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Naoyuki Tateiwa,Yoshinori Haga,Tatsuma D. Matsuda,Etsuji Yamamoto,Yoshichika Onuki,Zachary Fisk 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
We have studied the high-pressure magnetic property in UGe2 where ferromagnetic superconductivityappears under high pressure. In this study, we focus on the magnetic property at pressuresabove the ferromagnetic critical pressure Pc =1.6 GPa. The temperature and magnetic field dependencesof the dc-magnetization have been measured under high pressures up to 5.1 GPa by using aceramic anvil high pressure cell. At pressures above Pc, the magnetic susceptibility χ shows a broadmaximum around Tχmax and the magnetization at 2.0 K shows an abrupt increase (metamagnetictransition) at Hc. With increasing pressure, the peak structure in χ becomes broader, and thepeak position Tχmax moves to the higher temperature region. The metamagnetic field Hc increasesrapidly with increasing pressure. At pressures above 4.1 GPa, χ shows a simple temperature dependence,and the magnetization increases linearly with increasing field. These phenomena in UGe2resemble to those in the intermetallic compounds of 3d transition metals such as Co(S1−xSex) andYCo2. We discuss the experimental results by using the phenomenological spin-fluctuation theory.
Magnetic Phase Diagram of UCoAl
Tatsuma D. Matsuda,Naoyuki Tateiwa,Etsuji Yamamoto,Yoshinori Haga,Yoshichika Onuki,Dai Aoki,Jacques Flouquet,Zachary Fisk 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
We report precision c-axis magnetic measurements on a high-quality single crystal of the heavyfermion metamagnet UCoAl. The metamagnetic transition at HM changes from 1st order at lowtemperature to a crossover at high temperature. HM is nearly linearly increasing with increasingtemperature up to a critical temperature T0. The critical temperature T0 is determined from boththe field and the temperature dependences of magnetization to be 11 K. The field dependence ofthe Sommerfeld coefficientis estimated from M(T) by using a Maxwell relation. (H) shows astep-like decrease at HM. This behavior is consistent with the previous reports of specific heat andresistivity measurements at low temperatures.
Effects of Val-Pro-Pro and Ile-Pro-Pro on Nondipper Patients: A Preliminary Study
Mari Takahashi Kurosawa,Yasunori Nakamura,Naoyuki Yamamoto,Kazuhisa Yamada,Toshiro Iketani 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.5
Much clinical evidence on the antihypertensive effects of the milk-derived antihypertensive peptides Val-Pro-Pro and Ile-Pro-Pro (lactotripeptides) has been reported. However, circadian rhythm effects determined by ambulatory blood pressure monitoring (ABPM) to eliminate the confounding influence of the white-coat effect have not been fully studied. Twelve hypertensive patients not receiving antihypertensive medication (2 men, 10 women; mean age±standard deviation, 63.5±8.3 years) who had been visiting our clinic for more than 1 year participated in this study. Mean (±standard deviation) systolic blood pressure (SBP) and diastolic blood pressure (DBP) were 142.4±2.6 and 83.5±6.4 mm Hg, respectively, at the first office visit. After patients ingested a fermented milk product containing antihypertensive peptides (2.53 mg Val-Pro-Pro; 1.52 mg Ile-Pro-Pro) for more than 4 weeks, both office SBP and DBP were significantly reduced to a mean (±standard deviation) of 133.3±7.0 mm Hg and 76.5±8.4 mm Hg (P<.001 and P<.005 by paired t-test), respectively. The 24-hour SBP and DBP determined by ABPM were reduced from 127.3±2.4 and 78.7±2.3 mm Hg to 120.2±2.4 and 75.0±2.2 mm Hg (P<.001 and P<.05), respectively. Awake-time SBP (08:00–21:00), night-time SBP (0:00–05:00), and early-morning SBP (06:00–07:00) were reduced from 130.9±2.4 to 123.3±2.3 mm Hg, 118.7±2.9 to 113.2±3.4 mm Hg, and 132.8±4.3 to 122.4±3.9 mm Hg (by paired t-test: P<.001, P<.05, and P<.05), respectively. As seen with DBP measured by ABPM, 24-hour DBP and awake-time DBP were significantly reduced from 78.7±2.3 to 75.0±2.2 mm Hg and 82.1±2.5 to 77.3±2.2 mm Hg (P<.05 and P<.01), respectively. Office BP and 24-hour blood pressure did not significantly differ between the dipper and nondipper groups at baseline. However, after treatment, night-time and early-morning blood pressure were significantly reduced from baseline in the nondipper group (−8.5±2.5 and −15.6±3.7 mm Hg; P<.05 and P<.01, respectively) but not in the dipper group (−2.5±3.6 and −1.2±4.7 mm Hg; P not significant), and the reduction in early-morning blood pressure significantly differed between the groups (P<.05). These results suggest that Val-Pro-Pro and Ile-Pro-Pro decrease blood pressure in patients with stage I hypertension and result not only in lower blood pressure at night-time but also in lower early-morning SBP in nondipper patients.
