AMERICAN CRYSTALLOGRAPHIC ASSOCIATION

FALL NEWSLETTER

Table of Contents
President's Column
ACA Council News
ACA Standing Committee
CISTI News
USNCCr/ICDD Travel Awards for Glasgow
Hanawalt Award
Patterson Award
New Program for Structure Determination
Ken Trueblood
Jack Moriarty
ACA Meeting Reports
ACA Corporate Members
Northwest Crystallography Workshop
Meeting and Course Announcements
Contributors to This Issue
Polycrystal Book Service
Calendar of Meetings
Employment Information

Contributions to the ACA Newsletter should be sent to either Co-Editor:

Ron Stenkamp Dept. of Biol. Structure Box 357420 U. of Washington Seattle, WA 98195-7420 tel. 206-685-1721 fax 206-543-1524 stenkamp@u.washington.edu

Judith L. Flippen-Anderson Code 6030 Naval Research Labatory Washington, DC 20375 tel. 202-767-3463 fax 202-767-6874 flippen@harker.nrl.navy.mil

Articles by e-mail or on diskettes are especially welcome. Deadlines for newsletter contributions are: February 1 (Spring issue), May 1 (Summer), August 1 (Fall), and November 1 (Winter). Matters pertaining to advertisements, membership inquiries, or use of the ACA mailing list should be addressed to:
Marcia J. Colquhoun, Administrative Manager
American Crystallographic Association
c/o Hauptman Woodward Medical Research Institute
73 High Street
Buffalo, NY 14203-0096
tel. 716-856-9600, ext. 321; fax 716-852-4846
E-mail: marcia@hwi.buffalo.edu

ACA Home Page http://www.hwi.buffalo.edu/ACA/

ACA Newsletter (ISSN 1058-9945) Number 3, 1998. Published four times per year in the spring, summer, fall and winter for the membership of the American Crystallographic Association, P.O. Box 96, Ellicott Station, Buffalo, NY 14205-0096. Membership in the ACA includes a non-deductible charge of $1.75 from membership dues to be applied to a subscription to the ACA Newsletter. PERIODICALS POSTAGE PAID AT BUFFALO, NY. POSTMASTER: Send address changes to ACA, c/o 73 High St., Buffalo, NY, 14203.

President's Column
It is difficult to find a topic for this column so shortly after the annual meeting. The excellent talks, posters, exhibits and one-on-one conversations for the week in Washington, D.C. stimulated those who attended the meeting and reminded us of the excitement of our discipline. The organizers - both local and program - did an outstanding job; even the weather co-operated as it was too hot to be tempted away from the meeting by the many attractions of the capital! My personal congratulations and thanks to everyone involved in the 1998 meeting.

An issue that is common to all of our lives is the degree and rate of change - change in our daily activities, in our discipline, in our workplace and in the Association. As Jon Clardy noted in his banquet speech, the ACA will be faced with the need to adapt to new circumstances in the coming years. Those of you who have been members for a long time know that the ACA and its annual meeting have changed a great deal. We have become larger, more demanding of our conference facilities, better supported with high quality staff, more sophisticated in our use of publication technology, more conscious of our role in public and scientific policy, and attractive to a larger range of scientific interests. I think we meet comedian Will Rogers' standard of "on the right track"; however, as Will said, "Even if you are on the right track, you'll get run over if you just sit there."

Crystallographers have distinguished themselves by their quick adoption of new technologies. Think of the advances in computation technology (punched cards and paper tape to personal workstations), display (Richards box to graphics workstations), data collection (manual 3-circle diffractometers to CCDs) in just the past 30 years. Interestingly, we are not as quick to welcome change in the organizations that surround us, either our workplaces or the Association. Certainly balance between the habits of old and new practices must be found; we are wise to heed the advice of Lady Astor, who said, "The main dangers in this life are the people who want to change everything or nothing."

As the organization grows and the technologies and practices of our discipline change, it will be important for Council to adapt our organization's structure and the content of the annual meeting to be inclusive of all of the interests of the membership. I hope you will join in a conversation with Council to find the opportunities to provide better service and an even more dynamic annual meeting for the members. I also hope that you will be willing to look at old habits and ask if they are appropriate for the kind of organization we need in the next 30 years. You will find reports from the Standing Committees in this newsletter; they are intended to begin a conversation regarding appropriate committee structures and mandates for the future. For, as Anne Morrow Lindbergh said, the one thing we can be sure of is "the wave of the future is coming and there is no stopping it".
Penny Codding

Council News
The ACA Council met on Friday, July 21, at the Crystal City Hyatt. Jane Griffin and S. N. Rao reported that the ACA is in good financial condition. The ACA administers $276,585 in various award funds. In addition, the ACA has assets of $432,852 which are invested in Treasury Bills, certificates of deposit, and Vanguard indexed mutual fund. With assets of this magnitude it was decided that the Financial Advisor should be an ex officio member of the ACA Council.

The former Monograph Fund and the Wood Fund will be merged and called the Wood Fund. It was decided to increase the amount and/or number of Etter Student Travel Awards since the fund jas grown to $66,000. A standard practice is to spend 50% of the earnings from the principal each year. It was also decided to establish Etter Lectures at ACA meetings, to be given by speakers at the beginning of their careers (before tenure). Travel support for these lectures will come from the Etter fund.

The Canadian Representative, George Ferguson, has resigned. He will be replaced at the fall election.

The purpose and function of the ACA committees was discussed by Council with the committee representatives in a lunch time meeting. There was further discussion by the membership at the ACA Business Meeting. Council received written reports from all the standing committees. The Continuing Education Committee plans the ACA workshops and evaluates applications for student travel funding; these functions will continue to be necessary. Some of the original functions of the Apparatus & Standards Committee and the Data & Computing Committee are changing as there are advances in crystallographic methods. We discussed the possibility of forming a consolidated committee-Crystallographic Hardware and Software-since there are overlaps between these two committees. Likewise, the Publications Committee may shift its focus from print to electronic media. Council will discuss committee structure at the October meeting.

Ethan Merritt enumerated some concerns of the Apparatus & Standards Committee: 1) standards for the publication of small molecule structures; 2) referees need to have coordinates of protein structures when they review the manuscript; 3) some referees don't have the crystallographic expertise to review crystallographic articles; 4) former academic software is being converted to commercial "black boxes" with no source code available. Codding asked the Committees for a report at the October meeting on this problem with software.

ACA Council intends to affiliate with the American Association for the Advancement of Science. This is in addition to our affiliation with the American Institute of Physics. There are no monetary costs associated with the affiliation; Council considers it a way to raise our profile and to publicize crystallography.

Council met with the program and local chairs for 1998, 1999 and 2000 to facilitate an exchange of ideas and experience. The 1999 meeting in Buffalo will be jointly sponsored by the ACA and the American Association of Crystal Growth. The Program Chair Steve Ealick announced that the Transactions Symposium will be titled "Two Decades of Synchrotron Research." Both biological and non-biological applications of synchrotron radiation will be presented. Two workshops are planned.

Council met with representatives of the SIGs in a series of morning and lunch time meetings. Many interesting ideas for sessions and workshops at the 1999 Buffalo meeting were presented to Council and the 1999 Program Chair, Steve Ealick.

David Cox reported that the Materials Science SIG would like to explore holding joint meetings with the Denver Diffraction Conference. Perhaps the ACA could co-sponsor some sessions at the DDC. Or an entirely new meeting might be held under the joint auspices of the DDC and the ACA. For several years Council has been making overtures to the DDC, suggesting a joint meeting. The problem has been finding a site large enough for the two groups.

Victor Young (Service Crystallography) and Richard Harlow (Small Molecules) announced that the two SIGs may unite to form a new SIG called Chemical Crystallography SIG. A letter will be sent to members of both SIGs giving the reasons for the proposed change.
Virginia B. Pett

Committee Reports
The four standing committees prepared reports explaining their mandates and activities to provide a base for discussion about reorganizing them. Following are the reports.

Apparatus & Standards Committee Report Annual Report
Committee Function
Several of the specific charges to the committee are now effectively obsolete, as listed below, but in general the role of the committee is still relevant. Specific charges to the committee that might be changed or updated include:
evaluation of X-ray film (no longer relevant)
maintain a listing of owners of X-ray instrumentation (not practical for the committee, and in general the information is readily obtained from equipment vendors)
to keep ACA members informed through the Newsletter... (the Newsletter is great, but it is probably more to the point that current information and data be available electronically, via the world wide web and ftp archives)
The distinction between "Apparatus" and "Crystal Data & Computing" has become very blurred. There is a correspondingly increased area of overlap in the interests of the two respective ACA committees. We do not view this a problem, but do recognize it as an issue the Council may wish to consider.

Education
The committee should play a role in organizing and promoting education of the ACA membership on new technologies, apparatus, and techniques. This function will clearly overlap with the interests of other ACA committees and SIGs, but we do not think that this is in any way a problem.

In 1998 the A&S Committee sponsored a session at the Washington ACA meeting on current CCD Area Detector technology.

In 1999 the Committee intends to sponsor a workshop on "Non-routine techniques" to be held under the auspices of Alan Pinkerton.

The committee has also discussed creation of a web site on which to publish proceedings of these or other workshops, as well as other materials relating to established standards. Given the existence of IUCr and other crystallographic resources on the web, it is not clear to us at this point whether there is in fact a need for a new site or whether the committee should simply facilitate the publication of HTML versions of documents via existing sites. Pointers to the relevant web sites will be published in the ACA Newsletter.

Publication Standards
The committee has discussed two issues relating to peer-review and publication of crystal structure determinations. In each case we propose to encourage discussion within the ACA membership and the larger crystallographic community in an attempt to identify a consensus that can be communicated to the editorial board of relevant journals. We view these issues as similar to previous discussions on required deposition of protein coordinates with the PDB. In brief, the two proposed policies are:
1) There should exist a set of minimum standards for data collection (e.g., resolution range, counting statistics) for publication of small-molecule crystal structures.

2) Coordinate files for protein structures should be made available to referees upon request, subject to a signed confidentiality and non-disclosure statement if necessary, so that the validity of the structure may be judged at the time of review.

The two statements above should be taken only as my (EAM) synopsis of the issues rather than a formally worded policy statement. The committeemet in Washington to discuss these issues further.

Community input on all the above topics may be solicited via letters to the editor, via discussion on sci.techniques.xtallography, and via semi-formal sessions at future crystallographic meetings.

Equipment Standards
The committee has discussed the desirability of proposing and facilitating the distribution of standard crystals for calibrating both small-molecule and protein diffraction setups. In particular we feel that it would be useful to identify a protein crystal form that is robust, easily replicated, has at least one "long" cell axis, contains a metal atom with an anomalous signal as measured at Cu Ka, and is amenable to liquid-nitrogen temperature storage.

Data Interchange Standards
The committee is potentially interested in the establishment of standard formats for data storage and exchange. However, this area seems to be currently under the purview of other bodies such as the Crystal Data & Computing Committee and the mmCIF and ImgCIF working groups.
Ethan A Merritt, Chair. Other members of the committee are Bernie Santarsiero and Alan A. Pinkerton.

