Recent advances for sustainable and safe marine engines operation with alternative fuels

Pursuing net-zero emissions operations of the shipping industry are quintessential for mitigating this sector the environmental impact caused by the hydrocarbon fuels combustion. Significant contributions are expected from the substitution of the conventional marine fuels by alternative, emissions-free ones with lower emissions footprint. This study aim is to conduct a comprehensive literature review for delineating the main characteristics of the alternative considered fuels, focusing specifically on hydrogen, methanol and ammonia, which recently attracted attention by both the industry and academia. This study comparatively assesses the potential for using these fuels in marine engines and their subsequent performance characteristics, as well as the associated environmental benefits. In addition, the required storage conditions and space as well as the associated costs are reviewed. Special attention is given to the safety characteristics and requirements for each alternative fuel. This study results demonstrate that the environmental benefits from the alternative fuels use are pronounced only when renewable energy is considerably exploited for their production, whereas each fuel feasibility depends on the vessel type and the pertinent storage constraints. Hydrogen, ammonia and methanol, are considered best fit solution to small scale shipping that require minimal on-board storage. In addition, the need for comparative assessments between diesel and alternative fuels is highlighted to shed light on the marine engines operational characteristics. Moreover, jointly using alternative and diesel fuels is identified as a direction towards the transition of the maritime sector decarbonisation, which intensifies the need for optimisation studies of marine engines design and operation. This study concludes with recommendations for future research directions, thus contributing to fuel research concepts for facilitating the shipboard use of alternative fuels

Accurate and reproducible reconstruction of coronary arteries and endothelial shear stress calculation using 3D OCT: Comparative study to 3D IVUS and 3D QCA

Background: Geometrically-correct 3D OCT is a new imaging modality with the potential to investigate the association of local hemodynamic microenvironment with OCT-derived high-risk features. We aimed to describe the methodology of 3D OCT and investigate the accuracy, inter- and intra-observer agreement of 3D OCT in reconstructing coronary arteries and calculating ESS, using 3D IVUS and 3D QCA as references. Methods-Results: 35 coronary artery segments derived from 30 patients were reconstructed in 3D space using 3D OCT. 3D OCT was validated against 3D IVUS and 3D QCA. The agreement in artery reconstruction among 3D OCT, 3D IVUS and 3D QCA was assessed in 3-mm-long subsegments using lumen morphometry and ESS parameters. The inter- and intra-observer agreement of 3D OCT, 3D IVUS and 3D QCA were assessed in a representative sample of 61 subsegments (n ¼ 5 arteries). The data processing times for each reconstruction methodology were also calculated. There was a very high agreement between 3D OCT vs. 3D IVUS and 3D OCT vs. 3D QCA in terms of total reconstructed artery length and volume, as well as in terms of segmental morphometric and ESS metrics with mean differences close to zero and narrow limits of agreement (BlandeAltman analysis). 3D OCT exhibited excellent inter- and intra-observer agreement. The analysis time with 3D OCT was significantly lower compared to 3D IVUS. Conclusions: Geometrically-correct 3D OCT is a feasible, accurate and reproducible 3D reconstruction technique that can perform reliable ESS calculations in coronary arteries

Ship power plants decarbonisation using hybrid systems and ammonia fuel – a techno-economic-environmental analysis

The shipping sector decarbonisation has attracted great attention due to the sector contribution to the worldwide carbon emissions. This study aims at investigating the tech-no-economic-environmental performance of different ship power plants to identify sustainable solutions for a case study cargo ship. Four scenarios, considering conventional and hybrid power plants, the latter with installed batteries, both using marine gas oil and ammonia fuels, are ana-lysed to estimate the pertinent lifetime key performance indicators characterising their economic and environmental performance. Additionally, taxation schemes of varying extent are consid-ered, whereas a sensitivity analysis is carried out to the most uncertain input parameters, namely fuel prices and capital cost. This study results demonstrate that the hybrid plant using ammonia exhibits the lowest environmental footprint associated with 66% carbon emissions reduction, whilst increasing the lifetime cost by 40%. Taxation schemes close to €340 per CO2 tonne are re-quired to render it economically viable whilst meeting the IMO targets for 2050 on CO2 emissions reduction. The sensitivity analysis revealed that the economic output is highly sensitive on the fuels price and the components capital expenditure

Long-term risk, clinical management, and healthcare resource utilization of stable patients with coronary artery disease and post-myocardial infarction in Greece - TIGREECE study

Background: In light of the scarcity of evidence, TIGREECE evaluated the clinical management and long-term outcomes of patients at high risk for an atherothrombotic event who have suffered a myocardial infarction (MI), managed by cardiologists/internists in routine hospital and private office settings in Greece. Methods: TIGREECE, a multicenter, 3-year prospective cohort study, enrolled patients ≥50 years old, with a history of MI 1–3 years before enrollment and with at least one of the following risk factors: age ≥65 years, diabetes mellitus requiring medication, second prior MI, multivessel coronary artery disease, and creatinine clearance 15–60 mL/min. The primary outcome was a composite of MI, unstable angina with urgent revascularization, stroke, or all-cause death. Results: Between 5 June 2014 and 25 July 2015, 305 eligible consented patients (median age: 67.3 years; 81.3% males; 14.8% active smokers; 80.7% overweight/obese) were enrolled; 52.5% had ≥2 qualifying risk factors. The median time from the index MI [ST-segment elevation myocardial infarction (STEMI) in 51.1%, non-STEMI in 33.1%] to enrollment was 1.7 years. Of the patients, 65.9% had been discharged on dual antiplatelet therapy. At enrollment, 94.4% were receiving antiplatelets: 60.0% single [acetylsalicylic acid (ASA): 43.3%; clopidogrel: 15.7%] and 34.4% dual (ASA + clopidogrel: 31.8%) therapy. The Kaplan–Meier estimated 3-year primary composite event rate was 9.3% [95% confidence interval (CI): 6.4–13.0), and the ischemic composite event rate was 6.7% (95% CI: 4.2–9.9). Conclusions: Study results indicate that in the routine care of Greece one in ten patients experience a recurring cardiovascular event or death, mainly of ischemic origin, 1–3 years post-MI