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  • Author or Editor: R. Ogasawara x
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Abstract  

The focus of this work is the use of thermal analyses and Fourier Transform Infrared Spectroscopy (FTIR) for characterization of the gel decomposition, resulting from the formation of Y-barium hexaferrite substituted by Zn ions (Zn-Y-barium hexaferrite). Samples with Ba2Zn2Fe12O22 composition were synthesized by the citrate auto-combustion method. During the TG experiments the highest mass loss was attributed to citrate decomposition owing to the self-combustion reaction, confirmed by the disappearance of –OH band, and the drastic decrease of –CO2 and –NO3 bands. Zn substitution resulted in an X-band microwave absorber material.

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Low-intensity resistance exercise with blood flow restriction (BFR) has been shown to induce a prominent increase in muscle activation in response to muscle fatigue. However, the magnitude of muscle fatigue between continuous (Con-BFR) and intermittent BFR (Int-BFR, BFR only during exercise) is currently unknown. We examined the effect of Con-BFR or Int-BFR on muscle activation during exercise. Unilateral arm curl exercise (20% of one-repetition maximum, four sets, 30 sec rest period between sets) was performed without (CON) or with Con-BFR or Int-BFR. During BFR conditions, the cuff was inflated to 160 mmHg on the proximal region of testing arm. Surface electromyography (EMG) was recorded from the biceps brachii muscle, and integrated EMG (iEMG) was analyzed. During the exercise, iEMG increased progressively in Con-BFR and Int-BFR and both conditions were greater (p < 0.05) than CON at the 3rd and 4th set. However, there were no differences (p > 0.05) in iEMG between Con-BFR and Int-BFR during exercise (∼2.45 and ∼2.40 times, respectively). Thus, the magnitude of increase in muscle activation may be similar between Con-BFR and Int-BFR when BFR exercise was performed at a high level of cuff pressure intensity.

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