We investigated the effect of SiC doping on the critical current density (Jc) in MgB2 thick films using amorphous SiC impurity layers of various thicknesses: 7, 14, 35, and 70 nm. SiC impurity layers were first deposited on the Al2O3(0001) substrates at room temperature by using a pulsed laser deposition system, after which MgB2 films were grown on the SiC deposited precursor substrates by using a hybrid physical–chemical vapor deposition technique at a low growth temperature of 480 °C. All samples showed a high transition temperature of ∼40 K irrespective of the thickness of the impurity layer. The grain sizes of the MgB2 films slightly increased from 400 to 488 nm with increasing thickness of the impurity layer. The MgB2 thick film with a 35 nm thick SiC impurity layer exhibited the highest Jc, while all SiC doped samples showed a higher Jc than a pure MgB2 thick film throughout the whole magnetic field region. These results suggest that the SiC particles of the impurity layer diffused into the MgB2 films during film growth, and the SiC particles, along with the columnar grain boundaries in the MgB2 thick films, act as strong pinning centers.

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Background/Introduction Although pericardiectomy is an effective treatment of constrictive pericarditis (CP), clinical outcome is not always successful. Pericardial calcification is a unique finding in CP. However, the amount and localization of calcification vary. Computer tomography (CT) can visualize the pericardial calcification with high sensitivity and provide the anatomical assessment. Purpose We investigated that how the pattern and amount of pericardial calcification affect the mid-term postoperative outcome after pericardiectomy in CP. Methods All of the patients who underwent total pericardiectomy in our hospital from 2010 to 2020 were derived from electrical medical records (n=105). Among them, preoperative CT scans (non-gated non-contrast) of 98 patients were available and, thus, 98 consecutive patients were finally analyzed. Medical records were reviewed in a retrospective manner. Cardiovascular event is defined as cardiovascular death or hospitalization associated with a heart failure symptom and all cause event is defined as all events that require admission. CT scan was analyzed by Aquarius Workstation, and the volume and localization pattern of pericalcification were derived. Pericardium calcium score was given as an Agatston score. Results Of 98 patients, 25 (25.5%) patients were hospitalized with heart failure symptom after pericardiectomy. Median follow up duration of patients is 172 weeks. A group with cardiovascular event had higher NYHA grade (P<0.001), lower calcium volume (P=0.004), and lower calcium score (P=0.01). Multivariate cox proportional analysis showed that high ln(calcium score) before pericardiectomy was dependent predictor of cardiovascular event (hazard ratio, 0.90; P=0.04) and all cause event (hazard ratio, 0.91, P=0.04) after pericardiectomy. When we set the cut off value at 7.22, based on ROC curve, there was a significant difference in cardiovascular event between the groups divided by this cutoff value in Kaplan-Meier curve (P=0.002) and multivariate cox proportional analysis (P=0.04). In the subgroup analysis, myocardium invasion and circumferential calcification were more common in the high calcium score group. Idiopathic & tuberculosis pericarditis were more associated with high calcium score group and post-operative pericarditis, other reasons (infection, radiation, etc) were more associated with low calcium group. Conclusion Low burden of pericardial calcification was associated high rate of mid-term clinical event after pericardiectomy CP. Preoperative evaluation of pericardial calcification pattern can be used as predictor of postoperative outcomes. Funding Acknowledgement Type of funding sources: None.