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Protists, an umbrella term first coined by Ernst Haeckel in 1866, are a vast collection of (primarily unicellular) eukaryotes that are "neither animals nor plants". This basic definition by exclusion has been exercised for centuries, even though recent advances have led to more rigorous taxonomic assignment of various protist groups. Pioneering comparative phylogenetic approaches have been applied to these organisms to reconstruct the deep branches of the eukaryotic tree, revealing essential clues about early eukaryotic evolution. Protists, including amoebae, flagellates, ciliates, and algae, are also vital constituents of global ecosystems, where they appear at the base of food chains, control the relative abundance of other microbes, and participate in global biogeochemical recycling. Due to their typically small size and lack of nervous systems, protists are often associated with the unfortunate label 'primitive'. Yet they exhibit remarkable behavioural sophistication and are able to feed, predate, navigate and interact with their surroundings. Unlike macroscopic animals, many protists reside in a non-intuitive physical regime where viscous forces dominate over inertia, and where they use diverse propulsion and navigation strategies. Interdisciplinary research into these cell-scale phenomena, characterised by a complex interplay of physical forces and mechanical constraints, has significantly advanced the emerging fields of active matter, microhydrodynamics, and non-equilibrium statistical physics. This primer discusses the biophysics of protist behaviour, with a focus on locomotion and feeding. I will highlight the most extensively studied principles and describe some more esoteric behaviours that have not yet been systematically explored. Kirsty Wan discusses the biophysics of protist behaviour, with a focus on locomotion and feeding, highlighting the most extensively studied principles and describing some more esoteric behaviours that have not yet been systematically explored. [ABSTRACT FROM AUTHOR]

Because of its inherent properties, the use of thermoplastic composites is expanding in a number of industries, including aerospace, rail transportation, and wind power generation. However, the development of 2D and 3D reinforced thermoplastic composite structures is hampered by the high viscosity and poor wetting of thermoplastic matrices, resulting in their application being mainly limited to nonload‐bearing components. This article provides a comprehensive overview of the technology and current applications of thermoplastic composites, covering materials, preform structures, manufacturing methods, process parameters, performance, and applications. It also provides an outlook on their future development. Highlights: Thermoplastic composite has economic and environmental benefits.Summarized the current technology and application of thermoplastic composites.The manufacturing difficulty is the thermoplastic polymers wet fibers.One promising approach to the issue is prepreg technology.Prepreg technology make 3D thermoplastic composites become possible. [ABSTRACT FROM AUTHOR]

Microfluidic technology widely used in generating monodisperse emulsion droplets often suffers from complexity, scalability, applicability to practical fluids, as well as operation instability due to its susceptibility to flow perturbations, low clearance, and depletion of surfactants. Herein, we present a monolithic 3D-printed step-emulsification device (3D-PSD) for scalable and robust production of high viscosity emulsion droplets up to 208.16 mPa s, which cannot be fully addressed using conventional step-emulsification devices. By utilizing stereo-lithography (SLA), 24 triangular nozzles with a pair of 3D void flow distributors are integrated within the 3D-PSD to ensure uniform flow distribution followed by monodisperse droplet formation. The outlets positioned vertically downward enables gravity-assisted clearing to prevent droplet accumulation and thereby maintain size monodispersity. Deposition of silica nanoparticles (SiNP) within the device was also shown to alter the surface wettability from hydrophobic to hydrophilic, enabling the production of both water-in-oil (W/O) as well as oil-in-water (O/W) emulsion droplets, operated at a maximum production rate of up to 50 mL h−1. The utility of the device is further verified through continuous production of biodegradable polycaprolactone (PCL) microparticles using O/W emulsion as templates. We envision that the 3D-PSD presented in this work marks a significant leap in high-throughput production of high viscosity emulsion droplets as well as the particle analogs. [ABSTRACT FROM AUTHOR]

