Electromechanical Dynamics Simulations of Superconducting LSM Rocket Launcher System in Attractive-Mode

Further feasibility study on a superconducting linear synchronous motor (LSM) rocket launcher system is presented on the basis of dynamic simulations of electric power, efficiency and power factor as well as the ascending motions of the launcher and rocket. The advantages of attractive-mode operation are found from comparison with repulsive-mode operation. It is made clear that the LSM rocket launcher system, of which the long-stator is divided optimally into 60 sections according to launcher speeds, can obtain high efficiency and power factor

視覚障碍者を対象とした歩行支援システムに関する研究

取得学位：博士(工学)，学位授与番号：博甲第864号，学位授与年月日：平成19年3月22

Coupling of Rotation and Catalysis in F1-ATPase Revealed by Single-Molecule Imaging and Manipulation

SummaryF1-ATPase is a rotary molecular motor that proceeds in 120° steps, each driven by ATP hydrolysis. How the chemical reactions that occur in three catalytic sites are coupled to mechanical rotation is the central question. Here, we show by high-speed imaging of rotation in single molecules of F1 that phosphate release drives the last 40° of the 120° step, and that the 40° rotation accompanies reduction of the affinity for phosphate. We also show, by single-molecule imaging of a fluorescent ATP analog Cy3-ATP while F1 is forced to rotate slowly, that release of Cy3-ADP occurs at ∼240° after it is bound as Cy3-ATP at 0°. This and other results suggest that the affinity for ADP also decreases with rotation, and thus ADP release contributes part of energy for rotation. Together with previous results, the coupling scheme is now basically complete

The Relation of Coffee Consumption to Serum Uric Acid in Japanese Men and Women Aged 49–76 Years

Objective. Few studies have suggested an inverse relation between coffee intake and serum concentrations of uric acid (UA), but none has addressed the relation in men and women separately. We examined the relation between coffee intake and serum UA levels in free-living middle-aged and elderly men and women in Fukuoka, Japan. Methods. Study subjects were derived from the baseline survey of a cohort study on lifestyle-related diseases, and included 11.662 men and women aged 49–76 years; excluded were those with medication for gout and hyperuricemia, use of diuretic drugs, and medical care for cancer or chronic kidney disease. Statistical adjustment was made for body mass index, alcohol use, hypertension, diabetes mellitus, and other factors. Results. There were inverse associations of coffee consumption with serum UA concentrations and hyperuricemia in men regardless of adjustment for covariates. Women showed a statistically significant, but weaker, inverse association between coffee and serum UA levels after allowance for the confounding factors. Conclusion. The findings add to evidence for a protective association between coffee intake and hyperuricemia

Molecular basis for the dosing time-dependency of anti-allodynic effects of gabapentin in a mouse model of neuropathic pain

<p>Abstract</p> <p>Background</p> <p>Neuropathic pain is characterized by hypersensitivity to innocuous stimuli (tactile allodynia) that is nearly always resistant to NSAIDs or even opioids. Gabapentin, a GABA analogue, was originally developed to treat epilepsy. Accumulating clinical evidence supports the effectiveness of this drug for diverse neuropathic pain. In this study, we showed that the anti-allodynic effect of gabapentin was changed by the circadian oscillation in the expression of its target molecule, the calcium channel α2δ-1 subunit.</p> <p>Results</p> <p>Mice were underwent partial sciatic nerve ligation (PSL) to create a model of neuropathic pain. The paw withdrawal threshold (PWT) in PSL mice significantly decreased and fluctuated with a period length about 24 h. The PWT in PSL mice was dose-dependently increased by intraperitoneal injection of gabapentin, but the anti-allodynic effects varied according to its dosing time. The protein levels of α2δ-1 subunit were up-regulated in the DRG of PSL mice, but the protein levels oscillated in a circadian time-dependent manner. The time-dependent oscillation of α2δ-1 subunit protein correlated with fluctuations in the maximal binding capacity of gabapentin. The anti-allodynic effect of gabapentin was attenuated at the times of the day when α2δ-1 subunit protein was abundant.</p> <p>Conclusions</p> <p>These findings suggest that the dosing time-dependent difference in the anti-allodynic effects of gabapentin is attributable to the circadian oscillation of α2δ-1 subunit expression in the DRG and indicate that the optimizing its dosing schedule helps to achieve rational pharmacotherapy for neuropathic pain.</p

