Density and rheological parameters of goat milk

The rheological behavior and density of goat milk was studied as a function of solids concentration (10.5 to 50.0%) and temperature (273 to 331 k). Newtonian behavior was observed for values of total solids (TS) between 10.5 and 22.0% and temperatures from 276 to 331 k changing to pseudoplastic behavior without yield stress for TS from 25.0 to 39.4% at the same range of temperature. Goat milk with TS between 44.3 to 50.0% and temperatures of 273 to 296 k showed yield stress in addition to pseudoplastic behavior. At 303 to 331 k the power law model was observed again, without yield stress. The density of goat milk ranged from 991.7 to 1232.4 kg.m-3.

Effect of addition of different hydrocolloids on pasting, thermal, and rheological properties of cassava starch

Starches and gums are hydrocolloids frequently used in food systems to provide proper texture, moisture, and water mobility. Starch-gum interaction in food systems can change the starch granule swelling and its gelatinization and rheological properties. In this study, the effect of the addition of xanthan gum (XG), sodium carboxymethyl cellulose (SCMC), and carrageenan (CAR) at the concentrations of the 0.15, 0.25, 0.35 and 0.45% (w/v) on the pasting, thermal, and rheological properties of cassava starch was studied. The swelling power (SP) and the scanning electron microscopy (SEM) of the starch gels were also evaluated. The results obtained showed that xanthan gum (XG) had a strong interaction with the cassava starch penetrating between starch granules causing increase in pasting viscosities, SP, storage and loss (G', and G", respectively) modulus and reduction in the setback of the starch; sodium carboxymethyl cellulose (SCMC) greatly increased the pasting viscosities, the SP, and the storage and loss (G', and G", respectively) modulus of the starch-mixtures, mainly due to its greater capacity to hold water and not due to the interaction with cassava starch. Carrageenan (CAR) did not change any of the starch properties since there was no interaction between this gum and cassava starch at the concentrations used.

Thermophysical and rheological properties of dulce de leche with and without coconut flakes as a function of temperature

Dulce de leche (DL), a dairy dessert highly appreciated in Brazil, is a concentrated product containing about 70% m/m of total solids. Thermophysical and rheological properties of two industrial Brazilian Dulce de leche formulations (classic Dulce de leche and Dulce de leche added with coconut flakes 1.5% m/m) were determined at temperatures comprised between 28.4 and 76.4 °C. In general, no significant differences (p < 0.05) were observed in the presence of coconut flakes in the two formulations. Heat capacity varied from 2633.2 to 3101.8 J/kg.°C; thermal conductivity from 0.383 to 0.452 W/m.°C; specific mass from 1350.7 to 1310.7 kg/m³; and, thermal diffusivity from (1.082 × 10-7 to 1.130 × 10-7) m²/s. The Bingham model was used to properly describe the non-Newtonian behavior of both formulations, with yielding stress values varying from 27.3 to 17.6 Pa and plastic viscosity from 19.9 to 5.9 Pa.s.

Rheological properties of oil-in-water emulsions prepared with oil and protein isolates from sesame (Sesamum Indicum)

In this study, food emulsions of oil in water from sesame (Sesamum indicum) protein isolates and their oil were formulated and standardised. The effect of the concentrations of sesame (Sesamum indicum) protein isolates and base oil and the speed of the emulsification process for the food emulsion stability was studied. The protein isolates were achieved from the defatted sesame flour (DSF), obtaining a percentage of 80% ± 0.05% of protein. Emulsions were formulated through a factorial design 23. The rheological behaviour of sesame (Sesamum indicum) protein isolates-stabilised emulsions and microstructural composition were investigated. Stable emulsions with suitable rheological properties and microstructure were formulated at a concentration of 10% sesame oil and different concentrations of protein isolates, between 1.5% and 2.5%, with the best droplet distribution characteristics being shown for the 2.5% sesame protein isolates. The emulsions showed a non-Newtonian fluid behaviour, adjusting the Sisko model.

An analysis of decoupling procedures in generating thermal Green's functions of O([lambda]â ´) by the Zubarev equation of motion method

The Zubarev equation of motion method has been applied to an anharmonic crystal of O( ,,4). All possible decoupling schemes have been interpreted in order to determine finite temperature expressions for the one phonon Green's function (and self energy) to 0()\4) for a crystal in which every atom is on a site of inversion symmetry. In order to provide a check of these results, the Helmholtz free energy expressions derived from the self energy expressions, have been shown to agree in the high temperature limit with the results obtained from the diagrammatic method. Expressions for the correlation functions that are related to the mean square displacement have been derived to 0(1\4) in the high temperature limit.

Application of [Lambda] to the fourth perturbation theory in calculating the equation of state of rare gas solids and fcc metals

We have calculated the thermodynamic properties of monatomic fcc crystals from the high temperature limit of the Helmholtz free energy. This equation of state included the static and vibrational energy components. The latter contribution was calculated to order A4 of perturbation theory, for a range of crystal volumes, in which a nearest neighbour central force model was used. We have calculated the lattice constant, the coefficient of volume expansion, the specific heat at constant volume and at constant pressure, the adiabatic and the isothermal bulk modulus, and the Gruneisen parameter, for two of the rare gas solids, Xe and Kr, and for the fcc metals Cu, Ag, Au, Al, and Pb. The LennardJones and the Morse potential were each used to represent the atomic interactions for the rare gas solids, and only the Morse potential was used for the fcc metals. The thermodynamic properties obtained from the A4 equation of state with the Lennard-Jones potential, seem to be in reasonable agreement with experiment for temperatures up to about threequarters of the melting temperature. However, for the higher temperatures, the results are less than satisfactory. For Xe and Kr, the thermodynamic properties calculated from the A2 equation of state with the Morse potential, are qualitatively similar to the A 2 results obtained with the Lennard-Jones potential, however, the properties obtained from the A4 equation of state are in good agreement with experiment, since the contribution from the A4 terms seem to be small. The lattice contribution to the thermal properties of the fcc metals was calculated from the A4 equation of state, and these results produced a slight improvement over the properties calculated from the A2 equation of state. In order to compare the calculated specific heats and bulk moduli results with experiment~ the electronic contribution to thermal properties was taken into account~ by using the free electron model. We found that the results varied significantly with the value chosen for the number of free electrons per atom.

