The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Ganesan Narsimhan - One of the best experts on this subject based on the ideXlab platform.
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Stability of thin emulsion film between two oil phases with a viscoelastic liquid-liquid interface.
Journal of Colloid and Interface Science, 2008Co-Authors: Ganesan NarsimhanAbstract:Abstract The viscoelastic properties of adsorbed protein layer in food emulsions and foams are important in providing stability to such systems. Linear stability analysis for a protein stabilized aqueous film sandwiched between two semi-infinite oil phases with a viscoelastic liquid–liquid interface is presented. The interfacial dilatational and shear viscoelastic properties are described by Maxwell models. The aqueous film is found to be more stable for smaller values of dilatational (shear) relaxation times and larger values of interfacial dilatational (shear) viscosities. The asymptotic values of maximum Growth Coefficient for very large and very small values of interfacial dilatational (shear) viscosities were found to be independent of relaxation times and correspond to those for immobile and fully mobile liquid–liquid interfaces respectively. The aqueous film is shown to be more stable for larger viscosities of the oil phase with the maximum Growth Coefficient approaching zero as the ratio of viscosities of oil and aqueous phases approach very large values and an asymptotic value corresponding to that for a foam film for very small viscosity ratios.
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stability of thin stagnant film on a solid surface with a viscoelastic air liquid interface
Journal of Colloid and Interface Science, 2005Co-Authors: Ganesan Narsimhan, Zebin WangAbstract:Abstract Linear stability analysis for a film on a solid surface with a viscoelastic air–liquid interface is presented. The interfacial dilatational and shear viscoelastic properties were described by Maxwell models. Dilatational and shear interfacial elasticity and viscosity were shown to improve film stability. When the interfacial rheological properties are extremely large or small, the maximum perturbation Growth Coefficient is shown to reduce to those for immobile and mobile interfaces respectively. Calculated values of maximum Growth Coefficient for thin film stabilized by 0.5% β-lactoglobulin approached those of mobile films for thick ( > 2000 nm ) and those for immobile films for thin ( 100 nm ) films respectively with the values lying between the two limits for intermediate film thicknesses.
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Stability of thin stagnant film on a solid surface with a viscoelastic air–liquid interface
Journal of colloid and interface science, 2005Co-Authors: Ganesan Narsimhan, Zebin WangAbstract:Abstract Linear stability analysis for a film on a solid surface with a viscoelastic air–liquid interface is presented. The interfacial dilatational and shear viscoelastic properties were described by Maxwell models. Dilatational and shear interfacial elasticity and viscosity were shown to improve film stability. When the interfacial rheological properties are extremely large or small, the maximum perturbation Growth Coefficient is shown to reduce to those for immobile and mobile interfaces respectively. Calculated values of maximum Growth Coefficient for thin film stabilized by 0.5% β-lactoglobulin approached those of mobile films for thick ( > 2000 nm ) and those for immobile films for thin ( 100 nm ) films respectively with the values lying between the two limits for intermediate film thicknesses.
Zebin Wang - One of the best experts on this subject based on the ideXlab platform.
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stability of thin stagnant film on a solid surface with a viscoelastic air liquid interface
Journal of Colloid and Interface Science, 2005Co-Authors: Ganesan Narsimhan, Zebin WangAbstract:Abstract Linear stability analysis for a film on a solid surface with a viscoelastic air–liquid interface is presented. The interfacial dilatational and shear viscoelastic properties were described by Maxwell models. Dilatational and shear interfacial elasticity and viscosity were shown to improve film stability. When the interfacial rheological properties are extremely large or small, the maximum perturbation Growth Coefficient is shown to reduce to those for immobile and mobile interfaces respectively. Calculated values of maximum Growth Coefficient for thin film stabilized by 0.5% β-lactoglobulin approached those of mobile films for thick ( > 2000 nm ) and those for immobile films for thin ( 100 nm ) films respectively with the values lying between the two limits for intermediate film thicknesses.
