the body responds to dietary adjustments. Working with 5-microliter samples of serum, Dr. Halpern adds ethanol to precipitate proteins which are removed by centrifugation. He esterifies fatty acids and free amino acids in the supernatant liquid with ethanol, and then adds trimethylacetaldehyde to convert the amino acids to their SchifFs bases. Components of this mixture are separated by gas chromatography and identified in the mass spectrometer. The entire quantitative analysis takes less than 15 minutes, he says. The Stanford workers use a Finnigan Instruments mass spectrometer which is designed around a quadrupole mass filter instead of a magnetic field. The main advantage of quadrupole, Dr. Halpern points out, is that it is well suited to quickly respond to computer control of the mass analyzer. Moreover, he adds, the data acquired by the instrument are automatically normalized and printed out or plotted on a mass vs. intensity scale, "Consequently, someone like myself who is not a mass spectroscopist by training can read and evaluate the data much as he would an IR or UV spectroscopy profile," he notes.
PESTICIDES:
Action from USDA Several more pieces in the puzzle over federal action and jurisdictional questions on pesticides fell into place last week, but the puzzle was by no means complete. It was also clouded with conflict-of-interest charges involving pesticide consultants to both the Government and Shell Chemical Co. Caught between reports critical of his department's activities, Agriculture Secretary Clifford M. Hardin said he is placing "greater emphasis" on registering new pesticides and reviewing those already registered. Under Agriculture's authority to regulate pesticides moving in interstate commerce and a new directive, USDA will now give "particular consideration" to how long and under what conditions a pesticide persists in the environment, whether it's likely to move out of the area of use, what adverse effects may result from degradation products, and, significantly, whether a pesticide is needed to prevent or control human disease "for which no alternative is available." Much of Agriculture's action also stems from a House Committee on Government Operations report detailing Agriculture's "deficiencies" in administering the Federal Insecticide, Fungicide, and Rodenticide Act ( F I F R A ) . Based on hearings last
THE CHEMICAL WORLD THIS WEEK
NOISE:
Silencing the Jets
Spraying pesticides A check on persistence May and June and an exhaustive subcommittee investigation, the report has such findings as: • USDA's Pesticides Regulation Division "failed almost completely" u p to mid-1967 to enforce FIFRA provisions protecting the public, but has made "significant improvements" since then. • USDA approved "numerous" pesticides for registration over HEW's objections, which number more than 1600 during the five-year period ending June 30, 1969. • "Serious conflict-of-interest questions" in the Agricultural Research Service's appointment of consultants who either worked for or were consulting for Shell Chemical. Specifically named and with charges against them documented in the report are Dr. T. Roy Hansberry of Shell who served on a task force examining criteria used by PRD in determining approval of pesticide registrations and Dr. Mitchell R. Zavon, "a medical consultant to Shell Chemical [who] served simultaneously as a consultant to the Pesticides Regulation Division." Also named is John S. Leary, Jr., a former PRD chief staff officer for pharmacology who subsequently resigned in December 1966 to join Shell. To correct the faults the House committee finds in the report it makes such recommendations as: • Reviewing registrations bearing "inadequate, misleading, contradictory, or confusing labeling," approved without resolving safety questions raised by HEW, making "unjustified effectiveness claims," or whose approved uses are "likely to result in adulteration or contamination of food." • Avoiding conflicts of interest.
Jet engine whine—a noise familiar to travelers and airport buffs—is an increasingly irritating noise to many. Attempts to reduce the noise by working on the fan-jet engine itself have been difficult, expensive, and not very successful. To Dr. Gerhard Reethof, Alcoa professor of mechanical engineering at Pennsylvania State University, this was reason enough to explore an unconventional approach using the engine's flame. Acoustic cancellation is the effect Dr. Reethof is trying for. If a pure tone sound can be generated in a jet engine's hot exhaust gases and pitched exactly out of phase with fan-blade noise, the two might cancel each other out. Engine whine results from blade-onair noise, which, Dr. Reethof says, seems to be inherent in the fan-jet principle. A fan-jet engine contains several sets of fixed and rotating blades. The fixed blades, stators, set up the air for the rotating blades to contact. Typically there are 53 blades on each rotor, turning at 3500 r.p.m., and one or two fan rotors in a single jet engine. Rotor blades contacting the air cause the engine noise. Since the noise produced is a pure tone, it is theoretically susceptible to cancellation by another equal but opposite pure tone. Working in an anechoic chamber, Dr. Reethof and graduate student Mike Oslac are trying to produce that equal but opposite pure tone in a flame simulating the exhaust flame of a jet engine. The high-velocity flame they are using is 5 inches long and less than 1 inch wide. The first step in producing a tone is to electrify the flame by applying an oscillating voltage directly across it. The flame is then seeded with ions in a fine misty spray. When the ions collide with the gas molecules in the flame, a sound results. It is a pure tone having the same intensity in all directions around the anechoic chamber. Dr. Reethof, formerly a manager of the flight propulsion division of General Electric, uses potassium chloride solution sprayed onto the flame as the source of ions. For electrifying the flame, one electrode is mounted in the flame while the copper tube out of which the flame shoots functions as the other. They provide 600 volts, suitable for the experiments but much lower than would be required in a jet engine. So far, experiments are still in the simulation phase in the chamber. The flame simulates one tone, while a loudspeaker simulates engine whine. NOV. 24, 1969 C&EN
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