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Viscosity
Kinds of Viscosity Terms modified by Viscosity Selected AbstractsIMPACT OF BLENDING OF FRYING OILS ON VISCOSITY AND HEAT TRANSFER COEFFICIENT AT ELEVATED TEMPERATURESJOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2010SUKUMAR DEBNATH ABSTRACT In the present work, the effect of binary blending of five frying oils on kinematic viscosity (,) and convective heat transfer coefficient (h) was studied at elevated temperatures (170, 180 and 190C). A Cannon Ubbelhode calibrated capillary viscometer (Cannon Instrument Company, State College, PA) in a custom-designed and fabricated convective air bath heater and a highly conductive cylindrical metal transducer were used for generating,and h data, respectively. The value of,decreased from 3.617 × 10 - 6 to 2.062 × 10 - 6 m2 s - 1, and h increased from 221.0 to 301.2 Wm - 2 C - 1 by increasing the aforementioned oil temperatures. A good correlation between, (R2 > 0.996) or h (R2 > 0.987) of these frying oils and their selected binary blends with the previously mentioned temperature range was observed. Significant difference (P < 0.05) was found between different levels of parameters when treatments were compared using Tukey's test. PRACTICAL APPLICATIONS In food engineering applications, the physical properties of foods play an important role in the analysis of process parameters and in the design and fabrication of processing equipment. Determination of kinematic viscosity and convective heat transfer coefficients of frying oils and their selected blends at elevated temperatures are useful from an industrial point of view. In the present work, the effect of blending different edible oils on the kinematic viscosity and convective heat transfer coefficients at elevated temperatures was studied. Because selected blended oils provided lower levels of viscosities and higher levels of heat transfer coefficients, these results may be an attractive proposition in improving the quality of fried products and cost-effectiveness in the fried food industry. [source] VISCOSITY AND QUALITY OF TOMATO JUICE AS AFFECTED BY PROCESSING METHODSJOURNAL OF FOOD QUALITY, Issue 6 2007CHARANJIT KAUR ABSTRACT Quality and viscosity of tomato juice is strongly governed by mechanical and thermal abuse during processing. The effect of processing and storage duration on the viscosity and quality parameters of tomato juice was evaluated in the present work. Tomato juice was obtained by two different methods, normal method (NM) and variable method (VM), and was heated by both conventional and microwave hot break treatments. Tomato juice was evaluated for various quality characteristics including precipitate weight ratio, degree of serum separation (DOSS), Brookfield viscosity, lycopene levels, vitamin C, phenols and antioxidant activity. Changes observed in several quality parameters during storage were statistically insignificant. The methods and processing had the greatest contribution toward viscosity, whereas storage duration had no significant effects. Viscosity parameters viz precipitate weight, DOSS and Bostwick consistency revealed that juice processed by VM was more viscous than that of NM, irrespective of the hot break processing used. Ascorbic acid and lycopene content varied significantly with mechanical methods and processing conditions. However, phenolic content and antioxidant activity remained stable. The variable process represents an improvement over the conventional by enabling tomato processors to improve the consistency of the tomato product. PRACTICAL APPLICATIONS Quartering or slicing tomatoes followed by hot break processing techniques can significantly improve the quality of tomato juice in terms of reduced degree of serum separation and precipitate weight ratio. The modified technology could be considered as a viable and economical method for small- and medium-scale tomato processors with limited resources and facilities at their disposal. [source] DECREASE IN DYNAMIC VISCOSITY AND AVERAGE MOLECULAR WEIGHT OF ALGINATE FROM LAMINARIA DIGITATA DURING ALKALINE EXTRACTION,JOURNAL OF PHYCOLOGY, Issue 2 2008Peggy Vauchel Alginates are natural polysaccharides that are extracted from brown seaweeds and widely used for their rheological properties. The central step in the extraction protocol used in the alginate industry is the alkaline extraction, which requires several hours. In this study, a significant decrease in alginate dynamic viscosity was observed after 2 h of alkaline treatment. Intrinsic viscosity and average molecular weight of alginates from alkaline extractions 1,4 h in duration were determined, indicating depolymerization of alginates: average molecular weight decreased significantly during the extraction, falling by a factor of 5 between 1 and 4 h of extraction. These