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The accelerated propagation of pulsed gravity currents
No full textPulsed gravity currents are generated by the sequential release of dense material into a lighter ambient. We investigate the dynamics of pulsed gravity currents using physical scale experiments, two-dimensional depth-averaged shallow water equation (SWE) based models and three-dimensional lattice Boltzmann method (LBM) simulations. Integrating these results we show for the first time that short duration pulsed releases generate intrusive layers, which accelerate front propagation relative to an instantaneously released current of the same total volume. Conversely, a long delay time between pulses produces a current that propagates slower than an equivalent instantaneous release. This finding is supported by physical experiments and depth-resolving LBM simulations. The depth-resolving simulations show that intrusions in pulsed flows experience less drag resistance than those generated by instantaneous releases. The depth-averaged model considered in the present study does not accurately capture the intrusive flow dynamics of pulsed currents. However, the limitations of the finite-depth SWE model may be mitigated by extensions to incorporate entrainment and density stratification. The results also motivate further research into the impact of buoyancy Reynolds number and channel slope on the propagation of pulsed currents
Social and emotional cognition in Pleistocene hominin evolution:The role of biocultural processes
No full textPatterns and processes of social cognition underlie much of the behavioral and ecological flexibility and adaptive capacity that characterizes the primate order. The hominin lineage emerged from a branch of primates, hominoids, particularly reliant on the navigation of complex intra and inter-group social relations as a central dynamic of their niche. Over the past few decades much research on hominin evolution has resituated focus from explaining the uniqueness of the big-brain, hyper-social, cognitively distinct Homo sapiens, to a broader inquiry into the potential process, pathways, and dynamics of the evolution of a hominin niche, or niches, rooted in increasingly complex social cognition. In this essay we review key aspects of this current paradigm and argue for the expanded inclusion of the possibilities of socio-emotional cognition in a biocultural approach as advantageous in developing a more robust descriptive framework for theory and method in the study of human evolution. We combine several sources and examples to highlight specific theoretical approaches to assist in developing a common and more integrative framework for investigating social and emotional cognition as a key component of the biocultural niche in Pleistocene hominins
Thermodynamics of stacking faults in GaAs-based system revealed by in-situ heating in TEM
No full textStacking faults (SFs) are a type of two-dimensional defect that can significantly degrade the performance of III-V semiconductor devices. In this study, we investigate the thermal evolution of intrinsic SFs in (In)GaAs-on-Si systems using in-situ heating in an aberration-corrected scanning transmission electron microscopy. Our results indicate that chiral intrinsic SFs near the InGaAs/GaAs interface undergo thermally induced migration and interaction, leading to the formation of Lomer-Cottrell locks at 700 °C. Between 200 and 700 °C, SFs exhibit sliding behaviour, which triggers their reaction into a characteristic three-layer defect (TLD) structure, which could be quickly annihilated during the baking environment. Using Lorentz transmission electron microscopy (LTEM) to image magnetization configurations, we observed the formation of intrinsic stacking fault (SF)-induced magnetic vortices. These vortices arise from the competition between the Heisenberg exchange interaction and the Dzyaloshinskii-Moriya interaction (DMI). Notably, as field-driven dipole oscillations intensify, the magneto-Stark effect enables manipulation of transitions between out-of-plane and in-plane magnetic vector fields. This work advances the understanding of defect dynamics in III-V compound semiconductors and provides new strategies for tailoring crystal quality during epitaxial growth
A causal validation augmented temporal convolutional framework for brain effective connectivity networks estimation
No full textAdvancements in neuroimaging have facilitated unprecedented insights into brain connectivity, making the study of brain effective connectivity networks (ECNs) essential for understanding neurological functions and diseases. Recently, neural networks (NNs) have emerged as powerful tools for ECN estimation due to their prominent universal approximation ability and less reliance on prior knowledge. However, most NN-based approaches fail to eliminate redundant temporal information and lack rigorous causal validation mechanisms. This paper introduces a novel end-to-end framework for estimating ECNs utilising Least Absolute Shrinkage and Selection Operator (Lasso) regression of Temporal Convolutional Networks (TCNs), named the Causal Validation augmented Temporal Convolutional Framework (CVTCF). In the CVTCF, a convolutional Hierarchical Group Lasso (cHGL) is proposed to detect Granger Causality (GC) inputs and eliminate redundant temporal information during GC detection. Additionally, the framework incorporates permutation importance validation based on the Wilcoxon signed-rank test to enhance the reliability of GC detection. The proposed CVTCF generally outperformed state-of-the-art methods in a controlled simulation using the chaotic Lorenz-96 model and the publicly available blood-oxygen-level-dependent (BOLD) benchmark dataset. Furthermore, the proposed CVTCF has enabled a detailed analysis of the causal interactions within the cerebral cortex, bringing to light the intricate relationships that underlie neurological functioning and impairment of neurodegenerative conditions like Alzheimer's Disease (AD) and Parkinson's Disease (PD). This study demonstrates the potential of using ECN estimation based on the CVTCF as indicators for neurodegenerative diseases and paves the way for future diagnostic and therapeutic strategies
