Density measurements of liquid Fe–Si alloys at high pressure using the sink–float method     

Ryuji Tateyama  Eiji Ohtani  Hidenori Terasaki  Keisuke Nishida  Yuki Shibazaki  Akio Suzuki  Takumi Kikegawa 《Physics and Chemistry of Minerals》2011,38(10):801-807

The compositional dependence on the density of liquid Fe alloys under high pressure is important for estimating the amount of light elements in the Earth’s outer core. Here, we report on the density of liquid Fe–Si at 4 GPa and 1,923 K measured using the sink–float method and our investigation on the effect of the Si content on the density of the liquid. Our experiments show that the density of liquid Fe–Si decreases from 7.43 to 2.71 g/cm³ non-linearly with increasing Si content (0–100 at%). The molar volume of liquid Fe–Si calculated from the measured density gradually decreases in the compositional range 0–50 at% Si, and increases in the range 50–100 at% Si. It should be noted that the estimated molar volume of the alloys shows a negative volume of mixing between Fe and Si. This behaviour is similar to Fe–S liquid (Nishida et al. in Phys Chem Miner 35:417–423, 2008). However, the excess molar volume of mixing for the liquid Fe–Si is smaller than that of liquid Fe–S. The light element contents in the outer core estimated previously may be an underestimation if we take into account the possible negative value of the excess mixing volume of iron–light element alloys in the outer core.  相似文献   

The self-thinning exponent in overcrowded stands of the mangrove, Kandelia obovata, on Okinawa Island, Japan     

Mouctar Kamara  Rashila Deshar  Sahadev Sharma  Md. Kamruzzaman  Akio Hagihara 《Journal of Oceanography》2012,68(6):851-856

Weller??s allometric model assumes that the allometric relationships of mean area occupied by a tree $ \bar{s} $ , i.e., the reciprocal of population density $ \rho $ , $ \bar{s}\left( { = {1 \mathord{\left/ {\vphantom {1 {\rho = g_{\varphi } \cdot \bar{w}^{\varphi } }}} \right. \kern-0em} {\rho = g_{\varphi } \cdot \bar{w}^{\varphi } }}} \right) $ , mean tree height $ \bar{H}\left( { = g_{\theta } \cdot \bar{w}^{\theta } } \right) $ , and mean aboveground mass density $ \bar{d}\left( { = g_{\delta } \cdot \bar{w}^{\delta } } \right) $ to mean aboveground mass $ \bar{w} $ hold. Using the model, the self-thinning line $ \left( {\bar{w} = K \cdot \rho^{ - \alpha } } \right) $ of overcrowded Kandelia obovata stands in Okinawa, Japan, was studied over 8?years. Mean tree height increased with increasing $ \bar{w} $ . The values of the allometric constant $ \theta $ and the multiplying factor $ g_{\theta } $ are 0.3857 and 2.157?m?kg^???, respectively. The allometric constant $ \delta $ and the multiplying factor $ g_{\delta } $ are ?0.01673 and 2.685?m^?3?kg^1???, respectively. The $ \delta $ value was not significantly different from zero, showing that $ \bar{d} $ remains constant regardless of any increase in $ \bar{w} $ . The average of $ \bar{d} $ , i.e., biomass density $ \left( {{{\bar{w} \cdot \rho } \mathord{\left/ {\vphantom {{\bar{w} \cdot \rho } {\bar{H}}}} \right. \kern-0em} {\bar{H}}}} \right) $ , was 2.641?±?0.022?kg?m^?3, which was considerably higher than 1.3?C1.5?kg?m^?3 of most terrestrial forests. The self-thinning exponent $ \alpha \left( { = {1 \mathord{\left/ {\vphantom {1 {\varphi = }}} \right. \kern-0em} {\varphi = }}{1 \mathord{\left/ {\vphantom {1 {\left\{ {1 - \left( {\theta + \delta } \right)} \right\}}}} \right. \kern-0em} {\left\{ {1 - \left( {\theta + \delta } \right)} \right\}}}} \right) $ and the multiplying factor $ K\left( { = \left( {g_{\theta } \cdot g_{\delta } } \right)^{\alpha } } \right) $ were estimated to be 1.585 and 16.18?kg?m^?2??, respectively. The estimators $ \theta $ and $ \delta $ are dependent on each other. Therefore, the observed value of $ \theta + \delta $ cannot be used for the test of the hypothesis that the expectation of the estimator $ \theta + \delta $ equals 1/3, i.e., $ \alpha = {3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-0em} 2} $ , or 1/4, i.e., $ \alpha = {4 \mathord{\left/ {\vphantom {4 3}} \right. \kern-0em} 3} $ . The $ \varphi $ value was 0.6310, which is the same as the reciprocal of the self-thinning exponent of 1.585, and was not significantly different from 2/3 (t?=?1.860, df?=?191, p?=?0.06429), i.e., $ \alpha = {3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-0em} 2} $ . Thus the self-thinning exponent is not significantly different from 3/2 based on the simple geometric model. On the other hand, the self-thinning exponent was significantly different from 3/4 (t?=?6.213, df?=?191, p?=?3.182?×?10^?9), i.e., $ \alpha = {4 \mathord{\left/ {\vphantom {4 3}} \right. \kern-0em} 3} $ . Therefore, the self-thinning exponent is significantly different from 4/3 based on the metabolic model.  相似文献   

