Modeling the thermodynamic properties of sodium chloride in steam through extended corresponding states

Recent precise data on anomalous behavior of apparent molar properties of electrolyte solutions in near-critical steam have raised important questions as to how the thermodynamic properties of these systems should be described. Current Gibbs free energy models fail for highly compressible solutions. Here, a Helmholtz free energy formulation is presented as a first step in modeling compressible dilute aqueous electrolyte solutions. Comparisons are made with the known critical line, coexistence curves, apparent molar volumes, and heat capacities of NaCl in steam, and conclusions presented on improving the model.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Two Periodic Review inventory Models with Backorders and Stuttering Poisson Demands

Two periodic review inventory models, (R, T) and (nQ, r, T), are analyzed for the situation where demands are characterized by either a Poisson or stuttering Poisson process. In each model, backorders are allowed and the procurement lead time is considered to be a constant. Average annual cost equations are developed for each model and solution techniques presented, so that minimum average annual costs can be determined. A numerical example is also presented. It is shown for large times between reviews that the (R, T) and (nQ, r, T) models are essentially equivalent.     

Crystal chemistry of catalyst materials. I. Composition and unit cell parameters of “REMnO3” phases prepared in air

Oxygen stoichiometry and manganese valences have been determined for “REMnO₃” phases prepared in air where RE are the rare earths from Nd to Lu including Y but excluding Tb. All of the phases had a slight oxygen deficiency and partial Mn²⁺ for Mn³⁺ substitution. This contrasts with “LaMnO₃” which is known to have extensive Mn⁴⁺ for Mn³⁺ substitution when prepared in air.     

Evaluation of laser absorption spectroscopic techniques for eddy covariance flux measurements of ammonia

An intercomparison was made between eddy covariance flux measurements of ammonia by a quantum cascade laser absorption spectrometer (QCLAS) and a lead-salt tunable diode laser absorption spectrometer (TDLAS). The measurements took place in September 2004 and again in April 2005 over a managed grassland site in Southern Scotland, U.K. These were also compared with a flux estimate derived from an "Ammonia Measurement by ANnular Denuder with online Analysis" (AMANDA), using the aerodynamic gradient method (AGM). The concentration and flux measurements from the QCLAS correlated well with those of the TDLAS and the AGM systems when emissions were high, following slurry application to the field. Both the QCLAS and TDLAS, however, underestimated the flux when compared with the AMANDA system, by 64%. A flux loss of 41% due to chemical reaction of ammonia in the QCLAS (and 37% in the TDLAS) sample tube walls was identified and characterized using laboratory tests but did not fully accountforthis difference. Recognizing these uncertainties, the agreement between the systems was nevertheless very close (R2 = 0.95 between the QCLAS and the TDLAS; R2 = 0.84 between the QCLAS and the AMANDA) demonstrating the suitability of the laser absorption methods for quantifying the temporal dynamics of ammonia fluxes.     

Fundamental rheological and textural properties of doughs and breads produced from milled pearled barley flour

Barley has long been known as a good source of fibre and in particular beta-glucan, but increased consumer awareness has meant that this is only now being exploited by food scientists and the food industry. In this study, doughs and breads were produced using pearled barley flour (PBF) in different ratios (30, 50, 70 and 100%) to wheat flour. A 100% wheat flour formulation was used as a control. The flour formulations were evaluated for protein content; the dough rheological properties of the formulations were evaluated using fundamental oscillatory tests and uniaxial extension tests. The baked breads were evaluated for volume, texture, moisture, dietary fibre and beta-glucan. Digital image analysis of the crumb grain was also carried out. Protein analysis revealed that increasing the amount of PBF in the formulation leads to a significant (p < 0.001) decrease in the protein content of the formulation. Starch pasting properties were also affected by an increase in PBF concentration, with an increase in PBF significantly increasing the peak viscosity, breakdown, setback and final viscosity of the starch slurries of the formulations. Extensional rheology revealed that increasing the PBF in the doughs leads to the doughs rupturing at lower extensions and with a lower force. Bread volume between treatments was found to be significantly (p ≤ 0.001) different, with an increase in PBF inclusion leading to smaller loaves. Texture profile analysis of the bread slices showed that breads containing higher ratios of PBF had a significantly harder (p ≤ 0.001) and less cohesive (p ≤ 0.001) crumb. Low levels of PBF (≤50%) did not significantly effect loaf volume or crumb texture, however, and the total dietary fibre and beta-glucan levels of the loaves were significantly increased (p ≤ 0.001) with increasing levels of PBF in the formulation, even at low levels of inclusion.