results suggested that reducing extraction time could enable preserving the rheological properties of the extracted alginates. [source] THE INFLUENCE OF SOLUTION VISCOSITY AND DIFFERENT VISCOSIFYING AGENTS ON APPLE JUICE FLAVORJOURNAL OF SENSORY STUDIES, Issue 3 2000SHANE WALKER ABSTRACT Viscosifying agents are used in foods as thickeners to produce improved mouthfeel and as stabilizers to prevent settling out of particulate matter. While viscosifying agents are also known to influence the sensory profile of the products in which they are used, previous studies have examined the effects of viscosifying agents at levels that are not typical of those used in foods. The current study used a descriptive analysis panel to examine the effects of both viscosity and viscosifying agent on the sensory properties of apple juice using three viscosifying agents (carboxymethylcellulose, xanthan and pectin) at levels of usage similar to those recommended for drink products. Gas chromatography-flame ionization detection and gas chromatography-mass spectrometry were conducted on the samples to relate alteration in physico-chemical parameters to changes in sensory profile. Results from the descriptive panel showed that increasing viscosity tended to decrease some aspects of flavor intensity (sourness and cooked apple odor). Individual viscosifying agents were shown to have specific effects on odor and flavor attributes, e.g. pectin enhanced cereal odor. Gas chromatography-flame ionization detection and mass spectrometry suggested that this effect was related to isopropyl alcohol contributed by the pectin in solution. Pectin also suppressed honey odor and flavor, lemon odor and cooked apple flavor. [source] ORAL SIZE PERCEPTION OF PARTICLES: EFFECT OF SIZE, TYPE, VISCOSITY AND METHODJOURNAL OF TEXTURE STUDIES, Issue 4 2005LINA ENGELEN ABSTRACT We investigated how different parameters affect oral size perception of small particles of SiO2 and polystyrene particles of varying sizes (2,230 ,m). Eighteen healthy subjects assessed the size of the particles by rubbing the sample between the tongue and the palate. The importance of size and type were studied by direct scaling and forced choice ranking and the results of the two methods were compared. To assess the relative importance of the tongue and the palate in oral size perception topical anesthesia was applied. The size and characteristics of particles are of importance for perception of particle size, where hard and irregular particles are perceived as larger than soft and round particles of similar size. The two methods of size perception, direct scaling and forced ranking produce very similar results on oral size perception. Topical anesthesia of either the tongue or the palate had no significant effect. [source] WATER ABSORPTION EFFECTS ON BIAXIAL EXTENSIONAL VISCOSITY OF WHEAT FLOUR DOUGHJOURNAL OF TEXTURE STUDIES, Issue 2 2003FERNANDO OSORIO ABSTRACT Biaxial extensional viscosities of wheat flour dough at three water absorption levels were determined as a function of biaxial strain rates using lubricated squeezing flow. The shape of the curves obtained in this study showed a sharp increase followed by a gradual increase which could indicate the presence of viscoelastic effects, which is not the usual case reported in the published literature for other products when using this technique. Plasticizing effect of water coupled with the effect of the starch and the interaction among the other components of wheat flour dough could explain the rheological behavior of flour dough during lubricated squeezing flow testing. Values of biaxial extensional viscosities of wheat flour dough for the three water absorption levels obtained in this study showed significant differences in the entire deformation range (P < 0.05). [source] INTERNATIONAL INTER-LABORATORY TRIALS TO DETERMINE THE FACTORS AFFECTING THE MEASUREMENT OF CHOCOLATE VISCOSITYJOURNAL OF TEXTURE STUDIES, Issue 5 2000J.-M. AESCHLIMANN The working group of the International Office of Cocoa, Chocolate and Sugar Confectionery (IOCCC) performed a sequence of five ring tests to improve the agreement of the standard method for measuring viscosity of chocolate between laboratories. Reporting shear stress measurements instead of using the Casson equation improved the agreement, as did standardising the method of cleaning the concentric cylinder and calibrating the viscometers. In the revised method, the standard deviation for shear stress measurement at shear rates greater than 5 s,1 from 23 laboratories was less than 8%. However, the Casson yield values had a seven-fold range and the Casson plastic viscosity a two-fold range, which was unacceptably high. A new method (IOCCC 2000) has been published as a result of this work and is available from CAOBISCO in Bruxelles, Belgium. [source] VISCOUS