A Monte Carlo simulation of the intergalactic absorption and the detectability of the Lyman continuum from distant galaxies     

Akio K. Inoue  Ikuru Iwata 《Monthly notices of the Royal Astronomical Society》2008,387(4):1681-1692

We have made a Monte Carlo simulation of the intergalactic absorption in order to model the Lyman continuum absorption, which is required to estimate the escape fraction of the Lyman continuum from distant galaxies. To input into the simulation, we derive an empirical distribution function of the intergalactic absorbers which reproduces recent observational statistics of the Lyman α forest, Lyman limit systems (LLSs) and damped Lyman α systems (DLAs) simultaneously. In particular, we assume a common functional form of the number evolution along the redshift for all types of absorbers. The Lyman series transmissions in our simulation reproduce the observed redshift evolution of the transmissions excellently, and the Lyman continuum transmission also agrees with an observed estimation which is still quite rare in the literature. The probability distribution of the Lyman α opacity in our simulation is lognormal with a tail towards a large opacity. This tail is produced by DLAs. The probability distribution of the Lyman continuum opacity in our simulation also shows a broad tail towards a large opacity. This tail is produced by LLSs. Because of the rarity of LLSs, we have a chance to have a clean line of sight in the Lyman continuum even for   z ∼ 4  with a probability of about 20 per cent. Our simulation expects a good correlation between the Lyman continuum opacity and the Lyman α opacity, which may be useful to estimate the former from the latter for an individual line of sight.  相似文献   

East Asian summer monsoon simulation by a 20-km mesh AGCM   总被引：1，自引：0，他引：1  

Akio Kitoh  Shoji Kusunoki 《Climate Dynamics》2008,31(4):389-401

East Asian summer monsoon climate simulated by a global 20-km mesh atmospheric general circulation model (AGCM) forced by the global sea surface temperature during the period 1979–1998 is investigated. In comparison with a lower resolution (180-km mesh) model experiment, it is revealed that the 20-km mesh AGCM shows the superiority in simulating orographic rainfall not only its location but also its amount. The Baiu frontal structure is also better simulated in the higher resolution model, which leads to stronger Baiu rainfall. The 20-km model also shows more intense extremes in precipitation. Interannual variability of June–August mean precipitation and seasonal march of the monsoon rain band are also investigated. This paper is a contribution to the AMIP-CMIP Diagnostic Sub-project on General Circulation Model Simulation of the East Asian Climate, coordinated by W.-C. Wang.  相似文献   

