Al-B-C ternary compounds : synthesis, structure, composition and thermal stability

International audienc

Al-B-C ternary compounds : synthesis, structure, composition and thermal stability

International audienc

Low temperature (down to 450° C) annealed TiAl contacts on N-type gallium nitride characterized by differential scanning calorimetry

International audienceThis work reports on Differential Scanning Calorimetry (DSC) measurements performed on Ti-Al metallic layers stacks deposited on n+-GaN. The aim is to get better understanding of the mechanisms leading to ohmic contact formation during the annealing stage. Two exothermic peaks were found, one below 500°C and the other one around 660°C. They can be respectively attributed to Al3Ti and Al2Ti compounds formation. The locations of these peaks provide clear evidence of solid-solid reac-tions. Lowest contact resistance is well correlated with the presence of Al3Ti compound, corresponding to Al(200nm)/Ti(50nm) stoichiometric ratio. Subsequently, Al(200 nm)Ti(50 nm) stacks on n+-GaN were annealed from 400°C to 650°C. Specific Contact Resistivity (SCR) values stay in the mid 10-5 Ω.cm² range for annealing temperatures between 450°C and 650°C. Such low-temperature annealed contacts on n+-GaN may open new device processing routes, simpler and cheaper, in which Ohmic and Schottky contacts are annealed together

Monolithes de silice et de carbone à porosité hiérarchisée obtenus par frittage SPS

La silice SBA-15 et le carbone CMK-3 possèdent une grande surface spécifique et un volume important de mésopores ordonnés dans une symétrie hexagonale (groupe d’espace p6 mm). Il est nécessaire de préserver leurs caractéristiques lors de la mise en forme de ces matériaux, pour un grand nombre d’applications. Le frittage SPS (Spark Plasma Sintering) des poudres a été effectué sans charge ou avec une charge uniaxiale de 25 MPa et à des températures de 600 à 800 ◦C pour la silice et 1100 à 1300 ◦C pour le carbone, pendant 5 minutes. Les isothermes d’adsorption/désorption d’azote montrent que les monolithes obtenus conservent une surface spécifique élevée (300 à 500 m2/g) et un volume mésoporeux de l’ordre de 0,7 cm3/g. La coexistence de la mésoporosité et d’une macroporosité interconnectée de volume voisin est observée par MEB (Microscopie Électronique à Balayage) et MET (Microscopie Électronique en Transmission). En outre, l’organisation de la mésoporosité est partiellement maintenue comme le mettent en évidence la DRX (Diffraction des Rayons X) et la MET

Subarachnoid hemorrahage in a young patient with a factor V Leiden thrombophilia: Case report and literature review

Introduction: Cerebral venous thrombosis, including thrombosis of cerebral veins and major dural sinuses, is an uncommon disorder in the general population. However, it has a higher frequency among patients younger than 40 years old, patients with thrombophilia, and women who are pregnant or receiving hormonal contraception. The annual incidence is estimated to be 3 to 4 cases per million. Coexisting cerebral vein thrombosis and aneurysmal disease in the setting of acute subarachnoid hemorrhage is exceedingly rare. These rare situations put difficult problems of diagnosis and treatment. Case Report: We present the case of a 42-year-old man patient who was diagnosed with thrombophilia of heterozygous factor V Leiden mutation and right ischemic stroke internal carotid cerebral artery four years ago. The patient presented with nausea, vomiting, a progressive severe headache that had lasted for a few days, followed by a rapid deterioration in the level of consciousness.On admission, the patient was in a comatose state, GCS score 5, mydriasis with bilaterally preservation of fotomotor reflex, stiff neck, acute respiratory failure and vegetative disorder. Cerebral CT scan showed a acute tetraventricular hydrocephalus and subarachnoid hemorrhage and cerebral four vessels angiography showed an left posterior communicating artery aneurysms and complete occlusion of right internal carotid artery.The aneurysm was managed with endovascular coiling with 100% occlusion achieved and acute hydrocephalus was treated first with external ventricular drainage and in a second time with ventriculoperitoneal shunt.The immediate and late outcome of patient has been addicted to several complications: acute bacterial meningitis, left hemiparesis, bronchopneumonia, urinary infection, malfunction of external ventricular drainage end swallowing disorders. Conclusion: In this report, the authors discuss the case of a coexistence ruptured aneurysm of the left posterior communicating artery in one patient known with factor V Leiden thrombophilia and proximal right ICA occlusion.This associated is more rare and dangerous, but curable disease. The case clearly illustrates both the difficulty in establishing the cause of subarachnoid hemorrhage in the presence of both aneurismal and CVST disease as well as the initiation of post-endovascular coil embolization anticoagulation therapy. Endovascular coil embolization of the aneurysm was thus undertaken, with subsequent heparin anticoagulation to attempt to prevent thrombus propagation.This neurosurgical strategy for treatment of a patient conducted to excellent results

