About the Al\u2013Cu\u2013Si isothermal section at 500\ub0C and the stability of the epsilon-Cu15Si4 phase

a b s t r a c t The 500 C isothermal section of the Al\u2013Cu\u2013Si system has been determined in the whole composition range, with special attention to the Cu-rich corner. A number of Cu\u2013Si binary alloys equilibrated at 500\u2013 780 C have also been investigated. A ternary point compound at 1.5 at% Al and 21 at% Si has been identified. It has the same crystal structure of the binary phase previously reported as epsilon-Cu15Si4. This phase however is not stable in the binary system, at least between 500 and 780 C, and it is stabilised by small amounts of impurities. The gamma1- (Al,Cu) phase dissolves about 11.5 at% Si and ternary solubility extends in the direction of a constant valence electron concentration. The binary k-(Cu,Si) phase is stable in a ternary solubility range close to the (Cu) terminal solid solution

The 500\ua0\ub0C Isothermal Section of the Al-Co-Nd Ternary System

The Al-Co-Nd isothermal section at 500 C has been investigated in the whole composition range by means of x-ray diffraction, optical and scanning electron microscopy and electron probe microanalysis. The following ternary phases have been identified or confirmed: s1-Nd4 CoAl (cF96-Gd4RhIn), s2-NdCo2Al8 (oP44-CeFe2Al8), s3-NdCo3Al11 (unknown), s4-Nd2Co3Al9 (oS56-2Co3Ga9) s5-Nd5Co2Al2 (unknown), s6-Nd2Co6Al19 (mS108 U2Co6Al19), s7-Nd7Co6Al7 (tP40-Pr7Co6Al7), s8-Nd2Co 2Al(oI10-W2CoB2), s9-Nd13Co14-xAl4?x (0 B x B 0.7, oS28-W3CoB3). The complex system of phase equilibria linking the large number of binary and ternary Al-Co-Nd phases at 500 C has been completely determined. The general characteristics of the section have been discussed in comparison with those of other Al-Co-R systems

Experimental investigation of the Cu\u2013Si phase diagram at x(Cu)>0.72

Cu-Si phase equilibria have been investigated at compositions greater than 72 at.% Cu by X-ray diffraction, optical and electronic microscopy, electron probe microanalysis and differential thermal analysis. The general aspects of the phase equilibria already reported in literature have been substantially confirmed, but selected composition ranges and the nature of a few invariant equilibria have been modified. In particular stability ranges of the beta, delta and eta phases have been slightly modified as well as temperature and nature of the invariant equilibria related to the g % d transformation. Stability of the epsilon-(Cu15Si4) phase has been especially investigated concluding that it is thermodynamically stable but kinetically inhibited by nucleation difficulties which become especially effective when samples are synthesized in very high purity conditions. Crystal structure and composition ranges of the high temperature beta and delta phases, despite difficulties by the non-quenchability of these phases, have been investigated by different methods including high temperature XRD

Relationship Between Anti-DFS70 Autoantibodies and Oxidative Stress

Background: The anti-DFS70 autoantibodies are one of the most commonly and widely described agent of unknown clinical significance, frequently detected in healthy individuals. It is not known whether the DFS70 autoantibodies are protective or pathogenic. One of the factors suspected of inducing the formation of anti-DFS70 antibodies is increased oxidative stress. We evaluated the coexistence of anti-DFS70 antibodies with selected markers of oxidative stress and investigated whether these antibodies could be considered as indirect markers of oxidative stress. Methods: The intensity of oxidative stress was measured in all samples via indices of free-radical damage to lipids and proteins such as total oxidant status (TOS), concentrations of lipid hydroperoxides (LPH), lipofuscin (LPS), and malondialdehyde (MDA). The parameters of the non-enzymatic antioxidant system, such as total antioxidant status (TAS) and uric acid concentration (UA), were also measured, as well as the activity of superoxide dismutase (SOD). Based on TOS and TAS values, the oxidative stress index (OSI) was calculated. All samples were also tested with indirect immunofluorescence assay (IFA) and 357 samples were selected for direct monospecific anti DFS70 enzyme-linked immunosorbent assay (ELISA) testing. Results:: The anti-DFS70 antibodies were confirmed by ELISA test in 21.29% of samples. Compared with anti-DFS70 negative samples we observed 23% lower concentration of LPH (P = .038) and 11% lower concentration of UA (P = .005). TOS was 20% lower (P = .014). The activity of SOD was up to 5% higher (P = .037). The Pearson correlation showed weak negative correlation for LPH, UA, and TOS and a weak positive correlation for SOD activity. Conclusion: In samples positive for the anti-DFS70 antibody a decreased level of oxidative stress was observed, especially in the case of samples with a high antibody titer. Anti-DFS70 antibodies can be considered as an indirect marker of reduced oxidative stress or a marker indicating the recent intensification of antioxidant processes