PROPERTIES OF TARO FLOUR EXTRUDED WITH WHEY PROTEINS TO SIMULATE WEANING FOODS,JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 3 2002C. I. ONWULATA Taro flour, derived from the corm of Colocasia Esculenta cv. Lehua, a root tuber grown in the tropical regions of the world, was extruded with whey protein concentrate (WPC), whey protein isolate (WPI) or lactalbumin (LAC), to derive blends containing 20% protein, simulating the protein content of some weaning foods. Taro flour is unique because of its extremely small particle size (1,5 micron) and high mucilage or gum content, making it a possible replacement for corn or wheat starch in weaning foods. Extrusion processing temperatures were from 100 to 130C and moisture of the feed blends was held constant at 18%. The extrudates were pulverized, made into powders, and rehydrated to make a paste. Viscosities of the feed blends before extrusion and the pastes made from the extrudates were determined using a Rapid Visco Analyzer (RVA) to determine peak, final, and breakdown viscosities. Water solubility and absorption indices were also determined. Extrudates made from taro containing whey products expanded more than taro alone; were easier to grind into powders; and rehydrated readily in water to form pastes. Before extrusion, the peak viscosities of the blends were 5000, 2600, 1600, 1600 cP for taro flour, taro with WPI, taro with WPC, or taro with LAC, respectively. After extrusion cooking, the viscosities for taro flour, taro with WPI, taro with WPC, or taro with LAC were 110, 65, 70 or 90 cP, respectively. Taro extrudates without protein absorbed the most water, and were more soluble than products containing whey proteins or LAC. The addition of whey proteins reduced peak viscosities, but WPI and taro pastes were characteristic of weaning foods. Both extrusion cooking and the [source] Coarse-Grained Simulations of Elongational Viscosities, Superposition Rheology and Shear Banding in Model Core,Shell SystemsMACROMOLECULAR THEORY AND SIMULATIONS, Issue 8 2007A. van den Noort Abstract A recently developed coarse-grain model is used to investigate nonlinear rheological properties of model core,shell systems. The influence of several model parameters on the stresses and shear rates is investigated. Continuous planar elongational flow and superposition rheology are studied and compared to simple shear flow results. With particular values of the model parameters, an initially linear velocity profile splits into many bands with different shear rates and different densities, which finally merge into just two bands stacked along the gradient direction. With the box sizes used in our simulations, stick and Lees,Edwards boundary conditions lead to qualitatively similar results, with the stick boundary simulations showing better quantitative agreement with experiments. [source] Surface Tension and Viscosity of the Ni-based Superalloy CMSX-4 Measured by the Oscillating Drop Method in Parabolic Flight Experiments,ADVANCED ENGINEERING MATERIALS, Issue 5 2007K. Higuchi The surface tension and the viscosity of the Ni-based superalloy CMSX-4 were measured by the oscillating drop method on electromagnetically levitated specimen under reduced gravity conditions on a parabolic flight. The twenty seconds of reduced gravity available in a single parabola proved sufficient for melting, heating into the stable liquid and free cooling to solidification. [source] Effects of somatic cell counts on the physicochemical and rheological properties of yoghurt made from sheep's milkINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2010Masoud Najaf Najafi Summary In the present work, yoghurts were made from sheep's milk with two different somatic cell count (SCC), at low (200 000 cells mL,1) and high (750 000 cells mL,1) levels. The characteristics of the final product were analysed for pH, acidity, protein, total solids, fat, syneresis, water holding capacity (WHC) and apparent viscosity. Samples were analysed on days 1, 7 and 14 after production of yoghurts. The SCC had no significant effect either on the acidity or pH of the yoghurt at 24 h (P > 0.05) but a significant effect (P < 0.05) was observed at 168 h. No effects of SCC were observed on total solids and fat content of the yoghurt after 24 and 168 h. High SCC (HSCC) yoghurt had higher protein content (P < 0.05). The yoghurt with the highest SCC had the highest level of syneresis. Viscosity of HSCC yoghurt was higher than that of the low SCC yoghurt on days 1, 7 and 14 of storage. The flow properties also showed that the low SCC yoghurt was softer than that from milk with high content in somatic cells. [source] Food Texture and Viscosity: Concept and MeasurementINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2003John Mitchell No abstract is available for this article. [source] Effect of