Distribution of Planetesimals around a Protoplanet in the Nebula Gas     

Hidekazu Tanaka  Shigeru Ida 《Icarus》1996,120(2):371-386

We have developed a semi-analytic method of calculating the changes in heliocentric Keplerian orbital elements due to gravitational scattering by a protoplanet as a three-body problem. In encounters with high incident velocities, either the gravity of the protoplanet or the solar gravity can be regarded as perturbation force. In close encounters, by taking into account the solar gravity as a perturbation, we modified the two-body gravitational scattering. On the other hand, in slightly distant encounters, we apply the perturbing force of the protoplanet to the heliocentric Keplerian orbit of planetesimals. As a result, as for high-velocity encounters, the three-body problem is semi-analytically solvable. Our semi-analytic method can reproduce the numerical result of the orbital changes of individual planetesimals for the broad range of high-energy encounters with surprising high accuracy. We found that our method is valid under the conditions (i)b₀? 2 and (ii) (e²₀+i²₀− b²₀)^1/2? 4, wheree₀andi₀are eccentricity and inclination of relative motion normalized by the reduced Hill radius andb₀is the difference between semimajor axes normalized by the Hill radius. Though our method needs some numerical procedure, its cpu time is negligibly short compared with that of the direct orbital integration. In simulation of orbital evolution of planetesimals around a protoplanet in the gas, which we will perform in the subsequent paper, most encounters can be calculated by the semi-analytic method. This makes it possible to perform the long term (∼10⁵years) orbital calculation of ∼10^3–4planetesimals.  相似文献   

A crystal chemical study of protoanthophyllite: orthoamphiboles with the protoamphibole structure     

Shigeho Sueno  Shigeru Matsuura  G. V. Gibbs  M. B. Boisen Jr. 《Physics and Chemistry of Minerals》1998,25(5):366-377

Two new protoamphibole-type amphiboles with space group type Pnmn, have been found in nature: protoferro-anthophyllite (Fe_0.80Mn_0.20)₂ (Fe_0.98Mg_0.02)₅ (Si₄O₁₁)₂(OH)₂, and protomangano-ferro-anthophyllite, (Mn_0.70Fe_0.30)₂ (Fe_0.82Mg_0.18)₅ (Si₄O₁₁)₂(OH)₂. Protoferro-anthophyllite (PFA) occurs in pegmatites at both Gifu Prefecture, Japan and at Cheyenne Mountain, El Paso County, Colorado, USA. Protomangano-ferro-anthophyllite, (PMFA) occurs in pegmatites at Fukushima Prefecture and in a Mn mine at Tochigi Prefecture, Japan. Structure determinations of the two amphiboles show that both are isostructural with the synthetic fluorian-amphibole, protoamphibole (= protofluorian-lithian-anthophyllite). A calculation of the procrystal electron density distributions, the bond paths and the bond critical point properties of PFA, PMFA, grunerite and protoamphibole indicates that the M4 cation in these amphiboles is 4-coordinated. A calculation of the electron density distributions at the Becke3LYP/6-311G(2d,p) level for model silicate tetrahedra for these amphiboles and anthophyllite reveals that the value of the electron density at the bond critical points, ρ(r _c ), for the SiO(nbr) bonds is larger, on average (0.93 e/ų), than that for the SiO(br) bonds (0.90 e/ų). The observed SiO bond lengths decrease linearly with increasing ρ(r _c ) while the magnitudes of the curvatures of ρ(r _c ) both perpendicular and parallel to the bonds and the Laplacian of ρ(r _c ) each increases. These trends are associated with an increase in the electronegativity of the Si cation, a possible increase in the covalent character of the SiO bond and a tendency for SiO(nbr) bonds to be involved in wider OSiO angles than SiO(br) bonds. It is possible, if not likely, that protoanthophyllite has often been misidentified as anthophyllite.  相似文献   

Mineralogical Associations of Arsenic and Antimony in Thirty Five Geochemical Reference Materials by Sequential Extraction with Hydride Generation and Atomic Absorption Spectrometry   总被引：2，自引：0，他引：2  

Shigeru Terashima  Masahiro Taniguchi 《Geostandards and Geoanalytical Research》1998,22(1):103-112

