Science Highlights 2005

Science highlights of research occuring at the APS.

How a Cellular "Spacecraft" Opens its Airlock
Researchers using a Structural Biology Center beamline at the APS have clarified the connection between the tiny hatchways that allow nutrients to pass into our cells and the steps by which they use a cell's energy to permit or deny materials entry into the interior of the cell from the outside world.
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Defect-Driven Magnetism in Mn-doped GaN
Semiconductors doped with magnetic elements are candidates as room-temperature magnetic semiconductors with potential use as new low-power-consumption electronics, non-volatile memories, and field-configurable logic devices. Research at the U.S. Department of Energy’s Advanced Photon Source is producing new and important information about Mn-doped GaN.
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Mapping One of Biology's Critical Light-sensing Structures
For plants, the ability to accurately sense light governs everything from seed germination, photosynthesis, and pigmentation to patterns of growth and flowering. Now scientists using beamline 32-ID-B the Advanced Photon Source have obtained a detailed map of one of biology's most important light detectors, a protein found in many species across life's plant, fungal, and bacterial kingdoms.
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Rare Insights About Permanent Magnets
Permanent magnetic materials play a major role in the conversion of mechanical-to-electrical energy in alternators and generators and are used in a myriad of other products and technologies. Researchers using the X-ray Operations and Research beamline 4-ID-D at Argonne National Laboratory’s Advanced Photon Source have found important new clues into ways to make those magnets longer-lasting and more powerful.
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Should Drugs Be Designed “On the Fly”? (Oct. 12)
The first close-up look at a pro-inflammatory signaling molecule involved in immune response in mammals suggests that researchers “should rethink what they are doing” in creating drugs based on a fruit-fly model.
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Phasing Out the Phase Problem in Interfacial Crystallography (Oct. 6)
Since the advent of dedicated synchrotron radiation facilities, the applications of x-ray diffraction and scattering for structure determination have expanded to include a broad range of materials, from proteins and interfaces to nanoparticles. However, the well-known “phase problem” of crystallography limits these applications.
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Cheaper Silicon Found Effective for Solar Cells
Researchers using Advanced Photon Source and Advanced Light Source beamlines have shown that inexpensive silicon has the potential to be used for photovoltaic devices, commonly known as solar cells. In a new approach—whose findings were published online in Nature Materials (August 14, 2005)—the researchers used nanodefect engineering to control transition metal contamination in order to produce impurity-rich, performance-enhanced multicrystalline silicon material.
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Characterizing Complex Metal-Cluster Proteins
An article on the application of nuclear resonance vibrational spectroscopy (NRVS) to the study of complex metal-cluster proteins is featured on the cover of Inorganic Chemistry 44(16) 5562 (2005). This work, which was carried out at X-ray Operations and Research beamline 3-ID, shows NRVS to be a promising tool for the investigation of metalloxide protein clusters that have, to date, resisted study with other techniques. These clusters are of great interest due to their potential use as molecular switches that might be used to regulate protein biosynthesis or enzyme stability.
Image: Copyright © 2005 American Chemical Society
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"Cookbook Recipes" Would Cure Disease with Nontoxic DNA Delivery Systems
Scientists studying the structure and interaction of negatively charged lipids and DNA molecules have created a “cookbook” for a class of nontoxic DNA delivery systems that will assist doctors and clinicians in the safe and effective delivery of genetic medicine.
Image: Copyright © 2005 by the National Academy of Sciences
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What's Music Got to do with X-ray Diffraction? (Aug. 2)
Harmonic analysis exists in both science and music and is in fact the basis of much science, including x-ray diffraction. The geometric quality of vibrations that make up music are harmonic in time. Similarly, the work of physics, such as at Argonne’s Advanced Photon Source, which examines the structure of life itself, is focused on what is harmonic in space. To learn more about harmony in music, see "Physics of the Blues" in the online version of Argonne's Explorer magazine.
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Revelations about the Center of the Earth (Jul. 21)
Seismologists have observed that the speed and direction of seismic waves in Earth’s lower mantle, between 400 and 1,800 miles below the surface, vary tremendously. New research carried out at the High Pressure Collaborative Access Team beamline at the APS may reveal why those seismic waves travel so inconsistently and may explain the complex seismic wave anomalies observed in the lowermost mantle.
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Nanoskins on Layered Manganites (Jul. 20)
Researchers from Argonne National Laboratory have successfully demonstrated that an insulating nanoskin (an ultrathin insulating, non-ferromagnetic tunnel barrier layer) in contact with a completely ferromagnetic metallic layer can be naturally created. Assembling a uniform layer five atoms thick (10 Å) and without defects is no mean feat. In their Nature Materials paper, the researchers note that situating a well-defined surface insulator atop a fully spin-polarized bulk demonstrates that two of the most demanding components of an ideal magnetic tunnel junction can self-assemble naturally.
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Molecular Ballet Unravels, Links Proteins so Cell Can Direct Own Movement (Jul. 11)
A protein called vinculin moves cylinder-like fingers to form a hand to which an arm extended by a protein partner called alpha-actinin can bind, according to a study carried out at the Structural Biology Center beamline 19-ID at the Advanced Photon Source. Without vinculin to reinforce its skeleton, a cell would move rapidly and randomly, making purposeful motion impossible. That means cells could not migrate properly in the developing embryo to take up their final positions, leaving the embryo to wither and die; yet the ability to move purposefully also helps individual cancer cells break away from a tumor and spread to other parts of the body, a process called metastasis. Therefore, discovering how cells direct their movements could help researchers better understand how embryos develop and how some cancers spread.
Figure credit: YaleGlobal Online © 2005 Yale Center for the Study of Globalization
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Lighter Filling in Earth’s Core (Jun. 23)
New experiments conducted at the Advanced Photon Source by a team from the Carnegie Institution suggest that the core of the Earth may contain more light elements than previously thought. The research is published in the June 24, 2005, issue of Science.
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Seventeenth-Century Islamic Brassmakers Were Far Ahead of European Peers (Jun. 24)
Manufacturers of brass astrolabes in 17th-century India were two centuries more advanced than their European peers, says a doctoral student at Lehigh University who just completed a four-year study of astrolabes. The astrolabes' alloy composition was measured by performing x-ray diffraction, x-ray fluorescence and x-ray radiography experiments on 40 astrolabes at the Advanced Photon Source at Argonne National Laboratory in Chicago.
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APS Aids UIC in Developing Drug for SARS (Jun. 08)

