Synthesis and properties of novel biodegradable polyamides containing α-amino acids

Polyamides are useful biomaterials owing to their biodegradability and good mechanical strength. We have obtained novel polyamides from succinylsarcosine and ethylenediamine by polycondensation in water using 1-ethyl-3-(3-dimethyl-aminopropyl)-carbodiimide (EDC·HCl) and 1-hydroxybenzotriazole. The molecular weight of the obtained polyamides depends on the concentration of the monomers or EDC·HCl, and reached a maximum of over 200,000. The optimal polycondensation temperature was between 10 and 20 °C. We also obtained copolymers of succinylsarcosine and succinylisoleucine by the same method. When the succinylisoleucine content increased, the obtained polyamides showed lower melting points, higher enzymatic degradability, and higher cell adhesion rates. Thermally responsive polyamides containing an elastin-derived pentapeptide, VPGVG, succinylsarcosine, and succinylisoleucine were obtained by the same method. The temperature-dependent precipitation of the polyamide occurred reversibly, and the temperature of precipitation varied from below room temperature to over 80 °C, depending on the ratios of succinylsarcosine and succinylisoleucine.     

Impulse Turbine with 3D Guide Vanes for Wave Energy Conversion

In this study, in order to achieve further improvement of the performance of an impulse turbine with fixed guide vanes for wave energy conversion, the effect of guide vane shape on the performance was investigated by experiment. The investigation was performed by model testing under steady flow condition. As a result, it was found that the efficiency of the turbine with 3D guide vanes are slightly superior to that of the turbine with 2D guide vanes because of the increase of torque by means of 3D guide vane, though pressure drop across the turbine for the 3D case is slightly higher than that for the 2D case.     

The frequency dependent regenerator cold section and hot section positional reversal in a coaxial type thermoacoustic Stirling heat pump

We have constructed and tested two travelling wave thermoacoustic heat pumps using a coaxial configuration with the regenerator positioned in the annulus. We discovered a frequency dependent positional reversal of the cold section and hot section of the regenerator within the test frequency range. By decomposing the measured pressure wave within the annulus, we obtained the positive (w₊) and negative (w₋) propagating travelling waves. It has been revealed the change of frequency is accompanied by a change in magnitudes of w₊ and w₋ which is in part influenced by the presence of travelling wave attenuation through the regenerator. The resulting change of dominant travelling wave on a given end of the regenerator will then change the direction of thermoacoustic heat pumping at that end. This will alter the regenerator temperature distribution and may reverse the cold and hot sections of the regenerator. As the reversal does not require additional moving parts, merely a change in frequency, this feature in coaxial travelling wave devices has tremendous potential for applications which require both heating and cooling operation.     

Decoding of depth and motion in ambiguous binocular perception

We have shown previously that random dots with an interocular time delay (ITD), the time difference of the onset of dots between the two eyes, yield both apparent depth and motion, although depth and velocity are covariant and, thus, ITD is inherently ambiguous. The depth of random dots with ITD was proportional to ITD, suggesting that the visual system assumes a constant velocity of the dots and determines depth on the basis of this constant velocity. We performed psychophysical experiments to investigate whether subjects perceive a constant velocity with a variety of ITDs in random dots aligned along a single vertical line that ensures neither apparent motion nor accidental disparity between the dots. The results showed that subjects perceive a constant velocity for a variety of ITDs with simultaneous perception of depth in proportion to ITD, indicating the priority of depth over velocity in ambiguous binocular perception derived from ITD.     

Comparison of Performances of Turbines for Wave Energy Conversion

The Wells turbine for a wave power generator is a self-rectifying air turbine that is available for an energy conversion in an oscillating water-air column without any rectifying valve. The objective of this paper is to compare the performances of the Wells turbines in which the profile of blade are NACA0020, NACA0015, CA9 and HSIM15-262123-1576 in the small-scale model testing. The running characteristics in the steady flow, the start and running characteristics in the sinusoidal flow and the hysteretic characteristics in the sinusoidal flow were investigated for four kinds of turbine. As a conclusion, the turbine in which the profile of blade is NACA0020 has the best performances among 4 turbines for the running and starting characteristics in the small-scale model testing.     