A method is described to estimate the chemical forms of arsenic (As) and antimony (Sb) in a variety of geochemical reference materials, combining a sequential extraction scheme with hydride generation and atomic absorption spectrometry (HG-AAS). The fractions dissolved by sequential extraction are empirically defined as the exchangeable, EDTA soluble, oxide, sulfide and residual fractions. The amount of As and Sb in the EDTA soluble fraction have been derived mainly from oxide phases, and partly from carbonate minerals. Most sulfide minerals in common geological samples were considered to be dissolved with the digestion of 0.7 mol l⁻¹ NaOCl, but only small fraction of arsenopyrite and loellingite in ores could be dissolved in this way. Satisfactory agreement was observed between the sum of the As or Sb values from exchangeable to residual fractions and the reported total As or Sb values, with a few exceptions. Analytical results of As and Sb for thirty five geochemical reference materials are tabulated, and geochemical and mineralogical features are discussed.  相似文献   

X-ray photoelectron spectroscopic study on the goethites with variations in crystallinity and morphology: their effects on surface hydroxyl concentration   总被引：1，自引：0，他引：1  

Takuya Echigo  Tamao Hatta  Seiko Nemoto  Shigeru Takizawa 《Physics and Chemistry of Minerals》2012,39(9):769-778

We examined the effects of crystallinity and crystal morphology on surface hydroxyl concentration of goethite using four kinds of goethite samples prepared by aging a hydrous ferric oxide (ferrihydrite) at different temperatures ranging from 4 to 70?°C. These samples were analyzed with the following methods: powder X-ray diffraction, Brunauer–Emmett–Teller surface area analyzer, atomic force microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and high-resolution X-ray photoelectron spectroscopy (XPS). The first three analyses showed that the goethite aged at lower temperature has lower crystallinity, smaller particle size and lower aspect ratio. The ATR-FTIR analysis revealed that the OH-stretching band of goethite aged at 4?°C moves to slightly higher wavenumber than those of the samples aged at higher temperatures. Their XPS analyses demonstrated that variation in the concentration of surface hydroxyl group ranges from 6.6 (nm^?2) for the sample aged at 4?°C to 7.7 (nm^?2) for the sample aged at 70?°C. Considering the analytical depth of the XPS (~5?nm), photoelectrons are emitted from the uppermost layers of the analyte. Hence, XPS results are interpreted to reflect variations in the morphology of fine crystals (<100?nm thick). The morphology of the present goethites can be characterized by their aspect ratio, in other words, the degree of development of (110)–(110) intersection edges at which protons preferentially accumulate. This variation in the concentration of surface hydroxyl group revealed by XPS analysis offers experimental evidence for the effects of crystallinity and morphology on the surface chemical properties of goethite.  相似文献   

A measurement of H₀ from Ryle Telescope, ASCA and ROSAT observations of Abell 773     

Richard Saunders  Rüdiger Kneissl  Keith Grainge  William F. Grainger  Michael E. Jones  Alessia Maggi  Rhiju Das  †  Alastair C. Edge  Anthony N. Lasenby  G. G. Pooley  Shigeru J. Miyoshi  Taisuke Tsuruta  Koujun Yamashita  Yuzuru Tawara  Akihiro Furuzawa  Akihiro Harada  Izamu Hatsukade 《Monthly notices of the Royal Astronomical Society》2003,341(3):937-940

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Development of the core‐suspended isolation system     

Yutaka Nakamura  Masaaki Saruta  Akira Wada  Toru Takeuchi  Shigeru Hikone  Teiichi Takahashi 《地震工程与结构动力学》2011,40(4):429-447

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Decrease in anthropogenic nutrients and its effect on the C/N/P molar ratio of suspended particulate matter in hypertrophic Dokai Bay (Japan) in summer     

Kenichiro Hamada  Naoko Ueda  Machiko Yamada  Kuninao Tada  Shigeru Montani 《Journal of Oceanography》2012,68(1):173-182

