scholarly journals CHROMATOGRAPHIC, RHEOLOGICAL AND CYTOCHEMISTRY EVALUATION OF “BACURI” PULP (Platonia insignis MART.)

2014 ◽  
Vol 32 (1) ◽  
Author(s):  
ANDRÉA CARDOSO DE AQUINO ◽  
CÍCERO DE SOUZA LIMA ◽  
FILIPE XAVIER FEITOSA ◽  
MARIA IZABEL GALLÃO ◽  
GUSTAVO ADOLFO SAAVEDRA PINTO ◽  
...  
Keyword(s):  
Shear Rate ◽  
Rheological Behavior ◽  
Physicochemical Characterization ◽  
Effect Of Temperature ◽  
Rheological Measurements ◽  
Cytochemical Analysis ◽  
Linalool Oxide ◽  
Increasing Temperature ◽  
Good Agreement ◽  
Newtonian Behavior

“Bacuri” pulp was evaluated for volatile compounds, rheological behavior, and cytochemical analysis. The pulp was also submitted to physicochemical characterization. The effect of temperature on rheological behavior of whole “bacuri” pulp was investigated in this work. The rheological measurements were carried out using a Brookfield Rheometer (Model DV-II +) at shear rate range from 0.25 to 1.50 s-1 at temperatures of 30, 40, 50, 60 and 70 °C. A total of 36 compounds were detected in the headspace of the “bacuri” pulp - 34 of which were identified. The major compounds were the following: linalool, cis-linalool, trans-linalool oxide, and hotrienol, respectively. The experimental data was adjusted using a power law rheological model, with good agreement. “Bacuri” pulp shows a non-Newtonian behavior, with an apparent viscosity decreasing with increasing temperature. The “bacuri” pulp obtained activation energy at shear rate 1.50 s-1 was -14.03 kJ/mol.

The Steady State Rheological Behavior of Semisolid AlSi6Mg2 Alloy

2011 ◽  
Vol 339 ◽  
pp. 257-260 ◽  
Author(s):  
Hong Chao Luo ◽  
Shi Pu Chen ◽  
Qin Nie ◽  
En Sheng Xu ◽  
Li Ping Ju
Keyword(s):  
Steady State ◽  
Shear Rate ◽  
Rheological Behavior ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Solid Particles ◽  
Experimental Results ◽  
Present System ◽  
Flow Conditions ◽  
Good Agreement

In the present work, basing on the rheological model of Chen and Fan (CF) [1] of semisolid metal slurries (SSMS), the rheological behavior at steady state of AlSi6Mg2 alloy is investigated. Experimental results on steady state viscosity of the present system in the literature are used to determine the parameters of the CF model by fitting. It has been shown that the steady state viscosity and the average agglomerate size increase with increasing the solid volume fraction and decreasing the shear rate. The theoretical prediction of the CF model is in good agreement with the experimental results in the literatures quantitatively. The importance of the effective solid volume fraction is shown by explaining the strong coupling between the viscosity and the microstructure. Specifically, the external flow conditions such as shear rate influences the viscosity by changing the agglomeration degree of the solid particles, that is, the effective solid volume fraction and then changing the viscosity.

Study of the Rheological Parameters of Honey Using the Mitschka Method

2009 ◽  
Vol 5 (3) ◽  
Author(s):  
Charles Windson Isidoro Haminiuk ◽  
Giselle M. Maciel ◽  
Manuel Salvador Vicente Plata-Oviedo ◽  
Alessandra Quenehenn ◽  
Agnes P Scheer
Keyword(s):  
Quality Control ◽  
Shear Stress ◽  
Shear Rate ◽  
Temperature Effect ◽  
Rheological Behavior ◽  
Food Industry ◽  
Experimental Results ◽  
Rheological Parameters ◽  
Quality Control Testing ◽  
Newtonian Behavior

In this work the rheological behavior of two varieties of honey were evaluated using a Brookfield viscometer R.V.T in a temperature range of 5-20°C. In order to interpret the experimental results in terms of viscosity, the torque-speed data and scale readings were converted into shear stress-shear rate relations using numerical conversion values proposed by Mitschka. This method offers excellent potential for quality control testing in the food industry. Samples exhibited Newtonian behavior and the temperature effect on the viscosity followed an Arrhenius-type relationship.

