NMR Finds Foul Fuels

Drought-stressed trees emit an ultrasonic yelp that may at- tract bark- and wood-boring insects. Robert Haack of the. U.S. Department of Agriculture F...
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Society for Analytical Chemists of Pittsburgh Starter Grants Awarded T h e Society for Analytical Chemists of Pittsburgh has awarded $10,000 starter grants to Werner Kuhr, University of California a t Riverside, and to Jennifer Brodbelt-Lustig, University of Texas at Austin. T h e grants are designed to encourage high-quality innovative research by young pro­ fessors in the field. Kuhr received his P h . D . under the direction of R. M a r k Wightman a t Indiana University and carried out postdoc­ toral work at Iowa S t a t e University with Edward Yeung. He joined the Riverside faculty in 1988 and will use the grant to develop capillary zone electrophoresis to sample transient neurochemical events in the brain. Brodbelt-Lustig earned her Ph.D. from P u r d u e Univer­ sity under the joint direction of R. G r a h a m Cooks a n d Peter Kissinger. She is currently a postdoctoral s t u d e n t with Michael Bowers at the University of California, Santa Barbara, and will join the University of Texas staff in Sep­ tember. Brodbelt-Lustig's research will focus on ion-mole­ cule reactions in M S .

NMR Finds Foul Fuels Proton N M R spectra may provide a rapid method for pre­ dicting the thermal stability of hydrocarbon jet fuels. J o h n Russell and Brent Bailey, researchers with t h e Southwest Research Institute in San Antonio, T X , are developing this thermal stability analysis to screen fuels for the National Aerospace Plane (NASP), the high-tech aircraft being de­ veloped by the United States for flight at Mach 7 to 10. Fuel aboard the N A S P is slated to double as a coolant, circulating through heat exchangers in the aircraft's lead­ ing edges and engines. As it carries heat away from t h e fuselage and engine, fuel t e m p e r a t u r e s could approach 500 °C. If the fuel decomposes prior to combustion, the re­ sulting gums and soot could foul heat exchangers, plug fil­ ters, and clog fuel injectors. According to Russell, fingerprint regions of the N M R spectrum can be matched to a fuel's deposit-forming ten­ dencies at high temperatures. For instance, N M R peaks for aromatic hydrocarbons indicate a lower fuel stability.

The Sound of a Thirsty Tree Drought-stressed trees emit an ultrasonic yelp t h a t may at­ tract bark- and wood-boring insects. Robert Haack of t h e U.S. D e p a r t m e n t of Agriculture Forest Service in East Lansing, MI, has characterized the duration and strength of these signals using sound transducers attached t o trees. He is now generating these same sounds and testing insect response to the ultrasonic pulses. T h e noise, first reported in 1983, occurs when water col­ umns running up the tree snap apart. Because these col­ umns are under tremendous tension, breaking the column generates a pulse with a frequency of > 20 kHz. T h e ultra­ sonic sound has been recorded in hardwoods, such as apple and red maple; conifers, including Scotch pine and eastern hemlock; and even in corn. Haack, speaking at the Acoustical Society of America's meeting in Syracuse, NY, also pointed out t h a t droughtstricken trees emit different volatile chemicals and have higher temperatures t h a n normal. These factors may also aid insects looking for a drought-weakened tree. 770 A · ANALYTICAL CHEMISTRY, VOL. 6 1 , NO. 13, JULY 1, 1989

Killer Bee Buzz Also speaking a t t h e Acoustical Society of America meet­ ing, Howard Kerr and M. E. Buchanan of B-Tec, Inc., Maryville, T N , reported t h a t sound signals can differenti­ ate flying E u r o p e a n bees from t h e more aggressive African­ ized or "killer" bees. Because of taxonomical differences, European honeybees emit an acoustic power peak in the 210-230-Hz range, whereas the Africanized bees produce a signature at 260280 Hz. T h e researchers found t h e signal difference after collecting time-averaged signals from bees in flight and using Fourier analysis to create power spectral density plots, which revealed the acoustic variation. B-Tec has applied for a p a t e n t based on t h e finding. T h e firm will use the sound difference to m a r k e t a field instru­ m e n t called "Buzz B u s t e r " for screening Africanized bees.

Chip off the Old Prism W h a t may be the world's smallest optical prism has been unveiled by physicists Robert Gallawa of t h e National In­ stitute of S t a n d a r d s and Technology laboratories in Boul­ der, CO, and Zongjian Sun, visiting scientist from Tongji University in Shanghai, China. Measuring less t h a n 125 μπι on a side, this microprism (shown next to a 125-μπι optical fiber) is barely visible to the naked eye.

According to Gallawa, the prism was carved from optical glass in a " b r u t e force approach" requiring approximately 16 h of constant grinding. Microprisms such as these could be used as measuring tools to determine the light propaga­ tion characteristics of fiber optics t h a t relate to the mater­ ial's ability to carry information. In addition, these prisms might someday find a role in miniaturized optical circuits. " I t was a demonstration t h a t has served its purpose," Gallawa explained. " I t is one of those things t h a t is moti­ vated by curiosity, and when finished you are amazed."

For Your Information T h e International U n i o n of P u r e and Applied Chemis­ try (IUPAC) Analytical Chemistry Division has formed a Committee on Environmental Analytical Chemistry. T h e committee's agenda ranges from problems in particle sampling to redox processes and eutrophication. For more information, contact Jacques Buffle, D e p a r t m e n t of Inor­ ganic, Analytical, and Applied Chemistry, Sciences II, 30 quai E. Ansermet, 1211 Genève 4, Switzerland.