Fracture toughness of AlSi10Mg alloy produced by direct energy deposition with different crack plane orientations

The fracture and tensile behaviors of the AlSi10Mg alloy processed by Direct Energy Deposition were investigated. Three-point bending fracture toughness and tensile specimens were tested at room temperature along different crack plane orientations and loading directions. Before being machined and tested, the printed samples were subjected to heat treatment at 300 °C for 2 h to relieve the residual stresses. Microstructural and fractographic analyses were performed to investigate the fracture mechanisms and the crack propagation paths for each crack orientation. Significant differences in the fracture toughness were observed among the crack plane orientations. Specimens with cracks oriented in the X-Y direction featured the highest fracture toughness values (JIc = 11.96 kJ/m2), whereas the Z-Y crack orientation (perpendicular to the printing direction) performed the lowest fracture toughness values (JIc = 8.91 kJ/m2). The anisotropy in fracture toughness is mainly related to a preferential crack propagation path along the melt pool boundaries. At melt pool boundaries, pores are preferentially placed, coarsening of the microstructure occurs and there is higher Si content, leading to that area being less ductile and less resistant to crack propagation

Macroloides for the treatment of severe respiratory illness caused by novel H1N1 swine influenza viral strains

Producción CientíficaThe current outburst of a new H1N1 swine influenza strain(s) in México and the United States is causing great concern in health authorities and in the general population [1]. With the World Health Organization (WHO) reporting the pandemic potential of the new strain, it is necessary to determine which therapeutic options are available until a specific vaccine is available. Based on information from the Centre for Disease Control (CDC), the virus is sensitive to oseltamivir and zanamivir. Antivirals are strongly affected by viral mutations; thus their efficiency could be lost as the virus changes

Propensity score matched comparison of transcatheter aortic valve implantation versus conventional surgery in intermediate and low risk aortic stenosis patients: A hint of real-world

Background: Recently, the use of transcatheter aortic valve implantation (TAVI) in inter­mediate-low risk patients has been evaluated in the PARTNER II randomized trial. However, in the last years, this therapy has been employed in this scenario with underreported results, as compared to surgical aortic valve replacement (SAVR). Methods: We enrolled 362 consecutive patients with severe symptomatic aortic stenosis and intermediate-low surgical risk (logEuroSCORE < 20%), treated in our center with TAVI (103 patients) or single SAVR (259 patients) between 2009 and 2014. Patients were matched according to age, gender, logEuroSCORE, and use of bioprosthesis. Results: Mean age of the patients was 73 ± 10.4 years, and 40.3% were women. LogEuroSCORE and Society Thoracic Surgeons score were 7.0 ± 4.4% and 4.2 ± 2.5%, respectively, with mean left ventricular ejection fraction of 52 ± 9%. There were no differences regarding other comorbidities. The length-of-hospitalization was 11 ± 5 days after TAVI vs. 17 ± 9 days after SAVR (p = 0.003). After matched comparison, no differences in terms of in-hospital mortality (5.7% after TAVI vs. 2.9% after SAVR, p = 0.687) and 1-year mortality (11.4% vs. 7.1%, p = 0.381) were found. The combined endpoint of stroke and mortality at 1-year was also similar between both groups (15.7% in TAVI patients vs. 14.4% after SAVR, p = 0.136). Multivariate analysis determined that aortic regurgitation (AR) was an independent predictor of mortality (OR = 3.623, 95% CI: 1.267–10.358, p = 0.016). Although the rate of AR was higher after TAVI, none of the patients treated with the newest generation devices (10.7%) presented more than a mild degree of AR. Conclusions: TAVI is feasible and shows comparable results to surgery in terms of early, 1-year mortality, as well as cerebrovascular events in patients with severe aortic stenosis and intermediate-low operative risk. Better transvalvular gradients, yet higher rates of AR were found, however, newer devices presented comparable rate of AR.

The management of acute venous thromboembolism in clinical practice. Results from the European PREFER in VTE Registry

Venous thromboembolism (VTE) is a significant cause of morbidity and mortality in Europe. Data from real-world registries are necessary, as clinical trials do not represent the full spectrum of VTE patients seen in clinical practice. We aimed to document the epidemiology, management and outcomes of VTE using data from a large, observational database. PREFER in VTE was an international, non-interventional disease registry conducted between January 2013 and July 2015 in primary and secondary care across seven European countries. Consecutive patients with acute VTE were documented and followed up over 12 months. PREFER in VTE included 3,455 patients with a mean age of 60.8 ± 17.0 years. Overall, 53.0 % were male. The majority of patients were assessed in the hospital setting as inpatients or outpatients (78.5 %). The diagnosis was deep-vein thrombosis (DVT) in 59.5 % and pulmonary embolism (PE) in 40.5 %. The most common comorbidities were the various types of cardiovascular disease (excluding hypertension; 45.5 %), hypertension (42.3 %) and dyslipidaemia (21.1 %). Following the index VTE, a large proportion of patients received initial therapy with heparin (73.2 %), almost half received a vitamin K antagonist (48.7 %) and nearly a quarter received a DOAC (24.5 %). Almost a quarter of all presentations were for recurrent VTE, with >80 % of previous episodes having occurred more than 12 months prior to baseline. In conclusion, PREFER in VTE has provided contemporary insights into VTE patients and their real-world management, including their baseline characteristics, risk factors, disease history, symptoms and signs, initial therapy and outcomes

Critical fracture toughness, JC and δ5C, of unidirectional fibre-metal laminates.

Fibre-metal laminates (FMLs) are structural composites designed aiming to produce a damage-tolerant and high strength material. Their main characteristic is their very low fatigue crack propagation rates when compared to traditional aeronautical Al alloys. Their application in aeronautical structures demands a deep knowledge of a wide set of mechanical properties and technological values, including both fracture toughness and residual strength. The objectives of the present work were to present critical toughness values (JC and δ5C) of unidirectional FMLs obtained following a recently proposed methodology and to use them for critical crack length and residual strength predictions. Residual strengths of middle centre-cracked panels of Arall® 2 and 3 were predicted and compared to experimental values from the literature. The results showed that all FMLs evaluated presented higher fracture toughness and crack tolerance than their constituent alloys and that the measured fracture toughness was useful for an accurate prediction of residual strength in centre-cracked plates of Arall