silica on viscosity, tack, and shear strength of epoxidized natural rubber-based pressure-sensitive adhesives in the presence of coumarone-indene resinJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Imran Khan Abstract The viscosity, loop tack, and shear strength of silica-filled epoxidized natural rubber (ENR 25 and ENR 50 grade) adhesive were investigated using coumarone-indene as the tackifying resin. Silica loading was varied from 10,50 parts per hundred parts of rubber (phr), whereas the coumarone-indene concentration was fixed at 40 phr. Toluene was used as the solvent throughout the study. Polyethylene terephthalate substrate was coated at various adhesive coating thicknesses, i.e., 30, 60, 90, and 120 ,m using a SHEEN Hand Coater. Viscosity of the adhesive was determined by a HAAKE Rotary Viscometer whereas loop tack and shear strength were measured by a Llyod Adhesion Tester operating at 30 cm/min. Result shows that viscosity of the adhesive increases gradually with increase of silica loading due to the concentration effect of the filler. Both loop tack and shear strength show maximum value at 40 phr silica for ENR 25. However, the respective values for ENR 50 are 20 and 40 phr of filler. This observation is attributed to the maximum wettability and compatibility of adhesive on the substrate at the respective silica loadings. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] The effect of viscosity on surface tension measurements by the drop weight methodJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007T. Kaully Abstract Viscosity is one of the parameters affecting the measured surface tension, as fluid mechanics affects the measurement process using conventional methods. Several methods including the selected planes (SPM) and WDSM which combines the weight drop method (WDM) and SPM, are applied to surface tension measurement of high viscous liquids. Yet, none of them treats the viscosity effect separately. The current publication presents a simple, easy to apply empirical approach of satisfactory accuracy, for evaluation of surface tension of liquids having wide range of viscosities up to 10 Pa s. The proposed method is based on Tate's law and the "drop weight" method using calibration curves of known liquids having similar surface tensions but different viscosities. Drop weight of liquids having viscosity ,0.05 Pa s, was found to be significantly affected by the liquid viscosity. The shape factor, f, of high viscosity liquids was found to correlate linearly with the logarithm of viscosity, pointing the importance of viscosity correction. The experimental correlation presented in the current work can be used as a tool for the evaluation of surface tension for high viscosity liquids such as prepolymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] COATING WITH HONEY: A STUDY WITH MODEL SOLIDSJOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2002BHAVESH K. PATEL ABSTRACT Simulation studies on coating of steel balls with honey as well as the rheological measurements were carried out at different moisture contents (20.3,37.7%, dry basis), and temperatures (5,80C). The coating characteristics of honey were judged by the thickness of honey layer, and by the proposed index, dimensionless uptake. Honey possesses extremely high viscosity at low temperatures and/or at low moisture contents. The sensitivity of honey viscosity with temperature was determined by using Arrhenius equation. Enhanced values of dimensionless uptake and thickness were obtained at low temperature-low moisture combinations. Viscosity of honey for easy handling and coating is in the neighborhood of 103 mPas corresponding to a temperature of 50C. [source] Perceived Creaminess and Viscosity of Aggregated Particles of Casein Micelles and ,-CarrageenanJOURNAL OF FOOD SCIENCE, Issue 5 2010Kelly L. Flett Abstract:, Creaminess, in terms of sensory science, is a very complex and multifaceted term. It is a descriptor often reserved for fat-containing dairy emulsions, however, has also been used to describe nondairy food emulsions. In the food industry, it is a great challenge to decrease fat content while maintaining the original quality and sensory characteristics of a food product. An aggregated particle consisting of casein micelles and ,-carrageenan has the potential to enhance the perceived creaminess of a low-fat food product, due to its colloidal size. In this study, these aggregates were incorporated into nonfat dairy beverages and subjected to sensory studies. In the 1st sensory study, the aggregates, either as a powdered ingredient or a fresh ingredient, were added to thickened dairy beverages and compared to similar beverages containing skim milk powder and either no fat or 2% dairy fat. The panelists found the aggregate-containing beverages to be creamier and more viscous