Biologically important nutrient concentrations in Dokai Bay have declined as a result of reductions in anthropogenic inputs of total nitrogen and total phosphorus. A decrease in nutrient concentrations affects phytoplankton growth, thereby changing the biochemical characteristics of autochthonous particulate matter. We therefore investigated changes in the C/N/P molar ratio of suspended particulate matter (SPM) in the summer, when phytoplankton growth is vigorous, before environmental quality standards (EQSs) were attained (1995–1998) and afterward (2006–2009). We found that the ratio of particulate organic nitrogen (PON) to particulate phosphorus (PP) changed in conjunction with changes in the ratio of dissolved inorganic nitrogen to dissolved inorganic phosphorus (DIP) that resulted from reductions in nutrient loading. Furthermore, we suggest that because the DIP concentration in seawater was high before EQSs were attained, inorganic phosphorus was possibly adsorbed onto SPM. After the attainment of EQSs, however, the DIP concentration fell, and PON/PP was high. Phosphorus limitation of phytoplankton growth in the mouth of the bay may explain the high PON/PP ratios after EQS attainment.  相似文献   

The influence of environmental variability on silicate exchange rates between sediment and water in a shallow-water coastal ecosystem,the Seto Inland Sea,Japan   总被引：2，自引：0，他引：2  

Srithongouthai S  Sonoyama Y  Tada K  Montani S 《Marine pollution bulletin》2003,47(1-6):10-17

Silicate regeneration was determined in a shallow-water coastal ecosystem (Shido Bay, the Seto Inland Sea, Japan) during 1999-2000. The present study was carried out directly by core incubation and by determining gradients of dissolved silicate (DSi) in the pore water. Incubated fluxes ranged from 25.5 to 132.6 mgSim(-2)d(-1), and were 1.6-21.6 times greater than diffusive fluxes (5.4-43.3 mgSim(-2)d(-1)). The disparity between fluxes measured by core incubation and modeling pore water indicated that other physical, chemical or biological processes, in addition to diffusion of DSi from below, contribute to DSi fluxes measured during the incubation of undisturbed cores. A regression analysis revealed that water temperature and salinity explained 24% and 23%, respectively, of season to season variability in incubated fluxes. Microphytobenthos was responsible for 37% of the variability in measured rate of DSi fluxes, with greatly reducing DSi release rates due to their own DSi demand. Moreover, the inverse relationship between the DSi fluxes and biogenic silica (Bio-Si) concentrations in the surface sediment, suggested that about 41% of the variability in the DSi fluxes were explained by Bio-Si concentrations in the surface sediment. As a result, Shido Bay showed silicate regeneration of incubated cores to be a consequence of Bio-Si dissolution depending on microphytobenthos, temperature and salinity, while diffusive fluxes appeared to be limited by DSi in the pore water. An annual average of DSi flux (68.7+/-32.9 mgSim(-2)d(-1)) from the sediments to the water column corresponds to 38% of DSi, required for primary production by phytoplankton in Shido Bay.  相似文献   

DATABASE ON INTERNET FOR GEOLOGICAL SURVEY OF JAPAN GEOCHEMICAL REFERENCE SAMPLES     

Noboru IMAI  Hiroshi SAKURAMACHI  Shigeru TERASHIMA  Shiro ITOH  Atsushi ANDO 《Geostandards and Geoanalytical Research》1996,20(2):161-164

A database on thirty-one Geological Survey of Japan (GSJ) geochemical reference samples has been set up on Internet which allows the retrieval of recommended or preferable values, compiled data, location, sample preparation and other relevant information. The URL location on WWW server is: http://www.aist.go.jp./RIODB/geostand/welcome.html  相似文献   

Determination of Indium and Tellurium in Fifty Nine Geological Reference Materials by Solvent Extraction and Graphite Furnace Atomic Absorption Spectrometry     

Shigeru Terashima 《Geostandards and Geoanalytical Research》2001,25(1):127-132

The indium (In) and tellurium (Te) contents of fifty nine geological reference materials, issued by several reference material producers (USGS, CRPG, ANRT, GIT-IWG and GSJ) have been determined by graphite furnace atomic absorption spectrometry, after aqua regia and HF digestion, and extraction of iodide complexes with trioctylmethylammonium (TOMA) - metyl isobutyl ketone (MIBK). Although the interferences from most elements can be minimised by the addition of palladium solution as the matrix modifier, large concentrations of Bi, Cu, Pb or Sn suppress the absorbance of In and/or Te. Samples for analysis were therefore restricted to those in which the concentrations of these interfering elements did not cause a significant interference. The limit of detection was 0.2 ng g⁻¹ In and Te for 1 g test portions. The agreement between the reported results and published data is satisfactory.  相似文献