Effects of Sixty-Minute Race-Pace Running on Cardiac Stress Biomarkers in Recreational Distance Runners.

Sudden cardiac death (SCD) in athletes is generally rare, but a serious complication of cardiovascular events during exercise. Although regular intensive physical exercise is thought to be a key to a healthy life, unsuspected pathologies might lead to SCD during or after physical activity. Cardiac dysfunction and elevated cardiac markers have been reported after prolonged exercise. We sought to clarify the cardiac marker levels and hydration status in healthy, middle-aged male subjects for 24 hours after running sixty-minute at race-pace. The participants were 47.4±1.7 years old, had peak oxygen consumption of 47.1±1.2ml/kg/min, and regularly running 70.5±6.4km/week. Blood biomarkers were performed before, immediately after, at the fourth and twenty-fourth hours after running. Compared to initial values, creatine kinase (before:161.2±22.5U/L, 24 hours after:411.9±139.7U/L, p<0.001) and CK-MB (before:4.3±0.7ng/ml, 24 hours after:10.1±3.0ng/ml, p<0.001) were significantly elevated immediately after running and remained significantly high for 24 hours. In addition, Troponin-I (before:5.0±1.1ng/l, 4 hours after:81.5±29.9ng/l, p<0.001) and NT-proBNP (before: 31.2±5.3pg/ml, immediately after: 64.4±8.5pg/ml, p<0.01) were significantly elevated immediately after running and returned to baseline levels in 24 hours. The sixty-minute running caused significant dehydration, but athletes were rehydrated at the 4th hour in their voluntary hydration behavior. As the individual data were analyzed, it was interesting to see that some of the athletes had critical biomarker levels without any cardiac symptom. Our findings indicate that race-pace sixty-minute running may induce a possible transient silent myocardial injury in apparently healthy master runners. Detailed pre-participation screening of these athletes may be necessary to reduce the risk of SCD.

Observations of Co4+ in a higher spin state and the increase in the Seebeck coefficient of thermoelectric Ca3Co4O9.

Ca3Co4O9 has a unique structure that leads to exceptionally high thermoelectric transport. Here we report the achievement of a 27% increase in the room-temperature in-plane Seebeck coefficient of Ca3Co4O9 thin films. We combine aberration-corrected Z-contrast imaging, atomic-column resolved electron energy-loss spectroscopy, and density-functional calculations to show that the increase is caused by stacking faults with Co4+-ions in a higher spin state compared to that of bulk Ca3Co4O9. The higher Seebeck coefficient makes the Ca3Co4O9 system suitable for many high temperature waste-heat-recovery applications.

Critical current density and flux pinning in BaFe1.9Pt0.1As2 and La doped Ba0.95La0.05Fe1.9Pt0.1As2 polycrystals.

We present the field and temperature dependence of the magnetizations of BaFe1.9Pt0.1As2 and Ba0.95La0.05Fe1.9Pt0.1As2 samples synthesized by solid-state reaction method. The samples were formed as a single phase in the ThCr2Si2-type structure. Replacing Ba with the smaller La atom results in a lattice shrinkage. The critical current, J c (H, T) has been determined (using Bean's critical state model) from magnetic hysteresis loops in a temperature range between T = 5 K and the superconducting transition temperatures (20 K), in fields up to H = 9 T. We find a nonmonotonic 'fishtail' shape (exhibiting a second peak) of the magnetization loops as well as a very large irreversibility. We observe a remarkable flux jump at T = 5 K for BaFe1.9Pt0.1As2 due to magneto-thermal instability, but a very sharp magnetization peak for Ba0.95La0.05Fe1.9Pt0.1As2 near H = 0, which corresponds to a much-reduced relaxation rate of vortices. J c decreases exponentially with temperature as well as with field in lower temperatures and fields ranges. La doping causes a considerable increase in the irreversibility, leading to a significant enhancement of J c. The analysis shows that the high J c is mainly due to collective (weak) pinning of vortices by dense microscopic point defects with some contribution from a strong pinning mechanism. The normalized pinning force F p/F p,max as a function of the reduced magnetic field h = H/H irr is also obtained. Using the approaches of Dew-Hughes (1974 Phil. Mag. 30 293) and Kramer (1973 J. Appl. Phys. 44 1360), we determine the nature of the pining sources. It is found that many different pinning mechanisms are active simultaneously. The modified expression of F p/F p,max based on collective pinning theory enables us to determine the field dependence of the relaxation rate S(H, T = 5 K) indirectly instead of using more difficult relaxation measurements. Finally, all drastic changes with La doping are clearly demonstrated and investigated under different models introduced in the literature.

Effect of substrate on the atomic structure and physical properties of thermoelectric Ca3Co4O9 thin films.

The incommensurately layered cobalt oxide Ca(3)Co(4)O(9) exhibits an unusually high Seebeck coefficient as a polycrystalline bulk material, making it ideally suited for many high temperature thermoelectric applications. In this paper, we investigate properties of Ca(3)Co(4)O(9) thin films grown on cubic perovskite SrTiO(3), LaAlO(3), and (La(0.3)Sr(0.7))(Al(0.65)Ta(0.35))O(3) substrates and on hexagonal Al(2)O(3) (sapphire) substrates using the pulsed laser deposition technique. X-ray diffraction and transmission electron microscopy analysis indicate strain-free growth of films, irrespective of the substrate. However, depending on the lattice and symmetry mismatch, defect-free growth of the hexagonal CoO(2) layer is stabilized only after a critical thickness and, in general, we observe the formation of a stable Ca(2)CoO(3) buffer layer near the substrate-film interface. Beyond this critical thickness, a large concentration of CoO(2) stacking faults is observed, possibly due to weak interlayer interaction in this layered material. We propose that these stacking faults have a significant impact on the Seebeck coefficient and we report higher values in thinner Ca(3)Co(4)O(9) films due to additional phonon scattering sites, necessary for improved thermoelectric properties.