Flavor and oxidative stability of northern-grown sunflower seed oil

Flavor and oxidative stabilities of a northern-grown sunflower seed oil were investigated. Taste panel and oxidative evaluations were made on alkali-refined, deodorized, unbleached samples treated with commercial antioxidant mixtures, phenolic antioxidants, metal scavengers and added trace metals. Similar evaluations were conducted on a sample of the same oil after bleaching. Commercial antioxidant mixtures containing both phenolic antioxidants and a metal scavenger improve the flavor and oxidative stabilities of refined unbleached oil. Although phenolic antioxidants alone improve oxidative stability as measured by the active oxygen method test, flavor stability did not improve significantly for antioxidant-treated refined, unbleached samples after accelerated storage. Conversely, alkali-refined and bleached sunflower oil responded to treatment with certain phenolic antioxidants. Although iron and copper are deleterious to oil stability at concentrations of 0.1 ppm, such metal-inactivating agents as citric acid are effective in improving flavor stability. N. Market. Nutr. Res. Div., ARS, USDA.     

Analysis of free hormone fractions by an ultrafast immunoextraction/displacement immunoassay: studies using free thyroxine as a model system

A system was developed for measuring the noncomplexed or free fraction of a hormone in serum based on the combined use of ultrafast immunoextraction with a chromatographic displacement immunoassay. This approach was tested using L-thyroxine as a model analyte. Items considered in the development of this technique included the choice of immunoassay format and the selection of conditions for removal of thyroxine's free fraction from samples without significant interference from its protein-bound fraction. The final method had an effective extraction time of 90 ms and allowed the amount of free thyroxine to be determined within 30 s after sample injection. The limit of detection was 6 pM (S/N = 3) for a 100-microL sample, and the linear response extended up to at least 100 pM. This technique gave good correlation versus reference methods when used for the determination of free thyroxine in serum samples. Advantages of this method included its speed and its ability to analyze a sample with no pretreatment other than standard filtration. The same approach could be adapted for other hormones or drugs by using appropriate antibodies and labeled analogues for such agents.     

Tunable microfluidic microlenses

A novel type of liquid microlens, bounded by a microfabricated, distensible membrane and activated by a microfluidic liquid-handling system, is presented. By use of an elastomer membrane fabricated by spin coating onto a dry-etched silicon substrate, the liquid-filled cavity acts as a lens whereby applied pressure changes the membrane distension and thus the focal length. Both plano-convex and plano-concave lenses, individual elements as well as arrays, were fabricated and tested. The lens surface roughness was seen to be approximately 9 nm rms, and the focal length could be tuned from 1 to 18 mm. This lens represents a robust, self-contained tunable optical structure suitable for use in, for example, a medical environment.     

Importance-driven feature enhancement in volume visualization

This paper presents importance-driven feature enhancement as a technique for the automatic generation of cut-away and ghosted views out of volumetric data. The presented focus+context approach removes or suppresses less important parts of a scene to reveal more important underlying information. However, less important parts are fully visible in those regions, where important visual information is not lost, i.e., more relevant features are not occluded. Features within the volumetric data are first classified according to a new dimension, denoted as object importance. This property determines which structures should be readily discernible and which structures are less important. Next, for each feature, various representations (levels of sparseness) from a dense to a sparse depiction are defined. Levels of sparseness define a spectrum of optical properties or rendering styles. The resulting image is generated by ray-casting and combining the intersected features proportional to their importance (importance compositing). The paper includes an extended discussion on several possible schemes for levels of sparseness specification. Furthermore, different approaches to importance compositing are treated.     

Soybean unsaponifiables: Chromatographic separations and characterization

Unsaponifiables extracted from 10 different lots of refined soybean oil were subjected to liquidliquid chromatographic separations. Three major fractions were obtained. The least polar hydrocarbon fraction constituted 15 to 30% of the unsaponifiables; the most highly polar fraction contained the steroids constituting 35 to 45% of the unsaponifiables. The fraction of intermediate polarity varied in composition from lot to lot, but usually it contained more than 50% of the unsaponifiables. These basic fractions were analyzed by thin layer, gas-liquid chromatography, and by chemical tests for functional groups. To determine the effects of soybean unsaponifiables on the oxidative and organoleptic stability of edible fats, various concentrations of the extracted and fractionated materials were examined in cottonseed oil. Effects of extraction methods on yields, fractionation characteristics, and composition of the different lots of soybean unsaponifiables are discussed. Presented at the AOCS meeting in Chicago, 1961. Division, Agricultural Research Service, USDA.