Linear and nonlinear piezoelectric coefficients of second- and third-higher terms in length-extensional vibration were experimentally investigated in the compositions near the morphotropic phase boundary (MPB) of PbZrO3-PbTiO3-Pb(Mg1/3Nb2/3)O3 ternary piezoelectric ceramics. The Zr/Ti ratio showing the maximum value of the piezoelectric constant d 31 disagreed with that showing the maximum value of the electromechanical coefficient k 31 in the transverse vibration. The disagreement increased with Pb(Mg1/3Nb2/3)O3 (PMN) content. The nonlinear piezoelectric coefficients of the second- and third-higher terms showed their minimum values at the Zr/Ti ratios showing the maximum values of d 31. Hence, the Zr/Ti ratio showing the maximum value of d 31 was regarded as the MPB composition. The nonlinear coefficients of the second- and third-higher terms on the MPB compositions showed different dependences on PMN content. The nonlinear coefficient of the second-higher term showed a grain size dependence in its change, and that of the third-higher term showed a mechanical quality factor dependence in its change. The difference in the dependences was discussed from the viewpoint of the difference in the occurrence mechanism of nonlinear phenomena dominating the two nonlinear coefficients.

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In order to clarify the occurrence mechanism of nonlinear phenomena, dc-bias dependence and aging characteristics of the nonlinear coefficients of second-higher and third-higher terms were measured in piezoelectric rectangular vibrators. The two nonlinear coefficients of second-and third-higher terms were contrasted sharply in their dc-bias dependence and aging characteristics. These contrasting dependences originate from the difference in the occurrence mechanism of harmonic voltages, that determines the values of the second-and third-higher nonlinear coefficients. The difference in the occurrence mechanism was discussed from the viewpoint of non-180? domain-wall motion. Key-words : Nonlinear piezoelectric coefficient, Lead zirconate titanate, High-power vibration, Piezoelectric vibrator, dc-bias dependence, Aging 1. Introduction When lead zirconate titanate PZT piezoelectric ceramics are driven with a high power at frequencies around the resonance frequency after poling treatment, nonlinear phenomena such as current jumping and harmonic voltage generations are observed. These nonlinear phenomena restrict the operating range of devices, and simultaneously prevent operation stability.It is difficult to perform perfect poling in PZT ceramics for polycrystals. Nonoriented domains partially remain after poling treatment. We measured nonlinear coefficients of Pb Mg 13 Nb 23 O 3 PMN ceramics, which are paraelectric at room temperature, in order to investigate the influence of domains on nonlinear phenomena. The piezoelectric resonance of PMN ceramics was realized by applying a dc-bias field of 1400 Vmm. The nonlinear coefficient of the thirdhigher term of PMN ceramics without any domains was consequently about 1100 compared to that of PZT ceramics. Furthermore, current jumping appeared markedly in PZT but did not appear in PMN.1 These facts show that nonlinear phenomena are dominated by the existence of domains.In the development of practical materials suitable for high-power devices, the vibration velocity dependence of the mechanical quality factor and elastic constants were investigated.2 ,3 If the vibration velocity exceeds a threshold value, PZT ceramics become elastically soft and their mechanical quality factor decreases at the same time. This is the nonlinearity that observed as the change of linear coefficients. Since the 180c domain wall motion exerts no influence on the strain, the decrease in the mechanical quality factor and the change in elastic constant were probably caused by the motion of non-180c domain walls.

This study investigated the mechanism of reducing body fat via whey protein diet. Pregnant mice were fed whey or casein, and their offspring were fed by birth mothers. After weaning at 4 weeks, male pups received the diets administered to their birth mothers (n = 6 per group). At 12 weeks of age, body weight, fat mass, fasting blood glucose (FBG), insulin (IRI), homeostatic model assessment of insulin resistance (HOMA-IR), cholesterol (Cho), triglyceride (TG), the expression levels of lipid metabolism-related genes in liver tissues and metabolomic data of fat tissues were measured and compared between the groups. The birth weights of pups born were similar in the two groups. Compared to the pups in the casein group, at 12 weeks of age, pups in the whey group weighed less, had significantly lower fat mass, HOMA-IR and TG levels (p < 0.01, p = 0.02, p = 0.01, respectively), and significantly higher levels of the antioxidant glutathione and the anti-inflammatory 1-methylnicotinamide in fat tissues (p < 0.01, p = 0.04, respectively). No differences were observed in FBG, IRI, Cho levels (p = 0.75, p = 0.07, p = 0.63, respectively) and expression levels of lipid metabolism-related genes. Whey protein has more antioxidant and anti-inflammatory properties than casein protein, which may be its mechanism for reducing body fat.

The number of low birthweight (LBW) infants weighing below 2500 g has not decreased in Japan. This study aimed to develop an adult non-obese hyperglycemic mouse model born with LBW to study the pathogenesis. At 16.5 days of gestation, transient intrauterine ischemia (blocked blood flow in both uterine arteries for 15 min) was performed in a subgroup of pregnant mice (group I). Non-occluded dams were used as sham controls (group C). After birth, female pups in each group were weaned at 4 weeks of age and reared on the normal diet until 8 weeks of age (n = 7). Fasting blood glucose levels, serum immunoreactive insulin (IRI), and body composition were then measured. Metabolite analyses was performed on the liver tissues. Birthweight was significantly lower in group I compared with group C. Pups from group I remained underweight with low fat-free mass and showed hyperglycemia with high serum IRI and homeostasis model assessment of insulin resistance levels, indicating insulin resistance. Metabolite analyses showed significantly reduced adenosine triphosphate and nicotinamide adenine dinucleotide production and increased lactic acid in group I. The pathogenesis of our non-obese hyperglycemic mouse model may be due to increased myogenic insulin resistance based on mitochondrial dysfunction and reduced lean body mass.