The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Taco Nicolai - One of the best experts on this subject based on the ideXlab platform.
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effect of kappa carrageenan on acid induced gelation of whey protein aggregates part i potentiometric titration rheology and turbidity
Food Hydrocolloids, 2020Co-Authors: Peng Zhou, Taco NicolaiAbstract:Abstract Gelation of suspensions of whey protein aggregates (WPA) was induced by lowering the pH in-situ using GDL. The effect of adding κ-carrageenan (KC) on the relationship between the Net Charge Density of the proteins (α) and the pH was determined by potentiometric titration. It showed that complexes were formed for α > −2. The effect of adding KC on the storage shear modulus and the turbidity was studied by oscillatory shear rheology and UV–Vis spectrometry. The KC concentration dependence was investigated up to 6 g/L at a fixed protein concentration of 20 g/L. Gels were formed for α > −3 in the absence of KC and α > −3.7 with 2 g/L KC, which was accompanied by an increase of the turbidity starting at the same α. The elastic modulus and the turbidity of the gels at steady state increased with increasing α. For a given α, a strong decrease of the elastic modulus and a strong increase of the turbidity were observed with increasing KC concentration. The effect of the gelation temperature was studied between 20 °C and 80 °C. The gelation rate increased strongly with increasing temperature and was controlled by the degradation rate of GDL, but it was not influenced by the KC concentration. Increasing the gelation temperature led to an increase of the elastic modulus and the turbidity at steady state.
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the effect of adding nacl on thermal aggregation and gelation of soy protein isolate
Food Hydrocolloids, 2017Co-Authors: Mouming Zhao, Nannan Chen, Christophe Chassenieux, Taco NicolaiAbstract:Abstract Thermal aggregation and gelation of soy protein isolate (SPI) was studied at fixed Charge Density over a wide range of protein concentrations (1–95 g/L), NaCl concentrations (0–0.5 M) and temperatures (30–85 °C). Gelation was studied with oscillatory shear measurements and aggregation with light scattering. At all conditions, self-similar aggregates were formed by random association of elementary units consisting of dense SPI particles with radii between 30 nm and 50 nm that were formed in a first step of the thermal aggregation process. Two distinct irreversible aggregation processes were identified: one dominating between 30 and 45 °C and one dominating above 65 °C. Addition of salt led to faster aggregation and gelation, but did not influence the gel stiffness at steady state. The size and Density of the elementary units of the aggregates increased with increasing NaCl concentration and confocal laser scanning microscopy images showed increasingly heterogeneous gels structures. The effect of varying the ionic strength on thermal aggregation is compared with that of varying the Net Charge Density of the proteins.
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Data on the characterization of native soy globulin by SDS-Page, light scattering and titration
Data in brief, 2016Co-Authors: Nannan Chen, Mouming Zhao, Christophe Chassenieux, Taco NicolaiAbstract:The data presented in this article are related to the research article entitled Structure of Self-assembled Native Soy Globulin in Aqueous Solution as a Function of the Concentration and the pH by N. Chen, M. Zhao C. Chassenieux, T. Nicolai (2016) [1]. Please refer to this article for interpretation of the data. The protein composition of soy protein isolate (SPI) was characterized by SDS-Page. The molar mass of native soy globulin aggregates formed at different protein concentrations was determined by light scattering as a function of the waiting time. The dependence of the pH on the Net Charge Density of native soy globulins was determined for solutions containing 5 g/L or 2 g/L SPI.
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structure of self assembled native soy globulin in aqueous solution as a function of the concentration and the ph
Food Hydrocolloids, 2016Co-Authors: Mouming Zhao, Nannan Chen, Christophe Chassenieux, Taco NicolaiAbstract:Aqueous solutions of native soy globulin were characterized using static and dynamic light scattering over a wide range of protein concentrations (1–100 g/L). The effect of the pH on salt free solutions was studied between the pH 5.8 and pH 7.0, while the effect of addition of monovalent salt was investigated at neutral pH. For pH > 6.4 soy globulin solutions free of aggregates can be obtained at low protein concentrations and very low ionic strength with weight average molar mass Mw = 3.0 ± 0.5 × 105 g/mol and hydrodynamic radius Rh = 9 ± 1 nm. At higher protein concentrations, soy globulin self-assembled into self-similar aggregates with a fractal dimension df = 1.8, with a size that increased with increasing concentration. The aggregates slowly dissociated over a period of weeks when the solutions were diluted. Self-assembly was also observed when the pH was decreased. The combined effects of pH and protein concentration on the self-assembly could be best understood by considering the Charge Density of the soy globulins. A sharp increase of Mw and Rh was observed when the Net Charge Density was reduced below a critical value.
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Formation and functionality of self-assembled whey protein microgels.
