Differences in the acute toxicities of tributyltin between the Caprellidea and the Gammaridea (Crustacea: Amphipoda)     

Ohji M  Takeuchi I  Takahashi S  Tanabe S  Miyazaki N 《Marine pollution bulletin》2002,44(1):16-24

Tests for the acute toxicity of tributyltin (TBT) were conducted on amphipod crustaceans collected from Otsuchi Bay, Japan. Five species of caprellids and three species of gammarids, which belong to a closely related ecological niche, were used for the exposure experiments at seven test concentrations (0, 0.001, 0.01, 0.1, 1, 10 and 100 microg TBTCl/l) for 48 h at 20 degrees C. The 48-h LC50 values of the caprellids were 1.2-6.6 microg TBTCl/l, and these were significantly lower than those of the gammarids (17.8-23.1 microg TBTCl/l). This suggests that caprellids are more sensitive to TBT than gammarids. Furthermore, the proportions of TBT and its derivatives, dibutyltin (DBT) and monobutyltin (MBT), were measured in the amphipods collected from Otsuchi Bay. In the caprellids, TBT was the predominant compound, accounting for 72% of the total butyltin which reflected the butyltin ratio in seawater, while in the gammarids, TBT's breakdown products (DBT and MBT) predominated, accounting for 75% of the total butyltin. This difference suggests that caprellids may have lower metabolic capacity to degrade TBT than gammarids. Therefore, the difference in sensitivity to TBT among the amphipods is thought to be related to the species-specific capacity to metabolize TBT.  相似文献   

Morphological study of the solar granulation     

Reizaburo Kitai  Ichiro Kawaguchi 《Solar physics》1979,64(1):3-12

High resolution images of the solar granulation show the presence of the small dot-like dark regions in the granulation cells. From the study of the characteristics of these dark regions, it is found that the dark regions are formed without any relations to the presence of the magnetic field. Moreover, it is observed that a granulation cell splits in a few minutes after the formation of the dark regions in the cell. Similarities and differences between the granules with the dark regions and the so-called exploding granules are discussed.  相似文献   

Measurements of mantle wave velocities and inversion for lateral heterogeneity and anisotropy – II. Analysis by the single-station method     

Ichiro Nakanishi  Don L. Anderson 《Geophysical Journal International》1984,78(2):573-617

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⁴⁰Ar–³⁹Ar analysis of phlogopite in the Horoman Peridotite Complex, Hokkaido, Japan and implications for its origin     

Ichiro Kaneoka  Natsuko Takahashi and  Shoji Arai 《Island Arc》2001,10(1):22-32

Abstract ⁴⁰Ar–³⁹Ar analysis of phlogopite separated from a plagioclase lherzolite of the Horoman Peridotite Complex, Hokkaido, Japan, has yielded a plateau age of 20.6 ± 0.5 Ma in an environment where the metamorphic fluid was characterized by an almost atmospheric Ar isotopic ratio. The age spectrum is slightly saddle-shaped, implying some incorporation of excess ⁴⁰Ar during the formation of the phlogopite at a depth. As the phlogopite has been inferred to have formed in veins and/or interstitials during exhumation of the peridotite body, metasomatic fluids, to which ground- and sea water might have contributed, were probably involved in the formation of phlogopite in the crustal environment. A total ⁴⁰Ar–³⁹Ar age of 129 Ma of a whole rock sample of the plagioclase lherzolite, from which the phlogopite was separated and is representative of the main lithology of the Horoman Peridotite Complex, indicates the occurrence of excess ⁴⁰Ar. Hence, the age has no geological meaning.  相似文献   

Optimal displacement feedback control law for active tuned mass damper     

Ichiro Nagashima 《地震工程与结构动力学》2001,30(8):1221-1242

Optimal displacement feedback control law is derived for a vibration control of a single‐degree‐of‐freedom structure with an active tuned mass damper (ATMD). Analytical expressions of the linear quadratic regulator (LQR) feedback gains for the ATMD are derived by solving the Ricatti equation straightforwardly. Based on these solutions, it is found that if the stiffness of the tuned mass damper (TMD) is calibrated to satisfy a certain condition, the control law is simplified to be composed of the feedback gains only for the displacement of the structure and the velocity of the auxiliary mass stroke, which is referred to as ‘optimal displacement feedback control’. The mean‐square responses of the structure as well as the auxiliary mass against Gaussian white noise excitations are evaluated by solving the Lyapunov equation analytically based on the stochastic optimal control theory. Using these analytical solutions, the optimal damping parameter for the auxiliary mass is also derived. Finally, the optimal displacement feedback control law is presented. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Structure of Brazil twin boundaries in amethyst showing brewster fringes     

Lu Taijing  Ichiro Sunagawa 《Physics and Chemistry of Minerals》1990,17(3):207-211

