Satoru Nakashima | Kansai University (original) (raw)

Papers by Satoru Nakashima

Geophysical Journal International, 2017

Electrical conductance G at 100 kHz of Berea sandstone initially saturated with varying NaCl conc... more Electrical conductance G at 100 kHz of Berea sandstone initially saturated with varying NaCl concentrations was measured by an impedance meter at decreasing water saturation. The obtained conductance G values can be well simulated by the model equation composed of conductance of bulk pore water and that of mineral surfaces by introducing both tortuosities of bulk pore water τ b and mineral surfaces τ s. The surface conductivity s = 2.1 × 10 −10 S and the tortuosity of mineral surfaces τ s = 2.6 in this equation can be valid for most of the data at varying water saturation except for the lowest water saturation (S w = 0.05). The tortuosity of pore water τ b increased from 1.7 at S w = 1.0 to 15 at S w = 0.05 with a power law relationship. The present electrical conduction model with double tortuosities of bulk pore water τ b and mineral surfaces τ s can be considered as an alternative expression of the combined Archie's first and second laws in terms of tortuosities and would be useful for describing conductance of electrolyte containing partially saturated rocks including very low water saturation.

Journal of remote sensing, 2003

RGB values from CCD cameras are device-dependent, and are not able to be simply converted into in... more RGB values from CCD cameras are device-dependent, and are not able to be simply converted into international color standard CIE XYZ (and L*a*b*) values. We have developed a calibration method from these RGB values to CIE L*a*b* values by using a standard color sample set. We achieved the accuracy of ƒ¢E*ab 2.23 (standard deviation of error•~2.5) by applying a couple of calculation techniques to the calibration. First, accuracies of X, Y and Z estimations in the lower range are enhanced, while those in the higher are diminished. In the converting equations from XYZ to L*a*b*, XYZ values are powered by third. Hence, estimation error in low XYZ region reduces L*a*b* estimation accuracy more effectively. The second method is interactive modifications of X and Z values. Values of a* and b* is derived by Y and X, and Y and Z, respectively. For example, a combination of larger estimation error in Y and smaller estimation error of Z yields very high deviation of b*. To avoid this, we modifi...

Journal of the Mineralogical Society of Japan, 1990

Origins of Life and Evolution of Biospheres, 2016

It has long been suggested that mineral surfaces played an important role in peptide bond formati... more It has long been suggested that mineral surfaces played an important role in peptide bond formation on the primitive Earth. However, it remains unclear which mineral species was key to the prebiotic processes. This is because great discrepancies exist among the reported catalytic efficiencies of minerals for amino acid polymerizations, owing to mutually different experimental conditions. This study examined polymerization of glycine (Gly) on nine oxide minerals (amorphous silica, quartz, α-alumina and γ-alumina, anatase, rutile, hematite, magnetite, and forsterite) using identical preparation, heating, and analytical procedures. Results showed that a rutile surface is the most effective site for Gly polymerization in terms of both amounts and lengths of Gly polymers synthesized. The catalytic efficiency decreased as rutile > anatase > γ-alumina > forsterite > αalumina > magnetite > hematite > quartz > amorphous silica. Based on reported molecularlevel information for adsorption of Gly on these minerals, polymerization activation was inferred to have arisen from deprotonation of the NH 3 + group of adsorbed Gly to the nucleophilic NH 2 group, and from withdrawal of electron density from the carboxyl carbon to the surface metal ions. The orientation of adsorbed Gly on minerals is also a factor influencing the Gly reactivity. The examination of Glymineral interactions under identical experimental conditions has enabled the direct Orig Life Evol Biosph

We have proposed a novel astrobiological mission "Tanpopo" on the International Space S... more We have proposed a novel astrobiological mission "Tanpopo" on the International Space Station. The mission has six sub-themes. In the present paper, we will present scientific objectives of two sub-themes: (1) Capture of cosmic dusts to analyze organic compounds of extraterrestrial origins, and (2) Exposure of organic compounds in actual space environments. Organic compounds found in such extraterrestrial bodies as comets and meteorites seem to have been originally formed in dense clouds before formation of the solar system. When frozen mixtures of simple molecules found in ice mantles of interstellar dusts with high-energy particles from accelerators, complex organic compounds with molecular weights of thousands were formed. They gave amino acids after acid-hydrolysis. It strongly suggested that complex organic compounds containing precursor of bioorganic compounds were formed in interstellar environments and that they were incorporated in such solar system small bodies a...

