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Selection and characterization of DNA aptamers targeting the surface Borrelia protein CspZ with high-throughput cross-over SELEX
No full textInternational audienceLyme borreliosis (LB) is the most prevalent tick-borne illness, with an estimated 700 000 cases annually in the United States and Europe. The LB diagnosis based on a two-tiered serology remains controversial due to its indirect nature and low sensitivity during the early stage of the disease. Aptamers are single-stranded DNA or RNA oligonucleotides that exhibit high selectivity and specificity for their target due to their unique three-dimensional structure. By applying cross-over-SELEX process, an enrichment of DNA oligonucleotide sequences against a surface protein of Borrelia, named CspZ, has been performed and monitored using absorbance at 260 nm, melting curves and NGS analyses. Beyond sequence enrichment, oligonucleotides binding to CspZ were observed during the selection rounds by Dot Blot and beads assays. Thirteen unique and highly redundant oligonucleotide sequences were further characterized using multiple approaches such as Dot Blot, BioLayer Interferometry and Surface Plasmon Resonance. The selected aptamers showed K D values from tens of nanomolar to the micromolar range by BLI and SPR. Two aptamers, Apta9 and Apta10, characterized by flow cytometry and epifluorescence microscopy, were able to specifically recognize Borrelia burgdorferi sensu stricto. This strategy holds promise for the development of an improved diagnostic assay.</div
In Situ Synthesis of Iron Oxide-Polyisobutylene Multifunctional Nanocomposites: Size Control, Magnetic and Mechanical Properties Enhancement
No full textInternational audiencePolymer nanocomposites with precisely controlled nanoparticle size and narrow polydispersity offer substantialpotential for multifunctional applications, particularly in energy and healthcare. In this study, we introduce an in situ synthesis approach for creating iron oxide nanoparticle-polyisobutylene nanocomposites, where the nanoparticle size distribution and spatial dispersion are finely tuned by adjusting the polymer concentration and molecular weight. This method allows us to investigate and control the growth dynamics of nanoparticleswithin the polymer solution, providing insights into how the polymer molecular weight and concentration influence nucleation, growth, and assembly. Beyond achieving precise size control, our approach enables the rational design of nanocomposites with significantly enhanced mechanical strength, evidenced by an increased storage modulus, while preserving their superparamagnetic behavior. This strategy advances the development of high-performance magnetic polymer nanocomposites and opens up possibilities for applications that require both robust mechanical properties and responsive magnetic features, marking a significant step forward in nanocomposite design and functionality
Humanités numériques et études théâtrales: Construire une base de données pour un répertoire théâtral d'Ancien Régime : théories, pratiques, questions épistémologiques et écologiques
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Développement de modèles éléments finis de types volumique, volume-coque et volume-poutre pour l’analyse du comportement des structures multicouches en bois assemblées par des goujons
No full textMultilayered timber structures, assembled using densified wood dowels, represent a sustainable and innovative solution for the construction sector. The development of predictive finite element models requires a solid representation of the geometry for modelling the complex mechanical behaviour of these structures. However, solid models are costly, especially in the context of variability studies and optimization. In this thesis, solid, solid-shell, and solid-beam approaches are developed to obtain accurate models that can be considered as the best compromise. The study of the mechanical behaviour of multilayered timber structures reveals that the layers adopt a shell-like behaviour, while the dowels behave like beams. Higher-order displacement fields through the thickness of the layers and through the cross-section of the dowels are identified. To meet these displacement fields while maintaining a solid representation, two methods have been developed. A first method exploits standard solid elements by applying shell theories through the thickness of the layers and beam theories through the sections of the dowels. A second method uses a 32-node hexahedral element and is inspired by the principle of solid-shell and solid-beam elements, with a single element through the thickness of the layers and a single element through the section of the dowels. The results demonstrate that the methods proposed in this thesis lead to effective modelling tools for multilayered timber structures assembled with densified