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Stability of thin stagnant film on a solid surface with a viscoelastic air–liquid interface
Journal of colloid and interface science, 2005Co-Authors: Ganesan Narsimhan, Zebin WangAbstract:Abstract Linear stability analysis for a film on a solid surface with a viscoelastic air–liquid interface is presented. The interfacial dilatational and shear viscoelastic properties were described by Maxwell models. Dilatational and shear interfacial elasticity and viscosity were shown to improve film stability. When the interfacial rheological properties are extremely large or small, the maximum perturbation Growth Coefficient is shown to reduce to those for immobile and mobile interfaces respectively. Calculated values of maximum Growth Coefficient for thin film stabilized by 0.5% β-lactoglobulin approached those of mobile films for thick ( > 2000 nm ) and those for immobile films for thin ( 100 nm ) films respectively with the values lying between the two limits for intermediate film thicknesses.
M. Jover - One of the best experts on this subject based on the ideXlab platform.
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a proposal for modelling the thermal unit Growth Coefficient and feed conversion ratio as functions of feeding rate for gilthead sea bream sparus aurata l in summer conditions
Aquaculture Research, 2013Co-Authors: Ignacio Jauralde, Ana Tomás, Rodolfo Ballestrazzi, Silvia Martinezllorens, M. JoverAbstract:Modelling Growth as a function of feeding rate (FR) could be one of the most important tools for fish farms, because this knowledge allows Growth to be maximized, or the feed conversion ratio (FCR) to be minimized, thereby improving profits. All Growth models should include the three principal variables involved in Growth: initial body weight, temperature and feeding rate. The thermal-unit Growth Coefficient (TGC) already includes water temperature variation and initial body weight. Studying variation in TGC for fish fed the same diet, but at several feeding rates provides interesting information for modelling. Six different trials were conducted where gilthead sea bream of several different initial weights (24, 38, 50, 110, 220 or 289 g) were fed increasing amounts, and Growth and the conversion index response were measured. The TGC response was modelled as a function of FR, and both asymptotic and quadratic responses were examined. The asymptotic model, TGC × 1000 = 2.037*(1−e (−0.8*(FR−0.22)), had an adjusted R2 value of 96.18, whereas the quadratic model, TGC × 1000 = −0.381 + 1,715 × FR−0,382 × FR2, had an adjusted R2 value of 96.42. Simulations of the FCR and the economical profitability index (EPI) were conducted to provide tools for maximizing efficiency and profitability, and the results suggest that these tools will be useful for future investigations.
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A two-stage Growth model for gilthead sea bream (Sparus aurata) based on the thermal Growth Coefficient
Aquaculture, 2012Co-Authors: P. Mayer, V.d. Estruch, M. JoverAbstract:Abstract Several authors have proposed models to describe fish Growth taking the influence of temperature into account, and one of the most interesting is the “thermal unit Growth Coefficient” ( TGC ). Recent research has demonstrated that TGC varies throughout the Growth cycle of fish, making it necessary to establish different stanzas. In this work, the original TGC model using 1/3 as an exponent was compared with a new model considering 2/3. Likewise, two stages for the Growth of gilthead sea bream under commercial conditions in marine farms were detected by means of TGC seasonal models using the continuous temperature curve. A critical value for weight around 117 g was obtained, which could mark the transition between two Growth dynamics. To describe the weight evolution during a complete production cycle, the two Growth stages were described by two separate seasonal TGC models (1/3- TGC model and 2/3- TGC model), and with an integrated model named the Mixed- TGC model, which presents interesting properties of continuity and differentiability and could be an important tool for fish farm management.