Colloids and surfaces. B Biointerfaces, 2015Co-Authors: Taco NicolaiAbstract:Abstract Whey proteins spontaneously form spherical particles when heated in aqueous solutions at conditions where their Net Charge Density is below a critical value. The particles are microgels consisting of a hydrated crosslinked Network of proteins with a diameter between 100 nm and 1 μm. Stable suspensions of these microgels can be formed in a narrow range of conditions when the protein Charge Density is low enough to induce their formation, but high enough to inhibit further association into larger clusters or macroscopic gels. The formation of microgels and their application to stabilize emulsions and foams; form core–shell particles; form gels; or modify the texture of polysaccharide solutions and gels are reviewed.
Nannan Chen - One of the best experts on this subject based on the ideXlab platform.
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the effect of adding nacl on thermal aggregation and gelation of soy protein isolate
Food Hydrocolloids, 2017Co-Authors: Mouming Zhao, Nannan Chen, Christophe Chassenieux, Taco NicolaiAbstract:Abstract Thermal aggregation and gelation of soy protein isolate (SPI) was studied at fixed Charge Density over a wide range of protein concentrations (1–95 g/L), NaCl concentrations (0–0.5 M) and temperatures (30–85 °C). Gelation was studied with oscillatory shear measurements and aggregation with light scattering. At all conditions, self-similar aggregates were formed by random association of elementary units consisting of dense SPI particles with radii between 30 nm and 50 nm that were formed in a first step of the thermal aggregation process. Two distinct irreversible aggregation processes were identified: one dominating between 30 and 45 °C and one dominating above 65 °C. Addition of salt led to faster aggregation and gelation, but did not influence the gel stiffness at steady state. The size and Density of the elementary units of the aggregates increased with increasing NaCl concentration and confocal laser scanning microscopy images showed increasingly heterogeneous gels structures. The effect of varying the ionic strength on thermal aggregation is compared with that of varying the Net Charge Density of the proteins.
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Data on the characterization of native soy globulin by SDS-Page, light scattering and titration
Data in brief, 2016Co-Authors: Nannan Chen, Mouming Zhao, Christophe Chassenieux, Taco NicolaiAbstract:The data presented in this article are related to the research article entitled Structure of Self-assembled Native Soy Globulin in Aqueous Solution as a Function of the Concentration and the pH by N. Chen, M. Zhao C. Chassenieux, T. Nicolai (2016) [1]. Please refer to this article for interpretation of the data. The protein composition of soy protein isolate (SPI) was characterized by SDS-Page. The molar mass of native soy globulin aggregates formed at different protein concentrations was determined by light scattering as a function of the waiting time. The dependence of the pH on the Net Charge Density of native soy globulins was determined for solutions containing 5 g/L or 2 g/L SPI.
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structure of self assembled native soy globulin in aqueous solution as a function of the concentration and the ph
Food Hydrocolloids, 2016Co-Authors: Mouming Zhao, Nannan Chen, Christophe Chassenieux, Taco NicolaiAbstract:Aqueous solutions of native soy globulin were characterized using static and dynamic light scattering over a wide range of protein concentrations (1–100 g/L). The effect of the pH on salt free solutions was studied between the pH 5.8 and pH 7.0, while the effect of addition of monovalent salt was investigated at neutral pH. For pH > 6.4 soy globulin solutions free of aggregates can be obtained at low protein concentrations and very low ionic strength with weight average molar mass Mw = 3.0 ± 0.5 × 105 g/mol and hydrodynamic radius Rh = 9 ± 1 nm. At higher protein concentrations, soy globulin self-assembled into self-similar aggregates with a fractal dimension df = 1.8, with a size that increased with increasing concentration. The aggregates slowly dissociated over a period of weeks when the solutions were diluted. Self-assembly was also observed when the pH was decreased. The combined effects of pH and protein concentration on the self-assembly could be best understood by considering the Charge Density of the soy globulins. A sharp increase of Mw and Rh was observed when the Net Charge Density was reduced below a critical value.
Toeno Van Der Sar - One of the best experts on this subject based on the ideXlab platform.
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Exciton-to-trion conversion as a control mechanism for valley polarization in room-temperature monolayer WS$_\text{2}$
Scientific reports, 2020Co-Authors: Joris J. Carmiggelt, Michael Borst, Toeno Van Der SarAbstract:Transition metal dichalcogenide (TMD) monolayers are two-dimensional semiconductors with two valleys in their band structure that can be selectively addressed using circularly polarized light. Their photoluminescence spectrum is characterized by neutral and Charged excitons (trions) that form a chemical equilibrium governed by the Net Charge Density. Here, we use chemical doping to drive the conversion of excitons into trions in $\text{WS}_{2}$ monolayers at room temperature, and study the resulting valley polarization via photoluminescence measurements under valley-selective optical excitation. We show that the doping causes the emission to become dominated by trions with a strong valley polarization associated with rapid non-radiative recombination. Simultaneously, the doping results in strongly quenched but highly valley-polarized exciton emission due to the enhanced conversion into trions. A rate equation model explains the observed valley polarization in terms of the doping-controlled exciton-trion equilibrium. Our results shed light on the important role of exciton-trion conversion on valley polarization in monolayer TMDs.
