Publishing type：Research paper (scientific journal)   Publisher：EDP Sciences  

Many accidents have occurred in universities and the accident reports are accumulated in most universities. The information described in the accident reports must be used effectively to prevent a recurrence of the accidents. In this study, we applied text analytics to the description written in 373 accident reports in a university as a case study. Information mining method was adopted for the contents analysis, and 9 factors based on m-SHEL and human error, that is “software”, “hardware”, “environment”, “liveware2”, “management” “slip”, “lapse”, “mistake”, and “violation” were used for morphological analysis for description in report. The factors in each category of accident situation were extracted, and it is suggested that text analytics is one of the most effective methods to analyse the accident reports in universities.

DOI： 10.1051/matecconf/202133310003

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

The present study applies supercritical water oxidation (SCWO) as a pretreatment method for the stable carbon isotope ratio analysis of rice. In this study, three kinds of polished rice with different locations of production were treated by SCWO using a batch-type reactor. At a temperature of 500°C, pressure of 25 MPa, and reaction time of 120 min with an excessive amount of oxygen, more than 99% of the rice-derived organic carbon was converted into carbon dioxide without generating any other C-containing gases. Utilizing TiO as a catalyst, 99.5% of rice-derived organic carbon was selectively converted into CO within 15 min. In each case, the stable carbon isotope ratio of generated CO was successfully obtained using isotope ratio mass spectrometry. The δ C value of CO from the SCWO treatment of rice was compared with that of CO from the catalytic combustion of rice. 2 2 2 2 2 13

DOI： 10.1252/jcej.17we273

Web of Science

Scopus

Language：Japanese  

DOI： 10.11162/daikankyo.19G0201

J-GLOBAL

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publisher：AMER CHEMICAL SOC  

Web of Science

Publisher：SOC BIOSCIENCE BIOENGINEERING JAPAN  

Current research analyzing the effects of water in the field of homogeneous and heterogeneous reactions of organics in sub- and supercritical water are reviewed in this article. Since the physical properties of water (e.g., density, ion product and dielectric constants) can affect the reaction rates and mechanisms of various reactions, understanding the effects that water can have is important in controlling reactions. For homogeneous reactions, the effects of water on oxidation, hydrolysis, aldol condensation, Beckman rearrangement and biomass refining were introduced including recent experimental results up to 100MPa using special pressure-resistance equipment. For heterogeneous reactions, the effects of ion product on acid/base-catalyzed reactions, such as hydrothermal conversion of biomass-related compounds, organic synthesis in the context of bio-refinery, and hydration of olefins were described and how the reaction paths are controlled by the concentration of water and hydrogen ions was summarized. © 2013 The Society for Biotechnology, Japan.

DOI： 10.1016/j.jbiosc.2013.06.011

Web of Science

Scopus

PubMed

Language：Japanese  

DOI： 10.11162/daikankyo.13G1201

J-GLOBAL

Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

An acid-catalyzed dehydration mechanism was investigated for formic acid decomposition through calculations based on density functional theory. In previous experimental investigations, formic acid dehydration in hot compressed water was reported to proceed faster at pressures >30 MPa. Higher concentration of hydrogen ions because of the large ion product of water at high pressure was believed to contribute to the acceleration of the dehydration reaction. In this study, the structures and energies of the transition states and intermediates were determined through calculations based on density functional theory with the B3LYP/6-311+G(2d,p) level of theory. A comparison of their threshold energies indicated that the dehydration proceeded via the protonation of hydroxyl oxygen, and that the acid-catalyzed dehydration was energetically more favored than the water-catalyzed mechanism. These results suggested that the abundant hydrogen ions in hot compressed water at high pressure accelerated the dehydration occurring via an acid-catalyzed formic acid dehydration mechanism. © 2013 Elsevier B.V.

DOI： 10.1016/j.supflu.2013.10.005

Web of Science

Scopus

Language：Japanese  

DOI： 10.11162/daikankyo.13G0703

J-GLOBAL

Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/rpd/ncs224

Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The effects of pressure on formic acid decomposition in sub- and super-critical water from near the critical pressure to extremely high pressures (20-100 MPa) at temperatures of 380 and 400 °C were investigated. Near the critical pressure, the dehydration and decarboxylation rates decreased with increasing pressure. The apparent activation volumes near the critical pressure were high where the isothermal compressibility of water was large, implying that formic acid attracts water molecules better than the transition state does, and that the partial molar volume of the transition state is larger than those of the reactants. At higher pressures, dehydration rate increased with increasing pressure. Comparisons with experimental results for HCl addition at constant pressure suggest that dehydration proceeds via an ionic reaction at high pressures. The pressure may affect formic acid decomposition in supercritical water negatively through solvation effects near the critical pressure, and positively through ionic reactions above 30 MPa. © 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.supflu.2012.07.020