One-pot ethanol production, which involves successive biomass pretreatments, enzymatic hydrolysis, and fermentation in a single vessel, is essential for practical bioethanol production. To achieve this, low-toxicity pretreatment solvents such as a zwitterionic liquid, OE2imC3C, are necessary. Although the cellulose-dissolving ability of OE2imC3C has been studied, its biomass pretreatment ability has not been thoroughly investigated. Herein, we investigated the biomass pretreatment ability of OE2imC3C at various temperatures and concentrations. The mildest conditions for successful pretreatment were 75 wt% OE2imC3C at 90 °C. On the other hand, OE2imC3C exhibited a lower pretreatment ability than [C2mim]OAc, which is the best-known cellulose-dissolving ionic liquid. The main reason for the low pretreatment ability of OE2imC3C was its high viscosity. Reducing their viscosity is a key factor for designing zwitterionic liquids with high pretreatment ability. [ABSTRACT FROM AUTHOR]

Contactless microscale tweezers are highly effective tools for manipulating, patterning, and assembling bioparticles. However, current tweezers are limited in their ability to comprehensively manipulate bioparticles, providing only partial control over the six fundamental motions (three translational and three rotational motions). This study presents a joint subarray acoustic tweezers platform that leverages acoustic radiation force and viscous torque to control the six fundamental motions of single bioparticles. This breakthrough is significant as our manipulation mechanism allows for controlling the three translational and three rotational motions of single cells, as well as enabling complex manipulation that combines controlled translational and rotational motions. Moreover, our tweezers can gradually increase the load on an acoustically trapped cell to achieve controllable cell deformation critical for characterizing cell mechanical properties. Furthermore, our platform allows for three-dimensional (3D) imaging of bioparticles without using complex confocal microscopy by rotating bioparticles with acoustic tweezers and taking images of each orientation using a standard microscope. With these capabilities, we anticipate the JSAT platform to play a pivotal role in various applications, including 3D imaging, tissue engineering, disease diagnostics, and drug testing. The joint subarray acoustic tweezer platform offers 3D translation and rotation of bioparticles, enabling complex manipulation and cell deformation, with applications in tissue engineering, disease diagnostics, and drug testing. [ABSTRACT FROM AUTHOR]

ABSTRACT This study aims to evaluate homogenization techniques and conditions for producing stable, small droplet‐size water‐in‐oil (W/O) emulsions intended for incorporation into casein hydrolysate–loaded double emulsions. Three commonly used homogenization methods; rotor–stator, ultrasonic, and high‐pressure homogenization were individually optimized utilizing response surface methodology. Instances of over‐processing were observed, particularly with the rotor–stator and ultrasonic homogenizers under specific conditions. Nevertheless, optimal conditions were identified for each technique: 530 s at 17,800 rpm agitation speed for the rotor–stator homogenizer, 139 s at 39% amplitude for the ultrasonic homogenizer, and 520 s at 1475 bar for the high‐pressure homogenizer. Subsequently, the W/O emulsions produced under optimal conditions and their respective W1/O/W2 double emulsions were compared. The rotor–stator and high‐pressure homogenized W/O emulsions exhibited comparable narrow droplet‐size distributions, as indicated by similar Span values. However, high‐pressure homogenization failed to sufficiently minimize droplet size. Ultrasonic homogenization resulted in droplets at the 1‐μm scale but yielded more polydisperse droplet‐size distribution. According to TOPSIS analysis, an emulsion with a viscosity of 93.1 cP (centiPoise), a stability index of 93.8%, a D(90) of 0.67 μm (0th day), and a D(90) of 0.75 μm (30th day) produced using a rotor–stator was selected. Additionally, double emulsions containing primary emulsions prepared with the rotor–stator method demonstrated higher viscosity, narrower droplet‐size distribution, and lower creaming compared to other samples. This investigation sheds light on the influence of homogenization techniques on emulsion properties, providing valuable insights for optimizing double emulsion formulations. [ABSTRACT FROM AUTHOR]

