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Cattle slurry application increases soil ecosystem resistance to flooding
No full textLand-spreading of animal slurry is a means of nutrient recycling and improving soil health. However, it can potentially alter soil ecosystem function and composition, thus representing a disturbance. Increasing incidences of extreme rainfall associated with climate change can compound the effects of such organic amendments on the soil microbial community. Here, we investigated three disturbance combinations (+slurry; +flood; +slurry+flood) and hypothesised that slurry addition would transiently alter the soil microbiome, potentially exacerbated by a subsequent flood, and that stability in the face of a flood would be enhanced by prior slurry addition. Resistance and resilience of microbial community structure (V4 16S rRNA sequencing; Illumina MiSeq) and function (carbon utilisation profiles and rates of respiration, litter decomposition, potential nitrification and potential denitrification) were assessed. Slurry addition increased basal respiration (+175 %), litter degradation (+250 %) and potential nitrification (+60 %) with rapid resilience (140 days post-application. Despite little change in soil microbial structure during flooding, we observed >50 % reductions in rates of litter decomposition and in both basal and substrate induced respiration, which were attenuated by a preceding slurry application, during the initial days of the flood. Finally, flooding slowed the rapid die-off of slurry-derived microbiota supporting 4-fold more slurry-taxa 6 days post-application. While slurry-spreading before light rainfall is preferred to reduce ammonia losses, accurate forecasting is vital to avoid application before heavy rainfall which could potentially enhance pathogen survival and transmission along the food chain.This research was supported by the Hardiman Scholarship Award and the Thomas Crawford Hayes Research fund from the University of Galway.peer-reviewe
Inhibition of hypersialylation in human intervertebral disc degeneration modulates inflammation and metabolism
No full textIntervertebral disc (IVD) degeneration is a major cause of low back pain (LBP), a significant global health burden. While glycosylation plays a key role in cellular signaling and inflammation, its role in IVD degeneration remains poorly understood. This study characterizes glycan alterations in human healthy and degenerated IVDs using glycomic (UPLC-MS, MALDI-IMS) and proteomic (LC-MS) analyses, combined with functional studies. These results identify hypersialylation, especially α-2,6-linked sialic acid, as a prominent feature of degenerated IVDs. In vitro inhibition of sialylation (3Fax-peracetyl Neu5Ac) in nucleus pulposus cells demonstrates reduced oxidative stress and inflammatory signaling, indicating a functional role for hypersialylation in IVD pathology. Targeting glycosylation pathways, notably sialylation, emerges as a promising therapeutic strategy for IVD degeneration.Research Ireland and the European Regional Development Fund (ERDF) under grant number 13/RC/2073_P2 and the European Commission's Horizon 2020 funding programme for the iPSpine project [grant number 825 925]. PREMUROSA H2020-MSCA-ITN-2019-860462
Two-stage gate control to minimize inrush current in piezoelectric transformer based inductorless ZVS converter
No full textA method to control the inrush current of inductorless converters based on piezoelectric transformers (PTs) with high input capacitance is presented. With no magnetic core, inductorless PT based converters are of particular interest in medical equipment intended for use in the vicinity of high magnetic fields. The proposed method involves applying a reduced gate voltage to the converter MOSFETs during start-up to increase their on-resistance and decrease dv/dt at the switching point. A higher gate voltage is applied once steady state PT conditions are established to provide efficient operation. The design of the proposed gate drive solution and detailed LTSpice simulation results are described for a 3.6 W, 20 V DC/810 Vpk AC inverter. Due to the lack of commercial PTs with characteristics suitable for ZVS, the design of an emulated PT circuit is described to enable validation by testing. Experimental results successfully validate simulation results for the proposed start-up circuit.This study and open access publication was supported by the College of Science and Engineering, University of Galway (Grant No. Hardiman PhD Scholarship - 2019)
Metasurface effect on the performance of planar antennas for wireless communications
No full textThis paper demonstrates the performance enhancement of a conventional planar antenna by incorporating metasurface (MTS) layer using a proposed unit-cell array. The impact of MTS unit-cell density on bit-error-rate (BER) and channel capacity (CC) in a point-to-point microwave link is investigated. The MTS layer is constructed from an array of identical unit-cells, including circular, square, and Jerusalem cross microstrip-line elements. The proposed H-shaped checkerboard antenna design is integrated with the MTS and evaluated for various unit-cell densities. Analytical scrutiny reveals significant enhancements in BER and CC with higher MTS unit-cell density, along with an increase in antenna gain through optimal MTS placement. This improvement is attributed to the MTS's ability to concentrate radiated energy within a narrower spatial region, optimizing signal transmission. Experimental validation shows a strong correlation between analytical predictions and measured results, confirming the effectiveness of our methodology. This study not only highlights the impact of MTS configurations on wireless channel performance but also provides valuable insights into the design and optimization of future wireless communication systems.Co‐funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Executive Agency. Neither the European Union nor the granting authority can be held responsible for them. Besides that, this publication has emanated from research jointly funded by Taighde Eireann—Research Ireland under Grant 13/RC/2094_2, the European Union's Marie Sklodowska‐Curie Actions under Grant 101126578 and was supported in part by University of Galway
