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Two samples of high purity InP extracted from the same wafer were examined by positron annihilation spectrum analysis after having been, processed by means of thermal Neutron Transmutation Doping (NTD). Compared with the as grown sample with an average positron lifetime of 246 ps at 300 K, the high dose doped one has an average lifetime of 251 ps and the lower dose doped one 248 ps measured under the same condition, indicating that some defects have been introduced in the NTD process. Annealing experimental results show a steady decrease in the average lifetime with increasing annealing temperature up to 550°C. And a peak in lifetime curve around 500°C was observed which may be attributed to defects related structure conversion. Temperature experiments conducted on the low dose doped sample from 150K to 290 K suggest the existence of vacancy-impurity complex which have given rise to an abnormal reduction of average lifetime with increasing temperature. Also a n-type InP sample (A61) was irradiated with thermal neutrons in another reactor and the lifetime results display an increase of 15 ps. Furthermore, to study epithermal neutron irradiation effects on InP, measurements were performed on an n-type InP sample (N119) along with one p-type sample (P118) after having been irradiated with high fluence of epithermal neutrons. The former has an average lifetime of 262 ps and the latter 247 ps after irradiation. The results prove that on some occassion epithermal neutrons can produce sizable defects in InP.

Current surgery to treat acute type A aortic dissection involving an intimal tear in the ascending aorta consists of resection and replacement, but mortality is high. We report the case of a 46-year-old female patient with Marfan syndrome who presented with excruciating retrosternal pain and breathing distress after a bowel movement with stress. Magnetic resonance imaging and multicolour sonography showed type A aortic dissection extending from the aortic root to the right iliac artery, with intimal tears in the ascending aorta above the sinotubular junction, the distal arch beyond the left subclavian artery and the isthmic region. We adapted the endoluminal stenting technique to this case of type A aortic dissection by sealing the intimal tears in the ascending aorta using endovascular introduction of one endoluminal graft, as confirmed on angiography. The patient was discharged after 10 days. Follow-up examination by computed tomography after more than 1 year revealed no sign of dissection at any level of the aorta.