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Fujita M.,Ibaraki University | Ishiwatari Y.,Ibaraki University | Ishiwatari Y.,Industrial Technology Institute of Ibaraki Prefecture | Mishima I.,Center for Environmental Science in Saitama | And 2 more authors.
Water Resources Management | Year: 2014

Water samples collected from a drinking water supply system were assessed for elemental composition (Al, Si, Ca, Mn, Fe and Zn) of suspended particles. Particulate Fe, Mn and Al concentrations were significantly correlated even though their origins are considered to be different. The results of Principal Component Analysis (PCA) and cluster analysis revealed that elemental compositions can vary according to pipe and lining materials and service ages. Differences in concentrations of the particulate elements were calculated between upstream and downstream sites and then subjected to further PCA. In PC1, Fe, Mn and Al exhibited high factor loadings, whereas only Ca was a high contributor for PC2. This implies that ageing-related corrosion and degradation of mortar lining can affect the elemental composition of suspended particles in water distribution systems. We concluded that the elemental composition of suspended particulates can be used to detect ageing pipes in water distribution systems. © 2014 Springer Science+Business Media Dordrecht.


Ishiwatari Y.,Industrial Technology Institute of Ibaraki Prefecture | Ishiwatari Y.,Ibaraki University | Mishima I.,Center for Environmental Science in Saitama | Utsuno N.,Ibaraki Kasumigaura Environmental Science Center | Fujita M.,Ibaraki University
Water Science and Technology: Water Supply | Year: 2013

To develop a method for screening ageing of water supply systems by analysing the supplied water's quality, water samples were collected from a water treatment plant, a delivery pump station, two distribution reservoirs and two feed pipes along a water pipe system. Principal component analysis of the water was conducted. In the first principal component, many elements exhibited high factor loadings, whereas the major contributor for the second principal component was iron (Fe). The unlined steel pipe, which was beyond its working lifetime, had a significantly high Fe content in suspended solids. X-ray absorption fine structure (XAFS) analysis showed differences in the abundance ratios of Fe3O4 and α-FeOOH among the sampling points. It was concluded that the concentration and speciation of Fe in supplied water can be a useful index for detecting the ageing of pipes. Copyright © IWA Publishing 2013.


Kato T.,Ibaraki University | Igarashi S.,Ibaraki University | Ishiwatari Y.,Industrial Technology Institute of Ibaraki Prefecture | Furukawa M.,Perkin Elmer Corporation | Yamaguchi H.,Japan National Institute of Materials Science
Hydrometallurgy | Year: 2013

Separation and concentration of indium from a liquid crystal display (LCD) was conducted using homogeneous liquid-liquid extraction (HoLLE) in order to completely recycle the LCD. First, using 2.40 M hydrochloric acid, 1.52 mg of indium was leached from the LCD of a mobile phone while keeping the amount of leached foreign metals, such as iron and aluminum, as low as possible. The ability to recycle the LCD glass is also expected because arsenic and antimony, which are used as antifoamers for the glass, were separated in the leaching residue. Next, on the basis of the metal leaching results for a mobile phone LCD, HoLLE with Zonyl FSA (CF3(CF2)nCH 2CH2SCH2CH2COOH, n = 6-8, Du Pont Co.) was conducted via the formation of metal-1,10-phenanthroline chelates on a solution formulated to simulate the leachate from a mobile phone LCD. Using this technique, more than 96.7% of the indium was extracted from the simulated leaching solution into the sedimented liquid phase. After phase separation, the volume ratio (Va/Vs) of the aqueous phase (Va) and the sedimented liquid phase (Vs) was 438 (46 ml → 0.105 ml). In addition, the sedimented liquid phase was dropped on a filter and evaluated using X-ray fluorescence analysis. After determination of the elements concentrated into the sedimented liquid phase, the mass concentration of indium in the sedimented liquid phase was estimated to be 10.4 wt%. This result indicated that the mass concentration ratio was 405 because the mass concentration of indium in the mobile phone LCD was 0.0257 wt% on the basis of being determined by heating and leaching with aqua regia. © 2013 Elsevier B.V.


