Particle Stability in Dilute Fermented Dairy Drinks: Formation of Fluid Gel and Impact on Rheological Properties

2010 ◽  
Vol 16 (6) ◽  
pp. 543-551 ◽  
Author(s):  
H. Kiani ◽  
M.E. Mousavi ◽  
Z.E. Mousavi
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Colloidal Particles ◽  
Solid Particles ◽  
Particle Stability ◽  
Wide Availability ◽  
Application Potential ◽  
Transient Interactions ◽  
The Stability ◽  
Fermented Dairy

Fluid gels are known to be very shear-thinning materials with yield stress. In this study, the rheological properties of gellan and gellan—pectin fluid gels in fermented dairy drinks were evaluated using viscometric measurements. Both gellan- and gellan—pectin-containing solutions showed the rheological properties of fluid gels resulting in stabilization of particles; but no evidence of a fluid gel was observed for those with pectin alone and those with no hydrocolloid content. Unlike pectin, gellan gum was capable of creating significant values of yield stress and accordingly stabilized colloidal particles and extrinsic added solid particles in the fermented dairy drink. However, pectin improved the stability in combination with gellan. The origin of fluid gel formation was assumed to be both permanent interactions occurring between gellan and proteins, forming hairy particle gels and transient interactions between the particle gels. The significance of yield stress values for particle stability was demonstrated and two methods, including a noteworthy infinite apparent viscosity method and a conventional Bingham approach, were employed to calculate the values of yield stress. Both the methods showed a good application potential due to their simplicity, reasonable results and also wide availability of the instrument applied.

The Coarse Particle Influence on the Strength of Wax Deposition

2020 ◽  
Author(s):  
Xun Zhang ◽  
Qiyu Huang ◽  
Yu Zhang ◽  
Yaping Li ◽  
Xin Liu
Keyword(s):  
Yield Stress ◽  
Colloidal Particles ◽  
Critical Mass ◽  
Solid Particles ◽  
Coarse Particle ◽  
Silica Sand ◽  
Coarse Particles ◽  
Wax Deposition ◽  
Wax Deposits ◽  
The Impact

Abstract Wax deposition has always been an essential issue for flow assurance, especially in subsea pipelines. The coarse particles, which are usually measured in millimeters, will be carried out by oil flow during the deep-water oil fields production. However, due to insufficient understanding of the structure of wax deposits and the complexity of sandy crude oil deposition, the interaction between coarse particles and wax deposits in the pipeline have rarely been investigated. In this paper, the effect of coarse particles on the yield stress of wax deposits has been studied. The sample was mixed at reversible structure temperature so that the impact of shear history could be eliminated, and the rapid particle settlement at high temperature could be avoided. Experimental results have found that there is a critical fraction in coarse particle influences, below which a small number of coarse particles added will lead to a slight increase in bulk yield stress. On the contrary, a dramatic decrease in yield stress when exceeding the critical mass fraction and increasingly marked enhancement of yield stress as the fraction increases. This phenomenon has been explicated microscopically by the structural interaction between coarse particles and wax deposits. The interlock between wax crystals is the major contribution of the structure as the less particle fraction contains. Even though the silica sand is a typical non-colloidal particle, the asphaltene and resin could be absorbed on the surface of particles and forming a cluster of colloidal particles. As the fraction of particles slightly increased, the slip between colloidal particles and wax crystal interlock accelerates structural failure. Nevertheless, more particles involved the overall yield stress may depend on the friction and the adhesive force between solid particles. The subtle changes induced by coarse particles would have a harder deposit, which can hinder pig passing and affect pipeline pigging operations.

scholarly journals Impact of organophilic clay on rheological properties of gasoil-based drilling muds

2020 ◽  
Vol 10 (8) ◽  
pp. 3533-3540
Author(s):  
Cheikh Bergane ◽  
Larbi Hammadi
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Yield Stress ◽  
Drilling Mud ◽  
Flow Curves ◽  
Casson Model ◽  
Organophilic Clay ◽  
The Stability ◽  
Drilling Muds ◽  
The Impact

