Seismic Signals Induced by Snow Avalanche Flow     

Kishimura  K.  Izumi  K. 《Natural Hazards》1997,15(1):89-100

In this paper some observations and their analysis are presented dealing with the link between seismic signals and avalanche flow. The measurements during the passage of avalanches showed a specific spindle pattern which was quite different from the one of natural earthquakes. The general trend strongly depended on the topographic features of the avalanche path, and as a result we could estimate avalanche velocity. The running power spectrum showed a meaningful shift of the dominant peak from the front to the rear part of the flow.  相似文献   

Characterization of the amorphous state in metamict silicates and niobates by EXAFS and XANES analyses     

Izumi Nakai  Junji Akimoto  Masayuki Imafuku  Ritsuro Miyawaki  Yoshinori Sugitani  Kichiro Koto 《Physics and Chemistry of Minerals》1987,15(2):113-124

X-ray absorption spectroscopy using synchrotron radiation has been applied to the investigation of the coordination geometries around Y, Zr and Nb atoms in metamict zircon, gadolinite, fergusonite, euxenite and samarskite. EXAFS and XANES spectra of their crystalline counterparts and synthetic compounds including ZrO₂, Y₂O₃, YNbTiO₆, YNbO₄, LiNbO₃, and NiNb₂O₆ were also measured for comparison. Metamict zircon shows a significant decrease in its Zr-O bond distances accompanying an increase in distortion of the Zr-O coordination polyhedra as compared with crystalline zircon. On the contrary, the average Nb-O bond distances and the symmetry of the coordination polyhedra around the Nb atoms in metamict euxenite and samarskite resemble those in the crystalline euxenite. Compared with crystalline fergusonite, a decrease in the distortion of the Nb-O octahedra is observed in metamict fergusonite. The structures of the second nearest neighbors (the metal-metal interactions) are largely disrupted in the metamict specimens except for metamict zircon and samarskite with high trivalent iron concentration. Nb in metamict samarskite is in octahedral coordination by oxygen and is similar to that in euxenite.  相似文献   

Ambient air measurements of six bifunctional carbonyls in a suburban area     

Ricardo Ortiz  Hiroyuki Hagino  Kazuhiko Sekiguchi  Qingyue Wang  Kazuhiko Sakamoto   《Atmospheric Research》2006,82(3-4):709

Low-molecular-weight carbonyl compounds, generated by photochemical reactions in the atmosphere and found in the exhaust of motor vehicles, have recently come to the attention of researchers because some of them are suspected carcinogens or mutagens. Six bifunctional carbonyl compounds were detected and measured in a suburban site 30 km northwest of the Tokyo metropolitan area. Samples were taken on five sunny days between 2 August and 11 August 2003 with a low-volume denuder and three-filter tandem system using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) as a sorbent. Bifunctional carbonyls were measured by gas chromatography–mass spectrometry after two derivatization processes with PFBHA and N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA). The average total (gas plus particle) concentrations were 162.8 ng m^− 3 for pyruvic acid, 113.7 ng m^− 3 for methylglyoxal, 36.0 ng m^− 3 for glycolaldehyde and 58.6 ng m^− 3 for glyoxal.  相似文献   

Influence of ignimbrite on the chemistry of river water in Shirasu plateau,Japan     

Katsuro Anazawa  Hayao Sakamoto  Takashi Tomiyasu 《Hydrogeology Journal》2007,15(2):409-417