On the equation of state and atomic mean square displacement of crystals

We have presented a Green's function method for the calculation of the atomic mean square displacement (MSD) for an anharmonic Hamil toni an . This method effectively sums a whole class of anharmonic contributions to MSD in the perturbation expansion in the high temperature limit. Using this formalism we have calculated the MSD for a nearest neighbour fcc Lennard Jones solid. The results show an improvement over the lowest order perturbation theory results, the difference with Monte Carlo calculations at temperatures close to melting is reduced from 11% to 3%. We also calculated the MSD for the Alkali metals Nat K/ Cs where a sixth neighbour interaction potential derived from the pseudopotential theory was employed in the calculations. The MSD by this method increases by 2.5% to 3.5% over the respective perturbation theory results. The MSD was calculated for Aluminum where different pseudopotential functions and a phenomenological Morse potential were used. The results show that the pseudopotentials provide better agreement with experimental data than the Morse potential. An excellent agreement with experiment over the whole temperature range is achieved with the Harrison modified point-ion pseudopotential with Hubbard-Sham screening function. We have calculated the thermodynamic properties of solid Kr by minimizing the total energy consisting of static and vibrational components, employing different schemes: The quasiharmonic theory (QH), ).2 and).4 perturbation theory, all terms up to 0 ().4) of the improved self consistent phonon theory (ISC), the ring diagrams up to o ().4) (RING), the iteration scheme (ITER) derived from the Greens's function method and a scheme consisting of ITER plus the remaining contributions of 0 ().4) which are not included in ITER which we call E(FULL). We have calculated the lattice constant, the volume expansion, the isothermal and adiabatic bulk modulus, the specific heat at constant volume and at constant pressure, and the Gruneisen parameter from two different potential functions: Lennard-Jones and Aziz. The Aziz potential gives generally a better agreement with experimental data than the LJ potential for the QH, ).2, ).4 and E(FULL) schemes. When only a partial sum of the).4 diagrams is used in the calculations (e.g. RING and ISC) the LJ results are in better agreement with experiment. The iteration scheme brings a definitive improvement over the).2 PT for both potentials.

Some Travelling Wave Solutions of KdV-Burgers Equation

In this paper we study the extended Tanh method to obtain some exact solutions of KdV-Burgers equation. The principle of the Tanh method has been explained and then apply to the nonlinear KdV- Burgers evolution equation. A finnite power series in tanh is considered as an ansatz and the symbolic computational system is used to obtain solution of that nonlinear evolution equation. The obtained solutions are all travelling wave solutions.

The Wage Rate and the Profit Rate in the Price of Production Equation: a New Solution to an Old Problem

The aim of this paper is to demonstrate that, even if Marx's solution to the transformation problem can be modified, his basic concusions remain valid.

Preparation, characterization, and rheological properties of star-shaped poly(ethylene glycol) with a cholane core and study of its effect on red blood cell aggregation

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Rheological and Extrudate Behaviour of Natural RubberlLatexReclaim Blends

ABSTRACT: The rheological and extrudate behaviour of natural rubber/latex reclaim blends were evaluated using a capillary viscometer . The study shows that the viscosity of natural rubber decreases marginally on the addition of latex reclaim while the variation of viscosity with shear rate is not affected. The temperature sensitivity of the blends is not affected significantly with the addition of latex reclaim . The extrudates of natural rubber/latex reclaim blends are smooth up to the addition of about 50 wt. percent latex reclaim in filled natural rubber compounds.

Rheological Characteristics of Short Nylon -6 Fiber Reinforced Styrene Butadiene Rubber Containing Epoxy Resin as Bonding Agent

The rheological characteristics of short Nylon-6 fiber-reinforced Styrene Butadiene rubber (SBR) in the presence of epoxy resin-based bonding agent were studied with respect to the effect of shear rate, fiber concentration , and temperature on shear viscosity and die swell using a capillary rheonzeter. All the composites containing bonding agent showed a pseudoplastic nature, which decreased with increasing temperature. Shear viscosity was increased in the presence of fibers. The temperature sensitivity of the SBR matrices was reduced on introduction of fibers. The temperature sensitivity of the melts was found to be lower at higher shear rates. Die swell was reduced in the presence of fibers. Relative viscosity of the composites increased with shear rate. In the presence of epoxy resin bonding agent the temperature sensitivity of the mixes increased. Die swell was larger in the presence of bonding agent.

Rheological Properties of Short Polyester Fiber-Polyurethane Elastomer Composite with Different Interfacial Bonding Agents

The rheological behavior of a short-polyester-fiber-filled polyurethane elastomer composite containing different bonding agents has been studied in the temperature range 120-160°C and in the shear rate range 63-608 s-'. The composite with and without bonding agents showed a pseudoplastic behavior which decreased with the increase of temperature. Composites containing bonding agents based on polypropyleneglycol and 4,4'-diphenylmethanediisocyanate showed the lowest viscosity values at a particular shear rate, whereas composites containing a glycerol- (GL) based bonding agent showed the highest viscosity. The viscosity of the composite decreased sharply after a particular temperature (140°C) and the fall was less drastic in the composite containing a GL-based bonding agent.