Atherosclerosis as a chronic inflammatory disease resulting from the imbalance of the pro- and anti-inflammatory factors in the vessel wall. PAF and PAF-like oxidized phospholipids generated upon LDL oxidation in the intima of the arteries may interact with infiltrated monocytes/macrophages and lead to the alteration of gene expression patterns accompanied by an impaired production of chemokines, interleukins and proteolytic and lipolytic enzymes. The aim of this study was to evaluate the binding capacity of the major component of PAF-like oxidized phospholipids, namely the 1-palmitoyl-2-oxovaleroyl-sn-glycero-3-phosphorylcholine (POVPC) to PAF-receptor (PAF-R) on the surface of human monocytes/macrophages and to further characterize the gene expression induced by such binding. We show that, POVPC binds to cultured human macrophages via PAF-R and transduces the signals leading to the intracellular Ca2+ fluxes and modifies the transcription levels of numerous pro-inflammatory and pro-atherogenic genes. Although a some similarity of the gene expression patterns was observed when macrophages were activated with POVPC versus PAF, we observed that only POVPC treatment induced a several-fold activation of IL-8 gene. In turn, only PAF activated PAF-R, matrix metalloproteinase-13 and 15-lipoxygenase mRNA accumulation. Thus, we suggest, that POVPC signals in mature macrophages only in part through the PAF-R, a part of its effects may involve other receptors.

The deformation behaviour and fracture of an open-cell nickel foam were analysed using X-ray microtomography at the ESRF, Grenoble, France. In situ tensile and compression tests were performed at a resolution of 2 and 10 mm. The initial morphology of the foam was studied using 3D image analysis. Parameters such as the cell volume and strut length distributions, number of faces per cell, number of nodes per face and the shape of the most representative cells were determined. The cells are shown to be non-spherical due to the initial geometrical anisotropy of the polyurethane foam template and to the load applied to the nickel foam during processing. This geometrical anisotropy is shown to be related to the observed anisotropy of the elastic properties of the material using a simple beam model. In tension, bending, stretching and alignment of struts are observed. A tensile test in the longitudinal direction is shown to reinforce the privileged orientations of the cells. In contrast, a tensile test in the transverse direction leads to a more isotropic distribution of the cells. These features are illustrated by pole figures of the three axes of equivalent ellipsoids for all cells at different strain levels. Compression tests are associated with strain localization phenomena due to the buckling of struts in a weaker region of the foam. Finally, study of open-cell nickel foam fracture shows that cracks initiate at nodes during tensile tests and that the damaged zone is about five cells wide. Free edge effects on crack initiation are also evidenced.

The mechanical properties of open-cell nickel foams are investigated for the range of densities used in industrial applications for energy storage. The obtained Young’s modulus, compression yield stress and tensile fracture stress are compared to the predictions of models based on periodic, Penrose and Voronoi beam networks. It is found that Gibson and Ashby’s model [L.J. Gibson, M.F. Ashby, Cellular Solids, Cambridge University Press, Cambridge, 1998] provides the proper scaling laws with respect to relative density for almost all investigated properties. The strong anisotropy of the observed overall responses can also be accounted for. The two-dimensional strain field during the tension of a nickel foam strip has been measured using a photomechanical technique. Non-homogeneous deformation patterns are shown to arise. The same technique is used to obtain the strain field around a circular hole in a nickel foam strip. The observed deformation fields are compared to the results of a finite element analysis using anisotropic compressible continuum plasticity.

Male mice (CD-1 type) were fed for 14 days diets containing 4 grams of ethyl esters of linoleic acid (LA) per 100 g of diet supplemented with 0, 0.4, 0.8 or 4 g of ethyl ester of docosahexaenoic acid (DHA). The total fat content of the diets was adjusted to 10% by weight by adding a 1:1 mixture of tristearin and triolein. Kidney microsomes from these mice were prepared and analysed for fatty acid content and Na + –K + ATPase activity. Feeding the lowest amount of DHA, representing a 1:10 dietary DHA/LA ratio, resulted in an increase in DHA content from 6.5 to 17 mole % of phospholipids from microsomes compared to diets without DHA. Higher dietary DHA levels did not result in further increases in tissue DHA levels. DHA feeding also caused a slight increase in phospholipid eicosapentaenoic acid (EPA). The increase in the tissue DHA and EPA levels was accompanied by a decrease in arachidonic acid levels. Dietary DHA resulted in a decrease in the specific activity of kidney microsomal Na + –K + ATPase from 508±70 to 261±25 ug PO 4 − min −1 mg protein −1 in mice consuming 4 g DHA per 100 g diet

