé Auteurs : Chengkun Zhao, Auteur ; Xing Li, Auteur ; Shaoquan Bian, Auteur ; Weinan Zeng, Auteur ; Alfredo Ronca, Auteur ; Ugo D'Amora, Auteur ; Maria Grazia Raucci, Auteur ; Jie Liang, Auteur ; Yong Sun, Auteur ; Qing Jiang, Auteur ; Yujiang Fan, Auteur ; Luigi Ambrosio, Auteur ; Xingdong Zhang, Auteur Année de publication : 2023 Article en page(s) : 13 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Caractérisation Chimie biomimétique hydrocolloïdes Matrice extracellulaire Morphologie (matériaux) Nanofibres Polypeptides Un polypeptide est une chaîne d'acides aminés reliés par des liaisons peptidiques. On parle de polypeptide lorsque la chaîne contient entre 10 et 100 acides aminés. Au-dessus de 100 acides aminés on parle généralement de protéine. Parmi eux, les peptides multi-cycliques, les peptides phosphorylés ou encore ceux intégrant des liaisons non-peptidiques ou des peptides conjugués. Certains polypeptides constituent une famille d'antibiotiques dont les molécules très toxiques n'en permettent qu'un usage très limité. D'autres s’imposent aujourd’hui comme des éléments essentiels à la mise au point de vaccins ou de principes actifs destinés aux traitements de certaines pathologies telles que les cancers, les déficiences hormonales, l’ostéoporose. Rhéologie Tests de toxicité Index. décimale : 547 Chimie organique : classer la biochimie à 574.192 Résumé : Supramolecular peptides exhibit obvious similarities with collagen fibers in terms of self-assembly characteristics, nanofibrous structure, and responsiveness to external stimuli. Here, a series of supramolecular peptides were developed by altering the amino acid sequence, enabling the self-assembly of three types of 4-biphenylacetic acid (BPAA)-tripeptides into fibrous hydrogel through hydrogen bonding and π–π stacking under the influence of ion induction. Transmission electron and scanning electron microscopies revealed that the diameter of the fiber within nanofibrous hydrogels was ~ 10 and ~ 40 nm, respectively, which was similar with the self-assembled collagen fibers. For this reason, these hydrogels could be considered as a biomimetic extracellular substitute. Meanwhile, the gelation concentration induced by ions was even lower than 0.66 wt%, with an elastic modulus of ~ 0.27 kPa, corresponding to a water content of 99.34 wt%. In addition, the three supramolecular hydrogels were found to be good substrates for L929 cell adhesion and MC-3T3 cell proliferation. The overall results implied that BPAA-based hydrogels have a lucrative application potential as cell carriers. Note de contenu : - EXPERIMENTAL SECTION : Materials and methods - The preparation of BPAA-tripeptides - The preparation of BPAA-tripeptides - Hydrogel preparation and morphological characterization - Rheology - CD and fluorescence emission measurements - Cytotoxicity test - BPAA-tripeptides hydrogels co-culture with L929 cells and MC-3T3 cells - ALP staining of BMSCs co-culture with BPAA-tripeptides - Statistics - RESULTS AND DISCUSSION : The design and optimization of BPAA-tripeptides - The self-assembled nanofibrillar structure of BPAA-tripeptides by changing the sequence of amino acid - Secondary structure and intermolecular interactions analyzed from CD and fluorescence emission spectroscopy - Viscoelastic property of peptides hydrogels through rheological testing - Impact of amino acid sequence change on biological properties DOI : https://doi.org/10.1186/s42825-022-00110-6 En ligne : https://link.springer.com/content/pdf/10.1186/s42825-022-00110-6.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40059 [article]

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Path planning algorithm for laser removal of paint from aircraft skin / Jie Liang in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 21, N° 2 (03/2024)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 21, N° 2 (03/2024) . - p. 537-546 Titre : Path planning algorithm for laser removal of paint from aircraft skin Type de document : texte imprimé Auteurs : Jie Liang, Auteur ; Zhichao Wang, Auteur ; Jianshe Gao, Auteur ; Kun Gao, Auteur Année de publication : 2024 Article en page(s) : p. 537-546 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Avions -- Revêtements:Avions -- Peinture lasers Revêtements -- Décapage:Peinture -- Décapage Index. décimale : 667.9 Revêtements et enduits Résumé : Laser paint removal technology has recently been used in aircraft maintenance because this technology is highly efficient, contact free and environment-friendly. This work proposes a tool path planning algorithm based on maximum defocus length, the distance between laser focus and the skin surface, that decreases the path points and the path length. Fewer interpolation points can generate smoother trajectory acceleration curves, reducing robot vibration and mechanical wear and improving robot response speed and accuracy to the planned path. Firstly, the STL (standard tessellation language) surface model of the aircraft metal skin is sliced using the section plane group to obtain the initial laser paint removal path. Secondly, the maximum defocus length is obtained by laser paint removal experiments on the skin. Thirdly, the initial path is optimized based on the path optimization algorithm of the maximum defocus length. Finally, a robotic paint removal verification experiment using the optimized path is conducted on a 0.0336 square meter section of a DR-5 unmanned aerial vehicle (UAV), composed of 2024-T6 aluminum. The results show that the application of this algorithm can remove the paint layer from the aircraft skin and decrease the path interpolation points by 96.2%. Note de contenu : - Path generation for laser paint removal : Initial path generation by slicing the STL model - Path optimization based on defocus length - Experiment setup : Materials and equipment - The acquisition of the maximum defocus length - Verification experiment - DISCUSSION : Analysis of the paint removal ratio - Analysis of the path points - As can be seen in Table 4, the number - Table 1 : The main laser parameters - Table 2 : Laser processing parameters - Table 3 : Paint thickness removal ratio with the different defocus lengths - Table 4 : The contrast of paths before and after optimization DOI : https://doi.org/10.1007/s11998-023-00836-w En ligne : https://drive.google.com/file/d/1d19GlBoAHOKa25DEx3V_r2LRUMGfG8dn/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40775 [article]

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