RATES

Churchill's distinction between a process rale and a rate-of-change clarifies an ambiguous situation replete with misunderstanding and loose usage. At best, uneasiness and, at worst, errors result from the ambiguity. The rate of reaction is considered here in the above context. Examples are given of cases where both process rates and rates-of-change occur simultaneously and non-identically. In such cases Churchill's distinction is crucial.     

SOME MOLECULAR EFFECTS IN DRAG REDUCTION: A SUMMARY†

Dilute solutions of high molecular weight polymers have drawn a great deal of interest in recent years because of their drag reducing characteristics. It is well-known now that a substantial reduction in turbulent frictional drag can be achieved with a very small amount of polymeric additives, usually only a few parts per million by weight (ppmw) in concentration. This unique phenomenon has offered a new dimension in the design development of new marine systems for higher speed, longer range, larger payload as well as possibly quieter machinery. Although the discovery of this turbulent drag reduction phenomenon may be traced back to Toms¹ and Mysels² in the 1940's, the U.S. Navy's exploration of the turbulent drag reduction effect did not begin until the pioneering effort of Hoyt and Fabula in the 1960's. ³ During a period of several years in the early 19707apos;s, an interdisciplinary group at the Naval Research Laboratory undertook an intensive basic research effort to study the effects of polymer molecular structure on turbulent drag reduction. Model compounds were synthesized in the laboratory, and their drag reducing properties characterized. Polymers including polyacrylamide and its derivatives, polyacrylic acid, poiyphosphate and association colloids have been investigated. In this report, an attempt is made to highlight some of the results from that program in a brief summary form.     

CYBERNETICS,TELEOLOGY, AND SCIENCE

Cybernetics has evolved far beyond the problems of servomechanics and simple models of purposive behavior into a substantial body of theory with potential for resolving long-standing controversies surrounding the role of teteological concepts and reductionism in scientific explanation. The diverse research contributing to modem cybernetics views natural adaptation, goal-directed behavior, and conscious purpose as varying expressions of circular causal, recursive, and system/environment relationships along a continuum of organized complexity. This mode of analysis suggests that hierarchy in the sciences springs from a hierarchy of causal circuits in the structure of ideological phenomena, for which the dual, part/whole nature at any particular level forces a bifurcation of discourse into distinct “logical types” according to the observer's focus. The cybernetic paradigm may thus provide connecting tissue by which the full spectrum of explanation, from physicochemical to teleological, is joined in a coherent scientific framework constituting “reduction in principle” of living systems, even while truly meaningful translation of one science into another is precluded by the disparate logics of their subject matter.     

ELECTROGENERATIVE OXIDATION OF ETHANOL TO ACETALDEHYDE

Ethanol enriched vapor streams from twenty-five volume percent ethanol-water mixtures can be selectively oxidized with porous platinum electrodes and sulfuric acid electrolyte in the elec-trogeneratice mode to give acetaldehyde. Acetaldehyde yield from ethanol depends on potential and feed rate of ethanol vapor in the carrier gas stream. Control of conversions of ethanol to acetaldehyde in the range of 3 to more than 60 percent in a single stage is demonstrated. It is shown that at moderate flow rates for selective conversion there is a preferred potential range at which to operate the electrogenerative reactor.     

Meter as Mechanism: A Neural Network Model that Learns Metrical Patterns

One kind of prosodic structure that apparently underlies both music and some examples of speech production is meter. Yet detailed measurements of the timing of both music and speech show that the nested periodicities that define metrical structure can be quite noisy in time. What kind of system could produce or perceive such variable metrical timing patterns? And what would it take to be able to store and reproduce particular metrical patterns from long-term memory? We have developed a network of coupled oscillators that both produces and perceives patterns of pulses that conform to particular meters. In addition, beginning with an initial state with no biases, it can learn to prefer the particular meter that it has been previously exposed to.     

VELOCITY PROFILES OF FLUID/PARTICULATE MIXTURES IN PIPE FLOW USING MRI

Magnetic resonance imaging (MRI) techniques have been utilized to experimentally measure velocity profiles and apparent Theological properties of fluid/paniculate mixtures as functions of flow rate, particle loading, and particle size. The experimental velocity profiles were described by apower law model for these systems. A 3% aqueous sodium alginic acid solution was used to form two particle sizes of 2.5 mm and 5.0mm in diameter. The spheres were suspended in a 0.5% carboxymethyl cellulose solution at loadings ofO, 10, 20, and 30% by weight. The average fluid velocity ranged from 2–35 cm/s. The flow behavior index decreased as flow rate, particle loading or particles size increase. Cumulative residence time curves were evaluated based on this modeling procedure. Results of this research have direct application to aseptic processing of fluid/particulate mixtures.     

Heat Gelation of Oil-in-Water Emulsions Stabilized by Whey Protein

The conditions under which a high volume fraction of oil can be trapped in whey protein gels were studied. Oil-in-water emulsions of whey protein and vegetable oil were subjected to heat treatment. Such emulsions, depending on their protein and oil content, on their pH and on the emulsification technique used, gelled or remained liquid. Homogenization was the major factor to achieve gelation and the firmness of heat-induced gels increased with increasing emulsion fineness and homogeneity. Emulsions with a high gelation capacity were characterized by a single droplet family of relatively narrow size distribution and a mean droplet diameter ranging from roughly 300–700 nanometers. The pH range suitable for gelation extended from 3.5–8.0.     

Effect of Processing on Proximate Composition and Mineral Content of Sea Cucumbers (Parastichopus spp.)

The nutrient content, texture and holothurin content of two sea cucumber species were determined for fresh, dried and canned products. Fresh sea cucumber contained 89–91% moisture, 5–6% protein, 0.3% fat, 3% ash and 0.3% carbohydrate; dried sea cucumber contained 2–6% moisture, 61–70% protein, 2–3% fat, 16–24% ash, and 2–3% carbohydrate. Fresh sea cucumber contained 90 mg of holothurin per 100g of tissue. Canned sea cucumber contained moisture and protein levels similar to those generally found in marine finfish. Processing methods for canned sea cucumber resulted in a significant (P<0.01) decrease in potassium and increase in sodium. No significant differences (P<0.01) were found in the texture of canned products made from fresh-cooked, salted-cooked and cooked-dried raw material.