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Benchmarking selective capture of trace CO2 from C2H2 using an amine-functionalized adsorbent
No full textPurifying C2H2 by removing trace CO2 is critically needed yet challenged by their analogous physical properties. Herein, we report a commercial resin adsorbent HP20 (Diaion® HP-20 Resin) loaded with polyethyleneimine (PEI@HP20) which selectively captures trace CO2 and excludes C2H2. PEI@HP20 possesses a high CO2 adsorption capacity (4.35 mmol/g) at 100 kPa and 298 K and a record CO2/C2H2 uptake ratio compared with all reported CO2-selective adsorbents. The ideal adsorbed solution theory selectivity reaches 1.33×107 . The pilot-scale pressure-temperature swing adsorption on 2 kg PEI@HP20 further validated that it can obtain >99.99% purity C2H2 from CO2/C2H2(1/99, v/v) mixtures with a high yield of 344.7 g per cycle. The combination of multinuclear solid-state Nuclear Magnetic Resonance, Fourier Transform infrared spectroscopy and density functional theory calculations reveal that the performance of PEI@HP20 relies on a dual chemisorption/ physisorption mechanism. This work highlights a promising method to develop green, low cost, high efficiency, and readily scalable CO2-selective adsorbent.</p
The edges of glaciology
No full textAn IGS international symposium on ‘The edges of glaciology’ was held in the University of Limerick from 2 to 7 July 2023, and this article is the preface to the resulting issue of the Annals of Glaciology. The edges of glaciology are most obviously those parts of the study of ice and ice masses which involve boundaries: grain boundaries, ice cores, the glacier bed, the glacier surface, shear margins, crevasses and calving, but these and other subjects also sometimes involve philosophical edges, where different presumptions and practices can lead to controversy: for example, theories of drumlin formation or till deformation. And yet again, there are territorial edges, where glaciology lies at the interface with other disciplines, as for example in ice shelf–ocean interactions, rheology of granular materials, firn sintering and compaction. The aim of the conference was to explore and encourage discussion of all such edges. In keeping with this theme, the present preface also treads the edges of acceptability.</p
Do publicly funded community physical activity programs for middle‑aged and older adults in Ireland work?
No full textTo strengthen practice-based evidence, pragmatic, yet rigorous, evaluation of real-world programs is necessary. This study sought to add to the evidence for the effectiveness of physical activity programs for middle-aged and older adults offered by publicly funded local sports partnerships (LSPs) in Ireland. We analysed data from 468 individuals aged 50+years, who took part in the Move for Life cluster randomised feasibility trial. Outcomes were accelerometer-based moderate-to-vigorous intensity physical activity (MVPA), light intensity physical activity (LiPA), standing time, and sedentary time; self-reported compliance with physical activity guidelines, body composition, physical function, and mental well-being. LSP programs included Women on Wheels/Bike for Life, Go for Life Games, Get Ireland Walking, and Men on the Move. We used a diference-in-diferences approach to estimate program effects. We found evidence of positive program effects on accelerometer-derived MVPA (Women on Wheels/Bike for Life, Get Ireland Walking), LiPA (Go for Life Games), and sedentary time (Women on Wheels/Bike for Life, Go for Life Games) (p<.05), plus evidence of positive effects on self-reported physical activity for all LSP programs (p<.05). We did not find evidence of program effects on body composition. Outcomes related to physical function were mixed. Men on the Move was the only program where mental well-being scores increased significantly relative to the control group. Despite sample size limitations, the results support the effectiveness of LSP programs over a 6-month period, notably in terms of energy expenditure outcomes, while identifying areas for improvement regarding outcomes related to body composition, physical function and, particularly, mental well-being</p
Predictive modeling for driver insurance premium calculation using advanced driver assistance systems and contextual information
No full textTelematics devices have transformed driver risk assessment, allowing insurers to tailor premiums based on detailed evaluations of driving habits. However, integrating Advanced Driver Assistance Systems (ADAS) and contextualized geolocation data for predictive improvements remains underexplored due to the recent emergence of these technologies. This article introduces a novel risk assessment methodology that periodically computes weekly insurance premiums by incorporating ADAS risk indicators and contextualized geolocation data. Using a naturalistic dataset from a fleet of 354 commercial drivers over a year, we modeled the relationship between past claims and driving data, and use that to compute weekly premiums that penalize risky driving situations. Risk predictions are modeled through claims frequency using Poisson regression and claims occurrence probability using machine learning models, including XGBoost and TabNet, and interpreted with SHAP. The dataset is divided into weekly profiles containing aggregated driving behavior, ADAS events, and contextual attributes. Results indicate that both modeling approaches show consistent attribute impacts on driver risk. For claims occurrence probability, XGBoost achieved the lowest Log Loss, reducing it from 0.59 to 0.51 with the inclusion of all attributes; for claims frequency, no statistically significant differences were observed when including all attributes. However, adding ADAS and contextual attributes allows for a comprehensive and disaggregated interpretation of the resulting weekly premium. This dynamic pricing can be incorporated into the insurance lifecycle, enabling bespoke risk assessment based on emerging technologies, the driving context, and driver behavior.</p
