A current-voltage model for double Schottky barrier devices

Schottky barriers are often formed at the semiconductor/metal contacts and affect the electrical behaviour of semiconductor devices. In particular, Schottky barriers have been playing a major role in the investigation of the electrical properties of mono and two-dimensional nanostructured materials, although their impact on the current-voltage characteristics has been frequently neglected or misunderstood. In this work, we propose a single equation to describe the current-voltage characteristics of two-terminal semiconductor devices with Schottky contacts. We apply the equation to numerically simulate the electrical behaviour for both ideal and non-ideal Schottky barriers. The proposed model can be used to directly estimate the Schottky barrier height and the ideality factor. We apply it to perfectly reproduce the experimental current-voltage characteristics of ultrathin molybdenum disulphide or tungsten diselenide nanosheets and tungsten disulphide nanotubes. The model constitutes a useful tool for the analysis and the extraction of relevant transport parameters in any two-terminal device with Schottky contacts

Ruptured middle cerebral artery aneurysms. retrospective study and multivariate analysis of 105 patients treated by surgical clipping

Objective of the study: We analyze in this study only patients with surgically treated ruptured aneurysms in order to identify statistical significance of each predictive factor in terms of outcome of patients with ruptured MCAAs. Materials and methods: In this retrospective study, we analyzed 105 cases of ruptured MCAAs, admitted from January 2001 to December 2015 at Neurosurgical Department of Umberto I University Hospital of Rome, Italy. Predictive factors evaluated are: Patient’s features (age, sex, co-morbidities), aneurysmal location (proximal, bifurcation or distal) and size of aneurysmal dome (small, large or giant); surgical timing (ultra-early, early, delayed), and Intracerebral Hemorrhage (ICH) volume. For each parameter we calculated mean and standard deviation, covariance and relation coefficient (through the linear regression model). Results: The clinical evaluation of patients assessed through the World Federation of Neurological Surgeons (WFSN) grading scale, that is 5 for 37 patients (35.3%), 4 for 28 patients. In 40% of cases the maximum sac diameter was between 7 mm and 12 mm, while in 67% of the cases the aneurysms concerned the bifurcation of the middle cerebral artery. ICH was associated in 57 cases (54.3%). As far as outcome is concerned, at 3 months, 32 patients (30.47%) had a favourable outcome, while 73 (69.52%) patients had not favourable outcome. To one year, 46 patients (43.8%) had favourable outcomes, while 59 patients (56.19%) had not favourable outcome. The mean outcomes as mean mRS are significantly less favourable in patients with ICH. Conclusion: In MCAAs patients, the presence of ICH strongly affects the outcome with a marked increase in mortality and morbidity. Surgical timing significantly influences the outcomes and ultra-early surgery should always be taken into account

Long term recurrence of solitary fibrous tumor involving vertebral body in thoracic spine. A case report

Solitary fibrous tumor (SFT) represents only 0.08% of all primary bone tumors and 0.1% of primary malignant bone tumors and rarely occurs in the spine. We present the case of a 56-year-old woman with long term recurrence (11 years) of spinal SFT involving T8 vertebral body. We performed a total resection of the lesion and spinal fusion T6-T11 with T8 titanium mesh and placement of pedicle screws in T6-T7 and T10-T11 connected by rods. Microscopic examination confirmed the recurrence of the WHO grade II solitary fibrous tumor. SFT is known for a late but common recurrence and uncertain behaviour. Gold standard treatment is Gross Total Resection. We believe that when vertebral bone is involved it is essential to perform a total excision with "supracomplete" resection if possible in order to avoid local recurrence, more difficult to treat due to an higher rate of perioperative complications. Periodical long-term follow-up is essential to allow early detection of relapses and to allow long-term survival

Antegrade selective cerebral perfusion and moderate hypothermia in aortic arch surgery: clinical outcomes in elderly patients†

