Search

International audience; The microstructure and oxidation resistance of Laser Beam Melted (LBM) and Conventionally Manufactured (CM) Inconel 625 alloys were studied at 900 °C and 1050 °C. The microstructure of the LBM samples was cellular, with Nb and Mo segregations located at the cell walls. At 900 °C, the oxidation rate was similar for both materials but was clearly higher for the LBM material at 1050 °C. This high oxidation rate induced poor oxide scalecompactness, void formation in the subsurface region and the formation of a high amount of Nb1.5Cr0.5O4 at the alloy-oxide interface.

International audience

Oxidation of chromium at 800 °C for 30 min at oxygen activity from 5.10−14 atm to 5.10−13 atm have been conducted to grow an insulating chromia. Microstructural and semiconducting properties have been investigated using electron microscopy and photoelectrochemistry. The scales always exhibit a duplex microstructure with equiaxed and columnar grains, as well as a both n-type and insulating semiconduction type. Successive oxidation tests have demonstrated the higher protective nature of this chromia scale compared to the air grown one. Chromia semiconducting properties are finally described vs. oxygen activity in a large range of variation.

BACKGROUND The prognostic relevance of health-related quality of life (HRQoL) has been scarcely studied in the dialysis population and the prognostic power for mortality of the HRQoL domains is unknown. METHODS We tested the prognostic value for mortality of the HRQoL domains included in the 36-item Short Form Health Survey (SF-36) by Cox's regression analysis and by state-of-the-art prognostic techniques {explained variation in mortality [R2], calibration, discrimination [Harrell's C], risk reclassification [Net Reclassification Index (NRI)], Integrated Discrimination Index [IDI]} in a cohort of 951 patients on chronic haemodialysis. RESULTS In multivariable Cox models, all but two domains (role limitation due to physical health and due to emotional problems) were independently related with mortality. Physical functioning was the domain adding the highest explanatory power (R2+5.3%) to a basic model including established risk factors for mortality in the dialysis population. The same domain improved risk calibration and showed the highest Harrell's C (+1.7%) and the highest reclassification power (categorical NRI + 8.7%, continuous NRI +46%, P ≤ 0.006) and the highest IDI (+3.4%, P

The oxidation behaviour of four model alloys with the composition Ni–25Cr–xMn (with x = 0, 0.5, 1 and 1.5 wt%) was investigated at 1050 °C in air by thermogravimetry and by in situ observations in an environmental scanning electron microscope (ESEM). The addition of manganese modifies the oxidation rate of Ni–25Cr alloys by (1) increasing the parabolic constant k p compared to that for Ni–25Cr and (2) lowering the short-time oxidation rate. Regardless of the Mn concentration, in situ ESEM observations indicated the formation of spinel crystallites from the very beginning of the oxidation process. The size of the spinel crystallites was directly linked to the initial Mn concentration. The obtained results suggested that the formation of the spinel layer at the top of the chromia oxide scale rather than at the metal–oxide interface as thermodynamically expected must be attributed to the higher diffusion rate of Mn than Cr both in the lattice and at the grain boundary.

In order to properly study the foundation of a State, a paradigm of thought or any other organization, we should analyze the historical context which produced the conditions for this phenomenon to happen, in all its variables and components. The Jewish question cannot certainly be relegated only to the 20th century, but surely it was the century in which the cultural, political, economic, and social debate was the expression of a collective will to create a Nation and develop and transform it into a key country in the context of global geopolitics.