wood dowels. These methods offer perspectives for future developments and applications to other types of structures.Les structures multicouches en bois, assemblées par des goujons en bois densifié, constituent une solution durable et innovante pour le secteur de la construction. Le développement de modèles prédictifs par éléments finis nécessite une représentation volumique de la géométrie pour modéliser le comportement mécanique complexe de ces structures. Cependant, les modèles volumiques sont couteux, notamment dans le cadre des études de variabilité et d’optimisation. Dans cette thèse, des approches de types volumique, volume-coque et volume-poutre, sont développées pour obtenir des modèles précis et qui peuvent être qualifiés de juste nécessaires. L’étude du comportement mécanique des structures multicouches en bois révèle que les lamelles adoptent un comportement de coque tandis que les goujons se comportent comme des poutres. Des champs de déplacement d’ordre supérieur dans l’épaisseur des lamelles et dans la section des goujons sont identifiés. Pour respecter ces champs de déplacement tout en gardant une représentation volumique, deux méthodes ont été développées. Une première méthode exploite des éléments volumiques standards en appliquant des théories de coque à travers l’épaisseur des lamelles et des théories de poutre à travers les sections des goujons. Une seconde méthode exploite un élément hexaédrique à 32 nœuds et s’inspire des principes des éléments volume-coque et volume-poutre, avec un seul élément dans l’épaisseur des lamelles et un seul élément dans la section des goujons. Les résultats démontrent que les méthodes proposées dans cette thèse mènent à des outils de modélisation efficaces pour les structures multicouches en bois assemblées par des goujons en bois densifié. Ces méthodes ouvrent également de nouvelles pistes de développements futurs et des perspectives d’application à d’autres types de structures
Vicarious Evaluation of a Decision Model for Human-Agent Social Touch Interactions
No full textInternational audienceDownload citationReferences (37)AbstractIn this paper, we present a decision model aimed at determining when a social touch by a socially interactive agent (SIA) would be considered socially ‘correct’ : both coherent (meaningful given the current situation) and acceptable to the human interlocutor. Those decisions are computed by taking the context of interaction and the estimated level of rapport between the human and the agent into account. We then present a study based on a vicarious protocol where participants evaluated recorded interactions between an avatar (a human-controlled 3D character) and our agent. Results indicate that the estimations made by our decision model regarding the state of the situation mirror those made by human observers. Our initial hypothesis that the level of rapport would positively influence the acceptability of a touch receives mixed support. Social touch occurrences did not feel as coherent and acceptable as hoped yet. Avenues of improvement for human-agent interactions including social touch are discussed
Green Strategy for Sustainable Silk Lipopeptide Production using Mechanochemistry
No full textInternational audienceA mechanochemical approach to peptide N-acylation was used for silk sericin lipopeptide production. A one-pot, two-step method with 1,1′-carbonyldiimidazole (CDI) fatty acid activation, followed by acylation, was implemented. First, the procedure was optimized on model amino acids such as leucine, glycine, serine, and aspartic acid using two different types of ball mill equipment: a vibrational ball mill and a planetary ball mill. High conversion rates of 99% were observed for amino acid acylation under optimal conditions with both types. Then, grafting hydrophobic chains on to two different silk sericin hydrolysates was studied. The peptide acylation rate of 48–51% was obtained with three fatty acids with chain lengths of 10, 12, and 14. Lipopeptides obtained using the mechanochemical methodology showed good surface activity and reduced surface tension of up to 26 mN/m. The advantage of the proposed approach compared to conventional Schotten–Baumann N-acylation was confirmed with green metrics calculation
Mechanical properties of decellularized porcine esophagus: Preliminary results
No full textInternational audienceEsophageal tissue engineering is a promising approach to create an esophageal substitute after surgical resection of a part of the organ. Regeneration of esophageal tissue may be achieved using some synthetic or biological scaffolds. In the present study, scaffolds are obtained through the decellularization of porcine esophagi. In view of future implantation, it is important to test the mechanical properties of the decellularized matrices and to compare them with the data obtained for native pig esophagi. Results of longitudinal and circumferential traction experiments as well as inflation and burst tests are presented. The results obtained for the compliance of porcine decellularized matrices are novel. It is concluded that the decellularized matrices are suitable for use as esophageal substitutes.</div