Remote sensing applications for monitoring optically inactive water quality indicators: A comprehensive review
No full textMonitoring water quality (WQ) is crucial to ensure the safety and health of our water resources. Despite their importance, contemporary WQ monitoring programs are struggling with challenges such as high costs, limited spatio-temporal resolution, and data reliability issues. A promising solution to these challenges is the integration of remote sensing (RS) techniques with machine learning (ML) and artificial intelligence (AI) algorithms, which can significantly improve the efficiency and accuracy of WQ monitoring. Based on the literature, most of the studies have focused on optically active (OA)-WQ indicators like chlorophyll-a and colored dissolved organic matter, etc., while a few studies have been carried out focusing on optically inactive (OI)-WQ indicators. But WQ monitoring requires a number of OA- and OI-WQ indicators; for instance, the European Union Water Framework Directive (WFD) recommend 11 fundamental WQ indicators, which include both OA- and OI-WQ. Therefore, it is essential to consider both types of indicators in a regular WQ monitoring program to develop an effective water resources management plan. However, several recent studies have shown that the development of RS-based OI-WQ indicator retrieval model(s) introduces considerable uncertainty in the final retrieval results due to various factors. Additionally, these studies highlight that most of the retrieval models may not be suitable for global application. To highlight these challenges, the goal of the research is to conduct a comprehensive analysis of various RS data and existing techniques in order to more accurately retrieve OI-WQ indicators such as pH, dissolved oxygen (DOX), biological oxygen demand (BOD5), total phosphorus (TP), total nitrogen (TN), and dissolved inorganic nitrogen (DIN) in different waterbodies. To achieve the research objectives, this study conducted a critical review analysis of 105 research publications, including journal papers and conference papers, from 2005 to 2023. The study not only identified different types of satellite data, such as Landsat, Sentinel, and Aqua/Terra (MODIS), which are widely used, but also identified the advantages and disadvantages of different models, including empirical, semi-empirical, and ML/AI-based methods that are widely used in developing RS-driven retrieval model(s) for various OI-WQ indicators. Additionally, the study identified a range of opportunities (e.g., proposing a structural framework, reliable global model, etc.) and limitations (e.g., lack of in-situ data, structural framework, optimal RS wavelength for different OI-WQ indicators, etc.) in existing retrieval models. Moreover, the analysis suggests that advanced ML/AI approaches can be effective in retrieving OI-WQ indicators compared to other techniques in terms of retrieval data accuracy and reliability. The study also highlights current limitations of RS data and retrieval methods, such as spatial and temporal constraints, the need for improved calibration, and the demand for broader and more diverse training and testing datasets. Finally, the findings emphasize the significant potential of ML/AI algorithms in improving RS-based techniques for WQ monitoring, which may be more useful for water resource management and sustainable development strategies in the future.This research was funded by the Hardiman Research Scholarship of the University of Galway, which funded the first author as part of his PhD program
Bone biomechanics at the ultrastructural level: A finite element study using phase-field fracture modelling
No full textLamellar bone is a critical structural unit in cortical and trabecular bone at the sub-microscale, and consists of mineralised collagen fibrils (MCFs) made of hydroxyapatite (HA) minerals within staggered collagen molecules. These MCFs are surrounded by an extra-fibrillar matrix, containing HA minerals covered with non-collagenous proteins (NCPs). Traditionally, it was believed that most minerals resided within the MCFs, primarily in the gaps between collagen molecules. However, recent studies suggest that MCFs cannot accommodate the majority of minerals, with a significant portion existing outside the MCFs, reported as platelets or grains, wrapped around each fibril. Understanding bone mechanics at the sub-microscale and nanoscale—critical due to their influence on bone fragility—and requires thorough examinations of different parameters such as the content and distribution of minerals and their interaction with the organic matrix. This thesis investigates these aspects using finite element models and a multiscale homogenisation approach. At the nanoscale, detailed representative volume elements (RVEs) for MCFs and the extra-fibrillar matrix were developed. At the sub-microscale, several RVEs for lamellar bone were created to analyse each component's contribution to the bone's mechanical properties. This framework employs a homogenisation strategy to calculate effective elastic properties, meanwhile to study fracture properties, a phase field fracture model was developed and implemented. The analysis incorporates recent findings on the distribution of mineral platelets around collagen fibrils, enhancing the model's accuracy in predicting lamellar bone's mechanical response.
