Department of Mechanical, Polymer and Design
https://research.thea.ie/handle/20.500.12065/2412
2024-03-29T10:46:40ZPeak speed in Gaelic games: a systematic review of GPS methods
https://research.thea.ie/handle/20.500.12065/4752
Peak speed in Gaelic games: a systematic review of GPS methods
McGuinness, Eddie; Beattie, Kris; Lyons, Mark; Lane, Aoife; Higginbotham, Clement; Healy, Robin
Background: Peak speed is an essential physical quality in Gaelic games due to the offensive, defensive, and transitional nature of the sports. Objectives: The aims of the study were to systematically search the literature for studies examining peak speed during Gaelic games match-play using Global Positioning System (GPS) technology, to assess the GPS methodologies implemented and report normative values for peak speed by sport. Methods: Keywords were combined to search and identify studies reporting peak speed values recorded using GPS technology during Gaelic games match-play. Key details such as GPS brand/model, number of satellites connected, and firmware version were extracted. A risk of bias tool was designed to rate the level of detection bias within each study. Results: Twenty-one (N=21) studies met the inclusion criteria. Eight studies examined peak speed in hurling and men’s Gaelic football, respectively, while four camogie and one ladies Gaelic football study were identified. Twenty-nine percent (29%) of included studies were graded as having a high risk of bias in at least one category. Peak speeds between 7.81 to 9.97 m·s-1 were reported in hurling and men’s Gaelic football and between 5.88 to 7.45 m·s-1 in camogie and ladies’ Gaelic football. Conclusions: The dearth of literature examining peak speed in both female sports requires additional investigation, particularly in relation to the sprint profile of ladies Gaelic football. It is recommended that practitioners are cognisant of the methodological considerations which can be used as a ‘checklist’ to ensure accurate and reliable data are collected when using GPS technology to monitor peak speed
2023-10-31T00:00:00ZModification of bioactive hyaluronic acid for stereolithography 3D printing of hydrogel conduits for peripheral nerve regeneration
https://research.thea.ie/handle/20.500.12065/4669
Modification of bioactive hyaluronic acid for stereolithography 3D printing of hydrogel conduits for peripheral nerve regeneration
Buckley, Ciara
Peripheral nerve injuries occur as a result of illness or injury, and present a significant healthcare and economic burden. Many of these cases occur in otherwise healthy individuals, in the age range 20-40 years, due to trauma in the work environment. Despite all that is known of this condition, complete functional recovery remains difficult to obtain through current surgical methods.
The aim of this research was to modify hyaluronic acid (HA) to enable 3D printing of hydrogel nerve conduits which could enable full functional recovery of a peripheral nerve injury. An array of compounds were screened in conjunction with HA to assess any potential neurotrophic benefits to their inclusion in the final formulation.
As HA is not conducive to cell attachment, neuronal and glial cell lines were initially used to characterise HA in order to design a testing procedure and acquire a baseline response. HA was then successfully modified with cysteamine HCl and methacrylic anhydride, to produce thiolated HA (HA-SH) and methacrylated HA (HA-MA) respectively, as confirmed by colorimetric and spectroscopic methods. The modification degree was approximately 20% so as not to interfere with the receptor interaction of HA. Modified HA was characterised chemically and biologically to ensure cytocompatibility in neuronal and glial cell lines. UV photo-polymerised hydrogels were created via click chemistry reactions by combining thiolated HA and methacrylated HA in various ratios and their properties were evaluated. Due to the poor mechanical properties of the HA hydrogels, a synthetic polymer, polyethylene glycol dimethacrylate (PEGDMA), was introduced to the matrix. An optimal formulation was discovered and prints were created via stereolithography 3D printing. Direct contact and elution extract testing revealed no significant cytotoxicity over a 24 h period, in contrast to the hydrogels of each of the four polymeric matrices tested (PEGDMA, 50 %wv HA-MA: PEGDMA, 50 %wv HA-SH: PEGDMA and hybrid blend). This would indicate that 3D printing yielded a sample which is representative of the conduit formulation, which is capable of providing biological and physical support to enhance peripheral nerve regeneration.