The precise detection of liquid flow and viscosity is a crucial challenge in industrial processes and environmental monitoring due to the variety of liquid samples and the complex reflective properties of energetic liquids. Traditional methods often struggle to maintain accuracy under such conditions. This study addresses the complexity arising from sample diversity and the reflective properties of energetic liquids by introducing a novel model based on computer vision and deep learning. We propose the DBN-AGS-FLSS, an integrated deep learning model for high-precision, real-time liquid surface pointer detection. The model combines Deep Belief Networks (DBN), Feedback Least-Squares SVM classifiers (FLSS), and Adaptive Genetic Selectors (AGS). Enhanced by bilateral filtering and adaptive contrast enhancement algorithms, the model significantly improves image clarity and detection accuracy. The use of a feedback mechanism for reverse judgment dynamically optimizes model parameters, enhancing system accuracy and robustness. The model achieved an accuracy, precision, F1 score, and recall of 99.37%, 99.36%, 99.16%, and 99.36%, respectively, with an inference speed of only 1.5 ms/frame. Experimental results demonstrate the model's superior performance across various complex detection scenarios, validating its practicality and reliability. This study opens new avenues for industrial applications, especially in real-time monitoring and automated systems, and provides valuable reference for future advancements in computer vision-based detection technologies. [ABSTRACT FROM AUTHOR]

In this study, the molecular structure models of four ionic liquids were created, the reverse nonequilibrium molecular dynamics simulation (RNEMD) approach was used to predict their densities and viscosities, and their thermal conductivity was simulated using the non-equilibrium molecular dynamic simulation method (NEMD). The calculated results of ionic liquid densities were compared with the data in the literature; most of the variances are around 2.5%, and the maximum relative deviation was less than 6.27%; viscosity values were compared with the experimental data, with a maximum relative deviation of −8.96% and a minimum relative deviation of −2.72%. The simulated thermal conductivity has a good linear relationship with respect to temperature and pressure, which is in good agreement. This study provides a reference for molecular dynamics simulation to measure the physical properties of ionic liquids, which is important for the development of ionic liquids. [ABSTRACT FROM AUTHOR]

Three-dimensionally printed concrete is a transformative technology that addresses housing shortages due to population growth and enables innovative architectural designs. The objective of this study is to investigate the connection between a conventional test and the rheological properties of 3D-printed concrete. A more precise assessment of material quality based on traditional evaluation techniques is proposed. Standard tests are conducted to evaluate the consistency of 3D-printed concrete materials. Complementarily, a rheometer is employed to accurately measure key rheological properties, thereby establishing a link with empiric testing methodologies. The correlation between the flow table test and rheological coefficients, such as yield stress and viscosity, has been identified as the most effective in basic experiments for evaluating material behavior. This approach allows for a preliminary assessment of printability without the need for additional complex equipment. The study has successfully established a relationship between flow table tests and rheological parameters. However, further research involving a broader range of materials and print-test experiments is essential to enhance the correlation between other conventional testing methods and rheometer results. [ABSTRACT FROM AUTHOR]

Slurry feed charged into an electric melter creates a layer of reacting and melting material (termed cold cap) that floats on the surface of molten glass. The rheological behavior of heated melter feed affects the spreading of slurry at the top of the cold cap and the stability of the primary foam, affecting cold‐cap coverage and melter plenum temperatures. The apparent viscosity of a high‐alumina high‐level waste melter feed was assessed by thermomechanical analysis, high‐temperature viscometer, and the hot stage microscopy method, yielding viscosity estimates from ≈107.5 Pa s at 550°C to ≈102.5 Pa s at 1050°C. As the temperature of feed materials increased, their state changed from rigid solid to dilatant fluid, to pseudoplastic bubbly liquid with dissolving solids, to fully developed foam, and finally to Newtonian glass melt. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to study the split feasibility problem with multiple output sets and fixed point problem in the class of demicontractive mappings and propose relaxed inertial self-adaptive algorithms that do not use the least squares method. Under some appropriate assumptions, we establish a strong convergence result for the sequence generated by the proposed algorithm. Our result generalizes and extends several results existing in the literature. Finally, we illustrate the convergence of the proposed algorithm by using a numerical example. [ABSTRACT FROM AUTHOR]

