Abstract Dispersion of Basil seed gum has high viscosity and exhibits shear-thinning behavior. This study aimed to analyze the influence of microwave treatment (MT) at various time intervals (0, 1, ...2, and 3 min) on the viscosity and rheological behavior of Basil seed gum dispersion (0.5%, w/v). The finding of this study revealed that the apparent viscosity of Basil seed gum dispersion (non-treated dispersion) reduced from 0.330 Pa.s to 0.068 Pa.s as the shear rate (SR) increased from 12.2 s −1 to 171.2 s −1 . Additionally, the apparent viscosity of the Basil seed gum dispersion reduced from 0.173 Pa.s to 0.100 Pa.s as the MT time increased from 0 to 3 min (SR = 61 s −1 ). The rheological properties of gum dispersion were successfully modeled using Power law (PL), Bingham, Herschel–Bulkley (HB), and Casson models, and the PL model was the best one for describing the behavior of Basil seed gum dispersion. The PL model showed an excellent performance with the maximum r-value (mean r-value = 0.942) and the minimum sum of squared error (SSE) values (mean SSE value = 5.265) and root mean square error (RMSE) values (mean RMSE value = 0.624) for all gum dispersion. MT had a considerable effect on the changes in the consistency coefficient (k-value) and flow behavior index (n-value) of Basil seed gum dispersion ( p < 0.05). The k-value of Basil seed gum dispersion decreased significantly from 3.149 Pa.s n to 1.153 Pa.s n ( p < 0.05) with increasing MT time from 0 to 3 min. The n-value of Basil seed gum dispersion increased significantly from 0.25 to 0.42 ( p < 0.05) as the MT time increased. The Bingham plastic viscosity of Basil seed gum dispersion increased significantly from 0.029 Pa.s to 0.039 Pa.s ( p < 0.05) while the duration of MT increased. The Casson yield stress of Basil seed gum dispersion notably reduced from 5.010 Pa to 2.165 Pa ( p < 0.05) with increasing MT time from 0 to 3 min.
In present work, the abrasive-free jet polishing (AFJP) of bulk single-crystal KDP was first fulfilled, when using a newly-designed low-viscosity microemulsion as the AFJP fluid. The novel AFJP fluid ...shows a typical water-in-oil structure, in which the water cores uniformly distribute in the BmimPF6 IL, with a particle size of about 20-25 nm. What's more, the AFJP fluid is a controllable and selective non-abrasive jet fluid that the shape of the removal function is regular and smooth, presenting a similar Gaussian function, meanwhile, the dispersion coefficient of the removal rate is only 1.9%. Finally, the surface quality of the bulk single-crystal KDP is further improved by AFJP, meanwhile, the subsurface damage is first obviously mitigated.
In the present work, we demonstrate that zero‐shear viscosity is a sensitive rheological function to detect phase inversion in immiscible binary polymer blends characterized by a viscosity ratio ...larger than one. The phase inversion of poly(propylene) (PP)/low‐density poly(ethylene) (LDPE) and poly(styrene) (PS)/LDPE, at various compositions, was assessed via our novel approach. For both blends, three distinctive regions could be determined through zero‐shear viscosity measurements; the LDPE matrix, the co‐continuous phase, and the PS or PP matrix. For PP/LDPE blends, the co‐continuous structure was between 50 and 75 wt.% PP, and for PS/LDPE blends the co‐continuous structure was between 45 and 75 wt.% PS, in agreement with scanning electron microscopy analysis, empirical model predictions, and literature data.
Highlights
Phase inversion revealed via viscosity measurements.
Limitations of linear viscoelastic models for immiscible blends assessed.
Phase inversion via zero‐shear viscosity measurements.
Cilia/flagella are whip-like, cellular appendages, widely conserved across the eukaryotes, that move a single cell through fluid, or move fluid across epithelial tissue. The flagella in the ...biflagellate alga Chlamydomonas reinhardtii are homologous to those found in humans, for example in sperm cells, and therefore, studying flagella in the algae can shed light on human disease. In this thesis, I develop a new quantitative framework for characterising flagellar activity, beginning by tracking the waveforms of C. reinhardtii flagella, and using the tracked waveforms to estimate various parameters that are relevant to flagellar beating, including frequency, amplitude, synchrony, hydrodynamic and elastic moments, curvature propagation and beat variability. These parameters have been estimated for wild-type and outer-dynein mutant flagella, as well as those immersed in a higher-viscosity medium, and for actively regrowing flagella. The results show that flagella of the mutant strain propagate weaker beats than in the wild type, while those in a raised viscosity are weaker still. For example, in a novel measure of the strength of curvature propagation, the mutant is 38% weaker, and the high-viscosity flagella 80% weaker, than the wild type. Additionally, the dynein mutant shows increased variability of the centre of force, but not the beat frequency. These results could aid with diagnosis of diseases caused by defective cilia, such as primary ciliary dyskinesia, as well as gaining further insight into the mechanisms of diseases caused by excessively viscous mucus, such as cystic fibrosis. Regrowing flagella were found to gradually recover their full-length parameters, but this increase in length was accompanied by an increase in the noise with which they beat, and a temporary aberration in the other flagellum.
