THE SYNTHESIS AND CHARACTERIZATION OF DUAL-MODIFIED CARBOXYMETHYLCELLULOSE FOR BIOADHESIVE APPLICATIONS

Reparative medical techniques, in conjunction with existing and emerging tissue adherents and sealants, offer practicing physicians a wide variety of tools to improve the functionality, performance, and safety of surgical interventions. Carboxymethylcellulose (CMC) is a plant-derived polymer that is cytocompatible, biocompatible, biodegradable, and inexpensive. The need for a non-toxic but strongly adherent material motivated the development of an injectable bioadhesive system containing CMC modified with functional methacrylate and aldehyde groups that could potentially be used as an annulus fibrosus sealant or as a supplement to existing wound closure materials. After modification, the polymer was characterized via NMR spectroscopy, Schiff’s base reaction, and size exclusion chromatography with multi-angle light scattering (SEC-MALS). The adhesive strength of the material was determined by lap shear testing with porcine skin. High molecular weight and medium molecular weight methacrylated dialdehyde carboxymethylcellulose (MeDCMCHV & MeDCMCMV) were engineered and MeDCMCHV was combined with low viscosity methacrylated CMC (MeCMCLV1) to produce an adhesive hydrogel. The percent oxidation and methacrylation was measured to be 21.1 ± .84 % and 49.0% for MeDCMCHV2. The percent methacrylation of MeCMCLV1 was determined to be 30.6%. Various ratios of MeDCMCHV to MeCMCLV were tested via lap shear testing and the best combination possessed a shear adhesive strength of 6.022 ± 1.456 kPa. The dispersity index (Đ) was calculated to be 1.93 for MeDCMCHV and 2.94 for MeDCMCMV. The creation of an adhesive from MeDCMCHV will provide a foundation for the development of cellulose-based annulus fibrosus sealant with stronger adhesive strength and highly tunable properties such as swelling-ratio, pore size, and degradation profile

Nano-scale modeling and elastic properties of a typical CSH (I) structure based on DFT and Molecular Dynamics Methods

International audience Les silicates de calcium hydratés (C-S-H) sont les constituants principaux de la pâte de ciment et ont donc une grande influence sur les propriétés mécaniques des matériaux cimentaires. Le modèle de tobermorite-11Å (formule chimique: Ca4Si6O14(OH)4•2H2O) est d'abord considéré comme configuration initiale pour décrire ces hydrates. Ce modèle est alors étudié par DFT (Density Functional Theory) et Dynamique Moléculaire. Les constantes élastiques sont calculées et comparées à des valeurs expérimentales. Un Silicate de Calcium Hydraté amorphe est obtenu par le biais d'une modélisation par Dynamique Moléculaire d'un processus de recuit de la tobermorite-11Å avec utilisation d'un potentiel de Born-Huggins-Meyer (BMH). Des tests uniaxiaux de traction et de compression d'un silicate de calcium hydraté amorphe (avec un rapport Ca/Si de 0,67), à une certaine vitesse de déformation, sont modélisés. Les courbes contrainte-déformation sont analysées. Les résultats montrent que: (1) les coefficients élastiques Cij sont obtenus dans la plage de pression de confinement 0-1GPa pour vérifier la fiabilité du modèle par comparaison avec des résultats de la littérature. (2) Un modèle de super-cellule à l'échelle nano montre des propriétés mécaniques isotropes (3) Après recuit pour obtenir un C-S-H (I) amorphe, le module de Young est en moyenne d'environ 21,4 GPa. </div

The influence of aggregate shape, volume fraction and segregationon the performance of Self-Compacting Concrete :3D modeling and simulation

International audienc

Brain, language, and handedness: a family affair

The left planum temporale is a marker of left hemisphere language specialization. We investigated the effect of individual handedness and familial sinistrality on left planum temporale surface area and found the size is reduced in proportion with the number of left-handed immediate family members and is lowest when one&#x27;s mother is left-handed. This reduction is independent of an individual&#x27;s handedness or sex and has no counterpart in the right hemisphere

The Effect of Thermal Contact Conductance (TCC) Between Aggregate Inclusion and Matrix on Thermal Conductivity of Cement-Based Material

The effect of Thermal Contact Conductance (TCC) on thermal conductivity of mortar has been studied at the interface between the limestone and cement paste. A novel methodology, which involves the use of Scanning Electron Microscope (SEM) to scan the image of the interface in mortar, the software PlotDigitizer to create a set of points of the interface, and the FE software Abaqus/CAE to perform heat transfer simulation, is proposed in this study. Moreover, several hypotheses at the interface such as the gaps, flaws, and Interfacial Transition Zone (ITZ) are also highlighted. Temperature drop, thermal conductivity, and the TCC coefficient has been calculated for each model in order to understand the effect of TCC on cement-based materials thermal properties. The results show that the temperature drops at the interface are very low and the TCC coefficients are very high so that it can be ignored in heat transfer simulation except for a large air gap at the interface. Thus, it can be concluded that the TCC has no influence on the thermal conductivity of mortar