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A brittle failure evaluation of a semi-elliptical surface crack in a pipe mock-up using three variations of the advanced master curve assessment accounting for ductile crack growth, constraint loss and crack front length
No full textRecently, an experiment on a ferritic pipe mock-up, with a semi-elliptical surface crack, loaded in four-point bending, failed by brittle fracture following ductile crack growth. The experiment serves as a case-study to validate advanced methods for assessing brittle failure affected by constraint-loss, ductile crack growth and the crack front length. Previous work has focused on the determination of the component J-R curve. In this work, three variations of the advanced Master Curve assessment are conceptualized and applied to evaluate the probability of brittle failure of the pipe. The sensitivity of the brittle failure prediction to the three variations of the advanced method is investigated by gradually increasing the complexity of the assessment and by varying the input parameters related to constraint, ductility and the crack front length. The J-integral and constraint along the crack front are evaluated using finite element modelling. The results demonstrate the significance of the component J-R curve in the assessment and provide insight into how the input parameters and the assessment method affect the brittle failure prediction. The work contributes to the efficient operation of pressurized components and affects standards development
Solvent-Free Hydrogenation and Dehydrogenation of Quinoline and Quinaldine for the LOHC Concept
No full textAs presented herein, N-heterocyclic quinoline (Q) and quinaldine (MeQ) represent promising liquid organic hydrogen carriers (LOHCs). They can be quantitatively hydrogenated to tetrahydro (TH) forms under mild reaction conditions (100 °C and 10 bar of H2) using Pt/C and Pd/C catalysts. It is noteworthy that the hydrogenation occurs without a solvent, yielding hydrogen storage capacities of up to 2.9 wt·%. Further hydrogenation of Q and MeQ to their decahydro (DH) forms requires the presence of a solvent. In addition to the hydrogenation of Q and MeQ, we succeeded in the dehydrogenation of the TH forms under solvent-free reaction conditions. This suggests that a pressure-controlled system with a single catalyst for hydrogenation and dehydrogenation of the MeQ/Q system could enable hydrogen storage under solvent-free reaction conditions. We also examined various substituted pyridine structures to comprehend the role of protective alkyl groups in hydrogenation. However, solvent-free quinaldine hydrogenation reactions are sensitive to steric changes surrounding pyridine nitrogen. Among the structural variations studied, MeQ with one methyl group has proven to be the most favorable
Durable copper nanowires for flexible curvature sensors
No full textMetal nanowire-based flexible conducting surfaces (FCS) are vital for next-generation flexible and wearable sensors. Copper nanowires (CuNWs) offer a low-cost alternative to the expensive silver nanowires for fabricating FCS, yet their poor stability remains a significant challenge. In this study, we report the synthesis of ultralong CuNWs using a hydrothermal polyol method across a range of temperatures (120–180 ◦C). The CuNWs synthesised at 160 ◦C (CuNW-160) demonstrated the best performance. CuNW-160 films maintained stable conductivity for over 60 days in ambient conditions and thermal stability up to 140 ◦C. A capacitive curvature sensor was fabricated using FCS made with CuNW-160, which maintained consistent performance over 10,000 bending cycles and still showed good curvature sensitivity after 75 days. This highlights the potential use of the copper nanowires by tuning reaction temperature for use in reliable, low-cost flexible electronics
The European bioeconomy strategy revision:An opportunity to go against the tide and secure a sustainable future
No full textIn today's tense geopolitical landscape, marked by strained relations among major powers and deep-rooted dependence on fossil-based economies, the emerging modern bioeconomy can provide resource independence and resilience, in tandem with economic, social, and environmental benefits, and thus has the potential to underpin a sustainable future. The bioeconomy is a vital cross-cutting meta-sector, but it is not inherently circular or sustainable; without intentional design, it risks becoming a linear, unsustainable replacement of the fossil-based economy. Realising its full promise requires purposeful engineering to address climate change, biodiversity loss, strengthen resource independence, support food security and resilience, create jobs, promote social inclusion, boost competitiveness and autonomy, and improve human, animal, and environmental health. The potential is enormous, but so are the challenges society faces in realising the vision for a biobased, nature-positive future.</p