Interpretability and the nature of latent representations in deep neural networks
No full textInterpreting the inner workings of deep neural networks is crucial for establishing trust and ensuring model fairness and safety. Mechanistic interpretability aims to understand how models store representations by breaking down neural networks into interpretable units. In contrast, concept-based interpretability is concerned with high-level human interpretable concepts such as textures, shapes, and parts of objects present as directions in the latent space of a model, meaning the lower-dimensional, abstract representation of data within hidden or “latent” layers of a model.In this manuscript, we study interpretability and the nature of representations in neural networks, concentrating mainly on the context of computer vision. We explore some limitations of mechanistic and concept-based interpretability methods that make interpreting individual neurons and directions challenging. In order to address such challenges, we develop methods to locate distinct human interpretable concepts and we study how such concepts relate to each other in the activation space. Furthermore, we take a step towards understanding model representations in a way that goes beyond simply locating concepts for mechanistic analyses, and we consider how investigating the entanglement of concepts can aid our understanding and help improve model robustness.</p
Crystal nucleation of griseofulvin as a model of medium-sized, flexible, and polymorphic active pharmaceutical ingredient (API)
No full textCrystallisation is an important purification and separation step for pharmaceutical industries. It can help to control desired properties such as solid-state, crystal habit and particle size, which can influence the bioavailability and manufacturability of the drug. Crystallisation is a two-step process involving nucleation, where a stable nucleus separates out of solution, and crystal growth, where the nucleus grows into the final crystal. The aim of this thesis is to investigate the crystal nucleation of griseofulvin as a model medium-sized, flexible, and polymorphic active pharmaceutical ingredient. In this work, we evaluated the effect of solvent, volume and agitation on the nucleation kinetics of griseofulvin. We also analysed the resulting solid form of griseofulvin crystallising in selected solvents.Griseofulvin nucleates fastest in acetonitrile, followed by n-butyl acetate and slowest in methanol. Analysis with classical nucleation theory indicates that both the pre-exponential factor and interfacial energy values were higher in methanol, followed by n-butyl acetate and lower in acetonitrile. The interfacial energy is well correlated to the order of ease of nucleation. Mesoscale clusters are present at the start of nucleation in acetonitrile and n-butyl acetate but not in methanol aligning with a non-classical nucleation theory mechanism. The larger size and higher concentration of mesoscale clusters in acetonitrile led to faster nucleation than in n-butyl acetate.For griseofulvin in methanol, volume and agitation process parameters do not impact the interfacial energy, as expected, but the pre-exponential factor does vary. The induction time for experiments at 100 mL are well correlated to energy dissipation with the incorporation of a term for critical supersaturation. Higher shear rate and energy dissipation lead to a decrease in induction times when examined within the same vessel. However, no clear correlation is observed between nucleation rate and mixing-related parameters when experiments across different systems are considered.Griseofulvin nucleates as the stable form I in methanol, as a previously reported solvated form in acetonitrile and as an unreported solvated form in n-butyl acetate. The desolvation of the solvated form in acetonitrile resulted in an unreported polymorphic form after drying at low humidity and room temperature. This new polymorphic form has a crystal structure related to most of the reported solvated forms of griseofulvin and can act as a host to specific guest species.In conclusion, solvent, volume and agitation are important parameters for the design of crystallisation processes and the knowledge of the solid form landscape is important for the development of new formulations of active pharmaceutical ingredients. Classical theory remains a valuable framework for understanding the crystallisation process and can be effectively supplemented by non-classical approaches when it fails to offer a satisfactory explanation. Although there has been some progress in understanding the scaling-up of crystallisation within similar crystallisers, comparing scales with different agitation mechanisms and detection methods remains a significant challenge.</p
So how does it feel to sing home?: An arts practice exploration of space, place and identity within my songwriting practice
