Structure of the high voltage phase of layered P2-Na_(2/3−z)[Mn_(1/2)Fe_(1/2)]O_2 and the positive effect of Ni substitution on its stability

A combination of operando X-ray diffraction, pair distribution function (PDF) analysis coupled with electrochemical measurements and Mössbauer spectroscopy elucidates the nature of the phase transitions induced by insertion and extraction of sodium ions in P2-Na_(0.67)[Ni_yMn_(0.5+y)Fe_(0.5−2y)]O_2 (y = 0, 0.10, 0.15). When phase transitions are avoided, the optimal cathode material – P2-Na_(0.67)Fe_(0.2)Mn_(0.65)Ni_(0.15)O_2 – delivers 25% more energy than the unsubstituted material, sustaining high specific energy (350 Wh kg^(−1)) at moderate rates and maintains 80% of the original energy density after 150 cycles – a significant improvement in performance vs. the unsubstituted analogue. The crystal structure of the high voltage phase is solved for the first time by X-ray PDF analysis of P2-Na_(0.67−z)Fe_(0.5)Mn_(0.5)O_2 (where z ∼ 0.5), revealing that migration of the transition metals – particularly Fe^(3+) – into tetrahedral sites in the interlayer space occurs at high potential. This results in new short range order between two adjacent layers. Although the transition metal migration is reversible as proven by electrochemical performance, it induces a large disfavourable cell polarization. The deleterious high voltage transition is mitigated by substitution of Fe^(3+) by Mn^(4+)/Ni^(2+), giving rise to better cycling performance. Moreover, as demonstrated by ^(57)Fe Mössbauer spectroscopy, the much lower ratio of Fe^(4+)O_6 to Fe^(3+)O_6 observed systematically across the range of Ni content – compared to the values expected from a purely ionic model – suggests redox activity involves the O-2p orbitals owing to their overlap with the transition metal-3d orbitals

In Vivo Downregulation of Innate and Adaptive Immune Responses in Corneal Allograft Rejection by HC-HA/PTX3 Complex Purified From Amniotic Membrane

Citation: He H, Tan Y, Duffort S, Perez VL, Tseng SCG. In vivo downregulation of innate and adaptive immune responses in corneal allograft rejection by HC-HA/PTX3 complex purified from amniotic membrane. Invest Ophthalmol Vis Sci. 2014;55:164755: -165655: . DOI:10.1167 PURPOSE. Heavy chain-hyaluronic acid (HC-HA)/PTX3 purified from human amniotic membrane (AM) was previously observed to suppress inflammatory responses in vitro. We now examine whether HC-HA/PTX3 is able to exert a similar effect in vivo, using murine models for keratitis and corneal allograft rejection. METHODS. The in vitro effect of HC-HA/PTX3 was tested using OTII ovalbumin (OVA) transgenic, purified CD4 þ T cells, or IFN-c/lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Cytokine production was measured by ELISA, while cell surface markers and cell proliferation were determined by flow cytometry. In vivo effects of HC-HA/PTX3 were analyzed by quantifying the recruitment of enhanced green fluorescence-labeled macrophages and by measuring the expression of arginase 1 (Arg-1), IL-10, and IL-12 in LPS-induced keratitis in the macrophage Fas-induced apoptosis (Mafia) mouse. The effect of corneal allograft survival in a complete major histocompatibility complex (MHC) mismatched mouse model was assessed by grading corneal opacification. RESULTS. In vitro studies demonstrated that HC-HA/PTX3 significantly enhanced the expansion of FOXP3 T cells and suppressed cell proliferation and protein expression of IFN-c, IL-2, CD25, and CD69 in activated CD4 þ T cells. Furthermore, immobilized HC-HA/PTX3 significantly upregulated IL-10 gene expression but downregulated that of IL-12 and IL-23 in activated RAW264.7 cells. Finally, in vivo subconjunctival injection of HC-HA/PTX3 significantly prolonged corneal allograft survival, suppressed macrophage infiltration, and promoted M2 polarization by upregulating Arg-1 and IL-10 but downregulating IL-12. CONCLUSIONS. HC-HA/PTX3 can suppress inflammatory responses in vivo by modulating both innate and adaptive immunity of macrophages and CD4 þ T cells

