New catalysts for urea formation reactions. II. Catalytic activity of carboxylic acids

Carboxylic acids with weak acidities showed large catalytic activity. For instance, for chlorine-substituted acetic acid the activity increased with decreasing chlorine content. For benzoic acid derivatives, electron acceptor substituents, such as NO₂, CI, and OH, lowered the catalytic activity, while electron donor substituents such as alkyl and alkoxy groups increased it. Detailed study on the cure rate of polyureaurethane, with 2-methyl benzoic acid as a catalyst, showed that pot life (PL) and the minimum demolding time (DT) had a correlation with the catalyst amount [X] represented by the following equation: where A and B are constants. Further, use of appropriate amounts of the catalyst enhanced tensile strength at break for polyureaurethane.     

Quantitative analysis of glycoconjugate precursors of guaiacol in smoke-affected grapes using liquid chromatography–tandem mass spectrometry based stable isotope dilution analysis

Guaiacol has been shown to accumulate in glycoconjugate forms in the fruit and leaves of grapevines following vineyard exposure to bushfire smoke. To investigate the glycosylation of guaiacol in smoke-affected grapes, a quantitative stable isotope dilution analysis method using liquid chromatography-tandem mass spectrometry was developed and validated, using the [²H₄]-labelled analogue of guaiacol β-d-glucopyranoside as internal standard. The method was subsequently applied to the analysis of grapes sampled from grapevines exposed to either bushfire or experimental smoke, enabling compositional comparisons of guaiacol glycoconjugates in smoke-affected grapes from different varieties to be determined, for the first time.     

Zero and First Sound in Normal Fermi Systems

On the basis of a moment method, general solutions of a linearized Boltzmann equation for a normal Fermi system are investigated. In particular, we study the sound velocities and damping rates as functions of the temperature and the coupling constant. In the extreme limits of collisionless and hydrodynamic regimes, eigenfrequency of sound mode obtained from the moment equations reproduces the well-known results of zero sound and first sound. In addition, the moment method can describe crossover between those extreme limits at finite temperatures. Solutions of the moment equations also involve a thermal diffusion mode. From solutions of these equations, we discuss excitation spectra corresponding to the particle-hole continuum as well as collective excitations. We also discuss a collective mode in a weak coupling case.     

Solubilities of NiO and LaNiO3 in Li/Na eutectic carbonate with rare-earth oxide

For the commercial application of molten carbonate fuel cells (MCFCs) under high-pressure operation, the problem of Ni shorting should be solved that is closely related to the solubility of cathode material. In order to improve the MCFC cathode stability, effects of the addition of rare-earth metal oxides to the molten carbonates have been quantitatively investigated. Especially, La₂O₃ addition to the molten carbonate significantly decreased the solubility of NiO. Such low solubility of NiO was caused by effects of both the acid-base equilibrium of molten carbonate and the activity of Ni in solid by the formation of complex oxide. Solubilities of LaNiO₃ and Nd₂NiO₄ were also smaller than that of NiO in molten carbonate as the same reason as that of NiO in the molten carbonates with saturated La₂O₃. Based on the data of solubility, a new parameter was proposed to evaluate the solubility of metal ion in molten carbonates. This parameter concerned with the acid-base equilibrium of melts and the activity of solid for the metal oxide. A linear relationship with the measured solubility of metal oxide in molten carbonates was obtained by this parameter. It would be indicated that the parameter is useful for the prediction of metal oxide solubilities in molten carbonates.     

Observation of superconductivity in granular bi nanowires fabricated by electrodeposition

Bulk rhombohedral Bi at ambient pressure is a well-known semimetal, and its transition to a superconductor has not been observed, at least down to 50 mK. We report that, unlike bulk rhombohedral Bi, granular Bi nanowires with well-defined rhombohedral grains of approximately 10 nm diameter, fabricated by electrochemically depositing Bi into porous polycarbonate membranes at ambient pressure, are superconducting with two transition temperatures, Tc, of 7.2 and 8.3 K. These Tc values coincide with Tc values of the high-pressure phases Bi-III and Bi-V, respectively. Analysis of our structural and transport data indicates that the superconductivity in granular Bi nanowires probably arises from grain boundary areas where there are structural reconstructions between the grains showing a preferred orientation within a small angular distribution.     

Positioning control experiment switching from adaptive nonstationary servo control to force sensorless nonstationary impedance control

The authors have studied on the positioning control of a cart by means of a smooth switching from the servo access control (SAC) for automatic conveyance function to the impedance control (IC) for power-assisting function. The nonstationary optimal control (NOC) method and the force sensorless nonstationary impedance control (FSLIC) method were applied in a previous study. However, NOC requires the offline calculations for generating time-varying feedback gains. This letter shows the experimental result of smooth switching from the adaptive nonstationary servo control (ANSSC) to FSLIC. ANSSC generates the feedback gains online and realizes some adaptive control for parameter variations of a controlled object. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Hazard avoidance for high‐speed mobile robots in rough terrain

Unmanned ground vehicles have important applications in high speed rough terrain scenarios. In these scenarios, unexpected and dangerous situations can occur that require rapid hazard avoidance maneuvers. At high speeds, there is limited time to perform navigation and hazard avoidance calculations based on detailed vehicle and terrain models. This paper presents a method for high speed hazard avoidance based on the “trajectory space,” which is a compact model‐based representation of a robot's dynamic performance limits in rough, natural terrain. Simulation and experimental results on a small gasoline‐powered unmanned ground vehicle demonstrate the method's effectiveness on sloped and rough terrain. © 2006 Wiley Periodicals, Inc.