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A two-stage Growth model for gilthead sea bream (Sparus aurata) based on the thermal Growth Coefficient
Aquaculture, 2012Co-Authors: P. Mayer, V.d. Estruch, M. JoverAbstract:Several authors have proposed models to describe fish Growth taking the influence of temperature into account, and one of the most interesting is the "thermal unit Growth Coefficient" (TGC). Recent research has demonstrated that TGC varies throughout the Growth cycle of fish, making it necessary to establish different stanzas. In this work, the original TGC model using 1/3 as an exponent was compared with a new model considering 2/3. Likewise, two stages for the Growth of gilthead sea bream under commercial conditions in marine farms were detected by means of TGC seasonal models using the continuous temperature curve. A critical value for weight around 117g was obtained, which could mark the transition between two Growth dynamics. To describe the weight evolution during a complete production cycle, the two Growth stages were described by two separate seasonal TGC models (1/3-TGC model and 2/3-TGC model), and with an integrated model named the Mixed-TGC model, which presents interesting properties of continuity and differentiability and could be an important tool for fish farm management.V.D. Estruch and M. Jover were partially supported by the Universitat Politecnica de Valencia, PAID 2009-2010.Mayer, P.; Estruch Fuster, VD.; Jover Cerda, M. (2012). A two-stage Growth model for gilthead sea bream (Sparus aurata) based on the thermal Growth Coefficient. Aquaculture. 358-359:6-13. doi:10.1016/j.aquaculture.2012.06.016S613358-35
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A proposal for modelling the thermal‐unit Growth Coefficient and feed conversion ratio as functions of feeding rate for gilthead sea bream (Sparus aurata, L.) in summer conditions
Aquaculture Research, 2011Co-Authors: Ignacio Jauralde, Silvia Martínez-llorens, Ana Tomás, Rodolfo Ballestrazzi, M. JoverAbstract:Modelling Growth as a function of feeding rate (FR) could be one of the most important tools for fish farms, because this knowledge allows Growth to be maximized, or the feed conversion ratio (FCR) to be minimized, thereby improving profits. All Growth models should include the three principal variables involved in Growth: initial body weight, temperature and feeding rate. The thermal-unit Growth Coefficient (TGC) already includes water temperature variation and initial body weight. Studying variation in TGC for fish fed the same diet, but at several feeding rates provides interesting information for modelling. Six different trials were conducted where gilthead sea bream of several different initial weights (24, 38, 50, 110, 220 or 289 g) were fed increasing amounts, and Growth and the conversion index response were measured. The TGC response was modelled as a function of FR, and both asymptotic and quadratic responses were examined. The asymptotic model, TGC × 1000 = 2.037*(1−e (−0.8*(FR−0.22)), had an adjusted R2 value of 96.18, whereas the quadratic model, TGC × 1000 = −0.381 + 1,715 × FR−0,382 × FR2, had an adjusted R2 value of 96.42. Simulations of the FCR and the economical profitability index (EPI) were conducted to provide tools for maximizing efficiency and profitability, and the results suggest that these tools will be useful for future investigations.
Dominique P Bureau - One of the best experts on this subject based on the ideXlab platform.
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evidence of three Growth stanzas in rainbow trout oncorhynchus mykiss across life stages and adaptation of the thermal unit Growth Coefficient
Aquaculture, 2007Co-Authors: Andre Dumas, Dominique P BureauAbstract:Current mathematical Growth models describe the Growth of finfish with few considerations of the changes in Growth pattern occurring across life stages. This study analysed the Growth pattern of rainbow trout and tried to improve the goodness of fit of an empirical Growth function. Growth data were obtained from 21 separate lots of rainbow trout (Ontario ARSTstrain) fed to satiation and reared at constant water temperature (8.5 °C) at the Alma Aquaculture Research Station, University of Guelph between 1997 and 2005. Growthrates(207observations)werecalculatedusingthethermal-unitGrowthCoefficient(TGC).CalculatedGrowthrateswereregressed againstlive body weight (BW). Piecewiselinear analysis was used to determine changes in the Growth pattern. This analysis revealed the existence of three Growth stanzas: from first-feeding (0.2 g) to 20 g (Stanza 1); from 20 to 500 g (Stanza 2); and N500 g (Stanza 3). The least squares method was used to optimize the weight exponent within each Growth stanza and to improve the goodness of fit of the TGC model.Resultsindicatedthatweightexponentsotherthan1 −b=1/3currentlyusedintheTGCmodelshouldbeusedforStanzas1and3. OnlytheweightexponentforStanza2wasnotsignificantlydifferentfromtheconventionalTGCmodelwhere1 −b=1/3(P ≥0.05).The weightexponentvaluesthatgavethebestfitwithinStanzas1and3were0.209and0.967,respectively.ThepredictedvaluesforBWwere overestimated for small fish (b20 g) and underestimated for large fish (N500 g) when using the exponent 1/3. The similarity between predictedandobservedBWforfishweighingbetween20–500gmeantthatthecuberootofBWissuitableforpredictingBWinStanza2. These results provide a more realistic Growth function that better fits the Growth pattern observed across the life stages of rainbow trout. © 2007 Elsevier B.V. All rights reserved.
