Steam-Refined soybean oil: I. effect of refining and degumming methods on oil quality

A lot of commercially extracted crude soybean oil was water degummed with and without a phosphoric acid pretreatment. The degummed oils were bleached and then deacidified-deodorized in a single step to yield physically (steam) refined soybean salad oils. Their flavor and oxidative stability were compared to caustic-refined oils given otherwise identical processing treatments. Physically refined oils without a phosphoric acid pretreatment were of poor initial quality compared to those given the phosphoric acid pretreatment. However, caustic- and steam-refined oils processed with the phosphoric pretreatment were of comparable quality. Presented in part at the AOCS-AACC Symposium, Current Concepts of Food Ingredients, Chicago, March 1977.     

Continuous ultrasonic hydrogenation of soybean oil. II. Operating conditions and oil quality

In previous work we found that ultrasonic energy greatly enhanced the rate of hydrogenation of soybean oil. We have now investigated parameters of ultrasonic hydrogenation and the quality of the resulting products. Refined and bleached soybean oil was hydrogenated continuously with and without ultrasonic energy at different temperatures, pressures and catalyst concentrations. Flavor and oxidative stability of the oils were compared with a commercially hydrogenated soybean oil. The extent of hydrogenation (ΔIV) was not affected by temperature between 245 and 290 C, but was greater at 106 psig than at 65 psig hydrogen pressure. The ΔIV of hydrogenated oils increased linearly with catalyst concentration from 40 ppm to 150 ppm nickel. At the same catalyst concentration the IV drop was significantly increased when ultrasonic energy was used. By reducing the amount of power supplied to the ultrasonic reactor to 40% of full power, the specific power (watts/ΔIV) was lowered by 60%. Linolenate selectivities and specific isomerization (%trans/ΔIV) remained the same, but linoleate selectivities were lower than for batch hydrogenation under varied operating parameters. Flavor scores were not significantly different, initially or after storage eight days at 60 C, for oils continuously hydrogenated with and without ultrasonic energy. Hydrogenation of soybean oil with ultrasonic energy offers a method to produce good quality products at potentially lower cost than present methods.     

Origins and implications of temperature-dependent activation energy barriers for dislocation nucleation in face-centered cubic metals

The linking of atomistic simulations of stress-driven processes to experimentally observed mechanical behavior via the computation of activation energy barriers is a topic of intense current research. Using dislocation nucleation from a crack tip as the reaction process, long-time multiscale molecular dynamics simulations show that the activation barrier can exhibit significant temperature dependence. Using an analytic model for the nucleation process and computing the relevant material properties (elastic constants and stacking fault energies), the temperature dependence is shown to arise primarily from the temperature dependence of the material parameters for both Al and Ni. After thermally activated emission of the first partial dislocation, there is then a competition between two other thermally activated processes: twinning and full dislocation emission. Because the activation barriers depend on temperature, this transition is more complex than usually envisioned. Simulations in Al reveal that a transition from twinning to full dislocation emission back to twinning occurs with increasing temperature, which is counter to traditional metallurgical wisdom. Temperature-dependent activation energies are thus essential to accurate understanding and prediction of those phenomena that control fracture and deformation in metals at realistic loading rates.     

Accuracy of clinical assessment of deep-vein thrombosis

The clinical diagnosis of deep-vein thrombosis is generally thought to be unreliable. From experience, we hypothesised that this widely held view might be incorrect. We developed a clinical model and prospectively tested its ability in three tertiary care centres to stratify symptomatic outpatients with suspected deep-vein thrombosis into groups with high, moderate, or low probability groups of deep-vein thrombosis. We evaluated our clinical model in combination with venous ultrasonography to determine the potential for an improved and simplified diagnostic approach in patients with suspected deep-vein thrombosis. All patients were clinically assessed to determine the probability for deep-vein thrombosis before they had ultrasonography and venography. All tests were performed and interpreted by independent observers. In 529 patients, the clinical model predicted prevalence of deep-vein thrombosis in the three categories: 85% in the high pretest probability category, 33% in the moderate, and 5% in the low category. There was no statistical difference in the performance of the model in the three centres. The model demonstrated excellent interobserver reliability (Kappa = 0.85). There were important differences with ultrasonography between the high and low pretest probability groups for both positive predictive values (100% (95% CI, 94-100%) vs (63% [35-85%], respectively). Thus, use of the clinical model combined with ultrasonography would decrease the number of false positive and negative diagnosis if venography were done when the ultrasound result and pretest probability were discordant. The diagnostic process could be simplified by excluding those patients with low pretest probability and normal ultrasound results from serial testing.     