9-oxo-10(E),12(E)-Octadecadienoic acid derived from tomato is a potent PPAR α agonist to decrease triglyceride accumulation in mouse primary hepatocytes

Scope: Tomato is one of the most common crops worldwide and contains many beneficial compounds that improve abnormalities of lipid metabolism. However, the molecular mechanism underlying the effect of tomato on lipid metabolism is unclear. It has been commonly accepted that peroxisome proliferator‐activated receptor α (PPARα) is one of the most important targets for ameliorating abnormalities of lipid metabolism. Therefore, we focused on the activation of PPARα and attempted to detect active compounds activating PPARα in tomato. Methods and results: To identify such active compounds, we screened fractions of tomato extracts using PPARα luciferase reporter assay. One fraction, rechromatographed‐fraction eluted in 57 min (RF57), significantly increased PPARα reporter activity, in which a single compound is detected by LC/MS analysis. On the basis of LC/MS and NMR analyses, we determined the chemical structure of the active compound in RF57 as 9‐oxo‐10(E),12(E)‐octadecadienoic acid (9‐oxo‐ODA). The RF57 fraction significantly increased the mRNA expression levels of PPARα target genes involved in fatty acid oxidation and O₂ consumption in mouse primary hepatocytes. Furthermore, RF57 inhibited cellular triglyceride accumulation in the hepatocytes. Conclusion: These findings suggest that tomatoes containing 9‐oxo‐ODA that acts on PPARα are valuable for ameliorating abnormalities of lipid metabolism.     

Biomimetic Solid‐Solution Precursors of Metal Carbonate for Nanostructured Metal Oxides: MnO/Co and MnO‐CoO Nanostructures and Their Electrochemical Properties

Biomimetic solid solutions of manganese and cobalt carbonates (MnCO₃–CoCO₃) are used as the precursors for the synthesis of the corresponding metal oxides. The different structures of the metal oxides with porous morphologies, such as pure manganese monoxide (MnO), the solid solution of manganese and cobalt monoxide (MnO–CoO), and the nanocomposite of MnO and metallic cobalt (MnO/Co), are obtained by the appropriate thermal treatments under a reduction atmosphere. The contents of cobalt species can be controlled by the initial cobalt concentration in the MnCO₃–CoCO₃ precursors. The resultant MnO/Co nanocomposites show the enhanced charge–discharge cycle stability and rate performance as an anode material of lithium‐ion battery.     

Measurements of thermal conductivity of 1‐butyl‐3‐methylimidazolium tetrafluoroborate at high pressure

Ionic liquids are salts that are liquid at room temperature. They have attracted considerable attention as new materials. In this study, a transient short‐hot‐wire apparatus was prepared, and the thermal conductivity of 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim] [BF₄]) was measured. The experimental temperatures were from 294 to 334 K, and the pressures were from 0.1 to 20 MPa. It was found that the thermal conductivity of an ionic liquid has a very small temperature and pressure dependence. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(6): 361–372, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20166     

Acute effects of cigarette smoking on global cerebral blood flow in overnight abstinent tobacco smokers.

We examined whether cerebral vascular reactivity to 5% CO2/95% O2 would be a useful, independent measure of effects of tobacco smoking on global cerebral blood flow (gCBF). The acute effects during smoking one's favorite brand of cigarettes were determined after overnight tobacco abstinence. Positron emission tomography was used to quantitatively measure gCBF using H(2)15O in 10 right-handed young-adult male volunteer tobacco smokers. After a 12-hr abstinence, gCBF measurements were repeated six times at 15-min intervals: First baseline, 5% CO2/95% O2 inhalation, first cigarette smoking, second baseline, 5% CO2/95% O2 inhalation, and second cigarette smoking. Surprisingly, no significant change was seen in mean gCBF during smoking compared with baseline. However, the increase in arterial plasma concentration of nicotine correlated inversely with gCBF. Out of 19 smoking sessions, gCBF increased in 7, decreased in 7, and was unchanged in 5 sessions. The gCBF increased during smoking when baseline gCBF was relatively low, whereas gCBF decreased when baseline gCBF was relatively high. Both vascular reactivity and estimated gCBF plus arterial nicotine concentrations were useful measures to predict the changes in measured gCBF. These individual differences result in important bimodal effects of smoking on the brains of different young adult tobacco smokers.