Joris J. Carmiggelt - One of the best experts on this subject based on the ideXlab platform.
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Exciton-to-trion conversion as a control mechanism for valley polarization in room-temperature monolayer WS$_\text{2}$
Scientific reports, 2020Co-Authors: Joris J. Carmiggelt, Michael Borst, Toeno Van Der SarAbstract:Transition metal dichalcogenide (TMD) monolayers are two-dimensional semiconductors with two valleys in their band structure that can be selectively addressed using circularly polarized light. Their photoluminescence spectrum is characterized by neutral and Charged excitons (trions) that form a chemical equilibrium governed by the Net Charge Density. Here, we use chemical doping to drive the conversion of excitons into trions in $\text{WS}_{2}$ monolayers at room temperature, and study the resulting valley polarization via photoluminescence measurements under valley-selective optical excitation. We show that the doping causes the emission to become dominated by trions with a strong valley polarization associated with rapid non-radiative recombination. Simultaneously, the doping results in strongly quenched but highly valley-polarized exciton emission due to the enhanced conversion into trions. A rate equation model explains the observed valley polarization in terms of the doping-controlled exciton-trion equilibrium. Our results shed light on the important role of exciton-trion conversion on valley polarization in monolayer TMDs.
Christophe Chassenieux - One of the best experts on this subject based on the ideXlab platform.
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the effect of adding nacl on thermal aggregation and gelation of soy protein isolate
Food Hydrocolloids, 2017Co-Authors: Mouming Zhao, Nannan Chen, Christophe Chassenieux, Taco NicolaiAbstract:Abstract Thermal aggregation and gelation of soy protein isolate (SPI) was studied at fixed Charge Density over a wide range of protein concentrations (1–95 g/L), NaCl concentrations (0–0.5 M) and temperatures (30–85 °C). Gelation was studied with oscillatory shear measurements and aggregation with light scattering. At all conditions, self-similar aggregates were formed by random association of elementary units consisting of dense SPI particles with radii between 30 nm and 50 nm that were formed in a first step of the thermal aggregation process. Two distinct irreversible aggregation processes were identified: one dominating between 30 and 45 °C and one dominating above 65 °C. Addition of salt led to faster aggregation and gelation, but did not influence the gel stiffness at steady state. The size and Density of the elementary units of the aggregates increased with increasing NaCl concentration and confocal laser scanning microscopy images showed increasingly heterogeneous gels structures. The effect of varying the ionic strength on thermal aggregation is compared with that of varying the Net Charge Density of the proteins.
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Data on the characterization of native soy globulin by SDS-Page, light scattering and titration
Data in brief, 2016Co-Authors: Nannan Chen, Mouming Zhao, Christophe Chassenieux, Taco NicolaiAbstract:The data presented in this article are related to the research article entitled Structure of Self-assembled Native Soy Globulin in Aqueous Solution as a Function of the Concentration and the pH by N. Chen, M. Zhao C. Chassenieux, T. Nicolai (2016) [1]. Please refer to this article for interpretation of the data. The protein composition of soy protein isolate (SPI) was characterized by SDS-Page. The molar mass of native soy globulin aggregates formed at different protein concentrations was determined by light scattering as a function of the waiting time. The dependence of the pH on the Net Charge Density of native soy globulins was determined for solutions containing 5 g/L or 2 g/L SPI.
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structure of self assembled native soy globulin in aqueous solution as a function of the concentration and the ph
Food Hydrocolloids, 2016Co-Authors: Mouming Zhao, Nannan Chen, Christophe Chassenieux, Taco NicolaiAbstract:Aqueous solutions of native soy globulin were characterized using static and dynamic light scattering over a wide range of protein concentrations (1–100 g/L). The effect of the pH on salt free solutions was studied between the pH 5.8 and pH 7.0, while the effect of addition of monovalent salt was investigated at neutral pH. For pH > 6.4 soy globulin solutions free of aggregates can be obtained at low protein concentrations and very low ionic strength with weight average molar mass Mw = 3.0 ± 0.5 × 105 g/mol and hydrodynamic radius Rh = 9 ± 1 nm. At higher protein concentrations, soy globulin self-assembled into self-similar aggregates with a fractal dimension df = 1.8, with a size that increased with increasing concentration. The aggregates slowly dissociated over a period of weeks when the solutions were diluted. Self-assembly was also observed when the pH was decreased. The combined effects of pH and protein concentration on the self-assembly could be best understood by considering the Charge Density of the soy globulins. A sharp increase of Mw and Rh was observed when the Net Charge Density was reduced below a critical value.