Mice were fed diets containing a constant supply of linoleic acid (18:2n-6, LA) as ethyl ester representing 5% by weight of the total fat (5 wt%), in combination with graded amounts of purified docosahexaenoate (22:6n-3, DHA). Cardiac sarcoplasmic reticulum (SR) and mitochondrial phospholipids (PL) from mice fed the diet without DHA contained higher levels of n-6 long chain polyunsaturated fatty acids (PUFA) (22:4n-6 and 22:5n-6) compared to total PL of liver. In the cardiac mitochondrial PL, the level of LA, DHA, the total content of PUFA and the P/S ratio were significantly higher than in SR. A small increase in dietary DHA from 0 to 0.43 wt% induced a 3.6-fold increase in PL DHA content from both cardiac organelles, with a concurrent reduction of n-6 PUFA. The changes in fatty acid PL composition were much more moderate when dietary DHA level was increased to 0.85 and 3.74 wt%. Feeding the lowest amount of DHA resulted in a 6-fold decrease in the value of n-6/n-3 PUFA ratio and a 3.5-fold decrease in the value of 20 carbon chain/22 carbon chain PUFA ratio. DHA was readily depleted from cardiac PL, and only arachidonic acid was retained in the PL from both organelles, after feeding a fat-deficient diet. Despite these drastic modifications in PL fatty acid composition, the maximum velocity (Vm) of SR Ca2+, Mg2+-ATPase was not affected, which indicates that SR cardiac membrane adapts to changes in fatty acid composition to prevent important modifications of its functional properties. However, the Vm of mitochondrial oligomycin-sensitive ATPase was slightly increased in mice fed the lowest amount of DHA. This might be due to an increase in P/S ratio and/or to a modification of cardiolipin fatty acid composition, since this PL is required for optimum function of this enzyme. It is concluded that DHA is strongly taken up by mouse cardiac PL, even in the presence of high dietary LA levels, but its acylation into PL has only little effect on the cardiac ATPase activities.

The effects of dietary n−3 and n−6 polyunsaturated fatty acids on the fatty acid composition of phospholipid, Ca ++ · Mg ++ ATPase and Ca ++ transport activities of mouse sarcoplasmic reticulum were investigated. Mice were fed a 2 weight percent fat diet containing either 0.5 weight percent ethyl esters of 18∶3n−3, 20∶5n−3 or 22∶6n−3 as a source of n−3 polyusaturated fatty acid or 0.5 weight percent safflower oil as a cource of n−6 polyunsaturated fatty acid for 10 days. Olive oil (2 weight percent) was used as a control diet. Although feeding n−6 polyunsaturated fatty acid induced very little modifications of the phospholipid sarcoplasmic reticulum fatty acid composition, feeding n−3 polyunsaturated fatty acid altered it markedly. Inclusion of 18∶−3, 20∶5n−3 or 22∶6n−3 in the diet caused an accumulation of 22∶6n−3, which replaced 20∶4n−6 and 18∶2n−6 in phospholipid sarcoplasmic reticulum. The saturated fatty acids were significantly increased with a concurrent reduction of 18∶1n−9. These changes in the fatty acid composition resulted in a decrease in the values of the n−6/n−3 polyunsaturated fatty acid ratio and a decrease in the ratio of 20 carbon to 22 carbon fatty acids esterified in the phospholipid sarcoplasmic reticulum. This was associated with a decrease in Ca ++ uptake by n−3 polyunsaturated fatty acid enriched sarcoplasmic reticulum vesicles as compared with n−6 fatty acid and control diet sarcoplasmic reticulum vesicles. However, neither the affinity for Ca ++ nor the maximal velocity of ATP hydrolysis activity of Ca ++ ·MG ++ ATPase were altered by the different diets. The data suggest that the incorporation of 22∶6n−3 and/or the decrease of 20∶4n−6 plus 18∶2n−6 in the phospholipid sarcoplasmic reticulum may affect the membrane lipid bilayer structure and make it more permeable to Ca ++ .

The present understanding of the properties of heteroepitaxial Si films grown on yttria stabilized zirconia single crystals (YSZ) is reviewed with particular emphasis on the properties of Si films resulting from high temperature post oxidation treatment. The crystalline, physic() chemical and electrical properties of Si films obtained by pyrolysis of SiH4 have been characterized by various analytical techniques. The results indicate that under carefully controlled deposition conditions, the crystalline quality (density of defects, of grain boundaries ....) is better for Si deposited on YSZ (SOZ structure), than for Si deposited on sapphire (SOS structure). The Si films, as deposited on YSZ, are highly resistive (cil -,_, 105 Q cm) ; a high temperature annealing in neutral atmosphere improves the quality of the films. In contrast to SOS, self doping is absent in SOZ structures (p lir O. cm). Further

Principes generaux et aspects theoriques de la reduction de couches d'oxyde au travers d'une membrane d'electrolyte solide. Conditions thermodynamiques et cinetiques de la reduction

(100) heteroepitaxial Silicon films with thicknesses in the 0.4-1 μm range have been deposited onto single-crystal substrates of yttria-stabilized zirconia (YSZ) by pyrolysis of SiH4 at ≈ 980° C. Using the well-known oxygen transport properties of YSZ, we have subsequently been able to grow a buried thermal SiO2 layer at the Si-YSZ interface, resulting in a Si(100)/amorphous SiO2/YSZ(100) structure, in which the most defective part of the initial epitaxial film has been eliminated. The interface SiO2 layers have been characterized by Rutherford backscattering spectroscopy and scanning electron microscopy. The oxygen transport mechanism through the YSZ substrate is also briefly discussed.