No full textI am a singer songwriter and an Irish Traditional musician. My research challenges my own songwriting practice through an exploration of the themes of Space, Place, and Identity. A formulation of new methods of creative practice develops new insights and tools to inspire creativity more broadly.My early emigrant experience in the U.K. in the 1980’s was the ultimate impetus for this research. In being so abruptly removed from the Place I had always called home; it became vital for me to remember where I had come from and writing songs was both an effective and cathartic way of doing this. Although I returned to Ireland 20 years ago, those experiences remain central to my work as a songwriter and academic.So how does it feel to be home? Would you have come back sooner if you’d known? That the troubles inside would be stilled by the tide And hope the Atlantic provides (Home, 2002, Claire Watts)Being displaced has framed my experience as a songwriter, musician and scholar. My mother was Irish, and my father is English, and this meant that my childhood experience was shaped by a navigation between two very different cultural worlds, and this has led to my ongoing fascination into how Space and Place serves my sense of Identity as a singer songwriter.Grounded in a Practice as Research theoretical approach, my research project employs a variety of methodologies with evidencing based on a reflective analysis of my own practice while also drawing on material from interviews with other songwriters and feedback from two major performances completed during this PhD. The 12 songs created for this project are definite research outputs in themselves, but also serve as a means of documenting my process. This documentation of my process is further amplified through autoethnographic writing, reflections, photographs and excerpts from practice journals.The 5 chapters of this thesis document this research journey and the accompanying audio/visual recordings document the two major performances completed as part of this PhD.</p
Oxidative dehydrogenation of ethane (ODHE) to ethylene by bulk MoVNbTe mixed oxide M1 phase catalysts
No full textThe conversion of ethane to ethylene by steam cracking is an energy-intensive process that also produces significant global warming CO2 emissions. An alternative process that is not as energy-intensive and produces significantly less CO2 emissions is the oxidative dehydrogenation of ethane to ethylene by the bulk MoVNbTe mixed oxide catalyst. This paper reviews the current understanding of this catalytic reaction system to determine the nature of the bulk and surface phases of this important catalytic reaction. Although the crystalline M1 phase represents the bulk active phase, much is still unknown about the catalytic active surface sites of the M1 phase under reaction conditions. This review extensively examines the reported studies to date and outlines the experiments still needed to establish a fundamental structure-activity/selectivity relationship for this catalytic system that will guide the development of improved catalysts.</p
Development of flexible nanoporous gold electrodes for the detection of glucose
No full textThe development of implantable glucose sensors is of significant interest in the management of diabetes. This work focuses on developing an implantable, biocompatible nanoporous gold electrode prototype based on Kapton® for the subcutaneous detection of glucose. The electrodes were first modified with a layer containing glucose oxidase and Os(2,2′-bipyridine)2Cl⋅PVI (Os(bpy)2Cl PVI). An additional polymeric layer containing poly (2-methacryloyloxyethyl phosphorylcholine-co-glycidyl methacrylate) was then added to reduce biofouling and foreign body reaction effects. The modified electrode had a VMAX of 211 ± 13 μA cm− 2 and a KMapp of 6.1 ± 0.8 mM in pseudo physiological conditions, with a linear detection range from 1 to 4 mM and a sensitivity of 28.6 ± 2.1 μA cm− 2 mM− 1 . In artificial plasma, the response of the sensor was saturated at 3 mM, with a VMAX of 113 ± 10 μA cm− 2 and a KMapp of 2.1 ± 0.4 mM with a linear detection range from 1 to 2.5 mM and a sensitivity of 14.6 ± 3.3 μA cm− 2 mM− 1 . Mechanical stress testing demonstrated that there was a 40 % reduction of the redox polymer coverage after 320 deformation events, however the catalytic activity was still detectable after 160 events. Minimal cytotoxicity effects of the electrodes were observed. When subcutaneously implanted the electrodes showed fairly good mechanical stability after one week and detachment of the metallic layer on some electrodes after 21 days, probably due to electrode bending. A limited foreign body reaction was observed. These results indicated that the electrodes could be implanted for a period of up to 1 week.</p
Fine-tuning of gas uptake and selectivity in a hexafluorozirconate pillared coordination network that features two porous phases†
No full textHybrid coordination networks, sustained by divalent transition metal ions and a combination of organic and inorganic linker ligands, are an emerging class of physisorbents for adsorptive gas and vapour capture, especially under trace (≤1%) concentrations. Herein, we report a Cu(II) hybrid coordination network using the anionic pillar hexafluorozirconate ZrF6 2− , [Cu(pypz)2ZrF6]n; ZRFSIX-21-Cu (21 = 4-(3,5-dimethyl-1H-pyrazol-4-yl)pyridine). ZRFSIX-21-Cu possesses two ultramicroporous phases, a two-dimensional square lattice phase (α), and a three-dimensional primitive cubic unit phase (β), a rarity among hybrid ultramicroporous materials. Interestingly, ZRFSIX-21-Cu-α revealed better selectivity for C2H2 over CO2, and ZRFSIX-21-Cu-β for C2H2 over C2H4</p