Web of Science

Scopus

Language：Japanese  

DOI： 10.11298/taiki.47.67

J-GLOBAL

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC CHEMICAL ENG JAPAN  

The present study investigates the degradation of soy sauce cake, which is the waste obtained during soy sauce manufacturing, in subcritical water (170-300°C, 10 MPa). In the experiments performed at a constant temperature, the yields of the identified saccharides were lower than the total sugar yield. This suggested that saccharides were recovered mainly as oligomers. We performed a two-step experiment in which the holding temperature was 200°C and 260°C in the first and second steps, respectively. Most of the hemicellulose-derived saccharides were detected in the fraction treated at 200°C, while glucose was detected in the fraction treated at both of the abovementioned temperatures. The total sugar yield in the aforementioned experiment was higher than that obtained in other experiments performed at a constant holding temperature, suggesting that stepwise elevation of the holding temperature facilitates the recovery of valuable compounds from biomass. © 2012 The Society of Chemical Engineers, Japan.

DOI： 10.1252/jcej.10we310

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Scopus

Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Reaction kinetics of methanol oxidation in supercritical water at high pressure condition (420 °C; 34-100 MPa; ρ = 300-660 kg/m ) was investigated. Pseudo-first order rate constant for methanol decomposition increased with increasing water density. Effects of supercritical water on the reaction kinetics were investigated using a detailed chemical kinetics model. Incorporating the effect of diffusion in a reduced model revealed that overall kinetics for SCWO of methanol is not diffusion-limited. Roles of water as a reactant were also investigated. The dependence of sensitivity coefficient for methanol concentration and rate of production of OH radical on water density indicated that a reaction, HO + H O = OH + H O , enhanced the OH radical production and thereby facilitated the decomposition of methanol. It is presumed that concentration of key radicals could be controlled by varying pressure intensively. © 2011 Elsevier B.V. All rights reserved. 3 2 2 2 2

DOI： 10.1016/j.supflu.2011.04.004

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Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN EXPLOSIVES SOC  

In recent years, real-time monitoring devices for explosives are highly needed to safeguard against terrorism. The vacuum ultra-violet single photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS) is expected as one of the attractive options for rapid and sensitive detection of explosives. Especially for 2,3-dimethyl-2,3-dinitrobutane (DMNB) which is explosive taggant species, it is very important to know its mass spectrum pattern for the practical applications. To evaluate the possibility of explosives detection using the VUV-SPI-TOFMS at 10.5 eV ionization energies of typical explosives and explosives-related compounds (ERCs) were estimated by density functional theory (DFT) calculations. From the calculation results it is suggest that most of explosives and ERCs can be ionized with a 10.5 eV photon energy. Though calculated ionization energy of DMNB is 9.38 eV according to a DFT calculation a clear parent peak is not observed in the mass spectrum of DMNB measured by the VUV-SPI-TOFMS at 10.5 eV. Instead many peaks which include the thermal decomposition products are observed in the mass spectrum of DMNB. From the DFT calculations it is shown that a peak at m/z=84 cation which is caused by the elimination of two NO groups can be produced by the ionization at 10.5 eV. 2

Web of Science

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC CHEMICAL ENG JAPAN  

The contribution of ionic reactions to phenol oxidation has been investigated in subcritical and supercritical water. From the experiments conducted at 24.7 MPa, it was found that the phenol conversions at 360°C were slightly higher than that at 400°C. We calculated the concentration of phenolate anion at 24.7 MPa using semiempirical model reported by Sue et al. (2002). The calculated concentration of phenolate anion at 360°C is about seventh order of magnitude higher than that at 400°C because of the high ion product of water at 360°C. The electron transfer (ET) reaction (C H O + O =C H O + O ) was investigated as one of the reasons for the enhancement of phenol oxidation in subcritical water. We estimated the equilibrium constant ofthe ET reaction using density functional theory calculations, which suggests that the ET reaction should be taken into consideration in the region of high ion product of water. We also discussed the dimerization reaction as consumption reactions of phenoxy radical and other reactions involving inorganic ion species such as O , OH and HO . When phenoxy radical and O are produced effectively, these reactions could be more favorable id subcritical water than in supercritical water. From these discussions, phenol oxidation in subcritical water could be enhanced by the ionic reaction mechanism because of a high ion product of water. Copyright © 2007 The Society of Chemical Engineers, Japan. 6 5 2 6 5 2 2 2 2 - - - - - - -