Takahashi M.,Japan National Institute of Advanced Industrial Science and Technology | Ishikawa H.,Industrial Technology Institute of Ibaraki Prefecture | Asano T.,Industrial Technology Institute of Ibaraki Prefecture | Horibe H.,Kanazawa Institute of Technology
Journal of Physical Chemistry C | Year: 2012

In this paper, we describe the use of ozone microbubbles in photoresist removal from silicon wafers. Ozonized water has attracted much attention as an environmental friendly cleaning method in semiconductor manufacturing. However, it would be desirable to enhance the oxidative ability of ozonized water for practical application. The existence of microbubbles in ozonized water has been shown to significantly enhance the photoresist removal rate due to an elevated dissolved ozone concentration (approximately 2.5 times that of ordinary ozone bubbling) and a direct effect of the microbubbles (removal rate is approximately 1.3 times faster than water with the same concentration of dissolved ozone without microbubbles). Additionally, the ozone microbubble solution was able to effectively remove a high-dose ion-implanted photoresist, which is extremely resistant to removal by ozonized water and other wet chemicals because of its amorphous carbon-like layer, or "crust". Electron spin resonance experiments were also performed without the influence of serious metal contamination and indicated the presence of hydroxyl radicals, which are thought to be formed by interaction of ozone with hydroxide ions adsorbed at the gas-water interface upon collapse of the microbubbles. The hydroxyl radicals play an important role in photoresist removal by the ozone microbubble treatment. © 2012 American Chemical Society.


Kubo Y.,Industrial Technology Institute of Ibaraki Prefecture | Rooney A.P.,U.S. Department of Agriculture | Tsukakoshi Y.,Japan National Food Research Institute | Nakagawa R.,Industrial Technology Institute of Ibaraki Prefecture | And 2 more authors.
Applied and Environmental Microbiology | Year: 2011

Spore-forming Bacillus strains that produce extracellular poly-γ-glutamic acid were screened for their application to natto (fermented soybean food) fermentation. Among the 424 strains, including Bacillus subtilis and B. amyloliquefaciens, which we isolated from rice straw, 59 were capable of fermenting natto. Biotin auxotrophism was tightly linked to natto fermentation. A multilocus nucleotide sequence of six genes (rpoB, purH, gyrA, groEL, polC, and 16S rRNA) was used for phylogenetic analysis, and amplified fragment length polymorphism (AFLP) analysis was also conducted on the natto-fermenting strains. The ability to ferment natto was inferred from the two principal components of the AFLP banding pattern, and natto-fermenting strains formed a tight cluster within the B. subtilis subsp. subtilis group. © 2011, American Society for Microbiology.


Mishima I.,Center for Environmental Science in Saitama | Ishiwatari Y.,Industrial Technology Institute of Ibaraki Prefecture | Kato T.,Industrial Technology Institute of Ibaraki Prefecture | Fujita M.,Ibaraki University
Water Science and Technology: Water Supply | Year: 2016

Yellow and red metal oxides are commonly found on deteriorated water pipes and it has been reported that their main component is iron. X-ray absorption fine structure (XAFS) spectroscopy is an effective method which can be used to measure the chemical form of metals. However, when the iron concentration in water samples is extremely low, XAFS measurement and analysis can be difficult due to so much noise in the spectra. In this study, we examined various conditions related to XAFS measurements to analyze the chemical form of iron in water taken from water pipes. To optimize the XAFS measurement conditions, the energy range in pattern fitting was set at 7,100-7,140 eV. Piling up multiple pieces of filter paper was effective for improving the accuracy in the analysis of the XAFS spectra. The XAFS measurement of actual water samples was conducted and a low R factor was obtained from pattern fitting analysis. Differences were observed in the XAFS spectra depending on the chemical form of iron. These results showed that the chemical form of the iron of the actual water samples taken from the water pipes was able to be detected from the XAFS measurement. © 2016 IWA Publishing.


Mendoza-Hernandez O.S.,Nagaoka University of Technology | Ishikawa H.,Nagaoka University of Technology | Ishikawa H.,Industrial Technology Institute of Ibaraki Prefecture | Nishikawa Y.,Nagaoka University of Technology | And 3 more authors.
Electrochimica Acta | Year: 2014

Li-ion insertion/deinsertion reactions of the anode of a Li-ion secondary cell incorporating a reference electrode were analyzed by electrochemical impedance spectroscopy (EIS) at different temperatures and state of charges (SOCs). The cell uses graphitized carbon as anode electroactive material. Impedance spectra fittings were carried out using an equivalent circuit, so that the reaction kinetics could be evaluated accurately. The dependencies of the Li-ion conduction (Rsl1), Li-ion solvation/desolvation (R sl2) and charge transfer (Rct) reactions on the SOC and anode potential were evaluated. The results were compared with a dQ/dE vs. E curve of graphite to analyze how the structural changes of graphite affect the Li-ion insertion process. The charge transfer process was found to be dependent on the SOC and anode potential. On the other hand, Li-ion conduction and Li-ion solvation/desolvation processes did not depend on the SOC and anode potential. © 2014 Elsevier Ltd.


