Evaluation of the kinetic and relaxation time of gentamicin sulfate released from hybrid biomaterial Bioglass-chitosan scaffolds

International audienceChitosan scaffolds, combined with bioactive glass 46S6, were prepared to serve as gentamicin sulfate delivery in situ systems for bone biomaterials. This work presents a study about the effect of the ratio chitosan/bioactive glass (CH/BG) on the release of gentamicin sulfate and on the bioactivity during in vitro experiments. SEM observations allowed understanding the bond between the glass grains and the chitosan matrix. In vitro results showed that scaffolds form a hydroxyapatite (HA) Ca10(PO4)6(OH)2 after 15 days of immersion in a simulated body fluid (SBF).The interest of this study is to see that the increase of the content of bioactive glass in the chitosan matrix slows the release of gentamicin sulfate in the liquid medium. Starting concentration of gentamicin sulfate has an influence on the relaxation time of the scaffolds. Indeed, an increasing concentration delays the return to a new equilibrium. Contents of chitosan and bioactive glass do not affect the relaxation time. Synthesized scaffolds could be adapted to a clinical situation: severity and type of infection, weight and age of the patient

Thermal investigations of Ti and Ag-​doped bioactive glasses

International audienceThe purpose of this paper is to explore the effect of titanium and silver on the characteristic temperatures of 46S6 glass and the excess entropy. The results show that the adding of these metals in the chemical composition does not affect the amorphous character of glasses. The introduction of these elements greatly reduces the melting temperatures of glasses and involves similar variations on the crystallization and glass transition temperatures. These elements also increase the thermal stability of glasses. The excess entropy calculations show a decrease when the content of Ti or Ag increases. Contrary to crystals, synthesized glasses have entropy different to zero at T = 0 K

Moldable multispectral glasses in GeS2–Ga2S3–CsCl system transparent from the visible up to the thermal infrared regions

International audienceThis work is based on the development of glasses with extremely wide optical transmission range for multispectral imaging (visible + thermal imaging for example) with the same optical system. Glass compns. based on the GeS2-​Ga2S3-​CsCl system have been selected in order to obtain glasses transparent from the visible up to the 8-​12 μm region. An increase of CsCl content can greatly improve the visible transmission of the glasses which however will be more sensitive to ambient moisture. Two glasses with different chromatic dispersion, necessary for the design of an optical system, are developed and characterized. Molding tests on aspheric surfaces demonstrate clearly the ability of these two glasses to be molded into complex optics without crystn. and with excellent roughness. In order to test the ability of an anti-​reflective coating to protect these glasses against the atm. aggression, a ZnS coating has been applied to these glasses. An effective protection can be achieved with a ZnS coating of less than 1 μm of thickness. These results allow considering the use of compns. with higher CsCl content if still more transparency in the visible region is desired

Molecular dynamics of glycerol and glycerol-trehalose bioprotectant solutions nanoconfined in porous silicon

Glycerol and trehalose-glycerol binary solutions are glass-forming liquids with remarkable bioprotectant properties. Incoherent quasielastic neutron scattering (QENS) is used to reveal the different effects of nanoconfinement and addition of trehalose on the molecular dynamics in the normal liquid and supercooled liquid phases, on a nanosecond timescale. Confinement has been realized in straight channels of diameter D=8 nm formed by porous silicon. It leads to a faster and more inhomogeneous relaxation dynamics deep in the liquid phase. This confinement effect remains at lower temperature where it affects the glassy dynamics. The glass transitions of the confined systems are shifted to low temperature with respect to the bulk ones. Adding trehalose tends to slow down the overall glassy dynamics and increases the non-exponential character of the structural relaxation. Unprecedented results are obtained for the binary bioprotectant solution, which exhibits an extremely non-Debye relaxation dynamics as a result of the combination of the effects of confinement and mixing of two constituents

Influence of Upconversion Processes in the Optically-Induced Inhomogeneous Thermal Behavior of Erbium-Doped Lanthanum Oxysulfide Powders

The efficient infrared-to-visible upconversion emission present in Er-doped lanthanum oxysulfide crystal powders is used as a fine thermal sensor to determine the influence of upconversion processes on the laser-induced thermal load produced by the pump laser and to assess the potentialities of this material in order to obtain anti-Stokes laser-induced cooling. The analysis of the upconversion emission and excitation spectra as well as the decay curves indicates that energy transfer upconversion is the main mechanism responsible for the green (S-4(3/2)) and red (F-4(9/2)) upconversion luminescence. The dependence on temperature of the intensity ratio of upconversion emission from thermally-coupled H-2(11/2) and S-4(3/2) levels of Er3+ in the 240-300 K temperature range has been used to estimate a relative sensitivity of 1.09 x 10(-2) K-1. Thermal measurements performed on the powder samples by using a thermal infrared camera exhibit a very inhomogeneous heat distribution at the sample surface due to the random distribution of the pumping energy inside the sample as well as to the random properties of the thermal field. The analysis of both spectroscopic and thermal measurements show that after a transient heating induced by the background absorption, cooling of discrete regions by means of anti-Stokes processes can be observed.This work was supported by the Spanish Government under project MAT2013-48246-C2-2-P and Basque Country Government IT-943-16. Macarena Barredo-Zuriarrain acknowledges an FPI grant from the Spanish Government