Optical investigations of Brewster fringes in natural amethyst crystals have indicated that the fringes are Brazil twin boundaries consisting of McLaren and Pitkethly type zig-zag structures and closed parallelograms. The two types of Brazil twin boundaries appear alternately in the successive fringes and in different orientations in one fringe. The Brewster fringes develop by a process of incorporation of many Brazil twin lamellae, when growth conditions are stabilized after this process. If perturbation occurs in growth conditions, distinct growth banding with and without Brazil twin lamellae will develop, and not Brewster fringes.  相似文献   

Rectangular parallellepiped resonance method for piezoelectric crystals and elastic constants of alpha-quartz     

Ichiro Ohno 《Physics and Chemistry of Minerals》1990,17(5):371-378

A theory is presented on the free osculations of a rectangular parallelepiped of piezoelectric crystal, by extending the theory of the rectangular parallelepiped resonance (RPR) method to determine elastic constants of crystals, as exemplified by an alpha-quartz specimen. The piezoelectric contribution to resonance frequencies was examined numerically on the specimen, and it was revealed that piezoelectricity causes approximately 5 kHz increase around 1 MHz. The resonance frequencies of the specimen were measured and inverted to elastic constants by least squares inversion. The inversion was by both the previous non-piezoelectric or elastic theory and by the present piezoelectric theory. The use of the non-piezoelectric theory resulted in an overestimate of 2σ or 0.6% in c ₁₁ and underestimate of σ or 6% in c ₁₂. These are the constants expected to be most affected by piezoelectricity. Errors are less than σ in the other constants. During measurement, it was found that the force applied to hold the specimen caused deviations from free oscillation and experimental errors of 5 kHz. The correction for this force is of some importance in RPR studies of piezoelectric crystals.  相似文献   

Thermal phase transition of potassium sulfate,K2SO4     

Michihiro Miyake  Ichiro Minato  Shin-ichi Iwai 《Physics and Chemistry of Minerals》1979,4(4):307-315

The thermal phase transition of K₂SO₄ has been investigated by high temperature polarized light microscopy. K₂SO₄ undergoes a first-order transition at 587° C where the orthorhombic low temperature form (Pmcn) transforms into a hexagonal high temperature modification (P6₃/mmc). Prior to the beginning of the phase transition, K₂SO₄ shows an anomalous optical behavior. The crystal apparently becomes optically uniaxial twice at 338° and 425° C, respectively, and truly optically uniaxial at 587° C. The phase transition propagates through an intermediate temperature form, which is sandwiched between the low and the high temperature forms and moves in a definite direction, 〈130〉 (orthorhombic indices), in the vicinity of the phase transition. Passing through the phase transition point on cooling, dark belts crossing each other are observed which are a result of the transformation twins parallel to {110} and {130}.  相似文献   

X-ray topographic study of quartz crystals twinned according to japan twin law     

Toshikazu Yasuda  Ichiro Sunagawa 《Physics and Chemistry of Minerals》1982,8(3):121-127

Quartz crystals twinned according to Japan twin law were investigated by means of X-ray topography in order to understand the origin of characteristic morphology of twin crystals. It is demonstrated that the flattened and elongated morphology characteristic of quartz twins is due to preferential growth at twin junctions where dislocations with the Burgers vector direction 〈11 \(\overline {\text{2}} \) 1〉 concentrate, and that such preferential growth operates only when {10 \(\overline {\text{1}} \) 1} faces meet at the twin junction. Once {10 \(\overline {\text{1}} \) 0} faces appear at the twin junction due to the change of growth conditions, the effect diminishes sharply and the characteristic morphology becomes less pronounced. This leads to the conclusion that the characteristic morphology of quartz crystals twinned according to Japan twin law is formed at the earlier stage of growth and becomes less pronounced at the later stage of growth.  相似文献   

Rare gas isotopes and mass fractionation: An indicator of gas transport into or from a magma     

Ichiro Kaneoka 《Earth and Planetary Science Letters》1980,48(2):284-292

A simple model of mass fractionation may explain the isotopic ratios of rare gases in volcanic materials. Single-stage mass fractionation of atmospheric rare gases predicts an upper limit for²⁰Ne/²²Ne of 10.3 and a lower limit for⁴⁰Ar/³⁶Ar of 280. The rare gas data in volcanic materials seem to support this interpretation.Relatively low⁴⁰Ar/³⁶Ar ratios, as low as 282, have been observed in recent Japanese volcanic rocks. Such a low⁴⁰Ar/³⁶Ar ratio may be explained by mass fractionation of the atmospheric value if the rare gases represent those which were transported into the magma chamber with other volatile elements.Both the amounts and the fractionated rare gas abundance pattern of lighter elements which are observed in pumices from the recent eruption of Mt. Usu, Southern Hokkaido, Japan, suggest the possibility of air injection into its magma chamber. Thus, the fractionation of rare gases in volcanic materials may be a common occurrence, and it must be considered in models for the origin of isotopic differences between rare gases in volcanic materials and the atmosphere.  相似文献