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.     

Development of an In-pipe micro mobile robot using peristalsis motion

Currently, many researchers from various fields are engaged in developing machines that move in a tubular cylinder. Many such machines are being developed for industrial purposes, such as for the examination of ruptures at the joints of gas and water pipes and those caused by cracks. Studies specifically focused on applications to the medical field, such as the realization of machines that can travel through the intestines and blood vessels, have also been reported. In this study, we propose a microscopic moving mechanism that can move in 2–3 mm-diameter blood vessels by peristalsis motion with repeated expansion and contraction using hydraulic pressure, particularly using a physiological saline solution as an acting fluid. Peristalsis motion, observed in earthworms and nematodes, induces shape variation and a shift in the center of gravity, causing extensional waves to propagate and thus achieving movement without damage to the vulnerable inner walls of blood vessels. When this moving mechanism is combined with catheters, we can realize an active catheter that can reach a diseased site by itself. In this study, we created a microrobot with pistonlike hydraulic pressure sources outside both its ends. The microrobot can move back and forth as follows. When the piston pumps, the acting fluid is repeatedly injected into and ejected from the driving body, while the microrobot changes the length and width of its rubber body. The development of our microrobot and the results of its evaluation are reported in this paper.     

Application of beam emission spectroscopy to NBI plasmas of Heliotron J

This paper describes the application of the beam emission spectroscopy (BES) to Heliotron J, having the nonsymmetrical helical-magnetic-axis configuration. The spectral and spatial profile of the beam emission has been estimated by the numerical calculation taking the collisional excitation processes between plasmas (electrons/ions) and beam atoms. Two sets of the sightlines with good spatial resolution are presented. One is the optimized viewing chords which have 20 sightlines and observe the whole plasma region with the spatial resolution Δρ less than ±0.055 using the newly designed viewing port. The other is 15 sightlines from the present viewing port of Heliotron J for the preliminary measurement to discuss the feasibility of the density fluctuation measurement by BES. The beam emission has been measured by a monochromator with a CCD camera. A good consistency has been obtained between the spectral profiles of the beam emission measured by the monochromator and the beam emission spectrum deduced by the model calculation. An avalanche photodiode with an interference filter system was also used to evaluate the signal-to-noise (S/N) ratio of the beam emission in the present experimental setup. The modification of the optical system is being planned to improve the S/N ratio, which will enable us to estimate the density fluctuation in Heliotron J.     

A new, high precision, quick response pressure regulator for active control of pneumatic vibration isolation tables

Pressure regulators are important elements in pneumatic systems. Relief-type precision pressure regulators are commonly used to control the supply pressure to actively controlled pneumatic vibration isolators.Herein, a high precision, quick response pneumatic pressure regulator is proposed. This consists of an isothermal chamber, a servo valve, a pressure sensor, a quick response laminar flow sensor (QFS), and a pressure differential sensor (PD sensor) as developed by the authors. Slight changes of pressure in the chamber can be detected by the PD sensor and are fed back to the servo valve to maintain the pressure at a desired value. The performance of this regulator was confirmed experimentally in comparison with one available commercially. The regulator was then applied to the supply pressure regulation of an actively controlled pneumatic vibration isolation table. The superior performance of the regulator is clearly shown in the experimental results, especially in terms of avoiding effects from upstream or downstream disturbances.     

Quantitative re-examination of Taylor model for FCC polycrystals

The quantitative adequacy of the Taylor model for representing the behaviors of FCC polycrystals is discussed through comparison with crystal plasticity analysis using the homogenization-based finite method. The key element of the crystal plasticity theory is the constitutive relation for single crystals. The most classical way to apply it to polycrystals is the Taylor model. This model assumes that all crystal grains in a crystal aggregate are subjected to the same strain under macroscopically uniform deformation. This assumption provides a solution satisfying the continuity of displacement between crystal grains. The effect and evolution of the crystallographic texture can easily be taken into account. However, the assumption of uniform strain, the main idea in the Taylor model, has never been validated quantitatively. On the other hand, the homogenization-based finite element method can represent arbitrary microscopic deformations, i.e., each crystal grain may have nonuniform deformation, and can provide a material response under more realistic boundary conditions. In this paper, we first determine the appropriate size for the representative volume element (RVE) in the homogenization-based finite element method that can represent the macroscopic polycrystalline behavior of FCC. After that, the polycrystalline behaviors obtained using the Taylor model are compared with those obtained using the homogenization-based finite element method. Finally, the quantitative adequacy of the Taylor model is discussed. It is clarified that the Taylor model is qualitatively consistent with the homogenization-based finite element method and can be used as a practical model of polycrystalline FCC metals for a first-order approximation, although it is not quantitatively reasonable even for FCC metals.     