[Display omitted] Electrowetting on conventional dielectrics requires direct fluid-electrode contact to generate strong electric fields at the three-phase contact line to modulate the wetting. Since the electric field alters wetting, the modulation of wetting can be achieved by applying an external electric field through insulated electrodes, preventing the liquid from contacting the electrodes. A simple and efficient method for non-contact between the fluid and the electrode external electric field modulation of fluid wetting was proposed. The switching ability of droplets on microgroove surfaces from Cassie-Baxter to Wenzel wetting state under an external electric field was used to drive and quantify the relationship between wetting, contact angle, and the applied voltage. Applying an external electric field modulates the wetting of deionized water, ionic liquids, and high-viscosity liquids on microgrooves. The wetting degree of liquid can be controlled by adjusting the external voltage parameters. The finite element simulations revealed that the Maxwell force drove this process. The effects of substrate size and liquid properties on wetting behavior were also examined. Post-application cross-sectional imaging showed the formation of a conformal interface, highlighting the relevance of the proposed method in advanced adaptive shape fabrication and microfluidic control, among other applications. [ABSTRACT FROM AUTHOR]

During electroslag remelting (ESR), high MgO contents are typically added to CaF 2 –CaO–Al 2 O 3 slag to control magnesium content in iron- and nickel-based alloys. The melting temperature and viscosity of ESR slag are pivotal for energy consumption, production efficiency, smooth operation, and ingot quality. However, there is currently a notable scarcity of research on the melting temperature and viscosity of CaF 2 –CaO–Al 2 O 3 –MgO slag with high MgO levels. Thus, the melting temperatures and viscosity of CaF 2 –CaO–Al 2 O 3 –MgO slags with varying MgO contents and CaO/Al 2 O 3 (C/A) ratios were investigated. The results show that as the MgO content increases from 7.83 % to 13.18 %, the final precipitation content of the MgO phase significantly increases, resulting in an increase in the melting temperature from 1306 °C to 1319 °C. With the increase in the C/A ratio from 0.86 to 1.16, the precipitation completion temperatures of the Ca 12 Al 14 F 2 O 32 and MgO phases significantly decrease and the MgAl 2 O 4 phase transforms into the CaO phase. Hence, the melting temperature decreases from 1329 °C to 1314 °C. Further increasing the C/A ratio to 1.40, the final precipitation content of the CaO phase increases, resulting in a decrease in the melting temperature from 1314 °C to 1282 °C. Moreover, as the MgO content and C/A ratio increase, the slag viscosity exhibits different change trends within various temperature ranges. This depends on which of the depolymerization of the slag structure and the precipitation and clustering of the MgO phase has a greater effect on the slag viscosity. [ABSTRACT FROM AUTHOR]

The influences of temperature and compositions (TiO 2 and CaO/SiO 2) on thermodynamics properties and structural evolutions of TiO 2 -CaO-Al 2 O 3 -MgO-SiO 2 slags were investigated in this work. The slag viscosities increased with decreasing the temperature and declined with adding TiO 2. With the raising of CaO/SiO 2 ratio, the viscosity decreased under high temperatures, while it increased with the temperature further decreased lower than 1420 °C. The enthalpy change of the slag increased with raising the temperature as well as the TiO 2 content and reduced with the CaO/SiO 2 ratio increasing. Both the liquidus temperature and break point temperature of the slags decreased with adding TiO 2 and increased with raising the CaO/SiO 2 ratio. Temperature had a significant effect on slag structure evolutions, which decreased the slag polymerization degree. With adding TiO 2 and CaO/SiO 2 ratio in slags, the slag structure stability was weakened by increasing the amount of simpler silicate and TiO 6 units and reducing the proportion of complex Ti-O units. Both the temperature and compositions (TiO 2 and CaO/SiO 2) depolymerized the slag structure to decline the viscosity. [ABSTRACT FROM AUTHOR]

