Antibacterial effects of chitosan solution against Legionella pneumophila, Escherichia coli, and Staphylococcus aureus

Chitosan has been shown to have antibacterial activities on the growth of a wide variety of bacteria. Chitosan solution has been sold commercially for use as an antibacterial agent. Chitosan solution contains not only chitosan but also organic acids as solvents and desalted Japan Sea Proper Water (dJSPW). We aimed to clarify whether chitosan solution has antibacterial activity against bacteria invading bath water, and then to explore the causative factor among these ingredients. The antibacterial activity of full-strength chitosan solution and of 10(2)- and 10(4)-fold chitosan solution diluted with purified water was studied against Legionella pneumophila serogroups 1 (L. pneumophila SG1) and 6 (L. pneumophila SG6), Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) for 7 days at 37 degrees C. To clarify the causative factor in the antibacterial activity against E. coli, the antibacterial activities of the full-strength and diluted chitosan solutions for 24 h were examined. L. pneumophila SG1 and SG6, and E. coli could not survive in the chitosan solution or in the 10(2)-fold dilute solution for over a day at 37 degrees C. The cells of S. aureus were found to have decreased more than 2.46 log cfu/ml after 1 day of incubation, not only in the chitosan solutions, but also in phosphate buffer solution as a control. No inhibitory effect of dJSPW on the growth of the bacteria was observed. The antibacterial activity of the chitosan solution was lower compared with those of the organic acids solutions, and it increased with decreasing pH value. We observed the antibacterial activity of chitosan solution against L. pneumophila SG1 and SG6, and E. coli, suggesting it may be due to the decreased pH value derived from organic acids rather than from chitosan itself or dJSPW.     

The development and characteristics of a high-speed EELS mapping system for a dedicated STEM

A new EELS (electron energy loss spectroscopy) real-time elemental mapping system has been developed for a dedicated scanning transmission electron microscope (STEM). The previous two-window-based jump-ratio system has been improved by a three-window-based system. It is shown here that the three-window imaging method has less artificial intensity in elemental maps than the two-window-based method. Using the new three-window system, the dependence of spatial resolution on the energy window width was studied experimentally and also compared with TEM-based EELS. Here it is shown experimentally that the spatial resolution of STEM-based EELS is independent of the energy window width in a range from 10 eV to 60 eV.     

Some compounds separated from depolymerized brown coal

The petroleum ether-soluble fraction of the methylated depolymerized product was fractionated by liquid and gas chromatography and the chemical formulae of nine crystalline substances that were isolated were determined completely or partially. Another two compounds (Figure 6, peaks 18, 23, 0.42%) were also separated and their structure was approximately determined. Seven other peaks (4.11%) were also identified as similar to fractions from liquid chromatography already discussed. Because of over lapping yields in Table 1 and text, the total characterized was only 4.8% of the depoly merized coal, and the total separated about 6.0% (Table 1). From these compounds, suggestions are made for the course of the depolymerization process and for the structure of the coal.     

Characterization of the supermirror hard-x-ray telescope for the InFOCmuS balloon experiment

A hard-x-ray telescope is successfully produced for balloon observations by making use of depth-graded multilayers, or so-called supermirrors, with platinum-carbon (Pt/C) layer pairs. It consists of four quadrant units assembled in an optical configuration with a diameter of 40 cm and a focal length of 8 m. Each quadrant is made of 510 pieces of coaxially and confocally aligned supermirrors that significantly enhance the sensitivity in an energy range of 20-40 keV. The configuration of the telescope is similar to the x-ray telescope onboard Astro-E, but with a longer focal length. The reflectivity of supermirrors is of the order of 40% in the energy range concerned at a grazing angle of 0.2 deg. The effective area of a fully assembled telescope is 50 cm2 at 30 keV. The angular resolution is 2.37 arc min at half-power diameter 8.0 keV. The field of view is 12.6 arc min in the hard-x-ray region, depending somewhat on x-ray energies. We discuss these characteristics, taking into account the figure errors of reflectors and their optical alignment in the telescope assembly. This hard-x-ray telescope is unanimously afforded in the International Focusing Optics Collaboration for muCrab Sensitivity balloon experiment.     

A study of the blast wave from deflagrative explosions

The research reported here is an experimental and theoretical study of the overpressures produced by unconfined vapour-cloud explosions (UVCE) in deflagration. Using the analogy of accidental explosions, the experiments were conducted in the open air using samples of hydrocarbons (propane, n-pentane and n-octane) in the range 0.31 – 313.0 kg by mass. The features observed in the overpressure profiles and their impulses were thoroughly studied by comparison with the results calculated from a simulation model that assumed a propagating flame that was a spherically expanding piston. This model was useful for determining the blast-wave parameters of ideal cases of UVCEs in deflagration. The behaviour of blast waves in dimensionless space was dependent on only the initial flame speed and was independent of mass, that is, it followed a kind of scaling law.     