Continuing Education Committee Report Annual Report
Mandate #1: Organizes a one-day workshop to precede the annual meeting.
The 1997 Continuing Education Committee consisting of Cynthia Stauffacher (Chair), Douglas M. Ho and Jeanette Krause-Bauer elected to organize a joint small molecule / macromolecule workshop. The topic and title of the workshop were "Riding the Fence Between Large and Small Molecules: Current Approaches to the Solution and Refinement of Atomic and Near-Atomic Resolution Data". The workshop was held on Saturday, 18 July 1998, at the SGI training facilities in Silver Spring, Maryland. Cynthia served as the program chair, and the invited lecturers were George M. Sheldrick (Shelx 97), R.A.G. de Graaff (Crunch), Russ Miller (Shake-n-Bake), A.L. Spek (Platon/Squeeze), Axel Brunger (CNS), Charles W. Carter (Bayesian), and Lynn F. Ten Eyck (Eigensystem Analysis). In addition to lectures, the workshop endeavored to provide the participants with hands-on exposure to software and programs that they might not have had an opportunity to try on their own before. Twenty-four SGI workstations were available, and in general, all of the software functioned properly, and people were pleased with the individual attention that they received from the speakers. Jeff Dechamps (NRL) served as our liaison to SGI and did a superb job of coordinating the setup and operation of the workstations, and the coffee breaks and terrific lunch as well. The task of getting the workshop notes bound on time fell to Marcia Colquhoun (ACA). Jeff and Marcia were absolutely indispensable and untiring, and we cannot thank them enough for their efforts and guidance without which the workshop would surely have not happened.

Mandate #2: Develops and maintains a list of potential workshop topics.
A list of "potential" topics cannot be maintained without knowing what came before. Hence, a list of past workshops is of direct value in any attempt to plan for the future. Past workshops included: Anomalous Dispersion Techniques and Calculation, Cambridge Structural Database Version III, Role of Numeric Databases in Materials and Biological Sciences, Rietveld Analysis, Molecular Dynamics, Accurate Single Crystal Diffractometry, Crystallization and Crystal Growth of Proteins and Related Compounds, Communicating Crystallographic Results: Will They Believe You? And Will They Fund You?, Biomolecular Interactions: A Practical Workshop on Computational Approaches, Isomorphous Replacement Methods in Macromolecular Crystallography, Opportunities for Crystallography at National Synchrotron and Neutron User Facilities, Cambridge Structural Database, Science with a Scientist, The Crystallographic Information File (CIF), SHELXL - Refinement of Small Molecules and Macromolecules with High Resolution X-ray Data, Small-Angle Scattering Studies: Microstructure on the Nanometer Scale, Measuring Electron Density Distributions, A Decade of Structure-Based Drug Design: What Have We Learned, Where are We, and Where are We Going?, Research Opportunities at Third Generation Synchrotron Sources, Modeling Disordered Materials, Riding the Fence between Large and Small Molecules: Current Approaches to the Solution and Refinement of Atomic and Near-Atomic Resolution Data, and Data Handling for Small Angle Scattering.

Tentative plans for a 1999 ACA Workshop in Buffalo titled "Se-Met Biotechnology / Xenon Derivatives and Related Techniques" were forwarded by Steve Ealick to the Continuing Education Committee. The workshop would encompass such topics as preparing SeMet proteins for MAD phasing, xenon and krypton cryocrystallography, purification of membrane proteins, crystallization of macromolecular assemblies, etc. A second workshop on the theoretical underpinnings of area detector technologies, and on the collection methodologies and techniques believed to maximize the benefits of having and using such technology is also being planned. Our second-year member (Jeanette Krause-Bauer) will be charged with organizing the Buffalo workshops per our mandate.

Mandate #3: Develops guidelines on the planning and execution of workshops.
The Continuing Education Committee has drafted a template for generating a written "Guideline for Workshops" to assist future committee members in the organizational, planning and execution phases of these endeavors. This "Guideline for Workshops" will be authored by our newest member (Raymond Davis), and will include such things as Suggestions on How and When to Choose a Topic and Title, Suggestions on Setting a Goal and Intent for the workshop, Suggestions on Selecting a Format for the workshop that best supports achieving that goal and intent, Suggestions on Finances, Suggestions on Internal Tasks to be covered by the committee members, Suggestions on External Tasks to be covered by the Local Organizers, Suggestions on How and When to recruit a Program Chair, Suggestions on How and When to Invite Lecturers, Suggestions on Addressing the Special Needs of some lecturers, Suggestions on How and When to get Written Notes from the lecturers, and Suggestions on Follow-up Reporting and Paperwork to the ACA Newsletter. Additional topics and sections for inclusion are welcomed.

Mandate #4: Evaluates and ranks the student travel grant applications.
There were 68 student travel grant applications (requesting a total of $65,427) that were reviewed and ranked by the Continuing Education Committee in 1998. Only $15,000 in funds were available for distribution, so clearly only a fraction of the requests could be supported. There were many fine applicants, e.g., William R. Wikoff (Scripps), Stephen T. Miller (Harvard), Louisa Smith (Leeds), Haihua Luo (Missouri-Columbia), J. Anand Subramony (U. of Washington), Tianyan Niu (Houston), Christopher L. Cahill (Stony Brook), Jennifer A. Swift (Minnesota), and Damon A. Parrish (Toledo). Congratulations to all. For comparison, in 1997, the corresponding numbers were 62 applications totaling $55,453, and only $10,000 in funds were available.

Mandate #5: Evaluates and identifies the "top ranked abstract" by a student.
The Continuing Education Committee was charged with identifying the top ranked abstract submitted to the 1998 meeting in Arlington. We are pleased to have recommended Benjamin Perman's "Signal Transduction on the Nanosecond Time Scale: Early Structural Events in the Photocycle of a Xanthopsin". It goes without saying though that there were many other fine abstracts.Congratulations are to be extended to all for their efforts.

Mandate #6: Submits a summary report on the workshop.
Cynthia Stauffacher served as the program chair for the workshop and has agreed to provide us with a summary.

Mandate #7: Surveys and evaluates the status of training and education.
No action taken at this time. It is recommended that a questionnaire be drafted and distributed to the membership in the Spring of 1999; the responses and data acquired to be presented at either the 1999 or 2000 ACA Meeting as a "Summation of Crystallographic Training and Education in the 20th Century".

Mandate #8: Recommends candidates for membership to the Nominating Committee.
An effort should be made to encourage and nominate macromolecular colleagues to run for a seat on the Continuing Education Committee during the next election. To complement Jeanette Krause-Bauer's strength in small molecule crystallography, and Ray Davis' in materials and methods, the community would be best served by nominating and electing an individual with biological or macromolecular interests for balance. Two potential candidates were recommended (names not disclosed here to protect the "innocent").
Douglas M. Ho, Chair, Jeanette Krause-Bauer, Raymond E. Davis

Publications Committee Report Annual Report
The letter from Dr. Codding asking for a review of the operations of the Publication Committee requested we address four questions:

(1) Is the committee still needed?

(2) Do the terms of reference need revision?

(3) If the committee is to be retained, how can its work be brought to the attention and benefit of the ACA members?

(4) Are there other areas of interest to members that need attention of a standing committee?

Need
The brief response to these is that there will be from time to time matters of special interest to crystallographers which will need publishing but which will not attract any major publisher. From what I know of the Donald L. Ward Patterson Peaks publication, the negotiations between the author, Polycrystal Book Service and the ACA have taken two+ years to bring it to the publication stage and a permanent committee is needed to administer the funds and see the job to completion.

In the context of easy desk-top publishing for such things as class notes and the electronic medium, there is the question as to whether there is a need for hard-copy publications. For me, the interesting thing to watch of even my most Internet-literate students and young colleagues is how they always, when faced with a really testing problem, settle down with a text (and copies of papers) and ponder over it reading and re-reading. There remains then a place for properly produced hard-copy texts.

The ACA needs thus to have a small group permanently on watch for such enterprises and other such publication opportunities.

Terms of Reference
The Ward publication is also on the Internet - the publications committee mandate should be extended at least to publications available via electronic methods. The Ward publication also relied heavily on the expertise from Polycrystal Book Service. It would seem to make sense if someone, closely connected to Polycrystal, were assigned to the committee in some advisory capacity (see also 3 below)

Publicity
A simple expedient would be to place a link on the ACA web page to a publications committee page where information about the mandate, the officers and the opportunities could be given. A connection to Polycrystal would also bring in a different sort of inquiry and expertise.

Other Areas of Interest
With reference back to question 2, there should be somewhere an archive of the ACA where all the lore, fables, anecdotes and history of the founding crystallographic fathers is held. Many of these are elderly, some have died, and it would be a pity to lose all their wit and wisdom. (As time goes on the archive would, of course, have to be expanded to include the next generation ....). For example, in answer to the question "Who was Ted Maslen?", the first reply should be to bring out Hall's great eulogy. I have a copy, there is still a copy on the IUCr Web, but will it still be easily available in five years to members of the ACA?

Such an archive is easy to outline, it is very much harder to collect since you have to consider the terms of reference of the collection. Should this be only "as reported by the founding father" - the authorised biography (sometimes hagiography). Or should it be "as reported by sources not always identified" - the unauthorised biography (sometimes the hatchet-job)?

Anyway, someone somewhere should be keeper of this lore.

A second need is a guide to the crystallographic educational software. One member of our committee makes the point that there are many crystallographically inexperienced research workers now using crystallographic methods and they need a guide to the educational software to find what might be of help to them. Here the responsibilities of the Continuing Education Committee and the Publications Committee obviously overlap.
Stan Cameron, Chair. Other members of the committee are Ron Stenkamp and Douglas C Rees.

Crystallographic Data and Computing Committee Report Annual Report
There are no major developments to report regarding the activity of the committee, at least so far in 1998. Thus, as in recent years, the committee has not been very active, although some issues have been considered by individual committee members. To some extent this reflects the fact that broadly speaking matters of crystallographic data and computing are in good shape rather than in crisis. A contributing factor is certainly the good exchange of information and even software via the WWW.

Some developments and issues of concern with potential need for committee input are the following:
CIF
Following the widespread adoption and the success of the CIF in the small molecule community, CIF is coming to the macromolecular community. What are the likely concerns and potential problems? Will it be so readily embraced?

Crystallographic Databases
The CSD and PDB are generally working well, and serve the crystallographic community well. There is, however, still some unhappiness in the protein crystallography community about the efficiency of the PDB in the past in spite of the dramatic improvements in the last 2 years. Consequently, each time PDB needs a grant renewal there is competition for the contract, with the potential of putting the current PDB operators out of business. This might be disastrous for continuity.

The committee could survey the crystallographic community regarding positive and negative aspects of all the crystallographic databases, with a view to providing some feedback to the databases operators.

Christophe Verlinde has been promised by the PDB a list of structures for which structure factors have not been deposited, so that he can encourage people to fix that problem. However, the list has not yet been made available.

Crystallographic Software
There is more crystallography software than ever before, most of it available freely (or for a nominal fee). There is, however, a disconcerting trend in the availability of data processing software. More and more authors make deals with data acquisition instrument companies to commercialize their software; also, they do not provide source code anymore (e.g., the DENZO program). This results increasingly in 'black box' data processing, which could be a real problem.

Future mandate of the Committee
Specifically:
1. Do we need a committee still devoted to this mandate?

2. If yes, do the terms of reference need revision? Please suggest new terms of reference?

3. If the committee is to be retained, how can its work be brought to the attention of and directly benefit the ACA members?

4. Are there any other areas of interest to members that need the attention of a standing committee? Data and Computing cannot fail to be of central importance to crystallographers, which argues in itself for the continued role of this committee. In particular the Committee can (and should) play a role in:

(i) Helping to resolve or provide information on issues within its mandate (i.e. data and computing). In this role the committee would respond to a problem identified by the crystallographic community and serve as a focal point for discussion and possibly resolution of the problem.

(ii) Helping to guide policy/trends in situations where lack of standards or lack of uniform approaches to issues of data or computing are seen to be a problem to crystallographers (e.g., data format standards, computer platforms for widely used software).