Sample preparation for an optimized extraction of localized metabolites in lichens: Application to Pseudevernia furfuracea

International audienceLichens are symbiotic organisms known for producing unique secondary metabolites with attractive cosmetic and pharmacological properties. In this paper, we investigated three standard methods of preparation of Pseudevernia furfuracea (blender grinding, ball milling, pestle and mortar). The materials obtained were characterized by electronic microscopy, nitrogen adsorption and compared from the point of view of extraction. Their microscopic structure is related to extraction efficiency. In addition, it is shown using thalline reactions and mass spectrometry mapping (TOF-SIMS) that these metabolites are not evenly distributed throughout the organism. Particularly, atranorin (a secondary metabolite of interest) is mainly present in the cortex of Pseudevernia furfuracea. Finally, using microwave assisted extraction (MAE) we obtained evidence that an appropriate preparation can increase the extraction efficiency of atranorin by a factor of fiv

Zinc-gallium oxynitride powders: effect of the oxide precursor synthesis route

International audienceZinc-gallium oxynitride powders (ZnGaON) were synthesized by nitridation of ZnGa2O4 oxide precursor obtained by polymeric precursors (PP) and solid state reaction (SSR) methods and the influence of the synthesis route of ZnGa2O4 on the final compound ZnGaON was investigated. Crystalline single phase ZnGa2O4 was obtained at 1100 oC / 12 h by SSR and at 600 oC / 2 h by PP with different grain sizes and specific surface areas according to the synthesis route. After nitridation, ZnGaON oxynitrides with a GaN würtzite-type structure were obtained in both cases, however at lower temperatures for PP samples. The microstructure and the specific surface area were strongly dependent on the oxide synthesis method and on the nitridation temperature (42 m2g-1 and 5 m2g-1 for PP and SSR oxides treated at 700 °C, respectively). The composition analyses showed a strong loss of Zn for the PP samples, favored by the increase of ammonolysis temperature and by the higher specific surface area

Various Statistical Approaches to Assess and Predict Carcass and Meat Quality Traits

Publication history: Accepted - 8 April 2020; Published - 22 April 2020.The beef industry is organized around di erent stakeholders, each with their own expectations, sometimes antagonistic. This article first outlines these di ering perspectives. Then, various optimization models that might integrate all these expectations are described. The final goal is to define practices that could increase value for animal production, carcasses and meat whilst simultaneously meeting the main expectations of the beef industry. Di erent models previously developed worldwide are proposed here. Two new computational methodologies that allow the simultaneous selection of the best regression models and the most interesting covariates to predict carcass and/or meat quality are developed. Then, a method of variable clustering is explained that is accurate in evaluating the interrelationships between di erent parameters of interest. Finally, some principles for the management of quality trade-o s are presented and the Meat Standards Australia model is discussed. The “Pareto front” is an interesting approach to deal jointly with the di erent sets of expectations and to propose a method that could optimize all expectations togethe

La race a-t-elle un effet sur la qualité sensorielle de la viande de jeune bovin?

Dans le cadre du consortium européen Gemqual, 436 jeunes bovins issus de 15 races bovines différentes ont été conduits dans des systèmes d'élevage similaires afin d'évaluer l'impact de la race sur la qualité organoleptique de la viande déterminée par analyse sensorielle. Une comparaison de deux méthodes statistiques pour traiter les données de l'analyse sensorielle a tout d'abord été réalisée. L'analyse de variance avec ou sans effet dégustateur a abouti à des résultats similaires indiquant que ce choix méthodologique n'est pas décisif pour l'interprétation des résultats. Une classification non supervisée (classification ascendante hiérarchique) a ensuite permis de classer les races en fonction de trois profils sensoriels sur la base de 4 descripteurs (tendreté, jutosité, intensité de flaveur et flaveur anormale). Elle permet de mettre en évidence 5 associations de races. : Les races Aberdeen Angus, Highland et Jersey, qui ont une teneur élevée en lipides dans le muscle étudié (Longissimus thoracis), se sont distinguées des autres races par une flaveur de bœuf plus élevée. Les races mixtes et rustiques, Simmental, Casina et Marchigiana, ont produit une viande significativement moins juteuse et moins tendre que celle des races sélectionnées pour la production de viande. Les trois autres associations suivantes rassemblent les races Limousine et Charolaise dont le profil semble assez proche, les races Pirenaica et Avilena tendres et fortement appréciées par les panélistes, les races Asturiana de los Valles et Piemontaise caractérisées par une flaveur anormale plus intense. Dans l'ensemble, malgré des différences significatives de caractéristiques de l'animal, de la carcasse et du muscle, les différences de qualité sensorielle entre la plupart des races étaient faibles, avec seulement des différences significatives entre les quelques races qui présentaient des profils sensoriels extrêmes (comme la Simmental et la Pirenaica).PublishedCet article correspond à une étude publiée dans Livestock Science 250 (2021) 104548. Elle démontre qu’il existe peu de différences de qualité sensorielle entre races bovines bien que les races rustiques ou mixtes tendent à produire une viande légèrement moins tendre et moins juteuse et les races les plus grasses une viande avec plus de goû