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Intrinsically disordered proteins (IDPs) are prevalent participants in liquid–liquid phase separation due to their inherent potential for promoting multivalent binding. Understanding the underlying mechanisms of phase separation is challenging, as phase separation is a complex process, involving numerous molecules and various types of interactions. Here, we used a simplified coarse-grained model of IDPs to investigate the thermodynamic stability of the dense phase, conformational properties of IDPs, chain dynamics, and kinetic rates of forming condensates. We focused on the IDP system, in which the oppositely charged IDPs are maximally segregated, inherently possessing a high propensity for phase separation. By varying interaction strengths, salt concentrations, and temperatures, we observed that IDPs in the dense phase exhibited highly conserved conformational characteristics, which are more extended than those in the dilute phase. Although the chain motions and global conformational dynamics of IDPs in the condensates are slow due to the high viscosity, local chain flexibility at the short timescales is largely preserved with respect to that at the free state. Strikingly, we observed a non-monotonic relationship between interaction strengths and kinetic rates for forming condensates. As strong interactions of IDPs result in high stable condensates, our results suggest that the thermodynamics and kinetics of phase separation are decoupled and optimized by the speed-stability balance through underlying molecular interactions. Our findings contribute to the molecular-level understanding of phase separation and offer valuable insights into the developments of engineering strategies for precise regulation of biomolecular condensates. [ABSTRACT FROM AUTHOR]

Within the low-frequency limit, this work analyzes the viscous absorbing properties of circular clusters and semi-infinite slabs made of rigid scatterers embedded in a fluid, such as air or water. These structures are made of rigid scatterers distributed in a hexagonal lattice, and they are proposed as useful absorbing devices in the core of acoustic black holes or acoustic metasurfaces. It is demonstrated that in both types of structures, an optimum value of the filling fraction produces the maximum absorption in a given frequency band. To avoid heavy numerical simulations, the broadband absorbing power has been obtained using a homogenization theory providing not only the effective acoustic parameters (effective mass and effective sound speed) but also the decay coefficient due to viscosity. An enhancement of the broadband sound absorption can be obtained by using a refractive index gradient allowing an increase of the acoustic energy into the semi-infinite slabs. The theoretical predictions are well supported by numerical simulations based on the finite-element and boundary-element methods, respectively, for the semi-infinite slabs and clusters. These predictions have potential applications in the design of structures and metasurfaces with enhanced absorbing power at low frequencies. The analytical model is further supported by experiments made with a 3D-printed sample. [ABSTRACT FROM AUTHOR]

In this study, we performed a numerical investigation of the thermophysical properties of liquid (U, Zr) mixtures, which are particularly relevant in the context of hypothetical nuclear accidents and the formation of in-vessel coriums. To do so, atomistic simulations leveraging classical molecular dynamics and an interatomic potential developed for solid (U, Zr) structures are performed. Our methodology is first validated by comparing the predictions of our model for the melting temperature and the structure factors to experimental, phase diagram, and ab initio data. We then use the approach to evaluate the temperature and composition dependence of four fundamental properties in the context of coriums: density, heat capacity, compressibility, and viscosity. Systematic comparisons to the existing experimental data are performed and discussed. In particular, the viscosity of liquid (U, Zr) mixtures is investigated by comparing diffusion calculations and the Stokes–Einstein formula as well as the results obtained with the Green–Kubo methodology, empirical predictions, and experimental data. Notably, the viscosity of the mixtures is predicted to be significantly higher than that of the single-element liquids, which is unexpected and could have crucial consequences on the early stages of the formation and flow of in-vessel corium. [ABSTRACT FROM AUTHOR]

The superadiabatic dynamical density functional theory (superadiabatic-DDFT) is a promising new method for the study of colloidal systems out-of-equilibrium. Within this approach, the viscous forces arising from interparticle interactions are accounted for in a natural way by explicitly treating the dynamics of the two-body correlations. For bulk systems subject to spatially homogeneous shear, we use the superadiabatic-DDFT framework to calculate the steady-state pair distribution function and the corresponding viscosity for low values of the shear-rate. We then consider a variant of the central approximation underlying this superadiabatic theory and obtain an inhomogeneous generalization of a rheological bulk theory due to Russel and Gast. This paper thus establishes for the first time a connection between DDFT approaches, formulated to treat inhomogeneous systems, and existing work addressing nonequilibrium microstructure and rheology in bulk colloidal suspensions. [ABSTRACT FROM AUTHOR]

The precise determination of surface transport coefficients at liquid interfaces is critical to an array of processes, ranging from atmospheric chemistry to catalysis. Building on our prior results that highlighted the emergence of a greatly reduced surface viscosity in simple liquids via the dispersion relation of surface excitations [Malgaretti et al., J. Chem. Phys. 158, 114705 (2023)], this work introduces a different approach to directly measure surface viscosity. We use modified Green–Kubo relations suitable for inhomogeneous systems to accurately quantify viscosity contributions from fluid slabs of variable thickness through extensive molecular dynamics simulations. This approach distinguishes the viscosity effects of the surface layer vs the bulk, offering an independent measure of surface viscosity and providing a more detailed understanding of interfacial dynamics and its transport coefficients. [ABSTRACT FROM AUTHOR]

This paper reports on the effects of shear rate and interface modeling parameters on the hydrodynamic slip length (LS) for water–graphite interfaces calculated using non-equilibrium molecular dynamics. Five distinct non-bonded solid–liquid interaction parameters were considered to assess their impact on LS. The interfacial force field derivations included sophisticated electronic structure calculation-informed and empirically determined parameters. All interface models exhibited a similar and bimodal LS response when varying the applied shear rate. LS in the low shear rate regime (LSR) is in good agreement with previous calculations obtained through equilibrium molecular dynamics. As the shear rate increases, LS sharply increases and asymptotes to a constant value in the high shear regime (HSR). It is noteworthy that LS in both the LSR and HSR can be characterized by the density depletion length, whereas solid–liquid adhesion metrics failed to do so. For all interface models, LHSR calculations were, on average, ∼28% greater than LLSR, and this slip jump was confirmed using the SPC/E and TIP4P/2005 water models. To address the LS transition from the LSR to the HSR, the viscosity of water and the interfacial friction coefficient were investigated. It was observed that in the LSR, the viscosity and friction coefficient decreased at a similar rate, while in the LSR-to-HSR transition, the friction coefficient decreased at a faster rate than the shear viscosity until they reached a new equilibrium, hence explaining the LS-bimodal behavior. This study provides valuable insights into the interplay between interface modeling parameters, shear rate, and rheological properties in understanding hydrodynamic slip behavior. [ABSTRACT FROM AUTHOR]

