Correlated Three-Dimensional Imaging of Dislocations: Insights into the Onset of Thermal Slip in Semiconductor Wafers.

Correlated x-ray diffraction imaging and light microscopy provide a conclusive picture of three-dimensional dislocation arrangements on the micrometer scale. The characterization includes bulk crystallographic properties like Burgers vectors and determines links to structural features at the surface. Based on this approach, we study here the thermally induced slip-band formation at prior mechanical damage in Si wafers. Mobilization and multiplication of preexisting dislocations are identified as dominating mechanisms, and undisturbed long-range emission from regenerative sources is discovered.

[Spontaneous dissection of the external iliac artery due to fibromuscular dysplasia]. / Spontane Dissektion der A. iliaca externa auf dem Boden einer fibromuskulären Dysplasie.

Spontaneous dissection of the external iliac artery due to fibromuscular dysplasia. A case of spontaneous dissection of the external iliac artery due to fibromuscular dysplasia is presented. In a 45-year-old man with a history of sudden onset of intermittent claudication a dissection of the right external iliac artery was found by duplex ultrasound. The patient, who was first treated with conservative therapy, subsequently required operative treatment because of further progression of the dissection. Considering the age of the patient a retrograde thrombendarterectomy manoeuver over guide wire was performed. Angiographic control at the end of operation demonstrated a good reconstructive result without any changes in the right common iliac artery and the aorta. Histopathological examination of the removed material showed fibromuscular dysplasia of the media. In the postoperative course the patient was clinically asymptomatic with ankle/brachial pressure indices of 1.0 on both legs. But shortly after discharge the intermittent claudication in the right leg recurred. Angiography and duplex ultrasound revealed focal stenosis of the right common iliac artery as well as retrograde dissection of the right common iliac artery extending into the distal aorta. Conservative therapy was recommended to the patient by the local hospital and no further progression of clinical and duplex findings within the last six months was found.

[Venous bypass: gold standard with excellent results]. / Der Venenbypass: Goldstandard mit überragenden Ergebnissen.

Since 1974 we have performed 1104 in situ vein bypasses for the reconstruction of femoropopliteal or femorotibial occlusions. The venous valves were made incompetent by using our Insitucut. An intraoperative completion angiography is mandatory. The primary cumulative patency rate is 93.5% at one year and 64.9% at five years. The permeability is depending on the quality of the outflow tract. The patency of femoropopliteal in situ bypasses with a three vessel runoff is 82.2% at five years, whereas bypasses with a single vessel runoff show a patency of 56%. The own results are comparable with the results of reversed and non-reversed vein bypasses given in the literature.

Direct reconstructive venous surgery.

Unilateral occlusions of the pelvic veins may be corrected by a Palma operation. In the classic Palma operation the contralateral long saphenous vein is suprapubicly led to the opposite side and is anastomosed end-to-end or end-to-side with the common femoral vein of the occluded side. Just lately, spirally wall reinforced PTFE grafts showed more favourable results than Palma grafts. Circumscribed occlusions of the superficial femoral vein can be interposed by the May-Husni operation. Thereby the ipsilateral long saphenous vein is implanted end-to-side into the popliteal vein. We perform the Palma operation as well as the May-Husni operation under the protection of a temporary av-fistula. The ascending venography only permits to make a statement on the morphological operability, whereas the functional operability is indicated by means of phlebodynamometry. Phlebodynamometry and plethysmography are the best means to judge the functional result of the operation which is of importance for the patient. The results of the Palma operation can be regarded as very satisfactory, provided that the morphological and functional indication for the operation was correct. The use of the endothelium protective operative technique by Robert Mays as well as the application of a temporary av-fistula yield a success that is above 80 p.c. As against that, the May-Husni operation achieves less than 50 p.c. success, even if a temporary av-fistula is established in the area of the ancle. Less favourable are the results obtained by direct restorative interventions on the subclavian vein, so that these operations should only be indicated in exceptional cases.