Rheological Behavior of Bamboo Charcoal PET

2011 ◽  
Vol 224 ◽  
pp. 240-244
Author(s):  
Li Na Wang ◽  
Zhao Xi Deng ◽  
Yan Wei Wang
Keyword(s):  
Shear Rate ◽  
Rheological Behavior ◽  
Viscosity Index ◽  
Bamboo Charcoal ◽  
Structural Viscosity ◽  
Rheological Models ◽  
Rate Range ◽  
Rheological Measurements ◽  
Shear Thinning Fluid ◽  
Master Batch

In this paper some of rheological properties of bamboo charcoal polyester (BC-PET) are presented. The BC-PET is derived from PET modified through commix with bamboo charcoal master batch. The additive content of blends ranged between 0% and 10%. Rheological measurements were effectuated with a Brookfield viscometer (RVDV-II+Pro). The results showed that molten BC-PET exhibited shear thinning fluid, these were verified with some rheological models. Non-Newtonian index decreased significantly and structural viscosity index increased obviously with the master-batch content increased, but the viscosity was stable in the shear rate range of spinning (γ=103-104s-1), so decreased the temperature was beneficial to spinning.

scholarly journals Aqueous Solutions of Polyethoxylated Fatty Alcohols Rheological behavior and superficial properties

2019 ◽  
Vol 70 (2) ◽  
pp. 382-386
Author(s):  
Andra Tamas ◽  
Sabina Nitu
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Aqueous Solutions ◽  
Rheological Behavior ◽  
Flow Behavior ◽  
Fatty Alcohols ◽  
Flow Behavior Index ◽  
Foaming Power ◽  
Newtonian Behavior ◽  
Behavior Index

The paper presents the study of the rheological and superficial behavior (foaming power and wetting capacity) of some aqueous solutions with polyethoxylated fatty alcohols content. The influence of fatty alcohols concentration and their degree of ethoxylation as well as that of temperature on the rheological behavior was determined from the dependences between the shear stress t and the shear rate. The results demonstrate that all the studied solutions have non-Newtonian behavior, with flow behavior index smaller than 1.

Effect of temperature on the rheological behavior of sugary cassava

2020 ◽  
pp. 125
Author(s):  
Leiliane do Socorro Sodré Souza ◽  
Tatiane Pereira de Souza ◽  
Rafael Lopes e Oliveira ◽  
Sérgio Duvoisin Junior ◽  
Ari de Freitas Hidalgo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Shear Rate ◽  
Rheological Behavior ◽  
Food Production ◽  
Arrhenius Equation ◽  
Effect Of Temperature ◽  
Rheological Models ◽  
Rate Range ◽  
Fermented Beverages ◽  
Three Samples

The rheological behavior of the juice extracted from sugary cassava roots, a type of cassava that stored the largest amount of sugars and the starch as it was, at various temperatures (9-65ºC) and in concentrations of 5ºBrix, 10.5ºBrix, and 18.5ºBrix. The experiments were performed on a Brookfield viscometer in a shear rate range of 0.01-237.6 s-1. The rheological models of Newton, Bingham, and Ostwald-De-Waele were fitted to the experimental results. The Newton model describes well the rheological behavior of the three samples evaluated. The effect of temperature on viscosity was evaluated using an Arrhenius equation; the viscosity value is influenced by the same temperature. The activation energy values ​​for the concentrations of 5ºBrix, 10.5ºBrix and 18.5ºBrix correspond to 3.14 kcal mol-1, 3.53 kcal mol-1 and 3.71 kcal mol-1. This type of cassava can be used in the production of ethanol, fermented beverages and syrups. It is also an important alternative for food production, as the cultivation of cassava can be classified as less aggressive to the environment, in comparison with sugarcane.