The effects of B 2 O 3 on viscosities, structures and phase transitions of CaO–MgO–Al 2 O 3 –SiO 2 –MnO-(0-8.0 wt%)B 2 O 3 slags were investigated in this work. From the viscosity experimental results, the slag viscosities declined and the E η decreased from 205.19 to 175.95 kJ/mol with the addition of B 2 O 3 in slags from 0 to 8.0 wt%. From the structure analysis by using FTIR and XPS, B 2 O 3 entered into the silicate network to increase the slag polymerization degree, while the formation of simple two-dimensional BO 3 trihedral units could significantly decline the symmetry and stability of the structure. The effects of decreasing the network stability and forming low-melting eutectics were more dominated than the effects of increasing the structure polymerization degree, which could reduce the slag viscosity. Furthermore, adding B 2 O 3 could decrease the slag initial precipitation temperature and change the primary crystal phase of the slag from melilite to spinel. The comprehensive effects of reducing the slag structure stability and decreasing the influence of solid phase on viscosity eventually resulted in the improvement of the slag fluidity. [ABSTRACT FROM AUTHOR]

AbstractAn investigation on the propagation of bending waves along the edge of a piezoelectric thin plate resting on an elastic foundation (cf. Pasternak foundation) and under the action of a point-load is carried out in this paper. The displacement field of the plate is based on the classical plate theory. The Kelvin-Voigt type viscoelastic model is used to examine the viscous effect on the characteristics of the bending wave. The Moore-Gibson-Thompson (MGT) thermoelastic equation is solved for an external time variant harmonic heat source at the upper surface of the plate. The piezoelectric potential is obtained for an electrode-covered upper surface and an electrically shorted lower surface. The displacements of the propagating bending wave along the edge are examined under a time-harmonic point-load acting near the vicinity of the free edge of the plate. The well-known Green function technique and Fourier transform method are implemented to generate an analytical solution for the non-homogeneous boundary value problem. The examination of the derived explicit form of the dispersion relationship and the displacements of the bending edge wave under external loading are discussed and presented both analytically and graphically, and the results are summarized. [ABSTRACT FROM AUTHOR]

To reveal the internal flow loss characteristics of a multi-stage pump, the unsteady calculation of the internal flow field of a seven-stage centrifugal pump was carried out, and the entropy production theory and Q criterion were utilized to analyze the unsteady flow characteristics of each flow component under different flow rates. The research results show that as the flow rate increases, the entropy production value and the energy loss inside the flow components also increase accordingly. The viscous dissipation entropy production caused by fluid viscosity is very small, and the turbulent dissipation entropy production caused by turbulent fluctuations and wall dissipation entropy production are the main sources of energy loss. The impellers, diffusers, and outlet chamber are the main regions of energy loss in the multistage pump. The entropy production value of the first-stage impeller is significantly higher than that of other impellers, while the entropy production value of the first-stage diffuser is significantly lower than that of other diffusers. Through vortex structure analysis, it is found that the high entropy production regions in the impeller are concentrated in the impeller inlet area, the blade suction surface, and the impeller outlet area. [ABSTRACT FROM AUTHOR]

The energy of a focused acoustic field is quite concentrated, and the ability of an acoustic vortex formed by a concave focusing transducer array to capture objects in a flowing medium remains to be investigated. In this paper, the focused pressure distributions generated by an acoustic lens and a concave focused transducer array are firstly simulated, and the analyzed results show that the focusing effect of the latter is significantly better than that of the former. The acoustic gradient force and orbital angular momentum density distributions of the focused transducer array were investigated. A focused acoustic vortex tiny object capture system was built by simulating the hydrothermal column that forms in the seafloor hydrothermal zone. It was discovered that the forces affecting microorganisms and other small objects primarily consist of acoustic gradient force, viscous force, and additional mass force. The non-destructive capture of tiny seafloor objects was accomplished by adjusting the focused acoustic vortex's propagation direction and the transducer array's emitted power, thereby enabling more potential applications in ocean equipment. [ABSTRACT FROM AUTHOR]