A Targeted and Adjuvanted Nanocarrier Lowers the Effective Dose of Liposomal Amphotericin B and Enhances Adaptive Immunity in Murine Cutaneous Leishmaniasis

Background: Amphotericin B (AmB), the most effective drug against leishmaniasis, has serious toxicity. As Leishmania species are obligate intracellular parasites of antigen presenting cells (APC), an immunopotentiating APC-specific AmB nanocarrier would be ideally suited to reduce the drug dosage and regimen requirements in leishmaniasis treatment. Here, we report a nanocarrier that results in effective treatment shortening of cutaneous leishmaniasis in a mouse model, while also enhancing L. major specific T-cell immune responses in the infected host. Methods: We used a Pan-DR-binding epitope (PADRE)-derivatized-dendrimer (PDD), complexed with liposomal amphotericin B (LAmB) in an L. major mouse model and analyzed the therapeutic efficacy of low-dose PDD/ LAmB vs full dose LAmB. Results: PDD was shown to escort LAmB to APCs in vivo, enhanced the drug efficacy by 83% and drug APC targeting by 10-fold and significantly reduced parasite burden and toxicity. Fortuitously, the PDD immunopotentiating effect significantly enhanced parasite-specific T-cell responses in immunocompetent infected mice. Conclusions: PDD reduced the effective dose and toxicity of LAmB and resulted in elicitation of strong parasite specific T-cell responses. A reduced effective therapeutic dose was achieved by selective LAmB delivery to APC, bypassing bystander cells, reducing toxicity and inducing antiparasite immunity

Infiltration of Proinflammatory M1 Macrophages into the Outer Retina Precedes Damage in a Mouse Model of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a major cause of blindness in the developed world. Oxidative stress and inflammation are implicated in AMD, but precise mechanisms remain poorly defined. Carboxyethylpyrrole (CEP) is an AMD-associated lipid peroxidation product. We previously demonstrated that mice immunized with CEP-modified albumin developed AMD-like degenerative changes in the outer retina. Here, we examined the kinetics of lesion development in immunized mice and the presence of macrophages within the interphotoreceptor matrix (IPM), between the retinal pigment epithelium and photoreceptor outer segments. We observed a significant and time-dependent increase in the number of macrophages in immunized mice relative to young age-matched controls prior to overt pathology. These changes were more pronounced in BALB/c mice than in C57BL/6 mice. Importantly, IPM-infiltrating macrophages were polarized toward the M1 phenotype but only in immunized mice. Moreover, when Ccr2-deficient mice were immunized, macrophages were not present in the IPM and no retinal lesions were observed, suggesting a deleterious role for these cells in our model. This work provides mechanistic evidence linking immune responses against oxidative damage with the presence of proinflammatory macrophages at sites of future AMD and experimentally demonstrates that manipulating immunity may be a target for modulating the development of AMD

Implementation of PDF analysis using a silver microfocus source and its application to the structure resolution of turbostractic sodium layered oxides

International audienc

Fundamentals and current research trends in Solid Oxides Cells for energy production and conversion

National audienc

Structure and transport properties of a new bismuth chromate

International audienc

Contrôle de la stoechiométrie en oxygène dans les oxydes "114" de type LnBaFe4O7+d (structure et magnétisme)

