The Effect of Aggregation of Impurity Nitrogen on Diamond X-Ray Luminescence

Two samplings of 65 diamond crystals divided by the intensity of a slow X-ray luminescence component are studied from the Arkhangel’skaya and Karpinskogo-1 pipes. IR and EPR spectroscopies revealed a relationship between the nitrogen A and P2 centers of the diamonds and the presence of a slow X-ray luminescence component. Its absence in most diamonds with high content of P1 (C) centers is explained by the low number of A and P2 centers.     

Delineation of Rajmahal basaltic flows,inter-trappeans and associated coal layers using Audio-magneto-telluric method

The extensive volcanic activity of Rajmahal occurred during early Cretaceous (~117 Ma). Potentially perspective Gondawana sediments containing coal seam is partially covered by these basalts. Basalts as well as coal are already known to be of immense economic importance over Rajmahal traps. The present study mainly deals with delineation of basaltic lava flows and associated coal layers using the Audio-magneto-telluric (AMT) study in the south central region of Rajmahal traps near Suri, West Bengal, India. Initially, the field situations have been simulated using forward model with top alluvium cover followed by basaltic lava flows, a wedge shaped inter-trappean sedimentary formation with second basaltic lava flows and basement at the bottom. The model was constrained using available litholog. The model study reveals the presence of moderately resistive basalts, relatively conductive inter-trappeans and the basement, except the top alluvium layer and thin inter-trappeans. Subsequently, threeAMT sounding have been carried out over Cholaguria, Hatgacha and Pachami, Suri, West Bengal. The field AMT study reveals three basaltic lava flows with varying thickness from ~40m to ~350m and composite thickness of ~620m to ~640m, which match well with the published borehole litholog. The inter-trappeans have been identified at 500m to 620m, 310m to 400m and 500m to 640m depths over Cholaguria, Hatgacha and Pachami, respectively. It is interesting to mention that the identified inter-trappeans are inferred to be coal/shaly-coal which are matching very well with the published borehole lithologs.     

Main problems of water use and transfer of technology

Man and water are closely related in a dualistic manner: on one hand water has great influence on man's welfare and social development, on the other man's activities greatly affect water as such. Comparing the present and future water needs with water availability, the author concludes that some world regions should be considered as truly water scarce at least during the next generation. Man's activities create water problems which tend to change with time and exhibit a regional pattern. Many problems can be avoided if advance impact studies were made more regularly for planned water-related activities and projects. The author ends by stressing that differences in climate, hydrology, culture and dominating water problems tend to complicate the important process of transfer of knowledge between temperate and tropical countries.     

Minimum on the light curve of the classical symbiotic star AS 338 in 1999

We present our UBVRI photometry and spectroscopy of AS 338 performed in 1999–2000. Another eclipse of the hot component in this symbiotic binary system, the deepest one ever observed, occurred in September 1999. The U brightness declined by ～2^m, the Hβflux decreased by a factor of ～2.3, and the [O III]γ5007 flux did not change. The hot component is eclipsed at orbital phases ?≈0.045–0.057. The U-B color index begins to appreciably fluctuate during an eclipse of the hot component and its circumstellar envelope. About 100 days after a strong outburst of 1995, the mean UBV brightness of AS 338 declined linearly in the ensuing five years at the same rate in all bands (ΔU/Δt≈10^?3 mag/day). The brightness of the outer, uneclipsed parts of the circumstellar envelope also decreased, which is attributable to a reduction in the luminosity of the hot component against the rise in its temperature. The appearance of He II lines has not yet been recorded, though the optical brightness of AS 338 has already dropped by ～2^m after the outburst.     

Robe's restricted three-body problem with drag

Robe's restricted three-body problem is investigated with regards to the effects of a linear drag force. In particular. the stability of the model's equilibrium points is studied in this respect. Two scenarios are envisaged: the one originally discussed by Robe himself and the one suggested by him and recently analyzed by the present authors, that assumes for the fluid body the structure of a Roche's ellipsoid.     

Untersuchungen mit der Elektronen-Mikrosonde an zonargebauten Mineralen der Pyromorphitgruppe

Zusammenfassung Natürliche Glieder der Pyromorphitgruppe wurden mit einer Elektronen-Mikrosonde untersucht. Bei allen untersuchten Proben tritt gegenseitige isomorphe Ersetzung des Phosphors, Arsens oder Vanadins auf. Die fast reinen Endglieder zeigen dabei einen ziemlich gleichmäßigen, geringfügigen Einbau der Nebenkomponente unabhängig vom optischen Zonarbau, während für die Mischglieder starke zonare Schwankungen in der chemischen Zusammensetzung in Abhängigkeit von den optisch erkennbaren Zonen typisch sind.In einem Falle wird zonar Blei isomorph durch Kalzium ersetzt. Der Chlorgehalt scheint von keiner der übrigen Komponenten abhängig zu sein und unterliegt nur z.T. zonaren Schwankungen. Zonarbau durch Farbänderungen und Einbau von Fremdpartikeln, fast nur bei den Mischgliedern zu finden, bedingt zumeist entsprechende zonare chemische Veränderungen der Phosphor-, Arsen- oder Vanadingehalte. Zonarbau infolge unterschiedlicher optischer Orientierung kann sowohl ohne chemische Zonen vorkommen (bei den Endgliedern), als auch mit gleichlaufenden Veränderungen der Komponenten bei den Mischgliedern.Zonarbau als Folge unterschiedlicher optischer Orientierung, Felderteilung und Zweiachsigkeit haben nach den vorliegenden Untersuchungen nicht isomorphen Ersatz als Ursache; Veränderungen der physikalischen Bedingungen während oder Sekundärvorgänge nach Beendigung des Wachstums der Kristalle könnten eine Rolle gespielt haben. In Frage kommt auch eine Abweichung von der hexagonalen Symmetrie; eine kürzlich von U. Keppler (Karlsruhe) durchgeführte Einkristall-Untersuchung einer Mimetesit-Zone ergab für diese eine monokline Symmetrie (im Druck).Das Auftreten von diffusen Reflexen oder Doppellinien in den Röntgendiagrammen der Mischglieder kann zwanglos durch die gegenläufigen Schwankungen der Phosphor-, Arsen- oder Vanadin-Gehalte gedeutet werden.

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Electron microprobe investigation of members of the pyromorphite group with zoned structure

Natural members of the pyromorphite group, pyromorphite Pb₅(PO₄)₃Cl, mimetite Pb₅(AsO₄)₃Cl, kampylite Pb₅(PO₄, AsO₄)₃Cl, and vanadinite Pb₅(VO₄)₃Cl were investigated by the electron microprobe method. Mutual isomorphic replacement of P, V and As was observed even in the purest available end members occurring in nature. The frequently appearing zoned structure, observed in thin sections, may or may not coincide with corresponding chemical changes with respect to the V, As or P contents, mainly for the intermediate members, while for the rather pure end members nearly no connection was found between optical zones and chemical composition (also as to the division of basal sections into six triangular areas).

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Den Herren Prof. Dr. F. Laves, Zürich, und Prof. Dr. H. Wondratschek, Karlsruhe, danken wir für die Ermöglichung dieser Arbeit und für das fördernde Interesse. Der Deutschen Forschungsgemeinschaft danken wir für die finanzielle Unterstützung dieser Arbeit durch eine Beihilfe.