in comparison to the control beverages. In the 2nd sensory study, fresh and powdered aggregates, at 2 concentrations, were added to a sweetened nonfat dairy beverage and compared to a similar beverage containing 2% dairy fat. The results of this panel showed that aggregates, especially at increased concentrations, were perceived as more creamy than the fat-containing beverage. Panelists described the creaminess of the aggregates as more thick and viscous while the dairy fat was described more in terms of mouth-coating. Thus, we have developed a nonfat milk ingredient that can contribute creaminess to a food product. Practical Application:, This study shows potential applications of aggregates of casein micelles and ,-carrageenan as a fat-mimetic or creaminess-enhancing ingredient. These particles may be produced as either fresh aggregates directly formed in a dairy product or as powdered aggregates added to dairy or nondairy products. [source] Effect of Components Extracted from Okara on the Physicochemical Properties of Soymilk and Tofu TextureJOURNAL OF FOOD SCIENCE, Issue 2 2007Kyoko Toda ABSTRACT:, The physicochemical properties of soymilk and the texture of tofu were compared with regard to 2 kinds of soymilk, one of which was prepared by squeezing homogenates before heating and the other was prepared by squeezing after heating raw soymilk with okara, residue of soymilk production. Relative particulate protein content and viscosity were higher and pH was lower in the soymilk prepared by the latter method, in which liberated lipid bodies were decreased and more lipids were precipitated with protein after centrifugation, suggesting a change in the interaction between proteins and lipids. A difference in the distribution of proteins and lipids was also implied by analysis with a laser particle size analyzer. The breaking stress of tofu made with 0.30% glucono-delta-lactone increased in accordance with an increase in particulate protein. The calcium and magnesium contents increased in soymilk prepared by squeezing after heating with okara. Viscosity was slightly increased and pH decreased by adding calcium to the soymilk, but the particulate protein content and breaking stress of tofu did not increase significantly. To examine the effect of macromolecules, okara was extracted by boiling and dialyzed. Viscosity and particulate protein content in soymilk increased as the dialyzed extracts of the okara were added. The breaking stress of tofu was increased by adding the dialyzed extracts but excessive amounts of the extracts resulted in softer tofu. Spectra of Fourier-transform infrared spectroscopy and electrophoresis-separated patterns of proteins indicated that the dialyzed extracts contained mainly polysaccharides and the Basic 7S globulin protein. [source] Functional Properties of Improved Glycinin and ,-nglycinin FractionsJOURNAL OF FOOD SCIENCE, Issue 4 2004D. A. Rickert ABSTRACT: Glycinin and ,-conglycinin have unique functionality characteristics that contribute important properties in soy foods and soy ingredients. Limited functionality data have been published for glycinin and ,-conglycinin fractions produced in pilot-scale quantities. Protein extraction conditions were previously optimized for our pilotscale fractionation process to maximize protein solubilization and subsequent product recovery. Glycinin, ,-conglycinin, and intermediate (mixture of glycinin and ,-conglycinin) fractions were prepared using optimized-process (OP) extraction conditions (10:1 water-to-flake ratio, 45°C) and previous conditions termed Wu process (WP) (15:1, 20°C). Viscosity, solubility, gelling, foaming, emulsification capacity, and emulsification activity and stability of the fractionated proteins, and soy protein isolate (SPI) produced from the same defatted soy white flakes were compared to evaluate functional properties of these different protein fractions. Differential scanning calorimetry, sodium dodecylsulfate-polyacrylamide gel electrophoresis, and surface hydrophobicity data were used to interpret functionality differences. OP ,-conglycinin had more glycinin contamination than did the WP ,-conglycinin. OP and WP solubility profiles were each similar for respective glycinin and ,-conglycinin fractions. Emulsification activities and stabilities were higher for OP ,-conglycinin and OP intermediate fractions compared with respective WP fractions. ,-Conglycinin and SPI emulsification capacities (ECs) mirrored solubility profile, whereas glycinin ECs did not. OP glycinin had a higher foaming capacity than WP glycinin. OP and WP intermediate fraction apparent viscosities trended higher than those of other protein fractions. ,-Conglycinin dispersions at pH 3 and 7 produced firm gels at 80°C, whereas glycinin dispersions formed weaker gels at 99°C and did not gel at 80°C. [source] DTG