Control problems in super-articulated mechanical systems

Control of super-articulated mechanical systems (SAMS: controlled mechanical system in which the dimension of the configuration space exceeds the dimension of the control input space) is studied. As a starting point, a graphical characterization of general SAMS is developed in which a so-called control flow diagram (CFD) is constructed to represent the interaction forces among the degrees of freedom of the system; three types of structure, namely, the chain structure, the tree structure and isolated points, are identified; degree of complexity of the system is defined based on the structure of the system. A systematic backstepping type controller design is proposed for systems with a chain structure to achieve global asymptotic stability and trajectory tracking. Such a controller design itself illustrates the sufficient conditions for the existence of smooth feedback control such that the systems with a chain structure can be globally asymptotically stabilized. The connection of the authors' control algorithm with existing results is discussed     

A new neuronal cell protecting substance, lavanduquinocin, produced by Streptomyces viridochromogenes

A new neuronal cell protecting substance, lavanduquinocin was isolated from Streptomyces viridochromogenes 2942-SVS3. It consists of a carbazole skeleton with an ortho quinone function and a cyclolavandulyl moiety. Lavanduquinocin protected neuronal hybridoma N18-RE-105 cells from L-glutamate toxicity with EC50 value 15.5 nm.     

Characterization of a mutation responsible for an alkali-sensitive mutant, 18224, of alkaliphilic Bacillus sp. strain C-125

An alkali-sensitive mutant, 18224, of the alkaliphilic Bacillus sp. strain C-125 was characterized. The nucleotide sequence of the PvuI-NlaIV DNA fragment that recovers the alkaliphily of 18224 has been cloned from the mutant and sequenced. Comparison of the nucleotide sequences of the corresponding regions found a G to A substitution in the mutant. The mutation resulted in an amino acid substitution from 82Gly to Glu of the putative ORF3 product, which consisted a gene cluster of at least four tandemly located open reading frames. The ORF3 product was deduced to be an 112 amino acid polypeptide with hydrophobic properties, which was expressed using an in vitro translation system.     

Measurement on the dielectric properties of acid-doped ice at 9.7GHz

The relative complex dielectric permittivity of acid-doped ice was measured at 9.7 GHz with the standing wave method. The objective of this measurement is to clarify the basic physical properties of ice necessary for the microwave remote sensing of the cryosphere. The acid-doped ice was investigated because acid is one of the major impurities found in snow and ice in the cryosphere. The experimental results show that the complex permittivity increases linearly with concentration of doped acid. Moreover, when the concentration of acid is expressed by molarity, this linear relation is independent of the sort of acid. The complex permittivity of acid-doped ice can be expressed as a function of concentration of acid and temperature definitely. A possible mechanism for enhancing the complex permittivity of acid-doped ice is formation of liquid phase in ice     

Winged bean lipoxygenase—Part 2: Physicochemical properties

Winged bean lipoxygenase (linoleate: oxygen oxidoreductase EC 1.13.11.12) isoenzymes FI and FII were isolated and purified according to the method of Truong et al. (1980).FI and FII were both highly specific for linoleic acid. They exhibited optimal activity at pH 6·0 and 5·8, respectively at 30°C. An activation energy of 4·5 kcal mol^?1 was calculated for this lipoxygenase within the temperature range of 30–50°C.At 0·075% Tween 20, FI and FII had K_m values for linoleic acid of 0·44 and 0·37 × 10^?3M, respectively, compared to 0·4 × 10^?3M for the crude enzyme. Maximal activity was obtained at 1·6 × 10^?3M. Higher levels of Tween 20 inhibited the lipoxygenase activity.Both isoenzymes had identical average molecular weight of 80 000 daltons by gel filtration and SDS gel electrophoresis.FI and FII isoenzymes were strongly inhibited by Hg⁺⁺, Mn⁺⁺, Mg⁺⁺ and Fe⁺⁺⁺ and activated by Zn⁺⁺, Co⁺⁺ and Fe⁺⁺. A difference in the degree of inhibition or activation was observed between FI and FII response. Ca⁺⁺ inhibited both FI and FII but the former was more sensitive to Ca⁺⁺. KCN also inhibited the two isoenzymes.Among the antioxidants tested, butylated hydroxytoluene and butylated hydroxyanisole most effectively inhibited both FI and FII at only 10^?6M. Sulphydryl reagents such as iodoacetamide and dithiothreitol have little effect on the lipoxygenase isoenzyme activity.The lipoxygenase isoenzymes were more stable at neutral pH. The enzyme in the crude extract and especially in situ was more stable to heat treatment.     

Monohole flow test with high-frequency preheating for evaluating flowability of thermosetting compounds

The flow behavior of molding compounds such as phenolics, melamines, and ureas was examined by a monohole flow test in which the compounds were high frequency-preheated up to the test temperature just prior to being put into the monohole mold. The effect of temperature, pressure, and water content on the flowability has been clarified as follows: (1) The relation between log flow rate and reciprocal absolute temperature consists of two straight lines with different slopes, showing dual activation energies for flow above and below an inflection point. The phenomenon suggests the existence of a phase transition in a resin flow. (2) The inflection point shifts to the lower temperature side with an increase of pressure and water content. (3) The influence of water content on the flowability varies largely according to compatibility between resins and water. (4) The temperature dependence of flow rate in a urea compound decreases during storage due to the advancement of condensation.