A comparison of radiographic and electrogoniometric angles in adolescent idiopathic scoliosis

STUDY DESIGN: This was a cross-sectional study of a consecutive group of adolescent patients presenting to a scoliosis clinic for routine assessment or monitoring of their scoliosis, excluding postsurgical patients. SUMMARY OF BACKGROUND DATA: In vitro studies suggested electrogoniometry could be useful in the evaluation of scoliosis. No prior in vitro study had been performed. OBJECTIVES: To determine the reliability and validity of an electrogoniometric instrument, the Metrecom Skeletal Analysis System, in assessing adolescent idiopathic scoliosis. METHODS: Thirty-one patients were examined, radiographed, and scanned with the Metrecom Skeletal Analysis System twice by two different examiners. The magnitudes of the curves derived from the Metrecom Skeletal Analysis System scans were compared with each other and with the Cobb angles measured from standing radiographs. RESULTS: The intraclass correlation coefficient (a measure of agreement, ranging from 0 to 1, where 1 represents complete agreement) for the intraexaminer reliability of the Metrecom Skeletal Analysis System ranged from 0.71 to 0.83. The interexaminer reliability intraclass correlation coefficient of the Metrecom Skeletal Analysis System was 0.58, with a mean difference between examiners of 5.5 degrees (SD = 5 degrees), and limits of agreement (mean difference +/-2 SD) ranging from -4.5 degrees to 15.6 degrees. The Metrecom Skeletal Analysis System and the radiographically derived Cobb angle correlation was 0.64, but the mean difference between the methods was 3.7 degrees (SD = 11.1), with limits of agreement from 18.4 degrees to 25.9 degrees. CONCLUSION: The Metrecom Skeletal Analysis System does not provide sufficient clinical precision to substitute for the Cobb angle measured from spinal radiographic measurements in the management of adolescents with scoliosis.     

Development of crosslinked polyamines suitable for synthesizing complex ampholytes for isoelectric focusing

Commercially available ampholytes used in isoelectric focusing applications vary widely from source to source in their resolving power. This study was initiated to develop alternative ampholyte formulations for high resolution preparative and analytical isoelectric focusing. Initial IR spectroscopy studies showed that divalent acid esters would efficiently crosslink available polyamines with complete consumption of ester. Fast atom bombardment mass spectroscopic analysis of resulting crosslinked polyamines showed extensive structural heterogeneity of the resulting polyamine mixture. Conversion of the polyamine mixture to functional zwitterions using alpha,beta-unsaturated carboxylic acids yielded mixtures giving smooth pH gradients in acrylamide gel isoelectric focusing. Further analysis of these mixtures in immobilized pH gradients showed increases in heterogeneity of available carrier species over similar zwitterion mixtures made using only commercially available polyamine monomers. The mixtures were also more heterogeneous than commercially available ampholytes when analyzed by picric acid precipitation in immobilized pH gradients.     

Substrate coupling in digital circuits in mixed-signal smart-power systems

This paper describes theoretical and experimental data characterizing the sensitivity of nMOS and CMOS digital circuits to substrate coupling in mixed-signal, smart-power systems. The work presented here focuses on the noise effects created by high-power analog circuits and affecting sensitive digital circuits on the same integrated circuit. The sources and mechanism of the noise behavior of such digital circuits are identified and analyzed. The results are obtained primarily from a set of dedicated test circuits specifically designed, fabricated, and evaluated for this work. The conclusions drawn from the theoretical and experimental analyses are used to develop physical and circuit design techniques to mitigate the substrate noise problems. These results provide insight into the noise immunity of digital circuits with respect to substrate coupling.