Through extensive testing of potential neurotrophic compounds, the lead compound Tyrosol failed to produce significant proliferative effects from elution extract testing of 3D printed samples using the resazurin assay. Given its antioxidant status and the significant proliferative effects observed with this compound in direct cell assays, future studies should
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refine the test methods in order to evaluate the effective elution concentration of Tyrosol from the final conduit, rather than from a representative sample.
This research could have a significant impact on the future of not only nerve regeneration, but also bioengineering as a whole. This thesis has elucidated the use of click-chemistry reactions to enable highly reliable cross-linking reactions in biological polymers to enable processing which would otherwise be difficult. Further work would involve the ex vivo testing of this formulation in dorsal root ganglion cells before in vivo testing could take place. This formulation could also be tested in other formats such as injectable hydrogels and foams for a number of pathologies
2023-01-01T00:00:00ZEffect of mechanical recycling on the mechanical properties of PLA-based natural fiber-reinforced composites
https://research.thea.ie/handle/20.500.12065/4469
Effect of mechanical recycling on the mechanical properties of PLA-based natural fiber-reinforced composites
Finnerty, James; Rowe, Steven; Howard, Trevor; Connolly, Shane; Doran, Christopher; Devine, Declan M.; Gatley, Noel M.; Chyzna, Vlasta; Portela, Alex; Bezerra, Gilberto S.N.; McDonald, Paul; Colbert, Declan Mary
The present study investigates the feasibility of utilizing polylactic acid (PLA) and PLAbased
natural fiber-reinforced composites (NFRCs) in mechanical recycling. A conical twin screw
extrusion (CTSE) process was utilized to recycle PLA and PLA-based NFRCs consisting of 90 wt.%
PLA and a 10 wt.% proportion of either basalt fibers (BFs) or halloysite nanotubes (HNTs) for up
to six recycling steps. The recycled material was then injection molded to produce standard test
specimens for impact strength and tensile property analysis. The mechanical recycling of virgin
PLA led to significant discoloration of the polymer, indicating degradation during the thermal
processing of the polymer due to the formation of chromatophores in the structure. Differential
scanning calorimetry (DSC) analysis revealed an increase in glass transition temperature (Tg) with
respect to increased recycling steps, indicating an increased content of crystallinity in the PLA. Impact
strength testing showed no significant detrimental effects on the NFRCs’ impact strength up to
six recycling steps. Tensile testing of PLA/HNT NFRCs likewise did not show major decreases in
values when tested. However, PLA/BF NFRCs exhibited a significant decrease in tensile properties
after three recycling steps, likely due to a reduction in fiber length beyond the critical fiber length.
Scanning electron microscopy (SEM) of the fracture surface of impact specimens revealed a decrease
in fiber length with respect to increased recycling steps, as well as poor interfacial adhesion between
BF and PLA. This study presents a promising initial view into the mechanical recyclability of PLAbased
composites.
2023-04-06T00:00:00ZImprovement of rheological and mechanical properties of PLA by reactive blending with Poly(MMA-g-GMA)
https://research.thea.ie/handle/20.500.12065/4404
Improvement of rheological and mechanical properties of PLA by reactive blending with Poly(MMA-g-GMA)
Karimi, Amirhussein; Garmabi, Hamid; Javadi, Azizeh; Ahmadi, Mostafa
The aim of this study is to improve the melt strength of Polylacticacid (PLA) using
methylmethacrylate-g-glycidylmethacrylate copolymers, Poly(MMA-g-GMA), that was
synthesized by reactive blending at different weight fractions of GMA from 6 to 10 %.
Copolymers were blended with polylacticacid (PLA) in internal mixer at different weight fractions
from 0%, 6% and 8% as chain extender to modify the rheological behavior. The properties of neat
PLA and modified PLA were characterized by Differential Scanning Calorimetry (DSC) and
Rheometric Mechanical Spectrometer (RMS). The balanced torque was increased by increasing
the fraction of copolymer chain extender. The results showed that Poly(MMA-g-GMA) is an
effective chain extender for PLA. The glass transition temperature of PLA was also changed by
blending with the synthesized copolymer. The blending affected the cold crystallization behavior
and melting behavior of PLA, as well. Dynamic moduli also showed higher viscosities that can
lead to higher melt strength.
2017-06-26T00:00:00Z