Astrobiology" is a novel interdisciplinary field defined as origins, evolution, distribution... more Astrobiology" is a novel interdisciplinary field defined as origins, evolution, distribution and destiny of life in the Earth and elsewhere in space. We organized the working group "Astrobiology Experiments in Earth Orbit" and have been discussed possible subjects of astrobiological experiments in Earth orbit since 2004. In 2006, we picked up one of the subjects, and it was proposed to JAXA as the "Tanpopo mission". In order to study origins and distribution of life in space, both in earth orbit and in planetary bodies, it is necessary to develop novel sensitive techniques to detect and characterize organic compounds and microorganisms. In this year, we discussed such instrumental analytical techniques as mass spectrometry and soft X-ray spectroscopy. One of the promising techniques to detect extant life is fluorometric

Astrobiology" is defined as origins, evolution, distribution and destiny of life in the Eart... more Astrobiology" is defined as origins, evolution, distribution and destiny of life in the Earth and elsewhere in space, which was first proposed by NASA in late 1990s. We organized the working group "Astrobiology Experiments in Earth Orbit" and have been discussed possible subjects of astrobiological experiments in Earth orbit. In 2006, we picked up one of the subjects, and it was proposed to JAXA as the "Tanpopo mission". In this year, we discussed the remaining problems around the Tanpopo mission, together with other possible subjects. In order to analyze organic compounds and microbes, we should have novel most sensitive techniques in the world. One of the promising techniques to detect extant life is fluorometric microscopy. In order to detect quite trace level of organics in dusts, mass microscopy techniques such as TOF-SIMS. These techniques can be used not only in the Tanpopo mission but also future missions to detect life on Mars and beyond. One of the...

MRS Proceedings, 1991

ABSTRACTThe chemical forms of iron minerals and uranyl species have been examined non-destructive... more ABSTRACTThe chemical forms of iron minerals and uranyl species have been examined non-destructively by visible microspectroscopy and electron microprobe analysis in order to obtain a better understanding of uranium redistribution and fixation mechanisms. The uranyl species are associated with sub-micron sized iron minerals, such as hematite (Fe2O3), goethite (FeOOH), and ferrihydrite (Fe4-5(OH,O)12). Additionally, some uranium is fixed to goethite in weathered chlorite grains. Sub-micron sized saleeite, Mg(UO2)2(PO4)2. 1OH2O, is the most probable uranyl phase associated with the iron minerals. This suggests that the uranium fixation in the vicinity of the Koongarra uranium ore deposits is the result of the coprecipitation and sorption of microcrystals of saleeite on to the iron minerals released during weathering of chlorite.

Kinetic heating experiments of organic material in the Tagish Lake chondrite were conducted in-si... more Kinetic heating experiments of organic material in the Tagish Lake chondrite were conducted in-situ under a micro FTIR. Two types of aliphatic C-H groups were revealed, one thermally fragile and the other being significantly more refractory.

Researches in organic geochemistry, 1992

Plants, 2020

Leaf water storage is a complex interaction between live tissue properties (anatomy and physiolog... more Leaf water storage is a complex interaction between live tissue properties (anatomy and physiology) and physicochemical properties of biomolecules and water. How leaves adsorb water molecules based on interactions between biomolecules and water, including hydrogen bonding, challenges our understanding of hydraulic acclimation in tall trees where leaves are exposed to more water stress. Here, we used infrared (IR) microspectroscopy with changing relative humidity (RH) on leaves of tall Cryptomeria japonica trees. OH band areas correlating with water content were larger for treetop (52 m) than for lower-crown (19 m) leaves, regardless of relative humidity (RH). This high water adsorption in treetop leaves was not explained by polysaccharides such as Ca-bridged pectin, but could be attributed to the greater cross-sectional area of the transfusion tissue. In both treetop and lower-crown leaves, the band areas of long (free water: around 3550 cm−1) and short (bound water: around 3200 cm−...