We numerically investigate the dynamics and linear rheology of disordered systems made of patchy particles, focusing on the role of valence, temperature, and bonding mechanism. We demonstrate that the dynamics is enslaved to bonding, giving rise to an activated behavior at low temperatures. By independently computing the diffusion constant and the viscosity from the simulations, we also confirm the validity of the Stokes–Einstein relation in valence-limited systems, with two caveats: (i) the diffusion constant requires a finite-size correction, at least at the intermediate density we investigate, and (ii) there is the onset of a breakdown that appears at the lowest temperatures considered. Finally, our results show that the storage and loss moduli of mixtures of divalent and M-valent particles exhibit an apparent power-law dependence on frequency, hinting at the possibility of using the composition to finely tune the rheological response of these materials. Our results compare well with literature experimental data on valence-limited DNA nanostars. In addition, the wealth of data we present and analyze here will help develop and test theoretical frameworks aimed at describing the dynamics of flexible limited-valence particles that self-assemble into disordered networks. [ABSTRACT FROM AUTHOR]

Accurate prediction of the entrained liquid droplet fraction in an annular two-phase flow regime plays a crucial role for estimating the dryout type critical heat flux to identify the optimized flow characteristics in the thermal systems across different industries. Existing studies have provided different correlations based on the limited experimental data. However, these correlations are applicable to certain operating conditions. Therefore, the present study aims at applying a deep learning method, specifically an artificial neural network (ANN), to enhance the prediction of the entrained liquid droplet fraction. Experimental data from various works on annular flow, covering a wide spectrum of pressure and flow conditions, are utilized for training the ANN model. Eight input variables, viz, superficial gas velocity (J S G ), superficial liquid velocity (J S L ), gas viscosity (μ G), liquid viscosity (μ L), gas density (ρ G), liquid density (ρ L), pipe diameter (d) and liquid surface tension (σ L V ) are considered as input features. The entrained liquid droplet fraction is the single output feature. The present model employs the Bayesian regularization backpropagation algorithm for training. The present ANN model is compared against the performance of linear regression, decision tree and support vector machine algorithms, and found that the performance of the present Bayesian regularization neural network (BRNN) model is superior within ∼ 7.5 % deviation. Further, the BRNN model is coupled with the film mass flow rate model to obtain the axial variation of the liquid film mass flow rate and good agreement is noticed when compared against the experimental data. [ABSTRACT FROM AUTHOR]

It is shown that the transport coefficients (self-diffusion, shear viscosity, and thermal conductivity) of the Weeks–Chandler–Andersen (WCA) fluid along isotherms exhibit a freezing density scaling (FDS). The functional form of this FDS is essentially the same or closely related to those in the Lennard-Jones fluid, hard-sphere fluid, and some liquefied noble gases. This proves that this FDS represents a quasi-universal corresponding state principle for simple classical fluids with steep interactions. Some related aspects, such as a Stokes–Einstein relation without a hydrodynamic diameter and gas-to-liquid dynamical crossover, are briefly discussed. Simple fitting formulas for the transport coefficients of the dense WCA fluid are suggested. [ABSTRACT FROM AUTHOR]

Shale gas reservoirs generally have ultra-low water saturation, and the water in reservoirs is closely bound to the walls of inorganic nanopores, forming a water film structure on the hydrophilic surface. When shale gas enters the inorganic nanopores, the water films in the inorganic pores will be removed by evaporation instead of being driven away by the gas, which increases the difficulty of predicting production during shale gas extraction. Based on molecular dynamics simulations, a water film evaporation model is proposed, considering the evaporation of water films during shale gas transport and the influence of water film evaporation on the shale gas transport mechanism. The Green–Kubo method is employed to calculate the viscosity of the water film. The evaporation flux of the water film under the influence of viscosity is discussed in the evaporation model. The transport mechanisms of shale gas in nanopores and the effect of water film evaporation on shale gas transport mechanisms are analyzed in detail. The result indicates that the water films in the inorganic nanopores are constrained on the hydrophilic surface, and the viscosity normal to the surface of the water film of 4 Å is 0.005 26 Pa⋅S, which is 6.12 times the reference value of viscosity at 298 K. In the process of water film evaporation, the evaporation flux of the water film is influenced by viscosity. In the study of the shale gas transport mechanism, water films in inorganic nanopores can hinder the surface diffusion of the methane molecules adsorbed on boundary and significantly reduce the mass flux of shale gas. [ABSTRACT FROM AUTHOR]

In this study, we use molecular dynamics simulations of liquid water to investigate how shear thinning affects the viscosity of liquid water by structural changes of the hydrogen bond network. The effect of shear on viscosity can be divided into two parts: shear-induced destruction of the hydrogen bond network and the influence of the water structure on shear viscosity. First, strong shear destroys tetrahedral structures and thus reduces the connectivity of the hydrogen bond network. It is mainly because shear deformation, characterized by compression and expansion axes, respectively, triggers the destruction and formation of hydrogen bonds, resulting in anisotropic effects on water structures. At the same time, shear destroys large clusters and enhances the formation of small ones, resulting in a decrease in average cluster sizes. Second, the change of viscosity obeys a power law relationship with the change of hydrogen bond structures, highlighting a one-to-one correspondence between structure and property. Meanwhile, in order to explain why the structure affects viscosity, we define hydrogen-bond viscosity and find that the cooperative motion of the water structures can promote momentum transfer in the form of aggregations. Hydrogen-bond viscosity accounts for 5%–50% of the total viscosity. Our results elucidate that water structures are the important structural units to explain the change of water properties. [ABSTRACT FROM AUTHOR]

The chemical composition and physical properties of secondary organic aerosol (SOA) generated through OH-initiated oxidation of mixtures containing β-myrcene, an acyclic monoterpene, and d-limonene, a cyclic monoterpene, were investigated to assess the extent of the chemical interactions between their oxidation products. The SOA samples were prepared in an environmental smog chamber, and their composition was analyzed offline using ultraperformance liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry (UPLC-ESI-HRMS). Our results suggested that SOA containing β-myrcene showed a higher proportion of oligomeric compounds with low volatility compared to that of SOA from d-limonene. The formula distribution and signal intensities of the mixed SOA could be accurately predicted by a linear combination of the mass spectra of the SOA from individual precursors. Effects of cross-reactions were observed in the distribution of isomeric oxidation products within the mixed SOA, as made evident by chromatographic analysis. On the whole, β-myrcene and d-limonene appear to undergo oxidation by OH largely independently from each other, with only subtle effects from cross-reactions influencing the yields of specific oxidation products.