Comb and bottlebrush polymers present a wide range of rheological and mechanical properties that can be controlled through their molecular characteristics, such as the backbone and side chain lengths ...as well as the number of branches per molecule or the grafting density. This review investigates the impact of these characteristics specifically on the zero shear viscosity, strain hardening behavior, and plateau shear modulus. It is shown that for a comb polymer with an entangled backbone and entangled side chains, a maximum in the strain hardening factor and minimum in the zero shear viscosity η0 can be achieved through selection of an optimum number of branches q. Bottlebrush polymers with flexible filaments and extremely low plateau shear moduli relative to linear polymers open the door for a new class of solvent‐free supersoft elastomers, where their network modulus can be controlled through both the degree of polymerization between crosslinks, nx, and the length of the side chains, nsc, with GBB0≈ρkTnx−1(nsc+1)−1.
Comb and bottlebrush polymers exhibit unusual rheological properties compared to their linear analogs due to side‐chain crowding. Investigation of the melt rheology of model branched polymers with controlled grafting density, side chain, and backbone lengths allows correlation of macroscopic flow properties such as zero shear viscosity, plateau modulus, and strain‐hardening behavior to conformational regimes by means of scaling analysis and tube theory.
Temperature‐dependent viscosity is critical to decipher two profound questions in condensed matter physics, namely the glass transition and the relaxation of amorphous solids. However, direct ...measurement of viscosity over a large temperature range is extremely difficult. Here, using classical molecular dynamics (MD) simulations, we report a novel method to calculate the equilibrium viscosity of supercooled liquid both above and below the glass transition temperature (Tg) and to estimate the nonequilibrium viscosity of glass down to room temperature. Based on the shoving model, we derived an analytical formula showing that the shear viscosity in logarithmic scale changes linearly with the shear‐induced variation in shear modulus or potential energy of the glass‐forming system. The shear viscosity as a function of steady‐state potential energy of liquid under different shear strain rates can be directly calculated in MD simulations; together with its equilibrium potential energy, one can extrapolate the zero‐strain‐rate equilibrium viscosity. We verified the proposed model by reliably calculating equilibrium viscosity near Tg of four glass‐forming systems (Kob–Andersen system, silica, Cu45.5Zr45.5Al9, and silicon) with different fragilities. Furthermore, our model can estimate the nonequilibrium viscosity of glass below Tg; the upper‐bound nonequilibrium viscosity of amorphous silica and silicon at room temperature are calculated to be ~1032 and 1025 Pa·s, respectively.
Equilibrium viscosity calculated in this work for silica and Cu45.5Zr45.5Al9 in comparison with experiments in the Angell's plot.
•Crystallisation effects on the slag phase assemblage/slag viscosity are reviewed.•Newtonian/non-Newtonian flow transitions in crystallising slags are discussed.•Discrepancy in Tcv definitions is ...demonstrated; Tcv physical meaning is discussed.•An alternative and more plausible definition of Tcv is suggested and illustrated.•The differences between the characteristic temperatures of slags are demonstrated.
The crystallisation in coal ash slags plays a critical role in coal combustion and gasification. The stable operation of a boiler or entrained-flow gasifier is vitally dependent on the easy, continuous removal of combustion by-products in the form of coal ash slags. Of the factors that govern the flow of a coal ash slag in a reactor, slag viscosity is the most important. Crystallisation affects overall slag behaviour and properties, but its most pronounced effect is on slag flow characteristics. It increases slag viscosity, causes Newtonian slag flow to transition to non-Newtonian, and yields the temperature of critical viscosity. In this paper, we systematically review and analyse the complex effect of crystallisation on these three factors.
Flow harmonics (vn) of the Fourier expansion for the azimuthal distributions of hadrons are commonly employed to quantify the azimuthal anisotropy of particle production relative to the collision ...symmetry planes. While lower order Fourier coefficients (v2 and v3) are more directly related to the corresponding eccentricities of the initial state, the higher-order flow harmonics (vn>3) can be induced by a mode-coupled response to the lower-order anisotropies, in addition to a linear response to the same-order anisotropies. These higher-order flow harmonics and their linear and mode-coupled contributions can be used to more precisely constrain the initial conditions and the transport properties of the medium in theoretical models. The multiparticle azimuthal cumulant method is used to measure the linear and mode-coupled contributions in the higher-order anisotropic flow, the mode-coupled response coefficients, and the correlations of the event plane angles for charged particles as functions of centrality and transverse momentum in Au+Au collisions at nucleon-nucleon center-of-mass energy sNN= 200 GeV. The results are compared to similar LHC measurements as well as to several viscous hydrodynamic calculations with varying initial conditions.
The development of high-performance lubricants to decrease engine friction and then reduce fuel consumption remains a major challenge for oil manufacturers. Viscosity index improvers (VIIs) are ...additives used for decades to reduce the dependency of the lubricant's viscosity on temperature to maintain an acceptable lubrication in harsh conditions. Distinction between VIIs and thickeners in realistic engine conditions is of primary interest for oil manufacturers in order to optimize the formulation process. In this context, rheological studies can provide clear insights into the actual effect of such polymeric additives. The behavior of a simplified automotive lubricant is investigated at different temperatures and high pressure and high shear stress and modeling of the properties is proposed. Various polymers of different molecular weights and conformations were mixed in a hydrocracked mineral base oil. The viscosity variations with temperature, pressure, and shear stress, obtained from specific rheometers, were then represented by different models, namely, a Vogel-Fulcher-Tamman expression, a modified Williams-Landel-Ferry correlation, and a Carreau-Yasuda equation. Different rheological responses were observed and allowed the distinction between VIIs and thickeners under different temperature and pressure conditions. The hydrodynamic radii analysis provided an explanation of the rheological responses but also highlighted the limits of the Carreau-Yasuda equation when applied to VIIs. Therefore, the Zhang expression, based on the Maxwell model and applied here to low viscoelastic solutions, is proposed as an appropriate alternative.
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