Isolation and characterization of a novel gene encoding alpha-L-arabinofuranosidase from Aspergillus oryzae

We cloned and characterized a novel gene (abfA) encoding alpha-L-arabinofuranosidase (alpha-L-AFase) from Aspergillus oryzae. One clone homologous to the alpha-L-AFase gene of Thermotoga maritima was found in an expressed sequence tag (EST) library of A. oryzae and a corresponding gene was isolated. Molecular analysis showed that the abfA gene carried six exons interrupted by five introns and had an open reading frame encoding 481 amino acid residues. The amino acid sequence similarity at active sites to the alpha-L-AFases from other organisms indicated that the alpha-L-AFase encoded by abfA was classified as a family 51 glycoside hydrolase. When the abfA was overexpressed in the homologous hyperexpression system of A. oryzae, a large amount of alpha-L-AFase was produced as intracellular protein. The apparent molecular mass of the purified enzyme was estimated to be 228,000 by gel filtration and that of its subunit as 55,000 by SDS-PAGE, suggesting that the enzyme is a tetramer. The enzyme hydrolyzed p-nitrophenyl-alpha-L-arabinofuranoside but not other p-nitrophenyl glycosides. These results demonstrated that the abfA gene encodes a functional alpha-L-AFase.     

A simulation model for compartment fires

From the standpoint that the strict estimation of heat released in an enclosure is important to simulate enclosure fires, a new mathematical model involving the combustion efficiency, the temperature dependence of heat capacities, and the composition of burnt gas has been developed. The calculated results are in good agreement with a few experimental results for enclosure fires having different fuel areas and compartment sizes.     

A stochastic method to predict the consequence of arbitrary forms of spike-timing-dependent plasticity

Synapses in various neural preparations exhibit spike-timing-dependent plasticity (STDP) with a variety of learning window functions. The window functions determine the magnitude and the polarity of synaptic change according to the time difference of pre- and postsynaptic spikes. Numerical experiments revealed that STDP learning with a single-exponential window function resulted in a bimodal distribution of synaptic conductances as a consequence of competition between synapses. A slightly modified window function, however, resulted in a unimodal distribution rather than a bimodal distribution. Since various window functions have been observed in neural preparations, we develop a rigorous mathematical method to calculate the conductance distribution for any given window function. Our method is based on the Fokker-Planck equation to determine the conductance distribution and on the Ornstein-Uhlenbeck process to characterize the membrane potential fluctuations. Demonstrating that our method reproduces the known quantitative results of STDP learning, we apply the method to the type of STDP learning found recently in the CA1 region of the rat hippocampus. We find that this learning can result in nearly optimized competition between synapses. Meanwhile, we find that the type of STDP learning found in the cerebellum-like structure of electric fish can result in all-or-none synapses: either all the synaptic conductances are maximized, or none of them becomes significantly large. Our method also determines the window function that optimizes synaptic competition.     

Electron holographic 3-D nano-analysis of Au/TiO2 catalyst at interface

Three-dimensional (3-D) nanostructures of gold catalysts supported on TiO2 were analysed by electron holography and high-resolution electron microscopy. The contact angle of the gold particle on TiO2 tended to be >90 degrees in the case of gold particles with a size (height) of >4 nm and it tended to be <90 degrees for gold particles with a height of <2 nm. The change in morphology increases the perimeter at the Au/TiO2 interface as the particle size decreases. This change in 3-D structure should be attributed to a change in electronic structure at the interface. It was found that electron holography enabled 3-D analysis at the atomic level and was effective for analysing nanostructured particles.     

A Gait Phase Measurement System Using Treadmill Motor Current

The article describes the development of a gait phase time-based split-belt treadmill measurement system. Conventional methods of measuring gait phase, such as the foot switch and force plate, require significant preparation and are costly. In this article, we propose a simple, cheap, and accurate gait phase measurement system that utilizes only the treadmill motor current value. Comparison of this algorithm with conventional methods reveals that the proposed algorithm is as accurate as the foot switch. Moreover, the proposed algorithm can estimate stance phase within a 0.2?s error of the measured value of the force plate in most cases (four out of five healthy subjects). This accuracy is higher than that of the foot switch which is widely used in the clinical field.     

