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  • Author or Editor: Y. Naito x
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Abstract  

Heat capacities of U1–yLayO2 were measured by means of direct heating pulse calorimetry in the temperature range from 300 to 1500 K. An anomalous increase in the heat capacity curve of each sample was observed similarly to the case of U1–yGdyO2, found recently in our laboratory. As the lanthanum content of U1–yLayO2 increased, the onset temperature of an anomalous increase in the heat capacity decreased and the excess heat capacity increased. The enthalpy of activation (Hf) and the entropy of activation (Sf) of the thermally excited process, which cause the excess heat capacity were obtained to be 2.14, 1.63 and 1.50 eV and 39.4, 34.2 and 31.8 J·K–1·mol–1 for U0.956La0.044O2, U0.910La0.090O2 and U0.858La0.142O2, respectively. The values at zero La content extrapolated by using the data of Hf and Sf for U1–yLayO2 were in good agreement with the experimental values of undoped UO2 so far reported, similarly to the case of Gddoped UO2. The electrical conductivities of U1–yLayO2 (y=0.044 and 0.142) were also measured as a function temperature. No anomaly was seen in the electrical conductivity curve. It may be concluded that the excess heat capacity originates from the predominant contribution of the formation of oxygen clusters and from the small contribution of the formation of electron-hole pairs.

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The benefit of body weight resistance exercise with slow movement (BWRE-slow) for muscle function is well-documented, but not for energy metabolism. We aimed to examine physiological responses [e.g., energy expenditure (EE), respiratory exchange ratio (RER), and blood lactate (La)] during and after BWRE-slow compared to EE-matched treadmill walking (TW). Eight healthy young men (23.4 ± 1.8 years old, 171.2 ± 6.2 cm, 63.0 ± 4.8 kg) performed squat, push-up, lunge, heel-raise, hip-lift, and crunch exercises with BWRE-slow modality. Both the concentric and eccentric phases were set to 3 s. A total of three sets (10 repetitions) with 30 s rest between sets were performed for each exercise (26.5 min). On another day, subjects walked on a treadmill for 26.5 min during which EE during exercise was matched to that of BWRE-slow with the researcher controlling the treadmill speed manually. The time course changes of EE and RER were measured. The EE during exercise for BWRE-slow (92.6 ± 16.0 kcal for 26.5 min) was not significantly different from the EE during exercise for TW (95.5 ± 14.1 kcal, p = 0.36). BWRE-slow elicited greater recovery EE (40.55 ± 3.88 kcal for 30 min) than TW (37.61 ± 3.19 kcal, p = 0.029). RER was significantly higher in BWRE-slow during and 0–5 min after exercise, but became significantly lower during 25–30 min after exercise, suggesting greater lipid oxidation was induced about 30 min after exercise in BWRE-slow compared to TW. We also indicated that BWRE-slow has 3.1 metabolic equivalents in average, which is categorized as moderate-intensity physical activity.

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Summary Using a thermal relaxation calorimetry technique, we have measured heat capacities of κ-(BEDT-TTF)4Hg2.89Br8 system under magnetic fields between 0 and 6 T. With the increase of cooling rate from room temperature to liquid helium temperature, we have observed a remarkable but systematic tendency that the thermal anomaly associated with the superconductive transition shifts to the lower temperatures. The course of this phenomenon is attributable to the degree of disorder in the mercury chains which give an incommensurate potential to the superconducting planes.

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