• Title/Summary/Keyword: J48

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Laser Photobiostimulation-Induced Hypoalgesia in Rats (쥐에 대한 레이저 자극시 진통효과)

  • Kwak, Hyun-Ho;Kim, Do-Hyung;Choi, Hyun-Hee;Yi, Chung-Hwi
    • Physical Therapy Korea
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    • v.5 no.2
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    • pp.15-22
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    • 1998

  • Laser photobiostimulation (LPBS) is one of the recent additions to therapeutic procedures used in chronic pain management. Though widely used, a clear understanding of its mechanism of action was not disclosed. In addition, the energy density that produces maximal benefit has not yet been established. The purposes of this study were to determine the effects of LPBS on pain relief in rat and to determine treatment dosage. Eight, 8-week old female, Sprague-Dawley rats were employed. All subjects were assigned to one of four groups: a sham laser group, a 0.4 $J/cm^2$ laser group, a 2.0 $J/cm^2$ laser group, and a 6.0 $J/cm^2$ laser group. Ga-As laser (904 nm wavelength) of three different energy densities (0.4, 2.0, 6.0 $J/cm^2$) was applied on a tail acupuncture point and tail-flick latencies were measured five times pre-and post-treatment as following schedules: 30 minutes, 1 hour. 24 hours. 48 hours, and 7 days later. An increase in pain threshold was demonstrated following LPBS, employing rat tail-flick test. LPBS of 2.0 $J/cm^2$ produced hypoalgesia of rapid onset and short duration (1 hour, 24 hours) while the response to 6.0 $J/cm^2$ was delayed and lasted longer (48 hours, 7 days). LPBS of 0.4 $J/cm^2$ did not produce any hypoalgesia.

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Sintering phenomena and grain growth of ultra-fine spinel($MgAl_2O_4$);(II) (순수 스피넬($MgAl_2O_4$)의 입성장 및 소결현상)

  • 이형복;한영환
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.3
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    • pp.498-502
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    • 1998

  • Sintering phenomena at refractory temperature ranges, from $1400^{\circ}C$ to $1700^{\circ}C$, of the pure spinel $(MgAl_2O_4)$ are analysed and compared to the experimental data from other researchers in terms of grain size(G), density($\rho$), and activation energy(Q). The grain size and relative density relationships for the spinels present very similar trends. They exhibit two distinct regions, an intermediate sintering stage to about the 85~90% density level and what appears to be the final stage sintering region above that transition-density level. The activation energy in terms of the grain size (G) and density ($\rho$) is determined to be 670$\pm$48 (kJ/mol) in this spinel and about 590 kJ/mol for the overall temperature range in other's spinel. These values are close to other published data, 360 to 580 kJ/mol.

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