Growth, Electronic and Electrical Characterization of Ge-Rich Ge-Sb-Te Alloy.

In this study, we deposit a Ge-rich Ge-Sb-Te alloy by physical vapor deposition (PVD) in the amorphous phase on silicon substrates. We study in-situ, by X-ray and ultraviolet photoemission spectroscopies (XPS and UPS), the electronic properties and carefully ascertain the alloy composition to be GST 29 20 28. Subsequently, Raman spectroscopy is employed to corroborate the results from the photoemission study. X-ray diffraction is used upon annealing to study the crystallization of such an alloy and identify the effects of phase separation and segregation of crystalline Ge with the formation of grains along the [111] direction, as expected for such Ge-rich Ge-Sb-Te alloys. In addition, we report on the electrical characterization of single memory cells containing the Ge-rich Ge-Sb-Te alloy, including I-V characteristic curves, programming curves, and SET and RESET operation performance, as well as upon annealing temperature. A fair alignment of the electrical parameters with the current state-of-the-art of conventional (GeTe)n-(Sb2Te3)m alloys, deposited by PVD, is found, but with enhanced thermal stability, which allows for data retention up to 230 °C.

Radiation Hardness of 4H-SiC P-N Junction UV Photo-Detector.

4H-SiC based p-n junction UV photo-detectors were irradiated with 600 keV He+ in the fluence range of 5 × 1011 ÷ 5 × 1014 ion/cm2 in order to investigate their radiation hardness. The effects of irradiation on the electro-optical performance were monitored in dark condition and in the UV (200 ÷ 400 nm) range, as well as in the visible region confirming the typical visible blindness of unirradiated and irradiated SiC photo-sensors. A decrease of UV optical responsivity occurred after irradiation and two fluence regimes were identified. At low fluence (<1013 ions/cm2), a considerable reduction of optical responsivity (of about 50%) was measured despite the absence of relevant dark current changes. The presence of irradiation induced point defects and then the reduction of photo-generated charge lifetime are responsible for a reduction of the charge collection efficiency and then of the relevant optical response reduction: point defects act as recombination centers for the photo-generated charges, which recombine during the drift/diffusion toward the electrodes. At higher irradiation fluence, the optical responsivity is strongly reduced due to the formation of complex defects. The threshold between low and high fluence is about 100 kGy, confirming the radiation hardness of SiC photo-sensors.

Penetrating aortic injury left untreated for 20 days: a case report.

BACKGROUND: Penetrating aortic trauma remains one of the most challenging injuries with a high mortality rate if left untreated, or if the surgical treatment is delayed. We present an uncommon case of a late diagnosed abdominal firearm injury, in which the bullet partially penetrated the wall of the aorta, creating a plug that prevented immediate death due to massive bleeding. CASE PRESENTATION: A 26-year-old Libyan man was a victim of a firearm wound, with a bullet penetrating his abdominal wall from the left to right side. After the assault, the victim, spent up to 20 days crossing the Mediterranean Sea to leave his country of origin. Abdominal radiography revealed the presence of a bullet located anteriorly to the second lumbar vertebra, while computed tomography angiography, unexpectedly, demonstrated that the bullet penetrated partially into the aortic wall at the level of the left renal artery. The bullet penetrated the aortic wall for half of its length, creating a plug that avoided immediate life-threatening bleeding at the time of the gunshot injury. The bullet was removed and the aortic lesion was repaired. The patient was discharged 6 days after the surgical procedure, in good health. CONCLUSIONS: We presented a very rare case of late diagnosis of aortic injury caused by a gunshot lesion, in which the particular trajectory of the bullet helped avoid immediate life-threatening bleeding and, probably, saved the patient's life.

Surgical Treatment of Residual Distal Intimal Flap during Eversion Carotid Endarterectomy.

BACKGROUND: Eversion carotid endarterectomy (ECEA) is an effective surgical technique for the treatment of internal carotid artery (ICA) stenosis. However, a residual distal intimal flap may determine a higher rate of neurological complications. The treatment of DIF may be challenging, and no definitive approach has been described. We describe a simple surgical option for the treatment of DIF. METHODS: After internal ECEA has been performed, stitches are positioned at the side of intimal flap. Suture sequence is performed from internal-external-external-internal artery wall including the everted ICA, maintaining the suture thread inside the vessel. Once the ICA is correctly repositioned, the suture thread is pulled out. Once the standard carotid anastomosis has been performed, the flap is finally tacked. RESULTS: Fifteen patients have undergone surgical repair of DIF with the modified technique. No patients developed neurological complications after the surgical procedure, and all patients are still alive at last follow-up visit. CONCLUSIONS: This simple technique seems a safe and feasible surgical option to correct DIF, avoiding challenging surgical procedures that may increase operative and clamping time.