Abstract In this study, the impact of VG69 organophilic clay on the rheological properties of gasoil-based drilling muds (invert emulsions) was investigated. The flow curves of gasoil-based drilling muds as a function of the dose of VG69 organophilic clay were analyzed by the Casson model. The addition of VG69 organophilic clay with a quantity range between 0 and 5 g in gasoil-based drilling muds induces an increase in the yield stress and the viscosity at an infinite shear rate of drilling muds. It is also proven that the addition of VG69 organophilic clay leads to an increase in the viscoelastic and thixotropic properties of the drilling muds. The study of the stability of gasoil-based drilling muds by centrifugation showed that for a quantity of VG69 organophilic clay lower than 3 g, the stability of the drilling muds increases and for a quantity of VG69 organophilic clay higher than 3 g, their stability decreases. The results obtained showed that the addition of 3 g of VG69 organophilic clay to the gasoil-based drilling mud increased the yield stress by 230%, the viscosity at an infinite shear rate by 3.4% and it improved the mud stability by 70%.

The Rheological Properties and Yield Stress Model of High-Density Slurry Added with Coarse Sands

2014 ◽  
Vol 580-583 ◽  
pp. 231-237 ◽  
Author(s):  
Xiu Xiang Zhang ◽  
Deng Pan Qiao
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Mass Concentration ◽  
Cement Content ◽  
Coarse Sand ◽  
High Density ◽  
Rheological Parameters ◽  
Suitable Model ◽  
Bingham Plastic ◽  
The Stability

In order to determine the concentration range of high-density slurry with coarse sands for suiting pipeline transportation in Jinchuan mine, at the same time find a suitable model to predict yield stress. In this paper, based on the coarse sand of Jinchuan mine as material to prepare high-density slurry, studied on the rheological properties. Through two-factor variance analysis, qualitative and ration analysis of the effect was conducted on the cement content and mass concentration to rheological parameters. The results show that the rheological model of the coarse sand is similar to that of Bingham plastic fluid, the mass concentration has a significant effect on viscosity and yield stress, and the viscosity is significantly affected by the cement content. The mass concentration of 82%-84% is suitable gravity transportation in pipeline. Meanwhile the relation model is established between yield stress and water-cement ratio, aggregate volume concentration, the model has high precision. These provide technical basis for designing filling system and ensuring the stability of slurry transportation, and a new idea for the research of rheological properties.

Catalytic Enantioselective Benzylation Directly from Aryl Acetic Acids

2018 ◽  
Author(s):  
Patrick Moon ◽  
Zhongyu Wie ◽  
Rylan Lundgren
Keyword(s):  
Functional Group ◽  
Terminal Event ◽  
Radical Intermediates ◽  
Carbon Carbon Bond ◽  
Or Groups ◽  
Reaction Proceeds ◽  
Wide Availability ◽  
Metal Catalyzed ◽  
The Stability ◽  
Acetic Acids

The stability and wide availability of carboxylic acids make them valuable reagents in chemical synthesis. Most transition metal catalyzed processes using carboxylic acid substrates are initiated by a decarboxylation event that generates reactive carbanion or radical intermediates. Developing enantioselective methodologies relying on these principles can be challenging, as highly reactive species tend to react indiscriminately without selectivity. Furthermore, anionic or radical intermediates generated from decarboxylation can be incompatible with protic and electrophilic functionality, or groups that undergo trapping with radicals. We demonstrate that metal-catalyzed enantioselective benzylation reactions of allylic electrophiles can occur directly from aryl acetic acids. The reaction proceeds via a pathway in which decarboxylation is the terminal event, occurring after stereoselective carbon–carbon bond formation. The mechanistic features of the process enable enantioselective benzylation without the generation of a highly basic nucleophile. Thus, the process has broad functional group compatibility that would not be possible employing established protocols.<br>

scholarly journals State-Space Model of Quasi-Z-Source Inverter-PV Systems for Transient Dynamics Studies and Network Stability Assessment

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4150
Author(s):  
Lluís Monjo ◽  
Luis Sainz ◽  
Juan José Mesas ◽  
Joaquín Pedra
Keyword(s):  
Power Systems ◽  
State Space ◽  
State Space Model ◽  
Pv System ◽  
Pv Systems ◽  
Renewable Power ◽  
Ac Networks ◽  
Transient Interactions ◽  
The Stability ◽  
Averaged Model