Neither Helix in the Coiled Coil Region of the Axle of F1-ATPase Plays a Significant Role in Torque Production

F1-ATPase is an ATP-driven rotary molecular motor in which the central γ-subunit rotates inside the cylinder made of α3β3 subunits. The amino and carboxy termini of the γ-subunit form the axle, an α-helical coiled coil that deeply penetrates the stator cylinder. We previously truncated the axle step by step, starting with the longer carboxy terminus and then cutting both termini at the same levels, resulting in a slower yet considerably powerful rotation. Here we examine the role of each helix by truncating only the carboxy terminus by 25–40 amino-acid residues. Longer truncation impaired the stability of the motor complex severely: 40 deletions failed to yield rotating the complex. Up to 36 deletions, however, the mutants produced an apparent torque at nearly half of the wild-type torque, independent of truncation length. Time-averaged rotary speeds were low because of load-dependent stumbling at 120° intervals, even with saturating ATP. Comparison with our previous work indicates that half the normal torque is produced at the orifice of the stator. The very tip of the carboxy terminus adds the other half, whereas neither helix in the middle of the axle contributes much to torque generation and the rapid progress of catalysis. None of the residues of the entire axle played a specific decisive role in rotation

Influence of Thermodynamic Effect on Blade Load in a Cavitating Inducer

Distribution of the blade load is one of the design parameters for a cavitating inducer. For experimental investigation of the thermodynamic effect on the blade load, we conducted experiments in both cold water and liquid nitrogen. The thermodynamic effect on cavitation notably appears in this cryogenic fluid although it can be disregarded in cold water. In these experiments, the pressure rise along the blade tip was measured. In water, the pressure increased almost linearly from the leading edge to the trailing edge at higher cavitation number. After that, with a decrease of cavitation number, pressure rise occurred only near the trailing edge. On the other hand, in liquid nitrogen, the pressure distribution was similar to that in water at a higher cavitation number, even if the cavitation number as a cavitation parameter decreased. Because the cavitation growth is suppressed by the thermodynamic effect, the distribution of the blade load does not change even at lower cavitation number. By contrast, the pressure distribution in liquid nitrogen has the same tendency as that in water if the cavity length at the blade tip is taken as a cavitation indication. From these results, it was found that the shift of the blade load to the trailing edge depended on the increase of cavity length, and that the distribution of blade load was indicated only by the cavity length independent of the thermodynamic effect

Temperature Dependence of the Rotation and Hydrolysis Activities of F1-ATPase

F1-ATPase, a water-soluble portion of the enzyme ATP synthase, is a rotary molecular motor driven by ATP hydrolysis. To learn how the kinetics of rotation are regulated, we have investigated the rotational characteristics of a thermophilic F1-ATPase over the temperature range 4–50°C by attaching a polystyrene bead (or bead duplex) to the rotor subunit and observing its rotation under a microscope. The apparent rate of ATP binding estimated at low ATP concentrations increased from 1.2 × 106 M−1 s−1 at 4°C to 4.3 × 107 M−1 s−1 at 40°C, whereas the torque estimated at 2 mM ATP remained around 40 pN·nm over 4–50°C. The rotation was stepwise at 4°C, even at the saturating ATP concentration of 2 mM, indicating the presence of a hitherto unresolved rate-limiting reaction that occurs at ATP-waiting angles. We also measured the ATP hydrolysis activity in bulk solution at 4–65°C. F1-ATPase tends to be inactivated by binding ADP tightly. Both the inactivation and reactivation rates were found to rise sharply with temperature, and above 30°C, equilibrium between the active and inactive forms was reached within 2 s, the majority being inactive. Rapid inactivation at high temperatures is consistent with the physiological role of this enzyme, ATP synthesis, in the thermophile