Detecting the magnetic force of protons.Of the more than 100,000 different proteins known to exist in the human body, most remain poorly characterized. Using crystallographic crys·tal·log·ra·phy n. The science of crystal structure and phenomena. crys  tal·log and other techniques, scientists so far have deduced the structures of only a few hundred of these giant molecules. As an important step toward developing a technique for obtaining images showing the three-dimensional atomic arrangement of individual molecules in their natural settings, researchers have now demonstrated that microscopic devices designed to sense minute magnetic forces can be used to detect nuclear magnetic resonance nuclear magnetic resonance: see magnetic resonance. nuclear magnetic resonance (NMR) Selective absorption of very high-frequency radio waves by certain atomic nuclei subjected to a strong stationary magnetic field. . Although this achievement falls short of detecting individual protons or nuclei in molecules, it represents a significant improvement in sensitivity and spatial resolution (Data West Research Agency definition: see GIS glossary.) A measure of the accuracy or detail of a graphic display, expressed as dots per inch, pixels per line, lines per millimeter, etc. It is a measure of how fine an image is, usually expressed in dots per inch (dpi). over that of conventional magnetic resonance imaging magnetic resonance imaging (MRI), noninvasive diagnostic technique that uses nuclear magnetic resonance to produce cross-sectional images of organs and other internal body structures. . Daniel Rugar and his coworkers at the IBM (International Business Machines Corporation, Armonk, NY, www.ibm.com) The world's largest computer company. IBM's product lines include the S/390 mainframes (zSeries), AS/400 midrange business systems (iSeries), RS/6000 workstations and servers (pSeries), Intel-based servers (xSeries) Almaden Research Center The IBM Almaden Research Center, located near San Jose, California, is one of IBM's largest research centers, specializing in both basic research in material science and applied research in computer storage, where many refinements and improvements were made in hard disc drive in San Jose, Calif., report their results in the June 10 SCIENCE. The notion of using nuclear magnetic resonance for imaging individual molecules originated with physicist John A. Sidles of the orthopedics department at the University of Washington School of Medicine The University of Washington School of Medicine (UWSOM) is a public medical school located in Seattle, Washington. It is a graduate school affiliated with the University of Washington, and is the only medical school in the states of Washington, Wyoming, Alaska, and Idaho. in Seattle (SN: 3/7/92, p.150). To demonstrate the idea's feasibility, Rugar and his colleagues subsequently adapted the technology used to measure tiny variations in magnetic forces across a surface to detect a magnetic resonance magnetic resonance, in physics and chemistry, phenomenon produced by simultaneously applying a steady magnetic field and electromagnetic radiation (usually radio waves) to a sample of atoms and then adjusting the frequency of the radiation and the strength of the effect involving the spins of electrons (SN: 3/27/93, p.199). Last year, Rugar and Othmar Zuger used their "magnetic resonance force microscope" to measure electron spins and produce images of tiny organic crystals. In the latest development, the researchers have refined their apparatus to pick up the much smaller signals from atomic nuclei. The key element responsible for achieving this high sensitivity is a microscopic sliver of silicon nitride, which vibrates like a miniature diving board (see image). Interactions between protons in a grain of ammonium nitrate, the magnetic field of a nearby iron particle, and radio waves cause the sliver to vibrate, creating a detectable signal. [CHART OMITTED] "The results ... demonstrate that [nuclear magnetic resonance] force detection can achieve remarkable sensitivity and spatial resolution," the researchers conclude. "Further advances are expected as progress is made toward more sensitive cantilevers, higher [magnetic] field gradients, and lower temperatures." "It's a technology that works better the smaller you make it," Sidles notes. |
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