DOI： 10.1252/jcej.40.556

Web of Science

Scopus

Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Reaction kinetics of methanol and ethanol oxidation in supercritical water at 520-530 °C and 24.7 MPa were investigated both experimentally and by computational simulation. Furthermore, studies were performed on the oxidation of the two alcohols in binary mixtures. For the methanol system, experimental data showed that the methanol conversion decreased with increasing initial methanol concentration in the low concentration range (from 6.48 × 10 to 3.94 × 10 mol/l), whereas the conversion increased for initial concentrations in the high concentration range (from 2.23 × 10 to 1.55 × 10 mol/l). Kinetic analyses based on the elementary reaction model showed that production of OH from the reaction of H O with HO seemed to play an important role at the low methanol concentrations and that the characteristic dependence of methanol conversion on initial methanol concentration was due to the very high concentration of H O in supercritical water oxidation of methanol. For the binary system, it was found that methanol conversion was accelerated by ethanol addition whereas ethanol oxidation was slightly retarded by the presence of methanol. Calculation with an elementary reaction model could reproduce the phenomenological mutual effects of alcohols with respect to reaction rates, and it was found that the acceleration/retardation effect of conversions could be well characterized by the time profile of OH radical, rather than HO radical. © 2006 Elsevier B.V. All rights reserved. -6 -5 -4 -3 2 2 2 2

DOI： 10.1016/j.supflu.2006.04.006

Web of Science

Scopus

Publishing type：Research paper (scientific journal)  

For the on-site treatment of laboratory waste, we have been developing a compact-sized reaction system for the treatment of laboratory wastewater using supercritical water oxidation (SCWO) technology. Pharmaceutical laboratory wastewater is one of the most difficult wastewaters to treat because of its high concentration of halogenated organic compounds. We proposed a new cascade process in which two reactors are consecutively combined, carrying out hydrolysis in the first reactor followed by SCWO in the second reactor, for the complete removal of halogenated organic compounds. Dichloromethane was chosen as a representative model of chlorinated compounds. There have been many previous studies on the hydrolysis of dichloromethane, which results in the coproduction of formaldehyde and HCl. However, there has been less investigation on the kinetics of formaldehyde oxidation in supercritical water. In this study, we focus on the oxidation of formaldehyde in supercritical water with and without a catalyst. As a result, formaldehyde can be completely decomposed at 400 degrees C and 25 MPa within a very short contact time in a heterogeneous system with a MnO(2) catalyst.

Scopus

PubMed

Publishing type：Research paper (scientific journal)  

Supercritical water oxidation (SCWO) is a reaction in which organics in an aqueous solution can be oxidized by O2 to CO2 and H2O at a very high reaction rate. In 2003, The University of Tokyo constructed a facility for the SCWO process, the capacity of which is approximately 20 kl/year, for the purpose of treating organic laboratory waste. Through the operation of this facility, we have demonstrated that most of the organics in laboratory waste including halogenated organic compounds can be successfully treated without the formation of dioxines, suggesting that SCWO is useful as an alternative technology to the conventional incineration process.

Scopus

PubMed

Publishing type：Research paper (international conference proceedings)  

Supercritical Water Oxidation (SCWO) is a promising technology for waste treatment process in which aqueous organic waste can be rapidly and completely decomposed. Experiments of SCWO of mixtures were conducted, and their kinetics and mechanisms were analyzed by simulation based on elementary reaction model. In the case of alcohol mixtures, methanol oxidation was accelerated in the presence of ethanol or 1-propanol and the extent of acceleration became larger as increasing the ratio of addition. On the other hand, the decomposition rate of ethanol or 1-propanol was retarded in the presence of methanol, but the extent of smaller than the effect to methanol. In the case of phenol/alcohol mixture, the phenol conversion was not affected by the alcohol existence, but the decomposition rate of alcohol was retarded. In the presence of alcohol, the production rate of dimers was retarded. These results suggested that the alcohols could be a good race-enhancer in SCWO. This is an abstract of a paper presented at the 7th World Congress of Chemical Engineering (Glasgow, Scotland 7/10-14/2005).

Scopus

Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Event date： 2011.11

Presentation type：Symposium, workshop panel (nominated)  

Country：Japan  

Event date： 2007.3

Presentation type：Oral presentation (invited, special)  

Venue：Beijing   Country：China  

Type：Academic society, research group, etc.