Bending properties of compressed wood impregnated with?phenolic resin through drilled holes

The effect of drilling on the permeability of Japanese cedar and the bending properties of resin treated compressed wood were examined. Compressed wood was manufactured by impregnating aqueous phenolic resin solutions into the heartwood through drilled holes and polymerizing the impregnated resins using a hot press to maintain the deformation. The compressive deformation was carried out at 150°C for 1 h to one-half of the original specimen thickness. A dye solution permeated the entire specimen when the density of drilled holes exceeded approximately 5000?holes/m². When the compressed wood was manufactured under the drilling condition, the resin type was found to greatly affect the bending strength and the failure mode of the specimens in bending test.     

Low energy ion beam machining of ULE® substrates: Evaluation of surface roughness

In order to apply ion beam figuring (IBF) to final shape correction of the substrates of projection optics for EUVL, ion beam machining characteristics such as high-spatial frequency roughness (HSFR) and mid-spatial frequency surface roughness (MSFR) of ULE^® substrate were investigated. Our previous research confirmed that the surface roughness of the ULE^® machined by Ar⁺ ion beam with energy of 3–10 keV decreases with decreasing the ion beam energy. Therefore, we have conducted our research on ion beam machining of ULE^® substrate by Ar⁺ ion beam with energy from 0.2 to 2 keV. The HSFR and MSFR of the mechanically pre-finished ULE^® substrate were 0.06 and 0.07 nm rms, respectively; whereas, the HSFR and MSFR of the substrate irradiated by Ar⁺ ion beam at energy of 0.3 keV were less than 0.10 and 0.08 nm rms, respectively. The HSFR is the best result among our previous and other current research.     

Identification of Physiological and Toxic Conformations in Aβ42 Aggregates

Aggregation of the 42‐residue amyloid β‐protein (Aβ42) plays a crucial role in the pathogenesis of Alzheimer's disease (AD). Despite numerous structural studies on Aβ aggregates, the relationship between tertiary structure and toxicity remains unclear. Our proline scanning and solid‐state NMR studies suggested that aggregates both of wild‐type Aβ42 and of E22K‐Aβ42 (one of the mutants related to cerebral amyloid angiopathy) contain two conformers: a major one with a turn at positions 25 and 26, and a minor one with a turn at positions 22 and 23. To identify the toxic conformer, the derivative Aβ42‐lactam(22K–23E), in which the side chains at positions 22 and 23 were covalently linked, was synthesized as a minor conformer surrogate, along with Aβ42‐lactam(25K–26E) as a major conformer surrogate. The Aβ42‐lactam(22K–23E) showed stronger aggregation, neurotoxicity, radical generation, and oligomerization than wild‐type Aβ42, whereas in Aβ42‐lactam(25K–26E) were weak. The transition from the physiological conformation with a turn at positions 25 and 26 to the toxic conformation with a turn at positions 22 and 23 might be a key event in the pathogenesis of AD.     

An application of the coulostatic method to corrosion rate measurements

The coulostatic method avoids some of the essential short-comings of the polarization resistance method; in particular, it enables the time to be reduced because in most cases it is sufficient to follow potential decay down to 50% of the original value (this requires less than 0.1 sec). Experiments in 1 n sulfuric acid (with iron) in deionized water, in aerated and deaerated 0.1 m sodium chloride solutions and in an aerated solution containing 0.05 m NaCl + 0.1 m sodium hydrogen carbonate + 0.03 m sodium sulfate (with steel) yield corrosion losses which are well reproducible with the results of other methods, even when surface layers are formed on the metals. Tests with steel 304 in ferric chloride solution and (under crevice corrosion conditions) with steel 403 in 5% NaCl-solution show that the coulostatic method yields reproducible results even in the case of local corrosion with very small amounts of corrosion products being formed. Reliable results are obtained under the conditions of subsurface corrosion, too, so that a rapid screaming of the protective value of various coatings systems becomes feasible.