The ice surface is known for presenting a very small kinetic friction coefficient, but the origin of this property remains highly controversial to date. In this work, we revisit recent computer simulations of ice sliding on atomically smooth substrates, using newly calculated bulk viscosities for the TIP4P/ice water model. The results show that spontaneously formed premelting films in static conditions exhibit an effective viscosity that is about twice the bulk viscosity. However, upon approaching sliding speeds in the order of m/s, the shear rate becomes very large, and the viscosities decrease by several orders of magnitude. This shows that premelting films can act as an efficient lubrication layer despite their small thickness and illustrates an interesting interplay between confinement enhanced viscosities and shear thinning. Our results suggest that the strongly thinned viscosities that operate under the high speed skating regime could largely reduce the amount of frictional heating. [ABSTRACT FROM AUTHOR]

Understanding polymer transport in nanopores is crucial for optimizing heterogeneously catalyzed processes in polymer upcycling and fabricating high-performance nanocomposite films and membranes. Although confined polymer dynamics have been extensively studied, the behavior of polyethylene (PE)—the most widely used commodity polymer—in pores smaller than 20 nm remains largely unexplored. We investigate the effects of extreme nanoconfinement on PE transport using capillary rise infiltration in silica nanoparticle packings with average pore radii ranging from ∼1 to ∼9 nm. Using in situ ellipsometry and the Lucas–Washburn model, we discover a previously unknown inverse relationship between effective viscosity (ηeff) and average pore radius (Rpore). Additonally, we determine that PE transport under these extreme conditions is primarily governed by physical confinement, rather than pore surface chemistry. We refine an existing theory to provide a generalized formalism to describe the polymer transport dynamics over a wide range of pore radii (from 1 nm and larger). Our results offer valuable insights for optimizing catalyst supports in polymer upcycling and improving infiltration processes for nanocomposite fabrication. [ABSTRACT FROM AUTHOR]

Many microorganisms propel themselves through complex media by deforming their flagella. The beat is thought to emerge from interactions between forces of the surrounding fluid, the passive elastic response from deformations of the flagellum and active forces from internal molecular motors. The beat varies in response to changes in the fluid rheology, including elasticity, but there are limited data on how systematic changes in elasticity alter the beat. This work analyses a related problem with fixed-strength driving force: the emergence of beating of an elastic planar filament driven by a follower force at the tip of a viscoelastic fluid. This analysis examines how the onset of oscillations depends on the strength of the force and viscoelastic parameters. Compared to a Newtonian fluid, it takes more force to induce the instability in viscoelastic fluids, and the frequency of the oscillation is higher. The linear analysis predicts that the frequency increases with the fluid relaxation time. Using numerical simulations, the model predictions are compared with experimental data on frequency changes in the bi-flagellated alga Chlamydomonas reinhardtii. The model shows the same trends in response to changes in both fluid viscosity and Deborah number and thus provides a possible mechanistic understanding of the experimental observations.

We report measurements of the shear viscosity η in water up to 150 MPa and down to 229.5 K. This corresponds to more than 30 K supercooling below the melting line. The temperature dependence is non-Arrhenius at all pressures, but its functional form at 0.1 MPa is qualitatively different from that at all pressures above 20 MPa. The pressure dependence is non-monotonic, with a pressure-induced decrease of viscosity by more than 50% at low temperature. Combining our data with literature data on the self-diffusion coefficient Ds of water, we check the Stokes-Einstein relation which, based on hydrodynamics, predicts constancy of Dsη/T, where T is the temperature. The observed temperature and pressure dependence of Dsη/T is analogous to that obtained in simulations of a realistic water model. This analogy suggests that our data are compatible with the existence of a liquid-liquid critical point at positive pressure in water. [ABSTRACT FROM AUTHOR]

Water is a unique and abundant substance in biological and chemical systems. Considering its importance and ubiquity, numerous water models have been developed to reproduce various properties of bulk water in molecular simulations. Therefore, selecting an appropriate water model suitable for the properties of interest is crucial for computational studies of water systems. The four-point Optimal Point Charge (OPC) and three-point OPC (OPC3) water models were developed in 2014 and 2016, respectively. These models reproduce numerous properties of bulk water with high accuracy, such as density, dielectric constant, heat of vaporization, self-diffusion coefficient, and surface tension. In this study, we evaluated the shear viscosities of the OPC and OPC3 water models at various temperatures ranging from 273 to 373 K using the Green–Kubo formalism to assess their performance. The evaluated viscosities of both models were very close to each other at all the examined temperatures. At temperatures above 310 K, the calculated shear viscosities were in excellent agreement with the experimental results. However, at lower temperatures, the water models systematically underestimated the shear viscosity, with the calculated values at 273 and 298 K being 20% and 10% lower than the experimental values, respectively. Despite this limitation, the OPC and OPC3 water models outperformed other widely used water models. [ABSTRACT FROM AUTHOR]

Understanding factors that affect the clustering and association of antibodies molecules in solution is critical to their development as therapeutics. For 19 different monoclonal antibody (mAb) solutions, we measured the viscosities, the second virial coefficients, the Kirkwood-Buff integrals, and the cluster distributions of the antibody molecules as functions of protein concentration. Solutions were modeled using the statistical-physics Wertheim liquid-solution theory, representing antibodies as Y-shaped molecular structures of seven beads each. We found that high-viscosity solutions result from more antibody molecules per cluster. Multi-body properties such as viscosity are well predicted experimentally by the 2-body Kirkwood-Buff quantity, G22, but not by the second virial coefficient, B22, and well-predicted theoretically from the Wertheim protein-protein sticking energy. Weakly interacting antibodies are rate-limited by nucleation; strongly interacting ones by propagation. This approach gives a way to relate micro to macro properties of solutions of associating proteins.

