Platelet phospholipids are differentially protected against oxidative degradation by plasmalogens

The oxidative degradation of phospholipids in the presence and absence of plasmalogens (plasmenyl phosphatidylethanolamine: PPE) was followed by chemical analysis. Human platelet phospholipids, either intact or after removal of PPE by acid treatment, were oxidized with 28 mM 2,2′-azobis(2-amidinopropane di-HCl in Triton X-100 micelles (detergent/phospholipid 5∶1, mol/mol). PPE (12% of all phospholipids, mol/mol) disappeared about three times more rapidly than glycerophospholipids, whereas sphingomyelin remained unaltered and the lysophosphatidylethanolamine (lysoPE) generated became progressively more unsaturated. After 60 min oxidation, the FA compositions of PS, PC, and PI were similar in extracts with or without plasmalogens. In contrast, diacyl phosphatidylethanolamine (DPE) became more saturated in the absence of PPE. The rate of phospholipid destruction was always unique to each class, but for all phospholipids slowed down in the presence of PPE. This protective effect increased in the order DPE<PS<PC<PI and did not seem to be simply related to the class unsaturation. α-Tocopherol had no influence on the time courses of the quantities and compositions of the phospholipids, even at a molar ratio of α-tocopherol to phospholipids four times higher than in platelet membranes. Thus, PPE protected phospholipids efficiently but differentially against peroxidative attack, whereas the contribution of α-tocopherol appeared to be negligible even at a concentration four times greater than in platelet membranes.     

Hardness, Toughness, and Scratchability of Germanium–Selenium Chalcogenide Glasses

Ge–Se chalcogenide glasses are characterized by relatively low hardness (0.39–2.35 GPa) and low fracture toughness (0.1–0.28 MPa·m^1/2). Actually, the hardness of chalcogen-rich glasses is low enough so that the brittleness parameter, B = H / K _c , is lower than that of silicate glasses. Whereas hardness and Young's modulus increase with increasing germanium contents, fracture toughness follows a trend similar to that of the density and exhibits a maximum for the Ge₂₀Se₈₀ composition, which corresponds to the rigidity percolation threshold. Optical microscopy and atomic force microscopy observations suggest that the indentation deformation proceeds by a localized shear deformation phenomenon. Glasses in the chalcogen-rich region behave viscoelastically at room temperature. As a consequence, an increase of the loading time results in a decrease of hardness and toughness.     

Influence of Alumina-Supported M–Pt Catalysts in DeNOx Reactions with M = Pd or Ir or Ru

To better understand N₂ formation in the selective catalytic reduction of NO _x by propene under oxidative atmosphere, we studied the catalytic behavior of bimetallics. Surface segregation phenomena may provoke geometric and electronic modifications of the catalytic active sites. To explain our results we invoked: (i) the facile way to oxidize the bimetallic aggregates, (ii) the presence of atoms with low coordination number able to be oxidized first and (iii) an eventual formation of like vic-diNO _x species on such bimetallics leading to N₂ formation.     

Nuclear magnetic resonance characterization of high- and ultrahigh-performance concrete: Application to the study of water leaching

In the present study, we show that high-resolution ²⁹Si and ²⁷Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) can be a powerful tool for analyzing actual concrete mixes. The influence of the amount of silica fume and of the type of cement in high-performance concrete (HPC), as well as the influence of the type of silica fume and of the granular packing in ultrahigh-performance concrete (UHPC) were investigated. Significant effects on the amount and shape of C-S-H, on the incorporation of aluminum in the C-S-H structure, and on the distribution of aluminum-containing hydrates were observed. Nuclear magnetic relaxation of protons was also performed and it showed the fractal feature of the pore size distribution in UHPC and the higher amount of larger pores in HPC. The microstructure of the surface of these same formulations leached by mineral water for up to 1 year exhibits slight modifications.     

Tribological behavior of composites fabricated by reactive SPS sintering in Ti-Si-C system

In this study, wear and friction behavior of two based-composites from the Ti-Si-C system, (40 wt% TiC; 28 wt% Ti₅Si₃; 17 wt% Ti₃SiC₂) and (18 wt% TiC; 26 wt% Ti₅Si₃; 41 wt% Ti₃SiC₂) reinforced by 15 wt% of large size SiC (100-150 µm) particles were investigated. The four-phase composites exhibited approximatively the same friction coefficient (µ ~ 0.9) under high loads (10 N and 7 N). The composite with high Ti₃SiC₂ showed higher wear rate values by one order of magnitude. However, under 1 N, the composite with high TiC content showed a higher running-in period and a lower steady state µ value (0.37 after 1000 m sliding distance). Scanning electron microscopy, Energy Dispersive X-Ray and Raman spectroscopy analysis of the worn surfaces of the two composites revealed that oxidation was the dominant wear mechanism. The oxidation process and the removal kinetics of the oxides during sliding controlled the tribological behavior of the composites. The influence of processing variables on microstructures development and wear mechanisms of the composites is discussed.     