In the elastic regime, the results of showed that the extra-fibrillar matrix, rich in HA minerals and characterized by a highly ordered arrangement of mineral platelets along the MCFs, predominantly influences the tissue's elastic properties. This suggests that the extra-fibrillar matrix plays a more significant role in bone stiffness than previously assumed intra-fibrillar mineralisation. Beyond the elastic properties, the second study introduces a two-dimensional micromechanics damage-based RVE with a phase-field damage model to simulate fracture behaviour in lamellar bone, particularly under transverse loads. This advanced model emphasises the importance of mineral-mineral and mineral-fibril interactions, mediated by NCPs, in determining bone strength and toughness. It reveals that fractures often initiate in the mineral-rich extra-fibrillar matrix but are influenced by the presence and distribution of MCFs. MCFs do not affect crack path at low volume content. However, at high volume fraction depending on the interphase strength, MCFs can either facilitate or hinder crack propagation, affecting the tissue's fracture resistance and energy dissipation. Finally, the role of mineral morphology on mechanical performance was investigated, with the results showed that platelet-shaped minerals offer superior load-bearing capacity compared to granular forms. Both MCFs and extra-fibrillar platelet minerals act as barriers to crack propagation, significantly enhancing the tissue's toughness. These findings advance our understanding of bone mechanics across structural levels and underscore the complex interplay of mineral and organic components that contribute to lamellar bone's unique mechanical properties.European Research Council (ERC
Advancements in structural testing and life predictions of tidal turbine blades
No full textThe research explores advancements in structural testing and their outcomes to identify strategies for predicting the lifespan of tidal turbine blades with greater reliability, efficiency, and accuracy. In this context, as a case study, this research examines the structural testing results of a 5m-long crossflow helical tidal turbine foil. The advanced instrumentation, unbalanced rotating mass, and post inspection analysis used in the testing program improved data accuracy and result reliability, ensuring a more precise assessment of the turbine blade's structural performance. Moreover, validating the experimental results through FE modelling opens new avenues for utilising FE simulations as a viable alternative to traditional structural testing programs, which are often time consuming, expensive, and complex. Furthermore, this study identifies critical gap in structural testing of composite tidal turbine blades, particularly the limitation in assessing the impact of water absorption on composite materials under operational marine conditions. To address this challenge, the research proposes two FE modelling approaches to predict tidal turbine blades’ lifespan. Approach 1 integrates accelerated aged fatigue test data, while Approach 2 simulates water diffusion for material degradation. Validating these methods can improve sustainability of the tidal energy sector for clean and affordable energy solutions in the future.The authors extend grateful acknowledgment for the financial support received for this work from the European Commission under the H2020 CRIMSON project (Grant Agreement no.: 971209) and the TIDAL-GES project of the University of Galway Global Challenges Programme. Furthermore, gratitude is expressed for the funding from the MaREI Research Ireland Centre for Energy, Climate and Marine, which is funded by Taighde Éireann – Research Ireland, formerly Science Foundation Ireland, (Grant no. 12/RC/2302_2), the Sustainable Energy Authority of Ireland (Grant no. 22/RDD/783, 23/RDD/917 and 23/RDD/1021) and the Marine Institute, funded under the Marine Research Programme by the Government of Ireland (PDOC/21/03/01)
Nonlinear dispersive waves in soft elastic laminates under finite magneto–deformations