Influence of hydrofluoric acid treatment on electroless deposition of Au clusters.

The morphology of gold nanoparticles (AuNPs) deposited on a (100) silicon wafer by simple immersion in a solution containing a metal salt and hydrofluoric acid (HF) is altered by HF treatment both before and after deposition. The gold clusters are characterized by the presence of flat regions and quasispherical particles consistent with the layer-by-layer or island growth modes, respectively. The cleaning procedure, including HF immersion prior to deposition, affects the predominantly occurring gold structures. Flat regions, which are of a few tens of nanometers long, are present after immersion for 10 s. The three-dimensional (3D) clusters are formed after a cleaning procedure of 4 min, which results in a large amount of spherical particles with a diameter of ≈15 nm and in a small percentage of residual square layers of a few nanometers in length. The samples were also treated with HF after the deposition and we found out a general thickening of flat regions, as revealed by TEM and AFM analysis. This result is in contrast to the coalescence observed in similar experiments performed with Ag. It is suggested that the HF dissolves the silicon oxide layer formed on top of the thin flat clusters and promotes the partial atomic rearrangement of the layered gold atoms, driven by a reduction of the surface energy. The X-ray diffraction investigation indicated changes in the crystalline orientation of the flat regions, which partially lose their initially heteroepitaxial relationship with the substrate. A postdeposition HF treatment for almost 70 s has nearly the same effect of long duration, high temperature annealing. The process presented herein could be beneficial to change the spectral response of nanoparticle arrays and to improve the conversion efficiency of hybrid photovoltaic devices.

Endovascular repair of bilateral common iliac artery aneurysms using GORE Excluder iliac branch endoprosthesis without aortobi-iliac stent graft conjunction: A case report.

INTRODUCTION: Bilateral common iliac artery (CIA) aneurysm (CIAA) is a rare entity. In the past decade, different endovascular approaches have been adopted for patients with several comorbidities or unfit for open repair (OR). Recently, the use of iliac branch stent graft has been proposed, resulting in satisfactory patency rates and decrease in morbidity. Currently, according to instruction for use, the iliac branch stent graft is to be used with aortobi-iliac stent graft conjunction. We describe a case of a successful endovascular repair of bilateral CIAAs using the GORE Excluder iliac branch endoprosthesis (IBEs) without aortobi-iliac stent graft conjunction. CASE PRESENTATION: An 83-year-old man was admitted with abdominal pain and presence of pulsatile mass in the right and left iliac fossa. Computed tomographic (CT) angiography showed the presence of large bilateral CIAAs (right CIA = 66 mm; left CIA = 38 mm), without concomitant thoracic or abdominal aorta aneurysm. Moreover, CT scan demonstrated the presence of bilateral lower accessory renal artery close to the aortic bifurcation. Due to the high operative risk, the patient was scheduled for endovascular repair with bilateral IBEs, without the aortobi-iliac stent graft conjunction to avoid the renal ischemia as a consequence of renal arteries covering. The procedure was completed without complications and duplex ultrasound demonstrated the complete exclusion of both aneurysms without any type of endoleaks at 1 month of follow-up. CONCLUSIONS: GORE IBEs without aortobi-iliac stent graft conjunction seem to be a feasible and effective procedure for the treatment of isolated CIAAs in patients with highly selected anatomical conditions.

Non-mycotic anastomotic pseudoaneurysm of renal allograft artery. Case Report.

UNLABELLED: Vascular complications after kidney transplantation are uncommon, and in most cases they present in the early post-transplant period. Anastomotic pseudo-aneurysms usually involve the renal transplant artery anastomosis and in most cases are the consequence of a mycotic contamination during organ recovery or handling of the graft. We report the case of a 61 year-old woman, who presented, eight months after successful kidney transplantation from a deceased donor, with mild pain in the right iliac fossa. Graft sonography and computed tomography scan demonstrated a 33-mm pseudo-aneurysm of the transplant renal artery at the anastomotic site with the external iliac artery. The patient underwent an emergent surgical intervention with resection of the pseudo-aneurysm. Renal transplant artery was re-perfused with a by-pass with the internal iliac artery, while the common iliac artery was revascularized through an autologous vein by-pass between the proximal external iliac artery and the common femoral artery. Postoperative course was complicated by inguinal lymphorrea, with complete resolution on postoperative day 22. Histopathologic examination of the pseudo-aneurysm wall did not reveal any sign of mycotic infection. At 6-month follow-up, graft function was stable and graft sonography demonstrated the patency of iliac-femoral by-pass and a normal renal graft perfusion. In conclusion, pseudo-aneurysm of the renal transplant artery is a rare but potentially life-threatening complication of kidney transplantation, occurring even in the late post-transplant period. Surgical resection of the pseudo-aneurysm, although challenging, may be a valuable option for definitive treatment of the pseudo-aneurysm, while preserving the renal graft function. KEY WORDS: Aneurysm, Deceased donor, Kidney transplantation, Pseudo-aneurysm, Renal artery Surgery, Vascular complications.

