Function of Basic Fire Research

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Chitin biodegradation and wound healing in tree bark tissues

Chitin biodegradation and wounded bark tissue healing were demonstrated in several evergreen and deciduous trees by dressing with a sheet of chitin-containing films or sponges. Chitinase activities in the tree bark tissues around the wounds were enhanced by this treatment up to four times those of the untreated wounds. Significant seasonal changes of chitinase activities were observed with the bark and leaf tissues of deciduous trees, but few with those of evergreen trees. A sheet of chitin films implanted or dressed in the tree bark tissues was biodegraded within 4 to 24 weeks after implantation and was assimilated into the wounded bark tissues, resulting in the stimulation of the wounded bark tissue healing.     

Structure of flames propagating through aluminum particles cloud and combustion process of particles

Structure of flames propagating through aluminum particles clouds and combustion processes of the particles have been examined experimentally to understand the fundamental behavior of a metal dust explosion. The combustion process of individual aluminum particles in a flame propagating through the aluminum particles cloud has been recorded by using a high-speed video camera with a microscopic optical system, and analyzed. The flame is shown to be consisted of a preheat zone of about 3 mm thick, followed by a combustion zone of 5–7 mm thick. In the combustion zone, discrete gas phase flames are observed around each aluminum particle. Also an asymmetric flame around a particle is observed, which might be caused by an ejection of aluminum vapor from a crack of oxide shell surrounding the particle.     

Research on leachate recirculation from different types of landfills

Landfills can produce a great amount of leachate containing highly concentrated organic matter. This is especially true for the initial leachate from landfilled municipal solid wastes (MSW) that generally has concentrations of COD(Cr) and BOD(5) up to 80,000 and 50,000mg/L, respectively. The leachate could be disposed by means of recirculating technique, which decomposes the organics through the action of proliferating microorganisms and thereby purifies the leachate, and simultaneously accelerates organic decomposition through water saturation control. Data from experimental results indicated that leachate recirculating could reduce the organic concentration considerably, with a maximum reduction rate of COD(Cr) over 95%; and, using a semi-aerobic process, NH(3)-N concentration of treated leachate could be under 10mg/L. In addition, the organic concentration in MSW decreased greatly.     

Evaluation of mercury contamination using plant leaves and humus as indicators

Plant leaves and humus were collected from three areas with and without mercury emission sources. Mercury in these samples were determined by cold flameless atomic absorption spectrometry. A part of mercury emitted from the source into the atmosphere is absorbed by plant leaves, and move to humus through fallen leaves. Consequentry, plant leaves are able to be used as an indicator for the evaluation of mercury in air at present. Humus is usefull for the evaluation of mercury contamination through the air from the past to present.     

Quantifying the sources of hazardous elements of suspended particulate matter aerosol collected in Yokohama,Japan

We analyzed metals (Mg, Al, Ca, V, Cr, Mn, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Ag, Cd, Cs, Ba, Pb and Bi), water-soluble ions (Na⁺, NH₄⁺, K⁺, Ca²⁺, Cl^?, NO₃^? and SO₄^2?) and carbonaceous mass (EC and OC) in SPM aerosol samples using an ICP-MS, ion chromatograph and CHN corder, respectively. The SPM samples were collected from 1999 to 2005 at two locations (urban site A and industrial site B) of Yokohama, Japan with concentrations in mean and ranges of 34.2 and 19.7–50.3 μg m^?3 and 22.9 and 12.7–35.1 μg m^?3 for the respective location. Source apportionment of SPM aerosol was conducted appropriately for the first time to these locations employing PCA-APCS technique. Major sources of SPM at site A were a) crustal source, b) urban origin, c) undefined, and d) mineral rock. At site B, the sources were predicted as a) urban origin, b) undefined, c) crustal source, and d) secondarily formed aerosol. The tracers and nature of the source related to urban origin at both sites were similar but retaining different source strength. Secondarily formed aerosol was quite unique at site B. However, mineral rock was remarkable at site A.     

Combined biological and photocatalytic treatment for the mineralization of phenol in water

Phenol is degraded by biological treatment, however mineralization requires long time. To decrease the time and operational cost necessary for the mineralization of phenol, an optimum operation condition of the combined biological–photocatalytical treatment was investigated. The mineralization of phenol (50 mg l⁻¹) was conducted in a flow-type biomembrane tank combined with a batch-type TiO₂-suspended photocatalytic reactor. Phenol was degraded biologically to the concentration of 6.8 mg l⁻¹, an effective concentration for further photocatalytic treatment. After the biological treatment, the biotreated phenol was treated photocatalytically to complete the mineralization of phenol. The combined treatment shortened the mineralization time compared to the biological treatment and electric cost compared to the photocatalytic treatment only. The combined treatment may be suitable for a short-time mineralization of phenol in wastewater.     

Growth and reproduction ofCaprella danilevskii (Crustacea: Amphipoda) reared in the laboratory

Caprella danilevskii Czerniavski, an epifaunal amphipod crustacean, was successfully reared for two generations under laboratory conditions. Amphipods were maintained in pairs or fours in a Petri dish. Temperature and photoperiod were maintained at 20°C, and 14 h light: 10 h dark, respectively. Colonies of the diatomCylindrotheca closterium (Ehrenberg) Reumann and Lewin were provided as food source. The red algaGelidium amansii (Lamouroux) Lamouroux was used to provide an attachment substrate for the caprellids. Juveniles that emerged from the brood pouch were described as instar I. Subsequent instars were identified by molts. Juveniles molted successively at 2.5 to 6.5 d intervals. The body length of males at each instar increased exponentially, while that of females followed a sigmoid curve. A different pattern of flagellar segment addition in the antenna I of males and females was revealed. At the age of 20.8 d, females reached instar VII, and produced their first embryos. After 5.1 d, juveniles emerged from the brood pouch. On average, females produced 5.4 clutches successively at 5.0 d intervals. The number of offspring per spawning increased from 6.3 at instar VII to 22.0 at instar XII. The total number of offspring was 69.0 for a female throughout her life span.     

Voltammetric response of ferroceneboronic acid to diol and phenolic compounds as possible pollutants

A voltammetric determination of possible organic pollutants such as diol and phenolic compounds in water was studied using ferroceneboronic acid (FBA) as a redox-active marker. A cyclic voltammogram of FBA exhibited a pair of oxidation and reduction peaks at 230 and 170 mV at pH 7.0, respectively, while another pair of redox peaks was observed in the presence of diol or phenolic compounds tested. The results were rationalized based on the formation of boronate esters of FBA with the added compounds. The changes in the redox peak currents were dependent on the concentration of the additives, suggesting a usefulness of FBA in the electrochemical determination of these compounds in water.