NEWS OF THE WEEK NATIONAL SECURITY
BEES ON PATROL Studies find bees are potential chemical, biological agent detectors
F
OR THE PAST THREE YEARS,
the Pentagon has been testing honeybees as detectors for explosives in bombs and biological agents in ambient air. If the promising test results hold, bees could be used as border security sentries and as combatants against agricultural bioterrorism. In work funded by the Defense Advanced Research Projects Agency, the University of Montana (UM), Missoula, and its many partners are "exploring the ability of bees to look for biological agents," explains UM entomologist Jerry J. Bromenshenk. Bromenshenk has trained bees to sniff out parts-per-billion or lower concentrations of explosive
residues such as 2,4-dinitrotoluene and chemical weapons instead of nectar. InMay 1998, C&EN reported on the bomb residue and chemical weapons research whose aim was "to train bees to find things by their chemical signatures," Bromenshenk says. Current UM research, however, is looking "at the electrostatic charges on bees" to see how well the insects can scour the air for biological agents such as anthrax spores. The work exploits untrained bees asflyingelectrostatic dust mops to detect biological agents over wide areas. In these studies, bacterial spores, for example, that have been ad-
SCIENCE
ELUSIVE BINARY NITRIDE PREPARED Na 3 N synthesized from its elements by low-temperature technique
S
ODIUM NITRIDE, A COM-
pound that some scientists claimed could not exist, has been prepared and characterized by chemists at the Max Planck Institute for Solid-State Research, Stuttgart, Germany Research chemist Dieter Fischer and chemistry professor Martin Jansen prepared amorphous solid Na3N by generating atomic beams of sodium and nitrogen separately in a vacuum chamber and codepositing the atoms onto a liquid-nitrogencooled sapphire substrate [Angew. Chem. Int. Ed., 41,1755 (2002)}. The Na3N changes to a crysHTTP://PUBS.ACS.ORG/CEN
talline form when heated to room temperature and decomposes into its elements at 87 °C. Analysis of X-ray powder diffraction patterns of the crystals reveals that the compound has a lattice structure of the type known as antiRe0 3 in which octahedra are connected at all six corners to adjacent octahedra to form a threedimensional network. Six sodium cations are located at the corners and one nitrogen atom is in the center of each octahedron. "Sodium nitride is an extremely labile compound. It is impossible to prepare it using conventional solid-state reac-
sorbed on the bees' back hairs are washed off and are eventually quantified and identified through culturing or polymerase chain reaction analysis. The ongoing explosives detection research, however, uses trained bees and is being conducted by Sandia National Laboratories, a UM partner. Independent verification of Sandia's research was carried out last summer at Southwest Research Institute, San Antonio, also a UM partner. Trained MULTITASKING In addition to colonies of bees were producing honey, these bees successfully able to detect chemicals emitted by detect bomb explo- land mines (foreground). sives, making bees ~~ possible sentinels against terrorists at security checkpoints such as truck stops.-LOIS EMBER
tions," Jansen tells C&EN. "Our approach can be used to carry out all solid-state reactions at unprecedented low temperatures." The only other well-characterized alkali-metal nitride is Li3N, which forms spontaneously from lithium and nitrogen at room temperature. According to Rainer Niewa, a research chemist at the Max Planck Institute for Chemical Physics of Solids, Dresden, it might be feasible to use Fischer Jansen and Janseris synthetic technique to prepare the binary nitrides of potassium, rubidium, and cesium. "With the development of new synthetic routes, further new (especially metastable) compounds of nitrogen might be expected in the near future," Rainer suggests in the same issue of Angwandte Chemie (page 1701). "Such new compounds will inevitably have surprising structure chemistry and physical properties and, thus, provide new impulses in solid-state chemistry"— MICHAEL FREEMANTLE
C & E N / MAY 2 0 , 2002
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