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195 results on '"MacLaren, D. P."'

1. Controlled Evolution of Three-Dimensional Magnetic States in Strongly Coupled Cylindrical Nanowire Pairs

Author

Fullerton, J, Hierro-Rodriguez, A, Donnelly, C, Sanz-Hernández, D, Skoric, L, MacLaren, D A, and Fernández-Pacheco, A

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Cylindrical magnetic nanowires are promising systems for the development of three-dimensional spintronic devices. Here, we simulate the evolution of magnetic states during fabrication of strongly-coupled cylindrical nanowires with varying degrees of overlap. By varying the separation between wires, the relative strength of exchange and magnetostatic coupling can be tuned. Hence leading to the formation of six fundamental states as a function of both inter-wire separation and wire height. In particular, two complex three-dimensional magnetic states, a 3D Landau Pattern and a Helical Domain wall, are observed to emerge for intermediate overlap. The competition of magnetic interactions and the parallel growth scheme we follow (growing both wires at the same time) favours the formation of these anti-parallel metastable states. This works shows how the engineering of strongly coupled 3D nanostructures with competing interactions can be used to create complex spin textures.

Published
2022
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3. Engineering magnetic domain-wall structure in permalloy nanowires

Author

Benitez, M. J., Basith, M. A., McGrouther, D., McFadzean, S., MacLaren, D. A., Hrabec, A., Lamb, R. J., Marrows, C. H., and McVitie, S.

Subjects
Condensed Matter - Materials Science
Abstract

Using Lorentz transmission electron microscopy we investigate the behavior of domain walls pinned at non-topographic defects in Cr(3 nm)/Permalloy(10 nm)/Cr(5 nm) nanowires of width 500 nm. The pinning sites consist of linear defects where magnetic properties are modified by a Ga ion probe with diameter ~ 10 nm using a focused ion beam microscope. We study the detailed change of the modified region (which is on the scale of the focused ion spot) using electron energy loss spectroscopy and differential phase contrast imaging on an aberration (Cs) corrected scanning transmission electron microscope. The signal variation observed indicates that the region modified by the irradiation corresponds to ~ 40-50 nm despite the ion probe size of only 10 nm. Employing the Fresnel mode of Lorentz transmission electron microscopy, we show that it is possible to control the domain wall structure and its depinning strength not only via the irradiation dose but also the line orientation., Comment: Accepted for publication in Physical Review Applied

Published
2015

4. Enhanced thermoelectric performance in TiNiSn-based half-Heuslers

Author

Downie, R. A., MacLaren, D. A., Smith, R. I., and Bos, J. W. G.

Subjects
Condensed Matter - Materials Science
Abstract

Thermoelectric figures of merit, ZT > 0.5, have been obtained in arc-melted TiNiSn-based ingots. This promising conversion efficiency is due to a low lattice thermal conductivity, which is attributed to excess nickel in the half-Heusler structure.

Published
2013
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18. Strategies for Hydration and Energy Provision During Soccer-Specific Exercise.

Author

Clarke, N. D., Drust, B., MacLaren, D. P. M., and Reilly, T.

Subjects
HYDRATION, SOCCER, BEVERAGES, CARBOHYDRATES, GLYCERIN, DIETARY fats, INGESTION, HYDROCORTISONE, METABOLISM
Abstract

The aim of the present study was to investigate the effect of manipulating the provision of sports drink during soccer-specific exercise on metabolism and performance. Soccer players (N = 12) performed a soccer-specific protocol on three occasions. On two, 7 mL/kg carbohydrate-electrolyte (CHOv) or placebo (PLA) solutions were ingested at 0 and 45 min. On a third, the same total volume of carbohydrate-electrolyte was consumed (CHOf) in smaller volumes at 0, 15, 30, 45, 60, and 75 min. Plasma glucose, glycerol, non-esterified free fatty acids (NEFA), cortisol, and CHO oxidation were not significantly different between CHOv and CHOf (P >; 0.05). Sprint power was not significantly affected (P > 0.05) by the experimental trials. This study demonstrates when the total volume of carbohydrate consumed is equal, manipulating the timing and volume of ingestion elicits similar metabolic responses without affecting exercise performance. [ABSTRACT FROM AUTHOR]

Published
2005
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44. Chapter 8: Effect of carbohydrate supplementation on simulated exercise of rugby league referees.

Author

MacLaren, D. P. M. and Close, G. L.

Abstract

This investigation evaluated the effectiveness of supplementing eight elite rugby league referees with a 6% maltodextrin (Md) solution whilst undertaking a simulated rugby league game. The simulation was based on motion analysis of six rugby league matches. Subjects undertook two trials of repetitive 20-m shuttle activity on an indoor track. During one trial 200 ml of Md was ingested at eight time points and in the other trial a similarly tasting placebo (Pl) was administered. A single-blind, counterbalanced design was employed. The simulation involved subjects performing four, 10-min blocks of shuttle activity before a 10-min break was instigated. Three further 10-min blocks of shuttle activity were also performed before a performance test to volitional exhaustion involving 20-m shuttles at paces varying between 55 and 95% of a pre-determined O2 max was undertaken. Timed 15-m sprints took place during each of the 10-min blocks. The rating of perceived exertion (RPE), and blood glucose and lactate concentrations were also determined throughout. The mean number of shuttles to exhaustion was significantly greater with Md ingestion than with Pl ingestion (57 ± 19 vs. 43± 15; p <0.05), while the mean 15-m sprint times were significantly shorter for the Md than the P1 condition (2.40±0.09 s vs. 2.51 ±0.14 5; p<0.01). The mean RPE was 5.2% lower during Md than Pl ingestion, the values being significantly different (Md: 12.07±0.32; P1: 12.73±0.28; p<0.01). Maltodextrin ingestion significantly elevated blood glucose levels compared with placebo (F(1,7) = 18.07: p < 0.01), although no significant differences were apparent for blood lactate levels (F(1,7) = 4.39; p >0.05). These results highlight the beneficial effects of maltodextrin ingestion on work-rates of rugby league referees in a simulation of a game's activity. The improvement may be related to higher circulating concentrations of blood glucose. [ABSTRACT FROM AUTHOR]

Published
2002

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