ALSNews is a biweekly electronic newsletter to keep users and other interested parties informed about developments at the Advanced Light Source, a national user facility located at Lawrence Berkeley National Laboratory, University of California. To be placed on the mailing list, send your name and complete internet address to ALSNews@lbl.gov. We welcome suggestions for topics and content.

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ALSNews           Vol. 87           October 1, 1997

Table of Contents


    1. HIGH-RESOLUTION X-RAY IMAGES OF MANGANESE-EATING MICROBES
    2. USERS' MEETING OCTOBER 13-14
    3. WE'D STILL LIKE TO HEAR FROM YOU
    4. OPERATIONS UPDATE

1. HIGH-RESOLUTION X-RAY IMAGES OF MANGANESE-EATING MICROBES
(contacts: tonner@csd.uwm.edu, w_meyer-ilse@lbl.gov)

Cleaning up the environment is a monumental task, now consuming many billions of dollars annually. A new field of study, molecular environmental science, is emerging to contribute to effective waste remediation by investigating the routes contaminants take to their final destinations in the environment. These routes include formation of new compounds via interaction with their surroundings, transport through soils and groundwater, uptake in plant and animal life, and possible immobilization in benign forms. Bacteria, it turns out, are potentially key agents with the ability to purify contaminated soils and water supplies. Using the XM-1 microscope at Beamline 6.1.2, researchers have produced high-resolution images of bacteria and mineral particles in water, a key step toward investigating such bacterial bioremediation.

Most of the key reactions for bioremediation take place in water, so the solubility of contaminants makes all the difference in their transport through the environment. Various bacteria can oxidize (remove electrons from) or reduce (add electrons to) metal atoms, such as iron and manganese. When iron and manganese dissolved in water are oxidized, they form insoluble oxide compounds such as goethite (FeOOH) and manganite (MnOOH), resulting in solid mineral deposits. This process (when facilitated by bacteria) is called biomineralization. Conversely, reduction of the metals already in mineral particles causes them to dissolve into the surrounding water.

Biomineralization shows promise for environmental cleanup in at least two ways. If bacteria could directly mineralize contaminants such as plutonium, uranium, and chromium, this bacterial digestion would immobilize them as insoluble sediment. Alternatively, biomineralized deposits of other metals (e.g., manganese) could attract contaminants, which would then form insoluble compounds on the surfaces of the mineral deposits. Learning which, if either, of these mechanisms is a potential route to bioremediation involves analyzing the chemical reactions, their products, and where they occur relative to the bacteria and the particle surfaces.

X-ray absorption microscopy provides a suitably sensitive tool for imaging the key players in biomineralization. It easily resolves manganite needles (about 1 micron long and 0.1 micron wide) and the bacteria that metabolize manganese (similar lengths but a little more rotund). Since the manganese and carbon atoms in the bacteria absorb x rays at different wavelengths, the mineral particles and microbes are easily distinguished by making separate images at the appropriate wavelengths.

One challenge being addressed is the influence of water on x-ray measurements. Since water absorbs x rays, specially designed sample holders have been designed to minimize the distance the x rays must travel through water. Water also influences the positions and shapes of x-ray absorption peaks, so future absorption measurements to identify chemical species will require detailed examination of model compounds in wet cells to establish their characteristic spectral signatures.

This work was conducted by B.P. Tonner (principal investigator) and K. Nealson (University of Wisconsin-Milwaukee), and W. Meyer-Ilse and John Brown (Berkeley Lab's Center for X-Ray Optics). Funding: Office of Biological and Environmental Research of the U.S. Department of Energy, Laboratory for Surface Studies and Center for Great Lakes Studies (University of Wisconsin-Milwaukee), and Office of Basic Energy Sciences of the U.S. Department of Energy.

2. USERS' MEETING OCTOBER 13-14
(contact: alsuser@lbl.gov)

The ALS Users' Association Annual Meeting is coming up on October 13-14, with workshops on October 15-16 (a list appeared in ALSNews Vol. 85, September 3, 1997). If you are interested in attending the meeting but have not received a mailing about it, you can still receive information by fax. Send email to alsuser@lbl.gov with "please fax Users' Meeting information" in the subject line and your fax number in the body of the message.

The exact program of speakers is still being finalized, but the sessions will be as follows:

Monday, October 13, 1997

08:30-10:00  Welcome and Washington Update
10:30-12:00  ALS Update
12:00-14:00  Box Lunch, Vendor Exhibit, ALS Visit, Special Tours, 
             Set Up Posters
14:00-15:40  Spectromicroscopy - Materials Science
16:00-17:40  Atomic, Molecular, and Chemical Dynamics Science
19:00        Banquet

Tuesday, October 14, 1997

08:30-09:50  Biological Materials
10:20-12:00  Novel Properties of ALS Radiation, Including Coherence and 
             Short Time Structure; New Instrumentation
12:00-14:00  Box Lunch, Vendor Exhibit, ALS Visit, Poster Session
14:00-TBA    Recent Results from the ALS

3. WE'D STILL LIKE TO HEAR FROM YOU
(contact: alsnews@lbl.gov)

Thanks to all of you who have replied to the reader survey in our last issue (September 17) for your opinions, suggestions, and appreciations. If you have not yet filled out the survey, we would still like to hear what you have to say. The survey will be available on the Web until October 6, when we will tabulate the results. You can also send email or fax replies until then. We appreciate hearing from you!

4. OPERATIONS UPDATE
(contact: rmmiller@lbl.gov)

Beam reliability for the last four weeks was 91.9% overall and 90.8% for user shifts. All outages were of short duration.

Operations Summary for October 1 - October 20

Oct 01, 00:00-08:00           1.5-GeV/400-mA/287-bunch user operations
                              (no special operations requested)
Oct 01, 08:00- Oct 06, 07:15  1.5-GeV/400-mA/287-bunch user operations
Oct 06, 07:30-24:00           Maintenance & startup
Oct 07, 00:00-24:00           Accelerator physics
Oct 08, 00:00-08:00           User scrubbing & special operations
Oct 08, 08:00- Oct 13, 07:15  1.9-GeV/400-mA/287-bunch user operations
Oct 13, 07:30-24:00           Maintenance & startup
Oct 14, 00:00-24:00           Accelerator physics
Oct 15, 00:00-08:00           User scrubbing & special operations
Oct 15, 08:00- Oct 20, 07:15  1.9-GeV/400-mA/287-bunch user operations

** MAJOR TASKS ACCOMPLISHED IN MAINTENANCE SHUTDOWN **
The current ALS operating schedule has one-day maintenance shutdowns each week, with one each month extended to two days. These maintenance periods help shorten our longer shutdowns (one or two per year in recent years) for major installations. During the September 22-23 shutdown, in addition to the usual busy pace of work, the mechanical technicians (ALS) and riggers (Berkeley Lab Facilities) put in extra effort to accomplish three large tasks. They

- Installed new concrete shielding blocks in Sector 4, making room for Beamline 4.0 components to be installed in the April-May 1998 shutdown;

- Modified the M1 mirror and mask assembly at Beamline 5.0 to improve its cooling; and

- Installed a front-end stand for Beamline 10.0's first gate valve.

Thanks and kudos to all involved in these efforts!