International audience; Environmental/thermal barrier coatings (E/TBCs) were applied on an Nb/Nb5Si3-based alloy. The substrate material with the nominal composition Nb-23Ti-4Hf-3Cr-6Al-20Si (at.%) was manufactured by plasma melting. Rectangular platelets of this alloy were coated with chromia-silica forming M7Si6-based (M = Ti, Nb, Cr, X with X = Ni, Co, Fe) bond coats produced by pack cementation. The Co- and Fe-modified M7Si6-based layers also contained boron. On these grit blasted bond coats, ceramic topcoats of 7 wt.% yttria partially stabilised zirconia (YSZ) and gadolinium zirconate (GZO) were deposited using electron-beam physical vapour deposition. The E/TBC systems were thermally cycled at 1100 °C and 1200 °C in laboratory air (1 h at high temperature, 10 min at ambient temperature). Cross-sectional examinations of the samples after cyclic testing were carried out using scanning electron microscopy to study the protection capability of the E/TBC systems and failure mechanisms.The lifetimes of the E/TBC systems exceeded the maximum exposure period of 1000 cycles at 1100 °C. When cyclically tested at 1200 °C, the samples with Ni-modified and boron containing Co-modified M7Si6-based bond coats failed within 700 cycles. Failure was caused by spallation of thick oxides scales thermally grown on the substrate after degradation of the bond coats. The E/TBC systems with boron containing Fe-modified M7Si6-based bond coats exhibited lifetimes approaching 1000 cycles at 1200 °C. For both YSZ and GZO topcoats, chemical reactions with the TGOs were observed.

In this paper we investigate a one-dimensional p -Laplacian problem, whose nonlinearity comprises both p -sublinear and p -superlinear terms. By studying the multiplicity of solutions to an auxiliary problem, we show how convenient choices of the parameters involved yield the existence of at least three classical positive solutions satisfying Hopf's boundary condition. In addition, we provide the existence of two distinct curves of parameters along which our problem admits at least a compacton-type solution.

The PbO–Al2O3 system has been extensively studied in literature. In the present study, experimental work was conducted in which equilibria between phases were investigated under air between 600°C and 800°C by X-ray diffraction. Three intermediate compounds reported in literature were confirmed, which are PbAl12O19 (1PbO:6Al2O3), PbAl2O4 (1:1) and Pb2Al2O5 (2:1). Results support a widely accepted version of the phase diagram in which these compounds exist. On the basis of the results obtained in this study and data considered from literature, a thermodynamic modeling according to the Calphad approach was performed, where all intermediate phases were considered as stoichiometric compounds and where the liquid phase was described by a two-sublattice ionic liquid model. Good agreement has been obtained from thermodynamic optimization in comparison with experimental results.

The review briefly summaries main features of extracellular vesicles, a joint terminology for exosomes, microvesicles, and apoptotic vesicles. These vesicles are in the center of interest in biology and medical sciences, and form a very active field of research. Mass spectrometry (MS), with its specificity and sensitivity, has the potential to identify and characterize molecular composition of these vesicles; but as yet there are only a limited, but fast-growing, number of publications that use MS workflows in this field. MS is the major tool to assess protein composition of extracellular vesicles: qualitative and quantitative proteomics approaches are both reviewed. Beside proteins, lipid and metabolite composition of vesicles might also be best assessed by MS techniques; however there are few applications as yet in this respect. The role of alternative analytical approaches, like gel-based proteomics and antibody-based immunoassays, are also mentioned. The objective of the review is to give an overview of this fast-growing field to help orient MS-based research on extracellular vesicles. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 35: 3–21, 2016.

The onset of Alzheimer disease (AD) is influenced by several risk factors comprising diabetes. Within this context, antidiabetic drugs, including metformin, are investigated for their effect on AD. We report that in the C57B6/J mice, metformin is delivered to the brain where activates AMP-activated kinase (AMPK), its molecular target. This drug affects the levels of β- secretase (BACE1) and β-amyloid precursor protein (APP), promoting processing and aggregation of β-amyloid (Aβ), mainly in the cortex region. Moreover, metformin induces mitochondrial dysfunction and cell death by affecting the level and conformation of Translocase of the Outer Membrane 40 (TOM40), voltage-dependent anion-selective channels 1 (VDAC1) and hexokinase I (HKI), proteins involved in mitochondrial transport of molecules, including Aβ. By using biophysical techniques we found that metformin is able to directly interact with Aβ influencing its aggregation kinetics and features. These findings indicate that metformin induces different adverse effects, leading to an overall increase of the risk of AD onset.