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development of bioenergetic models and the fish prfeq software to estimate production feeding ration and waste output in aquaculture
Aquatic Living Resources, 1998Co-Authors: Young C Cho, Dominique P BureauAbstract:Feeding guides for salmonid fishes have been available from various sources for many years. These feeding guides have originated in one way or another from earlier feeding charts of the 1950-60s when meal-meat mixture diets were widely used. Few of the feeding guides available today are based on actual bioenergetics data at different water temperatures and are adapted to high energy diets. New feeding standards have been developed based on principles of nutritional energetics in which the digestible energy content of diet, digestible protein and energy ratio and the amount of digestible energy required per unit of live weight gain are taken into account. The gain expressed as retained energy in carcass and maintenance energy at different water temperatures is the main criteria for energy and feed allocations. Series of bioenergetic models were developed based on these principles and a stand-alone multimedia program was written to facilitate computation of the models. This program predicts Growth and energy, nitrogen and phosphorus retention, requirements and excretions to determine feeding standards, waste outputs and effluent water quality based on a biological method. The models require initial and final body weights, water temperature, Growth Coefficient, carcass energy content and waste Coefficients to estimate input and output. Accurate determinations of the thermal-unit Growth Coefficient, apparent digestibility Coefficients and retention efficiencies are essential and these Coefficients are determined by biological experiments in the laboratory and field. Oxygen requirement is included to aid environmental control in fish culture system. The Fish-PrFEQ program also contains modules for production records, performance calculations and data base management for input and output data which may be exported for further data and graphic manipulations.
Andre Dumas - One of the best experts on this subject based on the ideXlab platform.
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evidence of three Growth stanzas in rainbow trout oncorhynchus mykiss across life stages and adaptation of the thermal unit Growth Coefficient
Aquaculture, 2007Co-Authors: Andre Dumas, Dominique P BureauAbstract:Current mathematical Growth models describe the Growth of finfish with few considerations of the changes in Growth pattern occurring across life stages. This study analysed the Growth pattern of rainbow trout and tried to improve the goodness of fit of an empirical Growth function. Growth data were obtained from 21 separate lots of rainbow trout (Ontario ARSTstrain) fed to satiation and reared at constant water temperature (8.5 °C) at the Alma Aquaculture Research Station, University of Guelph between 1997 and 2005. Growthrates(207observations)werecalculatedusingthethermal-unitGrowthCoefficient(TGC).CalculatedGrowthrateswereregressed againstlive body weight (BW). Piecewiselinear analysis was used to determine changes in the Growth pattern. This analysis revealed the existence of three Growth stanzas: from first-feeding (0.2 g) to 20 g (Stanza 1); from 20 to 500 g (Stanza 2); and N500 g (Stanza 3). The least squares method was used to optimize the weight exponent within each Growth stanza and to improve the goodness of fit of the TGC model.Resultsindicatedthatweightexponentsotherthan1 −b=1/3currentlyusedintheTGCmodelshouldbeusedforStanzas1and3. OnlytheweightexponentforStanza2wasnotsignificantlydifferentfromtheconventionalTGCmodelwhere1 −b=1/3(P ≥0.05).The weightexponentvaluesthatgavethebestfitwithinStanzas1and3were0.209and0.967,respectively.ThepredictedvaluesforBWwere overestimated for small fish (b20 g) and underestimated for large fish (N500 g) when using the exponent 1/3. The similarity between predictedandobservedBWforfishweighingbetween20–500gmeantthatthecuberootofBWissuitableforpredictingBWinStanza2. These results provide a more realistic Growth function that better fits the Growth pattern observed across the life stages of rainbow trout. © 2007 Elsevier B.V. All rights reserved.
