Lignin‐derived hard carbon anode with a robust solid electrolyte interphase for boosted sodium storage performance

Hard carbon is regarded as a promising anode candidate for sodium-ion batteries due to its low cost, relatively low working voltage, and satisfactory specific capacity. However, it still remains a challenge to obtain a high-performance hard carbon anode from cost-effective carbon sources. In addition, the solid electrolyte interphase (SEI) is subjected to continuous rupture during battery cycling, leading to fast capacity decay. Herein, a lignin-based hard carbon with robust SEI is developed to address these issues, effectively killing two birds with one stone. An innovative gas-phase removal-assisted aqueous washing strategy is developed to remove excessive sodium in the precursor to upcycle industrial lignin into high-value hard carbon, which demonstrated an ultrahigh sodium storage capacity of 359 mAh g−1. It is found that the residual sodium components from lignin on hard carbon act as active sites that controllably regulate the composition and morphology of SEI and guide homogeneous SEI growth by a near-shore aggregation mechanism to form thin, dense, and organic-rich SEI. Benefiting from these merits, the as-developed SEI shows fast Na+ transfer at the interphases and enhanced structural stability, thus preventing SEI rupture and reformation, and ultimately leading to a comprehensive improvement in sodium storage performance

Complexes multifonctionnel à base de chitosane pour la nanomédecine

Ce travail est consacré à l'élaboration de nano-complexes polyélectrolytes (CPEs) ayant une stabilité améliorée en milieux physiologiques et à l'exemplification de leur fort potentiel d'application comme système de délivrance de (macro) molécules bioactives. Le chitosane comme polycation a été compléxé avec quatre polyanions naturels ayant différents densités de charges et groupements fonctionnels(-COO- et SO3-) à savoir l'acide hyaluronique (HYA), le chondroïtine sulfate (ChonS), le sulfate de dextrane (DS) et l'héparine (HEP). Les facteurs qui influent sur la formation et les propriétés physico-chimiques des nano-complexes chitosane-HYA ont été étudiés. Ces nanovecteurs perdent leur caractère colloïdal en milieux physiologiques. Pour améliorer leur stabilité dans ces conditions, une stratégie innovante qui implique l'ajout de zinc a été conçue. Cette stratégie de stabilisation a été démontrée comme étant polyvalente et a été étendue aux complexes polyélectrolytes (CPEs) chitosane-ChonS. Même si de cette manière une stabilité à long terme a été observée, cette stratégie reste uniquement applicable aux CPEs cationiques. Pour cette raison, une approche alternative permettant l'amélioration de la stabilité des colloïdes à charges positives ou négatives a été mise en oeuvre en concevant des nano-complexes de type coeur-couronne ternaires composés de polyacides forts c'est-à-dire de DS ou d'HEP associés au chitosane en coeur et un complexe chitosane-HYA en couronne. Tous les nano-complexes stables obtenus peuvent encapsuler le ténofovir, une molécule antirétrovirale et être fonctionnalisés par des IgAs de ciblage. En in vitro, ces nanovecteurs montrent une inhibition de l'infection des PBMC par le virus VIH-1 supérieure à l'antirétrovirale seuleThis work is devoted to the elaboration of nano-polyelectrolyte complexes (PECs) systems with improved stability in physiological media and to the establishment of their high potential of applications as bioactive (macro) molecule delivery systems. Chitosan as polycation were complexed with four natural polyanions of different charged groups and densities (-COO- and SO3 - as negative charges), namely hyaluronan (HYA), chondroitin sulfate (ChonS), dextran sulfate (DS) and heparin (HEP). The factors impacting the formation and physical-chemical properties of chitosan-HYA nanocomplexes were investigated. However, these nanovectors lost their colloidal character in physiological media. To improve their colloidal stability in physiological conditions, an innovative stabilization strategy was designed, involving zinc ion. This stabilization strategy proved versatile and was extended to chitosan-ChonS PECs. Though a long-term stability was achieved, this strategy was only applicable to cationic PECs. Therefore, an alternate approach enabled the improvement of the colloidal stability in physiological media of both positive and negative colloids by designing core-shell ternary polyelectrolyte nanocomplexes composed of strong polyacid (DS or HEP)-chitosan PECs as core and a chitosan-HYA complex as shell. Furthermore, all of the stabilized nanocomplexes allowed the encapsulation of active molecules anti-retroviral drug tenofovir and surface functionalization with targeting IgAs. In vitro, these nanovectors exhibited an inhibition of infection of PBMCs by HIV-1 virus which could be superior to the free dru

Equitable Coloring of IC-Planar Graphs with Girth g ≥ 7

An equitable k-coloring of a graph G is a proper vertex coloring such that the size of any two color classes differ at most 1. If there is an equitable k-coloring of G, then the graph G is said to be equitably k-colorable. A 1-planar graph is a graph that can be embedded in the Euclidean plane such that each edge can be crossed by other edges at most once. An IC-planar graph is a 1-planar graph with distinct end vertices of any two crossings. In this paper, we will prove that every IC-planar graph with girth g≥7 is equitably Δ(G)-colorable, where Δ(G) is the maximum degree of G

Stabilization of chitosan/hyaluronan colloidal polyelectrolyte complexes in physiological conditions

International audiencePolyelectrolyte complexes (PECs) between hyaluronan (HYA) and chitosan were obtained by the one-shot addition of default amounts of polyanion to an excess of polycation. The impact of intrinsic parameters (degree of polymerization and degree of acetylation) and extrinsic parameters (charge mixing ratio, the concentration and pH of polyelectrolyte solutions) on particle sizes and polydispersity were investigated. The PECs maintained their colloidal stability when stored in water. To preserve the colloidal stability at physiological salt concentration and pH, biological nontoxic metallic Zn(II) was added either post or during the formation of the particles. Dynamic light scattering results showed the PEC particle sizes in phosphate buffer saline remained constant and displayed a good stability at room temperature for at least 35 days, irrespective of the stabilization process by Zn(II). These results open promising prospects for the zinc cation stabilized chitosan HYA PECs as efficient and safe tools for drug delivery

Probiotic <i>Escherichia coli</i> NISSLE 1917 for inflammatory bowel disease applications

Probiotic Escherichia coli Nissle 1917 (EcN) with different modifications has exhibited multiple superiorities in the prevention and treatment of inflammatory bowel disease.</jats:p