ABSTRACT
According to Quality-Adjusted Life Expectancy, novel oral anticoagulant therapy is preferred when the stroke risk is higher than 0.9% per year. CHA2DS2-VASc is a tool to select those patients at high risk for stroke due to atherosclerosis and atrial cardiopathy, who could benefit from anticoagulation even in sinus rhythm. Systematic electronic database searches were conducted using Pubmed and Scopus. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement 2020 was followed. Thirteen studies were included, comprising altogether 19,600,104 patients. Data show that the predictive accuracy for stroke of CHA2DS2-VASc among patients with and without atrial fibrillation (AF) is similar, but the benefit of anticoagulation, considering the 1-year risk of stroke for every CHA2DS2-VASc value, starts from higher cutoffs in patients without AF (around CHA2DS2-VASc 4). Atrial fibrillation should no longer be considered a sine qua non for the prevention of thromboembolism in patients at high risk of stroke due to atherosclerosis and atrial disease, but only an additional risk factor to be included in the predictive model used to select patients for novel oral anticoagulant therapy, regardless of the rhythm. CHA2DS2-VASc-AF may be an option. Additional randomized clinical trials are needed.
ABSTRACT
There is a growing concern for finding alternative solutions to construction materials in order to minimise their environmental impact as well as enhancing their service life. This study investigated the durability of cementitious mortars prepared by replacing fine aggregate (sand) with recycled tyre shreds and crumbs, aiming at providing an alternative outlet to tyre waste disposal. Tyre shreds obtained at different particle sizes, from fibres of 0.5-5.0 mm to crumbs of 0.1-0.85 mm in diameter, were used as fine aggregate replacement at 20% by volume. The strength of the mortar samples, their thermal conductivity and their water absorption rate were tested at the age of 28 days and after 20 freeze/thaw cycles. The results showed that the mortar containing tyre crumbs at lower particle sizes resulted in negligible shrinkage, improved freeze/thaw resistance, a reduced water absorption by up to 52% and an improved thermal resistivity.
ABSTRACT
Shape memory polymer (SMP) products have been developed for application as crack closure devices in concrete. They have been made from PET in the form of both fibres and hollow tubes. Here, manufacturing methods using die-drawing and mandrel-drawing to induce shape memory are reported. The fibre-based devices are incorporated into concrete and, upon triggering, exert shrinkage restraint forces that close cracks in the concrete. The evolution of shrinkage restraint force in the fibres as manufactured was measured as a function of temperature, showing stresses in excess of 35 MPa. Tendons consisting of fibre bundles are incorporated into concreate beams subjected to controlled cracking. When activated, the tendons reduce the crack widths by 80%. The same fibres are used to produce another class of device known as knotted fibres, which have knotted ends that act as anchor points when they incorporated directly into concrete. Upon activation within the cracked concrete, these devices are shown to completely close cracks. The tubes are used to enclose and restrain prestressed Kevlar fibres. When the tubes are triggered, they shrink and release the prestress force in the Kevlar, which is transferred to the surrounding concrete in the form of a compressive force, thereby closing cracks. The Kevlar fibres also provide substantial reinforcement after activation. The devices are shown to be able to partially and fully close cracks that have been opened to 0.3 mm and achieve post-activation flexural strengths comparable to those of conventional reinforced and prestressed structural elements. Finally, a preliminary life cycle assessment study was used to assess the carbon footprint a nominal unit of concrete made with SMPs fibres compared to conventional concrete.
ABSTRACT
This case report describes a third successful attempt to ablate a focal atrial tachycardia originating from the left atrial appendage in a highly symptomatic 49-year-old woman using a combined endocardial-epicardial approach, which could be taken into consideration as a safe and effective alternative method for treating similar arrhythmias originating from complex sites.
ABSTRACT
Self-healing concrete has the potential to optimise traditional design approaches; however, commercial uptake requires the ability to harmonize against standardized frameworks. Within EU SARCOS COST Action, different interlaboratory tests were executed on different self-healing techniques. This paper reports on the evaluation of the effectiveness of proposed experimental methodologies suited for self-healing concrete with expansive mineral additions. Concrete prisms and discs with MgO-based healing agents were produced and precracked. Water absorption and water flow tests were executed over a healing period spanning 6 months to assess the sealing efficiency, and the crack width reduction with time was monitored. High variability was reported for both reference (REF) and healing-addition (ADD) series affecting the reproducibility of cracking. However, within each lab, the crack width creation was repeatable. ADD reported larger crack widths. The latter influenced the observed healing making direct comparisons across labs prone to errors. Water absorption tests highlighted were susceptible to application errors. Concurrently, the potential of water flow tests as a facile method for assessment of healing performance was shown across all labs. Overall, the importance of repeatability and reproducibility of testing methods is highlighted in providing a sound basis for incorporation of self-healing concepts in practical applications.
ABSTRACT
Aquifer contamination with diesel fuel is a worldwide environmental problem, and related available remediation technologies may not be adequately efficient, especially for the simultaneous treatment of both solid and water phases. In this paper, a lab-scale 2.45 GHz microwave (MW) treatment of an artificially diesel-contaminated aquifer was applied to investigate the effects of operating power (160, 350 and 500 W) and time on temperature profiles and contaminant removal from both solid and water phases. Results suggest that in diesel-contaminated aquifer MW remediation, power significantly influences the final reachable temperature and, consequently, contaminant removal kinetics. A maximum temperature of about 120 °C was reached at 500 W. Observed temperature values depended on the simultaneous irradiation of both aquifer grains and groundwater. In this case, solid phase heating is limited by the maximum temperature that interstitial water can reach before evaporation. A minimal residual diesel concentration of about 100 mg kg(-1) or 100 mg L(-1) was achieved by applying a power of 500 W for a time of 60 min for the solid or water phase, respectively. Measured residual TPH fractions showed that MW heating resulted in preferential effects of the removal of different TPH molecular weight fractions and that the evaporation-stripping phenomena plays a major role in final contaminant removal processes. The power low kinetic equation shows an excellent fit (r(2) > 0.993) with the solid phase residual concentration observed for all the powers investigated. A maximum diesel removal of 88 or 80% was observed for the MW treatment of the solid or water phase, respectively, highlighting the possibility to successfully and simultaneously remediate both the aquifer phases. Consequently, MW, compared to other biological or chemical-physical treatments, appears to be a better choice for the fast remediation of diesel-contaminated aquifers.