THE REVIEW OF HIGH PRESSURE SCIENCE AND TECHNOLOGY, 1998

In-situ IR measurements wereconducted with varying heating duration to study a time-dependent cha... more In-situ IR measurements wereconducted with varying heating duration to study a time-dependent changes (i) an increaseof the 3379cm-1 absorption peak at room temperature (RT) assigned to OH associated with Al3+ substitution for Si (OH(Al)) and (ii) a decrease of the 3482cm-1 peak (RT) assigned to OH (Al) including a influence of Li+ interstitial defects or Li-O-Al as acharge compensating role. These (i) and(ii) are consideredto be dueto an exchangeof Li+ with H+, since theseions become more diffusive at higher temperatures.

Tree Physiology, 2017

Recent studies in the tallest tree species suggest that physiological and anatomical traits of tr... more Recent studies in the tallest tree species suggest that physiological and anatomical traits of treetop leaves are adapted to waterlimited conditions. In order to examine water retention mechanism of leaves in a tall tree, infrared (IR) micro-spectroscopy was conducted on mature leaf cross-sections of tall Cryptomeria japonica D. Don from four different heights (51, 43, 31 and 19 m). We measured IR transmission spectra and mainly analyzed OH (3700-3000 cm −1) and CO (1190-845 cm −1) absorption bands, indicating water molecules and sugar groups, respectively. The changes in IR spectra of leaf sections from different heights were compared with bulk-leaf hydraulics. Both average OH band area of the leaf sections and leaf water content were larger in the upper-crown, while osmotic potential at saturation did not vary with height, suggesting higher dissolved sugar contents of upper-crown leaves. As cell-wall is the main cellular structure of leaves, we inferred that larger average CO band area of uppercrown leaves reflected higher content of structural polysaccharides such as cellulose, hemicellulose and pectin. Infrared microspectroscopic imaging showed that the OH and CO band areas are large in the vascular bundle, transfusion tissue and epidermis. Infrared spectra of individual tissue showed that much more water is retained in vascular bundle and transfusion tissue than mesophyll. These results demonstrate that IR micro-spectroscopy is a powerful tool for visualizing detailed, quantitative information on the spatial distribution of chemical substances within plant tissues, which cannot be done using conventional methods like histochemical staining. The OH band could be well reproduced by four Gaussian OH components around 3530 (free water: long H bond), 3410 (pectin-like OH species), 3310 (cellulose-like OH species) and 3210 (bound water: short H bond) cm −1 , and all of these OH components were higher in the upper crown while their relative proportions did not vary with height. Based on the spectral analyses, we inferred that polysaccharides play a key role in biomolecular retention of water in leaves of tall C. japonica.

Journal of Taphonomy, 2006

In order to evaluate alteration of calcareous nannoplankton assemblages during their deposition-d... more In order to evaluate alteration of calcareous nannoplankton assemblages during their deposition-diagenesis, a dissolution experiment of calcareous nannoplankton from a marine sediment sample was carried out. An assemblage of calcareous nannoplankton (coccoliths) found in surface sediments taken from the Caribbean Sea was put in stirred pure water with a fixed ionic strength (0.7 mol/l KCl) at 27.5°C to trace their dissolution behaviors. Temporal changes in pH and Ca concentration during the dissolution experiment indicated that the dissolution kinetics were similar to those found in the simple calcite system. By counting numbers of different species and taxonomic groups, the apparent dissolution rates were determined for each species and taxonomic group. The obtained individual dissolution rates differ among different species and taxonomic groups up to a factor of about 9. The resulted nannoplankton assemblages after dissolution were therefore very different from the original ones. This implies that the fossil assemblage can be altered during the deposition-diagenesis by carbonate dissolution processes.

Viva Origino, Mar 1, 1998

Agu Fall Meeting Abstracts, Dec 1, 2002