thermal analyses and viscosity measurements of three commercial agar impression materialsJOURNAL OF ORAL REHABILITATION, Issue 7 2002M. Taira Three commercial agar impression materials, two for clinical uses and one for dental laboratory, were examined for their thermal properties by differential thermogravimetric (DTG) thermal analyses and viscosity measurements. On DTG profiles, an endothermic peak along with weight loss at around 100 °C was observed on all three agar impression materials as a result of water evaporation. Two clinical agar impression materials were more susceptible to this trend than the remaining one dental laboratory agar impression material. The viscosity of three agar impression materials could be expressed in the exponential function of temperature. Viscosity at 46 °C of one dental laboratory agar impression material far exceeded those of two clinical agar impression materials. Monitoring the viscosity could facilitate the detailed analysis of setting process of agar impression materials upon cooling, and might be useful for future development of agar-based dental impression materials. [source] Measurement of Viscosity of Densifying Glass-Based Systems by Isothermal Cyclic Loading DilatometryJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2004Aravind Mohanram This study describes the isothermal cyclic loading dilatometry (ICLD) technique to measure the viscosity of glass-based materials. We demonstrate its merit relative to constant-load techniques in minimizing the stress history effects (changes in shrinkage anisotropy and sample microstructure) that arise due to the application of an external load. A constant-load test overestimates the viscosity by an order of magnitude compared with a cyclic load test. To obtain accurate viscosity data, maximum loading rates and longer unloading periods are desirable as they reduce effects of shrinkage anisotropy on viscosity values. Representative data for a low-temperature cofired ceramic (LTCC) material are reported. Nonparametric statistical tests revealed insignificant differences between the viscosity data sets at 5% significance level and thus indicate good reproducibility of the testing methodology. [source] Density, Surface Tension, and Viscosity of PbO-B2O3 -SiO2 Glass MeltsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2004Shigeru Fujino The density, surface tension, and viscosity of the melts from the PbO-B2O3 -SiO2 system have been measured at temperatures in the range 1073,1473 K. The effect of composition on these properties was also investigated. The density of the melt was found to increase linearly with increasing PbO content. Molar volume was derived from the density data, and its deviation from the additivity of partial molar volumes was calculated. These deviations in molar volume from those obtained from additivity rules have been used along with the ratio of various coordination numbers of boron (as reported by Bray) to discuss the structure of the melts. The surface tension was found to decrease with decreasing SiO2/B2O3 ratio, and to increase in the range of the PbO content between 30 and 60 mol%, showing a maximum at ,60 mol% PbO, and then decreased with further additions. This result suggested that the surface tension would be affected primarily by the B2O3 content in the range of the PbO content between 30,60 mol%, and mainly by the PbO content in the range of the PbO content >60 mol%, respectively. The viscosity of the melt was found to decrease linearly with increasing PbO content. The results obtained indicate that the increase in viscosity with B2O3 was half that of SiO2 (on a molar basis), and an empirical equation has been proposed for the viscosity as a function of mole fraction. [source] Local Viscosity of Si-O-C-N Nanoscale Amorphous Phases at Ceramic Grain BoundariesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2001Giuseppe Pezzotti Internal friction characterization has been used to quantitatively assess the viscosity characteristics of Si-O-C-N glasses segregated to nanometer-sized grain boundaries of polycrystalline Si3N4 and SiC ceramics. A relaxation peak of internal friction, which arises with rising temperature from the viscous sliding of glassy grain boundaries, was systematically collected and analyzed with respect to its shift upon changing the oscillation frequency. As a result of such an analysis, both activation energy for viscous grain-boundary flow and inherent viscosity of the intergranular glass film could be quantitatively evaluated. Two main features are shown: (i) the presence of N and/or C greatly affects the viscosity characteristics of SiO2 phases at Si3N4 and SiC grain boundaries; and (ii) the internal friction method has potential as a unique experimental tool for understanding the local properties of nanoscale amorphous phases