Teppei Nakamura,Jun Mizutani,Kouichi Sasaki,Naoyuki Yamamoto,Kenji Takazawa 한국식품영양과학회 2009 Journal of medicinal food Vol.12 No.6
Pharmaceutical angiotensin-converting enzyme (ACE) inhibitors have been shown to reduce arterial stiffness; the possible effect of food-derived putative ACE inhibitory peptides on this degenerative process, however, has not been reported. In the present study, casein hydrolysate containing the lactotripeptides, Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP), which has been found to have an antihypertensive effect in a number of clinical studies, was investigated for its ability to improve hemodynamic parameters, including central systolic blood pressure (cSBP), in hypertensive subjects. Twelve hypertensive subjects who were not on prescribed medication were monitored for various hemodynamic parameters, including brachial blood pressure (peripheral blood pressure), cSBP, and augmentation index (AI), at the start and then after 3, 6, and 9 weeks of a daily treatment comprising four tablets containing VPP and IPP. Compared with basal levels, treatment with casein hydrolysate for 6 and/or 9 weeks showed a significant reduction in peripheral systolic and diastolic blood pressure, AI, and cSBP, but not in heart rate or pulse pressure. cSBP showed a reduction sooner and greater (−21.8mm Hg) than did brachial systolic blood pressure (−16.4mm Hg) during the 9-week treatment. Although small and not placebo-controlled, this study suggests that continuous intake of VPP and IPP might have the potential to improve arterial stiffness as well as cSBP and peripheral brachial blood pressure.
Single Crystal Growth and Physical Properties of UT2Al20 (T=Transition Metal)
Yuji Matsumoto,Tatsuma D. Matsuda,Naoyuki Tateiwa,Etsuji Yamamoto,Yoshinori Haga,Zachary Fisk 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
We have studied the single crystal growth and the physical properties of the UT2Al20 system. Wehave successfully grown UT2Al20 (T = Cr, Ti, W and Mo) using Al self flux and have characterizedthe crystals using electron probe microanalyzer (EPAM) and X-ray diffractometer. We have alsomeasured their magnetic and electric properties. The ground states of UT2Al20 (T = Cr, Mo andW ) are Pauli paramagnetic as is likely also in UTi2Al20. The effective masses of UCr2Al20 andUTi2Al20 are only weakly enhanced.