Behaviour of heated steel beams with lateral and axial restraint in steel-timber hybrid structures
No full textAmidst the climate emergency and ambitions to decarbonise the built environment, hybrid systems consisting of a steel structural frame supporting cross-laminated timber floors have emerged as a new paradigm in sustainable construction. While this form of hybridisation is beneficial in many ways, it also presents certain challenges, particularly regarding its structural performance in fire. A critical concern in fire is the risk of lateral-torsional buckling of the steel beams connected to the timber slabs with self-tapping screws, which goes beyond the scope of current design guidance. Using a numerical approach, this study has developed finite element modelling capacity to investigate the thermo-mechanical response of a 9 m unprotected steel beam with screws at 250 mm spacing under various levels of lateral restraint from the screws and axial restraint from the end connections. The imposed heating regimes have also explored the influence of the temperature on the compression flanges of the steel beam. When axial restraint is present, indicating a realistic support condition in fire, the beam initially behaves similarly to a corresponding fully laterally restrained beam. This response continues until the first screw fails in the midspan region, which eventually triggers instability by lateral-torsional buckling. The results highlight the significance of lateral restraint in enhancing the fire performance of steel-timber hybrid structures. However, it is not realistic to assume a full lateral restraint condition in fire design
Analysis and quantification of the propensity of hair dyes to desorb from human hair fibre using an accelerated 48-wash method
No full textThe durability of oxidative hair dyes is a critical factor in consumer satisfaction and hair colour product development. This study introduces an accelerated 48-wash analytical method for quantifying hair dye desorption, combining spectrophotometric colour strength measurements with a back-extraction protocol coupled to HPLC. The approach was first validated using a two-component model dye system comprising p-aminophenol and 2-methyl-5-aminophenol, forming a heterodimeric product that could be quantitatively monitored. Hair types studied included Natural White Hair and Bleached Blonde Hair, with dyeing performed using either ammonia or monoethanolamine as the alkalizing agent. Results demonstrate that most colour loss occurs during the first wash, and Bleached Blonde Hair treated with monoethanolamine exhibits the highest dye desorption, reflecting superficial dye deposition and structural vulnerability of chemically processed hair. In contrast, ammonia-based formulations promote deeper dye penetration and improved retention. Colour loss trends quantified by spectrophotometric measurement followed a logarithmic pattern over the accelerated 48 wash test, and strong correlations (R2 > 0.95) were observed between spectrophotometric data and HPLC quantification of dye removal. The robustness of the method was also demonstrated on multi-component dye formulations, and although direct HPLC quantification was challenging for these more complex systems, the spectrophotometric measures serve as a reliable proxy for quantification of actual dye loss, based on the calibration established with the model two-component system. This work provides a quantitative framework for understanding hair dye wash fastness, the influence of hair type and alkaliser, and the mechanisms of dye desorption. The method supports future product innovation by linking molecular-level dye behaviour to long-term colour performance
Tribology of dual Pickering double emulsions: Machine learning-aided inner droplet analysis
No full textThis study investigated the tribological performance of Pickering water-in-oil emulsions and dual Pickering water-in-oil-in-water double emulsions (DEs) stabilized with particles at both the interfaces. W/O emulsions were stabilized by cocoa butter-based oleogel (CBolg) crystals, while DEs incorporating these emulsions were stabilized by whey protein microgels (WPM). The influence of temperature (21 and 37 °C) and surface texture (smooth vs biomimetic tongue-like surface) were investigated in tribology of W/O emulsions (30–60 % v/v water) and DEs (with 20 and 60 wt% W/O phase). In smooth surfaces, CBolg played a critical role in reducing the friction coefficient (μ) primarily via a fat-driven lubrication mechanism that was temperature dependent. While in DEs, smaller oil droplets encapsulating water provided similar lubrication to oil-based systems until starvation occurred. Strikingly, the water content in W/O emulsions exhibited distinct differences between emulsion systems within the biomimetic tongue-like surfaces, demonstrating lower lubricity at higher water concentration. Confocal microscopy images analyzed using Machine Learning (ML)-supported droplet segmentation enabled a more precise evaluation of structural changes within DEs when subjected to tribological stress. We demonstrated that although changes in inner droplet size altered in DEs, their contribution to the overall lubrication performance was minimal, due to their limited entrainment. Of more importance, the tribological performance was governed by the WPM with minimal influence from the droplet-entrained phenomena. These fundamental insights highlight the relevance of structured water in understanding frictional performance in emulsified systems, with structural integrity, composition, and topography of the tribological surface emerging as key factors