Phylogeny and phylogeography of the land hermit crab Coenobita purpureus (Decapoda: Anomura: Coenobitidae) in the Northwestern Pacific Region          下载免费PDF全文

Katsuyuki Hamasaki  Chikako Iizuka  Tetsuya Sanda  Hideyuki Imai  Shuichi Kitada 《Marine Ecology》2017,38(1)

Hermit crabs of the family Coenobitidae comprise the land hermit crabs, with 16 Coenobita species, and the coconut crab Birgus latro. They are terrestrial but spend their marine life as planktonic larvae. Some coenobitid crabs are widely distributed in the Indo‐West Pacific region, and some species occupy narrower ranges. To improve our knowledge of coenobitid crab speciation and geographical distribution patterns, we examined the phylogenetic relationship between Coenobita purpureus, which has a narrow distribution in the Northwestern Pacific, and its more widely distributed coenobitids including B. latro, Coenobita brevimanus, Coenobita cavipes, Coenobita perlatus, Coenobita rugosus and Coenobita violascens based on the mtDNA cytochrome c oxidase subunit I (COI) and 16S rDNA genes. We also assessed the phylogeography of Co. purpureus populations based on the COI gene. Our phylogenetic and phylogeographical analyses revealed that (i) Co. purpureus clustered with Co. rugosus and (ii) the Co. purpureus population in the Ogasawara Islands was genetically distinct from those in other regions, which showed genetic panmixia. It has been hypothesized that Co. purpureus evolved in the isolated landmasses of the Ryukyu region during the Pliocene, and that its population expanded and colonized the Ogasawara Islands in the late Pleistocene. Further phylogeographical studies on Coenobita species with relatively narrow distributions coupled with characterization of their phylogenetic relationships with widely distributed congeners will advance our knowledge of the speciation and geographical distribution history of coenobitid crabs.  相似文献   

Horizontal distribution of calanoid copepods in the western Arctic Ocean during the summer of 2008   总被引：1，自引：1，他引：0  

Kohei Matsuno  Atsushi Yamaguchi  Koji Shimada  Ichiro Imai 《Polar Science》2012,6(1):105-119

The horizontal distribution of the epipelagic zooplankton communities in the western Arctic Ocean was studied during August–October 2008. Zooplankton abundance and biomass were higher in the Chukchi Sea, and ranged from 3,000 to 274,000 ind. m^?2 and 5–678 g WM m^?2, respectively. Copepods were the most dominant taxa and comprised 37?94% of zooplankton abundance. For calanoid copepods, 30 species belonging to 20 genera were identified. Based on the copepod abundance, their communities were classified into three groups using a cluster analysis. The horizontal distribution of each group was well synchronized with depth zones, defined here as Shelf, Slope and Basin. Neritic Pacific copepods were the dominant species in the Shelf zone. Arctic copepods were substantially greater in the Slope zone than the other regions. Mesopelagic copepods were greater in the Basin zone than the other regions. Stage compositions of large-sized Arctic copepods (Calanus glacialis and Metridia longa) were characterized by the dominance of late copepodid stages in the Basin. Both the abundance and stage compositions of large copepods corresponded well with Chl. a concentrations in each region, with high Chl. a in the Shelf and Slope supporting reproduction of copepods resulting in high abundance dominated by early copepodid stages.  相似文献   

Geology and Skarn Cu–Bi–Au Mineralization at Shwe Min Bon Area,Kalaw Township,Southern Shan State,Myanmar     

Nyein N. Sint  Kotaro Yonezu  Thomas Tindell  May T. Aye  Htay Win  Akira Imai  Koichiro Watanabe 《Resource Geology》2019,69(1):85-106