scholarly journals Experimental and finite element study of the effect of temperature and moisture on the tangential tensile strength and fracture behavior in timber logs

Holzforschung ◽  
2014 ◽  
Vol 68 (1) ◽  
pp. 133-140 ◽  
Author(s):  
Finn Larsen ◽  
Sigurdur Ormarsson
Keyword(s):  
Finite Element ◽  
Tensile Strength ◽  
Fracture Behavior ◽  
Maximum Stress ◽  
Climatic Conditions ◽  
Effect Of Temperature ◽  
Modeling And Experiments ◽  
Temperature Levels ◽  
Increasing Temperature ◽  
Good Agreement

Abstract Timber is normally dried by kiln drying, in the course of which moisture-induced stresses and fractures can occur. Cracks occur primarily in the radial direction due to tangential tensile strength (TSt) that exceeds the strength of the material. The present article reports on experiments and numerical simulations by finite element modeling (FEM) concerning the TSt and fracture behavior of Norway spruce under various climatic conditions. Thin log disc specimens were studied to simplify the description of the moisture flow in the samples. The specimens designed for TS were acclimatized to a moisture content (MC) of 18% before TSt tests at 20°C, 60°C, and 90°C were carried out. The maximum stress results of the disc simulations by FEM were compared with the experimental strength results at the same temperature levels. There is a rather good agreement between the results of modeling and experiments. The results also illustrate the strong decrease of TSt with increasing temperature at a constant MC level.

Rheological Behavior and Fluidity of Semi-Solid SiCp/A357 Composites with Different SiC Addition Levels

2016 ◽  
Vol 256 ◽  
pp. 126-132 ◽  
Author(s):  
Zhen Lin Zhang ◽  
Zhi Feng Zhang ◽  
Jun Xu ◽  
Wei Min Mao
Keyword(s):  
Shear Rate ◽  
Solid Fraction ◽  
Rheological Behavior ◽  
Apparent Viscosity ◽  
Stir Casting ◽  
Sic Particles ◽  
Semi Solid ◽  
Test Casting ◽  
Good Agreement

The apparent viscosities of the semi-solid SiCp/A357 composites with 0vol.%, 10vol.% and 20vol.% SiC particles manufactured by stir casting were investigated using a Couette type viscometer, and the composite fluidity was examined with a test casting. The results showed that, the viscosities of the semi-solid SiCp/A357 composites decreased with an increase in shear rate, but increased with the increasing of solid fraction, and apparent viscosity of 10vol.% SiCp/A357 composite was the lower than that of 20vol.% SiCp/A357 composite at the same solid fraction; and the composite fluidity results were in a good agreement with the viscosity ones.

scholarly journals Rheological Properties of Some Honeys in Liquefied and Crystallised States

2016 ◽  
Vol 60 (2) ◽  
pp. 153-166 ◽  
Author(s):  
Sławomir Bakier ◽  
Krzysztof Miastkowski ◽  
Jan Robert Bakoniuk
Keyword(s):  
Quantitative Analysis ◽  
Shear Rate ◽  
Dynamic Viscosity ◽  
Apparent Viscosity ◽  
Steady Shear ◽  
Dynamic Measurements ◽  
Rheological Measurements ◽  
Rotary Shear ◽  
The Media ◽  
Good Agreement

