Hiroshi Machida −respected tephrochronologist, teacher, leader

Professor Emeritus Hiroshi Machida (Hiroshi hereafter) is the leading tephrochronologist of his generation in Japan. Perhaps more than any other geoscientist from Japan, Hiroshi carried the insights and advances of tephra studies and their application in palaeoenvironmental and archaeological applications, landscape processes, and volcanology and hazard analysis, to the outside world through a succession of papers and books written in English and through conference presentations. He has been the ‘international face’ of tephra studies in Japa

Sakurajima-Satsuma (Sz-S) and Noike-Yumugi (N-Ym) tephras: new tephrochronological marker beds for the last deglaciation, southern Kyushu, Japan

Two prominent tephras, Sakurajima-Satsuma (Sz-S) erupted from Sakurajima volcano and Noike-Yumugi (N-Ym) erupted from Kuchierabujima Island, provide new key marker beds for dating and synchronizing palaeoenvironmental and archaeological records in the last deglaciation in southern Japan. These tephras were identified on the basis of glass major-element compositions in two distal areas, a marine core (IMAGES MD98-2195) in the northern part of the East China Sea and on the central part of Tanegashima Island, and related their stratigraphic positions to the marine oxygen isotope-based chronology. In MD98-2195, Sz-S, 0.8 cm in thickness at 9.12 m depth and N-Ym, 3 cm in thickness at 9.30 m depth, are both white, vitric, ash-grade tephras. On Tanegashima Island, Sz-S, 10 cm in thickness and N-Ym, 3 cm in thickness, are stratigraphically constrained by well-characterised marker tephras Kikai-Akahoya (7,300 cal BP) and Aira-Tn (29,000 cal BP). Sz-S is rhyolitic and homogeneous on the basis of glass major-element compositions assayed by electron microprobe. Pumiceous glass shards predominant in distal Sz-S tephra indicate that it derived from pumice fall units that correspond to pumiceous and phreatomagmatic fine ash units constituting proximal Sz-S tephra. N-Ym is rhyolitic and glass major-element analyses reveal compositional diversity between units, suggesting that the lower and middle tephra units dispersed to the east, whereas the upper unit was dispersed north to north-west from the vent. Stratigraphically, Sz-S occurs at around the start of the late-glacial reversal (cooling) in oxygen isotope records of MD98-2195, corresponding to the end of GI-1 and the start of GS-1 in the ice-core events of NGRIP (GICC05), consistent with a terrestrial age of ˜12,800 cal BP. Based on the oxygen isotope stratigraphy, the tephra identified in the core as N-Ym at 9.30 m depth is close to the end of Greenland GI-1 and hence has an age of ˜13,000 cal BP, but on Kuchierabujima Island it has an age based on ¹⁴C assay of charcoal of c. 14,900 cal BP. Although this age discrepancy (14.9 vs 13.0 cal ka) needs resolution, the occurrence in core MD98-2195 of N-Ym shows that it is more widespread than hitherto demonstrated. The widespread distributions and key stratigraphic positions for the two marker tephras indicate that they are thus critical isochrons for precise correlation of palaeoenvironmental changes and prehistoric cultural events during the last deglaciation in southern Kyushu, and for relating such changes and events to the ice-core chronology via the marine oxygen isotope chronostratigraphy

Interactions of microorganisms with rare earth ions and their utilization for separation and environmental technology

In recent years, rare earth elements (REEs) have been widely used in various modern technological devices and the global demand for REE has been increasing. The increased demand for REEs has led to environmental exposure or water pollution from rare earth metal mines and various commercial products. Therefore, the development of a safe technology for the separation and adsorption of REEs is very important from the perspective of green chemistry and environmental pollution. In this review, the application and mechanisms of microorganisms for the removal and extraction of REEs from aqueous solutions are described. In addition, the advantages in using microorganisms for REE adsorption and future studies on this topic are discussed.ArticleAPPLIED MICROBIOLOGY AND BIOTECHNOLOGY. 97(1):1-8 (2013)journal articl

Application of fullerenes-extracted soot modified with ethylenediamine as a novel adsorbent of hexavalent chromium in water

Fullerenes-extracted soot, the by-product of fullerene synthesis, is a carbon composite. The application of this material for water treatment has not yet been developed. Herein, fullerenes-extracted soot in the form of powder containing amino groups was prepared by reacting the soot with ethylenediamine, and was used as an adsorbent of hexavalent chromium [Cr(VI)] for removing Cr(VI) from aqueous solutions; this removal was studied by batch adsorption experiments. The effect of experimental parameters such as the pH, initial Cr(VI) concentration, and agitation time on the adsorption process was investigated. The adsorption of Cr(VI) was highly pH-dependent and the optimal pH for the adsorption process was 3.0. The data of Cr(VI) adsorption by fullerenes-extracted soot modified with ethylenediamine (FES-ED) fit the Langmuir isotherm equation well. The maximum Cr(VI)-uptake capacity of FES-ED was 93 mg g−1. The desorption of Cr(VI) from the adsorbent was also studied. The adsorbed Cr(VI) was eluted with 20 mL of an aqueous solution with pH 12 and the percentage recovery of Cr(VI) was determined as 75%. The adsorption and desorption test using the same FES-ED powder was repeated in triplicate to examine the reusability of the adsorbent. The adsorption was 97% and the desorption was >70% through the adsorption–desorption cycles. The adsorption of methyl orange onto the FES-ED was also examined. The dye was almost quantitatively removed from the aqueous solution by the adsorbent (the initial concentration of methyl orange: 40 μg mL−1; the adsorbent added: 10 mg/40 mL). Thus, we concluded that the FES-ED can be used as a novel adsorbent for removing pollutants from water.ArticleJournal of Environmental Chemical Engineering. 2(2):1191-1198 (2014)journal articl