We study the zero dissipation limit problem for the Navier-Stokes equations of one-dimensional compressible viscous heat-conducting fluids. We prove that if the solution of the inviscid Euler system is piecewise smooth with a 1-shock and a 3-shock issuing from the same point, there exists a family of smooth solutions to the compressible Navier-Stokes equations which converges to the inviscid solution away from the shock discontinuities at a rate of ε η , ∀ η ∈ (0 , 1 2) as the viscosity ε tends to zero, provided that the heat-conducting coefficient κ = O (ε). Different from the result in [19] , which only holds on [ 0 , T − h ] for ∀ h > 0 , here we can prove it holds on the whole time interval [ 0 , T ] for the existence of the inviscid solution. [ABSTRACT FROM AUTHOR]

Smelting and fiberization of red mud (RM) is an attractive approach for rapid recovery of metal resources, production of mineral wool, and immobilization of hazardous alkalis. However, an enormous challenge remains in understanding alkali immobilization behavior in mineral wool over a broad A/S (Al 2 O 3 to SiO 2 mass ratio) range. Here we addressed the challenge through molecular dynamics, thermodynamic and experimental analyses. Increasing A/S ratio caused an increasing degree of structural order and the remarkable micro-phase separation occurred at A/S > 0.9. The role of Na+ and Ca2+ changed from the network-modifying cations to the charge-compensating cations. Melt viscosity decreased and then increased significantly with an intensified temperature sensitivity, identified by the increasing viscous flow activation energy from 211.5 to 377.03 kJ/mol in the temperature region from 1500 to 1570 °C. The transformation of thermodynamic properties (real mixed/excess molar Gibbs free energies, and entropy increment) corresponded to the structural changes. Thermal, mechanical and leaching tests confirmed the negative effect of this structural transformation on alkali immobilization. The A/S ratios controlled below 0.9 were proposed for environmental benefits and product stability. The investigation of immobilization mechanism provides valuable information for tuning the vitrification chemistry and developing safe and green mineral wool from RM. [Display omitted] [ABSTRACT FROM AUTHOR]

The slag-metal reaction between traditional CaO-SiO 2 -CaF 2 -Na 2 O-based slag and high-titanium steel deteriorates the performance of the mold flux, negatively affecting the surface quality of the slab and causing issues in continuous casting. To maintain the stability of slag properties after the slag-metal interaction, BaO and Li 2 O were added to the mold flux as a potential new slag system of the BaO-CaO-SiO 2 -TiO 2 -CaF 2 -Li 2 O-Na 2 O seven-component slag for the continuous casting of high titanium steel. In this study, the effects of the BaO/CaO ratio on the structure and properties of the seven-component slag were examined using molecular dynamics simulation and Raman spectroscopy, and the effect of the BaO content on the amphoteric behavior of TiO 2 was also investigated. With the gradual substitution of CaO by BaO, the melt's basicity increases, and TiO 2 transforms from acidic TiⅤ to alkaline TiⅥ. Simultaneously, the addition of BaO promotes the conversion of O b into O f and O nb , resulting in a simplified melt structure. The continuous increase in content of structural units Q Si 0 and Q Si 1 , along with the continuous decrease in content of Q Si 3 and Q Si 4 , further elucidates this phenomenon. Hence, it can be inferred that BaO primarily functions as a depolymerizing agent within the network structure of the melt. [ABSTRACT FROM AUTHOR]

For successful 3D printing based on stereolithography technologies, one of the most important factors influencing the success of printing is the dynamic viscosity of the prepared suspension. For the purposes of viscosity prediction at different volume fillings, two ZrO 2 powders with different yttrium content (CY3Z-RS and CY8Z-RS) with volume filling 0–40 % in two different dispersing mediums at two temperatures were investigated in this paper. The dependence of relative viscosity on volumetric filling was fitted by existing models and a new semi-empirical model based on experimental data was proposed and successfully plotted. Fitted data for all zirconia photosensitive suspensions showed a high correlation to the proposed model (R 2 from 97.02 % to 99.61 %). The model in addition to the possibilities of mathematical generalization of his prescription, introduces a fitting parameter C , which is thought to be thermodynamically influenceable and predictable. Furthermore, another key characteristic that is often neglected in rheological characterization, the stability of prepared ceramic suspensions, was verified either by rheological measurements but also by employing prospective technology based on analytical centrifuge. It was confirmed that all prepared suspensions were highly stable, and all instability indexes reached values less than 0.05. [ABSTRACT FROM AUTHOR]

To improve the oxidation and ablation resistance of SiC f /SiC composites, the as-synthesized ultrafine HfB 2 powder was used as the modification phase to fabricate SiC f /SiC-HfB 2 composites, and their oxidation and ablation behaviors were investigated. Compared with the unmodified SiC f /SiC composites, the oxidation resistance at 800–1500 °C and the ultra-high temperature ablation resistance of SiC f /SiC-HfB 2 composites were significantly improved. After oxidation, a compact compound glass scale consisting of HfO 2 , HfSiO 4 and Si-Hf-O glass was formed, providing the effective oxidation protection. A dual-phase oxide scale composed of HfO 2 skeleton and Si-Hf-O glass was formed after ablation, exhibiting the high viscosity, the significant oxygen-blocking effect and resistance to gas flow scouring. The improved oxidation and ablation resistance of SiC f /SiC-HfB 2 composites could be attributed to the effective protective role of oxygen-blocking scales formed during the oxidation and ablation processes. [ABSTRACT FROM AUTHOR]