These roles would benefit from some means of direct communication between the Committee and the ACA membership. The simplest means might be via a web page, but someone would have to maintain this. The level of committee activity in recent years (I can speak for 2.5 years - Lee) has been quite low. This may reflect the need (or lack of need) for this committee, the lack of really "burning issues" in the past couple of years, or may simply be a variable function of committee membership. The points raised above argue for the continued operation of this committee particularly one that has the facilities to stay in touch with the broader crystallographic community more readily. However, a continued low level of activity may argue for combining the function of this committee with one of the other standing committees, e.g., Apparatus and Standards.
Lee Brammer, Chair. Other members of the committee are Christophe Verlinde and Robert Von Dreele.

New Director General of CISTI Appointed
Jacques Lyrette, Vice-President, Technology and Industry Support, National Research Council of Canada (NRC) announces the appointment of Bernard Dumouchel as Director General, Canada Institute for Scientific and Technical Information (CISTI).

Mr. Dumouchel has over 28 years of experience in library services. He joined NRC in 1987, first as Director, Resource Development where he was responsible for Acquisitions, Cataloguing, and CISTI's branch libraries across Canada. In 1993, he assumed responsibility for Document Delivery Services and Electronic Information Services and became Director, Operations. In this capacity Mr. Dumouchel successfully led his program through significant changes.

In making the appointment, Mr. Lyrette said, "The next few years will be highly challenging for CISTI as it reaches the next millenium. The role and mandate of CISTI is evolving and will continue to evolve in an ever-complex world of scientific and technical information."

In 1969, Mr. Dumouchel received a B.A. from the University of Ottawa, a B.L.S. in 1970 from the University of Ottawa and an M.L.S. from the University of Western Ontario in 1980.

New Developments in the Global Information Industry: CISTI Enters into Partnership with the Far East
The Canada Institute for Scientific and Technical Information (CISTI) of the National Research Council Canada and the Science and Technology Information Center (STIC) in Taipei, China, have entered into an agreement that will enhance access to scientific, technical and medical information within their respective economies by sharing resources, technologies and expertise. CISTI and STIC also plan to exchange staff for training purposes.

With this agreement, CISTI will tap into a large Chinese-language collection of scientific and technical information published in Chinese Taipei, Mainland China and throughout the South East region. Canada will therefore have access to approximately 1200 Chinese -language scientific and technical journals. In the past decade, Taiwan has increased the quantity and quality of its high-technology research with new facilities and the allocation of considerable funds. This makes the information a valuable resource for Canadians.

CISTI's clients have growing expectations and their information needs are changing and increasing at a rapid pace. This strategic alliance meets our goal of remaining at the forefront of scientific, technical and medical information by enhancing our virtual collection and by providing value-added and highly competitive services.

CISTI, part of the National Research Council of Canada, is North America's largest science and technical library and Canada's leading publisher of scientific journals.

For more information, please contact:
Elizabeth Katz, Head, Communications
Canada Inst.e for Scientific & Technical Information (CISTI)
1-800-668-1222 or (613) 993-3854
E-mail at elizabeth.katz@nrc.ca
CISTI's web site is www.nrc.ca/cisti

USNCCr / ICDD Travel Awards to Glasgow
The 18 th Congress and General Assembly of the International Union of Crystallography (IUCr) will take place in Glasgow, Scotland in August 1999. The US National Committee for Crystallography (USNCCr) and the International Centre for Diffraction Data (ICDD) will have limited funds available to subsidize students and young scientists (within 3 years of graduation) residing in the United States. Preference will be given to those presenting a paper. Application forms for the travel awards can be found at the ACA web site or at either the USNCCr web site (http://www.sdsc.com/XTAL/USNCCr/USNCCr.html) or the ICDD web site (http://www.icdd.com). Applications may also be obtained from the chair of the Awards Committee:

Jane Griffin
Hauptman Woodward Research Institute
73 High Street
Buffalo, NY 14203-0906
Deadline for receipt of applications is February 15, 1999.

Herbert Göbel to Receive the J.D. Hanawalt Award
The International Centre for Diffraction Data takes pleasure in announcing that Dr. Herbert Göbel, Siemens AG, ZT MF 7, Otto Hahn Ring 6, München, Germany, was selected to receive the J.D. Hanawalt Award for excellence in the field of X-ray Powder Diffraction. The J.D. Hanawalt Award is presented every three years for important, recent contributions to the field of X-ray powder diffraction. The award consists of a citation and a cash gift of $1,000. Dr. Göbel presented an abstract and a paper on the work being recognized at the 47th Annual Denver X-ray Conference in Colorado Springs, CO. The presentation of the award also took place at the same conference.

Development of a New Program For Structure Determination: Crystallography & NMR System
Two years ago, development was started on a new program for structure determination called Crystallography & NMR System. This program is the result of an international collaborative effort among several research groups. The program has been designed to provide a flexible multi-level hierarchical approach for the most commonly used algorithms in macromolecular structure determination. Highlights include heavy atom searching, experimental phasing (including MAD and MIR), density modification, crystallographic refinement with maximum likelihood targets, and NMR structure calculation using NOEs, J-coupling, chemical shift, and dipolar coupling data. A paper describing the philosophy of the program will soon be published in Acta Crystallographica D.

Crystallography & NMR System will be made available to both academic and commercial users. The program will be provided to academic users with a small adminstrative fee and to commercial users through a yearly licensing scheme which will support a non-profit support and development group. This non-profit support and development group, headed by Dr. Paul Adams, has already been initiated at Yale University. Other members of the group currently include Dr. Ralf Grosse-Kunstleve. It is expected that other positions will be added later.

As a consequence of this development, Dr. Brunger's group has terminated all development and support of the program X-PLOR. There is no active relationship between Dr. Brunger's group and Molecular Simulations Incorporated and no future relationship is planned.

Announcement of the official release of Crystallography & NMR System will be made on the Internet as soon as it is available.

Axel T. Brunger, Professor of Molecular Biophysics and Biochemistry, Investigator, Howard Hughes Medical Institute

Principal Members of the Collaborative CNS effort:
Dr. Marius Clore, National Institutes of Health
Dr. Piet Gros, Utrecht University
Dr. Michael Nilges, EMBL Heidelberg
Dr. Randy Read, Cambridge University

Gérard BricogneWins Patterson Award
The Patterson Award is awarded to Gérard Bricogne for his fundamental analysis of structure factor statistics and implementation of optimal computational algorithms to update, sample, and evaluate accurate joint probability distributions of structure factors at any resolution given strong, phased reflections and to combine all sources of phase information with that shown by Patterson to lie within the amplitudes themselves.

These accomplishments were summarized by a nominator as follows: "In 1984 he wrote the first of three fundamental papers on the macromolecular phase problem as a whole: "Maximum Entropy and the Foundations of Direct Methods" (Acta Cryst. (1984), A40, 410-445). This was followed by "A Bayesian Statistical Theory of the Phase Problem. I. A Multichannel Maximum-Entropy Formalism for Constructing Generalized Joint Probability Distributions of Structure Factors" (Acta Cryst. (1988), A44, 517-545), and by "Direct Phase Determination by Entropy Maximization and Likelihood Ranking" (Acta Cryst. (1993), D49, 37-60). The first provided a technique for computing, without approximation and throughout the course of the structure determination, accurate and fully updated joint probabilities of the structure factors. The second broadened the treatment to include all currently used sources of phase information, and the third contained important ideas for a future multisolution computer program, including new methods based on error-correcting codes and likelihood ranking for reducing the spreading of the search tree. The entire series is characterized by an extraordinary level of mathematical beauty."

The breathtaking beauty of Bricogne's work is matched by its practical power for structure determination. His contributions to crystallography are closely aligned with and extend Patterson's own insights about the exploitation of measured intensities in pursuit of accurate structural conclusions. Few areas of crystallography will remain untouched by them. The most decisive accomplishment has been to transform statistical direct methods into a coherent program for improving phase determination in the absence of atomic resolution X-ray data. The methods also have enhanced electron diffraction and can potentially be applied to neutron diffraction. Generalizing the mathematical framework to powder diffraction, he introduced the concept of "hyperphases" to represent the combined loss of ordinary phases and reflection overlap. Proper treatment of structure factor statistics resulted in fundamental improvements for applications previously considered to be well-established and perhaps even optimal, including maximum likelihood parameter refinement for isomorphous displacements, partial structural models, maximum-likelihood Rietveld refinement, and accurate charge-density calculations. Each application illuminated in new ways the continuing challenge of the crystallographic phase problem, pointing toward better solutions.

Gérard Bricogne was born in 1949 in Aix en Provence, France. He studied for the Ph.D. degree with David Blow at the MRC Laboratory of Molecular Biology in Cambridge, England, where he developed the use of noncrystallographic symmetry for protein and virus structure determination. This work was immediately successful; he implemented real-space averaging in new computer programs and used them in the solution of the first two virus structure determinations at atomic resolution (TMV and TBSV) with Aaron Klug and Stephen Harrison. While at Cambridge, he had the rare distinction as a French national to be appointed a Research Fellow of Trinity College. His first independent position was at the College of Physicians and Surgeons, Columbia University, New York, where he worked from 1981-1983. He then returned to Orsay, France to assume the position of Directeur de Recherche at L.U.R.E., where he retains an appointment. He worked from 1992-1993 as Tage Erlander Visiting Professor at Uppsala University, Sweden. From 1993 he has worked at the MRC in Cambridge, where he holds a Howard Hughes International Research Scholarship. He is the recipient of numerous awards, notably the Prix Grammaticakis-Neumann of the French Academy of Sciences and the Dorothy Hodgkin Prize of the British Crystallographic Association.

After establishing the equivalence between real-space averaging and the reciprocal space formulations of Rossmann, Blow, and Crowther, Bricogne recognized that more powerful assaults on the macromolecular phase problem required an appropriate way to combine prior knowledge such as noncrystallographic redundancy with the structure factor statistics underlying direct methods. In a masterstroke of mathematical reasoning, he showed that the saddlepoint approximation to the joint probability distribution of structure factors was essentially equivalent, and slightly superior to, the real-space maximization of a constrained entropy function. This proof, recognized by the Prix Grammaticakis-Neumann, initiated an extended reformulation of the entire edifice of direct methods into what he refers to as the "Bayesian paradigm", involving the following innovations:

1. The saddlepoint method provides an effective numerical procedure for complete and accurate construction of joint probability distributions of structure factors for the random atom model used in Direct Methods and of conditional distributions when phases are known for any number of strong reflections (Bricogne, Acta Cryst., 1984, A40, 410-445).

2. The log-likelihood gain provides an optimal figure of merit for "hypotheses" about phases and other unknown quantities.

3. An important, but nontrivial generalization of Bertaut's structure factor algebra was necessary to facilitate the evaluations of trigonometric moments used in many computations, notably the variance-covariance matrices required for the analytical solution of the saddlepoint (Bricogne, Acta Cryst., 1988, A44, 517-545).

4. Multichannel maximum entropy constructions provided for the incorporation of all potential sources of phase information under a single, optimal computation scheme (Bricogne, Acta Cryst., 1988, A44, 517-545).

5. Error-correcting codes as factorial designs for the permutation of unknown phases enhanced the sampling efficiency of "magic integer" permutation schemes by orders of magnitude, bringing meaningful permutation strategies into range for large macromolecular structures (Bricogne, Acta Crystallographica 1993, D49, 37-60).

6. Multidimensional Fourier Transform techniques to analyze "coupling" between reflections by probabilistic relations strengthened the approximations known as "convergence mapping". The invertibility of these relationships meant that they can be used either to analyze a set of LLG scores from a phase permutation experiment or to project the likely outcomes of potential permutation experiments (Bricogne, Acta Crystallographica 1993, D49, 37-60).