Tetramer formation from methacrylic acid metal salts in solid state

We have investigated the formation of tetramers of methacrylic acid via the thermal reaction of metallic salts of methacrylic acid salts in the solid state in the temperature range 300°–350°C. N.m.r. and mass spectra and gas chromatography were used in the characterization of the tetramers formed.     

Evaluation on thermal explosion induced by slightly exothermic interface reaction

An asphalt-salt mixture (ASM), which once caused a fire and explosion in a reprocessing plant, was prepared by imitating the real bituminization process of waste on a lab scale to evaluate its actual thermal hazards. Heat flux reaction calorimeters were used to measure the release of heat for the simulated ASM at a constant heating rate and at a constant temperature, respectively. Experimental results show that the reaction in the ASM below about 250 degrees C is a slightly exothermic interface reaction between the asphalt and the salt particles contained in the asphalt, and that the heat release rate increases sharply above about 250 degrees C due to melting of the salt particles. The reaction rates were formulated on the basis of an assumed reaction model, and the kinetic parameters were determined. Using the model with the kinetic parameters, temperature changes with time and drum-radius axes for the ASM-filled drum were numerically simulated assuming a one-dimensional infinite cylinder system, where the drum was being cooled at an ambient temperature of 50 degrees C. The minimum filling temperature, at which the runaway reaction (MFTRR) can occur for the simulated ASM in the drum is about 194 degrees C. Furthermore, a very good linear correlation exists between this MFTRR and the initial radius of salt particles formed in the bituminization product. The critical filling temperature to the runaway reaction is about 162 degrees C for the asphalt-salt mixture, containing zero-size salt particles, filled in the same drum at an ambient temperature of 50 degrees C. Thus, the runaway reaction will never occur in the drum filled with the asphalt-salt mixture under the conditions of the filling temperature below 162 degrees C and a constant ambient temperature of 50 degrees C. As a consequence, the ASM explosion occurred in the reprocessing plant likely was due to a slightly exothermically reaction and self heating.     

钢铁工业中化学分析的溯源性(英文)

按照ISO/IEC17025的规定,钢铁材料的化学分析对于国际单位制(SI)单位或基准不具有直接溯源性。习惯上人们认为,特定的分析方法应通过参考物质建立到基准方法的计量溯源性。标准物质委员会(REMCO)最近定义了基于这种传统概念的有证参考物质(CRM)。本文分析论述了ISO分析技术委员会、国际钢铁工业分析委员会(ICASI)以及为建立钢铁工业中化学分析的计量溯源性而开展的国际能力验证计划等相关工作得到的一些主要结果。     

A Review of Discovery Profiling of PIWI-Interacting RNAs and Their Diverse Functions in Metazoans

PIWI-interacting RNAs (piRNAs) are a class of small non-coding RNAs (sncRNAs) that perform crucial biological functions in metazoans and defend against transposable elements (TEs) in germ lines. Recently, ubiquitously expressed piRNAs were discovered in soma and germ lines using small RNA sequencing (sRNA-seq) in humans and animals, providing new insights into the diverse functions of piRNAs. However, the role of piRNAs has not yet been fully elucidated, and sRNA-seq studies continue to reveal different piRNA activities in the genome. In this review, we summarize a set of simplified processes for piRNA analysis in order to provide a useful guide for researchers to perform piRNA research suitable for their study objectives. These processes can help expand the functional research on piRNAs from previously reported sRNA-seq results in metazoans. Ubiquitously expressed piRNAs have been discovered in the soma and germ lines in Annelida, Cnidaria, Echinodermata, Crustacea, Arthropoda, and Mollusca, but they are limited to germ lines in Chordata. The roles of piRNAs in TE silencing, gene expression regulation, epigenetic regulation, embryonic development, immune response, and associated diseases will continue to be discovered via sRNA-seq.     

In-situ powder neutron diffraction study on the formation process of LaMg2NiH7

The formation process from the intermetallic compound LaMg₂Ni to a complex hydride (deuteride) LaMg₂NiD₇ composed of La³⁺, 2 × Mg²⁺, [NiD₄]^4?, and 3 × D^? was investigated by in-situ powder neutron diffraction under deuterium gas pressure at room temperature. Below 0.001 MPa, small amount of deuterium was initially dissolved in the lattice of LaMg₂Ni forming LaMg₂NiD_0.05 and two new hydride phases (LaMg₂NiD_x1 and LaMg₂NiD_x2) were continuously yielded. Furthermore, LaMg₂NiD_4.6 with NiD_1.9 and NiD_3.3 units and interstitial deuterium atoms was formed prior to appearing of LaMg₂NiD₇. From their Bragg peak positions, the deuterium contents x1, and x2 were inferred as 0.05 < x1 < x2 < 4.6. At approximately 0.001 MPa, LaMg₂NiD₇ started forming. Since the intermediate deuterides had similar metal atomic framework of LaMg₂Ni, we revealed that LaMg₂NiD₇ formation proceeded through multiple deuteride phases with maintaining of the metal atomic framework of LaMg₂Ni.