Electrical conduction and polarization of calcite single crystals

The electrical conductivity and polarization properties of calcite single crystals with three orientations, namely, a (00.1) plane perpendicular to the crystallographic c axis (10.0) plane parallel to the crystallographic c axis, and a (10.4) cleavage plane, were studied by both complex impedance and thermally stimulated depolarization current (TSDC) measurements. Conductivities for (00.1)-, (10.0)-, and (10.4)-oriented single calcite crystals at 400–600?°C were 1.16?×?10^?7?–?1.05?×?10^?5, 7.40?×?10^?8?–?4.27?×?10^?6, and 4.27?×?10^?7?–?2.86?×?10^?5 Ω^?1 m^?1, respectively, and the activation energies for conduction were 112, 103, and 101?kJ?mol^?1, respectively. The TSDC spectra verified the electrical polarizability of calcite crystals. The activation energy for depolarization, estimated from TSDC spectra, of the (00.1)-, (10.0)-, and (10.4)-oriented calcite substrates were 112, 119, and 114?kJ?mol^?1, respectively. Considering the correlation between the processes of conduction and electric polarization, we proposed the mechanisms of conduction and polarization in calcite on the assumption of oxide ion transport.     

A quenched carbonaceous composite (QCC) grain model for the interstellar 220 NM extinction hump

The dependence of the wavelength of peak absorption of dust grains on the grain size is investigated analytically by using an oscillator model for the absorption band. The peak wavelength of a weak absorption band is much less sensitive to the grain size than that of a strong band. This is explained by the fact that the surface mode, which is excited in the strong absorption band, is not raised in the weak absorption band. A quenched carbonaceous composite (QCC) synthesized from hydrocarbon plasma is found to have a weak absorption band at 220 nm. The absorption peak wavelength of the QCC grains falls well in the range of 217±7 nm even if the grain size runs from 5 to 100 nm. This is compatible with the observed constancy of the 220 nm hump (217±5 nm). By contrast, the absorption peak of graphite grains, which have a strong band around 280 nm and have been investigated as candidates for the hump, is very sensitive to the grain size. A quite narrow range of the grain size is required to account for the observed 220 nm feature. A weak absorption model, such as the QCC grains, is suggested to be a more likely candidate for the 220 nm extinction hump than a strong absorption model, such as graphite grains.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.     

Possible solar neutron events recorded by the ground-based neutron monitor

Solar Physics - Possible solar neutron emission associated with five SMM gamma-ray events on 7 June 1980, 21 June 1980, 6 November 1980, 26 November 1982 and 25 April 1984 was found from analysis...     

The infrared and ultraviolet absorptions of micro-organisms and their relation to the Hoyle-Wickramashinghe hypothesis

Absorption of yeast andE. coli in the infrared and ultraviolet regions and that of diatomaceous soil in the infrared region have been obtained. Electron microscope photographs of aggregates ofE. coli have also been obtained. These results are discussed in relation to the Hoyle-Wickramasinghe hypothesis regarding the nature of interstellar grains.Department of Nuclear Engineering     

Errors in response calculations for beams

When the finite element method is used to idealize a structure, its dynamic response can be determined from the governing matrix equation by the normal mode method or by one of the many approximate direct integration methods. In either method the approximate data of the finite element idealization are used, but further assumptions are introduced by the direct integration scheme. It is the purpose of this paper to study these errors for a simple structure. The transient flexural vibrations of a uniform cantilever beam, which is subjected to a transverse force at the free end are determined by the Laplace transform method. Comparable responses are obtained for a finite element idealization of the beam, using the normal mode and Newmark average acceleration methods; the errors associated with the approximate methods are studied. If accuracy has priority and the quantity of data is small, the normal mode method is recommended; however, if the quantity of data is large, the Newmark method is useful.     

