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Researchers at Bar Ilan University in Ramat-Gan, Israel have developed superparamagnetic amine-functionalized maghemite nanoparticles that can be used to promote thixotropy in hydrogels and enable magnetic field-driven diffusion-controlled drug release. The nanoparticles were synthesized and incorporated into a tough elastomeric hydrogel, which was tested for its mechanical properties and drug release behavior. The hybrid hydrogel showed delayed network rupturing, dual-responsive drug delivery, and noncytotoxic behavior, making it a promising candidate for remotely controlled drug delivery. The research has been peer-reviewed and published in ACS Applied Nano Materials. [Extracted from the article]

In order to describe the mechanical behaviors of viscoelastic materials that couple memory effects and time-varying viscosity properties toggled between thixotropy and rheopexy, this paper explores and establishes the constitutive equation of a unified Maxwell model with a variable kernel in terms of the ψ -Caputo fractional derivative. By virtue of a Volterra integral equation of the second kind and the ψ -Laplace transform technique, the closed-form expressions of creep and relaxation responses for the proposed model are derived and compared in detail. Furthermore, to enhance practicality, the exponential and power-law time-varying viscosity candidates are embedded into the proposed model, along with exhibiting the corresponding creep and relaxation behaviors in light of illustration and reasoning, respectively. The results may provide a fresh perspective for detecting the relationship between the viscoelastic system with nonlinear time-varying viscosity and generalized fractional calculus. [ABSTRACT FROM AUTHOR]

In the present work, we implement thixotropic–viscoelastic models in the HiGFlow system, which is a recently developed Computational Fluid Dynamics software that is able to simulate Newtonian, Generalized-Newtonian and viscoelastic flows using finite differences in tree-based grids. The system uses a moving least squares meshless interpolation technique, allowing to use more complex mesh configurations, still keeping the overall order of accuracy. We provide here a brief introduction to each of the implemented models (the Bautista–Manero–Puig, the Modified-Bautista, the NM_ τ p and NM_ T models), where we describe their parameters, their strengths and their limitations. Unlike previous numerical works focused on this kind of fluids, non-zero Reynolds number numerical simulations of these models are carried out here in HiGFlow using different geometries like 2D channels, planar contraction 4:1 and 4:1:4 and our results are compared with those predicted by RheoTool , an open-source toolbox based on OpenFOAM. Although the transient numerical solutions differ, we observe that there is an excellent agreement in the steady-state profiles obtained in both software. A discussion of our results and their physical interpretation, a comparison with previously published results in the literature and a deep analysis of the corner vortex behaviour in the contraction geometries are also presented. Moreover, we show that our methodology offers flexibility and stability in the numerical simulations of thixotropic–viscoelastic flows for structured fluids, which allows the users to accurately simulate rheological behaviour of interest. • Thixotropic–viscoelastic models are implemented in a new CFD software called HiGFlow. • Simulations are carried out in 2D-channel and planar-contraction geometries at Re ≠ 0. • We compare directly our simulations with results predicted by the RheoTool system. • A comparison with previously published results in the literature is shown. • Transient solutions of stresses and analysis of vortex behaviour are presented. [ABSTRACT FROM AUTHOR]

Researchers at Shanghai Jiao Tong University in China have conducted a study on dysphagia, a condition characterized by difficulty swallowing. The study focused on the use of thixotropic yield fluids (YSFs) in dysphagia management, which are thickened or gelled with polysaccharide gums. The researchers investigated the time-dependent thixotropy of these solutions and analyzed the relationship between their mechanical properties and structural changes. The study found that different polysaccharide solutions exhibited varying levels of thixotropy, which were attributed to their different intermolecular associations and networks. This research provides valuable insights into the manufacturing application of YSFs for dysphagia management. [Extracted from the article]

According to Einstein's viscosity formula, the effective viscosity of a suspension is related to the volume fraction ϕ of suspended particles. Higher-order terms, which include contributions from hydrodynamic interactions, become more important when the concentration of the suspension reaches around 25%. The coefficient β of the term quadratic in ϕ , however, has not been incontrovertibly validated. In order to investigate the effects on the macroscopic rheology of a suspension due to the rotational motions of the microscopic suspended particles—which are usually neglected in analytical and numerical studies—we have performed simulations of a pressure-driven flow using a two-way coupling method (defined in text). We used the regularized lattice Boltzmann equation for the fluid part of the calculation, and we employed Newton's second law of motion and the equation of angular motion for the translational and rotational motions of the rigid particles. As a result, we found that the particles rotate to achieve kinetic balance with the surrounding hydrodynamic forces, which results in a decrease in fluid resistance. It is therefore important to take into account the particles’ rotational motions and the accompanying changes in the flow field in order to evaluate the effective viscosity of a suspension. The spatial variation of the relative viscosity determined from the wall shear stress becomes more significant with increasing area fraction. We found that the value of the coefficient β may increase due to hydrodynamic resistance against the rotational motions of the particles. [ABSTRACT FROM AUTHOR]

The article discusses the thixotropic property of ketchup.

