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21.
Naoya Miyoshi Hisao Satoh Yoshiaki Yamaguchi Harue Masuda 《Geostandards and Geoanalytical Research》2003,27(1):91-98
Five synthetic silica glasses have been prepared for microprobe determination of trace aluminium in quartz. The glasses were synthesized from tetraethoxysilane (TEOS) into which between 0 and 1431 μg g-1 aluminium had been doped. The aluminium concentrations of the glasses were independently determined by ICP-AES analysis. X-ray wavelength shift in the Al Kα peak was minimised relative to unknown quartz samples when these glasses were used for calibration. A set of these five glasses yielded a linear calibration line, and are available for trace aluminium analysis of quartz in routine microprobe systems. 相似文献
22.
Reaction of juvenile flounder to grid separators 总被引：1，自引：0，他引：1
Matsushita Yoshiki; Fujita Kaoru; Ikegami Naoya; Ohata Satoshi 《ICES Journal of Marine Science》2004,61(7):1174-1178
23.
Naoya Wada 《Polar research》1999,18(2):261-268
To determine the factors restricting plant reproduction in front of a glacier, the gender expression and seed production of Dryas octopetala L. (Rosaceae) were observed, as well as the grazing pattern of reindeer on flowers, near Brøggerbreen (Brøgger Glacier), which is near Ny-Ålesund (78° 55'N, 11° 56'E), Svalbard. Three hundred shoots with flowers and flower buds were randomly tagged in early July 1996. Between then and the end of flowering in late July, 100 (33%) flowers and buds were grazed by reindeer. Out of the surviving flowers, 145 (76%) shoots had hermaphrodite flowers, while 45 (24%) shoots had male flowers without a developed gynocium. Male flowers, which appeared later than hermaphrodite flowers in the population, were significantly smaller than hermaphrodite flowers in dry weight. In the hermaphrodite flowers, moreover, smaller flowers showed lower dry-weight allocation to the gynoecium as compared to larger flowers. During the observation, hermaphrodite flowers did not produce any developed seeds under a natural condition (0% seed-set). Cross-pollinated flowers showed 8% seed-set. On the other hand, flowers which were artificially warmed in small greenhouses during the flowering period showed 60% seed-set, regardless of cross-pollination or autodeposition of pollen from anthers to stigma (self-pollination). Thus, it was found that grazing, gender variation in relation to the length of the growing season and the flower size, and - in the floweriing period - low temperature rather than pollinator limitation strongly affected the seed production of D. octopetala in the population studied. 相似文献
24.
Michael E. Zolensky Atsushi Takenouchi Takashi Mikouchi Timothy Gregory Kunihiko Nishiizumi Marc W. Caffee Michael A. Velbel Daniel K. Ross Andrew Zolensky Loan Le Naoya Imae Akira Yamaguchi 《Meteoritics & planetary science》2021,56(1):49-55
Cosmic ray exposure (CRE) ages of CM chondrites have been found to have multiple peaks (as many as four), in stark contrast to other groups of chondrites (Nishiizumi and Caffee 2012; Herzog and Caffee 2014). In this study, we sought correlations between the CRE ages and petrography of CM chondrites, and we conclude that the degree of aqueous alteration does appear to vary with the CRE ages—the CMs displaying the most aqueous alteration all have relatively short exposure ages. However, some CMs with low degrees of alteration also have short exposure ages—thus, this apparent correlation is not exclusive. We also found a definite inverse relation between the number of distinctive lithologies in a CM and its exposure age, which could indicate different responses of homogeneous and heterogeneous meteoroids to the space environment between their onset of exposure (exhumation and ejection from the parent body) and arrival at Earth. Breccias have more internal surfaces of lithologic discontinuity, possibly resulting in weaker meteoroids that disintegrate more readily than their more homogeneous counterparts. Our results suggest that CM chondrite regoliths consist of numerous genomict lithologies in a breccia with millimeter‐ to decimeter‐scale clasts, with varying degree of heating/metamorphism. 相似文献
25.
Identification and characterization of small extraterrestrial samples, such as small Antarctic meteorites <~1 cm, require the development of convenient laboratory‐based nondestructive analytical techniques using X‐ray diffraction (XRD). We explore the characterization criteria using an X‐ray diffractometer with a Gandolfi attachment using sub‐mm small fragments and powder aggregates for various kinds of stony meteorites and develop a new analytical technique. We primarily focus on olivine and pyroxene because they are the most abundant and important minerals for stony meteorite classification. A new calibration is performed to estimate the FeO content of the olivine in unequilibrated ordinary chondrites, which is useful for determining the meteorite chemical group irrespective of powder aggregate diameter but dependent on fragment grain diameter. This is because X‐ray intensity absorption is more effective for grains than for powders. Clinoenstatite (Cen) and orthoenstatite (Oen) were distinguished using the presence or absence of the isolated Oen 511 index peak. The method is also applied to other stony meteorites including carbonaceous chondrites and achondrites. The XRD results are consistent with studies based on polished sections involving textural observations by scanning microscope and chemical compositions of the constituent minerals. The new measurement technique presented here is convenient because of its use in air by the laboratory‐based X‐ray diffractometer, which makes it useful for the initial analyses of restricted extraterrestrial sample characterization. 相似文献
26.
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
27.
In computer simulations based on creeping motion equations, the difference in stress sensitivity of strain rate between Newtonian rheology and non-Newtonian power-law rheology does not greatly influence the types of mantled porphyroclast developed in simple shear viscous flows. Porphyroclast type is determined by the radius of an initial spherical mantle. When a thin mantle lies within the separatrix, (δ2-objects develop at small γ, then complex porphyroclasts appear with increasing γ. When the mantle is thicker and transected by the separatrix, φ-objects form at small γ and δ2-objects appear with increasing γ during the same deformation. The transition from φ- to δ2-objects is gradual, the transition strain being dependent on the initial radius of the mantle. Our simulations did not produce θ-, δ1- or σ-objects. 相似文献
28.
The effect of swell on the drag coefficient, C
D, observed at the Hiratsuka Tower Station, presented by Suzuki et al. (1998, 2002), has been investigated. C
D increases sharply with the windsea Reynolds number, R
B, when there is a counter swell against the windsea direction, and only gradually when the swell comes from a mixture of directions.
In cases where 2-D wave spectra were unavailable (1998, and others), swells showed a scattering effect compared with the pure
windsea case on the C
D-R
B Diagram. R
B is a useful parameter for investigating the effect of swells and further systematic accumulation of appropriate data is needed. 相似文献
29.
This study reconstructed environmental changes to the seafloor associated with reclamation in Mishou Bay, Bungo Channel, Japan, based on measurements of sediment grain size, organic matter and sulfur contents of surface sediments and data from sediment cores. Grain size within sediment cores from the middle of Mishou Bay decreased from the beginning of the 1800s to the 1900s. In contrast, a grain size profile from the river mouth shows a gradual increase in grain size up through the sediment core. These changes in grain size indicate a decrease in tidal current velocity within the middle of the bay and that the delta system is gradually prograding from the river mouth. Records of organic matter composition and sulfur contents indicate that the effect of the river on seafloor sedimentation became stronger during the nineteenth century. These changes are related to reclamation during the late 1700s and 1800s. The decrease in sea area resulting from reclamation probably led to a decrease in tidal prism and current velocity. It is likely that the increasing effect of river water on sedimentation is associated with reclamation-related progradation of the river delta system. 相似文献