Antitumor activity of neocarzinostatin, effect on Rauscher leukemia in mice

Neocarzinostatin (NCS), an antibiotic with a high molecular weight, showed an inhibittory effect on Rauscher mouse leukemia. In normal mice, no significant changes were found in peri· pheral blood pictures except a tendency of lymphocytopenia, when O. 05mg/kg/day and O.50mg/kg/day of NCS were injected intraperi. toneally to two groups of mice for three days. On the other hand, peripheral nucleated cells of Rauscher leukemic mice decreased after intraperitoneal administration of NCS in a dose over O.25mg/kg/day for three days. The cells affected by NCS were mainly erythroblasts and smudged cells. Spleens of Rauscher leukemic mice treated with NCS have been reduced in weight, and histological examinations of livers showed a signicant decrease of infiltrating cells. In three groups treated with 0.25mg/kg/day of NCS for seven days, O.25mg/kg/day for three days and O.50mg/kg/day for three days, the.5()% survival time was longer than in the control group. Particularly, the 50% survival time in Rauscher leukemic mice treated with 0.50 mg/kg/day for three days was over twice that of the control group.</p

Glowing gold nanoparticle coating: restoring the lost property from bulk gold

ArticleNanoscale. 11(9): 3786-3793. (2019)journal articl

Application of the powder of porous titanium carbide ceramics to a reusable adsorbent for environmental pollutants

The aim of this study is to investigate the utilization of the powder of porous titanium carbide (TiC) ceramics as a novel adsorbent or a material for solid-phase extraction (SPE). The adsorption and elution of inorganic and organic pollutants, Pb(II), 2,4,6-trichlorophenol (TCP), perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA), to the material were evaluated. The cartridge packed with TiC ceramics powder was used for the extraction test of pollutants. The solution containing pollutants at 1.0 mu g mL(-1) was passed through the TiC cartridge, and the substances were almost quantitatively removed. Furthermore, the pollutants retained in the cartridge were eluted with 3 N HCl for Pb(II) and with methanol for organic pollutants. The recoveries of pollutants were over 80%. In addition, we used the TiC cartridge for the solid-phase extraction of water samples (500 mL each of the distilled water and the river water) by adding pollutants at determined concentrations. Every pollutant was adsorbed almost quantitatively, and eluted by 3 N HCl or methanol. From these results, we concluded that the powder of porous TiC ceramics is a useful reusable adsorbent for the water cleanup and solid-phase extraction.ArticleJOURNAL OF HAZARDOUS MATERIALS. 185(2-3):725-731 (2011)journal articl

Adsorption of rare earth ions onto the cell walls of wild-type and lipoteichoic acid-defective strains of Bacillus subtilis

The aim of this study is to investigate the potential of cell walls of wild-type and lipoteichoic acid-defective strains of Bacillus subtilis 168 to adsorb rare earth ions. Freeze-dried cell powders prepared from both strains were used for the evaluation of adsorption ability for the rare earth ions, namely, La(III), Eu(III), and Tm(III). The rare earth ions were efficiently adsorbed onto powders of both wild-type strain (WT powder) and lipoteichoic acid-defective strain (a dagger LTA powder) at pH 3. The maximum adsorption capacities for Tm(III) by WT and a dagger LTA powders were 43 and 37 mg g(-1), respectively. Removal (in percent) of Tm(III), La(III), and Eu(III) from aqueous solution by WT powder was greater than by a dagger LTA powder. These results indicate that rare earth ions are adsorbed to functional groups, such as phosphate and carboxyl groups, of lipoteichoic acid. We observed coagulated a dagger LTA powder in the removal of rare earth ions (1-20 mg L-1) from aqueous solution. In contrast, sedimentation of WT powder did not occur under the same conditions. This unique feature of a dagger LTA powder may be caused by the difference of the distribution between lipoteichoic acid and wall teichoic acid. It appears that a dagger LTA powder is useful for removal of rare earth ions by adsorption, because aggregation allows for rapid separation of the adsorbent by filtration.ArticleAPPLIED MICROBIOLOGY AND BIOTECHNOLOGY. 97(8):3721-3728 (2013)journal articl

Decomposition of methyl orange using C-60 fullerene adsorbed on silica gel as a photocatalyst via visible-light induced electron transfer

Visible-light induced electron transfer reactions of C60 fullerene adsorbed on silica gel (C60/SiO2 powder) to methyl orange in water have been studied. The C60/SiO2 powder was simply prepared by mixing a toluene solution of the C60 fullerene with silica gel followed by evaporating the toluene. Irradiation by visible light (>420 nm) of the methyl orange aqueous solution (25 μM) in the presence of the C60/SiO2 powder and ascorbic acid resulted in the decomposition of the methyl orange. These results showed that the degradation conversion reached 96% after a 25-min visible light irradiation. The reaction also occurred by the irradiation of sunlight. The reductive products of methyl orange, N,N-dimethyl-p-phenylenediamine and sulfanilic acid, were ascertained and monitored by liquid chromatography/mass spectrometry (LC/MS). The reaction did not occur in the dark and in the absence of C60/SiO2 or ascorbic acid. The possible mechanism of the reaction is discussed. Furthermore, the C60/SiO2 powder was applied to a continuous flow system for the photodecomposition of methyl orange. C60/SiO2 powder was packed in a glass tube. The methyl orange solution was pumped into the glass tube, and the tube was irradiated by visible light or sunlight. The continuous decomposition of methyl orange was achieved by this method.ArticleAPPLIED CATALYSIS B-ENVIRONMENTAL. 166:544-550 (2015)journal articl