二層構造を持つ混和性流体における過渡的振る舞いへのモデル化によるアプローチ

京都大学新制・課程博士博士(理学)甲第24390号理博第4889号新制||理||1699(附属図書館)京都大学大学院理学研究科数学・数理解析専攻(主査)教授 大木谷 耕司, 教授 並河 良典, 准教授 竹広 真一学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDFA

Magnetic Phase Transition and Magnetization Plateau in Cs2_2CuBr4_4

The crystal structure of Cs$_2$CuBr$_4$ is the same as that of Cs$_2$CuCl$_4$, which has been characterized as a spin-1/2 quasi-two-dimensional frustrated system. The magnetic properties of Cs$_2$CuBr$_4$ were investigated by magnetization and specific heat measurements. The phase transition at zero magnetic field was detected at $T_{\rm N}=1.4$ K. It was observed that the magnetization curve has a plateau at about one-third of the saturation magnetization for magnetic field $H$ parallel to the $b$- and $c$-axes, while no plateau was observed for $H\parallel a$. The field-induced phase transition to the plateau state appears to be of the first order. The mechanism leading to the magnetization plateau is discussed.Comment: 6 pages, 4 figures, 4 eps files, ptptex, will appear in Supplement of Progress in Theoretical Physic

Synthesis of 8β-hydroxy-9(11),13-abietadien-12-one from (+)-dehydroabietylamine and its AhR ligand activity

8β-Hydroxy-9(11), 13-abietadien-12-one (1), an abietane diterpenoid and an aryl hydrocarbon receptor (AhR) ligand, was synthesized in six steps from commercially available (+)-dehydroabietylamine (2). We used the hypervalent iodine catalyst phenyliodine dicarboxylate, a safer alternative to toxic organoselenide reagents, for the oxidative dearomatization of ferruginol (7) to compound 1. Compounds 1 and 2, as well as the synthetic intermediates (compounds 3–7), were evaluated for AhR ligand activity. Only compounds 1 and 7 were active, which suggests that AhR affinity is influenced by the steric environment around the C-18 position of these compounds

Effect of the Combination of Whole-Body Neuromuscular Electrical Stimulation and Voluntary Exercise on Metabolic Responses in Human

PurposeSince neuromuscular electrical stimulation (NMES) can recruit high-threshold motor units and enhance glucose metabolism, the combination of NMES and voluntary low-intensity exercise would induce both anerobic and aerobic energy consumptions and this type of exercise could be more efficient and effective than conventional exercise regimens. We aimed to investigate metabolic responses and muscle fatigue during whole body NMES (WB-NMES), voluntary exercise, and their combination.MethodsThe blood lactate concentration and maximal voluntary contraction were measured before and after specified exercises: WB-NMES (E), voluntary exercise (V), and their combination (VE), and expired gas was sampled during the exercises in thirteen healthy young men. Each exercise was conducted for 15 min and interval between exercise was > 48h.ResultsEnergy expenditure and V˙O2 relative to the body mass during VE were significantly higher than during V and E (p < 0.05). The Respiratory gas exchange ratio (RER) during both E and VE was higher than during V (p < 0.05), and the blood lactate concentration after VE was significantly higher than after V and E (p < 0.05). Although V˙O2 relative to the body mass was 18.6 ± 3.1 ml/min/kg and the metabolic equivalent was 5.31 ± 0.89 Mets, the blood lactate concentration reached 7.5 ± 2.7 mmol/L after VE.ConclusionThese results suggest that the combination of WB-NMES and voluntary exercise can enhance the metabolic response to a level equivalent to high intensity exercise under the net physiological burden of low-middle intensity exercises

Age and gender effect on alexithymia in large, Japanese community and clinical samples: a cross-validation study of the Toronto Alexithymia Scale (TAS-20)

BACKGROUND: The construct validity of alexithymia and its assessment using the 20-item Toronto Alexithymia Scale (TAS-20) in Japan is unknown. Low reliability has been found for the third factor of the TAS-20 in some cultures, and the factor structure for psychosomatic disorder patients has not been adequately investigated. Although alexithymia most likely has certain developmental aspects, this has infrequently been investigated. METHODS: The newly-developed Japanese TAS-20 was administered to a normative sample (n = 2,718; 14–84 y.o.), along with the NEO Five-Factor Inventory (NEO-FFI) for cross validation. Psychosomatic patients (n = 1,924, 12–87 y.o.) were tested to evaluate the factor structure in a clinical sample. College students (n = 196) were used for a test-retest study. Internal reliability and consistency were assessed, and the factorial structure was evaluated using confirmatory and exploratory factor analyses for both the normative and the clinical samples. The correlations between the TAS-20 and the NEO-FFI factor scores were evaluated. Age-related and gender differences in the TAS-20 were explored using analysis of variance in the normative sample. RESULTS: The original three-factor model of the TAS-20 was confirmed to be valid for these Japanese samples, although a 4-factor solution that included negatively keyed items (NKI) as an additional factor was more effective. Significant correlations of the TAS-20 with the NEO-FFI were found, as has been previously reported. Factor analyses of the normative and patient samples showed similar patterns. The TAS-20 total, difficulty in identifying feelings (DIF), and difficulty in describing feelings (DDF) scores were high for teenagers, decreased with age, and from 30s did not change significantly. In contrast, externally oriented thinking (EOT) scores showed an almost linear positive correlation with age. DIF scores were higher for females, while EOT scores were higher for males, without any interaction between gender and age differences. CONCLUSION: The original three-factor concept of the TAS-20 was generally supported for practical use. Age-related differences in TAS-20 scores indicate developmental aspects of alexithymia. Alexithymia is made up of two components with different developmental paths: DIF/DDF and EOT