Photovoltaic (PV) power systems are increasingly being used as renewable power generation sources. Quasi-Z-source inverters (qZSI) are a recent, high-potential technology that can be used to integrate PV power systems into AC networks. Simultaneously, concerns regarding the stability of PV power systems are increasing. Converters reduce the damping of grid-connected converter systems, leading to instability. Several studies have analyzed the stability and dynamics of qZSI, although the characterization of qZSI-PV system dynamics in order to study transient interactions and stability has not yet been properly completed. This paper contributes a small-signal, state-space-averaged model of qZSI-PV systems in order to study these issues. The model is also applied to investigate the stability of PV power systems by analyzing the influence of system parameters. Moreover, solutions to mitigate the instabilities are proposed and the stability is verified using PSCAD time domain simulations.

scholarly journals Effect of Photoinitiator on Precursory Stability and Curing Depth of Thiol-Ene Clickable Gelatin

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1877
Author(s):  
Kai-Hung Yang ◽  
Gabriella Lindberg ◽  
Bram Soliman ◽  
Khoon Lim ◽  
Tim Woodfield ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Visible Light ◽  
Rheological Properties ◽  
Swelling Ratio ◽  
Sodium Persulfate ◽  
Photo Polymerization ◽  
Gelation Kinetics ◽  
The Stability ◽  
Over Time

Recent advances highlight the potential of photopolymerizable allylated gelatin (GelAGE) as a versatile hydrogel with highly tailorable properties. It is, however, unknown how different photoinitiating system affects the stability, gelation kinetics and curing depth of GelAGE. In this study, sol fraction, mass swelling ratio, mechanical properties, rheological properties, and curing depth were evaluated as a function of time with three photo-initiating systems: Irgacure 2959 (Ig2959; 320–500 nm), lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP; 320–500 nm), and ruthenium/sodium persulfate (Ru/SPS; 400–500 nm). Results demonstrated that GelAGE precursory solutions mixed with either Ig2959 or LAP remained stable over time while the Ru/SPS system enabled the onset of controllable redox polymerization without irradiation during pre-incubation. Photo-polymerization using the Ru/SPS system was significantly faster (<5 s) compared to both Ig2959 (70 s) and LAP (50 s). Plus, The Ru/SPS system was capable of polymerizing a thick construct (8.88 ± 0.94 mm), while Ig2959 (1.62 ± 0.49 mm) initiated hydrogels displayed poor penetration depth with LAP (7.38 ± 2.13 mm) in between. These results thus support the use of the visible light based Ru/SPS photo-initiator for constructs requiring rapid gelation and a good curing depth while Ig2959 or LAP can be applied for photo-polymerization of GelAGE materials requiring long-term incubation prior to application if UV is not a concern.

scholarly journals Comparison of the Effects of Conching Parameters on the Contents of Three Dominant Flavan3-ols, Rheological Properties and Sensory Quality in Chocolate Milk Mass Based on Liquor from Unroasted Cocoa Beans

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2502
Author(s):  
Bogumiła Urbańska ◽  
Hanna Kowalska ◽  
Karolina Szulc ◽  
Małgorzata Ziarno ◽  
Irina Pochitskaya ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Sensory Quality ◽  
Raw Material ◽  
Antioxidant Compounds ◽  
Chocolate Milk ◽  
Cocoa Beans ◽  
Variable Parameters ◽  
The Relationship ◽  
Manufacturing Parameters

The content of polyphenols in chocolate depends on many factors related to the properties of raw material and manufacturing parameters. The trend toward developing chocolates made from unroasted cocoa beans encourages research in this area. In addition, modern customers attach great importance to how the food they consume benefits their bodies. One such benefit that consumers value is the preservation of natural antioxidant compounds in food products (e.g., polyphenols). Therefore, in our study we attempted to determine the relationship between variable parameters at the conching stage (i.e., temperature and time of) and the content of dominant polyphenols (i.e.,catechins, epicatechins, and procyanidin B2) in chocolate milk mass (CMM) obtained from unroasted cocoa beans. Increasing the conching temperature from 50 to 60 °C decreased the content of three basic flavan-3-ols. The highest number of these compounds was determined when the process was carried out at 50 °C. However, the time that caused the least degradation of these compounds differed. For catechin, it was 2 h; for epicatechin it was 1 h; and for procyanidin it was 3 h. The influence of both the temperature and conching time on the rheological properties of chocolate milk mass was demonstrated. At 50 °C, the viscosity and the yield stress of the conched mass showed its highest value.

scholarly journals Carbon Nanomaterials for Enhancing the Thermal, Physical and Rheological Properties of Asphalt Binders

