Effect of Sn Content on the Microstructure and Properties of Wire and Arc Additive Manufactured Al-Cu Alloy Deposits.

Al-Cu-Sn alloy deposits with different Sn contents were prepared by the wire and arc additive manufacturing process. The microstructure and mechanical properties of the deposits were examined by metallography, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and tensile tests. The results indicated that the addition of Sn significantly refined the microstructure of the deposits in their as-deposited state, and the grains were transformed from dendrites to equiaxed crystals with a uniform grain size of ∼30 µm. For the deposits with Sn ≥0.15%, the continuous and elongated θ phase on the grain boundary became block-shaped, and the size of the precipitated phase increased. After T6 heat treatment, the θ phase completely dissolved in the substrate in the deposits with Sn ≤0.1%, whereas the θ-phase solid dissolution was incomplete in the deposits with Sn ≥0.15%; the higher the Sn content, the greater the amount of θ phase remaining. After the T6 treatment, the deposits with an Sn content of 0.25% exhibited cracks distributed along the grain boundaries. The addition of Sn significantly increased the density of the θ' phase, which was diffused and uniform in size; with an increase in the Sn content, the distribution density of the θ' phase in the deposits first increased and then decreased as the peak-aging condition was reached. The addition of Sn could effectively improve the mechanical properties of the deposits, which first increased and then decreased with an increase in the Sn content. The mechanical properties of the deposits were optimal at an Sn content of 0.1%, with a tensile strength of 493 MPa, yield strength of 434 MPa, and elongation of 9.5%.

[A multicenter study of the effectiveness of interferon alpha-1b (Hapgen) in treating HBeAg positive chronic hepatitis B patients].

To compare the efficacy and safety of interferon a-1b and interferon a-1b combined with lamivudine in the treatment of HBeAg positive chronic hepatitis B (CHB), to analyze the impact of variable factors on the efficacy, and to investigate the individualized anti-viral regimen for CHB patients. 111 CHB patients were enrolled and randomly divided into two groups. Group A: patients received interferon a-1b (49 patients, 50mug I. M. , qod. ) , Group B: interferon a-1b (idem) combined with lamivudine for 6-12 months or longer(62 patients, 100 mg, P.O. , q.d. ). (1) The HBeAg seroconversion rates of treatment by 12 and 18 months were 28.6% and 36.7% in group A, 29.0% and 38.7% in group B, respectively, no significant difference found between the two groups at the end of treatment (x2=0.003, P value is more than 0.05; x2=1.500, P value is more than 0.05). (2) The HBV DNA undetectable rates of treatment by 6 months, 12 months and 18 months were 8.2%, 53.1% and 57.1% in group A, 66.1%, 83.9% and 88.7% in group B, respectively, still no significant difference existed between the two groups (x2=38.150, P value is less than 0.05; x2=12.073, P value is less than 0.05, x2=14.459, P value is less than 0.05). (3) In group A, the HBeAg seroconversion rates for male and female patients were 34.5% and 40.0% respectively, no significant difference found between. As regard ages the rates were 34.9% and 50.0% for patients younger or more than 40 years of age, no significant difference existed between. The HBeAg seroconversion rate was higher in patients with lower baseline serum HBV DNA loads ( less than 6 log10 copies/ml) . (4) The rates of patients with fever and blood abnormality were 36.7% and 34.7% in group A, 32.3% and 27.4% in group B, respectively. The total incidences of adverse events were similar between group A and B (x2=0.244, P value is more than 0.05; x2=0.682, P value is more than 0.05). (5) The ratio of drug resistance in group B was only 1.6%. The adverse events of interferon a-1b treatment for CHB are low and mild. The HBeAg seroconversion rate persistently raises with the extension of interferon a-1b treatment course. The HBV DNA undetectable rate of interferon a-1b combined with lamivudine is significantly higher than that of interferon a-1b and the drug resistance of lamivudine can be reduced obviously by combination therapy.