""Myoglobin is an alpha-helical globular protein containing two highly conserved tryptophanyl residues at positions 7 and 14 in the N-terminal region. The simultaneous substitution of the two residues increases the susceptibility of the polypeptide chain to misfold, causing amyloid aggregation under physiological condition, i.e., neutral pH and room temperature. The role played by tryptophanyl residues in driving the folding process has been investigated by examining three mutated apomyoglobins, i.e., W7F, W14F, and the amyloid-forming mutant W7FW14F, by an integrated approach based on far-ultraviolet (UV) circular dichroism (CD) analysis, fluorescence spectroscopy, and complementary proteolysis. Particular attention has been devoted to examine the conformational and dynamic properties of the equilibrium intermediate formed at pH 4.0, since it represents the early organized structure from which the native fold originates. The results show that the W -> F substitutions at position 7 and 14 differently affect the structural organization of the AGH subdomain of apomyoglobin. The combined effect of the two substitutions in the double mutant impairs the formation of native-like contacts and favors interchain interactions, leading to protein aggregation and amyloid formation.""

Background. Depending on both membrane composition and solute transport rate across the membrane, protein composition of the dialysate of patients receiving peritoneal dialysis (PD) has recently become of great interest. Unfortunately, thus far few studies have focused on dialysate characterization, and further investigations are required to better understand the biological mechanisms influencing PD efficiency.Methods. Different classical proteomic approaches were combined with advanced mass spectrometric (MS) techniques to analyse peritoneal fluid (PF) protein composition of adult patients receiving PD. Characterization was performed by using 1D gel electrophoresis combined with nano-RPHPLCESIMS/MS and shotgun proteomics, while comparative analyses were performed coupling 2D gel electrophoresis with MALDI-TOF MS.Results. The study allowed the identification of 151 different proteins from PF, which are mainly of plasmatic origin. Comparison of PD effluents characterized by different glucose concentrations demonstrated four proteins (apolipoprotein A-IV, fibrinogen beta chain, transthyretin and alpha-1-antitrypsin) to be under-expressed in the highest osmolar solution having 4.25% compared to others having 1.5% and 2.5% glucose. All of them were found to be involved in the inflammatory processes.Conclusions. This study provides a possible platform for future diagnostic and therapeutic applications in the field of PD and allowed the identification of potential targets to be used in preventing inflammatory processes induced by the exposure to dialysis solutions. © 2009 The Author.

Renal cell carcinoma (RCC) is a frequent adult malignancy comprising different subtypes, with clear cell renal cell carcinoma (CCRCC) the most common. CCRCC is associated with the loss of function of the von Hippel-Lindau (VHL) gene. pVHL, the product of the VHL gene, is a component of an E3 ubiquitin ligase complex which targets proteins for degradation. In the absence of functional pVHL, a series of proteins accumulate in the cells, including hypoxic-inducible factor-1a (HIF-1a) and the products of the target genes of pVHL, such as vascular endothelial growth factor (VEGF). The activation of this pathway explains the use of both VEGF and VEGF-receptor inhibitors (bevacizumab, sunitinib and sorafenib) in the therapy of advanced CCRCC. In addition, mammalian target of rapamycin (mTOR), an intracellular serine/threonine kinase, is also implicated in HIF-1a regulation, thus reinforcing the rationale for using mTOR inhibitors (rapamycin) in CCRCC. Proteomic technologies have been applied to human renal cancer to detect biomarkers able to guide physicians for diagnostic and prognostic purposes. Among others, vimentin, heat shock protein 27 (Hsp27), annexin IV and serum amyloid alpha-1 (SAA-1) have been identified as reliable markers of RCC that are potentially useful in the clinical setting. Renal cell carcinoma (RCC) is a frequent adult malignancy comprising different subtypes, with clear cell renal cell carcinoma (CCRCC) the most common. CCRCC is associated with the loss of function of the von Hippel-Lindau (VHL) gene. pVHL, the product of the VHL gene, is a component of an E3 ubiquitin ligase complex which targets proteins for degradation. In the absence of functional pVHL, a series of proteins accumulate in the cells, including hypoxic-inducible factor-1α (HIF-1α) and the products of the target genes of pVHL, such as vascular endothelial growth factor (VEGF). The activation of this pathway explains the use of both VEGF and VEGF-receptor inhibitors (bevacizumab, sunitinib and sorafenib) in the therapy of advanced CCRCC. In addition, mammalian target of rapamycin (mTOR), an intracellular serine/threonine kinase, is also implicated in HIF-1α regulation, thus reinforcing the rationale for using mTOR inhibitors (rapamycin) in CCRCC. Proteomic technologies have been applied to human renal cancer to detect biomarkers able to guide physicians for diagnostic and prognostic purposes. Among others, vimentin, heat shock protein 27 (Hsp27), annexin IV and serum amyloid alpha-1 (SAA-1) have been identified as reliable markers of RCC that are potentially useful in the clinical setting. © 2011 Società Italiana di Nefrologia.

