Determination of phase transition pressures of ZnTe under quasihydrostatic conditions   总被引：1，自引：0，他引：1  

Keiji Kusaba  Laurence Galoisy  Yanbin Wang  Michael T. Vaughan  Donald J. Weidner 《Pure and Applied Geophysics》1993,141(2-4):643-652

Pressure behavior of ZnTe at room temperature was studied using an X-ray energy dispersive method on a DIA type cubic anvil apparatus (SAM-85) at NSLS-X17B1. By using powdered polyethylene, the sample and NaCl for a pressure scale were held under quasihydrostatic conditions, which were confirmed by X-ray diffraction method. Two high-pressure phase transitions were confirmed using X-ray powder diffraction simultaneously with electrical resistance measurements. The phase transition pressures under quasihydrostatic conditions were determined to be 9.6 GPa, at which the resistance increased, and 12.0 GPa, which was the midpoint of a large resistance decrease. Errors in the pressure determinations were estimated to be less than 0.2 GPa. These pressure values may depend on grain size and anisotropic stress effects on the calibrant. From X-ray observation of ZnTe, the bulk modulus of the zinc blende structure was calculated to beK ₀=51(3) GPa andK ₀ =3.6(0.8), and the first transition at 9.6 GPa was found to have about 9% volume change. It was consistent with an anomaly in the pressure generating curves.  相似文献   

Note on the isolated vortices over the topographic-β     

Jun-Ichi Yano  Ichiro Yasuda 《Journal of Oceanography》1992,48(2):231-237

The behavior of the isolated vortices over the topographic-is considered with the quasi-geostrophic two-layer model, in the limit of very shallow upper layer, in the absence of planetary-. The results are compared with the observed Kurshio warm-core rings. When a ring drifts southward (northward) relative to the meridional mean current, it radiates (does not radiate) Rossby waves in the lower layer. Even when the lower layer is radiating, the decaying is very slow as long as the ring drifts closely to a background current.Current affiliation (from Feb. 1, 1992): NCAR, P.O. Box 3000, Boulder, Colorado 80307-3000, U.S.A.  相似文献   

Mineral parageneses and metamorphic P-T paths of ultrahigh-pressure eclogites from Kyrghyzstan Tien-Shan   总被引：3，自引：0，他引：3  

M. Tagiri  T. Yano  A. Bakirov  T. Nakajima  S. Uchiumi 《Island Arc》1995,4(4):280-292

Abstract Eclogites occur in three districts of the northern and southern parts of Tien-Shan. Three eclogites collected from the Aktyuz, Makbal and Atbashy districts were analyzed; the P-T paths of three eclogites were estimated by analyzing compositional growth zoning and retrograde reaction of garnet and omphacite. Aktyuz and Makbal eclogites have not preserved the prograde path. An Aktyuz eclogite that underwent a quartz eclogite facies metamorphism (about T = 600°C, P = 12 kbar) has recorded three stages of retrograde metamorphism. Four stages of retrograde metamorphism were recognized in a Makbal eclogite; the garnet-omphacite geothermometer gave about T = 560°C at 20 kbar as the highest metamorphic condition. Garnet from a garnetchloritoid-talc schist of the Makbal district includes quartz pseudomorphs after coesite; some units evidently underwent a low-temperature part of coesite eclogite fades metamorphism. Prograde and retrograde paths were recognized in an Atbashy eclogite; five stages of metamorphic reaction were observed in the Atbashy sample. The prograde path from stage I to stage III has been recorded in garnet and omphacite in which quartz pseudomorphs after coesite are included. The peak metamorphism of stage III took place at about 660°C at 25 kbar. The stages IV and V are retrograde. UHP eclogite facies metamorphism took place twice in Kyrghyzstan. The Aktyuz and Atbashy eclogites gave Rb-Sr mineral-isochron ages of about 750 Ma and 270 Ma, respectively. The K-Ar age of paragonite from the Makbal eclogite is about 480 Ma.  相似文献   

