C. Monty - Böcker

This volume is the proceedings of the NATO Advanced Study Institute, "Diffusion in Materials", held at "Centre Paul Langevin", Aussois, during March 12-25, 1989. There were 105 participants of whom 24 were lecturers and members of the international advisory committee. In addition to the participants from NATO countries, a small number of participants came from Australia, Hungary, Poland and Tunisia. The principal aim of the organizing committee was to bring together scientists of wide interest and expertise in the field of diffusion and to familiarize the young workers in material science with the wide range of theoretical models and methods and of experimental techniques . The Institute was concerned with the study of diffusion and related phenomena in solids which are at the cutting edge of novel technologies. The discussion of basic theories of defects in solids and their transport, with their applications in the understanding of diffusion processes in "simple solids" was followed by the wide range of current theoretical models and methods, experimental techniques and their potential. The lectures on the diffusion in specific materials included : metals, dilute and concentrated alloys, simple and compound semiconductors, stoichiometric and non-stoichiometric oxides, high-Tc compounds, carbides, nitrides, silicates, conducting polymers and thin films, ionic, superionic, amorphous and irradiated materials.

During the 2nd International Symposium on Fossil Algae, organized by the University P. & M. Curie, Paris, in April 1979, a special session was devoted to stromatolites; 29 papers were presented in French, English, or Russian. Among the papers selected originally, 16 were carried out to the final stage by their authors. They are presented here in their stratigraphical order. This selection does not pretend to cover the problem of Phanerozoic stromatolites in its entirety, but relates case histories. This should be the seed for further books analyzing and illus­ trating the paleoecology, the niche and the features of Phanerozoic stromatolites, namely throughout the Mesozoic and the Paleozoic, where the data are still scarce; this will lead to naturalistic views on the evolutionary features of Post Riphean stromes, and will sharpen tools to interpret their Precambrian ancestors. Let me introduce the papers. CLAUDE L. V. MONTY formalizes two basic types of crypt algal micro­ structures: the spongiostromate and the porostromate microstructures respectively; the rise of the latter around the Precambrian/Cambrian boundary represents a very significant step in the evolution of cyano­ bacterial microstructures and in their interaction with the environment. K. K. VERMA and G. BARMAN present a lower Phanerozoic stroma­ tolitic assemblage from Rajasthan associated with paralic alluvial fans fed by block faulting. Main stromatolite developments occurred during periods of low sedimentation and negligable tectonics, and formed in very shallow marine water. J.

Precambrian stromatolites have received in depth, consideration from geologists and paleontologists; they were indeed searching for biosedimentary structures that were sufficiently characteristic and widely distributed to be considered as useful tools for stratigraphic correlation. Silicified stromatolites are also of interest as they contain preserved traces of ancient life. Calcareous Phanerozoic stromatolites have not received very much attention from geologists. Logan's too schematic morphological classification of 1964, was not so helpful to the knowledge of Phanerozoic stromatolites because neither their morphology nor their microstructure were studied in the same detail in which Proterozoic stromatolites have now been described. We therefore know little about the Phanerozoic stromatolites which, do, however, show an interesting range of diversification. A major questions stiII remaining to be answered include the history of stromatolite development and wether their morphology has "evolved" in addition to detailed information concerning Cenozoic nonmarine stromatolites which precipitate carbonate and the Recent giant stromatolites which trap particles. For these reasons Claude Monty, in 1981, launched the first volume of what was going to be a series on "Phanerozoic stromatolites" in order to describe their morphology, microstructure and paleoecology and to present them in their stratigraphic context.

This book contains the proceedings of the NATO Advanced Study Institute on Surfaces and Interfaces of Ceramic Materials, held on the Oleron island, France, in September 1988. This Institute was organized in nine months after receiving the agreement of the NATO Scientific Affairs Division. Despite this very short time, most of the lecturers contacted have accepted our invitation to prepare a specific talk. The meeting was held at "La Vieille Perrotine" on the Oleron island. This holiday village of the French CNRS is located near the Ocean in a natural area which contributed to create a very pleasant atmosphere favourable to develop interaction between the 91 participants in this Institute. First of all, the Institute was aimed at diffusing the foremost results on the characterization of and the role played by surfaces, grain boundaries and interfaces in preparation and overall properties of ceramic materials, mainly of oxide ceramics. Through its interdisciplinary character, the Institute was also aimed at developing interaction between scientists and engineers interested in basic and practical aspects of processing and use of ceramics.