The semiconducting properties of chromia, studied by photoelectrochemistry (PEC), are varied by oxidizing pure Cr as a function of temperature and oxygen activity. At 800 °C and a p(O2) of 10-14 atm, a single n-chromia is observed, while at 900 °C and a p(O2) of 10-12 atm a n- & p-layer is obtained. For intermediate conditions, an insulating stoichiometric Cr2O3 is identified at 850 °C for a p(O2) of 10-13 atm. The TEM investigation reveals a duplex morphology for every scales: an equiaxed (resp. columnar) morphology has been developed in the internal (resp. external) part. Between these two subscales, a textured chromia layer has been identified as the first layer to form. Finally, the association of TEM and PEC techniques permits the identification of major point defects. It is revealed that the morphology is only linked to the growth direction: anionic (resp. cationic) growth leads to equiaxed (resp. columnar) grains.

International audience; The high-temperature oxidation behavior of a binary Ni-30Cr model alloy has been studied at 1050 °C at three oxygen partial pressures p(O2): ~10−14, ~10−10, and ~10−5 atm. The oxide scales were characterized using grazing X-Ray diffraction, Raman spectroscopy, EDX spectroscopy, and TEM microscopy. The semiconducting properties of the oxide scale have been investigated using photoelectrochemistry (PEC). Classical characterizations show that chromia is the main oxidation product whatever maybe the oxygen activity. PEC reveals additionally the presence of (i) n-type Cr2O3 at p(O2) ~ 10−14 atm and (ii) both n-type and p-type Cr2O3 at higher oxygen pressures. The mechanisms of oxidation are discussed as a function of the major point defects that govern the oxide scale growth.

International audience; Improvement of the calcium-magnesium aluminosilicate (CMAS) infiltration mitigation concept in thermal barrier coatings (TBC) requires fundamental data on thermochemical reaction involving rare-earth oxide candidate as ZrO2 alloying element. This study investigates, through a model approach, Gd2O3 dissolution at 1200 °C in a synthetic model CAS melt (64.4SiO2–9.3Al2O3–26.4CaO mol. %) and the stability of the precipitated Gd-apatite Ca2Gd8(SiO4)6O2 and Ca3Gd2(Si3O9)2 cyclosilicate phases. The two Gd-rich silicates have been synthesized by solid-state reaction and then characterized by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). The interactions of Gd2O3, Gd-apatite and Gd-cyclosilicate with CAS have been observed by scanning electron microscope (SEM) after various times of contact at 1200 ̊C, giving information about dissolution/precipitation processes. Dissolution kinetics has been evaluated by electron probe microanalysis (EPMA) measurements in the CAS melt. A discussion is finally provided concerning the thermodynamic stability of all phases of the system and confronted with kinetics considerations.

In this paper we examine the existence of multiple solutions of parametric fractional equations involving the square root of the Laplacian $A_{1/2}$ in a smooth bounded domain $\Omega\subset \mathbb{R}^n$ ($n\geq 2$) and with Dirichlet zero-boundary conditions, i.e. \begin{equation*} \left\{ \begin{array}{ll} A_{1/2}u=\lambda f(u) & \mbox{ in } \Omega\\ u=0 & \mbox{ on } \partial\Omega. \end{array}\right. \end{equation*} The existence of at least three $L^{\infty}$-bounded weak solutions is established for certain values of the parameter $\lambda$ requiring that the nonlinear term $f$ is continuous and with a suitable growth. Our approach is based on variational arguments and a variant of Caffarelli-Silvestre's extension method.