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La₂ O₃를 첨가한 Pb(Zr,Ti)0₃자기의 유전특성에 낟알 크기가 미치는 효과
金顯男,鄭相九,宋龍鎭 亞洲大學校 1986 論文集 Vol.9 No.-
Pb(Zr??Ti??)O₃ + lmol%La₂O₃ ceramics of which the mean grain sizes were 2.5, 2.8, 3.5μm respectively were prepared. The dielectric constant and the dissipation factor of them with evaporated gold electrodes were measured as a function of temperature. As the grain size decreases, the Curie temperature T?? increases slightly, the peak height of the dielectric constant curve decreases, and the peak width of the dielectric constant curve increases. The dielectric constant at room temperature remains constant regardless of the grain size. A model was followed which proposeds that each grain has a different phase transition temperature T?' and the distribution of T?' follows the Gaussian distribution. It was also assumed that each grain follows the Curie-Weiss law for T>T?' The relevant parameters were determined by the least square fit method by computer calculation. The above experimental results were explained by this model, and the variations of the parameters due to the variation of grain size were discussed. The dominant factor for the grain size e fects seems to be the inhomogeneity of the concentration of impurities.
송용진,권성춘 대한약리학회 2004 The Korean Journal of Physiology & Pharmacology Vol.8 No.6
The present study were designed to characterize the action mechanisms of acetylcholine (ACh)- induced endothelium-dependent relaxation in arteries precontracted with high K+ (70 mM). For this, we simultaneously measured both muscle tension and cytosolic free Ca2+ concentration ([Ca2+]i), using fura-2, in endothelium-intact, rabbit carotid arterial strips. In the artery with endothelium, high K+ increased both [Ca2+]i and muscle tension whereas ACh (10μM) significantly relaxed the muscle and increased [Ca2+]i. In the presence of NG-nitro-L-arginine (L-NAME, 0.1 mM), ACh increased [Ca2+]i without relaxing the muscle. In the artery without endothelium, high K+ increased both [Ca2+]i and muscle tension although ACh was ineffective. 4-DAMP (10 nM) or atropine (0.1μM) abolished ACh-induced increase in [Ca2+]i and relaxation. The increase of [Ca2+]i and vasorelaxation by ACh was siginificantly reduced by either 3μM gadolinium, 10μM lanthanum, or by 10μM SKF 96365. These results suggest that in rabbit carotid artery, ACh-evoked relaxation of 70 mM K+-induced contractions appears to be mediated by the release of NO. ACh-evoked vasorelaxation is mediated via the M3 subtype, and activation of the M3 subtype is suggested to stimulate nonselective cation channels, leading to increase of [Ca2+]i in endothelial cells.
The braidings in the mapping class groups of surfaces
송용진 대한수학회 2013 대한수학회지 Vol.50 No.4
The disjoint union of mapping class groups of surfaces formsa braided monoidal category M, as the disjoint union of the braid groups B does. We give a concrete and geometric meaning of the braidings βr,s in M. Moreover, we nd a set of elements in the mapping class groupswhich correspond to the standard generators of the braid groups. Usingthis, we can dene an obvious map ø : Bg → Γg,1. We show that this map ø is injective and nongeometric in the sense of Wajnryb. Since thismap extends to a braided monoidal functor Ф : B → M, the integralhomology homomorphism induced by ø is trivial in the stable range.