Choledocoscopy in the surgery of mechanical jaundice

Universitatea de medicina si farmacie “Gr. T. Popa”, Iasi, clinica a IV-a chirurgie, Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Scopul lucrării: Diversitatea etiopatogenică a icterului mecanic justifică explorarea coledocoscopică, necesară unui diagnostic de certitudine. Material şi metodă: Între anii 2002 - 2011 am utilizat coledocoscopul flexibil la 58 de pacienți internați cu icter mecanic. La 21 (36,2 %) dintre aceştia icterul s-au dovedit a fi de etiologie neoplazică: 5 (8,6 %) cazuri cu ampulom vaterian (care au beneficiat de duodenopancreatectomie cefalică), 14 (24,1 %) cazuri cu neoplasm al capului de pancreas şi două (3.4 %) cazuri cu colangiocarcinom). Ceilalți 37 (63,8 %) de pacienți au avut o etiologie litiazică, la care coledocolitotomia asistată coledocoscopic şi asociată colecistectomiei a permis vindecarea. Rezultate. Discuții: Dintre pacienții cu suspiciune de icter mecanic neoplazic, în două (3,4 %) cazuri a fost necesară coledocoscopia care a certificat diagnosticul de colangiocarcinom atât prin aspectul imagistic, dar mai ales datorită posibilității prelevării biopsiei şi examenului histopatologic. În explorarea icterului mecanic. cu etiologie litiazică examenul coledocoscopic permite vizualizarea calculilor în 16 (27,5 %) cazuri la care celelalte explorări imagistice erau neconcludente. În toate cazurile controlul coledocoscopic a certificat absența calculilor în calea biliarặ principalặ la finalul intervenției, oferind astfel siguranță privind acuratețea actului chirurgical. Concluzii: Coledocoscopia aduce siguranță în chirurgia căii biliare principale atât în ceea ce priveşte diagnosticul, permițând vizualizarea şi prelevarea biopsiei în leziunile tumorale ale căii biliare principale cât şi în tratamentul litiazei biliare, oferind posibilitatea controlului imediat (intraoperator) al căii biliare principale după coledocolitotomie.Abstract. Background. The diverse etiology of mechanical jaundice requires a choledocoscopy to allow a correct diagnosis. Methods: Between 2002 and 2011, we used flexible choledocoscope, in 58 patients with mechanical jaundice admitted in our clinic. 21 (36, 2 %) cases proved to be of neoplastic etiology: 5 (8, 6%) cases diagnosed with vaterian ampuloma (treated by cephalic duodenopancreatectomy), 14 (24, 1 %) cases with pancreatic head cancer and two (3, 4 %) cases with cholangiocarcinoma. The remaining 37 (63, 8 %) cases were caused by lithiasis, treated by choledocolhitotomy associated with choledocoscopy and cholecystectomy. Results. Discussion: Among patients with suspected neoplastic mechanical jaundice, in two (3.4 %) cases choledocoscopy was necessary, in order to sustained the diagnosis of colangiocarcinoma, by macroscopically appearance, and also by the biopsy sampling and histological examination. In mechanical jaundice of lithiasis etiology, the choledocoscopy permitted the visualization of stones in 16 (27, 5%) cases in which, other imagistic investigations were inconclusive. In all cases choledocoscopic control certified the absence of gallstones in the bile duct at the end of the surgical procedure, and thereby provides safety of the surgical act. Conclusions: Choledocoscopy adds certainty in the main bile duct surgery both in terms of correct diagnosis, allowing visualization and biopsy sampling of the main bile duct in tumor lesions and in treatment of gallstone disease, allowing immediate control of the main bile duct after choledocolithotomy

Beta-lactam-induced immediate hypersensitivity reactions: A genome-wide association study of a deeply phenotyped cohort

Background β-lactam antibiotics are associated with a variety of immune-mediated or hypersensitivity reactions, including immediate (Type I) reactions mediated by antigen-specific IgE. Objective To identify genetic predisposing factors for immediate reactions to β-lactam antibiotics. Methods Patients with a clinical history of immediate hypersensitivity reactions to either penicillins or cephalosporins, which were immunologically confirmed, were recruited from allergy clinics. A genome-wide association study (GWAS) was conducted on 662 patients (the discovery cohort) with a diagnosis of immediate hypersensitivity and the main finding was replicated in a cohort of 98 Spanish cases, recruited using the same diagnostic criteria as the discovery cohort. Results GWAS identified rs71542416 within the Class II HLA region as the top hit (P = 2x10-14); this was in linkage disequilibrium with HLA-DRB1*10:01 (OR = 2.93 P = 5.4x10-7) and HLA-DQA1*01:05 (OR=2.93, P=5.4x10-7). Haplotype analysis identified that HLA-DRB1*10:01 was a risk factor even without the HLA-DQA1*01:05 allele. The association with HLA-DRB1*10:01 was replicated in another cohort, with the meta-analysis of the discovery and replication cohorts showing that HLA-DRB1*10:01 increased the risk of immediate hypersensitivity at a genome-wide level (OR = 2.96 P=4.1x10-9). No association with HLA-DRB1*10:01 was identified in 268 patients with delayed hypersensitivity reactions to β-lactams. Conclusion HLA-DRB1*10:01 predisposed to immediate hypersensitivity reactions to penicillins. Further work to identify other predisposing HLA and non-HLA loci is required. Clinical implications This novel insight into the mechanisms of immediate reactions associated with penicillins may be of use in risk stratifying patients where penicillin cannot be excluded as an etiological agent