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K. S. Choi M. Yamaguma T. Kodama J. H. Joung M. Takeuchi 《Journal of Loss Prevention in the Process Industries》2001,14(6):512-447
A novel apparatus for testing the minimum ignition energies of flammable dusts is introduced. Unlike the conventional apparatus (the Hartmann tube), this new apparatus employs a vibrating mesh to produce a dust cloud. Using three kinds of powders, namely lycopodium, anthraquinone and polyacrylonitrile, which are designated as the samples for calibration by the International Electrotechnical Commission (IEC, 1994) standards, fundamental characteristics were experimentally investigated. Concerning the minimum ignition energies (MIEs), the new testing apparatus worked well for two samples, lycopodium and polyacrylonitrile. The MIE for anthraquinone, however, was by far larger than the expected value. We concluded that the aggregation of anthraquinone particles is the main cause of the difference and is attributable to both the tribo-charges acquired by the particles when passing through the mesh and the filamentary shape of the crystal. Other essential factors for characterizing the testing apparatus, such as the concentration of dust, the shape and spacing of the sparking electrode system, and the impedance of the sparking circuit are discussed. 相似文献
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Kwang Seok Choi Tomofumi Mogami Teruo Suzuki Sung Chul Kim Mizuki Yamaguma 《Journal of Loss Prevention in the Process Industries》2013,26(1):255-260
As a method to prevent or mitigate electrostatic charge and/or discharges, we have developed a novel AC electrostatic ionizer. In this study, we evaluated experimentally the practical version of the novel AC electrostatic ionizer with a modeling test system and a pneumatic powder transport facility. In addition, electrostatic discharges generated inside a silo while loading polypropylene (PP, 3 mm) granules were observed visually with/without the novel AC ionizer. The specific charge was clearly decreased with the novel AC electrostatic ionizer. The specific charge obtained with the four arranged AC electrostatic ionizers used was approximately one eighth of that without the AC ionizer. The incendiary bulk surface discharges completely died out inside the silo by using the four arranged ionizers. 相似文献
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Kwang Seok Choi Mizuki Yamaguma Atsushi Ohsawa 《Journal of Loss Prevention in the Process Industries》2010,23(2):294-299
Leakage accidents of pressurized flammable liquids often occur in chemical plants. To investigate electrostatic hazards due to liquid leakage, the amounts of electrostatic charge during the leakage were observed. The electric field of the clouds generated by liquid leakage was also examined. Various types of pipeline have been designed in consideration of potential leakage that might lead to accidents during industrial processes. Leakage pressure in the range of 0.1–0.3 MPa was used. With regard to the materials, water and kerosene were used. The results obtained from the experiments show that electrostatic charges depend on leakage parameters, such as the type of liquid, the gasket material between flanges, and the pipeline pressure. In all tests, the amount of the electrostatic charges of water, 0.12–0.83 μC/kg, was larger than that of kerosene, ?0.04 to 0.16 μC/kg. The maximum value of the electric field, generated from the leakage liquid in this study, 40.9 v/cm, is a safe level. No incendiary electrostatic sparks, such as brush and/or spark discharges, were detected in our tests. 相似文献
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Mass balance and long-term fate of PCDD/Fs in a lagoon sediment and paddy soil, Niigata, Japan 总被引:1,自引:0,他引:1
Sakai M Seike N Kobayashi J Kajihara H Takahashi Y 《Environmental pollution (Barking, Essex : 1987)》2008,156(3):760-768
Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in a sediment core and in samples of surface sediment and paddy soil collected from the Toyano lagoon and Kameda basin in Niigata, Japan, were analyzed to elucidate the temporal trends of their concentrations in the lagoon sediment and the relationship between the sediment and the paddy soil. The mass balance of these pollutants was also estimated to determine their long-term fate in surface waters. An analysis by chemical mass balance identified the agrochemicals pentachlorophenol and 2,4,6-trichlorophenyl 4-nitrophenyl ether as the major sources of PCDD/Fs. On the basis of the findings regarding the mass balance in the Kameda basin over the last 40 years, we estimate that more than half the input of PCDD/Fs to the Kameda basin has disappeared. We suggest that the PCDD/Fs that flowed out from the paddy fields have been transferred to the lower basin. 相似文献