in new ceramic materials. [source] Grain-Boundary Viscosity of Preoxidized and Nitrogen-Annealed Silicon CarbidesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2001Giuseppe Pezzotti Internal friction experiments were conducted on a model SiC polycrystal prepared from preoxidized (high-purity) SiC powder. This material contained high-purity SiO2 glass at grain boundaries in addition to a free-carbon phase, which was completely removed upon powder preoxidation. Comparative tests were conducted on a SiC polycrystal, obtained from the as-received SiC powder with the addition of 2.5 vol% of high-purity SiO2. This latter SiC material was also investigated after annealing at 1900°C for 3 h in a nitrogen atmosphere. Electron microscopy observations revealed a glass-wetted interface structure in SiC polycrystals prepared from both as-received and preoxidized powders. However, the former material also showed a large fraction of interfaces coated by turbostratic graphite. Upon high-temperature annealing in nitrogen, partial glass dewetting occurred, and voids were systematically observed at multigrain junctions. The actual presence of nitrogen could only be detected in a limited number of wetted interfaces. A common feature in the internal friction behavior of the preoxidized, SiO2 -added and nitrogen-annealed SiC was a relaxation peak that resulted from grain-boundary sliding. Frequency-shift analysis revealed markedly different characteristics for this peak: both the magnitude of the intergranular glass viscosity and the activation energy for grain-boundary viscous flow were much higher in the nitrogen-annealed material. Results of torsional creep tests were consistent with these findings, with nitrogen-annealed SiC being the most creep resistant among the tested materials. [source] Grain-Boundary Viscosity of BaO-Doped SiCJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2000Giuseppe Pezzotti Internal friction characterization of the viscosity of a residual SiO2/BaO glass, segregated to grain boundaries of polycrystalline SiC, is presented. The anelastic relaxation peak of internal friction, arising from viscous slip along grain boundaries wetted by a glass phase, is analyzed. Two SiC polycrystals, containing SiO2/BaO glasses with different compositions, are studied and compared with a SiC polycrystal containing only pure SiO2. The internal friction peak is first analyzed with respect to its shift upon frequency change. This analysis allows quantitative assessment of both the intrinsic viscosity and the activation energy for viscous flow of the grain-boundary phase. Both parameters markedly decrease with increasing amounts of BaO dopant, which is consistent with data reported in the literature on SiO2 and SiO2/BaO bulk glasses with the same nominal composition. Analysis of the peak morphology is also attempted, considering the evolution of peak width while varying the grain-boundary glass composition. Moreover, the role of microstructural parameters, such as the distributions of grain size and grain-boundary angles, on the broadening of the internal friction peak is addressed, and a procedure is proposed that allows quantitative evaluation of the activation energy for viscous flow of intergranular glass merely from the width of the internal friction peak. [source] Viscosity and starch particle size effects on rehydration of freeze-dried carrots Alejandro Marabi and I Sam Saguy.JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2005706 (2005), Agriculture85(4):700, Journal of the Science of Food The original article to which this Erratum refers was published in Journal of the Science of Food and Agriculture 85(4):700,706 (2005). Copyright © 2005 Society of Chemical Industry [source] Viscosity and emulsifying capacity in pota and octopus muscle during frozen storageJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2003C Ruiz-Capillas Abstract The functional quality of pota and octopus muscle during frozen storage for up to 12 months was evaluated periodically by determining viscosity and emulsifying capacity levels. In both species the effect on different anatomical locations (mantle and arms) in mature and young male and female individuals was studied. Apparent viscosity and emulsifying capacity levels were greater in octopus than in pota. While in pota a sharp decrease was observed in viscosity levels, falling to virtually nil, viscosity levels in octopus increased in the first 2 months and only slight decreases were observed at the end of storage. The change in emulsifying capacity, however, was quite similar in the two species, with not very sharp decreases. According to these results, emulsifying capacity measurement could be a suitable technique for showing the changes that occur in the muscle proteins of these species when they are stored frozen. No differences