Video imaging of walking myosin V by high-speed atomic force microscopy

金沢大学理工研究域数物科学系The dynamic behaviour of myosin V molecules translocating along actin filaments has been mainly studied by optical microscopy. The processive hand-over-hand movement coupled with hydrolysis of adenosine triphosphate was thereby demonstrated. However, the protein molecules themselves are invisible in the observations and have therefore been visualized by electron microscopy in the stationary states. The concomitant assessment of structure and dynamics has been unfeasible, a situation prevailing throughout biological research. Here we directly visualize myosin V molecules walking along actin tracks, using high-speed atomic force microscopy. The high-resolution movies not only provide corroborative \u27visual evidence\u27 for previously speculated or demonstrated molecular behaviours, including lever-arm swing, but also reveal more detailed behaviours of the molecules, leading to a comprehensive understanding of the motor mechanism. Our direct and dynamic high-resolution visualization is a powerful new approach to studying the structure and dynamics of biomolecules in action

Supercooling of Homogeneous Liquid Phase of Liquid Metals and Alloys -Poor Supercooling around the Eutectic Composition of Liquid Ni-Nb System

To study the supercooling of many liquid metals with high melting temperatures, the investigation was performed for the cooling curves of electrostatic levitation (ESL) experiments, which had been originally obtained for the measurements of many physical properties. The largest supercooling over the literature values was found for liquid Ru (428 K), Ta (721 K), W (601 K), and Ir (438 K), where temperatures in the parentheses mean the supercooling of respective liquid metals. This indicates the validity of ESL for the supercooling experiments of liquid metals and alloys because of being rather free from the heterogeneous nucleation. This ESL was applied to the study of supercooling of homogeneous liquid phase in the composition range from 29 at% Nb to 71 at% Nb of eutectic Ni-Nb system, whose eutectic point is present at 40.5 at% Nb and 1448 K. The experimental result shows a poor supercooling tendency of homogeneous liquid phase around the eutectic composition in spite of large supercooling far apart from this eutectic composition. This characteristic feature was discussed based on the classical nucleation theory coupled with the knowledge recently found, the existence of concentration fluctuations in the homogeneous liquid phase near the eutectic point

Original Article

Tetrodotoxin, a toxic substance obtained from the globe fish, has been known to paralise the neuromuscular system as well as the central nervous system and recently, it was found to block production of the action potential through its selective inhibition of the sodium-carrying mechanism, but has no effect on the resting potential. In this paper, the effects of tetrodotoxin on the four kinds of skeletal muscle fibers were compared and analysed. Four muscle fibers are tonic and phasic fibers of the extrafusal muscle, and nuclear-bag and nuclear-chain fibers of the intrafusal muscle fibers. The extrafusal muscle is a dynamic source of posture and locomotion, the intrafusal muscle being the regulating source of them. Paralysis of the extrafusal muscle fibers was determined by measuring the decrease in maximum contraction of the soleus (tonic muscle) and tibialis anterior (phasic) produced stimulation of the distal cut end of the ventral root. Paralysis of the intrafusal muscle fibers wasmeasured by a change in the frequency of Group la discharge led from the functionally isolated single filaments of the distal cut end of the dorsal root. By intravenous administration of 4γ/kg tetrodotoxin, paralysis advaces beginning with the intrafusal muscle fibers, and then on to the tonic muscle and phasic muscle fibers. They recover according to the same order. When the intrafusal muscle fiber recovers during an advance in paralysis of the extrafusal muscle, intrafusal muscle fibers contract by the γ-efferent activated by stimulation of the ventral root, and the Group la discharge increases. Frequency of the Group la discharge increases in proportion to muscle extension, therefore the contraction curve of the intrafusal muscle fiber is measured from augmentation of the discharge frequency. Contraction of the intrafusal muscle fibers lasts for several hundred msec, and the curve has two peaks at about 60 msec, and 110 (Fig. 5).It is clear then that the former corresponds to contraction of the nuclear-bag fiber, and the latter to contraction of the nuclearchain fiber