River, rain and spring water samples from a region covered in “Shirasu” ignimbrite were collected on Kyushu Island, Japan. The analytical results were subjected to multivariate statistical analysis and stoichiometric calculation to understand the geographical distribution of chemical components in water and to extract geochemical underlying factors. The multivariate statistical analysis showed that the river-water chemistry is only slightly influenced by hot springs or polluted waters, but is highly controlled by weathering of ignimbrite. On the basis of the stoichiometric calculation based on water–rock interaction, the water chemistry was successfully estimated by a simple equation:\({\left[ {{\text{Si}}} \right]}{\text{ = 2}}{\left[ {{\text{Na}}^{{\text{ + }}} } \right]}{\text{ + }}{\left[ {{\text{Mg}}^{{{\text{2 + }}}} } \right]}\) in the upstream area, complemented by \({\left[ {{\text{Si}}} \right]}{\text{ = }}{\left[ {{\text{Na}}^{{\text{ + }}} } \right]}{\text{ - 3}}{\left[ {{\text{K}}^{{\text{ + }}} } \right]}{\text{ + }}{\left[ {{\text{Mg}}^{{{\text{2 + }}}} } \right]}{\text{ - 2}}{\left[ {{\text{Ca}}^{{{\text{2 + }}}} } \right]}\) in the downstream area.  相似文献   

Characterization of Banded Iron Formations by Two-Dimensional XRF Imaging and XANES Analyses     

Masaya MATSUNAGA  Katsunori FUKUDA  Yasuhiro KATO  Izumi NAKAI 《Resource Geology》2000,50(1):75-81

Abstract: Synchrotron radiation-induced X–ray fluorescence (SR–XRF) and conventional X-ray fluorescence (XRF) analyses were applied to determine the distributions of iron, manganese, calcium, titanium, and silicon, and chemical forms of iron and trace manganese in three banded iron formation (BIF) samples. The XRF imagings on the weathered and altered BIF from the Cleaverville Formation (3. 3–3. 1 Gyr), Western Australia, showed redistributions of iron, calcium, and manganese with the disappearance of the primary bandings, while, in contrast, titanium preserved its primary depositional distribution. The XRF imagings on the BIF from the Hamersley Group (2. 5 Gyr), Western Australia, showed that manganese and titanium distribute originally at boundary region between the iron-rich mesoband and the silica-rich mesoband. The X-ray Absorption Near Edge Structure (XANES) analysis revealed that the chemical forms of manganese and iron well represent the rhythmic change of the bandings.  相似文献   

Balloon-Borne Hard X-Ray Spectrometer Using CdTe Detectors     

K. Kobayashi  S. Tsuneta  T. Tamura  K. Kumagai  Y. Katsukawa  M. Kubo  Y. Sakamoto  N. Kohara  T. Yamagami  Y. Saito  K. Mori 《Solar physics》2008,250(2):431-441

Spectroscopic observation of solar flares in the hard X-ray energy range, particularly the 20 ∼ 100 keV region, is an invaluable tool for investigating the flare mechanism. This paper describes the design and performance of a balloon-borne hard X-ray spectrometer using CdTe detectors developed for solar flare observation. The instrument is a small balloon payload (gondola weight 70 kg) with sixteen 10×10×0.5 mm CdTe detectors, designed for a 1-day flight at 41 km altitude. It observes in an energy range of 20−120 keV and has an energy resolution of 3 keV at 60 keV. The second flight on 24 May 2002 succeeded in observing a class M1.1 flare.  相似文献   

Effects of large-scale wind on the Kuroshio path south of Japan in a 60-year historical OGCM simulation     

Hiroyuki Tsujino  Shiro Nishikawa  Kei Sakamoto  Norihisa Usui  Hideyuki Nakano  Goro Yamanaka 《Climate Dynamics》2013,41(9-10):2287-2318

The effects of large-scale wind forcing on the bimodality of the Kuroshio path south of Japan, the large meander (LM) and non-large meander (NLM), were studied by using a historical simulation (1948–2007) with a high-resolution Ocean general circulation models (OGCM). The Kuroshio in this simulation spent much time in the NLM state, and reproduced several aspects of its long-term path variability for the first time in historical OGCM simulation, presumably because the eddy kinetic energy was kept at a moderate level. By using the simulated fields, the relationships between wind forcing (or Kuroshio transport) and path variation proposed by past studies were tested, and specific roles of eddies in those variations were investigated. The long-term variation of the simulated net Kuroshio transport south of Japan was largely explained by the linear baroclinic Rossby wave adjustment to wind forcing. In the simulated LM events, a triggering meander originated from the interaction of a wind-induced positive sea surface height (SSH) anomaly with the upstream Kuroshio and was enlarged by cyclonic eddies from the recirculation gyre. The cyclonic eddy of the trigger meander was followed by a sizable anticyclonic eddy on the upstream side. Subsequently, a weak (strong) Kuroshio favored the LM (NLM). The LM tended to be maintained when the Kuroshio transport off southern Japan was small, and increasing Kuroshio transport promoted decay of an existing LM. The supply of disturbances from upstream, which is related to the wind-induced SSH variability at low latitudes, contributed to the maintenance of an existing LM.  相似文献   