7. Incorporation of prior stereochemical knowledge into structure factor statistics, again extending the fundamentals of direct methods by generalizing the statistics of the random atom model to include random distributions of positions and orientations of known chemical fragments. Bricogne expects the resulting joint distributions of structure factors to open the way to ab initio phasing at typical macromolecular resolutions and to a tight interface between computational protein crystallography and genomics.

Bricogne's work is firmly grounded in his mastery of the mathematical phenomena underlying structure determination. His compelling chapter on Fourier transforms in Volume B of the International Tables points toward unexpected new uses of Fourier transform theory to facilitate many otherwise difficult calculations, notably multidimensional FFT analysis of phase permutations on error-correcting code designs. Although he usually writes with the concision of a mathematician, excellent practical summaries (Bricogne, Methods in Enzymology, 1997, 276, 361-423; La Fortelle and Bricogne, Methods in Enzymology, 1997, 276, 472-494; Bricogne, Methods in Enzymology 1997, 276, 424-448; Bricogne, Methods in Enzymology, 277, 14-19) provide lucid presentations of most of his methods.

Members of the Patterson Award Selection Committee: Lee Brammer (University of Missouri-St. Louis), Chair, Helen Berman (Rutgers University), Charles Carter (University of North Carolina), Judith Kelly (University of Connecticut).

Kenneth Nyitray Trueblood
Kenneth N. Trueblood, President of the ACA in 1961, died on 7 May 1998 at his home in Los Angeles of cancer (melanoma). He was 78 years old.

Ken will be remembered for his pioneering work in developing computer programs so that crystallographers could calculate electron-density maps in three dimensions and refine the structures they found. The early computer at UCLA (SWAC, National Bureau of Standards Western Automatic Computer) was, in the 1950s, one of the most advanced anywhere. Ken used its computational power to help countless crystallographers of the time.

He is also known for his studies of crystal structures including hydroxy-L-proline, some nucleic acid bases (with Jerry Donohue), several strained polycyclic hydrocarbons and metal-ion complexing agents (with Donald Cram and Emily Maverick), and particularly, vitamin B12 and its hexacarboxylic acid derivative (with Dorothy Hodgkin). Ken made significant contributions to the discovery of the chemical formula of this vitamin by his use of the computer programs written for SWAC.

Ken was an expert in molecular motion, and did many analyses with Verner Schomaker and Jack Dunitz on rigid-body vibrations and rotation barriers in crystals. When he heard the dismal prognosis of his final illness, he put the completion of an article with Verner Schomaker (who died last year) at the top of his "to-do" list. This study of the correlation of internal torsional motion with overall motion in crystals was finished in good order and is now in press in Acta Crystallographica B.

Ken is also remembered as a superb teacher. This aspect of his talents was highlighted by former students at the session organized by his one-time graduate student, Bob Sparks, in his memory at the ACA meeting in Arlington, July 1998. They described how he expected students to be precise and innovative in their studies, but also how hard he worked to ensure they understood the basic principles of the science. In addition, to their surprise and delight, he knew each of them by name, no matter how large the class. Ken co-authored "Crystal Structure Analysis: A Primer" and "Chem One" and taught at many ACA- and IUCr-sponsored teaching schools. He was honored by many for his teaching: the ACA presented him with the Fankuchen Memorial Award in 1995.

Ken was from Dobbs Ferry, New York, where he was born 24 April 1920. He studied at Harvard and then obtained a Ph.D. at Caltech in 1947. His experiences in the Chemistry Department there, with Linus Pauling as Chairman, encouraged him to continue at Caltech as a postdoc until he went to UCLA as an Instructor. He was an Assistant Professor within a year, and became full Professor in 1960, Chair of the Chemistry Department 1965-1970 and 1990-1991, Dean of the UCLA College of Letters and Science 1971-1974, Chair of the UCLA Academic Senate 1983-1984 and Professor Emeritus after his retirement in 1989. He studied at Oxford (1965-1967) with Dorothy Hodgkin as a Fulbright Scholar and at the Swiss Federal Institute of Technology (1976-1977) with Jack Dunitz as a Guggenheim Fellow. He was also a Visiting Scientist in Moscow (1965-1966). In addition to his Presidency of ACA in 1961, he served as a member of the US National Committee for Crystallography 1960-1965 (Vice-Chair 1963-1965). These appointments illustrate his commitment to his university, to chemistry, and to crystallography.

I first knew Ken when I was a graduate student working with Dorothy Hodgkin. We were working on vitamin B12 and Ken was looking for a large structure to test his SWAC computer programs on. We sent coordinates of trial structures from Oxford, England to Ken in California, and he sent back electron-density maps which were drawn out, contoured and analyzed. Ken also studied them and we compared results. This was all done, in many cycles, by mail and I did not meet Ken in person until I was a postdoc at Caltech. We have been good friends and colleagues ever since.

Ken was a delightful person, interested in people and sports (the New York Yankees particularly) as well as science. He always had a ready chuckle and an encouraging word and will be remembered with admiration and affection by all who knew him.
Jenny P. Glusker

John (Jack) L. Moriarty
Dr. John (Jack) L. Moriarty, a physical chemist/metallurgist and long-term member of the American Crystallographic Association passed away after a sudden illness on September 24, 1997. Jack's enjoyment of crystallography and crystallographers began with his dissertation research work at the University of Iowa on synthesis and characterization of new rare earth intermetallic compounds. His thesis published in 1960, and work done as a postdoctoral research associate at Argonne from 1960-61, resulted in a series of Acta Crystallographica papers published in the1960s. Jack's care for his parents in Davenport led him to a series of industrial jobs there, as well as an extended period of high school chemistry teaching until he joined the Rock Island Arsenal in Rock Island, Illinois. There he excelled as a research metallurgist and innovator in instrumentation to automatically monitor machine tool life. A major accomplishment during the last several years of his life was providing unique expertise to bring this major Department of Defense manufacturing facility to be first in compliance with both state and federal environmental regulations. Jack was always ready to work with new ideas and approaches and went the extra mile to help the Army Research Office introduce several new ideas from academia into application. His efforts over his 16 years at Rock Island were recognized by 9 personal commendation awards, 3 recognitions for exceptional performance, a Customer's Service Award and the Commander's Quality Excellence Award in 1995. Although Jack's work and family responsibilities had taken him away from crystallography relatively early in his professional career, he and Christine often spent their vacation time at ACA meetings where he loved to socialize and much enjoyed being with his crystallographic friends. He will be missed.
Robert Reeber

1998 Crystal City ACA Meeting - Local Committee Report
It has been an extraordinary and rewarding experience for the local committee team in the past year to have this great opportunity to serve the ACA. We were proud to be able to show off our vibrant capital of the nation, Washington DC, and the unique Crystal City locations. Many attendees enjoyed the opportunity to explore various local attractions.

Tremendous team effort and collaboration succeeded in bringing our plans and arrangements to their final execution. The local committee thanks the ACA council for their continuous support and encouragement We also acknowledge the program chair, Louis Delbaere, for his wonderful collaboration. Marcia Colquhoun and her team at Buffalo headquarters also played a crucial role in our activities.

The local committee team was comprised of a group of absolutely competent, hard working and devoted scientists. Without their efforts and contributions, the meeting arrangements would never have been successful. The team members are listed alphabetically, and the specific task each was responsible for is also included.

John Barnes (NIST) - local committee deputy chair
Jeffrey Boyington (NIH) - arrangements for the poster sessions
Ray Butcher (Howard University) - recruiting and coordinating local staff
Jeffrey Deschamp (NRL) - Internet communications, the computer room and the local web page
Lawrence Finger (Geophysical Lab.) - space utilization
Judith Flippen-Anderson (NRL) - hospitality events, exhibit and hotel liaison.
Gabrielle Long (NIST) - accompanying persons program
Scott Owens (NIST) - audio visual equipment
|Charles Prewitt (Geophysical Lab.) - publicity events
Peter Sun (NIH) - local fund raising and meeting signs
Terrell Vanderah & Vicky Karen (NIST) - members at large who paved the way for the local committee team.
Alexander Wlodawer & Jerry Alexandratos (NCI-FCRDC) - ACA conference bags

Highlights of Events Organized by the Local Committee
In addition to the rich scientific program organized by the program chair Louis Delbaere, the local committee had also arranged some unforgettable events. For example, the local committee made a special effort to set up communication with the media. We had set up a press briefing room for the media and presenters to meet and exchange information. Nine presenters were selected by various symposium chairs. A total of eight reporters/science writers represented different news media attended the meeting. The meeting lasted for nearly three hours and was a notable success.

The local committee worked with the Young Scientist SIG to organize a mid-week mixer at the Janet Annenberg Hooker Hall of Geology, Gems and Minerals in the National Museum of Natural History. This Gem Hall was newly remodeled last September and is certainly one of the most magnificent attractions at the Smithsonian. As crystallographers, we were able to fully appreciate the exquisite collection of minerals and gem stones, not only because of their natural beauty, but also because of their scientific attributes. There was a welcoming ceremony there at the Baird Auditorium. Mathew Redinbo (YSSIG chair) served as the master of ceremonies. Ms. Carolyn Margolis (Chief of Exhibit Design and Development) gave a welcoming speech, followed by the ORTEP-of-the-year award given by Dick Harlow. During this mixer event, we were served with gourmet refreshments by a local caterer.

Both the opening reception and the conference banquet took place in the Hyatt Regency hotel. The opening reception provided a casual and friendly environment for attendees to mingle. Many enjoyed the nacho bar and fruit fondue. The ACA banquet menu was simply fabulous and elegant (filet mignon and the famous Maryland crabcake). During the banquet, the ACA president Penny Codding served as the MC. A very special invitation to the Scotland IUCr meeting was "performed" by Christopher Gilmore and his colleagues. Following this entertaining event, highlights of the evening featured a moving speech by our past president Jon Clardy and the Elizabeth Wood writing award to the 1998 recipient Robert Hazen.

Other services organized by the local committee team included a computer room for e-mail and software demonstrations, and a slide preview facility. In order to provide our members information about various attractions of the greater Washington DC area, an ACA Concierge desk which featured some sight-seeing information and free tickets for some special events was set up. We also had an exhibit of photographs that captured many precious moments of the past ACA meetings and ceremonies. These photos were taken by the ACA executive officer William Duax. Various people visited and shared some moments of the past with each other.

A great annual attraction of the meeting was the commercial exhibition which included more than twenty industrial companies displaying their latest development in equipment, apparatus, books, software, and services. Many attendees enjoyed the opportunity to leisurely stroll through the exhibit and meet with the exhibitors, to obtain specific information, discuss their needs, get tips for operating their instruments, and pick up souvenirs.

The meeting was an overall success. We had over 1,100 attendees, which was a record number. We were grateful for many compliments from our ACA members.
W. Wong-Ng, Local Committee Chair

50th Anniversary of the IUCr
IUCr President Ted Baker presided over the initial session commemorating the formation of the International Union of Crystallography after World War II. D.W.J. Cruickshank presented a historical view of the formation of the Union in 1946, the first General Assembly and Congress of the IUCr held at Harvard in 1948, the publication efforts of the Union, and the roles of figures such as Paul Ewald and Robert Evans in founding the Union. Cruickshank provided statistics showing how Acta Crystallographica has grown over the years, not just in the number of pages published, but also in the number of co-editors per page. G.R. Desiraju then gave a talk on crystal engineering and stressed the parallels between it and organic chemistry. Both fields require a combination of analysis and synthesis. Observing and understanding the intermolecular interactions giving rise to crystals constitutes the analytical component of crystal engineering, while the techniques used to design new solids and materials makes up the synthetic part. The following talk by I.K. Robinson showed several examples of diffraction techniques applied to the study of surfaces. He presented the problems and nomenclature associated with surface science very effectively for those of us more used to working with three-dimensional crystal structures. The final talk in the session by L.N. Johnson summarized crystallography's impact on biology and biochemistry. She presented several examples ranging from early studies of protein crystals to the large number of contemporary structures that have made X-ray crystallography a major component of structural biology.
Ronald Stenkamp

Computational Methods
Methods ... dry and technical? For sure not! The "Computational Methods" session of the ACA '98 showed many possibilities offered to crystallographers for using their data to go further. User-friendly computational tools are fast becoming available to better visualize and understand macromolecular structures, which in turn furthers easier and more accurate insights into biology.

