Charles S. Barrett

The University of Denver and its staff members deserve much credit for organizing and operating this Denver X-ray Conference year after year, for there seems to be no doubt that it and the yolumes that result from it are filling a need. The interests covered by the papers at one of these conferences vary from year to year and as a whole cover a wide spread of topics. This is as it should be. Old problems that have been with us for many years are being attacked again with new and more effective tools, new problems are continually arising, and new methods of great power are being developed. These developments are occurring in each of the fields covered, as may readily be seen by a glance at this twelfth volume and other recent volumes of this series. It seems clear that the policy of having these conferences and these volumes cover a wide field rather than a single one such as, for example, structure determination, or fluorescence analysis, is a policy that meets with general approval and should be continued. I understand there is every intention to do so. C. S. Barrett It is customary to acknowledge in each volume the invited session chairmen of the three-day meeting. They and the sessions at which they presided (21-23 August 1968) were as follows: CRYSTALLOGRAPHY AND DIFFRACTION. C. S. Barrett, University of Chicago, Chicago, Illinois. METHODS AND THEIR APPLICATIONS. B. C. Giessen, Massachusetts Institute of Technology, Cambridge, Massachusetts.

The 35th Annual Denver Conference on Applications of X-Ray Analysis was held August 4-8, 1986, on the campus of the University of Denver. Since the previous year's conference had emphasized x-ray diffraction, this year the Plenary Session spotlighted x-ray fluorescence, with the title "Trends in XRF: A World Perspective," featuring renowned speakers from three major areas. XRF IN NORTH AMERICA, by Prof. D. E. Leydon, from Colorado State University, dealt specifically with developments in the fields of instrumentation, data treatment and applications in that part of the world. Prof. H. Ebel, from the Technical University of Vienna, discussed XRF IN EUROPE, concentrating on subjects including total reflection, improved fundamental parameters, quantitation without standards and imaging techniques. Tomoya Arai, of the Rigaku Industrial Corporation in Japan, in considering XRF IN THE FAR EAST, described the scientific activity in XRF and the applications thereof, primarily in Japan and China. These plenary lectures were interspersed with short discussions of PERSONAL OBSERVATIONS on the subject by the co-chairmen of the SeSSion, Ron Jenkins and myself. The intent of this session was to bring the audience up-to-date on the status of the field in various parts of the world, and to give some feeling concerning where it is likely to go in the immediate future. Hopefully, the publication of the written versions of those presentations in this volume will make the authors' thoughts available to many who could not be present at the conference.

The continuing success of the Denver X-Ray Conference is, it seems to me, the consequence of three equally important facets of each meeting. These are: 1) the collegial atmosphere and workshops at which experts and novices mix, talk, and informally share information at many levels; 2) the plenary session at which information is presented that intentionally brings new ideas to attendees to broaden the scope of the field; and 3) the traditional sessions in which interesting reports on current research and applications are presented in a timely and professional way. The first and last of these are discussed separately by Paul Predecki and are organized (no small task!) by the entire advisory board. This requires much more than deciding whether yet another workshop on specimen preparation is needed and whom to prevail upon to organize and present it. In fact, few attendees at these workshops ever appreciate the level of effort that Paul and his staff expend to make sure everything comes off smoothly, even when hundreds of copies of handouts need to be whipped off at the last moment, travel problems arise, or unusual audio­ visual aids are suddenly needed. But my topic here is the second of the three facets listed above - the plenary session. Organizing this falls to a single individual, on the theory that one person can then approach enough others as speakers to put together a unified and yet diverse program of related and interesting review papers.