In this paper, we study the asymptotic expansion for the homogeneous model of wind‐driven oceanic circulation with the nonslip boundary condition when both of the beta‐plane parameter and the Reynolds number go to infinity. By asymptotic analysis under certain constraints on wind tensor, we derive a formal expansion including the geophysical boundary layer in the large beta‐plane parameter and high Reynolds number limit, from which one sees that the external force, wind tensor, has an important effect on the behavior of the boundary layers. Moreover, when the external force and initial data satisfy certain constraints, to exclude the appearance of strong boundary layers, we construct approximate solutions with steady boundary layers to the homogeneous model of wind‐driven oceanic circulation in the large beta‐plane parameter and high Reynolds number limit. By using an energy method, we obtain the L∞$$ {L}^{\infty } $$‐stability of small perturbation around this approximate solutions, which verifies the validity of the asymptotic expansion of weak boundary layers in the large beta‐plane parameter and high Reynolds number limit. [ABSTRACT FROM AUTHOR]

Geopolymers represent a distinct class of materials characterised by their X-ray amorphous nature and nanoporous, nanoparticulate structure. Geopolymers can be conveniently mixed, poured, and cured under ambient conditions. This makes this class of materials an interesting alternative to ordinary Portland cement for structural processes. Additionally, the addition of alumina can improve mechanical properties, while the addition of glass can form an impermeable glaze which could be useful for molten salt containment. Therefore, in this investigation, potassium metakaolin-based geopolymer composites with varying proportions of glass particles and alumina platelets were fabricated, cured, heat-treated, and analyzed to study the effects of composition on material properties. Various attributes including rheological properties, densities, mass loss, shrinkage, and porosities were compared. It was observed that certain compositions exhibited high viscosities, making high shear mixing challenging, while also displaying significant permeability that would hinder their ability to contain liquids without leakage. Additionally, certain samples showed reduced densities, suggesting potentially weaker mechanical properties; however, the investigation did not include a direct assessment of mechanical properties. The most promising candidates for containing liquids at high temperature contained 50 wt% KGP, 25 or 35 wt% glass powder, and 25 or 15 wt% alumina platelets, respectively. ASH-G slurries required a minimum of 65 vol% KGP to produce a homogenous material compatible with additive manufacturing. The minimum amount of glass phase to form surface glazes was 16 vol%. Only samples containing more glass phase than alumina phase produced glazed composites. [ABSTRACT FROM AUTHOR]

Digital light processing technology has the advantages of high molding accuracy and the ability to prepare complex structures, which is commonly used in the preparation of resin or ceramics. By mixing two particle sizes of zirconia powders, this paper successfully prepared a 60 vol% slurry with a low viscosity of 1.28 Pa s at shear rate was 50 s−1. By systematically studying the rheological properties of the mixed slurry, the curing depth was exceeding 100 μm at exposure time of 3 s. Furthermore, by investigating the debinding process of the printed sample, it is found that the sintering sample after debinding in vacuum has the highest density. This work has a positive significance for the preparation and debinding process of high solid loading ceramic slurry. [ABSTRACT FROM AUTHOR]

Fluid viscosity and osmolarity are among some of the underappreciated mechanical stimuli that cells can detect. Abnormal changes of multiple fluidic factors such as viscosity and osmolarity have been linked with diseases such as cystic fibrosis, cancer, and coronary heart disease. Changes in viscosity have been recently suggested as a regulator of cell locomotion. These novel studies focus on cell migration and spreading on glass substrates and through microchannels, and it remains a question whether viscosity impacts the cellular remodeling of extracellular matrices (ECMs). Here, we demonstrate that elevated viscosity induces cellular remodeling of collagen substrates and enhances cell spreading on ECM‐mimetic substrates. Our results expand on recent work showing that viscosity induces increased cellular forces and demonstrates that viscosity can drive local ECM densification. Our data further show that microtubules, Ras‐related C3 botulinum toxin substrate 1 (Rac1), actin‐related protein 2/3 (Arp2/3) complex, Rho‐associated protein kinase 1 (ROCK), and myosin are important regulators of viscosity‐induced ECM remodeling. In the context of viscosity‐induced cell spreading, cells cultured on glass and collagen substrates exhibit markedly different responses to pharmacological treatments, indicating that microtubules, Rac1, and Arp2/3 play distinct roles in regulating cellular spreading depending on the substrate. In addition, our results demonstrate that high osmotic pressures override viscosity‐induced cell spreading by suppressing membrane ruffling. Our results demonstrate viscosity as a regulator of ECM remodeling and cell spreading in a fibrillar microenvironment. We also reveal a complex interplay between viscosity and osmolarity. We anticipate that our research can pave the way for future investigations into the crucial roles played by viscosity in both physiological and pathological conditions. [ABSTRACT FROM AUTHOR]

This article considers the zero‐pressure gas dynamics governed by the conservation laws of mass, momentum, and energy with time‐dependent source terms. By adopting the vanishing viscosity method, we propose a viscous system to prove the stability of non‐self‐similar Riemann solutions including the delta shock wave and vacuum. [ABSTRACT FROM AUTHOR]

Acrylamide polymers are typically used in industrial and healthcare sectors as thickening agents; however, their thickening capabilities rely mainly in their molecular mass. A versatile and simple strategy to improve their performance is the copolymerization with specific monomers or their chemical modification with structures like dendritic or hyperbranched molecules. This study introduces a novel acrylamide‐acrylic acid polymer grafted with minor proportions (≤4.0 wt%) of Boltorn H30, a hyperbranched polyester monomer. The incorporation of Boltorn H30 aims to exploit the hyperbranched architecture's impact on the viscosity and rheological behavior of polymer solutions. Polymers with 0.4 and 4.0 polyester wt% characterized by several analytical techniques displayed improved viscosity in aqueous solution compared against the parent poly(acrylamide‐co‐acrylic acid). Results revealed that while the molecular mass distribution changed between 20% and 94%, the thickening capabilities significantly improved with increments of 2.7 and 3.8 times compared to that of the original polymers. These findings demonstrate that even with a minimal incorporation of hyperbranched polyesters, the abundance of hydroxyl groups fosters extensive hydrogen bonding, resulting in enhanced viscosity properties of the polymer. [ABSTRACT FROM AUTHOR]