From twin transition to twice the burden? Digitalisation, energy demand, and economic growth
No full textThis paper evaluates the potential of digitalisation to drive structural transformations towards a sustainable economy. We apply an index decomposition analysis (IDA) to understand the factors influencing energy demand in a panel of 31 high-income countries (1971–2019). The IDA framework includes four factors related to the scale and sectoral composition of the economy and technical improvements, accounting for the quality of energy flows and actual work potential through useful exergy measures. We apply the model at the sector level across 16 productive industries to explore cross-sector heterogeneity in energy demand, and then compare results across digitial intensity categories. We find that value added growth is the primary driver of energy use. While digitalisation alone does not fully explain trends in energy demand, it is strongly associated with value added growth in high digital intensity sectors and amplifies the use of energy. Left ungoverned, digitalisation risks intensifying economic–ecological tensions, but if steered towards socio-ecological priorities—while addressing the environmental costs of growth—it holds potential to deliver real benefits. We discuss these findings in the context of recent policy actions promoting the “twin” green and digital transition
Synergistic piezophototronic and plasmonic effects in Pt-Pd/BiVO4 composites for enhanced tetracycline degradation
No full textPiezo-photocatalysis has emerged as a promising strategy for environmental remediation, particularly in addressing persistent organic pollutants such as antibiotics. However, its practical implementation faces two critical challenges: (1) rapid recombination of photogenerated electron-hole pairs and (2) insufficient active sites for surface redox reactions. To overcome these limitations, we developed an innovative piezo-photocatalytic system composed of ultrathin BiVO4 nanosheets decorated with bimetallic Pt-Pd alloy nanoparticles (Pt-Pd/BiVO4) for efficient tetracycline (TC) degradation. As an efficient combination of photocatalysis and piezocatalysis, the built-in polarization field generated by the piezoelectric effect of BiVO4 catalysts could serve as a powerful driving force for the separation and migration of photoexcited charges. Simultaneously, the Pt-Pd nanoparticles enhance catalytic performance through (i) localized surface plasmon resonance (LSPR)-induced hot electron generation and (ii) optimized charge transfer pathways due to their superior electrical conductivity. Under simultaneous ultrasonic vibration and visible light illumination, the PPB-0.5 composites achieves an outstanding TC degradation rate constant (k = 0.071 min−1), representing a 3.54-fold enhancement compared to pure BiVO4. Furthermore, the degradation efficiency remains nearly 90 % after four cycles, highlighting the system's stability. The result reveal that the synergistic coupling of photocatalysis, piezoelectric polarization and plasmonic excitation significantly promotes the generation of reactive oxygen species (ROS), particularly ·OH and ·O2- radicals, which play a dominant role in TC degradation. This work not only provides fundamental insights into piezo-photo-plasmonic coupling effects but also offers a viable design strategy for developing robust hybrid catalysts for wastewater treatment applications
PIEZO1 channel mechanosensing in hepatobiliary physiology and disease
No full textThe hepatobiliary system is constantly exposed to dynamic mechanical forces, including fluid shear stress, bile canaliculi pressure, and extracellular matrix stiffness. While traditionally studied for its metabolic and detoxifying functions, it is now increasingly recognised as a mechanosensitive organ. This review focuses on PIEZO1 mechanically gated ion channels that transduce physical cues into calcium-dependent signalling events. PIEZO2, the only other PIEZO isoform, is not known to be relevant in the hepatobiliary system. We examine the current knowledge on PIEZO1 in liver physiology, highlighting its roles in liver sinusoidal endothelial cells, hepatocytes, and macrophages. In health, PIEZO1 regulates key processes such as bile acid synthesis (via nitric oxide–mediated suppression of CYP7A1), bile flow, antioxidant defence, and iron homeostasis. In disease, PIEZO1 activity is linked to pathological processes such as inflammation, fibrosis and angiogenesis in the context of cirrhosis and hepatocellular carcinoma. We discuss the idea that the liver alternates between two functional states depending on portal vein flow: a high-flow state favouring detoxification and metabolism, and a low-flow state that prioritises bile acid production. Understanding how PIEZO1 contributes to these transitions offers new insights into liver’s ability to adapt its function and metabolism. Further research on hepatobiliary PIEZO1 will advance the understanding of how physical exercise promotes health and opens new opportunities for enhancing liver regeneration after surgical resection and liver function in chronic diseases such as fibrosis and cirrhosis