Sae Yanagihara,Shinji Fukuda,Hiroshi Ohno,Naoyuki Yamamoto 한국식품영양과학회 2012 Journal of medicinal food Vol.15 No.6
To understand host gastrointestinal response after exposure to probiotic Lactobacillus acidophilus L-92,microarray analysis of cultured epithelial Caco-2 cells was performed. Of the 187 genes down-regulated after 4 h treatment with L-92, 25 were involved in RNA splicing; 12, in cell cycle; 8 were transcriptional regulators; 2 were involved in ubiquitin proteolysis; 2, in adhesion; 2, in meiosis; 2, in splicing; and 2 encoding cytokines. In the RNA splicing group, genes encoding small nuclear RNAs, nuclear pore complex interacting proteins, RNA binding motif proteins, and SMG1 homologs (phosphatidylinositol 3-kinase-related kinase) were identified. Among the only 13 genes up-regulated by the treatment, 5 were involved in histone structure, and 2 were involved in metabolism. Genes belonging to cell adhesion, transmembrane proteins,mitogen-activated protein kinase, immune response, DNA binding, inflammation, and protein synthesis groups were mainly up-regulated after 20 h of treatment, whereas no significantly down-regulated genes were observed. In the present transcriptome analysis, during the early stage of treatment (four hours of treatment) with L-92, genes involved in cell growth and cell meiosis were mainly repressed. During the late phase of treatment (20 h of treatment), the expression of the genes linked to cell adhesion activity and metabolism for cell growth was enhanced. From the present transcriptome analysis, we suggest that Caco-2 cells slow down cell death and turnover of RNA synthesis as an early response to L-92 treatment; at the late stage of treatment, the genes involved in cell proliferation, transcriptional activity, and apoptosis are activated.
Teppei Nakamura,Tatsuhiko Hirota,Katsura Mizushima,Kohji Ohki,Yuji Naito,Naoyuki Yamamoto,Toshikazu Yoshikawa 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.5
Milk-derived peptides, Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP), have angiotensin I–converting enzyme inhibitory activities and blood pressure-lowering effects. We examined the effects of these peptides on the development of atherosclerosis in apolipoprotein E–deficient [apoE(−/−)] mice. For 31 weeks, six-week-old male apoE(−/−) mice received a diet that included one of the following: fermented milk containing both VPP and IPP; casein hydrolysate containing both of these peptides; synthesized VPP; synthesized IPP; enalapril; captopril; or control diet. At the end of feeding, blood biochemistry, aortic atherogenesis, and gene expression by DNA microarray analysis were evaluated. There were no significant changes in the plasma lipid levels and 8-isoprostane, a marker of oxidative stress. The area ratio of intima to media in the aortic arch was significantly lower in the fermented milk, casein hydrolysate, synthesized VPP, enalapril, and captopril groups than in the control group. As is common with diets containing VPP and/or IPP, we observed reductions in mRNA expression of inflammatory cytokines, such as interleukin (IL)-6 and IL-1β, oxidized low-density lipoprotein receptor, and transcription regulators. These results suggest that a continuous intake of VPP and IPP might be beneficial for preventing atherosclerosis caused by hypercholesterolemia.
Yoshichika Onuki,Rikio Settai,Kiyohiro Sugiyama,Tetsuya Takeuchi,Fuminori Honda,Yoshinori Haga,Etsuji Yamamoto,Tatsuma D. Matsuda,Naoyuki Tateiwa,Dai Aoki,Ilya Sheikin,Hisatomo Harima 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
The f-electron system in rare-earth and actinide compounds exhibit a variety of characteristicproperties including heavy fermions and unconventional superconductivity. The Fermi surface propertiesin rare-earth and actinide compounds are clarified by the de Haas-van Alphen experimentson the basis of the results of energy band calculations. The effect of pressure on the electronicstates of CeRhIn5, CeIrSi3, and YbIr2Zn20 is studied in magnetic fields. An electronic instability,including unconventional superconductivity, occurs at 2.4 GPa in CeRhIn5 and 2.6 GPa in CeIrSi3. An abrupt non-linear increase in the magnetization, namely, a metamagnetic behavior, is found inthe heavy fermion compounds, including YbT2Zn20 (T: Co, Rh, Ir). A super-heavy fermion statewith a specific heat coefficient of 10 J/(K2·mol) is realized in YbIr2Zn20 under pressure.