We propose a simple, efficient, and reliable procedure for implicit time stepping, regarding a special case of the viscoplasticity model proposed by Simo and Miehe (1992). The kinematics of this popular model is based on the multiplicative decomposition of the deformation gradient tensor, allowing for a combination of Newtonian viscosity and arbitrary isotropic hyperelasticity. The algorithm is based on approximation of precomputed solutions. Both Lagrangian and Eulerian versions of the algorithm with equivalent properties are available. The proposed numerical scheme is non‐iterative, unconditionally stable, and first order accurate. Moreover, the integration algorithm strictly preserves the inelastic incompressibility constraint, symmetry, positive definiteness, and w‐invariance. The accuracy of stress calculations is verified in a series of numerical tests, including non‐proportional loading and large strain increments. In terms of stress calculation accuracy, the proposed algorithm is equivalent to the implicit Euler method with strict inelastic incompressibility. The algorithm is implemented into MSC.MARC and a demonstration initial‐boundary value problem is solved. [ABSTRACT FROM AUTHOR]

ABSTRACT In the context of numerical simulators for multiphase flow in porous media, there exists a long‐standing issue known as the grid orientation effect (GOE), wherein different numerical solutions can be obtained when considering grids with different orientations under certain unfavorable conditions. The GOE is relevant to the instability near displacement fronts. If numerical oscillations accompanied by sharp fronts are not adequately suppressed, the GOE occurs. To reduce or even eliminate the GOE, we propose augmenting adaptive artificial viscosity in the process of solving the saturation equation. It has been demonstrated that appropriate artificial viscosity can effectively reduce or even eliminate the GOE. The proposed numerical method can be easily applied in practical engineering problems. [ABSTRACT FROM AUTHOR]

A series of donor‐acceptor (D–π–A) substituted diphenylbutadienes exhibiting solvatochromic emission and a large Stokes shift (100–200 nm) were designed and synthesized for distinctive organelle labelling, enabling real‐time monitoring of organelle behaviour such as lysosomal dynamics, mitophagy monitoring, and stress responses. The morpholine‐substituted D–A–D diphenylbutadiene (M2) was employed to investigate selective imaging of lysosomes, the uptake of damaged mitochondria through mitophagy, and monitoring lysosomal viscosity or pH changes. Other diphenylbutadiene derivatives (M1, M3, M4) selectively accumulated in lipid droplets. All the synthesized derivatives demonstrated significant uptake in 5‐day post‐fertilization zebrafish larvae, with M2 showing maximum uptake in the enterocyte‐containing heart and intestinal regions, which include the lysosomes. [ABSTRACT FROM AUTHOR]

Upconverting particles (UCPs), renowned for their capability to convert infrared to visible light, serve as invaluable imaging probes. Furthermore, their responsiveness to diverse external stimuli holds promise for leveraging UCPs as remote multiparametric sensors, capable of characterizing medium properties in a single assessment. However, the utility of UCPs in multiparametric sensing is impeded by crosstalk, wherein distinct external stimuli induce identical alterations in UCP luminescence, hindering accurate interpretation, and yielding erroneous outputs. Overcoming crosstalk requires alternative strategies in upconverting luminescence analysis. In this study, it is shown how a single spinning NaYF4:Er3+, Yb3+ upconverting particle enables simultaneous and independent readings of temperature and viscosity. This is achieved by decoupling thermal and rehological measurements—employing the luminescence of thermally‐coupled energy levels of Er3+ ions for thermal sensing, while leveraging the polarization of luminescence from non‐thermally coupled levels of Er3+ ions to determine viscosity. Through simple proof‐of‐concept experiments, the study validates the capability of a single spinning UCP to perform unbiased, simultaneous temperature, and viscosity sensing, thereby opening new avenues for advanced sensing in microenvironments. [ABSTRACT FROM AUTHOR]

We study the stability and convergence properties of a semi-implicit time stepping scheme for the incompressible Navier–Stokes equations with variable density and viscosity. The density is assumed to be approximated in a way that conserves the minimum-maximum principle. The scheme uses a fractional time-stepping method and the momentum, which is equal to the product of the density and velocity, as a primary unknown. The semi-implicit algorithm for the coupled momentum-pressure is shown to be conditionally stable and the velocity is shown to converge in L 2 norm with order one in time. Numerical illustrations confirm that the algorithm is stable and convergent under classic CFL condition even for sharp density profiles. [ABSTRACT FROM AUTHOR]

Diamond-like carbon (DLC)/poly-α-olefin (PAO) composite system attracts much attention in reducing the tribo-induced risks for mechanical mobility systems and energy saving. However, the coupled effect of applied load and PAO viscosity on the tribological behavior of the DLC/PAO system, which normally causes the transition between different lubrication states of mated surfaces, and the corresponding synergistic mechanism remain unclear. Here, we fabricated the DLC/PAO composite system, and the evolutions of microstructure, morphologies, and tribological properties induced by both PAO viscosity and applied load were investigated systematically. Results indicated that under low applied load, the system with moderate PAO viscosity exhibited the best tribological performance, while the PAO with high viscosity was suggested with increasing the applied load. Moreover, the variations of PAO viscosity and applied load seriously affected the distribution and load-bearing capacity of oil, interfacial graphitization degree, and formation of lubricating oil film, which brought complicated effects on the tribological properties of composite systems. The present results guide the selection and design of an advanced DLC/PAO lubrication system according to the working conditions. [ABSTRACT FROM AUTHOR]

In this article, we investigate the Rayleigh-Taylor instability in a system of two-dimensional nonhomogeneous incompressible fluid equations with Coriolis force and partial viscosity. First, we employ variational methods to construct linear unstable solutions to the corresponding linearized equations of the system. Second, we utilize the classical Osgood lemma to derive nonlinear energy estimates for the perturbed equations. The local existence of solutions to the perturbed equations is established by using the semi-Galerkin method and the expanding domain method. Finally, we prove the nonlinear instability by combining the properties of the linear unstable solutions and the nonlinear energy estimates. [ABSTRACT FROM AUTHOR]