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2585
Author(s):  
Zhelun Li ◽  
Xin Yu ◽  
Yangshi Liang ◽  
Shaopeng Wu
Keyword(s):  
High Temperature ◽  
Rheological Properties ◽  
Carbon Nanomaterials ◽  
Asphalt Binders ◽  
Snow Melting ◽  
Temperature Performance ◽  
Unique Nature ◽  
Application Potential ◽  
Urban Heat ◽  
Two Parameters

Effective thermal conduction modification in asphalt binders is beneficial to reducing pavement surface temperature and relieving the urban heat island (UHI) effect in the utilization of solar harvesting and snow melting pavements. This study investigated the performance of two nanometer-sized modifiers, graphene (Gr) and carbon nanotubes (CNTs), on enhancing the thermal, physical and rheological properties of asphalt binders. Measurements depending on a transient plant source method proved that both Gr and CNTs linearly increased the thermal conductivity and thermal diffusivity of asphalt binders, and while 5% Gr by volume of matrix asphalt contributed to 300% increments, 5% CNTs increased the two parameters of asphalt binders by nearly 72% at 20 °C. Meanwhile, a series of empirical and rheological properties experiments were conducted. The results demonstrated the temperature susceptibility reduction and high-temperature properties promotion of asphalt binders by adding Gr or CNTs. The variation trends in the anti-cracking properties of asphalt binders modified by Gr and CNTs with the modifier content differed at low temperatures, which may be due to the unique nature of Gr. In conclusion, Gr, whose optimal content is 3% by volume of matrix asphalt, provides superior application potential for solar harvesting and snow melting pavements in comparison to CNTs due to its comprehensive contributions to thermal properties, construction feasibility, high-temperature performance and low-temperature performance of asphalt binders.

scholarly journals Facile Organometallic Synthesis of Fe-Based Nanomaterials by Hot Injection Reaction

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1141
Author(s):  
Georgia Basina ◽  
Hafsa Khurshid ◽  
Nikolaos Tzitzios ◽  
George Hadjipanayis ◽  
Vasileios Tzitzios
Keyword(s):  
Room Temperature ◽  
Colloidal Particles ◽  
Iron Pentacarbonyl ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
Organometallic Synthesis ◽  
X Ray ◽  
Transmission Electron ◽  
Hot Injection ◽  
The Stability

Fe-based colloids with a core/shell structure consisting of metallic iron and iron oxide were synthesized by a facile hot injection reaction of iron pentacarbonyl in a multi-surfactant mixture. The size of the colloidal particles was affected by the reaction temperature and the results demonstrated that their stability against complete oxidation related to their size. The crystal structure and the morphology were identified by powder X-ray diffraction and transmission electron microscopy, while the magnetic properties were studied at room temperature with a vibrating sample magnetometer. The injection temperature plays a very crucial role and higher temperatures enhance the stability and the resistance against oxidation. For the case of injection at 315 °C, the nanoparticles had around a 10 nm mean diameter and revealed 132 emu/g. Remarkably, a stable dispersion was created due to the colloids’ surface functionalization in a nonpolar solvent.

Film Elasticity and Film Stabilization in Firefighting Foam Stabilized by Solid Particles

2017 ◽  
Vol 744 ◽  
pp. 346-349
Author(s):  
Xiu Juan Li ◽  
Rui Song Guo ◽  
Min Zhao
Keyword(s):  
Life Time ◽  
Liquid Films ◽  
Thin Liquid Films ◽  
Solid Particles ◽  
High Concentration ◽  
Hydration Effect ◽  
Fixed Area ◽  
The Stability ◽  
Hydration Layers ◽  
Hydration Forces

The structure of the thin liquid films determines the stability of foams and emulsions. In this work the bubbles stretched length with different hollow SiO2 particles concentration is measured when the foam has been stilled for different time. The results show that the bubbles stretched length is longer than that of bubbles when the foam is free of hollow SiO2 particles even when the foam has been stilled for 500mins. The bubbles stretched length increases with increasing the concentration of hollow SiO2 particles. A strong hydration effect leaves a large volume of hydration layers on the solid particles surfaces in aqueous solutions. The water in hydration layers can help the film keep a certain thickness. The existence of hydration forces leads that two particles cannot be too close each other. The high concentration surfactant limited in the fixed area helps the film keep good elasticity. Therefore the film has a long life time with compatible thickness and elasticity and the three-phrase foam is upper stable.

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