Modified Galacto- or Fuco-Clusters Exploiting the Siderophore Pathway to Inhibit the LecA- or LecB-Associated Virulence of Pseudomonas aeruginosa

Galacto- and fuco-clusters conjugated with one to three catechol or hydroxamate motifs were synthesised to target LecA and LecB lectins of Pseudomonas aeruginosa (PA) localised in the outer membrane and inside the bacterium. The resulting glycocluster–pseudosiderophore conjugates were evaluated as Trojan horses to cross the outer membrane of PA by iron transport. The data suggest that glycoclusters with catechol moieties are able to hijack the iron transport, whereas those with hydroxamates showed strong nonspecific interactions. Mono- and tricatechol galactoclusters ( G1C and G3C ) were evaluated as inhibitors of infection by PA in comparison with the free galactocluster ( G0 ). All of them exhibited an inhibitory effect between 46 to 75 % at 100 μM, with a higher potency than G0 . This result shows that LecA localised in the outer membrane of PA is involved in the infection mechanism.     

Iridium complexes incorporating coumarin moiety as catalyst photoinitiators: Towards household green LED bulb and halogen lamp irradiation

Household LED bulbs and halogen lamps are used to promote the ring-opening photopolymerization of epoxides in the presence of a new series of iridium(III) complexes (IrCs) exhibiting enhanced visible light absorption properties through the introduction of a coumarin moiety. These latter complexes are used as catalyst photoinitiators in an oxidative cycle in combination with a silane and an iodonium salt. Remarkably, even under the selected very soft irradiations (e.g. light intensity lower than 2 mW/cm²), excellent polymerization profiles are obtained (conversions > 80%). The mechanisms are investigated by ESR and luminescence experiments.     

Densification of alumina by SPS and HP: A comparative study

In this study, the densification of alumina by spark plasma sintering (SPS) was investigated and compared to conventional hot pressing. It was shown that SPS is very effective in the sintering of alumina leading to higher densities and allows to work at lower temperatures and with shorter sintering cycles. The effect of the heating rate is dependent on the heating mode (SPS or HP). The identification of active sintering mechanisms was attempted by an isothermal and an anisothermal methods, showing that other mechanisms probably related to electrical effects enhance the densification. We suggest the higher contribution of surface diffusion mainly during the initial stage of sintering and an influence of the presence of impurities segregated at the grain boundaries. They could create conductive layers and also introduce ions with a lower valence than Al³⁺; defects are created in the surface layers and the diffusion of the species is increased.     

Adventitial Tertiary Lymphoid Organs as Potential Source of MicroRNA Biomarkers for Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is an inflammatory disease associated with marked changes in the cellular composition of the aortic wall. This study aims to identify microRNA (miRNA) expression in aneurysmal inflammatory cells isolated by laser microdissection from human tissue samples. The distribution of inflammatory cells (neutrophils, B and T lymphocytes, mast cells) was evaluated in human AAA biopsies. We observed in half of the samples that adventitial tertiary lymphoid organs (ATLOs) with a thickness from 0.5 to 2 mm were located exclusively in the adventitia. Out of the 850 miRNA that were screened by microarray in isolated ATLOs (n = 2), 164 miRNAs were detected in ATLOs. The three miRNAs (miR-15a-3p, miR-30a-5p and miR-489-3p) with the highest expression levels were chosen and their expression quantified by RT-PCR in isolated ATLOs (n = 4), M1 (n = 2) and M2 macrophages (n = 2) and entire aneurysmal biopsies (n = 3). Except for the miR-30a-5p, a similar modulation was found in ATLOs and the two subtypes of macrophages. The modulated miRNAs were then evaluated in the plasma of AAA patients for their potential as AAA biomarkers. Our data emphasize the potential of miR-15a-3p and miR-30a-5p as biomarkers of AAA but also as triggers of ATLO evolution. Further investigations will be required to evaluate their targets in order to better understand AAA pathophysiology.     

Aryl Bis‐Sulfonamide Inhibitors of IspF from Arabidopsis thaliana and Plasmodium falciparum

2‐Methylerythritol 2,4‐cyclodiphosphate synthase (IspF) is an essential enzyme for the biosynthesis of isoprenoid precursors in plants and many human pathogens. The protein is an attractive target for the development of anti‐infectives and herbicides. Using a photometric assay, a screen of 40 000 compounds on IspF from Arabidopsis thaliana afforded symmetrical aryl bis‐sulfonamides that inhibit IspF from A. thaliana (AtIspF) and Plasmodium falciparum (PfIspF) with IC₅₀ values in the micromolar range. The ortho‐bis‐sulfonamide structural motif is essential for inhibitory activity. The best derivatives obtained by parallel synthesis showed IC₅₀ values of 1.4 μm against PfIspF and 240 nm against AtIspF. Substantial herbicidal activity was observed at a dose of 2 kg ha^?1. Molecular modeling studies served as the basis for an in silico search targeted at the discovery of novel, non‐symmetrical sulfonamide IspF inhibitors. The designed compounds were found to exhibit inhibitory activities in the double‐digit micromolar IC₅₀ range.