Construction of fitted behavior laws from experimental data for muscle aging simulation
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Monitoring of Lung Stiffness for Long-COVID Patients Using Magnetic Resonance Elastography (MRE)
No full textInternational audiencePurpose: Transaxial CT imaging is the main clinical imaging modality for the assessment of COVID-induced lung damage. However, this type of data does not quantify the functional properties of the lung. The objective is to provide non-invasive personalized cartographies of lung stiffness for long-COVID patients using MR elastography (MRE) and follow-up the evolution of this quantitative mapping over time.Methods: Seven healthy and seven long-COVID participants underwent CT and MRE imaging at total lung capacity. After CT test, a senior radiologist visually analyzed the lung structure. Less than one month later, a first MRI (1.5 T, GRE sequence) lung density test followed by a first MRE (SE-EPI sequence) test were performed. Gadolinium-doped water phantom and a pneumatic driver (vibration frequency: 50 Hz), placed on the sternum, were used for MRI and MRE tests, respectively. Personalized cartographies of the stiffness were obtained, by two medical imaging engineers, using a specific post processing (MMDI algorithm). The monitoring (lung density, stiffness) was carried out no later than 11 months for each COVID patient. Wilcoxon's tests and an intra-class correlation coefficient (ICC) were used for statistical analysis.Results: The density for long-COVID patients was significantly (P = 0.047) greater (170 kg.m -3 ) compared to healthy (125 kg.m -3 ) subjects. After the first MRE test, the stiffness measured for the healthy subjects was in the same range (median value (interquartile range, IQR): 0.93 (0.09) kPa), while the long-COVID patients showed a larger stiffness range (from 1.39 kPa to 2.05 kPa). After a minimum delay of 5 months, the second MRE test showed a decrease of stiffness (from 22 % to 40 %) for every long-COVID patient. The inter-operator agreement was excellent (intra-class correlation coefficient: 0.93 [0.78 -0.97]).Conclusion: The MRE test is sensitive enough to monitor disease-induced change in lung stiffness (increase with COVID symptoms and decrease with recovery). This non-invasive modality could yield complementary information as a new imaging biomarker to follow up long-COVID patients
Estimation of the surface mechanical properties of soft tissues mimicking phantoms using impact analyses: a comparative study
No full textBouffandeau, A, Bensamoun, S, Schleip, R, Rosi, G, Flouzat-Lachaniette, CH, Meningaud, JP and Haiat G “Estimation of the surface mechanical properties of soft tissues mimicking phantoms using impact analyses: a comparative study” in press to IRBMInternational audienceBackground -Palpation is the most widely used approach to empirically assess the mechanical properties of superficial tissues. While elastography is used for volume measurements, it remains difficult to assess skin properties with non-invasive methods. This study aimed to compare the performances of an impact-based analysis method (IBAM) consisting in studying the dynamic response of a punch in contact with the tissue with other approaches available on the market.Materials and Methods -IBAM consists in analyzing the time dependent force signal induced when a hammer instrumented with a force sensor impacts a cylindrical punch placed in contact with soft tissue. Sensitivities to stiffness changes and to spatial variations were compared between IBAM and four other mechanical surface characterization techniques: IndentoPro® (macroindentation), Cutometer® (suction), MyotonPro® (damped oscillation) and Shore Durometer (durometry) using soft tissue phantoms based on polyurethane gel.Results -For stiffness discrimination in homogeneous phantoms, IBAM was slightly better than IndentoPro and MyotonPro (by 20 % and 35 % respectively), and outperformed the Shore Durometer and Cutometer by a factor of 2 to 4. Furthermore, for stiffness and thickness variations in bilayer phantoms, the axial sensitivity of IBAM was between 2.5 and 4.5 times better than that of MyotonPro and IndentoPro. In addition, the Cutometer appeared to be severely limited by its measurement depth. Conclusion -IBAM seems to be a promising technique for characterizing the mechanicalproperties of soft tissue phantoms at relatively low depth after future ex vivo and in vivo validation studies with biological tissues (with both animal and in human experiments). This work could pave the way to the development of a decision support system in the field of dermatology and cosmetics.</div