"It lets us predict that all the glycine and serine pairs form loops," she notes. "It allows us to suggest that the randomness that nature incorporates in dragline silk will have to be duplicated in 'synthetic' genes to achieve materials with the same mechanical properties as silk." The vision that high-performance synthetic fibers can be synthesized from repetitive sequences of 30 amino acids may need revamping, she explains. In a commentary in the same issue of Science, David A. Tirrell, professor of polymer science and engineering at the University of Massachusetts, Amherst, notes: "Materials scientists are increasingly willing to turn to biology for lessons that might be transferred from natural to synthetic systems. A substantial step forward along this path has been taken by Jelinski and coworkers." Mairin Brennan
Panel praises NIST technology programs The importance of the National Institute of Standards & Technology (NIST) to U.S. industry is spelled out clearly in a study by the National Research Council (NRC). But attempts in Congress to revamp NIST's operations have raised concern that significant changes may be coming in NIST's role, with political maneuvering for short-term goals perhaps jeopardizing important research. The report by an NRC Board of Assessment is NRC's 37th annual assessment of NIST programs, evaluating their effectiveness and making recommendations for improvement. The overall assessment for 1995 is that NIST's programs are of very high quality and its research efforts are quite effective. The report makes two observations concerning potential changes stemming from Erom GOP GOP attempts attempts to to dismantle dismantle the the DeDepartment of Commerce, of which NIST is part. 'It is not possible for the nation to maintain government-certified standards, weights, and measures without the technical activities of the NIST laboratories," the report bluntly states. NIST is one of just a handful of organizations around the world with the scientific expertise and objectivity needed to develop scientific standards and innovative technology, the study adds. The board also stresses that the added duties given NIST over the past few
years have actually improved its operations—and have not detracted from its traditional functions. In particular, the NRC panel cites a synergy between NIST labs and the Advanced Technology Program (ATP), "which has stimulated appropriate new research directions in the laboratories and helped identify emerging needs for standards and measurement services." Congressional Republicans have singled out ATP as an example of "corporate welfare" and have specifically deleted it from NIST's 1996 appropriations bill. The program's purpose is to fund high-risk research at innovative companies that otherwise might not try to translate their ideas into successful products or processes. Loss of the program would leave scores of smaller research firms without funds. NIST's future is still swinging in the congressional winds. But the major effort to kill the Commerce Department has stalled, halting at least for the time being the changes sought at NIST and other Commerce agencies. David Hanson
Weak hydrogen bonding between water molecules creates clusters of various sizes, including this pentamer structure that forms a slightly puckered ring.
have not yet developed accurate models of its behavior." "For as important as water is in natural chemistry," Cruzan adds, "we still don't understand much about it." Chemists have long studied water's cluster-forming nature, where molecules group together by weak hydrogen bonding. Two decades ago, researchers at the University of Rochester began studying the microwave spectrum of the water dimer. Larger clusters are more difficult to Researchers at the University of Cali- study, Saykally says. Chemical vibrafornia, Berkeley, have characterized the tions of the water molecules themselves structures of water tetramers and pen- overpower fainter, but more structurally tamers—the largest water clusters yet telling, hydrogen bond vibrations. "The pentamer and tetramer have been obobserved in detail. Chemistry professor Richard J. Say- served before in some very elegant speckally, graduate students Jeff D. Cruzan troscopic experiments, but still only as and Kun Liu, and coworkers confirmed broad blobs." with vibration-rotation tunneling [VRT] Saykally's lab specializes in far-infrared laser spectroscopy what theorists have laser VRT spectroscopy, the far-IR being predicted; the tetramer has a quasiplanar the vibrational frequency range of hydrocyclic shape, its free hydrogens oriented gen bonds. With VRT spectroscopy, scienalternately above and below the ring, tists can pinpoint all of the hydrogen whereas the pentamer's structure is a bonds' gyrations—rotations, vibrations, slightly slightly puckered puckered pentagon pentagon [Science, 271, and quantum mechanical tunneling. 59 and 62 (1996)]. A few years ago, the group published The Berkeley team's aims are twofold detailed studies of the water trimer [Sciin studying water, Saykally says: to char- ence, 257,1937 (1992)]. The tetramer and acterize the nature of interactions among pentamer discoveries are now sure to be water molecules in great detail, and to followed by hexamer, heptamer, and characterize the quantum mechanical even larger clusters, Saykally says. motions of hydrogen-bonding networks. "This is clearly the opening salvo in A thorough understanding of the moving on to much larger clusters that way water molecules clump and orga- will be intimately related to the strucnize is crucial in studying solvation ture of liquid water," says Geoffrey A. and biological systems, the scientists Blake, professor of cosmochemistry at say. "Most of biochemistry occurs in California Institute of Technology. liquid water," Liu explains. "Scientists Elizabeth Wilson
Water tetramers and pentamers observed
JANUARY 8,1996 C&EN
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