were observed by sex, but there were differences depending on the stage of maturity and anatomical location. Thus pota and octopus mantles present greater stability in frozen storage than the arms, and there is a tendency, although not always significant, that the mantles of young pota and octopus specimens are more stable in frozen storage than the mantles of adult individuals. Copyright © 2003 Society of Chemical Industry [source] Microwave and Ionic Liquids: Inverse Temperature Dependence of Viscosity in Aqueous Medium of Grafted CopolymersMACROMOLECULAR REACTION ENGINEERING, Issue 9 2009Ella Bezdushna Abstract We elaborated a route to the thermosensitive polyelectrolyte system composed of 1-methyl-3-vinylimidazolium salt with , -cyclodextrin complexed counterions and mono-(meth)acrylic functionalized poly(N -isopropylacrylamide) as grafted side chains via a three-step synthetic procedure. The aqueous solution of the polyelectrolyte displays partially inverse thermoresponsive behavior; it exhibits enhancement of shear viscosity up to body temperature. Furthermore, based on classically prepared poly(NIPAAm) bearing terminal amino groups, corresponding (meth-) acrylamide-type of macromonomers were easily obtained under microwave conditions. [source] Influence of filler type and content on properties of styrene-butadiene rubber (SBR) compound reinforced with carbon black or silicaPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2004Sung-Seen Choi Abstract Rubber compounds are filled with reinforcing fillers to improve their physical properties. Carbon black and silica have different surface chemistries to each other. Differences in properties of carbon black- and silica-reinforced styrene-butadiene rubber (SBR) compounds were studied. Variation of properties of carbon black- or silica-filled compounds with the filler content was also investigated. The silica-filled compounds without any coupling agent and dispering agent were prepared to investigate the influence of polar materials-adsorption on the silica surface. Viscosity and crosslink density increased with increase of the filler content. Hardness, modulus, tensile strength, and wear property were improved more and more by increasing the filler content. Viscosity of the silica-filled compound was higher than that of the carbon black-filled one. Cure rate of the silica-filled compound became slower as the filler content increased, while that of the carbon black-filled one became faster. Difference in properties between the carbon black- and silica-filled compounds were explained by the poor silica dispersion and the adsorption of cure accelerator on the silica surface. Copyright © 2004 John Wiley & Sons, Ltd. [source] Synthesis and characterization of some novel silicon esters and their application as lubricant base stock solutionAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 12 2009Kanak Saxena Abstract A series of functional organosilanes and their esters were synthesized by the hydrosilylation reaction of SiH group-bearing organosilicon derivatives with maleic anhydride using Speier's catalyst and their esterification with long-chain alcohols in the presence of stannous oxide. These products have been characterized using elemental analysis, FT-IR, 1H, 13C and 29Si NMR. Viscosity, density, pour point, flash point and tribological properties of these compounds have also been evaluated. These esters have a pour point of <,60 °C, a flash point of ,200 °C (closed-cup) and excellent load carrying capacity. Copyright © 2009 John Wiley & Sons, Ltd. [source] Enzymatic Hydrolysis of Waste Office Paper Using Viscosity as Operating ParameterBIOTECHNOLOGY PROGRESS, Issue 2 2001Enoch Y. Park Enzymatic hydrolysis of waste office (WO) paper with feeding WO paper in a reactor was investigated using apparent viscosity as operating parameter. Since the apparent viscosity was correlated with the concentration of pulping WO paper, the amount of hydrolyzed WO paper was assumed by measuring the decrease in the apparent viscosity. Then the amount of hydrolysis WO paper and the amount of enzyme corresponding to the desired ratio were fed into the reactor. When the WO paper and 1% (to the amount of WO paper) enzyme were fed to the hydrolytic reaction, 87 g/L of reducing sugar (RS) with a hydrolytic yield of 42.2% was obtained for a 24-h hydrolysis. However, when nonpulping WO paper and 5% (to the amount of WO paper) enzyme were fed to the hydrolytic reaction, 120 g/L of RS with a hydrolytic yield of 40% was obtained for a 24-h hydrolysis. Therefore, the RS concentration from this hydrolysis process feeding WO paper using apparent viscosity as operating parameter may be of sufficient concentration to serve as a carbon source in microorganism culture or chemical feedstock. [source] | ||||||||||||||||||||||||||||||||||||||||||||||