Kawashima H.,University of Tsukuba | Shinotsuka M.,Industrial Technology Institute of Ibaraki Prefecture | Nakano M.,Industrial Technology Institute of Ibaraki Prefecture | Goto H.,University of Tsukuba
Journal of Coatings Technology Research | Year: 2012

Conductive polymers have been studied extensively because of their attractive physical properties, such as conductivity, luminescent performance, and dielectric property. Poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the most employed conductive polymers for applications, such as a buffer layer of organic electroluminescent devices, due to its high conductivity and electrical stability. In this study, we fabricated a conductive paper coated with PEDOT by direct polymerization onto a paper sheet. The conductive paper exhibited the electrical conductivity of 1.8 S/cm. Scanning electron microscopy images of the conductive paper showed two structures: thin polymer membranes attached to cellulose fibers at the surfaces, and thick polymer sheets extended through the void spaces between the fibers in the inner layers. Consequently, strong interactions between the PEDOT and the cellulose fibers enhanced mechanical properties of the conductive paper. Electron probe X-ray microanalysis (EPMA) revealed distribution elemental maps of carbon, oxygen, sulfur, chlorine, and iron on the conductive paper. © ACA and OCCA 2011.


Ishikawa H.,Nagaoka University of Technology | Ishikawa H.,Industrial Technology Institute of Ibaraki Prefecture | Mendoza O.,Nagaoka University of Technology | Sone Y.,Japan Aerospace Exploration Agency | Umeda M.,Nagaoka University of Technology
Journal of Power Sources | Year: 2012

In this study, we analyzed the thermal characteristics of commercial cylindrical lithium-ion cells using an accelerated rate calorimeter (ARC) and by analyzing the electrochemical impedance spectroscopy (EIS) measurements. During the thermal runaway analysis, the cells were tested at different state of charges (SOCs) and the thermal deterioration was determined by monitoring the impedance at 1 kHz and the open circuit voltage as a function of the temperature. The mapping of the thermal runaway was obtained, ant the non-self heating, self-heating and thermal runaway regions were identified at different SOCs. The self-heating and thermal runaway behaviors showed a temperature dependence. In order to clarify the deterioration reaction in the non-self heating region, high temperature storage tests were carried out, storing the cell in the temperature range of 70-100 °C. We estimated the activation energy from the discharge capacities before and after the high temperature storage. In order to determinate the charge/discharge activation energy of the cells, EIS measurements were recorded. Based on our study, the activation energy of the deterioration was about two times greater in magnitude than the activation energy of the charge/discharge. © 2011 Elsevier B.V. All rights reserved.


Mendoza-Hernandez O.S.,Nagaoka University of Technology | Ishikawa H.,Industrial Technology Institute of Ibaraki Prefecture | Nishikawa Y.,Nagaoka University of Technology | Maruyama Y.,Nagaoka University of Technology | Umeda M.,Nagaoka University of Technology
Journal of Power Sources | Year: 2015

The analysis of Li-ion secondary cells under outstanding conditions, as overcharge and high temperatures, is important to determine thermal abuse characteristics of electroactive materials and precise risk assessments on Li-ion cells. In this work, the thermal runaway behavior of LiCoO2 and LiMn2O4 cathode materials were compared at different state of charges (SOCs), including overcharge, by carrying out accelerating rate calorimetry (ARC) measurements using 18650 Li-ion cells. Onset temperatures of selfheating reactions and thermal runaway behavior were identified, and by using these onset points thermal mapping plots were made. We were able to identify non-self-heating, self-heating and thermal runaway regions as a function of state of charge and temperature. The cell using LiMn2O4 cathode material was found to be more thermally stable than the cell using LiCoO2. In parallel with the ARC measurements, the electrochemical behavior of the cells was monitored by measuring the OCV and internal resistance of the cells. The electrochemical behavior of the cells showed a slightly dependency on SOC. © 2015 Elsevier B.V. All rights reserved.

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