The Shwe Min Bon Cu–Au skarn deposit lies within one of the largest Au–Cu belts in Myanmar. The deposit is situated along the Shan scarp zone, which marks the boundary between the Myanmar central basin to the west and the Shan plateau to the east. The Shwe Min Bon deposit comprises skarn‐type metasomatic alteration, and the Cu–Au mineralization occurs along the contact face between the Nwabangyi Dolomite and Shweminbon Formation and the Cretaceous dioritic rocks. The metasomatic process resulted in pro‐ and retrograde mineral assemblages in exoskarn. Hydrothermal activities in the Shwe Min Bon deposit are classified into prograde, retrograde stage I, and retrograde stage II. The prograde skarn is classified into a proximal garnet skarn with minor clinopyroxene and a distal wollastonite skarn. Chlorite, epidote, and tremolite–actinolite were formed during the retrograde stage I. Cu–Au mineralization mainly occurred in retrograde stage I, which was characterized by moderate temperatures (260–320 °C) and fluid with a moderate salinity (5.0–6.0% NaCl equiv.). Low temperature (180–200 °C) and low salinity (2.0–3.0% NaCl equiv.) were responsible for retrograde stage II. Au mineralization is mainly associated with chalcopyrite and tennantite in retrograde stage I and with tellurobismuthite in retrograde stage II.  相似文献   

Geology,Alteration, and Mineralization of the Kay Tanda Epithermal Gold Deposit,Lobo, Batangas,Philippines     

Sofia Marah P. Frias  Akira Imai  Ryohei Takahashi  Ma. Ines Rosana Balangue‐Tarriela  Carlo Arcilla  Nigel Blamey 《Resource Geology》2019,69(4):351-384

The Kay Tanda epithermal Au deposit in Lobo, Batangas is one of the Au deposits situated in the Batangas Mineral District in southern Luzon, Philippines. This study aims to document the geological, alteration, and mineralization characteristics and to determine the age of the mineralization, the mechanism of ore deposition, and the hydrothermal fluid characteristics of the Kay Tanda deposit. The geology of Kay Tanda consists of (i) the Talahib Volcanic Sequence, a Middle Miocene dacitic to andesitic volcaniclastic sequence that served as the host rock of the mineralization; (ii) the Balibago Diorite Complex, a cogenetic intrusive complex intruding the Talahib Volcanic Sequence; (iii) the Calatagan Formation, a Late Miocene to Early Pliocene volcanosedimentary formation unconformably overlying the Talahib Volcanic Sequence; (iv) the Dacite Porphyry Intrusives, which intruded the older lithological units; and (v) the Balibago Andesite, a Pliocene postmineralization volcaniclastic unit. K‐Ar dating on illite collected from the alteration haloes around quartz veins demonstrated that the age of mineralization is around 5.9 ± 0.2 to 5.5 ± 0.2 Ma (Late Miocene). Two main styles of mineralization are identified in Kay Tanda. The first style is an early‐stage extensive epithermal mineralization characterized by stratabound Au‐Ag‐bearing quartz stockworks hosted at the shallower levels of the Talahib Volcanic Sequence. The second style is a late‐stage base metal (Zn, Pb, and Cu) epithermal mineralization with local bonanza‐grade Au mineralization hosted in veins and hydrothermal breccias that are intersected at deeper levels of the Talahib Volcanic Sequence and at the shallower levels of the Balibago Intrusive Complex. Paragenetic studies on the mineralization in Kay Tanda defined six stages of mineralization; the first two belong to the first mineralization style, while the last four belong to the second mineralization style. Stage 1 is composed of quartz ± pyrophyllite ± dickite/kaolinite ± diaspore alteration, which is cut by quartz veins. Stage 2 is composed of Au‐Ag‐bearing quartz stockworks associated with pervasive illite ± quartz ± smectite ± kaolinite alteration. Stage 3 is composed of carbonate veins with minor base metal sulfides. Stage 4 is composed of quartz ± adularia ± calcite veins and hydrothermal breccias, hosting the main base metal and bonanza‐grade Au mineralization, and is associated with chlorite‐illite‐quartz alteration. Stage 5 is composed of epidote‐carbonate veins associated with epidote‐calcite‐chlorite alteration. Stage 6 is composed of anhydrite‐gypsum veins with minor base metal mineralization. The alteration assemblage of the deposit evolved from an acidic mineral assemblage caused by the condensation of magmatic volatiles from the Balibago Intrusive Complex into the groundwater to a slightly acidic mineral assemblage caused by the interaction of the host rocks and the circulating hydrothermal waters being heated up by the Dacite Porphyry Intrusives to a near‐neutral pH toward the later parts of the mineralization. Fluid inclusion microthermometry indicates that the temperature of the system started to increase during Stage 1 (T = 220–250°C) and remained at high temperatures (T = 250–290°C) toward Stage 6 due to the continuous intrusion of Dacite Porphyry Intrusives at depth. Salinity slightly decreased toward the later stages due to the contribution of more meteoric waters into the hydrothermal system. Boiling is considered the main mechanism of ore deposition based on the occurrence of rhombic adularia, the heterogeneous trapping of fluid inclusions of variable liquid–vapor ratios, the distribution of homogenization temperatures, and the gas ratios obtained from the quantitative fluid inclusion gas analysis of quartz. Ore mineral assemblage and sulfur fugacity determined from the FeS content of sphalerite at temperatures estimated by fluid inclusion microthermometry indicate that the base metal mineralization at Kay Tanda evolved from a high sulfidation to an intermediate sulfidation condition.  相似文献   