The previous article defined yield stress and explained how to calculate the amount needed for a given application. Here, methods for measuring yield stress are compared by determining the values of two materials: a nonthixotropic acrylates copolymer solution, and a thixotropic body wash. The results provide recommendations for methods in terms of relevance, exactness and robustness. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, laminar, two-dimensional flow of an incompressible thixotropic fluid obeying Harris rheological model is investigated above a fixed semi-infinite plate- the so-called Blasius flow. Assuming that the flow is occurring at high Reynolds number, use will be made of the boundary layer theory to simplify the equations of motion. The equations so obtained are then reduced to a single fourth-order ODE using a suitable similarity variable. It is shown that Harris fluids do not render themselves to a self-similar solution in Blasius flow. A local similarity solution is found which enabled investigating the effects of the model parameters on the velocity profile and wall shear stress at a given location above the plate. Numerical results show that for the Harris model to represent thixotropic fluids, the sign and magnitude of the material parameters appearing in this fluid model cannot be arbitrary. [Copyright &y& Elsevier]

This paper describes the correlation between the structure of liquid crystalline phases in emulsions and their rheological characteristics. An oleosome/lipophilic liquid crystalline-forming system and hydrosome/hydrophilic liquid crystalline-forming system were investigated. At the same high shear rate viscosity, the oleosome-system showed less thixotropy and rapid recovery when compared with the hydrosome-system. [ABSTRACT FROM AUTHOR]

The combined knowledge of rheology and chemistry of binders together with the art of proper formulation leads to the production of aesthetically pleasing dentifrice formulations. [ABSTRACT FROM AUTHOR]

The article discusses history of the ballpoint pen invention which invented by a tanner John J. Loud in 1888. Topics include the first ballpoint pen write on leather but in 1935 an improved version was invented in Hungary by Ladislas Jose Biro; a chemist Fran Speech working on improvements in ballpoint ink in 1949; and also mentions about the Fisher Space Pen invented by Paul C. Fisher, an American inventor and politician, which works with thixotropic ink and a pressurized ink cartridge.

The article provides information on how a soft-tissue technique works during a massage. According to the author, the connective tissue or fascia is the immediate environment of a cell wherein it alters its input and freely moves and reacts in a way that can make people have healthier condition. She adds that during a massage thixotropy, connective tissue's capability to change state occurs to provide amelioration to the body and thus changing its state to render a suitable body condition.

In a brief article, the author discusses the property of thixotropy in clay-based casting slips. The author explains that thixotropy, or the property of a fluid that gels or hardens at rest but becomes more liquid with vigorous agitation, can both help or hurt the ceramic process. Casting slips that are thixotropic are desirable because they add firmness to the cast. However, the disadvantage of thixotropic slips or glazes is that they need to be shaken in order to be poured.

Presents information on how to make thixotropic solutions.

The article focuses on the launch of the three series of rotation sensing transducer (RST) touch screen rheometers including the RST Cone Plate Rheometer, the RST Coaxial Cylinder Rheometer and the RST Soft Solids Tester Rheometer for thixotropy calculation and flow measurement from Brookfield.

The article discusses research examining a new method to quantitatively describe thixotropy in waxy crude oil. Regarded as an important rheological attribute of waxy crude oil, several groups of thixotropic experimental data were gathered from two waxy crude oil pipelines. While some thixotropic models deal with structure irreversibility, the weakening of waxy structure under shear action is reflected through thixotropic behavior. Maximum and equilibrium shear stress data gathered are cited.

This article offers information on a new class of elastomer that offer higher performance for longer durations at more temperature extremes. According to Wayne Rodrigue of Exousia Advanced Materials, the company's rubber process analyzer (RPA) thermoplastic olefin can also eliminate exposure to hydrogen peroxide as a manufacturing step. There have been efforts by Exousia to develop commercial applications for the technology. Rodrigue claims the material gets tougher as the temperature gets colder and exhibits thixotropic properties when melted.

The article discusses the application of thixomolding in producing lightweight wheels for motorcycles. In the summer of 2007, DatuMag of Ontario, Canada, was employed by an aftermarket supplier of high performance motorcycle parts to develop the wheels. DatuMag was founded by Cana-Datum Molds Ltd. It specializes in thixomolding, an emerging technology that presents a more cost-effective way to produce magnesium alloy castings. The challenges of developing the wheels are mentioned. Advantages of thixomolding are explained.

The article features a method for determining the maximum shutdown time of a waxy crude oil pipeline, that can yield savings in heating costs compared to subjective methods employed before a pipeline enters service. It is stated that pipeline operators often heat waxy crude lines to ensure safe and economic transport. It is also stated that shutdowns lower the oil temperature thereby increasing its viscosity and strengthening thixotropic tendencies that require a large start-up pressure.

The article features Ultradent Products Inc.'s Clone Bite, which is a thixotropic material designed to provide resistance for exact placement in the mouth without making it difficult for patients to occlude.

Reveals that a property known as thixotropy may explain a centuries old miracle. Blood, once congealed, tends to stay that way. But when religious leaders handle a vial believed to contain the blood of Saint Januarius, the dark brown substance begins to flow. Periodic demonstrations of this effect have drawn crowds to Naples, Italy, since 1389, notes Luigi Garlaschelli, an organic chemist at the University of Pavia in Italy. In the October 10, 1991 issue of "Nature," Garlaschelli and two other Italian researchers propose that medieval alchemists could have created a thixotropic substance that looked like blood by mixing water and salt with a mineral called molysite. To explore this possibility, Garlaschelli searched through the scientific literature and discovered that about 70 years ago, researchers demonstrated thixotropy in an iron hydroxide alloy. He reproduced their work by mixing a ferric chloride compound with calcium carbonate in water, then separating out the iron hydroxide that formed.