Upper and middle crustal deformation of an arc–arc collision across Hokkaido, Japan, inferred from seismic refraction/wide-angle reflection experiments     

Takaya Iwasaki  Keiji Adachi  Takeo Moriya  Hiroki Miyamachi  Takeshi Matsushima  Kaoru Miyashita  Testsuya Takeda  Takaaki Taira  Tomoaki Yamada  Kazuo Ohtake 《Tectonophysics》2004,388(1-4):59

The Hidaka Collision Zone (HCZ), central Hokkaido, Japan, is a good target for studies of crustal evolution and deformation processes associated with an arc–arc collision. The collision of the Kuril Arc (KA) with the Northeast Japan Arc (NJA), which started in the middle Miocene, is considered to be a controlling factor for the formation of the Hidaka Mountains, the westward obduction of middle/lower crustal rocks of the KA (the Hidaka Metamorphic Belt (HMB)) and the development of the foreland fold-and-thrust belt on the NJA side. The “Hokkaido Transect” project undertaken from 1998 to 2000 was a multidisciplinary effort intended to reveal structural heterogeneity across this collision zone by integrated geophysical/geological research including seismic refraction/reflection surveys and earthquake observations. An E–W trending 227 km-long refraction/wide-angle reflection profile found a complicated structural variation from the KA to the NJA across the HCZ. In the east of the HCZ, the hinterland region is covered with 4–4.5 km thick highly undulated Neogene sedimentary layers, beneath which two eastward dipping reflectors were imaged in a depth range of 10–25 km, probably representing the layer boundaries of the obducting middle/lower crust of the KA. The HMB crops out on the westward extension of these reflectors with relatively high Vp (>6.0 km/s) and Vp/Vs (>1.80) consistent with middle/lower crustal rocks. Beneath these reflectors, more flat and westward dipping reflector sequences are situated at the 25–27 km depth, forming a wedge-like geometry. This distribution pattern indicates that the KA crust has been delaminated into more than two segments under our profile. In the western part of the transect, the structure of the fold-and-thrust belt is characterized by a very thick (5–8 km) sedimentary package with a velocity of 2.5–4.8 km/s. This package exhibits one or two velocity reversals in Paleogene sedimentary layers, probably formed by imbrication associated with the collision process. From the horizontal distribution of these velocity reversals and other geophysical/geological data, the rate of crustal shortening in this area is estimated to be greater than 3–4 mm/year, which corresponds to 40–50% of the total convergence rate between the NJA and the Eurasian Plate. This means that the fold-and-thrust belt west of the HCZ is absorbing a large amount of crustal deformation associated with plate interaction across Hokkaido Island.  相似文献   

International Pellet Watch: Global monitoring of persistent organic pollutants (POPs) in coastal waters. 1. Initial phase data on PCBs, DDTs, and HCHs   总被引：1，自引：0，他引：1  

Yuko Ogata  Kaoruko Mizukawa  Satoru Iwasa  Yukie Mato  Keiji Okuda  Michio Murakami  Ruchaya Booyatumanondo  Le Quang Dung  Carlos Miguez  Charles Moore  Steven Weerts  Erick Burres  Michael Van Velkenburg  Richard C. Lang  Brenda Danner  Richard C. Thompson 《Marine pollution bulletin》2009,58(10):1437-1446

Samples of polyethylene pellets were collected at 30 beaches from 17 countries and analyzed for organochlorine compounds. PCB concentrations in the pellets were highest on US coasts, followed by western Europe and Japan, and were lower in tropical Asia, southern Africa and Australia. This spatial pattern reflected regional differences in the usage of PCBs and was positively correlated with data from Mussel Watch, another monitoring approach. DDTs showed high concentrations on the US west coast and in Vietnam. In Vietnam, DDT was predominant over its metabolites (DDE and DDD), suggesting the principal source may be current usage of the pesticide for malaria control. High concentrations of pesticide HCHs were detected in the pellets from southern Africa, suggesting current usage of the pesticides in southern Africa. This study demonstrates the utility and feasibility of the International Pellet Watch approach to monitor POPs at a global scale.  相似文献   