Direct methods incorporate more and more sources of information to achieve practical results in direct structure determination (Isabel Uson, Gottingen), density modification (J Perrakis, EMBL Grenoble) and structure completion (Gerard Bricogne, MRC-LMB Cambridge).

Molecular Replacement (Steven Sheriff, BMS; Charles Kissinger, Agouron Pharmaceuticals) goes six-dimensional without taking a lifetime to complete. Multiple-wavelength Anomalous Diffraction sees its power extended by the 'Multi-MAD' strategy (Axel Brunger, Yale).

Small signals are increasingly used to learn more about the behavior of proteins at very high resolution (Ditlev Brodersen, Aarhus) and very low resolution (Bin Yu, Tallahassee). How far can we go? The anomalous signal of sulfur atoms at only ONE wavelength (SAD method) has even been used to solve a structure ab initio by classical heavy-atom phasing (Zbigniew Dauter, Brookhaven), direct methods being used only to detect the position of the anomalous scatterers!

It is remarkable that all speakers spoke less about methods in development than about already successful computational tools becoming widely available to all crystallographers. The audience could notice the dedication of all speakers to introducing new ideas through practical examples of general interest. Let us hope that this educational effort will be rewarded by the rapid uptake of new and more powerful computational tools!
Eric de La Fortelle

Transactions Symposium: Crystal Engineering
The Transactions Symposium actually got off to a roaring start on Sunday morning when Gautam Desiraju spoke during the 50th IUCr Anniversary symposium. Monday, July 20, saw a full day devoted to Crystal Engineering, with a morning and afternoon oral session, followed by an evening poster session. Attendance at all sessions was good, with a maximum audience of approximately 200 at the first oral session. The oral sessions were divided into four sections, 1) Analysis, Prediction, and Crystal Growth, 2) Applications of Crystal Engineering, 3) Hybrid Structures, and 4) Weak Interactions.

1) Analysis, Prediction, and Crystal Growth: Ray Davis started off the morning with a discussion of graph set notation in hydrogen bonded systems. Graph set analysis can describe patterns in a crystal structure and easily represent different motifs and levels of hydrogen bonding. It is now starting to be used to describe some of the weaker intermolecular interactions as well. It appears that it is now time to start statistical analysis of these motifs to provide information on which are the most common, etc.

Sally Price moved from analysis to prediction describing research efforts to predict not only individual motifs, but entire crystal structures. Thus far, programs have been successful in finding a local minimum for a known structure. However, a single structure cannot be predicted in advance because of the existence of several low energy minima with very small differences in energy. Being at or near a global minimum in static lattice energy is a necessary, but not sufficient condition for experimental crystal structures.

Donovan Chin continued the discussion of structure prediction, describing the importance of satisfying intermolecular interactions. Three dimensional motifs are easier to predict than flat structures, owing to the fit of individual layers. Tayhas Palmore ended the early morning session with a talk on crystal growth. Imaging crystals during growth using atomic force microscopy allows one to analyze the topology and correlate it with crystal growth. Understanding this growth process will enable control of crystal growth leading to self-assembly of higher density materials using organic/inorganic interfaces.

2) Applications of Crystal Engineering: It was noted that the promise of crystal engineering is in the applications of the new materials developed using the tenets of the emerging field. Robin Rogers began the applications section with information on formation of porous solids using inorganic coordination polymers. Neutral, cationic, and anionic networks can be engineered to produce a new generation of ion exchange or absorptive materials. Abe Clearfield elegantly illustrated the application of crystallography to understanding the mechanism of inorganic ion exchange materials, such as those considered for nuclear waste clean-up. With understanding comes the knowledge to tailor selectivity and capacity into the inorganic solids, leading to a new generation of ion exchange materials.

Bruce Foxman led us away from separations science into synthetic chemistry. The solid state reactivity of tailored materials can be manipulated using crystal engineering. Using structure analogy by comparison with the CSD and taking advantage of hydrogen bonding and metal reactivity, materials can be designed which lead to a single stereoselective product via solid state reaction. Kumar Birdha from Mike Zaworotko's group finished the morning with a discussion of trimesic acid as a supramolecular synthon via its hydrogen bonding patterns. Control was demonstrated over bilayer formation and guest inclusion.

3) Hybrid Structures: The afternoon session started with Christer Aakeroy's example of bad engineering, the Verrazano Narrows Bridge, and led into a discussion of good crystal engineering using hybrid organic/inorganic synthons. Using both charge assisted hydrogen bonding and metal ion coordination, nicotinamide was shown to form lamellar organic sheets separated by rigid pillars when coordinated to Ag(I). Jon Zubieta continued the exploration of polymeric ligand coordination polymers, but this time stabilized by large inorganic anions (e.g., molybdenum oxide clusters). The design strategies don't require total predictability, but do require structure/function relationships.

John MacDonald introduced ionic hydrogen bonding and the use of aggregates rather than molecules to predict the overall structure. He discussed the need for a robust, but flexible motif, given the difficulty in packing rigid molecules. An important aspect of this work is the idea that one can use crystal engineering to get to molecular functionalities which are difficult or impossible to reach by organic synthesis. Len McGillavary (from Jerry Atwood's group) provided an elegant example of engineering molecules that are difficult to synthesize. Multicomponent architecture was demonstrated by the extension of the rim of resorciarenes by hydrogen bonding to pyridines. The extended structures were shown to include molecules as would be expected for the covalently bonded analogs.

4) Weak Interactions: Each of the speakers objected to the use of 'weak interactions' to denote their topics, noting that many of the interactions discussed were in fact stronger than conventional hydrogen bonds. Functional group interactions and new kinds of weak intermolecular interactions were the focus of Si Blackstock's talk. Donor/acceptor bonding was combined with weak CH-O hydrogen bonding in heterocyclic N-oxides. These strong hydrogen bonding acceptors have the R22(8) dimer as a key mode of self assembly supporting the formation of periodic domains of precise motifs. Bill Pennington engineered molecules using charge transfer interactions with N-I interactions forming extended chains, dimers, or even simple adducts. I2 was observed to be bridging, terminal, or even amphoteric. The six-fold phenyl embrace was introduced to the audience by Thomas Steiner. It was explained that the interactions are ubiquitous in the CSD and quite capable of directing overall structure. Several examples were provided where these interactions led to molecular columns.

Gautam Desiraju provided a stimulating wrap-up to the day's talks, leaving the audience with a lot to ponder. The core of crystal engineering was described as an attempt to get essential data important to predicting crystal growth and structure. However, while computational aspects have come a long way and experiments have provided a large number of crystal structures, what does it all really mean? The audience was challenged to devise new methods for getting the essential data from the myriad of structures now appearing. The structures must be compared, analyzed, and codified. Putting something in the CSD is not enough and crystal engineering will advance much faster once methods for intelligent comparison of structural data are available. Unless methods are available soon to handle this, instead of the fulfillment of the exciting promise of crystal engineering, we will simply drown in a sea of crystal structures!
Robin Rogers

Small Angle Scattering for Studying Complex Materials: A Report from the Small Angle Scattering Special Interest Group of the ACA
Small-angle scattering of neutrons and X-rays offers unique pieces of information that can be key to integrating structural data from other methods, including high resolution crystallographic and NMR methods, electron microscopy, etc, in order to understand complex materials. We are seeing significant growth in the use of small-angle scattering techniques that is being driven both by technology development as well as by the compelling scientific questions that now are being asked about the structural and dynamic properties of matter, especially in biomolecular systems. On the technology development side there have been continuing advances in synchrotron and neutron source development that is delivering higher flux beams, as well as more and better instrumentation available to the general user community. These capabilities facilitate faster data acquisition on smaller samples. At the same time, advances in biotechnologies and chemical synthesis have made it easier to make samples, including those with specific deuterium labeling to take advantage of neutron contrast variation methods. Another significant technology driver has been the ease of access to significant computational power, facilitating algorithm development and modeling capabilities not previously accessible to the general user.

At this year's meeting of the ACA in Washington, two sessions were organized, the first on combining scattering methods with diffraction and NMR to solve complex problems, and the second on modeling small-angle scattering data.

Two of the presentations on combining scattering methods with other techniques to solve complex problems focused on the use of neutron contrast variation methods with small-angle scattering to understand biomolecular interactions in the regulation of enzyme activity. Jinkui Zhao presented small-angle scattering studies of the cAMP-dependent protein kinase, the prototypical kinase that serves as a model for the ubiquitous kinase family whose role is to attach phosphate groups to other proteins in order to regulate their activity. Neutron contrast variation studies with specific deuterium labeling revealed the quaternary structure of the holoenzyme, which consists of two regulatory cAMP-binding domains and two catalytic domains. By combining the information about the shapes and dispositions obtained from the small-angle scattering studies with high resolution crystal structure data on the isolated components, the interactions and conformational transitions involved in the activation mechanism were revealed. Jill Trewhella presented the results of similar studies on the activation mechanism of another model kinase, the muscle enzyme myosin light chain kinase. This kinase is activated via interactions with the calcium receptor calmodulin. The combination of high resolution crystal structure data, solution NMR, scattering with contrast variation, and modeling have revealed the structures and interactions of this kinase with its regulatory partner throughout the activation process.

Roland May presented the results of small-angle neutron scattering and contrast variation studies of the structure of the chaperonin proteins that aid in protein folding by unfolding "misfolded" proteins. May and colleagues modeled the 3D solution structure of a bacterial GroEL-GroES chaperonin using neutron scattering contrast variation data from the complex in which one component was deuterated and X-ray crystal structure data on the isolated components. Significant changes in the conformations of the components within the complex were identified that provide a critical basis for kinetic studies of GroES-GroEL and its interactions with substrate (a misfolded protein) in solution. Sebastian Doniach discussed the application of high intensity synchrotron radiation for studying ab initio protein folding (in the absence of chaperonins) using time-resolved small-angle scattering to monitor protein compaction and changes in hydration as a function of the folded state. These studies are providing critical information on the nature of folding intermediates and the dynamic transitions undergone by a polypeptide as it proceeds from an unfolded to a folded and functionally competent native state. The key for the future of small-angle scattering applied to protein folding will be in pushing some of these measurements to shorter and shorter time-scales (1-10 ms) with smaller sample volumes. New developments in micro-synchrotron beams and lithographically fabricated mixing cells currently being explored at CHESS and Princeton have great potential to contribute to these advances.

Sebastian Doniach also described new results on prion association that is implicated in neurodegenerative diseases such as Bovine Spongiform Encephalography in cows and Creuzfeld Jacob disease in humans, while Thiyago Thiyagaran discussed small-angle scattering and NMR studies of aggregation of beta-amyloid peptides that form the proteinaceous lesions called amyloid plaques that are diagnostic of Alzheimer's disease. Small-angle scattering is an ideal tool for studying the structure and kinetics of formation of these aggregate states, providing insights into the molecular pathology of these devastating neurodegenerative diseases.

