hands-on approach in the freshman design course (
Beamline boasts big returns
Researchers at the Synchrotron Radiation Center (SRC) developed a source of soft X-rays that could spawn a new research area in the damage and repair of cell nuclei. As reported in the April 24 issue of the journal Science, geneticists used the SRC's soft X-ray source to irradiate one-micron-wide stripes of cell nuclei through a mask. "Typically a half dozen stripes fit into a nucleus," says Professor Max Lagally. "The repair of DNA damage can now be studied with one-micron lateral resolution."
Radiation causes damage to DNA double-strands which the nucleus is sometimes able to repair. To observe sites within damaged cells, Lagally, SRC researcher Jim MacKay, and Professors Mike Gould (oncology,) Paul deLuca (medical physics), Rockwell Mackie (medical physics) and Ben Nelms used soft X-rays and microfabricated irradiation masks to induce DNA damage in discrete subnuclear regions of irradiated cells.
Medical School Assistant Professor of Medical Genetics John Petrini, working with researchers Nelms and Rick Maser, used the technique to show special repair proteins at work, moving immediately from their home bases to remote gene damage sites. The new observation method opens up a wide range of possible experiments in cell damage and repair.
Creating a new class of substrates
A team of college faculty is working to create new classes of substrates for the growth of high-quality semiconductor thin films. The group includes Professors Thomas Kuech, chemical engineering, Max Lagally, physics and materials science and engineering (MS&E), Richard Matyi (MS&E), Susan Babcock (MS&E), Roxann Engelstad, mechanical engineering (ME) and Edward Lovell (ME). Novel substrates on which defect-free materials can be grown are crucial to a variety of new technologies, including the manufacture of high-quality GaN-based materials for laser and light-emitting diode applications and high-power, high-temperature electronics. The group is researching two parallel, complementary approaches. The first uses a low viscosity boro-silicate glass layer to mechanically decouple a continuous template layer and the growing film from a necessary, but ordinarily (i.e., in conventional substrates) constraining handle wafer.
In the second approach, the growing material is seeded on poorer quality conventional material to establish the single crystal, and then laterally grown over glass, which again removes the mechanical constraints that normally lead to defect incorporation in the film. The group is funded as a Multidisciplinary Research Program of the University Research Initiative (MURI) through the Office of Naval Research.
Eric E. Hellstrom, Chair
276 Materials Science and Engineering Building
1509 University Avenue
Madison, WI 53706-1595
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Date last modified: 01-Oct-1998
Date created: 1-Oct-1998
1998 Annual Report Contents