No full textLayered media can be used as acoustic filters, allowing only waves of certain frequencies to propagate. In soft magneto-active laminates, the shear wave band gaps (i.e., the frequency intervals for which shear waves cannot propagate) can be adjusted after fabrication by exploiting the magneto-elastic coupling. In the present study, the control of shear wave propagation in magneto-active stratified media is revisited by means of homogenisation theory, and extended to nonlinear waves of moderate amplitude. Building upon earlier works, the layers are modelled by means of a revised hard-magnetic material theory for which the total Cauchy stress is symmetric, and the incompressible elastic response is of generalised neo-Hookean type (encompassing Yeoh, Fung-Demiray, and Gent materials). Using asymptotic homogenisation, a nonlinear dispersive wave equation with cubic nonlinearity is derived, under certain simplifying assumptions. In passing, an effective strain energy function describing such laminates is obtained. The combined effects of nonlinearity and wave dispersion contribute to the formation of solitary waves, which are analysed using the homogenised wave equation and a modified Korteweg–de Vries (mKdV) approximation of the latter. The mKdV equation is compared to direct numerical simulations of the impact problem, and various consequences of these results are explored. In particular, we show that an upper bound for the speed of solitary waves can be adjusted by varying the applied magnetic field, or by modifying the properties of the microstructure.This project has received funding from the European Research Council (ERC) through Grant No. 852281 – MAGIC.peer-reviewe
Householders’ energy efficiency retrofit decisions – A review of the evidence
No full textImproving the energy efficiency of existing buildings through retrofitting is a challenge facing many countries. The European Commission's Renovation Wave Strategy proposes to double the annual energy retrofit rate of European residential buildings by 2030. Understanding householders' retrofit decision-making processes will help determine how to enable widescale retrofit uptake. A critical review of 164 studies was undertaken to (i) identify the factors which can influence retrofit decision-making, (ii) discuss the consistency of existing literature findings regarding the influence of factors on retrofit decision-making, (iii) add to existing literature by critiquing the evidence base, to identify the limitations of existing research on retrofit decision-making, and (iv) identify future research directions. 96 factors were identified as influences on retrofit decision-making. However, the paper found that the influence of many of these factors on householders' retrofit decision-making is understudied. In addition, the literature findings on the influence of many of these factors on retrofit decision-making are of mixed consistency. The influence of these factors varied depending on the dwelling, householder and household in question, the retrofit measures being considered or adopted, and depending on the stage of the retrofit decision-making process. However, this level of analysis is often missing in existing literature. Future research is needed that aims to understand the diverse range of influences on householders' retrofit decision-making, including how the influence changes depending on the householder, household or dwelling in question, depending on the retrofit measures being considered, planned, or adopted, and depending on the stage in the retrofit decision-making process.The financial support of the European Union's Horizon 2020 research and innovation programme (Grant agreement No. 839132 and Grant agreement No. 101036519), Science Foundation Ireland for the ERBE Centre for Doctoral Training (Grant agreement No. 18/EPSRC-CDT/3586), the MaREI Centre (Grant agreement no. 12/RC/2302_P2), and the Sustainable Energy Authority of Ireland (SEAI) (Grant No. RDD/492) is acknowledged
Improving radio-over-fiber systems using modulation instability phenomenon for satellite communication application
No full textThis letter proposes a low-cost, high-gain, low-noise microwave photonic structure using the modulation instability (MI) phenomenon for radio-over-fiber (RoF) systems. Conventionally, in modern satellite communication, the RoF structures always suffer from limitations of modulators that work at the high half-wave voltage (Vπ) in high frequency and high noise, especially in case of weak signal reception. We demonstrate how the MI phenomenon improves the modulator's bias voltage. Therefore it is also possible to obtain acceptable gain and reduce optical shot noise without any complications by employing the proposed structure. Our suggested RoF structure can operate in the desired frequency band using a fiber switching control system. Therefore, this system can reach a high gain by increasing the fiber length without needing external pumps. As a result, the SNR and the Vπ improve noticeably.Co-funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Executive Agency. Neither the European Union nor the granting authority can be held responsible for them. Besides that, this publication has emanated from research jointly funded by Taighde Éireann – Research Ireland under Grant number 13/RC/2094_2, the European Union’s Marie Sklodowska-Curie Actions under grant number 101126578 and was supported in part by University of Galway