Ce travail de thèse est axé sur la caractérisation des propriétés chimiques, structurales et physiques d une nouvelle famille d oxyde de fer de formule LnBa(Fe,M)4O7+ . Ces oxydes, appartenant la famille grandissante des composés dits 114 , possèdent un type structural basé sur la symétrie cubique des 114 , contrairement aux composés à base de cobalt. La description de leur réactivité vis-à-vis de l oxygène, notamment à température ambiante avec le dioxygène de l air, nous a conduit à porter une attention particulière à la caractérisation de la quantité d oxygène excédentaire . Cette approche nous a permis de stabiliser de nouvelles structures pour les composés stœchiométriques LnBaFe4O7.0 ( = 0) avec Ln = Y, Dy-Lu. L étude de ces nouvelles structures à rendu possible la compréhension des phénomènes gouvernant l évolution des propriétés magnétiques et de transport dans cette famille de composés. Nous avons montré grâce à la synthèse de compositions originales, en substituant des atomes de fer par du manganèse, que les capacités d absorption de l oxygène pouvaient être contrôlées par la nature des substituants. Enfin l étude des composés CaBaFe4O7+ et CaBaCo4O7+ à permis de préparer par électrochimie des phases oxydées métastables présentant des propriétés magnétiques originales.This works is based on the characterization of the chemical, structural and physical properties of a new family of iron oxides with the formula LnBa(Fe,M)4O7+ . These oxides, belonging to the growing family of 114 oxides, are based on a cubic cell, conversely to the cobalt containing 114 oxides which crystallized in a hexagonal cell. The description of their reactivity with oxygen, has led us to consider the oxygen excess, . This approach has enable us to stabilize new structures for the stoichiometric compound LnBaFe4O7.0 ( = 0) for Ln = Y, Dy-Lu. The study of these new structures has given opportunity to understand the mechanisms that are governing the trends of the magnetic and transport properties. The synthesis of original compositions, substituting manganese for iron, has led to a significant increase of the oxygen absorption properties. Finally, investigations on CaBaFe4O7+ and CaBaCo4O7+ have allowed us, using electrochemical oxidation methods, to prepare oxidized metastable phases with interesting magnetic properties.CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Gd0.1Ce0.9O1.95/Er0.5Bi1.5O3 bilayered electrolytes fabrication and characterization for LT-SOFC

International audienc

Fabrication of bilayered electrolyte ESB/GDC for low temperatures solid oxide fuel cells

National audienceSolid Oxide Fuel Cells are electrochemical devices that convert the chemical energy contained in a fuel/oxidizer pair, generally H2/O2, into electrical energy. They received a great deal of attention due to their high electrical efficiency (60%), durability, low cost and flexibility in the choice of fuel.1 The main specificity of SOFCs is a high operating temperature between 700 °C and 1000 °C, dictated by the ionic conduction of yttrium stabilized zirconia (YSZ), the reference electrolyte. A recent study showed that a bi-layer electrolyte based on stabilized bismuth oxide and stabilized ceria has led to a significant improvement with a specific power density of ~1 W.cm-2 at 650 °C. 2 In 2013, devices capable of operating at 550 °C were even marketed, thus opening up new perspectives for ionic conductors derived from bismuth oxide, widely studied at UCCS 20 years ago. These materials present ionic conductivities several order of magnitude higher than YSZ but have been neglected in recent years due to their instability in a reducing atmosphere. As part of the BIBELOT grant (ANR-18-CE05-0001), which aims at finding new cathode materials for this type of device, we initially considered the development of a two-layer electrolyte Er0.5Bi1.5O3/ Gd0.1Ce0.9O1.95 (ESB/GDC). For the fabrication and deposition of the ESB on GDC, the ESB powder was synthesized at temperatures as low as 500 °C using wet chemical co-precipitation and sol-gel procedure in order to minimize the grain size and therefore obtain a dense ESB layer. We will present here the first results obtained by spin coating on a dense electrolyte of GDC of an ink prepared from this ESB powder. AcknowledgementCNRS, Ministère de l'Enseignement Supérieur et de la Recherche and Agence Nationale de la Recherche and BIBELOT ANR-18-CE05-0001 are acknowledged for funding.References[1] D. M. Bierschenk, J. R. Wilson and S. A. Barnett, Energy Environ. Sci., 2011, 4, 944–951.[2] E.D. Wachsman, K.T. Lee, Science, 334 (2011), 935-939