Liver Steatosis and Steatohepatitis Alter Bile Acid Receptors in Brain and Induce Neuroinflammation: A Contribution of Circulating Bile Acids and Blood-Brain Barrier

A tight relationship between gut-liver diseases and brain functions has recently emerged. Bile acid (BA) receptors, bacterial-derived molecules and the blood-brain barrier (BBB) play key roles in this association. This study was aimed to evaluate how non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) impact the BA receptors Farnesoid X receptor (FXR) and Takeda G-protein coupled receptor 5 (TGR5) expression in the brain and to correlate these effects with circulating BAs composition, BBB integrity and neuroinflammation. A mouse model of NAFLD was set up by a high-fat and sugar diet, and NASH was induced with the supplementation of dextran-sulfate-sodium (DSS) in drinking water. FXR, TGR5 and ionized calcium-binding adaptor molecule 1 (Iba-1) expression in the brain was detected by immunohistochemistry, while Zonula occludens (ZO)-1, Occludin and Plasmalemmal Vesicle Associated Protein-1 (PV-1) were analyzed by immunofluorescence. Biochemical analyses investigated serum BA composition, lipopolysaccharide-binding protein (LBP) and S100β protein (S100β) levels. Results showed a down-regulation of FXR in NASH and an up-regulation of TGR5 and Iba-1 in the cortex and hippocampus in both treated groups as compared to the control group. The BA composition was altered in the serum of both treated groups, and LBP and S100β were significantly augmented in NASH. ZO-1 and Occludin were attenuated in the brain capillary endothelial cells of both treated groups versus the control group. We demonstrated that NAFLD and NASH provoke different grades of brain dysfunction, which are characterized by the altered expression of BA receptors, FXR and TGR5, and activation of microglia. These effects are somewhat promoted by a modification of circulating BAs composition and by an increase in LBP that concur to damage BBB, thus favoring neuroinflammation.     

TRLFS evidence for precipitation of uranyl phosphate on the surface of alumina: environmental implications

We studied the ligand-enhanced sorption of uranyl ions (1-12 μM) on α-alumina colloids suspended in (and pre-equilibrated with) solutions at various concentrations of phosphate ions (P(T) = 0-900 μM). A highly sensitive technique, time resolved laser-induced fluorescence spectroscopy (TRLFS), was used to examine the chemical speciation of uranyl sorbed at trace concentrations (0.4-4 μmol U·g?1). The suspensions with P(T) ≥ 100 μM exhibited high uranyl adsorption, and a very high intensity of fluorescence that increased with the sorbed amounts of phosphate and uranyl. These samples exhibited similar spectral and temporal characteristics of fluorescence emission, evidencing a uniform speciation pattern and a single coordination environment for sorbed U, despite large variation in parameters such as aqueous uranyl speciation, U loading, and extent of coverage of alumina by secondary Al phosphates precipitating on the surface. The results pointed formation of surface precipitates of uranyl phosphates, which are characterized by high quantum yield, peak maxima at positions similar to those of U(VI) phosphate minerals and four lifetimes indicating distortions, in-homogeneities or varying number of water molecules in the lattice. The findings have major implications for our understanding of the mechanisms of immobilization of U at trace levels on surfaces of oxides submitted to phosphated solutions in soils with low pH.     

A method to synthesize SiO2–TiO2 glasses based on the synergy between VAD and ALD techniques: study of TiO2doping profile along radial direction

This study aimed the synthesis of titania–doped silica glasses with controlled TiO₂ concentrations and distribution profiles through the synergy between Vapor-Phase Axial Deposition (VAD) and Atomic Layer Deposition (ALD) techniques. In a first stage, porous boules of pure silica were synthesized by the VAD technique. Afterwards, these boules were submitted to a cyclic doping process with TiCl₄ vapor and H₂O vapor using the principles of ALD technique. Silica–titania on glassy state was obtained after the consolidation of the porous boule at 1400 °C. The effects of VAD and ALD parameters were studied on the radial doping profile homogeneity and glass structure in the consolidated material. Concerning to the radial profile, a more homogeneous glass was obtained for porous boules doped at 90 °C and with higher average density. This temperature was enough to suppress the effect of TiCl₄ condensation on the porous boule surface even for a long TiCl₄ flow time, providing a relatively high doping homogeneity for one and four ALD cycles. The opacity in some consolidated samples was attributed to a segregated phase, which could be completely eliminated by a second heat treatment in flame.     

Frictional Behavior of Polyurethane Modified by Carbon Coatings Synthesized in Dual-Frequency Plasma

A method for changing the surface properties of polymeric materials is by plasma treatment and, in particular, the modification by carbon coatings synthesized using plasma techniques. This article presents the tribological properties of carbon coatings produced on polyurethane substrates by a dual-frequency plasma technique. The analyses were made in terms of placement of the samples in the reactor and the number of modification steps. The samples were characterized by atomic force microscopy and friction tests, which were performed using a ball-on-disc tribometer. The chemical structure of the produced coatings was analyzed with the use of Raman spectroscopy. The obtained results show that the best tribological properties were characteristic of carbon coatings produced on samples placed onto the water-cooled electrode without preliminary ion etching in an argon atmosphere. The modifications decreased the coefficient of friction from 1.2, characteristic of unmodified polyurethane, to a value of about 0.38. The wear rate was reduced from 16.8 × 10^?5 to a value of 4 × 10^?9 mm³/Nm. Based on analysis of the wear tracks it was determined that for the proposed combination of a ZrO₂ ball versus a polyurethane disc modified with a diamond-like carbon (DLC) layer the dominant mechanism of wear is friction; however, in extreme cases, when the DLC coating is worn out, characteristic debris can be observed.