III-V heterostructure tunnel field-effect transistor.

The tunnel field-effect transistor (TFET) is regarded as one of the most promising solid-state switches to overcome the power dissipation challenge in ultra-low power integrated circuits. TFETs take advantage of quantum mechanical tunneling hence exploit a different current control mechanism compared to standard MOSFETs. In this review, we describe state-of-the-art development of TFET both in terms of performances and of materials integration and we identify the main remaining technological challenges such as heterojunction defects and oxide/channel interface traps causing trap-assisted-tunneling (TAT). Mesa-structures, planar as well as vertical geometries are examined. Conductance slope analysis on InAs/GaSb nanowire tunnel diodes are reported, these two-terminal measurements can be relevant to investigate the tunneling behavior. A special focus is dedicated to III-V heterostructure TFET, as different groups have recently shown encouraging results achieving the predicted sub-thermionic low-voltage operation.

[Biliary ileus: diagnosis and therapy]. / L'ileo biliare: aspetti diagnostici e terapeutici.

BACKGROUND: Gallstone ileus represents 1-3% of mechanical obstructions of the bowel. The surgical treatment performed in urgency has a mortality rates of 10-13% because galistone ileus is frequent in the elderly. Some diagnostic and therapeutic problems are debated in this paper. METHODS: 9 cases of gallstone ileus were analysed retrospectively in a series of 736 mechanical obstructions of the bowel submitted to surgery since 1969. The Authors report the clinical and physical data, the laboratory data and the results of the radiological procedures performed (plain abdominal X-ray, abdominal US, CT, MNR). The patients are stratified according to ASA system and the surgical treatment. The accuracy of the diagnostic procedures and the surgical mortality and morbidity are reported. RESULTS: The preoperative diagnosis was correct in 5 patients. History, clinical and laboratory findings are not specific. The plain abdominal X-ray was specific in 1/9 case, Us in 4/9, CT in 2/3, MNR in 1/1. 1 patient was included in ASA 1 class, 3 in ASA 2 class, and 5 in ASA 3 class. Enterolithotomy alone was performed in 3 cases and the one stage treatment (enterolithotomy and bilio-digestive fistula repair) in 6. No patient was submitted to two stage procedure because 2 of the patients submitted to enterolithotomy alone had a neoplastic fistula and 1 had a very high operative risk. No intraoperative mortality was registered. A wound infection developed in 4 patients. None of the patients had a recurrence of gallstone ileus. CONCLUSION: Evidence from this study supports one stage treatment when the diagnosis of gallstone ileus is correct because it is possible to delay the surgery and to perform a preoperative treatment to decrease the operative risk in the elderly. The correct preoperative diagnosis is often difficult but CT and MNR heve an high sensibility and specificity.

Ultrasound and Doppler features of accessory spleens and splenic grafts.

16 splenic grafts and 24 accessory spleens were evaluated with ultrasound, colour Doppler and power Doppler imaging, in order to compare the features of splenic grafts and accessory spleens. 12 splenic grafts (11 surgically implanted, 1 islet of splenosis) were detected in eight patients following splenectomy 6-12 months previously. Four of the surgically implanted splenic grafts were found in three patients following splenectomy 16-18 days previously. 21 accessory spleens were incidentally detected in 20 subjects who had not been operated upon, whereas three enlarged accessory spleens were found in 10 patients who underwent splenectomy 6-12 months previously. The size, shape, rim features, echogenicity, acoustic enhancement and vascularization of the splenic grafts and accessory spleens were evaluated. The splenic grafts were oval with lobulated margins, an inhomogeneous pattern in 36% and acoustic enhancement in 64%. Multiple feeding vessels arising from the surrounding tissue entered the periphery of 10 splenic grafts in the eight patients operated on 6-12 months previously, whereas no vascular signals were detected in the four splenic grafts of the three patients operated on 16-18 days ago. Accessory spleens were round with smooth echogenic margins and a vascular hilum arising from the splenic vessels. In conclusion colour Doppler and power Doppler allow differentiation between accessory spleens and splenic grafts basing on their shape and vascular supply.

Symptomatic lower limb varices secondary to Castleman's disease.

Although lower limb varices are very frequent, their association with Castleman's disease is extremely rare. We report a case of Castleman's disease involving the right inguinal lymph nodes with subsequent development of the symptoms caused by the compression of the great saphenous vein's gulf. The patient underwent surgical extirpation of the right inguinal mass, which successfully eliminated all the symptoms. The great saphenous vein was not stripped in order to leave an outlet for the deep venous blood flow in case of subsequent compression of the right femoral or iliac veins. This case confirms the effectiveness of surgical treatment in the localized form of Castleman's disease.

[Treatment of chronic pancreatitis today: considerations on 133 observed cases]. / Il trattamento della pancreatite cronica oggi: considerazioni su 133 casi osservati.

Aim of the work is to define the present role of surgery in the treatment of chronic pancreatitis and the criteria of choice of procedures. The authors examined retrospectively 133 patients. They analyze the clinical, laboratory and instrumental features on which has been formulated the surgical indications. Patients treated surgically were those who have intractable pain, jaundice, intestinal obstructions and bleeding. The choice of the procedure is based on the seat and type of the anatomo-pathological lesions and on the features of Wirsung's duct. 54 of the 133 patients observed have been treated surgically or with interventional radiology. The authors carried out 19 resections, 30 drainage procedures, 1 pancreatic biopsy, 2 percutaneous drainage, 1 perendoscopic papillotomy. Neither mortality nor morbidity were observed after radiological and endoscopic procedures, while after surgery we observed 3.9% of mortality and 9.4 of total morbidity and 5.6% of specific morbidity, represented by a pancreatic leakage. The long term results were well in the patients who didn't take on alcohol. In conclusion the authors underline that the progresses of the medical treatment and the radiological and endoscopic procedures imply the decrease of number of patients undergoing surgical intervention. They remind that surgery maintain his importance and, when carried out with correct indications, permits to obtain an effective and lasting result of the symptomatology presented by the patient.