The effect of carbohydrate ingestion on the motor skill proficiency of soccer players

This study examined the effects of ingesting a glucose-polymer (GP) solution on the motor skill proficiencies of association football (soccer) players from two teams playing during two matches in a cool environment. Fifteen minutes before each match and at halftime, players from both teams ingested 5 ml/kg of either placebo or a 6.9% GP solution. GP ingestion did not improve tackling, heading, dribbling, or shooting ability. On the contrary, the mean of successful tackles was lower with GP ingestion than with placebo. The success rate for heading, dribbling, and shooting also tended to be lower in the GP than in the placebo condition. In contrast, success in passing and ball control was similar in the two conditions. Improvements in passing and ball control may have been related to a decrease in the intensity of play in the second half of the game. These data indicate that there are no measurable benefits of GP ingestion for the motor skill proficiencies of soccer players during games played in a cool environment.IS

Porous silica-pillared MXenes with controllable interlayer distances for long-life Na-ion batteries

MXenes are a recently discovered class of two-dimensional materials that have shown great potential as electrodes in electrochemical energy storage devices. Despite their promise in this area, MXenes can still suffer limitations in the form of restricted ion accessibility between the closely spaced multistacked MXene layers, causing low capacities and poor cycle life. Pillaring, a strategy where a secondary species is inserted between layers, has been used to increase interlayer spacings in clays with great success, but has had limited application in MXenes. We report a new amine-assisted pillaring methodology that successfully intercalates silica-based pillars between Ti3C2 layers. Using this technique, the interlayer spacing can be controlled with the choice of amine and calcination temperature, up to a maximum of 3.2 nm, the largest interlayer spacing reported for an MXene. Another effect of the pillaring is a dramatic increase in surface area, achieving BET surface areas of 235 m2 g-1, a sixty-fold increase over the unpillared material and the highest reported for MXenes using an intercalation-based method. The intercalation mechanism was revealed by different characterisation techniques, allowing the surface chemistry to be optimised for the pillaring process. The porous MXene was tested for Na-ion battery applications, and showed superior capacity, rate capability and remarkable stability compared with non-pillared materials, retaining 98.5% capacity between the 50th and 100th cycles. These results demonstrate the applicability and promise of pillaring techniques applied to MXenes, providing a new approach to optimising their properties for a range of applications. Porous MXenes are very promising materials for a range of applications including energy storage, conversion, catalysis and gas separations

Muscle fatigue resistance during stimulated contractions is reduced in young male smokers.

Aim: To determine whether muscle function is compromised in healthy smokers in comparison with activity-matched non-smokers. Methods: Nine male smokers (aged 22.2 ± 2.5 years: mean ± SD) with a smoking history of 2.5 ± 3.1 pack years, and ten male control participants (25.4 ± 2.9 years) matched for physical activity level participated in this study. Knee extensor strength was measured using isometric maximal voluntary contractions. Voluntary activation of the quadriceps and co-activation of the biceps femoris were determined using interpolated twitches and surface electromyography respectively. The frequency-torque relationship and fatigue resistance were assessed with electrically evoked contractions. A fatigue index was determined as the ratio of final torque to initial torque during a series of isometric contractions (2 min; 30 Hz; 1 s contraction/1 s rest). Quadriceps anatomical cross sectional area was measured with MRI at 50% of femur length. Results: Maximal voluntary contraction torque, quadriceps anatomical cross sectional area, knee extensor torque/quadriceps cross sectional area, activation, co-activation and force-frequency relationship were similar, whereas the fatigue index was 17% lower in smokers than non-smokers. Conclusion: In young men smoking does not significantly affect quadriceps muscle mass and contractile properties, but does reduce fatigue resistance of the quadriceps muscle, which was not attributable to differences in physical activity. © 2007 The Authors

Observations of metals in the intra-cluster medium

Because of their deep gravitational potential wells, clusters of galaxies retain all the metals produced by the stellar populations of the member galaxies. Most of these metals reside in the hot plasma which dominates the baryon content of clusters. This makes them excellent laboratories for the study of the nucleosynthesis and chemical enrichment history of the Universe. Here we review the history, current possibilities and limitations of the abundance studies, and the present observational status of X-ray measurements of the chemical composition of the intra-cluster medium. We summarise the latest progress in using the abundance patterns in clusters to put constraints on theoretical models of supernovae and we show how cluster abundances provide new insights into the star-formation history of the Universe.Comment: 28 pages, 12 figures, accepted for publication in Space Science Reviews, special issue "Clusters of galaxies: beyond the thermal view", Editor J.S. Kaastra, Chapter 16; work done by an international team at the International Space Science Institute (ISSI), Bern, organised by J.S. Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke

The Future Landscape of High-Redshift Galaxy Cluster Science

Large scale structure and cosmolog