Vector Magnetic Field Synoptic Charts from the <Emphasis Type="Italic">Helioseismic and Magnetic Imager</Emphasis> (HMI)     

Yang Liu  J. Todd Hoeksema  Xudong Sun  Keiji Hayashi 《Solar physics》2017,292(2):29

Vector magnetic field synoptic charts from the Helioseismic and Magnetic Imager (HMI) are now available for each Carrington Rotation (CR) starting from CR 2097 in May 2010. Synoptic charts are produced using 720-second cadence full-disk vector magnetograms remapped to Carrington coordinates. The vector field is derived from the Stokes parameters (\(I, Q, U, V\)) using a Milne–Eddington-based inversion model. The \(180^{\circ}\) azimuth ambiguity is resolved using the minimum energy algorithm for pixels in active regions and for strong-field pixels (the field is greater than about 150 G) in quiet-Sun regions. Three other methods are used for the rest of the pixels: the potential-field method, the radial acute-angle method, and the random method. The vector field synoptic charts computed using these three disambiguation methods are evaluated. The noise in the three components of the vector magnetic field is generally much higher in the potential-field method charts. The component noise levels are significantly different in the radial-acute charts. However, the noise levels in the random-method charts are lower and comparable. The assumptions used in the potential-field and radial-acute methods to disambiguate the weak transverse field introduce bias that propagates differently into the three vector-field components, leading to unreasonable pattern and artifacts, whereas the random method appears not to introduce any systematic bias. The current sheet on the source surface, computed using the potential-field source-surface model applied to random-method charts, agrees with the best solution (the result computed from the synoptic charts with the minimum energy algorithm applied to each and every pixel in the vector magnetograms) much better than the other two. Differences in the synoptic charts determined with the best method and the random method are much smaller than those from the best method and the other two. This comparison indicates that the random method is better for vector field synoptic maps computed from near-central meridian data. The vector field synoptic charts provided by the Joint Science Operations Center (JSOC) are therefore produced with the random method.  相似文献   

Relation Between Coronal Hole Areas and Solar Wind Speeds Derived from Interplanetary Scintillation Measurements     

Munetoshi Tokumaru  Daiki Satonaka  Ken’ichi Fujiki  Keiji Hayashi  Kazuyuki Hakamada 《Solar physics》2017,292(3):41

We investigate the relation between coronal hole (CH) areas and solar wind speeds during 1995?–?2011 using the potential field (PF) model analysis of magnetograph observations and interplanetary scintillation (IPS) observations by the Institute for Space-Earth Environmental Research (formerly Solar-Terrestrial Environment Laboratory) of Nagoya University. We obtained a significant positive correlation between the CH areas (\(A\)) derived from the PF model calculations and solar wind speeds (\(V\)) derived from the IPS observations. The correlation coefficients between them are usually high, but they drop significantly in solar maxima. The slopes of the \(A\)?–?\(V\) relation are roughly constant except for the period around solar maximum, when flatter or steeper slopes are observed. The excursion of the correlation coefficients and slopes at solar maxima is ascribed partly to the effect of rapid structural changes in the coronal magnetic field and solar wind, and partly to the predominance of small CHs. It is also demonstrated that \(V\) is inversely related to the flux expansion factor (\(f\)) and that \(f\) is closely related to \(A^{-1/2}\); hence, \(V \propto A^{1/2}\). A better correlation coefficient is obtained from the \(A^{1/2}\)?–?\(V\) relation, and this fact is useful for improving space weather predictions. We compare the CH areas derived from the PF model calculations with He i 1083 nm observations and show that the PF model calculations provide reliable estimates of the CH area, particularly for large \(A\).  相似文献   

Mineralogy and geochemistry of shallow sediments of Sonargaon, Bangladesh and implications for arsenic dynamics: Focusing on the role of organic matter     