The final presentation in the session on combining small-angle scattering methods with other data to study complex systems moved away from biological systems and was given by Shaoxu Han who described a combination of in situ NMR with small- and wide-angle scattering data aimed at understanding the hydrothermal synthesis of zeolite NaA. The small-angle data revealed details of the gel transformations during the aging process, while the wide-angle data revealed details of the crystallization process. NMR was used to monitor specific chemical species.

The session on modeling small-angle scattering data dealt with issues in modeling data from biological structures to materials and dislocations. Dmitri Svergun presented an eloquent description of a suite of programs that he has developed for analyzing small-angle X-ray and neutron scattering data in terms of the structures of monodisperse macromolecular systems, aimed predominantly at biological structures, as well as polydisperse systems more common in synthetic polymer materials. These programs are designed to be user friendly and are available as executables for unix or PC platforms (svergun@embl-hamburg.de). Norman Berk discussed model independent approaches to analyzing surface biological structures from reflectivity data. These methods are particularly useful for studying membrane mimetic, self-assembled lipid layers and Langmuir-Blodgett films. The reflectivity approaches are also being pursued for the difficult to study polypeptides embedded in model membranes.

Jan Skov Pedersen discussed the applications of Monte Carlo simulation methods to model micellar and polymer systems for which there are no useful analytical expressions for the scattering function. He described approaches for handling giant worm-like micelles, semi-dilute solutions of polystyrene, polystyrene stars, and block co-polymer micelles. John Zwanziger described a reverse Monte Carlo algorithm to model glass structure from combined NMR with X-ray and neutron diffraction data. He utilized the relationships between NMR distance measurements in the solid state, specifically second moments, and the pair distribution functions of the coupled nuclei. Paul Schmidt described a technique for using small-angle X-ray and neutron scattering to study the structure of independently scattering, randomly oriented non-crystalline systems of interacting scatterers with structure on length scales from 10 - 20,000 Å. His approach uses the analytical expression from Debye (1915, Annalen Phys. 46, 351) and he gave examples of its use for analyzing data from carbon black soots and silica xerogels. Andrew Allen described studies of multi-component, concentrated, anisotropic microstructures using multiple small-angle neutron scattering (MSANS) and Porod scattering. He described using the MSANS approach to study plasma-sprayed ceramic deposit microstructures containing different classes of void components, and the results were directly related to electron microscope images and other property measurements. The final presentation in the modeling small-angle scattering data session was from Gabrielle Long who described ultra-small-angle X-ray scattering (USAXS) by dislocations in single-crystal aluminum as a function of plastic deformation.

Small-angle scattering is ideal for monitoring conformational transitions and dynamic processes in non-crystalline states. The studies of biomolecular complexes described here are in general too large for solution NMR structural analysis, and they show conformational flexibility that is critical for function and makes crystallographic studies difficult if not impossible to characterize each step in a dynamic process such as an enzyme activation mechanism, protein folding, or aggregation processes. Clearly, many advances in materials and polymer research also are being made with small-angle scattering. The techniques of neutron contrast variation, as well as more sophisticated sample environments have been continuing to develop and expand the potential for materials research with these tools.
Jill Trewhella

Direct Phasing of Macromolecules
It was to a packed room that lecturers in this session described the astonishing progress that has been made in the direct phasing of macromolecular structures. Shake-and-Bake and the SHELX "half-baked" approaches continue to dazzle us with their successful ab initio determination of larger and larger proteins. As reported by Hauptman, Sheldrick, Weeks and Schäfer, structures containing as many as 2000 non-hydrogen atoms are being solved routinely by these methods, an accomplishment that only a few years ago was viewed as impossible. Further robustness and efficiency in these phasing algorithms were also reported, stemming to the exploration of different computational strategies. Recognizing that these successes depend on the availability of high resolution data, significant effort has been focused on expanding the viability of the direct methods to lower resolution data. Gilmore, in particular, described results from the maximum entropy-likelihood method which outlines a possible path to breaking the resolution barrier.

Remarkable successes were also reported on the MAD front from Smith and Howell, with larger and larger selenomethionine labelled proteins being solved. Direct methods procedures have proven to be extremely useful in tackling large proteins with substructures containing as many as 30 Se atoms. There is every reason to believe that much more will come from the combined MAD-Direct Methods approach.

The last part of the session turned to low resolution data and the description of methods tailored to tackle complex problems. Podjarny described the application of the Few Atoms Model (FAM) to the 50S Ribosomal Particle; Dorset showed that using "glob" scattering factors with projected electron diffraction data, accurate phase determination at low resolution was obtained for several membrane proteins; Miller reported on a procedure based on the genetic algorithm paradigm, which was developed for the ab initio determination of low resolution phases of icosahedral viruses.

At the end of the day, the participants in this session were left with great hopes for the future but, even more important, a very sophisticated and efficient set of tools with which to solve increasingly challenging problems.
Suzanne Fortier

Publication and Presentation of Crystallographic Results
This session focused on some practical matters: tools, techniques, and some philosophy about the presentation of crystallographic results. The first lecture, by Dave Duchamp, showcased his program CrystMol, a software package for the display, analysis, and manipulation of crystal structures that is currently designed for use on Macintosh computers. Coordinates are input using CIF or PDB files. Graphics are output as PICT or 3DMF; the latter can be used for 3-D Internet publishing. A special notebook feature allows for remarks to be logged by the user as the graphics files progress in their creation. Another feature is to set up disorder in CIF's. Atoms and molecules can be displayed using ball and stick, line, thermal ellipsoid, space filling and combinations of these, and rotated, translated, and zoomed in on. Crystal packing is another feature.

Although CrystMol is not a commercial product, small contributions for its use are welcome. The first version for beta testing will be ready this fall, and he solicited volunteers for the testing (email: JDuchamp@aol.com).

Ethan Merritt presented a variety of graphics that were made much more effective by the use of rasterizing effects using the program Raster3D. The rendering program is not dependent on any particular input program. It allows for various lighting and shading effects, as well as tools such as transparent helices and cylinders rather than ribbons to display the effects of protein folding. Solid thermal ellipsoids, sometimes combined with electron density plots, were also shown to be quite effective in showing the effects of thermal anisotropy. Some additional information is available at the web site http://www.bmsc.washington.edu.

Steve Heller displayed the format and range of possibilities for electronic publishing via the new Internet Journal of Chemistry. Among the advantages for this new form of communication is the ability to convert units on the fly so that quantities of interest can be standardized from paper to paper for easy comparison. Authors are hotlinked so they can be contacted easily. References can be clicked on, and the reference pops up at the bottom of the screen. For crystallographers, there is the obvious advantage conferred by the use of 3D graphics and real time rotation. The disadvantage to this type of publishing is the lack of a printed document. Archival questions remain to be worked out. However, here is a new way to think about how we communicate and how new technologies can be used to our advantage.

In Tom Brett's talk some of the basic principles of making effective presentation graphics for both seminars and posters were reviewed. Some of the suggestions were, draw attention to the work by use of good composition; use the elements of color, line and perspective to convey different points. For example, cold/warm colors are useful for showing thermal motion, while color hues help to identify different atoms. Stronger and weaker lines can elucidate disorder. Different rendering styles can also be effective.

Kathy Duffy of ACS Journals offered some valuable tips in the preparation of graphics for publication. As she pointed out, in the 140,000 pages of ACS journal articles, there is competition among authors, and the use of good graphics is a principle method for attracting readers. While printed text is quite straightforward, graphics must be digitally scanned and combined with the text, and for this to be successful the guidelines must be followed. These guidelines are available from the Notice to Authors, the Editorial office, and the publisher of the various journals, as well. There is the ACS Style Guide and brochures available from the editorial offices. In addition, there is the web site http://pubs.acs.org/instruct/illus.html for web journals. The key advice is to use high quality originals directly from a laser printer (not copies). If possible, make the original 3.25 inches wide (single column width) in order to identify potential surprises when it is reduced. Shading can be quite different when the drawing is reduced. Photographs will lose contrast and will not be as clear. The cost of using color has been reduced to $300 per graphic. While RGB is used on monitors, CMYK process is used in print, and the colors can be different. Similar colors should be avoided. If soft copy graphics are submitted they should be either TIFF or EPS. For additional advice on digital graphics, a person to consult is J. Yurvati at 614-447-3665.

Greg Petsko's lecture, on the craft of lecturing, was truly inspiring and received enthusiastic applause. To summarize his points: 1) Tell a story; 2) Tell only one story; 3) Tell the audience three times - tell them what you're going to tell them, tell them, and tell them what you told them; 4) Give a minimum of 25-33% background material; 5) Vary the pace of the talk and use no more than 1 slide/minute and at least 1 slide/2 minutes; 6) Check to be sure that all your slides/overheads can be clearly seen from the back of a large room that is not very dark so that you can still make eye contact with your audience. The minimum font size is 28 point, bold or even extra bold; 7) For complex subjects, try to find the right metaphor; 8) Be yourself, and use humor only if it's natural to you; 9) Don't read your slides but do summarize them in different words; 10) Be gracious, give lots of credit; 11) Use colorful language and try to blend in analogies with every day life; 12) Don't use gimmicks like two projectors that might get in the way of clarity.
Marilyn Olmstead

Electronic Materials
This session, organized by Dave Cox and Winnie Wong-Ng highlighted state-of-the-art studies of the structures of materials having interesting and useful electric and magnetic properties. Many of the studies included both X-ray and neutron diffraction experiments. The current dearth of neutrons in the U.S. represents a real handicap to improved understanding of materials.

Eugene Antipov (Moscow State) demonstrated that variation in the Tc of HgBa2CuO4+d (Hg-1201) and HgBa2CuO4Fd can be achieved by changing either the carrier concentration (extra O or F content) or the pressure. Both the oxygen and mercury partial pressures must be carefully controlled during synthesis to prepare pure material. He recommended XeF2 as a "gentle" fluorinating agent. The Tc is determined by the carrier concentration and the in-plane Cu-O distances; the axial distances are less-important. It should be possible to mimic the effect of pressure on Tc by preparing thin films on a "small" substrate.

The very complex phase diagrams of La2NiO4+d, La2-xSrxNiO4+d, Sr3RhO4+d, and Sr2IrO4+d have been investigated using synchrotron X-ray powder and neutron single crystal diffraction by D.J. Buttrey (Delaware). The hole content can be controlled by doping with Sr, O, or both. Charge, spin, and oxygen defects order as a function of conditions.

Grit Böttger (ETH Zurich) described magnetic ordering in the "247" systems R2Ba4Cu7O15-d (R = Er and Dy). This structure consists of alternating blocks of "124" and "123", and the Tc is a function both of the O content and the number of stacking faults. Using low-temperature neutron diffraction, three-dimensional magnetic ordering was detected in the Er system with O14.92; the ordering is ferromagnetic along b and antiferromagnetic along a and c. In the O14.3 compound, there is both long- and short-range one-dimensional magnetic ordering. Dy systems having two different oxygen concentrations exhibit long-range three-dimensional antiferromagnetic ordering.

An excellent example of the application of bond valence calculations to understand structural details was supplied by Tony Santoro (NIST), for (Ba0.875Sr0.125)RuO3,

BaRuO3, and Ba3MRu2O9 (M = Fe, Co, Ni, Zn, and In). The bond valence sums around the cations are not very "good", indicating compression around the Ba/Sr and expansion around the Ru. Tony generated ideal structures by the use of sphere packings, connectivity, and expected bond distances, then developed algebraic expressions for the bond distances as a function of the cell dimensions and atom coordinates. These equations provided a way to understand how to modify the structures to satisfy atomic valence requirements, and led to identification of geometrical factors which play roles in the formation of these compounds.

