Controllable disorder in a hybrid nanoelectronic system: realization of a superconducting diode.

We have studied a hybrid nanoelectronic system which consists of an AlGaAs/GaAs two-dimensional electron gas (2DEG) in close proximity (~70 nm) to an Al superconducting nanofilm. By tuning the current through the Al film, we can change the conductance of the 2DEG and furthermore vary the effective disorder in the Al superconducting film in a controllable way. When a high current is injected into the film, screening which couples the Al film and the 2DEG results in a collapse of anti-symmetric behavior in the current-voltage characteristics, V(I) ~ -V(-I), which holds true in a conventional superconductor. Our results may open a new avenue of experimentally realizing a superconducting diode.

[Duplication of the alimentary tract: report of three cases].

Three cases of duplications of the alimentary tract are presented. Case 1 was a 5-month-old male baby. He was admitted due to copiously painless rectal bleeding. Tc-99m pertechnetate scanning revealed unusual tubular and spherical lesions. Laparotomy findings were that a tubular ileal duplication m assured 100cm or so in length and communicated with ileal lumen by its distal orifice. Moreover, there were 2 spherical duplications like ping-pong ball in morphology located in neighboring mesentery. Case 2 was a 2-day-old male newborn. He was admitted because of persistent bilious vomiting on his second day of life. Plain film x-ray revealed dilated stomach and scanty bowel gas. Laparotomy finding was that a cystic duplication measured 1.5cm in length which located in and obstructed the lumen of proximal jejunum. Also there was a distal orifice of duplication in communication with jejunal lumen. Case 3 was a 4-year-and-4-month-old boy who admitted after intermittently non-projectile vomiting for a period of 1 1/2 year. Sonography showed a calcification lesion at right upper quadrant of abdomen. Panendoscopy saw a refraction at second part of duodenum. The findings of laparotomy were that 2 tumor masses laid upon gastrocolic ligament. One was ossified soft tissue (gastrocolic ligament) with 1.5 x 1 x 0.8cm3 in size, and the other was cystic duplication of transverse colon in contact with beneath mesocolon. All duplications of 3 cases were lined with ectopic gastric and small intestinal mucosa, and ulcerative lesion was found in case 3 only. All lesions were resected and removed with good results.