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Relaxation Curves (relaxation + curve)
Selected AbstractsCHARACTERISTICS OF GELLAN GUM BASED FOOD GELSJOURNAL OF TEXTURE STUDIES, Issue 4 2010DIPJYOTI SAHA ABSTRACT Fruit-based gels with gellan gum as the gelling agent was prepared. Textural attributes of the gellan gum gels, formed with different concentrations of the gum (0.5,3.0%) and sugar and/or pineapple juice, were determined employing the methods of large-deformation uniaxial compression and stress relaxation. Fracture stress/energy markedly increases with an increase in the concentration of gellan gum while fracture strain exhibits a marginal effect. The change in these compressive textural parameters is more pronounced for sugar added samples compared with gels without sugar. Marked decay in stress relaxation curves was observed; the extent of relaxation decreases marginally with an increase in gum content up to 2% but shows much lesser values beyond 2% addition. The sugar added samples exhibit lesser relaxation characteristics but higher relaxation times indicating elastic characteristics compared with samples without sugar. Use of gellan gum provides an innovative method for developing fruit juice based gels as a convenience food because of attractive transparent appearance and textural attributes. PRACTICAL APPLICATION The use of hydrocolloids like gellan gum can develop fabricated foods in the form of fruit juice based gels having unique textural properties. These properties can be altered to suit the consumer preference by varying the proportions of gellan gum, fruit juice and sugar. The results in the present investigation arising from compression and relaxation testing thus help in characterizing the developed gels. [source] Effect of gluten content on recrystallisation kinetics and water mobility in wheat starch gelsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2004Xin Wang Abstract The effect of gluten on starch retrogradation at 5 °C was studied using 1H NMR relaxometry. Gels were made from gluten and starch at 27.8 and 38.5% total solids and with gluten comprising either 10, 15 or 20% of the solids. Changes in the transverse relaxation time constant (T2) were related to water mobility. Mono-exponential analysis of relaxation curves showed that, in general, gluten retarded starch retrogradation. T2 values in gluten gels also decreased during storage, but to a much lesser extent. Distributed exponential analysis showed that two distinct regions of T2 were observed in all samples. During aging, the peak values of both regions shifted to lower values for all gels. Starch gel samples showed the most significant shift, and gluten gels showed the least. The three levels of gluten addition in starch/gluten gels produced similar shifts. For all samples the signal intensity of the less mobile region decreased more dramatically than that of the more mobile region during storage. It was suggested that gluten retards water loss in the granule remnants. Copyright © 2004 Society of Chemical Industry [source] Strain-Controlled Tensile Deformation Behavior and Relaxation Properties of Isotactic Poly(1-butene) and Its Ethylene CopolymersMACROMOLECULAR SYMPOSIA, Issue 1 2004Mahmoud Al-Hussein Abstract The tensile deformation behaviour of poly(1-butene) and two of its ethylene copoloymers was studied at room temperature. This was done by investigating true stress-strain curves at constant strain rates, elastic recovery and stress relaxation properties and in-situ WAXS patterns during the deformation process. As for a series of semicrystalline polymers in previous studies, a strain-controlled deformation behaviour was found. The differential compliance, the recovery properties and the stress relaxation curves changed simultaneously at well-defined points. The strains at which these points occurred along the true stress-strain remained constant for the different samples despite their different percentage crystallinities. The well-defined way in which the different samples respond to external stresses complies with the granular substructure of the crystalline lamellae in a semicrystalline polymer. [source] 29Si spin-lattice NMR relaxation in microporous silica-based materials with high Mn2+ concentrationsMAGNETIC RESONANCE IN CHEMISTRY, Issue 11 2006Vladimir I. Bakhmutov Abstract The 29Si T1 time measurements have been performed under magic angle spinning for supermicroporous Si/Mn materials 1,6 containing Mn2+ in concentrations of 0 (1), 1.2 (2), 2.5 (3), 3.8 (4), 15 (5) and 19.8 wt% (6). It has been found that the central lines, corresponding to isotropic chemical shifts, and their sidebands relax differently in samples 2,4 with relatively small Mn2+ contents. Because the relaxation curves for 1,6 are nonexponential and identical for 6 at spinning rates of 5, 10 and 12 kHz, dipolar relaxation via the paramagnetic centers is dominant. The relaxation data have been interpreted as a function of Mn2+ concentrations in terms of incorporation of the Mn2+ ions into the silica lattice when their concentration is small (,2.5 wt%). At higher concentrations, most of the manganese is located on the surface of the silica. Copyright © 2006 John Wiley & Sons, Ltd. [source] Relaxation times of choline, creatine and N -acetyl aspartate in human cerebral white matter at 1.5 TNMR IN BIOMEDICINE, Issue 3 2002D. R. Rutgers Abstract Several studies have investigated the T1 and T2 relaxation time of choline, creatine and N -acetyl aspartate in cerebral white matter in normal human subjects. However, these studies demonstrate a large variation in T1 and T2 values. In the present study, relaxation times of choline, creatine and N -acetyl aspartate were determined in cerebral white matter in 15 control subjects (age 21,±,2 y, mean,±,SD) at 1.5 T. Using PRESS, seven or eight data points were obtained to fit the T1 and T2 relaxation curves to, respectively. The mean voxel size was 14,cm3. The T1 relaxation times of choline, creatine and N -acetyl aspartate were 1091,±,132 (mean,±,SD), 1363,±,137 and 1276,±,132,ms. The T2 relaxation times were 352,±,52, 219,±,29 and 336,±,46,ms, respectively. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||