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M. Yamaguma K.S. Choi T. Mogami 《Journal of Loss Prevention in the Process Industries》2010,23(5):680-685
While filling a large silo with coarse nonconductive powders, strong electrostatic sparks known as a cone discharge, which can become sufficiently energized to ignite a flammable dust cloud, often occur on the surface of a powder heap. In an attempt to mitigate or eliminate a cone discharge, a long metal rod with a pointed tip or a flat tip was vertically installed in the center of an experimental silo (1.5 m in diameter, 2 m in effective height) with the objective that the static charge might be released by the corona discharges or the surface potential of the powder heap reduced by the electric field reducing effect. The experimental results are summarized as follows:(1) No cone discharges were observed while the silo was being filled with polypropylene pellets when either a pointed tip or a flat-tip rod was installed so that its lower end was located 10 cm above or 30 cm below the heap surface level. A corona discharge that occurred on the pointed tip was shown to be effective to some extent in reducing the charge of the powder heap.(2) Brush discharges were observed near the metal rod and its support. However, we assume that the maximum energy was not high enough to ignite a dust cloud with minimum ignition energy greater than 3 mJ. 相似文献
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Temporal trends and sources of PCDD/Fs, pentachlorophenol and chlornitrofen in paddy field soils along the Yoneshiro River basin, Japan 总被引:1,自引:0,他引:1
Kobayashi J Sakai M Kajihara H Takahashi Y 《Environmental pollution (Barking, Essex : 1987)》2008,156(3):1233-1242
In order to understand the long-term behaviors of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), pentachlorophenol (PCP), and 2,4,6-trichlorophenyl-4′-nitrophenyl ether (chlornitrofen, CNP) in paddy soil, we measured their concentrations in paddy soil samples collected in 1982 and 1984 (1980s) and in 2000 and 2002 (2000s) from the Yoneshiro River basin, Japan. The concentrations of PCP and CNP decreased from the 1980s to the 2000s, whereas the concentrations of PCDD/Fs and their toxic equivalency (WHO2006-TEQ) remained. The major sources of PCDD/Fs in the paddy soil samples were attributed to impurities in PCP and CNP as a result of comparisons of homologue and congener profiles and principal component analysis. Based on the results of comparison of total input and remaining amount, it is estimated that more than 99% of PCP and CNP applied to the paddy fields had disappeared, whereas most of the applied PCDD/Fs and TEQ remained. 相似文献
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Ubiquity of parasporin-1 producers in <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> natural populations of Japan 总被引:1,自引:0,他引:1
Uemori A Maeda M Yasutake K Ohgushi A Kagoshima K Mizuki E Ohba M 《Die Naturwissenschaften》2007,94(1):34-38
Parasporin, a Bacillus thuringiensis parasporal protein, is unique in having a strong cytocidal activity preferential for human cancer cells. In this study, we
characterized parasporin activities associated with three novel geographical isolates of B.
thuringiensis. Parasporal inclusion proteins of the three isolates were highly toxic to human uterus cervix cancer cells (HeLa), but not
to non-cancer uterine smooth muscle cells (UtSMC). Inclusions of the isolates lacked insect toxicity and hemolytic activity
against sheep erythrocytes. Ouchterlony immunodiffusion tests revealed that the proteins of the three isolates are immunologically
closely related to parasporin-1 (Cry31A), but dissimilar to the three other existing parasporin groups. Our results provide
evidence that the parasporin-1-producing organism is a common member in B. thuringiensis populations occurring in natural environments of Japan. 相似文献
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Yuta Endo Atsushi Ohsawa Mizuki Yamaguma 《International journal of occupational safety and ergonomics》2019,25(1):35-39
We investigated the charge generated on bedclothes (cotton and polyester) during bedding exchange with different humidities and the ignitability of an alcohol-based hand sanitizer (72.3 mass% ethanol) due to static spark with different temperatures to identify the hazards of electrostatic shocks and ignitions occurring previously in medical facilities. The results indicated that charging of the polyester bedclothes may induce a human body potential of over about 10?kV, resulting in shocks even at a relative humidity of 50%, and a human body potential of higher than about 8?kV can cause a risk for the ignition of the hand sanitizer. The grounding of human bodies via footwear and flooring, therefore, is essential to avoid such hazards (or to reduce such risks). 相似文献
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