Improvement in Grain Size Distribution Uniformity for Nuclear-Grade Austenitic Stainless Steel through Thermomechanical Treatment.

In this work, thermomechanical treatment (single-pass rolling at 800 °C and solution treatment) was applied to nuclear-grade hot-rolled austenitic stainless steel to eliminate the mixed grain induced by the uneven hot-rolled microstructure. By employing high-temperature laser scanning confocal microscopy, microstructure evolution during solution treatment was observed in situ, and the effect of single-pass rolling reduction on it was investigated. In uneven hot-rolled microstructure, the millimeter-grade elongated grains (MEGs) possessed an extremely large size and a high Schmid factor for slip compared to the fine grains, which led to greater plastic deformation and increased dislocation density and deformation energy storage during single-pass rolling. During subsequent solution treatment, there were fewer nucleation sites for the new grain, and the grain boundary (GB) was the main nucleation site in MEGs at a lower rolling reduction. In contrast, at a higher reduction, increased uniformly distributed rolling deformation and more nucleation sites were developed in MEGs. As the reduction increased, the number of in-grain nucleation sites gradually exceeded that of GB nucleation sites, and in-grain nucleation preferentially occurred. This was beneficial for promoting the refinement of new recrystallized grains and a reduction in the size difference of new grains during recrystallization. The single-pass rolling reduction of 15-20% can effectively increase the nucleation sites and improve the uniformity of rolling deformation distribution in the MEGs, promote in-grain nucleation, and finally refine the abnormally coarse elongated grain, and eliminate the mixed-grain structure after solution treatment.

[Value of Doppler color echocardiography in diagnosis of Kawasaki disease with cardiac involvement].

OBJECTIVE: To assess the diagnostic value of Doppler color echocardiography for Kawasaki disease (KD) with cardiac involvement. METHODS: Doppler color echocardiography was performed in 58 KD cases for measurement of the diameter of the coronary artery and the dimensions of the ventricles. The ejection fraction (EF) of the heart was also calculated and the presence of pericardial effusion and valvular regurgitation examined. RESULTS: Cardiac involvement was identified in 31 (53.45%) of the total 58 patients, and 28 patients were found to have coronary artery lesions. Uncomplicated left and right main stem coronary artery lesions were detected in 17 and 3 patients, respectively, lesions involving both two coronary arteries in 8, coronary aneurysms in 2, left ventricle enlargement in 9, right ventricle enlargement in 6, and enlargement of the whole heart in 4 patients. Eighteen patients had mitral regurgitation, 16 had tricuspid regurgitation, 13 had pericardial effusion, and 2 developed temporary cardiac dysfunction. CONCLUSIONS: Doppler color echocardiography is capable of depicting dynamically the pathological changes and progression of the coronary artery lesions with prognostic indications, to serve as the most valuable non-invasive modality for diagnosis of KD with cardiac involvement.

[Diagnostic value of color echocardiography in neonatal cyanotic congenital heart disease].

OBJECTIVE: To study the value of color echocardiography in diagnosis of neonatal cyanotic congenital heart disease (NCHD). METHOD: A total of 149 cyanotic neonates were examined by color echocardiography, of whom 25 were diagnosed having NCHD and analyzed for classification. RESULTS: Such complex deformities as transposition of the major arteries, tetralogy of Fallot, single ventricle, persistent truncus arteriosus were found in these 25 cases of NCHD, of which major artery transposition was the most common defects, followed by tetralogy of Fallot and then by single ventricle. CONCLUSION: Color echocardiography can be used routinely in diagnosis of congenital heart disease of cyanotic neonates.