Redo operation after surgery for aortic aneurysm and dissection

Thirteen patients who underwent redo operation after surgical treatment of aortic aneurysm and dissection were presented. In 8 patients, redo operations were performed for aortic dissection following aortic valve replacement. A-C bypass, the Koster-Collins operation and replacement of thoracic aorta. In the other 5 patients, the reasons for redo operation were aortic root enlargement after replacement of ascending aorta and aortic valve replacement, pseudoaneurysm and aneurysmal dilatation around coronary button for the Bentall operation and recurrent aneurysm after patch aortoplasty and thoracoabdominal replacement using the Crawford's maneuver. To prevent these redo operation, adequate selection of surgical procedures and meticulous operative techniques should be required in primary operation.     

High field-effect mobility normally-off AlGaN/GaN hybrid MOS-HFET on Si substrate by selective area growth technique

The paper reports a normally-off n-channel AlGaN/GaN hybrid metal-oxide-semiconductor heterojunction field-effect transistor (MOS-HFET) on Si substrate with high field-effect mobility. To decrease the channel resistance and to improve the field-effect mobility, of the MOS-HFET, a selective area growth (SAG) technique is applied at the channel region. The fabricated MOS-HFET exhibits a good normally-off operation with the threshold voltage of 3.7 V, the specific ON-state resistance of 7.6 mΩ cm², and the breakdown voltage of over 800 V.     

Iodine-131 and other radionuclides in environmental samples collected from Ibaraki/Japan after the Chernobyl accident

Measurements were made of 131I, 137Cs, 134Cs and 103Ru in environmental samples collected from Ibaraki-Prefecture, Japan, after the Chernobyl accident. The highest values of 131I obtained in May 1986 were 98 Bq l-1 (2.7 nCi l-1) for rain water (collected at the beginning of the rainfall), 400 Bq kg-1 (11 nCi kg-1) for pine needles (wet), 160 Bq kg-1 (4.3 nCi kg-1) for vegetables (wet) and 52 Bq kg-1 (1.4 nCi kg-1) for seaweed (wet). Most of the radioiodine in rain water was present as IO3- and I-. The proportion of IO3- in fresh rain water was higher than that of I-, but the IO3- was converted to I- during storage. About 10% of 131I was removed from leaf vegetables by washing, and about 70% by boiling.