Endovascular Treatment of Chronic Occluded Popliteal Artery Aneurysm.

Critical limb ischemia may be the consequence of chronic occlusion of an aneurysm of popliteal artery. Endovascular repairs have the potential to be less invasive than open surgery and to allow the treatment, during the same procedure, of occlusive infrapopliteal diseases achieving a better distal outflow. Eleven patients with occluded popliteal artery aneurysm (PAA) underwent an endovascular repair of PAA using a new technique, by positioning of a Viabahn graft inside a bare nitinol stent, deployed at the level of aneurysm with the intent to avoid distal embolization and to assure an external scaffold for the Viabahn graft. Immediate success rate was 100%. A peroneal artery embolization occurred in 1 patient (9%) and was successfully treated by stent implantation. Four (36.4%) patients needed a below-the-knee revascularization to achieve at least 1 vessel line to the foot. Mean postoperative hospital stay was 2.6 days. At 24-month follow-up, primary patency, target lesion revascularization, and major amputation rates were 82%, 9%, and 0%, respectively. All patients are still alive at last follow-up visit. The endovascular repair with the combined use of a bare metal stent and Viabahn graft resulted in a low incidence of distal embolization and major amputation rate, with an excellent 24-month patency rate, and may offer a safe alternative to open surgery for the treatment of occluded PAAs.

Venae comitantes as a potential vascular resource to create native arteriovenous fistulae.

PURPOSE: The arteriovenous fistula (AVF) represents the gold standard for hemodialysis (HD) vascular access. In some critical cases, use of the deep venous circle may represent an alternative approach and venae comitantes could be employed for this purpose. METHODS: Sixty patients with chronic renal failure in which the deep venous circle was used to create an AVF were identified; of the 48 who had a direct anastomosis between the brachial artery and vena comitans, 42 had a long-term follow-up (mean follow-up 59 weeks), while six were lost to follow-up. RESULTS: Immediate success (patency and palpable thrill) was achieved in 88% of cases (primary and early failure 12%). Primary accessibility rate was 62%, while 11 patients required a second surgical approach to make the vein accessible to needling. Secondary accessibility rate of 71% was due to surgical revisions. In the 80-week observation period, the complication rate was 10% with irreversible loss of the AVF in all these cases. Cumulative patency was 71% at the 80th week. Including all 42 patients, technical and functional success rate, defined as vein accessibility to needling and chance of an adequate HD treatment, was 62%. CONCLUSIONS: AVF employing venae comitantes may represent a suitable alternative in the absence of other vascular accesses for HD.

Off-pump myocardial revascularization. The single-suture technique: how to avoid any complication.

INTRODUCTION: Coronary artery bypass grafting without cardiopulmonary bypass (CPB) is now an accepted technique of complete myocardial revascularization. The technique was originally described by Kolesov [Kolesov 1967] and later abandoned when the CPB became the gold standard for cardiac operations on the arrested heart. In the late 1980s off-pump coronary grafting was reintroduced by Benetti and Buffolo with very encouraging results, especially for high-risk patients [Benetti 1985, Buffolo 1996]. This technique was limited to the grafting of left anterior descending (LAD) coronary artery and sometimes to the right coronary artery (RCA) [Benetti 1985, Buffolo 1996]. In recent years, technical advantages in coronary exposure and mechanical stabilization have come from the industry, leading to the possibility of a complete off-pump myocardial revascularization. The exposure of coronary arteries in the circumflex territory has been described by Ricardo Lima from Brazil. He described a series of four sutures on the pericardium, which allowed a good exposure of such surgically difficult territory. Tomas Salerno simplified the "Lima sutures" with a technique using a single suture placed in the oblique sinus of the posterior pericardium, which allowed a good exposure of the circumflex territory and less heart manipulation. [Bergsland 1997, Salerno 1999, Ricci 2000]. This deep pericardial suture may injure the organs situated just behind the pericardium, such as the esophagus and thoracic aorta [Ricci 2000], and several complications have been reported in literature: injury of the left lower pulmonary vein has resulted in post-operative bleeding and dangerous hematoma behind the left atrium [Fukui 2002]; and subcutaneous emphasema has been detected in several cases in our experience. We report a different way to pose the single lima suture in order to avoid any damage to the structures behind the posterior pericardium.