OBJECTIVES To evaluate the outcome in elderly patients (≥75 years) undergoing elective aortic arch surgery with the aid of selective antegrade cerebral perfusion (SACP) and moderate hypothermic circulatory arrest (HCA). METHODS A series of 95 patients ≥75 years (median age 77 years, median EuroSCORE 28) undergoing elective aortic arch surgery with SACP and moderate HCA were analysed with regard to clinical outcome. Risk factors for serious adverse events (mortality, neurological injury) were determined. RESULTS Sixty-three patients (66%) underwent ascending aorta and hemiarch replacement, whereas 32 patients (34%) underwent ascending aorta and total arch replacement. Isolated arch replacement was rare. Additionally, 27% of patients underwent aortic valve replacement and 26% underwent root replacement. In-hospital mortality was 7%. Permanent neurological deficits occurred in 5%, transient neurological deficits occurred in 2%. Median SACP time was 24min. Univariate analysis revealed femoral cannulation site (OR: 3.4; CI: 1.25-9.22, P=0.016) as well as HCA ≥40min (OR: 4.21; CI: 1.83-12.58, P=0.001) as predictors of serious adverse events (mortality, neurological injury). CONCLUSIONS Summarizing, elective aortic arch surgery in elderly patients using SACP and moderate HCA provides excellent results regarding mortality and postoperative neurological outcome. Prolonged HCA time and femoral cannulation were the only predictors of serious adverse events (mortality, neurological injury

Field emission from two-dimensional GeAs

GeAs is a layered material of the IV-V groups that is attracting growing attention for possible applications in electronic and optoelectronic devices. In this study, exfoliated multilayer GeAs nanoflakes are structurally characterized and used as the channel of back-gate field-effect transistors. It is shown that their gate-modulated p-type conduction is decreased by exposure to light or electron beam. Moreover, the observation of a field emission current demonstrates the suitability of GeAs nanoflakes as cold cathodes for electron emission and opens up new perspective applications of two-dimensional GeAs in vacuum electronics. Field emission occurs with a turn-on field of ~80 V/{\mu}m and attains a current density higher than 10 A/cm^2, following the general Fowler-Nordheim model with high reproducibility.Comment: 10 pages, 3 figure

Characterization of the electric transport properties of black phosphorous back-gated field-effect transistors

We use thin layers of exfoliated black phosphorus to realize back-gated field-effect transistors in which the Si/SiO2 substrate is exploited as gate electrode. To prevent the detrimental effect of the air exposure the devices are protected by Poly(methyl methacrylate). We report the observation of an improved contact resistance at the interface between the layered material and the metal contact by electrical conditioning. We also demonstrate the existence of a hysteresis in the transfer characteristics that improves by increasing the gate voltage sweep range. Finally, we prove the suitability of such transistors as memory devices

Aflibercept Plus FOLFIRI in the Real-life Setting: Safety and Quality of Life Data From the Italian Patient Cohort of the Aflibercept Safety and Quality-of-Life Program Study

Abstract Background Aflibercept combined with FOLFIRI (folinic acid, 5-fluorouracil, irinotecan) as second-line treatment of metastatic colorectal cancer (mCRC) significantly improved survival compared with FOLFIRI alone in the pivotal VELOUR (aflibercept vs. placebo in combination with irinotecan and 5-fluorouracil in the treatment of patients with metastatic colorectal cancer after failure of an oxaliplatin-based regimen) trial. No quality-of-life assessment was performed in VELOUR; therefore, the ASQoP (Aflibercept Safety and Quality-of-Life Program) trial was designed to capture the safety and health-related quality of life (HRQL). Patients and Methods ASQoP was an international, open-label, single-arm trial evaluating the safety and HRQL of aflibercept combined with FOLFIRI administered in a real-life setting to 781 patients with mCRC, pretreated with an oxaliplatin-based regimen with or without bevacizumab. The Italian subset of ASQoP enrolled 200 patients from 28 institutions. The primary endpoint was safety; HRQL was a secondary endpoint, assessed by validated questionnaires (European quality of life 5-dimension instrument 3-level; European Organization for Research and Treatment for Cancer Quality of Life Questionnaire Core 30, version 3; and EORTC-CR29) at baseline, during treatment, and at the end of treatment. Results The median age of the Italian ASQoP population was 63 years; the median number of aflibercept and FOLFIRI cycles was 7. Treatment-emergent adverse events were reported in 97.5% of patients. Hypertension (28.5%), neutropenia (27.5%; from laboratory data), asthenic conditions (20.0%), diarrhea (17.0%), and stomatitis (13.0%) were the most frequent (incidence, ≥ 5%) grade 3/4 toxicities. One toxic death occurred during the study period due to sepsis, without neutropenic complications. No significant worsening of HRQL was shown during treatment. Conclusion Aflibercept combined with FOLFIRI was well tolerated when administered as second-line treatment for patients with mCRC in a real-life setting. It did not affect HRQL and showed similar rates of treatment-emergent adverse events as those observed in the VELOUR trial. No new safety signals were identified

