Synthesis and crystal structure analysis of complex hydride Mg(BH4)(NH2)

Complex hydride Mg(BH₄)(NH₂), which consists of double anion BH₄⁻ and NH₂⁻, was synthesized and the crystal structure was analyzed by synchrotron X-ray diffraction. The mixture sample of Mg(BH₄)₂ + Mg(NH₂)₂ prepared by ball milling was reacted and crystallized to Mg(BH₄)(NH₂) by heating at about 453 K. This crystal phase transforms into amorphous phase above 473 K and subsequently the dehydrogenation begins. The crystal structure of Mg(BH₄)(NH₂) was determined from measurement data at 453 K (chemical formula: Mg_0.94(BH₄)₁(NH₂)_0.88, crystal system: tetragonal, space group: I4₁ (No.80), Z = 8, lattice constants: a = 5.814(1), c = 20.450(4) Å at 453 K). Mg(BH₄)(NH₂) is ionic crystal which the cation (Mg²⁺) and the anions (BH₄⁻ and NH₂⁻) are stacking alternately along the c-axis direction. Two BH₄⁻ and two NH₂⁻ tetrahedrally coordinate around Mg²⁺ ion.     

Nonsolvent coal hydrogenation at short contact time

Yields and properties of products on hydrogenation of Japanese and Australian coals have been studied using an autoclave equipped with a magnedrive device at temperatures of 500–600 °C and hydrogen pressure 4.9–14.7 MPa (gauge) in the absence of solvent. Optimum contact time, at which maximum extraction yield was observed, shifted from 15 s to a few seconds with increasing reaction temperature and hydrogen pressure. The extracts derived from both coals reveal similar structural parameters.     

Improvement of anode oxidation reaction of a fuel cell using ammonium formate with Pt‐Ir catalysis

We have attempted to develop high‐performance and safe fuel cells by using ammonium formate as a solid (powder) fuel. This solid fuel has the potential of safer transportability than liquid fuels such as methanol from the viewpoint of toxicity and flammability. In order to make use of some of the advantages of ammonium formate, we investigated the oxidation characteristics of ammonium formate with respect to a Pt electrode. Cyclic voltammograms indicate that ammonium formate has high oxidation activity with respect to a Pt electrode. We have also found that the oxidation of ammonium formate can be improved by the addition of Ir to Pt catalysts. It is highly likely that ammonium formate will be useful as a solid (powder) fuel for polymer electrolyte membrane (PEM) fuel cells. This new fuel will promote the development of safe fuel cells for PEM. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(4): 45–50, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21043     

Posture Control for Personal Mobility Robot Using Feedback Compensation with Unstable Pole

This paper presents a novel posture control approach using feedback compensation with an unstable pole. For a narrow and small personal mobility robot (PMR), this is needed in order to control its posture for achieving quick turning and high acceleration. However, in the conventional control approach that uses the posture angle as a controlled variable, the zero moment point (ZMP) does not settle to the desired point in the following cases: an unknown disturbance force given to the PMR, a fluctuation in the center of gravity of the PMR, and a change in the conditions between the tires and the road surface. In this paper, a novel control method using feedback compensation with an unstable pole is proposed to achieve the desired ZMP in the steady state. The proposed controller changes the control input for the actuator of posture control to zero in order to achieve the desired posture angle. The effectiveness of the proposed approach is verified through experiments using a prototype of the PMR.     

Effect of poly(vinyl acetate/vinyl alcohol) copolymer with a thiol end group as a steric stabilizer on dispersion polymerization of styrene

In dispersion polymerization of styrene in ethanol, effects of a reactive steric stabilizer, poly(vinyl acetate/vinyl alcohol) copolymer with a thiol end group (P(VAc/VA)-SH), were investigated. In the absence of the thiol end group, the dispersion coagulated at the middle stage of the polymerization, while in the presence of the thiol end group, the polymerization proceeded successfully to result in close to monodisperse particles. The reactive thiol group acts as a site of formation of the block copolymer, that is, polystyrene-b-P(VAc/VA), which is utilized as an effective dispersant. From the measurement on molecular weights during the course of polymerization, two polymerization loci were realized. Addition of butyl methacrylate to styrene affected markedly not only rate of polymerization but also particle size. © 1996 John Wiley & Sons, Inc.     

Theoretical studies on VPI-5. 3. The MS-Q force field for aluminophosphate zeolites

Aluminophosphate zeolite is an artificial material which shows strange hydrophilicity. We have been investigating the reason by quantum mechanics, and found that the hydrophilicity of this zeolite depended on the local geometric deformation, and speculated that the site-specific hydrophilicity might be explained by differences in the stiffness of the local deformation determined by the location with the pore structure. In order to test these ideas, we construct a reliable force field based on the new MS-Q approach developed by Demiralp, Cagin, and Goddard. Our force field well reproduces the experimental structure of VPI-5.     

Ethological data mining: an automata-based approach to extract behavioral units and rules

We propose an efficient automata-based approach to extract behavioral units and rules from continuous sequential data of animal behavior. By introducing novel extensions, we integrate two elemental methods—the N-gram model and Angluin’s machine learning algorithm into an ethological data mining framework. This allows us to obtain the minimized automaton-representation of behavioral rules that accept (or generate) the smallest set of possible behavioral patterns from sequential data of animal behavior. With this method, we demonstrate how the ethological data mining works using real birdsong data; we use the Bengalese finch song and perform experimental evaluations of this method using artificial birdsong data generated by a computer program. These results suggest that our ethological data mining works effectively even for noisy behavioral data by appropriately setting the parameters that we introduce. In addition, we demonstrate a case study using the Bengalese finch song, showing that our method successfully grasps the core structure of the singing behavior such as loops and branches. Yasuki Kakishita and Kazutoshi Sasahara have contributed equally to this work.     

New oxygen-containing compound isolated from coal

A new type of oxygen-containing compound was isolated from benzene extract of Yubari coal. This compound has an aromatic condensed ring structure with the molecular formula C₃₀H₂₀O, and contains oxygen in heterocyclic-ring form as in diphenylene oxide. It may contain three methyl groups; possible formulae are proposed.     

Environmental coupling modulates the attractors of rhythmic coordination.

A simple instance of coupling behavior to the environment is oscillating the hands in pace with metronome beats. This environmental coupling can be weaker (1 beat per cycle) or stronger (2 beats per cycle). The authors examined whether strength of environmental coupling enhanced the stability of in-phase bimanual coordination. Detuning by manipulanda that produced different left and right eigenfrequencies shifted the relative phase angle from 0°, with the size of the shift larger for higher movement frequencies. Stronger environmental coupling was found to decrease this relative-phase shift, with accompanying increase and reduction, respectively, in recurrence quantification measures related to coordination stability and coordination noise. Stronger environmental coupling also increased oscillation amplitude. Results are considered from the perspective of parametric stabilization. (PsycINFO Database Record (c) 2011 APA, all rights reserved)