Nano-motion actuator with large working distance for precise track following

The nano-motion actuator (NMA) had been designed for precise track following on a spin-stand which evaluated read and write performance of a high-density magnetic recording. A required specification of the original NMA was a resonance frequency of over 5 kHz and working distance of over 10 μm. However, according as industrial researches of the perpendicular magnetic recording progress, a phenomenon that is called WATER (Wide Area Track ERasure) should be evaluated on the spin-stand. Since required working distance to evaluate the WATER reaches to over 50 μm, an X–Y stage on the spin-stand was cooperated with the NMA, as usual. However, the piggyback system which combined the X–Y stage with the NMA could not observe the WATER phenomenon continuously on a disk medium. Therefore, a new NMA which had a large working distance of over 50 μm was required. The new NMA was designed and simulated several resonance modes by using 2D or 3D of EFM analysis. The new actuator called as NMA-k501 realized the working distance of 43.3 μm and the resonance frequency of 5.33 kHz with a mechanical damper. As wide servo bandwidth was reached to 2.75 kHz to apply a PID controller, clear and sharp step responses could be showed at a 1 and a 10 nm, respectively. Furthermore, when precise positioning stability was evaluated, the NMA-k501 was positioning within 0.101 nm at 3σ.     

Sum frequency generation microscopy study of cellulose fibers

Sum frequency generation (SFG) microscopy images of cotton cellulose fibers were observed at the infrared wavenumber of ~ 2945 cm(-1) and with a spatial resolution of 2 μm. Domains of different cellulose microfibril bunches were observed and they showed different second-order nonlinear responses. The intensity of the peak of the asymmetric CH(2) stretching mode at 2945 cm(-1) depended strongly on the orientation of the electric fields of the incident visible and infrared light with respect to the cellulose fiber axis. The second-order nonlinear susceptibility arising from the chirality in the cellulose structure was found to be dominant. The SFG of the cross section of the cellulose fiber was relatively weak and showed a different spectrum from that measured from the side of the fiber axis.     

Adaptive notch filter for synchronization and islanding detection using negative‐sequence impedance measurement

Dispersed generation (DG) has been found promising for satisfying the requirements of high power quality in distributed systems. One operation situation, namely, an island, is formed when one or more DG systems and an aggregate of local loads are disconnected from the main grid and remain operational as an islanded entity. Islanding is either due to intentional events, e.g. maintenance outage, or due to unintentional events, such as faults, and their subsequent switching actions. Islanding is usually undesirable because of the potential harm it causes to the existing equipment, human safety, power reliability and quality, etc. Accordingly, anti‐islanding schemes are used to immediately detach a DG system from the feeder after islanding. This paper presents an active method of detecting islanding for DG systems by injecting a small negative voltage into the point of common coupling, and then measuring the negative system impedance. In this study, an adaptive notch filter is introduced as a synchronous part instead of a phase‐locked loop and as a signal processing unit as well. The proposed control strategy allows DG systems to detect properly the occurrence of islanding in a balanced distribution system. Simulation results show the overall system performance including synchronization, power control, and islanding detection capability of the simulated DG system. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Isolation of genes coding for chitin-degrading enzymes in the novel chitinolytic bacterium, Chitiniphilus shinanonensis, and characterization of a gene coding for a family 19 chitinase

Chitiniphilus shinanonensis type strain SAY3(T) is a strongly chitinolytic bacterium, originally isolated from the moat water in Ueda, Japan. To elucidate the chitinolytic activity of this strain, 15 genes (chiA-chiO) coding for putative chitin-degrading enzymes were isolated from a genomic library. Sequence analysis revealed the genes comprised 12 family 18 chitinases, a family 19 chitinase, a family 20 β-N-acetylglucosaminidase, and a polypeptide with a chitin-binding domain but devoid of a catalytic domain. Two operons were detected among the sequences: chiCDEFG and chiLM. The gene coding for the polypeptide (chiN) showed sequence similarity to family 19 chitinases and was successfully expressed in Escherichia coli. ChiN demonstrated a multi-domain structure, composed of the N-terminal, two chitin-binding domains connected by a Pro- and Thr-rich linker, and a family 19 catalytic domain located at the C-terminus. The recombinant protein rChiN catalyzed an endo-type cleavage of N-acetyl-d-glucosamine oligomers, and also degraded insoluble chitin and soluble chitosan (degree of deacetylation of 80%). rChiN exhibited an inhibitory effect on hyphal growth of the fungus Trichoderma reesei. The chitin-binding domains of ChiN likely play an important role in the degradation of insoluble chitin, and are responsible for a growth inhibitory effect on fungi.     

Novel substrate specificity of D-arabinose isomerase from Klebsiella pneumoniae and its application to production of D-altrose from D-psicose

d-Arabinose isomerase from Klebsiella pneumoniae 40bXX was purified 12-fold with a 62.5% yield indicated by its electrophoretic homogeneity. The purified enzyme showed the highest activities toward d-arabinose and l-fucose as substrates at optimum conditions (50 mM glycine-NaOH, pH 9.0, 40 degrees C). The enzyme had a broad range of substrate specificities toward various d/l-aldoses, i.e., d-arabinose, l-fucose, d/l-xylose, d-mannose, d/l-lyxose, l-glucose, d-altrose and d/l-galactose. The equilibrium ratios between d-arabinose and d-ribulose, l-fucose and l-fuculose, d-altrose and d-psicose, and l-galactose and l-tagatose were 90:10, 90:10, 13:87 and 25:75, respectively. Using a combination of the immobilized d-tagatose 3-epimerase and d-arabinose isomerase, we achieved the production of d-altrose from d-fructose in a batch reactor. We successfully produced approximately 12 g of d-altrose from 200 g of d-fructose in a reaction series with an overall yield of 6%. The product obtained was confirmed to be d-altrose by HPLC and (13)C-NMR. To the best of our knowledge, this is the first report on the production of d-altrose from a cheap sugar, d-fructose, using an enzymatic method.     

Energetics of Nitro/Azide Propellants

A new type of double-base propellant which contains GAP was studied in order to elucidate the burning rate characteristics and combustion wave structure. This class of propellants is termed “nitro/azide propellants”. Experimental results revealed that the burning rate and temperature sensitivity are increased when 12.5% DEP is replaced with 12.5% GAP. The reaction rate in the dark zone is increased by the replacement of DEPo with GAP. However, the gas phase structure of NG/NC/GAP propellant is fundamentally the same as that of NG/NC/DEP propellant and the basic chemical reaction mechanism in the gas phase zone remains unchanged for both propellants.