Ashraf Ali Seddique  Harue MasudaMuneki Mitamura  Keiji ShinodaToshiro Yamanaka  Shinji NakayaKazi Matin Ahmed 《Applied Geochemistry》2011,26(4):587-599

Mineralogy and geochemistry of modern shallow sediments (up to 5 m thick) within the zone of water table fluctuations were studied to determine the likely sources and processes responsible for releasing As into groundwater. Samples were collected from different geological settings with varying groundwater As concentrations during dry (December 2005) and wet (September 2006) seasons at Sonargaon, Bangladesh. Stratigraphic sequences of the studied sediments showed three distinct lithofacies, viz. clayey-silt, silty-clay, and silty-very fine sand, corresponding to fine-grained overbank associations. Total As concentrations of shallow sediments ranged from <1 to 16 mg/kg without a significant difference in the range of As concentrations between the seasons. Sequential chemical extraction analysis of As revealed that >80% of the As was fixed in insoluble and organic phases, while the amount of As in reducible and acid-soluble phases was very low (<20%) and varied inversely with total As content. Total As concentration varied with mica content (muscovite and biotite) and its related elements (Al, Mg and Fe), but not with total organic C, suggesting that biotite is the major host phase of As. Arsenic appears to be liberated from biotite and/or other As-bearing minerals via chemical weathering (i.e., hydration-decomposition), either from the near-surface sediments which are subject to seasonal cycling of the redox conditions, or from within the aquifer sediments. Once released, progressive diagenesis to form As-bearing organic matter may be responsible for controlling As distribution in the sediments and coexisting groundwater of the study area.  相似文献   

Petrology and mineralogy of the shock-melted H chondrites Yamato–791088 and LaPaz Ice Field 02240     

Takafumi Niihara  Naoya Imae  Keiji Misawa  Hideyasu Kojima   《Polar Science》2011,4(4):558-573

We studied the petrology and mineralogy of two types of shock-melted H chondrites: Yamato (Y)–791088 and LaPaz Ice Field (LAP) 02240. Y–791088, which consists of numerous coarse-grained relict phases (40%) and euhedral fine-grained minerals solidified from the shock melt (60%), experienced incomplete melting; a quiescent melt is indicated by the existence of abundant relict phases, pseudomorphed chondrules, and two types of glass. LAP 02240, which consists of small amounts of coarse-grained relict phases (～10%) and fine-grained minerals (～90%), experienced near-complete melting; a rapidly cooled mobilized melt is indicated by the homogeneous compositions of glass and opaque veins.The homogeneous compositions of relict olivines indicate that the precursors of both chondrites were equilibrated H chondrites. The melting features of Y–791088 and LAP 02240 are very similar to those of Y–790964 (LL) and the fine-grained lithology of Y–790519 (LL), respectively. These two types of shock-melted ordinary chondrites possibly formed in situ during dike formation. The quiescent melt is thought to have originated from the injection of shock-heated chondrite blocks into mobilized melt. These two types of melting could have occurred during dike formation on the H chondrite parent body. The textures of the two types of shock melts were not simply affected by the degree of shock melting: they were also controlled by the degree of shear stress.  相似文献   

Deep two-dimensional turbulence: An idealized model for atmospheric jets of the giant outer planets     

Jun-Ichi Yano  Olivier Talagrand  Pierre Drossart 《地球物理与天体物理流体动力学》2013,107(2):137-150

The present paper proposes a new type of two–dimensional turbulence with a deep configuration as an idealization of the dynamics of the global circulations of the Jovian atmospheres under the constraint of the Taylor–Proudman theorem. A major difference of the deep two-dimensional turbulence from a standard shallow version is that the former reverses the sign of the planetary β-effect, leading to an opposite sign for the equatorial jet under the homogenization tendency of the potential vorticity. As a result, a westerly (prograde) equatorial jet is generated, which contrasts with the easterly (retrograde) equatorial jet obtained using the shallow configuration. The results suggest that the zonal flows of Jupiter and Saturn are probably of deep origin, whereas those of Uranus and Neptune are likely to be of shallow origin.  相似文献