Purification, bacteriolytic activity, and specificity of beta-lytic protease from Lysobacter sp. IB-9374

Lysobacter sp. IB-9374, which was isolated from soil as a high lysyl endopeptidase-producing strain (Chohnanet al., FEMS Microbiol. Lett., 213, 13-20, 2002), was found to produce a beta-lytic protease capable of lysing gram-positive bacteria such as Staphylococcus aureus, Microccocuseus, and Bacillus subtilis. The Lysobacter strain secreted the beta-lytic protease into the culture medium at a 2.4-fold higher level than Achromobacter lyticus. The enzyme was highly purified through a series of six steps with a high yield. The enzyme was strongly inhibited by tetraethylene-pentamine and 1,10-phenanthroline. The purified enzyme lysed more efficiently almost all the gram-positive bacteria tested than lysozyme, lysostaphin, and mutanolysin. The enzyme was very similar to Achromobacter beta-lytic protease containing one zinc atom in terms of amino acid composition and N-terminal sequence. The nucleotide sequence revealed that the mature enzyme was composed of 179 amino acid residues with additional 198 amino acids at the amino-terminal end of the enzyme. The deduced amino acid sequence of the mature enzyme coincided with that of the Achromobacter enzyme, although the prepro-region showed a 41% sequence identity with the counterpart. These results indicate that Lysobacter sp. is a useful strain for an efficient large-scale preparation of beta-lytic protease capable of lysing bacteria.     

A spherical aberration-corrected 200 kV TEM

A spherical aberration (Cs)-corrected 200 kV TEM was newly developed. The column of the microscope was extended by 25 cm and the inner yoke of the objective lens was modified to insert some parts of the corrector elements. The corrector has two hexapole elements that play a main role in Cs correction and they are placed at a position equivalent to the coma-free point of the objective lens by using two transfer doublet lenses. The Cs correction was successfully carried out by means of the third-order aberration that was generated in the two extended hexapoles. The Cs can be corrected to the desired value and also can be overcompensated in order to produce a negative Cs, as with the corrected Cs of -23 microm shown in this work. The optical system of the corrector does not produce second- and fourth-order aberrations, and can correct residual aberrations up to the third order. All of the corrector elements are computer-controlled and the third-order aberrations are quite stable after they are properly corrected. The resolution of 0.135 nm was experimentally confirmed by the Young's fringe method. Image simulations of a silicon [110] single crystal were made with various Cs and defocus values to demonstrate the effectiveness of arbitral control of Cs.     

An authorization-based trust model for multiagent systems

In this paper an authorization-based trust model (ABTM) is described which is designed for managing access to services in a semi-open distributed environment. This is called a multiagent-based smart office environment. In this model, "trust" is defined as a set of authorization attributes that are granted by the owner of a service to the user of the service. Central to this model is a trust manager that redelegates authorizations from the service owner to the requesting user, based on access control policies that are specified by role labels which are assigned to a set of agents. The ABTM scheme is different from a centralized scheme, in which authorizations are granted directly by an authority. It is also different from a fully distributed system,where authorizations are granted based solely on the discretion of the owner of the services. The design philosophy is the separation of trust management and trust application to allow efficient management of access control in large-scale and dynamic environment, such as those that exist in multiagent systems.     

Regional noise prediction and management system using remote sensing

Abstract

This paper deals with the prediction and management of regional and environmental noise using remote sensing techniques. Landsat-MSS and -TM data are used to estimate noise pollution by means of a group method of data handling. They estimate ground roughness from the proportion of the area occupied by buildings thus determining the shielding factor of noise propagation on the ground. The noise level predicted by the method presented in this paper showed a satisfactory agreement with that obtained from measurements from various other cases in urban areas.     

Effect of Fe2O3 crystallite size on its mechanochemical reaction with La2O3 to form LaFeO3

Fe₂O₃ powders with different crystallite sizes prepared by heating FeOOH at various temperatures were ground with La₂O₃ powder using a planetary ball mill to investigate the effect of crystallite size on mechanochemical synthesis of LaFeO₃. Fe₂O₃ powder with smaller crystallite size obtained by heating at lower temperature reacts more easily with La₂O₃ than that with larger size. The mechanochemical reaction proceeds with an increase in grinding time. Specific surface area of the LaFeO₃ powder synthesized has a large value of over 11 m²/g. The mechanochemical process can be also applied to synthesize other iron complex oxides with rare earth elements such as Pr, Nd and Sm.     

AC side harmonic and phenomena accompanying DC-injection of utility-interactive PV system

The experiments investigated phenomena related to direct contact between the DC output of a PV array and the AC power from the utility grid. The results show that the DC power flows through the distribution transformers (DC-injection) saturating their magnetic circuits. The saturation of magnetic circuits makes peak currents, incorporating a large portion of even harmonics, flow through the high-voltage side of the distribution transformer, adding the level of harmonic distortion of its exciting current. With the increase of injecting DC-current to the utility grid, peak currents at the primary side of distribution transformer increases the most, and even among the same effective (rms) values, the increase of primary side current is larger than that of the secondary side current.     

A formation of compatible poly(vinyl alcohol)/alumina gel composite and its properties

A formation of poly(vinyl alcohol) (PVA)/alumina gel composite was investigated with a viewpoint of compatibility of the composite. An alumina sol was prepared from aluminium iso-propoxide (Al(iPro)₃). The alkoxide was hydrolyzed and the resultant hydrate was peptized to a clear sol with acetic acid. The composite were transparent in whole content of alumina. The effects of dispersed alumina on the sorption of water and mechanical properties of composite were examined. The composites containing PVA 40–50% are flexible. They are folded in various forms and can be drawn five times the initial length in humid state. The residues obtained by calcination to remove PVA at 600°C keep its original form and transparency.