The Effect of Wet Grinding on the Oxidation of Titanomagnetites   总被引：1，自引：0，他引：1  

N. Sakamoto  P. I. Ince  W. O'Reilly 《Geophysical Journal International》1968,15(5):509-515

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On measuring settlement by magnetic method at any depth     

Keiichiro Taniguchi  Harushige Kusumi  Tateshi Sakamoto  Koichi Kimura 《Marine Georesources & Geotechnology》2013,31(1):81-98

Abstract

When artificial islands are constructed, they are subject to surface subsidence, which is the resultant sum of the consolidation strata, many of which seem differ in character. When these strata are soft and thick, or heavily loaded, it becomes very difficult to estimate how much settlement will eventually take place, and over how long a period. For the estimate to be accurate, the settlement characteristics of each layer must first be determined.

For this purpose, the authors have investigated a new method of measuring settlement, based on two unique principles. One principle is the application of a permanent magnet as an indicator of settlement, and the other is the exploitation of semiconductor, magneto‐resistance elements for detecting the magnetic fields. In advance of the observation, the magnets are forced into the earth, being pushed out through the bore‐hole casing by the oil jack at suitable depths and intervals. The small‐sized magneto‐resistance element is essential to the practicality and efficiency of this method.

In this study, the principles of this method, measuring procedure, the special characteristics and potential of this system, and the results of field trials are described.  相似文献   

Mechanisms of uranium mineralization by the yeast Saccharomyces cerevisiae     

Toshihiko Ohnuki  Takuo Ozaki  Fuminori Sakamoto  Eiichi Wakai  Haruyuki Iefuji 《Geochimica et cosmochimica acta》2005,69(22):5307-5316

We determined the association of uranium in yeast cells S. cerevisiae grown in medium containing high (1 g · L^-1) or low (0.2 g · L^-1) concentrations of phosphate after exposure for 96 h to a 4 × 10^-4 mol · L^-1 U(VI) solution at pH 3.2 or 4.7. The analysis was made using a field emission scanning electron microscope equipped with energy dispersive spectroscopy (FESEM-EDS), transmission electron microscopy (TEM), and visible diffuse reflectance spectrometry. Cells grown in the high-phosphate medium rapidly accumulated U(VI) from solution at pH 3.2 over the first 24 h, followed by a slow uptake until 96 h, whereas in cells grown in low-phosphate medium, U(VI) accumulation reached a steady state within 24 h. FESEM-EDS analyses revealed the formation of a U(VI)-bearing precipitate on the yeast cells grown in high-phosphate medium after only 48 h exposure; no precipitate was detected on cells grown in low-phosphate medium up to 96 h. These results suggest that sorption onto the cell surfaces was the dominant process initially. Analysis of the U(VI)-bearing precipitates by all three methods demonstrated the presence of H-autunite, HUO₂PO₄ · 4H₂O. Thermodynamic calculations suggest that the chemical compositions of the solutions containing yeast grown in high-phosphate medium were undersaturated with respect to H-autunite, but were supersaturated with ten times more U(VI) and P than were actually observed. Apparently, the sorbed U(VI) on the cell surfaces reacts with P released from the yeast to form H-autunite by local saturation. The U(VI) uptake by yeast cells grown in high phosphate medium at pH 4.7, along with the thermodynamic calculation, indicated that more H-autunite is precipitated in neutral pH solution than in acid solution. Thus, U(VI)-phosphate mineralization on the cells of microorganisms should be taken into account for predicting U(VI) mobility in the environment.  相似文献