Pat Woodward (BNL) summarized structural and magnetic phase transitions in several Ln0.5A0.5MnO3 (Ln = trivalent lanthanide, A = Ca2+, Sr2+) systems which exhibit colossal magnetoresistance (CMR). The tilt of the MnO6 octahedra affects the overlap of the Mn eg and the O orbitals, and thus the properties. Spin, charge, and orbital ordering are observed. The properties are the result of a delicate balance among several different structural effects.

Charlie Torardi (DuPont) described ferromagnetic ordering in the layered compounds M(ReO4)2 (M = Mn, Fe, Co, Ni, and Cu). These structures consist of layers of octahedral M2+ and tetrahedral perrhenate; unshared perrhenate oxygens interpenetrate adjacent layers. The Fe, Co, and Ni compounds exhibit 2d and 3d ferromagnetic ordering at low temperatures. The magnetic ordering differs from the antiferromagnetic ordering observed in the M(OH)2; the hydrogen bonding paths between the brucite layers apparently play a role in the magnetic ordering.

A "change of pace" was provided by Wally Cordes (Arkansas), who described crystal engineering of organic solids based on heterocycle radicals, such as (1,2,3,5)-deselenadiazolyl oxidized with iodine. Such compounds stack with parallel layers 3.5 Å apart, and iodine disordered in channels. Compounds containing bridged radicals can be prepared; these bridges decrease the side-to-side contacts.

R2Fe17 compounds (R = lanthanide) are promising candidates for the next generation of hard magnets. The magnetic properties of these materials can be enhanced by either interstitial or substitutional modifications. H. Luo (Missouri-Columbia) described neutron diffraction studies of both ordered and disordered systems.

L. A. Bendersky (NIST) described a group of ternary BaO:TiO2:Fe2O3 phases having structural features corresponding to natural magnetic multilayers. These compounds have alternating layered slabs of different thicknesses and periods. One of the slabs can be considered as a dielectric spacer for the high-Fe slabs, which are magnetic.

Improved thermoelectric materials may result in more efficient refrigerators and powder sources with no moving parts. Brian Sales (ORNL) discussed filled skutterudites LnFe3CoSb12 in which the lanthanide is a "rattling" atom, which results in low thermal conductivity and is electronically isolated from the conduction bands of the antimonide framework. The mean free path of phonon scattering is about 8 Å, comparable to the Ln-Ln distance.

Extensive studies of the perovskite relaxor ferroelectrics Pb(Mg1/3Nb2/3)O3 have led to a space charge model for explaining their properties. Peter Davies (Pennsylvania) described a series of experiments on Pb(Mg1/3Ta2/3)O3 relaxors, the results of which are not consistent with the space-charge model, but indicate a charge-balanced random site model. The ferroelectric coupling along 111 is frustrated by the random occupancy of the B sites. There is a narrow temperature window in which it is possible to increase cation ordering, and the ordering can be stabilized by the addition of small amounts of Zr or Ce.

Tom Vogt (BNL) described the electrochemical expansion and contraction of AB5-type alloys used in nickel-metal-hydride batteries. Current electrodes contain expensive Co. A neutron diffraction study of LaNi3.55Co0.75Mn0.33Al0.30, in which the Ni was a "null alloy" of 37.6% 58Ni and 62.4% 62Ni, indicated a preferred site for Co substitution. Substitution in this site alters the compressibility along the c-axis, and influences corrosion. These results suggest ways to develop lower-cost non-Co alloys for use in such batteries.

An extremely elegant series of experiments to determine the polarization charge density in GaAs were described by Ulrich Pietsch (Potsdam). In these experiments, the very small intensity changes in certain reflections caused by application of an external electric field were measured at several wavelengths near the Ga K absorption edge. The measurements needed to be repeated several thousand times to obtain adequate statistics. The external field increases the covalent character of the bonds in one direction, and decreases it in others.

Anand Subramony (U. of Washington) characterized three new high-temperature polymorphs of the well-studied compound potassium dihydrogen phosphate (KDP). The structures were determined by studying single-crystal islands within polycrystalline fragments; these islands were metastable at room temperature. A P21/c polymorph has a two-dimensional hydrogen bonding similar to that in TlH2PO4. A P1-bar form is similar to the room-temperature tetragonal structure. A Cc polymorph also has two-dimensional hydrogen bonding, but both the a- and c-axes are doubled compared to the P21/c form.
James Kaduk

General Interest Group Sessions
The first General Interest Symposium consisted of seven variations on the theme "Ways of Thinking about Structures". First, Mark Spackman presented a new way of defining boundary surfaces around the molecules in a crystal structure. He called them Hirshfeld surfaces. Inside the surface the molecule contributes electron density which is equal to or greater than the total electron density from the entire crystal. Hirshfeld surfaces generally follow the classic van der Waals envelope except in regions of strong molecular interactions. Most remarkable were the surfaces for oxalic acid which are quite different in the two crystal forms of oxalic acid dihydrate.

Yuri Abramov reported experimental and theoretical studies of the charge density in crystal structures of four D,L amino acids (histidine, proline hydrate, threonine and aspartic acid). Electrostatic properties were derived from the charge density. They included a topological study of the charge density, the Laplacian at bond critical points and the electrostatic energies of molecular interactions. Emphasis was on the bond critical points for the hydrogen bonds, including weak C-H..O interactions.

Next Eric Bruton described results of a Cambridge Structural Database search for hydrogen bonds of the type D-H...X-M in which M is a transition metal, the acceptor X is F, Cl or Br and the donor D is C, N or O. The search included bifurcated interactions. Trends were identified, such as shorter H...X distances when X-M is more polar. Also distances in bifurcated systems are longer. The results are consistent with an electrostatic theory for hydrogen bonding.

William Ojala (spokesperson for a group from the Twin Cities) presented results from structure determinations of a class of benzylidineanilines having a nitrile at one end and a halogen at the other. The crystal structures are acutely sensitive to the switching of the two substituents. These lath-shaped molecules form end-to-end intermolecular interactions of Lewis acid-base type, such as X..NC and CN..X where X is Cl, Br or I. The molecules form chains which further assemble as sheets but, especially when X is Br or Cl, there is disorder and polymorphism.

Highly complex tiling patterns arise in the crystal structures of many intermetallic compounds that contain a large amount of Al. Earle Ryba showed many of these tiling patterns. Often they contain pentagons which share edges and are also connected by means of quadrilaterals and triangles. The tiling is two-dimensional and conforms to a normal crystal lattice. This is achieved by small distortions of the polygons from regularity. It has been difficult to derive a rational basis for this class of layer structures.

Carroll Johnson presented crystallographers with a new way to look at our familiar space group diagrams. The crystal asymmetric units are represented as nuclei with overlapping thermal ellipsoids and for each of the 24 cubic space groups, the four Ps are derived (peaks, passes, pales and pits) together with their connecting pathways. The asymmetric volume of the unit cell is transformed in order to bring out the symmetry of these topological properties. Carroll pointed out that in the transformed space group diagram, there is a Heegaard surface that separates the peaks and passes from the pits and pales.

Finally, John Konnert described the modelling of molecular features observed on the (110) face of a lysozyme crystal. These features were observed using an atomic force microscope. Model variables were the reported atomic coordinates and their van der Waals radii and also the shape and dimensions of the probe tip. The model image could be fitted to the observed image with a correlation coefficient of 0.91. To obtain this agreement, it was necessary to displace molecules at the surface by about 6 Å from their positions in the bulk structure.

The second session of the General Interest Group took place on the afternoon of the last day (Thursday) of the meeting. Richard Deslattes started with a discussion of the role of X-ray crystal-density (XRCD) measurements in atomic-weight determinations. The method might be especially appropriate for multi-isotope elements having variable isotopic abundances. Deslattes concluded, however, that other methods for determining atomic weights and isotopic abundances are more satisfactory and/or cheaper.

Thomas Gnaeupel-Herold spoke about the possibility of using powder (polycrystalline) samples to determine single-crystal elastic moduli. Scattering angles of a group of reflections hkl are measured as a function of applied stress and then used to calculate strains. Conversion of the strains to single-crystal elastic moduli requires assumptions about grain interactions in the polycrystalline sample. Several models were considered. Results so far are encouraging.

Philip Coppens presented his group's work on light-induced metastable linkage isomers of trans-(Ru(NO)X(py)4)2+ and (Ni(C5Me5)(NO)). Under constant laser irradiation the NO ligand isomerizes from ordinary monodentate coordination to a hapta-2 isomer.

Ed Stevens showed the power of the new CCD diffractometers by presenting two refinements (one for TTF, the other for TCNQ) that used ca. 500,000 reflections each. Data measured at several temperatures were refined simultaneously; variables included independent sets of positional and displacement parameters for each temperature and a single set of multipole terms to model the electron-density distribution. The fit of the joint (multi-temperature) model was as good as the fits of the single-temperature models.

Continuing with the theme of CCD diffractometers, Damon Parrish showed that diffraction peaks from a crystal with an 80 Å axis can be resolved satisfactorily with Mo radiation if the crystal-detector distance is increased. Anthony Martin spoke about using multi-temperature measurements to determine thermal-expansion tensors.

Rusan Sanishvili from Argonne National Lab closed the session by describing the amazing feat of having measured a satisfactory data set for a protein in 12 minutes. He used synchroton radiation and a CCD diffractometer. Elapsed time including crystal mounting was 45 minutes. Data collection can be done so quickly that initial screening for crystal quality can be skipped. It is simpler to measure a full data set for each crystal mounted.
Carol Brock

Structure Based Drug Design
The session opened to a standing-room-only crowd with introductory remarks by Howard Einspahr (Bristol-Myers Squibb) that highlighted the areas where structural information impacts the drug-design process in the modern pharmaceutical company. These areas are currently the lead-finding and lead-optimization phases and, while the progression through development and clinical trials to regulatory approval and the market may require the contributions of hundreds if not thousands, these two earliest phases begin with the efforts of tens of collaborators, a scale that is also within the range of dedicated laboratories in academic settings.

The opening speaker was Wim Hol (University of Washington), who reviewed the work in his lab on inhibitor design against tropical disease targets, cholera toxin and glyceraldehyde-3-phosphate dehydrogenase. Design efforts have achieved micromolar potencies against the latter enzyme.

Paula Fitzgerald (Merck) reviewed the development of inhibitors of HIV-1 protease as treatments for HIV/AIDS. The intense effort on HIV protease has been a particular success story for the application of the techniques of structure-based drug design to a critical clinical problem. A review of the structure-design strategies employed at a sampling of different pharmaceutical companies reveals that it was possible to identify potent inhibitors of the enzyme from a variety of different structural classes. The hard part of the process was finding potent inhibitors that had the desirable combination of potency, solubility, oral bioavailability, serum lifetime, and safety, but this was achieved in a number of different ways, and four structurally distinct compounds are now approved for use by the FDA.

Ming Luo (University of Alabama at Birmingham) described the effort at UAB to design effective inhibitors of the influenza virus neuraminidase, which has achieved nanomolar potencies.

Amy Swain (Hoffman-La Roche) presented four crystal structures of an MHC class II molecule (DR4) with peptidomimetic compounds in complex with a superantigen (SEB). The group of compounds illustrated optimized interactions between inhibitor substituents and the protein and showed that dipeptide mimetics preserved the essential backbone atoms of the compound while disguising it from proteases. A previously unidentified space was observed within the binding cleft which, if exploited, may provide potential for the design of a more potent series of compounds.

