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Forensic investigation of failure in a full-scale composite tidal turbine blade
Get PDFTidal turbine blades endure uniquely harsh, shear-dominated loads that distinguish them from wind turbines, yet their failure mechanisms remain poorly understood. In this study, we report the first full-scale failure investigation of a tidal blade made of glass fibre reinforced polymer (GFRP), carbon fibre reinforced polymer (CFRP) and cast iron. The blade was subjected to 26 static tests and 17 fatigue tests using a bespoke laboratory setup with three hydraulic actuators and saddle fixtures. Strain gauges, displacement transducers, and digital image correlation (DIC) were coupled to track local deformation and damage. Artificial defects accelerated damage progression, yielding roughly 97,000 fatigue cycles before ultimate failure. Two dominant failure modes emerged: de-bonding between the pressure skin and root connection under quasi-static loading at 216 % of design load, and bondline failure between pressure and suction skins under fatigue at 119 % of design load. A subsequent static test showed residual strength drop to only 68.8 % of the original design load. These findings highlight the critical role of bond interfaces in blade integrity and the contribution of internal ribs in maintaining structural performance. While local stiffness was affected by damage, global stiffness remained largely intact, reinforcing the importance of investigating long-term performance degradation and failure evolution in tidal turbine blades
APEX: Automated Protein EXpression in Escherichia coli
Get PDFHeterologous protein expression is an indispensable strategy for generating recombinant proteins. Escherichia coli (E. coli) is the most widely used microbial host for recombinant protein production due to its rapid growth, well-characterized genetics, and ability to produce recombinant proteins in high yields using modern recombinant DNA technology. However, while there is a plethora of robust protein expression protocols for E. coli, these methods are often unsuitable for high-throughput screening due to their significant resource and time consumption; these protocols are also susceptible to operator error and inconsistency. To address these challenges, we developed Automated Protein EXpression (APEX), a robust and automated pipeline for recombinant protein production in E. coli. APEX leverages the accessible, open-source Opentrons OT-2 platform to automate microbial handling and protein expression with high precision and reproducibility. APEX can be configured to perform heat shock transformation, selective plating, colony sampling, microculturing, and protein expression induction using a low-cost, minimal OT-2 hardware setup. We further demonstrate the efficacy of our automated transformation workflows using a variety of plasmids (2.7–17.7 kb) and exemplify the automated heterologous expression of a diverse array of proteins (27–222 kDa). Designed with customization, modularity, and user-friendliness in mind, APEX can be easily adapted to the operator’s needs without requiring any coding expertise. APEX is available at https://github.com/stracquadaniolab/apex-nf under the AGPL3 license
Engineering Protein–Peptide Interfaces via Combinatorial Mutagenesis and Mass Photometric Screening:Biomolecules
Get PDFThe SpyTag–SpyCatcher system, developed by the Howarth lab, is based on splitting the CnaB2 domain from Streptococcus pyogenes into two parts: a 13-amino-acid SpyTag and a 116-amino-acid SpyCatcher. Upon incubation, they spontaneously form a covalent isopeptide bond between Asp7 (SpyTag) and Lys31 (SpyCatcher). This study explores whether the interaction specificity can be modulated by altering hydrophobic residues within the SpyCatcher binding pocket and corresponding SpyTag positions, potentially to create orthogonal SpyTag–SpyCatcher pairs. Libraries of SpyCatcher and SpyTag were created by partial saturation mutagenesis using overlap PCR and MAX randomisation, respectively. To assess the specificity of the SpyCatcher–SpyTag interaction within the resulting protein mixtures, a novel screening strategy based on mass photometry was developed to detect isopeptide bond formation. We demonstrate tolerance to mutation in the hydrophobic binding pocket of SpyCatcher in terms of binding native SpyTag and demonstrate what to our knowledge constitutes the first example of using mass photometry to examine the interactions of small libraries of proteins with a given ligand. Mass photometry detects stable interactions whether covalent or not and so this study suggests the prospect of employing mass photometry for more general application in protein engineering
Simulation of Multi-Physicochemical Methane Photocatalytic Process in the SCPP-HPCR Using Lattice Boltzmann Method
Get PDFConstructed by a solar chimney power plant (SCPP) and a honeycomb photocatalytic reactor (HPCR), the system can remove non-CO2 greenhouse gases on a large scale. A mesoscopic-scale fluid flow heat transfer model of the photocatalytic reaction region within the SCPP-HPCR system has been established based on the Lattice Boltzmann method (LBM). Multiple distribution functions have been introduced to simulate the distribution of flow, temperature, and concentration of the photocatalytic region. The performance of photocatalytic methane in the SCPP-HPCR system has been analyzed under the influence of different operating and structural parameters. The results show that increasing the inlet methane flow rate can improve the efficiency of photocatalytic and purification rate of CH4, and lead to the increase in carbon dioxide generation rate. When the solar radiation Gr=857 W/m2 and the inlet flow rate Qp=750 mL/min, the photocatalytic efficiency can reach 30.67%. Furthermore, decreasing the aperture size results in enhanced photocatalytic efficiency, purification rate of CH4, and equivalent CO2 reduction rate. When the inlet flow rate Qp=1000 mL/min and the aperture size Dp=0.5 mm, the photocatalytic efficiency can reach 40.23%. Conversely, an increase in the temperature leads to a slight decrease in all evaluated criteria, and the highest photocatalytic efficiency is 24.79% at a temperature of 298 K. These findings provide valuable insights and guidance for subsequent simulation studies on a more microscopic scale.</p
Capacitated Facility Location Problem under Uncertainty with Service Level Constraints