In this work, a power law f(Q)$f(Q)$ model is explored, specifically, f(Q)=αQn$f(Q)= \alpha Q^n$, along with viscous matter fluid having transport coefficient ζ=ζ0Ω+ζ1ΩH$\zeta = \zeta _0 \sqrt {\Omega } + \zeta _1 \Omega H$. The corresponding analytical solution is derived and then confronted with recent cosmic data. The Markov Chain Monte Carlo (MCMC) sampling technique is utilized to estimate the mean value of arbitrary parameters, by incorporating Cosmic Chronometers and recently published Pantheon+Analysis samples. In addition, some cosmological parameters are reconstructed by resampling the chains obtained by emcee, incorporating 6000 samples. It is found that the matter‐energy density depicts the expected positive behavior, whereas the effective pressure indicates the negative behavior that is leading the accelerating expansion, which is further predicted in the effective EoS parameter. Further, the asymptotic nature of the assumed model is investigated by invoking phase‐space analysis. It is concluded that the assumed viscous f(Q)$f(Q)$ model successfully predicts an evolution of the universe from decelerated epoch to stable accelerated de‐Sitter epoch. [ABSTRACT FROM AUTHOR]

The complexity of the chocolate matrix leads to it having characteristic rheological properties that may pose difficulties for its industrial manufacture. Many factors influence the flow behaviour of chocolates, such as raw materials, the amount of fat, the moisture content, particle-size distribution, the concentration of emulsifiers, or manufacturing conditions, among others. This study focusses on the rheological properties of an industrially manufactured chocolate with a 48% cocoa content, and the effect caused by the addition of two emulsifiers (soya lecithin and polyglycerol polyricinoleate (PGPR)) on the rheological properties. In the case of lecithin, a clear effect has been observed on the plastic viscosity and the yield stress. Plastic viscosity decreases until a concentration of 0.6% lecithin is reached, and thereafter remains relatively constant, while yield stress increases over the studied range. This effect is not observed when PGPR is used as the emulsifying agent. In this case, a small concentration of PGPR decreases the yield stress. Thixotropy was determined using the Casson model, and its behaviour was found to be similar to that of plastic viscosity with respect to changes in the PGPR and lecithin concentrations. Textural determinations were also carried out, relating the rheology characteristics to the texturometry. [ABSTRACT FROM AUTHOR]

The advent of recycling antibodies, leveraging pH-dependent antigen binding and optimized FcRn interaction, has advanced the field of antibody therapies, enabling extended durability and reduced dosages. Eculizumab (Soliris®) demonstrated the efficacy of C5 inhibitors for paroxysmal nocturnal hemoglobinuria (PNH), while its derivative, ravulizumab (Ultomiris®), recognized as a recycling antibody, extended the dosing intervals. However, limitations including intravenous administration and inefficacy in patients with the R885H single-nucleotide polymorphism (SNP) in C5 could necessitate alternative solutions. Crovalimab (PiaSky®), a next-generation recycling antibody, overcomes these challenges with innovative charge engineering, achieving the enhanced cellular uptake of C5–crovalimab complexes and targeting a unique C5 epitope, allowing for efficacy regardless of the R885H SNP. This study highlights crovalimab's distinctive molecular features, showing its eliminated binding to Fcγ receptors and C1q, alongside its optimized antigen binding characteristics. The impact of charge engineering was reconfirmed in mice, demonstrating faster C5 clearance than recycling antibodies. Notably, in the maintenance dosing regimen, crovalimab neutralizes approximately seven C5 molecules per antibody on average. Furthermore, its design also reduces the viscosity to facilitate high-concentration formulations suitable for subcutaneous delivery. Consequently, crovalimab offers a four-weekly subcutaneous injection regimen for PNH, marking a substantial improvement in treatment convenience and potentially transforming patients' quality of life. [ABSTRACT FROM AUTHOR]

Radiopaque polyurethanes are extensively used in biomedical fields owing to their favorable balance of properties. This research aims to investigate the influence of particle concentration on various properties, including rheological, radiopacity, structural, thermal, and mechanical attributes, with a thorough analysis. The findings are benchmarked against a commercial product (PL 8500 A) that contains 10% weight barium sulfate. Two more thermoplastic polyurethanes (TPU) were formulated with two different concentrations of barium sulfate (10 wt.% and 20 wt.%) and compared to the commercially available product. FTIR demonstrated similar absorption bands among all samples, indicating that the fabrication method did not impact the TPU matrix. DSC indicated a predominantly amorphous structure for PL 8500 A compared to the other samples, while the kinetic degradation was more influenced by the higher barium sulfate content. The rheological analysis showed a decrease in the complex viscosity and storage modulus with the radiopacifier and an increase in the radiopacity, as demonstrated by the X-radiography. X-ray microtomography showed a more spherical particle format with a heterogeneous particle structure for PL 8500 A compared to the other polyurethanes. These findings enhance the comprehension of the structure–property relationships inherent in these materials and facilitate the development of customized materials for targeted applications. [ABSTRACT FROM AUTHOR]

Hemp seed protein isolates (HPI) were used to produce a gel through probiotic fermentation. This study assessed how fermentation time (ranging from 0 to 16 h) affected the physicochemical properties of the HPI gel. The results indicated that gel formation began after 8 h of fermentation, as demonstrated by a pH decrease, an increase in particle size, and the development of aggregation observed through fluorescence and scanning electron microscopy. The gel produced after 16 h of fermentation showed the highest viscosity, storage modulus, and gel strength, attributed to stronger molecular interactions, including non-covalent and covalent crosslinking. However, the gel produced after 12 h of fermentation showed the highest water-holding capacity, and extending the fermentation beyond 12 h caused a decrease in water-holding capacity. Additionally, the subunits tended to form polymers after fermentation, suggesting that gel formation was influenced by both acidification and specific covalent crosslinking. These findings propose that HPI could serve as a viable alternative for developing plant-based gel products. [ABSTRACT FROM AUTHOR]