Sherin Abdel-Meguid (SmithKline Beecham) highlighted some of the lessons gained from experience in structure-base drug design during the last decade. He emphasized the importance of experience, synthetic accessibility, water molecules, solubility of ligands, electrostatics, iterative design, maximizing interactions, starting the design from liganded structures and the importance of having a dedicated molecular biology and protein purification team.

Jon Robertus (University of Texas) described efforts to identify and design inhibitors for the class of ribosome-inhibiting proteins including ricin and shiga toxin. A key observation was that pterin compounds bind to the active site of ricin in a high-energy tautomeric form. This suggests that programs aimed at virtual drug screens, or de novo design, should include tautomers of test compounds, which may have quite different electrostatic properties than the most common solvent state form.

Corey Strickland (Schering-Plough) reviewed the early stages of his structure work in support of the search for useful inhibitors of Ras farnesyl transferase, an important oncology target.

Jerry Alexandratos (NCI-Frederick) described progress in studies of inhibition of ASV integrase and showed that an inhibitor of HIV integrase activity binds not in the proposed catalytic site of ASV integrase, but rather in a nearby site formed by symmetry-related molecules that is hypothesized to modulate binding in the active site.

In the final talk of the session, Ossama El-Kabbani (Monash University) described studies of two related enzymes, aldose and aldehyde reductases, that have been identified as potential drug targets to alleviate some of the degenerative problems associated with the complications of diabetes. To date, none of the currently available inhibitors has been approved for clinical use due to undesirable side effects. Based on the recent ternary structures of the enzymes, new inhibitors mimicking the nicotinamide-ribose portion of NADPH have been designed that possess components of both coenzyme and inhibitor molecules and utilize the maximum interactions between the enzymes and the bound ligands.

The help of the presenters in the drafting of this report is gratefully acknowledged.
Howard Einspahr

Amorphous Materials Sessions
Despite its abundant and varied occurrence, the amorphous state of matter still poses a great challenge to structural characterization techniques. During the 1998 Annual Meeting of the ACA, the Amorphous Materials Special Interest Group focused on selected aspects of this field. The SIG organized one workshop and three symposia. The subject of the workshop, which was held on Saturday, July 18, was the numerical modeling of disordered materials. It consisted of four lectures, two of which dealt with the interpretation of experimental diffraction data, while the other two described how structural information can be obtained using modeling techniques that are based on reliable representations of atomic interactions. Prof. P.H. Gaskell, from Cambridge University in the U.K., demonstrated how the knowledge of chemical bonding constraints can be used to help interpret low-Q diffraction data. Dr. R. McGreevy, from the Studsvik Neutron Research Lab in Sweden presented his reverse Monte Carlo method. In this method, the atomic configuration which produces an experimentally determined structure factor is derived by continually shifting the atomic coordinates of a numerical model, until the structure factor of this model matches the experimental one. Profs. D. Drabold, from Ohio University, and P. Vashishta, from Louisiana State University, each illustrated atomic scale simulation methods. Their presentations juxtaposed the relative merits and mutual reliance of first-principle electronic orbital calculations, which to date provide the most accurate interatomic forces, and multi-million atom molecular dynamic simulations, based on semi-empirical potentials, which are required to uncover extended-range structural characteristics and the mechanisms of materials processes.

The workshops were organized by Prof. J. Zwanziger from Indiana University, who also organized the symposium on non-oxide glasses, that was held on the morning of Thursday, August 23. Dr. W. Dmowski from the University of Pennsylvania organized a symposium on Surfaces, Interfaces, and Films, held on August 22. This symposium focused on the characterization of structural disorder in narrow interfacial regions. Presentations provided an overview of applications of state-of-the-art techniques ranging from small-angle X-ray, to synchrotron X-ray scattering, to neutron reflection.

While the most common inorganic glasses consist of a mixture of oxides, there are several groups of materials that can be classified as non-oxide glasses. Two representative examples of such systems were given during the symposium on Thursday morning by Dr. B. Aitken of Corning, Inc., and Dr. R. Busch from the California Institute of Technology. Dr. Aitken illustrated the high promise that some non-oxide glasses hold for photonic applications. Dr. Bush described bulk metallic glasses, a recently discovered class of materials, typically consisting of five or more components. These alloys remain amorphous without requiring the extreme quench rates typically associated with metallic glasses. Hence, large bodies of metallic glass can be fabricated, and advantage can be taken of the outstanding mechanical properties of such systems for structural applications. Other talks during this session concentrated on the structural characterization of non-oxide glasses, using neutron scattering and NMR techniques.

The third symposium was held on Thursday afternoon, and was entitled: "Colloids and Gels." This symposium was organized by Prof. J. Kieffer from the University of Illinois and focused on the structural characterization of pores, networks, and aggregate clusters in colloidal suspensions and gels. Strong emphasis was put on small-angle X-ray and neutron scattering techniques, but rheology and the measurement of mechanical properties were also discussed in this forum.

Overall, the symposia and workshop provided a very useful sampling of the current issues in the field of amorphous materials, as well as of the scientific approaches that are being taken to advance the understanding of this state of matter. The various lectures and presentations attracted audiences with diverse backgrounds. Strong attendance reflected a high level of interest in this subject area.
John Kieffer

The State of the Art in Fiber Diffraction
This was a lively session, attended by a maximum of about 60 and a minimum of about 25. Progress in the state of the art in the last two years since the symposium sponsored at the Seattle IUCr has been considerable, as reported by the speakers this year. Experimental advances in high brilliance sources, especially favoring small samples, are complemented by advances in software, mainly providing packages of programs which make data collection, correction, and analysis by a variety of recognized techniques easily accessible to the fiber diffractionist, whether synthetic or biological in nature.

Fiber diffraction has also been unusually active this year outside the ACA. Perhaps a major reason for this was the Third Fiber Diffraction Workshop held at Jenny Wiley State Park in Kentucky in October of 1997, organized by Rick Millane (Purdue)with assistance from Gerald Stubbs (Vanderbilt). These workshops are held every four years, and although the number of participants tends to be rather smaller than, for example, the corresponding workshop run annually by CCP13 in Britain, they are always informative and intellectually stimulating. This one was particularly helped by the presence of an unusually large contingent from Europe (seven from Britain and one from Italy). It was clear from the various speakers that synchrotron radiation is becoming extremely important in fiber diffraction; fiber diffractionists benefit particularly from the fact that synchrotrons allow them to use exceptionally small diffracting samples. Magnets (typically 9 Tesla and above, such as are used in NMR) are featured more and more in accounts of preparation of fiber specimens. Software is improving, and perhaps more significantly, the fiber diffraction community is becoming more coherent. Tthere is much more collaboration in the development of fiber diffraction software than there was even four years ago. All present agreed that international collaboration in fiber diffraction will continue to increase, that fiber diffraction is robustly healthy, and that the Fiber Diffraction Workshops will continue to be an important component of the community's activities.
Wade Adams

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ACA Symposium on New Directions in Neutron Scattering Instrumentation for Structural Biology
The all day symposium on "New Directions in Neutron Scattering Instrumentation for Protein and Membrane Crystallography" was held at the annual meeting of the ACA in Arlington, Virginia, on July 23rd. The aims of the organizers, Benno Schoenborn and Bob von Dreele (LANL), were to promote and to make provision for, new technical developments which promise to broaden the application of neutron diffraction in structural biology. Ten speakers presented recent accomplishments in the application of neutrons to Biology using a variety of different diffraction techniques to an audience of about 50.

The two sessions, chaired by Robert Knott (ANSTO) and Bob von Dreele (LANL), included three talks that described experiments carried out on the new LADI diffractometer at the ILL. Data from these experiments have been used to determine solvent and hydrogen positions in crystals of tetragonal lysozyme (Nobuo Nimura, JAERI), concanavalin A (John Helliwell, Manchester) and coenzyme cob(II)alamin (Paul Langan, LANL). LADI uses a cold quasi-Laue beam in combination with a large neutron image plate (IP) detector in order to improve data collection efficiency from protein crystals. Nobuo Nimura explained the newly developed neutron IP technology used on LADI and on diffractometer BIX 1 at JAERI (Japan). Neutron IPs with low g sensitivity will be used on instrument BIX 2 proposed for a high flux thermal beam. Increasing the neutron beam flux by using polychromatic neutrons results in a corresponding increase in the background mainly produced by incoherent scattering from hydrogen. BIX 2 will therefore use a monochromatic beam. Comparisons of neutron and X-ray scattering density maps of myoglobin and vitamin B12r were used to show that hydrogen can be located in atomic resolution X-ray maps, but not at resolutions typical for most protein crystals. The power of neutrons for locating hydrogen even at resolutions below 2 Å was illustrated many times during the day. Neutron diffraction offers a greater relative scattering power for hydrogen and no decrease in form factor with scattering angle.

In the absence of Benno Schoenborn, Paul Langan presented his paper on the design of a structural biology station at LANL. With spallation neutrons and their time-dependent wavelength structure, diffraction data are collected as wavelength resolved spectra. This allows most of the neutron beam flux to be used with adequate spatial and temporal resolution and without the poor peak-to-background associated with the conventional Laue method. To maximize flux, a partially coupled moderator has been designed and built. These features, in combination with a cylindrical 120 x 20 position sensitive detector, are projected to improve data collection efficiency compared to the protein crystallography station at BNL many fold.

Bob von Dreele used recent X-ray data collected from Insulin and Met-Myoglobin at the NSLS synchrotron at BNL to answer affirmatively the question, "Protein Structures by Powder Diffraction?" This technique has promising applications in neutron diffraction, in the screening of heavy atom derivatives and in following changes in protein conformation, packing and solvent as a function of various parameters. With a large emphasis on membrane bound proteins at this years ACA meeting, Peter Timmins (ILL) reported on the use of low resolution (~12 Å) neutron diffraction to locate detergent in three different crystal forms of porins was very topical. As with low-resolution crystallography, phasing is often a problem with studies of biological films using reflectometry. Chuck Majkrzak (NIST) explained how phasing can be achieved using a buried reference layer. D. Clemens (PSI) described instruments at SINQ that depend on supermirror coated guides to maximize neutron flux.

There were two excellent presentations of studies on fibrous systems. Because partially ordered systems cannot benefit from conventional Laue methods, improvements in data collection efficiency will come only from using larger detectors at existing sources or time-of-flight methods with instruments at spallation sources. Magdalena Ivanova (Florida State University) described how a model was constructed for the coat protein of filamentous bacteriophage M13, on the basis of neutron diffraction data collected from magnetically oriented gels with specifically deuterated residues at the HFBR at BNL. Trevor Forsyth (Keele) presented neutron fiber diffraction studies of DNA hydration. Data collection efficiency in these studies will be greatly improved by a large array of microstrip detectors being developed for D19 at the ILL, which Trevor hopes to help commission over the next few years.

During a break between sessions a meeting of experts was held to discuss options for the design of the neutron crystallography station that will be built at the ORNL HFIR. This meeting was held as part of the planning process to establish a Center for Structural Molecular Biology at ORNL that will make existing resources in neutron sciences, mass spectrometry and computational biology available to the biological community.

The closing round table session chaired by Jim Sacchettini (Texas A&M) and aided by Gerry Bunick (ORNL) and Paul Langan (LANL) was dominated by discussion on how to coordinate efforts for software development to deal with the expected increase in data from new and existing instruments. In order to avoid duplicating efforts, instrument scientists present agreed to explore areas of common interest. It was also agreed to set up a process of consultation with the existing and potential structural biology community with a view to anticipating their needs. Other topics discussed included the advantages of medium resolution neutron studies over high-resolution X-ray studies for locating hydrogen and the need for a tandem effort in growing larger crystals and