Nonlinear interaction of the Tsugaru Warm Current and tide in the Tsugaru Strait

The Tsugaru Strait, which connects the Sea of Japan with the Pacific Ocean, is characterized by the eastward Tsugaru Warm Current (TWC) and oscillating tidal currents of similar magnitude. A 15-day current observation was conducted in one of the two narrow channels in the strait, at the northwest tip of the Shimokita Peninsula. The observation revealed that the spectral energy of the semidiurnal current exceeds that of the diurnal current, contrary to the conventional view. The Tsugaru Strait regional model was developed to study the mechanism of this spectral energy reversal (140–141.5° E, 40.4–42.6° N, 500?m grid resolution). At the eastern and western open boundaries, the model was driven by the constant Tsugaru warm current and tidal elevation, which was adjusted by comparing the model with tidal gauge observations within the channel. The relative magnitude of the spectral energies differed from that of the observation when the model was driven by tide only. However, the spectral energy levels were reversed when the model was driven by both tide and current. The nonlinear interaction of periodic tidal currents and the steady TWC was explained by the vorticity equation, which describes the production and advection of residual currents from tidal currents. According to the model results, flow separation and advection of vorticity by the TWC was the most prominent factor in this phenomenon. Because of the strong nonlinearities, flow separation around the headland occurred during the tidal period with dominant current magnitude and furnished the main difference between the diurnal and semidiurnal interactions. These phenomena were enhanced by the complex topography, and demonstrate the importance of scale interaction, especially when developing high-resolution regional models.     

Geology and age model of the Lower Pleistocene Nojima,Ofuna, and Koshiba Formations of the middle Kazusa Group,a forearc basin‐fill sequence on the Miura Peninsula,the Pacific side of central Japan

We present field and core observations, nannofossil biostratigraphy, and stable oxygen isotope fluctuations in foraminiferal tests to describe the geology and to construct an age model of the Lower Pleistocene Nojima, Ofuna, and Koshiba Formations (in ascending order) of the middle Kazusa Group, a forearc basin‐fill succession, exposed on the northern Miura Peninsula on the Pacific side of central Japan. In the study area, the Nojima Formation is composed of sandy mudstone and alternating sandy mudstone and mudstone, the Ofuna Formation of massive mudstone, and the Koshiba Formation of sandy mudstone, muddy sandstone, and sandstone. The Kazusa Group contains many tuff beds that are characteristic of forearc deposits. Thirty‐six of those tuff beds have characteristic lithologies and stratigraphic positions that allow them to be traced over considerable distances. Examination of calcareous nannofossils revealed three nannofossil datum planes in the sequences: datum 10 (first appearance of large Gephyrocapsa), datum 11 (first appearance of Gephyrocapsa oceanica), and datum 12 (first appearance of Gephyrocapsa caribbeanica). Stable oxygen isotope data from the tests of the planktonic foraminifer Globorotalia inflata extracted from cores were measured to identify the stratigraphic fluctuations of oxygen isotope ratios that are controlled by glacial–interglacial cycles. The observed fluctuations were assigned to marine isotope stages (MISs) 49–61 on the basis of correlations of the fluctuations with nannofossil datum planes. Using the age model obtained, we estimated the ages of 24 tuff beds. Among these, the SKT‐11 and SKT‐12 tuff beds have been correlated with the Kd25 and Kd24 tuff beds, respectively, of the Kiwada Formation on the Boso Peninsula. The Kd25 and Kd24 tuff beds are widely recognized in Pleistocene strata in Japan. We used our age model to date SKT‐11 at 1573 ka and SKT‐12 at 1543 ka.     

双壳类软体动物的水产遗传学研究进展

双壳类是水产养殖业中非常重要的养殖贝类,在世界范围其产量日益增长。作者综述了近年来双壳类遗传学研究进展,包括遗传变异、数量遗传、选种育种、杂交育种、染色体及分子遗传学等领域的最新研究进展。     

The ultraviolet spectra of thin evaporated films of carbonaceous chondrite

Absorption spectra in the visible to the near ultraviolet were measured on the Belgica chondrite B-7904 in a form of thin solid film made by the vacuum evaporation. The spectra obtained exhibit a sharp peak at 226 nm and a broad bump around 280nm. These features were found arising from the meteorite component FeS (troilite). The peak at 226 nm shows a doublet structure with the band-width considerably narrower than the 217.5 nm feature in the interstellar extinction. The absorption spectra obtained previously with the pulverized chondrites suspended in a liquid were also found reproducible by the pulverized FeS.Sponsored by the Office of Health and Environmental Research, U.S. Department of Energy under contract DE-AC05-840R21400 with Martin Marietta Energy Systems, Inc.