Subsolidus Compatibility in the System NaCl-KCl-AlCl3-NaF-KF-AlF3

The chemistry and properties of salts used as fluxes for recycling aluminum were studied. Many fluxing salts fall within the system NaCl-KCl-AlCl₃-NaF-KF-AlF₃, which has been shown to be a reciprocal system, with NaF-KCl, KC1-AIF₃, and NaCl-AIF₃ as the stable mixed-halide binaries. Twelve subsolidus compatibility tetrahedra were determined by X-ray analyses of samples heated in evacuated sealed tubes. X-ray measurements of quenched and annealed samples indicate that elpasolite, nominally K₂NaAlF₆, has a compositional range between 60 mo% Na₃AlF₆, 40 mol% K₃AlF₆ and 25 mol% Na₃AlF₆, 75 mol% K₃AIF₆. Improved X-ray powder data are given for KAIF₄, showing a previously reported structure to be essentially correct.     

Thermodynamic Assessment of the System MnO-NiO

The thermodynamic properties of pure MnO and NiO were analyzed in terms of the Debye model and a model for the magnetic transitions. The classical formula R In (β+ 1) for the magnetic entropy was found to overestimate the effect of magnetic ordering in these systems. A previous interpretation of the data for NiO was corrected. Thermodynamic functions were derived for the solid and liquid states and are given as analytic expressions. A previous assessment of the Gibbs energy of the solid solution (Mn, Ni)O from activity data was modified on statistical grounds. The results indicate that there should be a miscibility gap below 41O°C. By estimating the Gibbs energy of the liquid phase, it was possible to calculate the complete phase diagram.     

Feasibility of a Composite of Sic Whiskers in an MoSi2 Matrix

A composite consisting of 20 vol% Sic whiskers in a hot-pressed MoSi₂ matrix was investigated. The composite displayed an ∼100% increase inflexural strength and a 54% improvement in fracture toughness, compared to the values measured for the matrix material. The improvements are attributed to the change in the micro-structure of the MoSi₂ afforded by the presence of the whiskers.     

EFFECT OF SODIUM LACTATE, CALCIUM LACTATE AND SODIUM ALGINATE ON BACTERIAL GROWTH AND AMINOPEPTIDASE ACTIVITY

The effects of sodium alginate (0.4 and 0.8%), calcium lactate (0.15 and 0.3%) and sodium lactate (60% solution; 1, 2, 3 and 4%) on growth and aminopeptidase activity of Pseudomonas fragi ATCC 4973 and Salmonella typhimurium in trypticase soy broth or autoclaved ground beef were studied for 5 days at 5°C. Sodium alginate and calcium lactate did not change colony counts of P. fragi or S. typhimurium; and had only slight effects on aminopeptidase activity. Sodium lactate (3 and 4%) showed inhibitory activity on growth and aminopeptidase activity of P. fragi. Sodium lactate also decreased aminopeptidase activity of S. typhimurium but had no major influence on colony counts. In general, aminopeptidase activity was inhibited more than cell multiplication by higher levels of alginate and sodium lactate .     

Optimal location of process measurements

The problem of optimally locating a given number of Bensors for observing a general linear distributed parameter system is considered. Measurements at the sensors are assumed to be available continuously in time, and the design criterion is minimization of a scalar measure of the covariance of the estimate error in the optimal linear filter. Necessary conditions for optimality are derived based on the formulation of a distributed parameter matrix minimum principle. A computational algorithm is developed for determining the optimum set of measurement locations. The algorithm is applied to the problem of optimally locating temperature sensors in a solid undergoing transient heat conduction.     

An assessment of OH airglow interference on the remote sensing of stratospheric HC1 via limb sounding in the near-I.R.

Chemiluminescent emission from the formation of vibrationally excited OH at an altitude of approximately 85 km presents a barrier to Earth limb measurements of near-infrared emissions originating in the stratosphere. High resolution measured spectra of OH airglow in the region of interest have not been reported, and thus it is difficult to assess its impact on moderately high resolution Earth limb spectroscopy capable of looking between strong OH lines. Low resolution rocket-borne spectrometer Earth limb measurements of OH airglow arc mathematically inverted to recover vibrational state populations that are used to simulate a higher resolution spectrum in the neighbourhood of 2843cm^-1, Implications for remote sensing HCI are presented.     

Hygroscopic Coatings Control Surface White Discoloration of Peeled (Minimally Processed) Carrots During Storage

White discoloration on peeled carrots is partially due to surface dehydration which can be controlled with hygroscopic coatings: e.g., polyhydric alcohols and salt solutions. This study was performed at 2.5, 7.5, 10, and 15°C, using a model system controlling relative humidity at 33, 75 or 98% or a commercial system with low-density polyethylene (LDPE) plastic film bags. The moisture sorption properties of propylene glycol, sorbitol, glycerol and calcium chloride enabled them to keep the carrot surface moist and maintain a transparent surface layer through which the underlying orange color was visible. This effect was only observed at high relative humidities (e.g., 98% RH). Similar effects were observed on treated peeled carrots stored in LDPE bags. The moisturized appearance provided by the hygroscopic coatings during storage was effective at several different temperatures.