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[en] To investigate the possible role of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNT-alpha) on the pathogenesis of Graves' ophthalmopathy (GO), the serum IL-6 and TNF-alpha concentrations were evaluated by radioimmunoassay from 38 patients with GO, 33 patients with Graves' disease (GD) without ophthalmopathy, and also from 24 healthy subjects. The serum IL-6, TNF-alpha levels were significantly higher in the patients with GO(x-bar +- s 341.7 +- 151.8 and 784.4 +- 1103.5 pg/mL) than those in the patients with GD(x-bar +- s 174.7+-53.5 and 597.9 +- 400.0 pg/mL), (P<0.01, P<0.05). No significant difference in the mean serum IL-6, TNF-alpha was found between the patients with GD and normal control group (P>0.05). The serum levels of IL-6 and TNF-alpha in the patients with GO were positively correlated (r = 0.45, P<0.01). The results suggested that IL-6 and TNF-alpha might be an important factor in the pathogenesis of GO
[en] Phase transitions of the Cu60Zr30Ti10 and Cu60Zr20Hf10Ti10 alloys are studied using an in situ X-ray diffraction with synchrotron radiation under different pressures. The products of Cu-based alloys quenched from the melts under high pressure are analyzed and compared with the same alloys casted under ambient pressure. The crystallization and melting processes of Cu60Zr20Hf10Ti10 BMG are also changed under high pressure. The effects of high pressure on crystallization and melting processes of the BMG are discussed.
[en] Research highlights: → The Ni-3 Co-free alloy coating prepared by laser welding. → Ni-3 alloy has excellent combination with stainless steel base. → Ni-3 alloy containing those strengthening phases could have excellent wear resistance and anti-oxidation ability at high temperature. - Abstract: To meet the demand of cobalt-free for the cladding coating materials used on sealing surface of nuclear power valves, a new Co-free, Ni-Cr based alloy powder (Ni-3) has been developed. It has been successfully coated on the surface of stainless steel as the strengthening layer. The XRD result reveals that the primary phase of cladding coating is Ni-based solid solution, and the carbides M7C3 and M23C6 as well as several A3B types of γ' strengthening phases. It indicates that the alloy possesses the high wear resistance, good corrosion resistance and high temperature tolerance. The test results suggest that the micro-hardness of Ni-3 corresponds to that of alloy Stellite 6 which containing cobalt and currently used as material for nuclear power valves. Hence, the developed Ni-3 alloy powder can be the hopeful candidate material for Co-free cladding material used on the surface of nuclear power valves; it can reduce the nuclear pollution and save the expensive metals.
[en] The electrical properties of ZnO varistors and novel SnO2 varistors have been attributed to their grain boundary barriers. In this report, the techniques of capacitance-voltage (C-V) measurement and deep level transient spectroscopy (DLTS) were employed to investigate the effect of different dopants on the electronic states of ZnO-based and SnO2-based varistors. Two trap levels were determined in typical ZnO varistors: trap L1 at Ec-0.15±0.01eV and trap L2 at Ec-0.25±0.01eV. The different dopants affected the parameters of those traps significantly. Two deeper trap levels, trap S1 at Ec-0.30±0.03eV and trap S2 at Ec-0.69±0.03eV, were identified in both SnO2-CoO-Nb2O5 and SnO2-CoO-Nb2O5-Cr2O3 varistors. The variations in the donor density and trap density appear to be associated with the addition of trivalent Cr3+. The features of these trap levels and the defect theory related to the SnO2 varistors need to be further studied.
[en] Highlights: ► A novel Co-free alloy FeCr-1 for sealing surface of nuclear power valves has been developed. ► FeCr-1 alloy coating has been prepared with laser cladding by a new system of powder feeding inside hollow laser beam. ► The main mechanical properties of the coating are close to cobalt-based alloy Stellite6. - Abstract: To avoid the activated radiation of cobalt-based alloy, a new cobalt-free Fe-based alloy powder (FeCr-1) has been developed. In addition to the main constituent of Fe, this powder contains C, Ni, Cr, B, Si, W, V, Mo, Mn, etc. By using a hollow laser, FeCr-1 has been successfully prepared on the surface of stainless steel as the cobalt-free strengthening layer. Investigation reveals that the microhardness of this laser cladding coating corresponds to that of cobalt-based alloy Stellite 6. The XRD result reveals that the primary phases of, Fe2SiV, Ni2Si and Si2.2Mn6 as well as various fine carbides such as Fe0.4Mn3.6C, Fe3C and Fe5C2 exist in the coating. Analysis indicates that this kind of alloy has some advantages of high wear resistance, good corrosion resistance and high temperature tolerance. The capability of the Co-free FeCr-1 alloy powder is close to that of Stellite 6, thus it could be the promising candidate material of bead welding used for the new generation nuclear power valves.
[en] Experiments of autogenous laser full penetration welding between dissimilar cast Ni-based superalloy K418 and alloy steel 42CrMo flat plates with 3.5 mm thickness were conducted using a 3 kW continuous wave (CW) Nd:YAG laser. The influences of laser welding velocity, flow rate of side-blow shielding gas, defocusing distance were investigated. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness and tensile strength testing. Results show that high quality full penetration laser-welded joint can be obtained by optimizing the welding velocity, flow rate of shielding gas and defocusing distance. The laser-welded seam have non-equilibrium solidified microstructures consisting of γ-FeCr0.29Ni0.16C0.06 austenite solid solution dendrites as the dominant and very small amount of super-fine dispersed Ni3Al γ' phase and Laves particles as well as MC needle-like carbides distributed in the interdendritic regions. Although the microhardness of the laser-welded seam was lower than that of the base metal, the strength of the joint was equal to that of the base metal and the fracture mechanism showed fine ductility