Get PDFClassic facility location models often assume customer demands to be deterministic, although real-world demand is usually uncertain, especially in long-term strategic planning. While stochastic programming models are widely used to address uncertainty, the default approach of ensuring that the facility capacities are met at all times, i.e., for every scenario, can sometimes produce overly conservative solutions. This paper presents a novel stochastic programming model that incorporates a range of service level restrictions that allow demand to be unsatisfied with a certain probability and up to a certain amount. Concerning the former, we use two α-service level constraints, a well-known local and a new global constraint, while the latter is controlled through two β-service level constraints that take the expected value and the maximum value of the excess demand into account. The service levels are incorporated in the stochastic programming model using chance constraints. To solve the model’s deterministic equivalent, we implement a Benders’ decomposition and a modified sample average approximation algorithm with concentration sets. We carry out experiments on randomly generated data sets and a real-world inspired case study in Scotland to compare the performance of models with different service level combinations, as well as with the classical penalty model
Materials Engineering for High Performance and Durability Proton Exchange Membrane Water Electrolyzers
Get PDFProton exchange membrane water electrolyzers (PEMWEs) are expected to play a crucial role in the global green energy transition during the 21st century. They provide a versatile and sustainable solution for generating hydrogen with very high purity in combination with renewable energies, such as solar and wind. Despite their promise, PEMWEs face several critical problems, including high costs, performance limitations, and durability challenges, particularly at low iridium (Ir) loading on the anode. Advancing next-generation PEMWEs requires extensive work on materials engineering of all cell components, including the catalyst layer (CL), membrane, porous transport layer (PTL), bipolar plate (BPP), and gasket. This task must be performed with the complementary contribution of different modeling and characterization techniques. This review presents a critical perspective from academia, research centers, and industry, mapping main developments, remaining gaps, and strategic pathways to advance PEMWE technology. A focus is devoted to key aspects, such as operation at low Ir loading, membrane durability, multiscale transport layers, porous and non-porous flow fields, multiphysics modeling, and multipurpose characterization techniques, which are thoroughly discussed. By unifying these topics, this review provides readers with the essential knowledge to grasp current developments and tackle tomorrow’s challenges in PEMWE engineering
Characterizing the food environment in Scotland and its association with deprivation: A national study
Get PDFObjectives: To characterize food outlets across Scotland and analyze their distribution by neighborhood deprivation.Methods: Data from the Food Standards Agency of all registered food businesses in 2024 were categorized as out-of-home (OOH) [including restaurants, pubs, cafés, and takeaways], retail [supermarkets and non-food retailers like pharmacies with limited food items] or other [mobile caterers, charity organizations, and home caterers]. Neighborhood deprivation was quantified using the Scottish Index of Multiple Deprivation.Results: Of all food outlets, 59% (n=18,409) were OOH, 28% (n=8,757) retail, and 13% (n=3,969) other. The density of OOH (1.9 per km2) was more than double that of retail (0.8 per km2 11 ). Glasgow City had the highest OOH outlet density (18.5 per km2 12 ). Argyll and Bute, Western Isles, and Highlands had the lowest density of both OOH and retail (≤0.03 per km2 13 ). Compared to the most deprived neighborhoods, the least deprived neighborhoods had more Restaurants/cafés/canteens (37% versus 23% of food outlets, respectively) and fewer Takeaways/sandwich shops (16% versus 24% of food outlets, respectively).Conclusion: Though OOH outlets far outnumber retail in all of Scotland, unique food environments exist in different local authorities. These insights can inform local development and support targeted strategies to improve food environments
Connectedness in weighted consensus division of graphical cakes between two agents
Get PDFAustin's moving knife procedure was originally introduced to find a consensus division of an interval/circular cake between two agents, each of whom believes that they receive exactly half of the cake. We generalise this in two ways: we consider cakes modelled by graphs, and let the two agents have unequal, arbitrary entitlements. In this setting, we seek a weighted consensus division – one where each agent believes they received exactly the share they are entitled to – which also minimises the number of connected components that each agent receives. First, we review the weighted consensus division of a circular cake, which gives exactly one connected piece to each agent. Next, by judiciously mapping a circle to a graph, we produce a weighted consensus division of a star graph cake that gives at most two connected pieces to each agent — and show that this bound on the number of connected pieces is tight. For a tree, each agent receives at most h+1 connected pieces, where h is the minimal height of the tree. For a connected graphical cake, each agent receives r+2 connected pieces, where r is the radius of the graph. Finally, for a graphical cake with s connected components, the division involves at most s+2r+4 connected pieces, where r is the maximum radius among all connected components.</p
Preserving Centromere Identity: Right Amounts of CENP-A at the Right Place and Time
Get PDFFour decades ago, the discovery of centromere protein-A (CENP-A) marked a pivotal breakthrough in chromosome biology, revealing the epigenetic foundation of centromere identity. CENP-A, a histone H3 variant, directs the formation of the microtubule-binding kinetochore complex, designating the chromosomal site for its assembly and underpins the accurate partitioning of genetic material during cell division. Errors in cell division can give rise to DNA instability and aneuploidy, implicated in human diseases such as cancer. Therefore, discovering the underlying pathways and mechanisms responsible for the formation, regulation and maintenance of the centromere is important to our understanding of genome stability, epigenetic inheritance, and in providing the knowledge to help generate possible treatments and therapeutics. Here, we review various molecular pathways and mechanisms implicated in maintaining centromere identity and highlight some of the key outstanding questions with a focus on the human centromere
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