GaAs and GaP single crystalline samples were implanted/sputtered with N, O, Ar and Te ions to doses >1017 cm−2 at energies corresponding to several hundred ångströms of projected range. Depth distributions of the implanted atoms along with those of both constituents of the substrate were measured by the combined low-and-high-energy backscattering techniques. Residual damage within and beneath the irradiated region was examined by the use of photoluminescence spectroscopy. For GaAs a strong depletion of the group V component observed in the surface region after high-dose oxygen implantation and relatively small changes in stoichiometry under argon or tellurium bombardment suggest a mechanism in which a cascade-driven chemical interaction between the colliding atoms is responsible for preferential sputtering. In addition, analysis of the luminescence spectra indicates that the distribution of corresponding vacancies extends to depths well below the range of implanted ions. For GaP, no evidence of substantial stoichiometry modifications was found; this behaviour, very different to that of GaAs, may be attributed to the absence of highly volatile GaP-based oxygenated species.

The purpose of this work is twofold: (i) to study the damage induced by ion implantation, with special attention to low implanted doses; (ii) to study the efficiency of annealing techniques — particularly incoherent light annealing — in order to relate the electrical activity of implanted atoms to damage annealing.

Na β/β" alumina-like thin films on sapphire substrates were prepared by R.F. sputtering deposition of an amorphous Al2O3 layer, Mg ion implantation and subsequent thermal treatment (1270°C during 72 hours) in Na-rich environment. Thin films were converted into protonic isomorph by deuterium plasma treatment at 400°C. Structural characterization (Raman, I.R.), composition nuclear microanalysis and electrical properties are discussed.

We have studied the effects of pulsed laser irradiation on silicon implanted, thermally activated, Calcia Stabilized Zirconia (CSZ) capped GaAs substrates. Reference substrates have also been irradiated in air for comparison. CSZ as a solid electrolyte has been used to chemically reduce the GaAs surface native oxides prior to irradiation while maintaining the surface stoechiometry. Our results indicate a spectacular decrease in defect density after laser irradiation of the CSZ capped-native oxide free samples, as compared to the samples irradiated in air.

CaO stabilized zirconia (CSZ) is a well known oxygen conductor. Thin films of such material (1000 Å thick) have been obtained by Ca implantation in zirconia film followed by short annealing in air at moderate temperature. Studies of chemical composition and of Ca depth profile as a function of implantation dose and annealing temperature have been carried out using RBS and nuclear reactions. Measurements of dc conductivity and of ionic transport number have shown that initial electronic conductivity, associated to the defects introduced by ion implantation, has vanished after annealing at T ≈ 200–300°C and that ionic conductivity appears at temperatures ⩾ ∼ 400°C. The implanted layers exhibit higher ionic conductivity than bulk ceramics of the same compositions.

The interface between GaAs and its native oxide is thermodynamically unstable and introduces many defects, which are mainly responsible for the poor electrical properties of this material. We propose in this paper an original way of reducing the native oxide layer and then obtaining a thermodynamically stable and abrupt interface between GaAs and a deposited dielectric. It is shown that these conditions are well fulfilled by layers of calcia-stabilized zirconia (CSZ), which is well known as a solid electrolyte. CSZ is a good insulator at moderate temperatures and allows the reduction of the native oxide at high temperatures. Thermodynamic analysis of the GaAs oxide and of the CSZ solid solution show that, in an H2 atmosphere containing 20 ppm of water, the GaAs oxide is reduced at an annealing temperature T⩾500 °C, whereas the CSZ solid solution is stable up to T=2200 °C. Our aim in this paper was to study the mechanisms of native oxide reduction at 550 °C⩽T⩽800 °C through a thin layer of CSZ. Nuclear microanalysis, Rutherford backscattering in random and channelling geometry and ion scattering spectrometry were used to measure the oxygen losses during the annealing treatment and to study the gallium and arsenic epitaxial regrowth. It was found that the native oxide reduction takes place even in the case of intentional preformation of a relatively thick (approximately 250 Å) GaAs anodic oxide layer. The gallium and arsenic atoms liberated by oxide reduction are epitaxially regrown on the underlying substrate and a good and relatively abrupt interface is observed between the GaAs and the CSZ deposited layers. Preliminary electrical measurements seem to indicate that an inversion layer can be obtained, although hysteresis and frequency dispersion do occur in the capacitance-voltage curves, as commonly observed.