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This study investigated the causes of microstructural changes and the resultant electrical properties according to the sintering temperature of 0.96(K0.46−xNa0.54−x)Nb0.95Sb0.05O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3 lead-free ceramics by analyzing the correlation between vacancy concentrations and 2D nucleation. When sintered for 4 h, no grain growth occurred for the x = 0.000 composition over a wide temperature range, demonstrating that the existence of initial vacancies is essential for grain growth. As x increased, that is, as the vacancy concentration increased, the critical driving force (ΔGC) for 2D nucleation decreased, and abnormal grain growth was promoted. The number and size of these abnormal grains increased as the sintering temperature increased, but at sintering temperatures above 1100 °C, they decreased again owing to a large drop in ΔGC. The x = 0.005 specimen sintered at 1085 °C exhibited excellent piezoelectric properties of d33 = 498 pC/N and kp = 0.45 due to the large number of large abnormal grains with an 83% tetragonal phase fraction. The x = 0.000 specimen sintered at 1130 °C with suppressed grain growth exhibited good energy storage properties because of its very high relative density and small grain size of 300 to 400 nm. [ABSTRACT FROM AUTHOR]

Portulaca oleracea L. is a traditional oriental medicine known for its pharmacological effects. The present study aimed to investigate the immunostimulatory effects of PPCE on cyclophosphamide-stimulated rat model and in isolated spleen cells. The result showed that PPCE exerted an immunostimulatory effect in vivo and in vitro. Specifically, PPCE significantly enhanced splenocyte proliferation and upregulated inflammatory cytokines (IL-2, IL-12, TNF-α, and IFN-γ) and NK cell activity in vitro. The immunostimulatory effect was further investigated through various immunological assays. Oral administration of PPCE increased the swimming time and number of immune cells in rats. Histological analysis revealed that PPCE administration exerted splenic recovery. Thus, P. oleracea L. based complex extracts may be used as an immunostimulatory agent in medicine or functional foods. [ABSTRACT FROM AUTHOR]