REPORT OF FIELD SURVEY IN KIRIMUN, KENYA, 1980

STUDY OF THE TERTIARY HOMINOINDS AND THEIR PALAEOENVIRONMENTS IN EAST AFRICA VOL.I1982 BY OSAKA UNIVERSITY This book is printed with the Grant-in-Aid of the Japanese Ministry of Education,Science and Culture(Project Number: 56043038/1981, 504141/1980

Surface Charge-Density Wave on the One-Dimensional Organic Conductor β-(BEDT-TTF)2PF6

We performed STM and theoretical studies of the surface of β-(BEDT-TTF)2PF6 which is known to show a metal-insulator transition at 297 K with the nesting vector of Qbulk = a*+0.5c* as a bulk phase. Two typical charge-density wave (CDW) phases with QS1 = 0.13a*+0.26c* and QS2 = 0.19a*+0.20c* were observed at 285 K on the surface. The observed structures were correlated well with the analysis of the susceptibility χ(Q), given the incomplete surface-charge transfer in the polar surface of this material. This is the first observation of surface CDW phases that reflect the characteristics of the electronic structure. These results suggest the possible discovery of other surface properties, such as surface superconductivity, in organic materials with a polar surface

X-ray Anomalous Scattering of Diluted Magnetic Oxide Semiconductors: Possible Evidence of Lattice Deformation for High Temperature Ferromagnetism

We have examined whether the Co ions crystallographically substitute on the Ti sites in rutile and anatase Ti_{1-x}$Co$_{x}$O$_{2-delta}$thin films that exhibit room-temperature ferromagnetism. Intensities of the x-ray Bragg reflection from the films were measured around the$K$-absorption-edge of Co. If the Co ions randomly substitute on the Ti sites, the intensity should exhibit an anomaly due to the anomalous dispersion of the atomic scattering factor of Co. However, none of the anatase and rutile samples did exhibit an anomaly, unambiguously showing that the Co ions in Ti$_{1-x}$Co$_{x}$O$_{2-delta}$are not exactly located at the Ti sites of TiO$_2$. The absence of the anomaly is probably caused by a significant deformation of the local structure around Co due to the oxygen vacancy. We have applied the same method to paramagnetic Zn$_{1-x}$Co$_{x}$O thin films and obtained direct evidence that the Co ions are indeed substituted on the Zn sites.Comment: 5 pages, 4 figures, accepted in PR

四国東部の四万十帯からの後期白亜紀アンモナイト

A Late Cretaceous ammonite was discovered from the lower section of the Mugi Melange of the Shimanto Belt in the Kusunoura area, Mugi, Tokushima Prefecture, Japan. The ammonite is identified with Gaudryceras cf. tombetsense reported from the K2 unit (Maastrichian) of the Krasnoyarka Formation, Makarov area, southern Sakhalin, Russia. The lower section of the Mugi Melange is assigned to the early Paleogene, based on a recently obtained U-Pb zircon age. It is reasonable to assume that the ammonite from the Kusunoura area was trapped as an exotic block within the lower section of the Mugi Melange.徳島県牟岐町楠之浦地域に分布する四万十帯牟岐メランジュ下部セクションより，後期白亜紀アンモナイトを発見した．このアンモナイトは，ロシア・サハリン南部マカロフ地域のクラスノヤルカ層の岩相ユニットK2（マストリヒチアン階）から報告されたGaudryceras cf. tombetsenseに最も似ている．最近のジルコンU-Pb年代に関する研究に従うと，牟岐メランジュ下部セクションの年代は古第三紀初頭を示す．現時点では，楠之浦地域から発見された後期白亜紀アンモナイトは，古第三紀堆積物である牟岐メランジュ下部セクションの中に外来岩塊として含まれたと考えるのが妥当である

Environment: Peculiar Pigment Cell Neoplasm in Fish

Chromatophoroma in the croaker (Nibea mitsukurii) showed a unique geographic distribution. The contribution of environmental chemicals to the cause of chromatophoroma in the feral croaker is considered likely on the basis of the following results in our studies. 1) Chromatophoroma was induced in tank-reared N. mitsukurii by administration of certain kinds of known carcinogens such as 7,12-dimethyl-benz(a)anthra-cene, N-methyl-N'-nitro-N-nitrosoguanidine, and nifurpirinol. 2) Local accumulation of pigment-cell hyperplasia in the catfish (Protosus anguillaris) showed similar tendencies to those of chromatophoroma in N. mitsukurii. 3) Removal of contaminated sediment from the harbor and the river appeared to reduce the incidence from 47% in 1973–1983 to about 20% in 1985–1987. 4) Waste water from a factory located at the station where the incidence of the neoplasm was the highest contained mutagenic substances such as chloroacetones and glyoxals [5]. Exposure of catfish to the waste water induced pigment-cell hyperplasia on the skin. J Invest Dermatol 92:248S–254S, 198

Phasons Formed on Si(100) Dimer Rows Observed by Scanning Tunneling Microscopy(STM-Si(100))

At～6K, dimers on Si(100) surface are buckled, and structural change occurs between c(4x2) and p(2x2) arrangements due to dimer flip-flop motion at phase boundaries on dimer rows. The phase defect appearing at boundaries has a structure similar to that of the type-C defect, two adjacent dimers are buckled in the same orientation. In consideration of the dimer arrangement around the phase boundary, there exist structures with two different conformations for the phase defect, however, according to the Ising spin model, both of which have the same energy higher compared to other buckled dimers with 2x anticorrelation along a dimer row. Therefore, dimer flip-flop motion at a phase boundary results in the migration of a solitary phase defect with higher energy, as a phason