The present work shows the development of a comprehensive theoretical formulation for its application in the study of the internal flow of pressure-swirl atomizers with helical channels: "screw-conveyer", which are characterized by presenting in their inlet channels, an angle of incidence or helix angle ψ. This angle originates a trigonometric factor ( cos ψ ) that must be considered in the geometrical characteristics parameter of pressure-swirl atomizer ( A h ), which consequently involves other geometric parameters, such as the annular section coefficient (φ), discharge coefficient ( C d ), spray angle ( 2 α ), etc., being relevant in the internal flow study and design of the pressure-swirl atomizers type screw-conveyer. This theoretical formulation integrates an internal ideal flow model (Abramovich theory) with a model that considers the influence of the liquid viscosity (Kliachko theory) and hydraulic resistance of Idelchik. For the validation of this theoretical formulation, numerical simulation was used, considering the commercial software Ansys Fluent 2023 R2 furthermore, hexahedral meshes were generated with the ICEM CFD software 2023, for four cases of helix angle ψ ( 15 ° , 30 ° , 45 ° and 60 ° ), with application of the RNG k- ε turbulence model and VOF multiphase model (volume of fluid) for the location of the liquid-gas interface and spray angle visualization. [ABSTRACT FROM AUTHOR]

A problem has been noted regarding the admixture of fuel to a low viscosity lubricant in hybrid electric vehicles (HEVs). This is very detrimental to the wear and tear of engine operating components. In this study, the operating conditions of HEVs were analysed. Using X-ray fluorescence spectrometry (XRF), engine oils of two different viscosity classes were compared after the operating process and these data were compared with fresh reference samples. Attention was paid to the content of elements such as Ca, Zn, Mo, Sn, Cd, Fe Pb, Si, Cu, and Ni. The depletion of anti-wear additives, as well as the higher content of metallic wear products relative to the operated 5W30 (engine oil), contributed to the overall assessment of the lubricity of the 0W30 oil, as well as to the tribological results. Then, under laboratory conditions, oil samples contaminated with up to 1 to 8% fuel were subjected to rheological (mini AV-X viscometer) and tribological (four-ball tester) tests. The dependence of the local pressure at the metal-to-metal contact point in the kinematic node on viscosity showed the dissimilar nature of the used and fresh oil and the divergence of the domains for the two groups of samples. Increasing the fuel contamination of used oil above 4% drastically reduces the pressure responsible for maintaining the oil film. In order to improve lubricant performance during HEV operation in urban conditions, it was proposed to carry out extra-urban traffic driving in order to evaporate the fuel from the engine oil. A shorter oil change interval is also recommended. [ABSTRACT FROM AUTHOR]

Biosurfactants represent a promising choice for the development of environmentally friendly and gentle personal care cleansers. Building viscosity is one of the major challenges to apply biosurfactants. In this study, sodium lauroyl sarcosinate (LS) and sodium lauroamphoacetate (LA) were used as bases to build wormlike micelles, and subsequently rhamnolipids were introduced to build mild surfactant systems. The LS‐LA mixture had the highest viscosity at the mass ratio of 1:5 and pH 6.0. After adding 1 wt% and less rhamnolipid, relatively high viscosity can be maintained. The viscosity of LS‐LA‐rhamnolipid can be increased by adding NaCl and more significantly by the addition of carrageenan due to its synergistic interactions with the surfactant mixture. In addition, the foaming properties of the systems are characterized with different amounts of rhamnolipid and carrageenan, which are correlated with the bulk viscosity and interfacial elasticity of the diluted solution used for the foaming test. Rhamnolipids have both high mildness and cleaning efficacy and adding rhamnolipids can significantly increase the mildness of the system. This study offers practical solutions for the incorporation of rhamnolipids or other biosurfactants in the formulation of personal care cleansers. [ABSTRACT FROM AUTHOR]

Existing numerical methods for modeling slurry infiltration often employ a fluid continuity equation commonly used in groundwater flow analysis. However, it is essential to account for the changes in fluid density and viscosity due to shifts in slurry concentration. In view of this, a multi-field numerical model is developed to simulate the slurry infiltration in saturated soil considering the coupling relationship between particle transportation, fluid seepage, and soil deformation. The governing equations of slurry infiltration are derived based on the mass conservation law. The permeability coefficient is modified through spatiotemporal variation of slurry viscosity, which is governed by concentration modifications. The calculated results are validated using the existing test data, which rectifies the issue of non-conservation of mass in the existing model based on the continuity condition of the liquid phase. Finally, the method is applied to a model of a slurry trench to simulate the process of slurry infiltration, including the spatiotemporal variation of deposition, fluid pressure, and concentration. The time of mud cake formation is determined based on the pressure–time distribution. It is found that the time of mud cake formation in the slurry trench can be shortened by increasing the slurry concentration. [ABSTRACT FROM AUTHOR]

We offer a modern interpretation of Lagrangian hydrodynamics as employed in Lagrangian simulations of compressible fluid flow. Our main result is to show that artificial viscosity, traditionally viewed as a numerical artifice to control unphysical oscillations in flows with shocks, actually represents a physical process and is necessary to derive accurate simulations in any compressible flow. We begin by reviewing the origins of two numerical devices, artificial viscosity and finite‐volume methods. We proceed to construct a mathematical (PDE) model that incorporates those numerics and in which a new length scale, the observer, arises representing the discretization. Associated with that length scale, there are new inviscid fluxes that are the artificial viscosity as first formulated by Richtmyer and an artificial heat flux postulated by Noh but typically not included in Lagrangian codes. We discuss the connection of our results to bivelocity hydrodynamics. We conclude with some speculation as to the direction of future developments in multidimensional Lagrangian codes as computers get faster and have larger memories. [ABSTRACT FROM AUTHOR]

A series of seven new meso -phenyl BODIPY-pyrrolo[3,4- b ]pyridin-5-one conjugates were synthesized in one experimental step by using a Sc(III)-catalyzed Ugi-Zhu three-component reaction coupled to a cascade sequence (aza Diels-Alder/ N -acylation/aromatization) as post-MCR functionalization process. Further experimental studies were performed behind understanding the fluorescence response toward viscosity. All compounds exhibited a linear response between increasing viscosity (DMSO and glycerol mixtures) and fluorescence intensity. The different substituents also influenced the photophysical properties. Furthermore, in DMSO all compounds exhibited dual emission. Each band is attributed to the pyrrolo[3,4- b ]pyridin-5-one and BODIPY moieties, respectively. The electronic structure of all compounds was computed by DFT and TD-DFT calculations, allowing to determine the molecular orbitals involved in the electronic transitions. [ABSTRACT FROM AUTHOR]