Multi-rigid-body dynamics and online model predictive control for transformable multi-links aerial robot*

Transformable multi-links aerial robots have great potentials in application relying on the transformable features to change its shape during the flight. Compared to traditional quadrotor robots, transformable multi-links robots are equipped with servo motor between links. To simplify the non-linear dynamic system, the previous work restricts the robot to transform in very slow speed so that the robot could be approximated as a quadrotor robot at each time point. However, tradeoff comes as the dynamic performance is given up. In this paper, we come up with a new framework combining of computationally efficient non-linear model predictive controller and motion primitive to optimize thrust force and joints trajectory of the multi-links aerial robot. Finally, we verify our framework with fast transformation motions and table tennis task which requires dynamic performance.     

Integration of photocatalysis and membrane distillation for removal of mono- and poly-azo dyes from water

The paper reports investigations on the application of anatase-phase TiO₂ for the removal of azo dyes in a hybrid system coupling photocatalysis with direct contact membrane distillation (DCMD, MD). The process was conducted in a laboratory-scale installation equipped with a PP capillary module. The influence of reaction temperature and initial concentration of azo dyes on the effectiveness of their photodegradation was especially investigated. Two mono-azo dyes: Acid Red 18 (AR18) and Acid Yellow 36 (AY36) and one poly-azo dye, Direct Green 99 (DG99) were applied as model compounds. The increase of the reaction temperature from 313 to 333 K resulted in an improvement of the efficiency of photodecomposition of the dyes, as was found on the basis of changes of their masses in the feed solution. The comparison of the results obtained during photocatalysis alone and hybrid photocatalysis-MD process revealed that the reduction of feed volume in MD did not affect the photodegradation rate of the azo dyes. An improvement of the effectiveness of the degradation of dyes was obtained by an application of solutions with lower initial concentration (10 instead of 30 mg/dm³). Regardless of the process parameters applied, the product (distillate) was almost pure water with conductivity lower than 0.3 mS/m and pH above 5.2.     

TiO2 thin films using organic liquid materials prepared by Hot-Wire CVD method

TiO₂ thin films prepared by Hot-Wire CVD method have been studied as a protecting material of transparent conducting oxide (TCO) against atomic hydrogen exposures for the fabrications of Si thin film solar cells. It was found that electrical conductivity of the films at room temperature reached a value of 0.4 S/cm. This value is 2-3 orders of magnitude higher than that of TiO₂ films prepared by RF magnetron sputtering and electron-beam evaporation methods in our previous works. The conductivity improvement seems to be partly due to the enlargement of TiO₂ crystallites.     

Reductive activation of dioxygen: A new concept for the catalytic oxidation

Transition metal–dioxygen complexes, which have been studied intensively in relevance to the active species of oxygenation with dioxygen molecule, are classified according to the extent of electron transfer from the metal center(s) to the O₂ ligand. A new O₂-activation method via a higher valent bis(μ-oxo) dimetal species resulting from extensive electron transfer is proposed on the basis of the results of our bioinorganic studies on the dioxygen complexes supported by the hydrotris(3,5-diisopropylpyrazolyl)borate ligand (Tp^iPr).     

Crystal orientation of poly(?-caprolactone) blocks confined in crystallized polyethylene lamellar morphology of poly(?-caprolactone)-block-polyethylene copolymers

The crystal orientation of poly(?-caprolactone) (PCL) blocks in PCL-block-polyethylene (PE) copolymers has been investigated using two-dimensional small-angle X-ray scattering (2D-SAXS) and 2D wide-angle X-ray diffraction (2D-WAXD) as a function of crystallization temperature T_c and thickness of PCL layers d_PCL. The PCL blocks were spatially confined in the solid lamellar morphology formed by the crystallization of PE blocks (PE lamellar morphology), an alternating structure of crystallized PE lamellae and amorphous PCL layers. This confinement is expected to be intermediate between hard confinement by glassy lamellar microdomains and soft confinement by rubbery ones, because the crystallized PE lamellae consist of hard PE crystals covered with amorphous (or soft) PE blocks. The 2D-SAXS results showed uniaxial orientation of the PE lamellar morphology after applying the rotational shear to the sample. Therefore, it was possible to investigate crystal orientation of PCL blocks within the oriented PE lamellar morphology. The 2D-WAXD results revealed that the c axis of PCL crystals (i.e., stem direction of PCL chains) was parallel to the lamellar surface normal irrespective of T_c when 16.5 nm ≥ d_PCL ≥ 10.7 nm. However, it changed significantly with changing T_c when d_PCL = 8.8 nm; the c axis was perpendicular to the lamellar surface normal at 45 °C ≥ T_c ≥ 25 °C while it was almost random at 20 °C ≥ T_c ≥ 0 °C. These results suggest that the PE lamellar morphology plays a similar role to glassy lamellar microdomains regarding spatial confinement against subsequent PCL crystallization.