Dasatinib-Blinatumomab for Ph-Positive Acute Lymphoblastic Leukemia in Adults

BACKGROUND: Outcomes in patients with Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL) have improved with the use of tyrosine kinase inhibitors. Molecular remission is a primary goal of treatment.METHODS: We conducted a phase 2 single-group trial of first-line therapy in adults with newly diagnosed Ph-positive ALL (with no upper age limit). Dasatinib plus glucocorticoids were administered, followed by two cycles of blinatumomab. The primary end point was a sustained molecular response in the bone marrow after this treatment.RESULTS: Of the 63 patients (median age, 54 years; range, 24 to 82) who were enrolled, a complete remission was observed in 98%. At the end of dasatinib induction therapy (day 85), 29% of the patients had a molecular response, and this percentage increased to 60% after two cycles of blinatumomab; the percentage of patients with a molecular response increased further after additional blinatumomab cycles. At a median follow-up of 18 months, overall survival was 95% and disease-free survival was 88%; disease-free survival was lower among patients who had an IKZF1 deletion plus additional genetic aberrations (CDKN2A or CDKN2B, PAX5, or both [i.e., IKZF1 plus]). ABL1 mutations were detected in 6 patients who had increased minimal residual disease during induction therapy, and all these mutations were cleared by blinatumomab. Six relapses occurred. Overall, 21 adverse events of grade 3 or higher were recorded. A total of 24 patients received a stem-cell allograft, and 1 death was related to transplantation (4%).CONCLUSIONS: A chemotherapy-free induction and consolidation first-line treatment with dasatinib and blinatumomab that was based on a targeted and immunotherapeutic strategy was associated with high incidences of molecular response and survival and few toxic effects of grade 3 or higher in adults with Ph-positive ALL. (Funded by Associazione Italiana per la Ricerca sul Cancro and others; GIMEMA LAL2116 D-ALBA EudraCT number, 2016-001083-11; ClinicalTrials.gov number, NCT02744768.)

The ARCH Projects: design and rationale (IAASSG 001)

OBJECTIVE A number of factors limit the effectiveness of current aortic arch studies in assessing optimal neuroprotection strategies, including insufficient patient numbers, heterogenous definitions of clinical variables, multiple technical strategies, inadequate reporting of surgical outcomes and a lack of collaborative effort. We have formed an international coalition of centres to provide more robust investigations into this topic. METHODS High-volume aortic arch centres were identified from the literature and contacted for recruitment. A Research Steering Committee of expert arch surgeons was convened to oversee the direction of the research. RESULTS The International Aortic Arch Surgery Study Group has been formed by 41 arch surgeons from 10 countries to better evaluate patient outcomes after aortic arch surgery. Several projects, including the establishment of a multi-institutional retrospective database, randomized controlled trials and a prospectively collected database, are currently underway. CONCLUSIONS Such a collaborative effort will herald a turning point in the surgical management of aortic arch pathologies and will provide better powered analyses to assess the impact of varying surgical techniques on mortality and morbidity, identify predictors for neurological and operative risk, formulate and validate risk predictor models and review long-term survival outcomes and quality-of-life after arch surger