Monitoring of DSP toxins in small-sized plankton fraction of seawater collected in Mutsu Bay,Japan, by ELISA method: relation with toxin contamination of scallop     

Imai I  Sugioka H  Nishitani G  Mitsuya T  Hamano Y 《Marine pollution bulletin》2003,47(1-6):114-117

Monitorings were conducted on DSP toxins in mid-gut gland of scallop (mouse assay), cell numbers of toxic dinoflagellate species of Dinophysis, and diarrhetic shellfish poisoning (DSP) toxins in small-sized (0.7-5 microm) plankton fraction of seawater collected from surface (0 m) and 20 m depth at a station in Mutsu Bay, Aomori Prefecture, Japan, in 2000. A specific enzyme-linked immunosorbent assay (ELISA) was employed for the analysis of DSP toxins in small-sized plankton fraction using a mouse monoclonal anti-okadaic acid antibody which recognizes okadaic acid, dinophysistoxin-1, and dinophysistoxin-3. DSP toxins were detected twice in the mid-gut gland of scallops at 1.1-2.3 MU (mouse units) g(-1) on 26 June and at 0.6-1.2 MU g(-1) on 3 July, respectively. Relatively high cell densities of D. fortii were observed on 26 June and 11 September, and may only contribute to the bivalve toxicity during late June to early July. D. acuminata did not appear to be responsible for the toxicity of scallops in Mutsu Bay in 2000. ELISA monitoring of small-sized plankton fraction in seawater could detect DSP toxins two weeks before the detection of the toxin in scallops, and could do so two weeks after the loss of the bivalve toxicity by mouse assay. On 17 July, toxic D. fortii was detected at only small number, <10 cells l(-1), but DSP toxins were detected by the ELISA assay, suggesting a presence of other toxic small-sized plankton in seawater. For the purpose of reducing negative impacts of DSP occurrences, monitorings have been carried out hitherto on DSP toxins of bivalve tissues by mouse assay and on cell densities of "toxic" species of Dinophysis. Here we propose a usefulness of ELISA monitoring of plankton toxicity, especially in small-sized fraction, which are possible foods of mixotrophic Dinophysis, as a practical tool for detecting and predicting DSPs in coastal areas of fisheries grounds of bivalve aquaculture.  相似文献   

The Preparation and Preliminary Characterisation of Four New Geological Survey of Japan Geochemical Reference Materials: Soils, JSO-1 and JSO-2; and Marine Sediments, JMS-1 and JMS-2   总被引：1，自引：0，他引：1  

Shigeru Terashima  Noboru Imai  Masahiro Taniguchi  Takashi Okai  Akira Nishimura 《Geostandards and Geoanalytical Research》2002,26(1):85-94

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