A prototype drug created by researchers at the University of Illinois at Chicago shows promise in slowing replication of the virus responsible for severe acute respiratory syndrome, or SARS.
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Researchers Uncover Structure of Key Protein Complex in Cells (Jun. 01)
Using brilliant x-ray beams from the Advanced Photon Source at the Structural GenomiX beamline (sector 31), scientists at Memorial Sloan-Kettering Cancer Center have uncovered the structure of a network of proteins that help regulate the life cycle of cells. Understanding the network's physical layout is an important step toward learning its precise function, and in finding ways to correct flaws in the system that could lead to cancer.
Graphic copyright © 2005 Elsevier B.V. All rights reserved.
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Major Advance Made on DNA Sructure (May 11)
Oregon State University researchers using the BioCARS facility at Argonne National Laboratory's Advanced Photon Source and a beamline at the Advanced Light Source (Lawrence Berkeley Laboratory) have made significant new advances in determining the structure of all possible DNA sequences – a discovery that in one sense takes up where Watson and Crick left off, after outlining in 1953 the double-helical structure of this biological blueprint for life.
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Zinc Deficiency Linked to Esophageal Cancer (Feb. 16)
Researchers at the National Cancer Institute (NCI), part of the National Institutes of Health, using x-ray fluorescence spectroscopy at X-ray Operations and Research beamline 2-BM at the U.S. Department of Energy's Advanced Photon Source have found that zinc deficiency in humans is associated with an increased risk of developing esophageal squamous cell carcinoma, an often-fatal form of esophageal cancer that has about 7,000 cases a year. Their results, appearing in the February 15, 2005, Journal of the National Cancer Institute, showed an inverse relationship between tissue zinc concentration and subsequent risk of esophageal squamous cell carcinoma.
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X-ray movies reveal insect flight, muscle motion (Feb. 07)
Watching flies fly may not seem like high-tech science, but for researchers using the Western Hemisphere's most brilliant X-rays, located at the Advanced Photon Source at the U.S. Department of Energy's Argonne National Laboratory, it not only helps explain how insects fly but also may someday aid in understanding human heart function.
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