Abstract The paper presents the results of rheological measurements conducted on three types of Polish honey: rape, multi-floral, and buckwheat honeys. The investigations involved identification of the properties of the honeys in both liquefied (by heating) as well as crystallised states. Both steady shear as well as dynamic rheological tests were performed. As a result, it was possible to show that the liquefied honeys behave like Newtonian fluids. Good agreement of the results between the rotary shear and oscillation rotary tests was observed, thus fulfilling the Cox-Mertz rule. The structure of the honeys was subjected to qualitative scrutiny by analysing photographs of the crystals taken in the conditions of shearing interferometry. The quantitative analysis was made by presenting a numerical distribution of crystal colonies with reference to the maximum dimensions of individual crystals. The geometric measurements of the crystals were carried out using analiSIS software. In the crystallised form, the media showed a thixotropic effect, and their apparent viscosity was many times higher than the dynamic viscosity in the liquid state. After plasticising by deformation with an increasing shear rate of up to 450s−1, the equilibrium melting curves of the crystallised honeys were described by the Ostwald-de Waele model. One particular reason for the research was to show that the results obtained for the honeys crystallised by the steady shear method, were qualitatively different from the results obtained in the dynamic measurements. The Cox-Mertz rule cannot be applied for the crystallised honeys.

A Steady State Model for the Rheological Behavior of Semisolid Al-6.5wt%Si Alloy

2011 ◽  
Vol 228-229 ◽  
pp. 858-863
Author(s):  
Li Ping Ju ◽  
Hong Chao Luo ◽  
Wei Wang ◽  
Dan Xu
Keyword(s):  
Steady State ◽  
Shear Rate ◽  
Rheological Behavior ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Solid Particles ◽  
State Behavior ◽  
Packing Parameter ◽  
Steady State Model ◽  
Good Agreement

In the present work, The Chen and Fan (CF) model [1] of semisolid metal slurries (SSMS) is improved by modifying the expression of the packing parameter, of the solid particles and then the modified CF (MCF) model is obtained. Subsequently, the MCF model is applied to the Al-6.5wt%Si alloy to investigate its rheological behavior at steady state. The factors which affect the steady state behavior have been studied. It has been shown that the steady state viscosity and the average agglomerate size increase with increasing the solid volume fraction and decreasing the shear rate. The prediction of the model is in good agreement with the experimental results in the literatures qualitatively. The importance of the effective solid volume fraction is shown by explaining the strong coupling between the viscosity and the microstructure. The external flow conditions such as shear rate etc change the agglomeration degree, that is, the effective solid volume fraction and then the viscosity

scholarly journals Theoretical Effect of Temperature on Threshold in the Hodgkin-Huxley Nerve Model

1966 ◽  
Vol 49 (5) ◽  
pp. 989-1005 ◽  
Author(s):  
Richard Fitzhugh
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Giant Axon ◽  
Temperature Curve ◽  
Effect Of Temperature ◽  
Threshold Temperature ◽  
Ionic Conductances ◽  
And Shifts ◽  
The Right ◽  
Increasing Temperature

In the squid giant axon, Sjodin and Mullins (1958), using 1 msec duration pulses, found a decrease of threshold with increasing temperature, while Guttman (1962), using 100 msec pulses, found an increase. Both results are qualitatively predicted by the Hodgkin-Huxley model. The threshold vs. temperature curve varies so much with the assumptions made regarding the temperature-dependence of the membrane ionic conductances that quantitative comparison between theory and experiment is not yet possible. For very short pulses, increasing temperature has two effects. (1) At lower temperatures the decrease of relaxation time of Na activation (m) relative to the electrical (RC) relaxation time favors excitation and decreases threshold. (2) For higher temperatures, effect (1) saturates, but the decreasing relaxation times of Na inactivation (h) and K activation (n) factor accommodation and increased threshold. The result is a U-shaped threshold temperature curve. R. Guttman has obtained such U-shaped curves for 50 µsec pulses. Assuming higher ionic conductances decreases the electrical relaxation time and shifts the curve to the right along the temperature axis. Making the conductances increase with temperature flattens the curve. Using very long pulses favors effect (2) over (1) and makes threshold increase monotonically with temperature.

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