This study investigates the impact of zirconium-based KZC series crosslinkers with varying zirconium contents and the polyamine-based crosslinker (PBC) on the properties of coated paper, focusing on key performance metrics such as viscosity, wet rub and pick resistance, dry pick resistance, gloss, brightness, ink set-off, and print mottle. The findings reveal that crosslinkers' type and concentration significantly influence the coating colors' viscosity, with PBC demonstrating lower low shear viscosity at lower concentrations. The KZC series showed stable viscosity across a zirconium content range of 7% to 20%, and both crosslinker types enhanced wet rub resistance at higher concentrations. Notably, the KZC series, particularly KZC7, exhibited superior wet pick resistance at increased concentrations, highlighting its effectiveness in enhancing the durability of the coating layer. All crosslinkers maintained excellent dry pick resistance, ensuring robust coating performance. While gloss and brightness were generally unaffected, KZC20, which had the highest zirconium content, slightly reduced these optical properties. Ink set-off tests indicated that the KZC series performed better at lower concentrations, whereas higher concentrations led to increased ink set-off, potentially due to over-crosslinking. Print mottle remained consistent across all crosslinkers, indicating uniform coating quality. Overall, the zirconium-based KZC series significantly enhances wet resistance and maintains high performance across various properties, though it may slightly reduce gloss and brightness and increase ink set-off at higher concentrations. PBC offers a balanced performance profile, emphasizing the need for careful crosslinker type and concentration optimization to achieve the desired coating properties for specific applications. This comprehensive evaluation provides valuable insights for developing and optimizing high-performance coated papers. [ABSTRACT FROM AUTHOR]

AbstractThe present work is implicated with the investigation of wave propagation in a homogeneous, isotropic, non-local microelongated viscothermoelastic solid half space with variable thermal conductivity under the dual phase lag (DPL) model. It is found analytically that three coupled longitudinal waves and one independent transverse wave exist in the medium which travel with distinct speeds. Reflection coefficients and energy ratios of various reflected waves are obtained analytically and presented graphically for aluminum epoxy-like material. The variations of these reflection coefficients are analyzed for different values of non-local parameter, microelongational parameter, viscosity and variable thermal conductivity. The expressions of energy ratios acquired in explicit form are also represented graphically as functions of the angle of incidence in accordance with the defined rule of conservation of energy. [ABSTRACT FROM AUTHOR]

Molecularly crowded solutions have been used to simulate cytoplasmic fluids, but little justification is provided in the literature. This work compared three key physical properties of solutions containing polyethylene glycol and sucrose against those in the cytoplasmic fluid from bacteria Escherichia coli: fluid viscosity, relaxation time (T1 and T2) of water, and the diffusion coefficient of water. It was concluded that appropriate mixtures of sucrose and polyethylene glycol 10,000, such as 10% sucrose and 15% PEG10,000 and 7.5% sucrose and 19% PEG10,000, closely mimic these properties of cytoplasmic fluid from E. coli containing around 100 mg/mL of proteins. [ABSTRACT FROM AUTHOR]

The practice of statistics has the power to motivate and support learning across the STEM (Science, Technology, Engineering, and Mathematics) disciplines. When connected with meaningful science contexts, statistical problem solving through the collection of data and subsequent data analysis, supported by contemporary graphing technology, presents opportunities to be innovative and creative in the delivery of learning across STEM curricula. Illustrated in this paper are the statistical outcomes associated with Grade 5 students, who were set the task of solving a mystery about an unknown concentration of a liquid through interpolation of data, which is seen here as finding a missing value in a dataset of two numerical variables where a relationship in the two variables can be represented in a bivariate graph. [ABSTRACT FROM AUTHOR]

The thermal stability of zeolites underlies their many applications. Structural collapse usually occurs through a series of reactions, involving an initial low‐density amorphous state (LDA), a high‐density melt (HDA), and, eventually, a dense recrystallization product. The LDA–HDA transition resembles a glass melting process; the HDA phase can sometimes be quenched into a glass. Using isothermal as well as nonisothermal in situ observation methodology on the faujasitic zeolite X and its potassium‐for‐sodium ion‐exchanged derivatives, we find a pronounced mixed‐alkali effect in the characteristic nonisothermal transition temperatures as well as in the isothermal reaction timescale of the LDA–HDA transition. The latter is taken as being directly related to the viscosity of the liquid into which the zeolite framework is melting; the apparent viscosity associated with this melting process was found to reach as high as 1015 Pa.s at 740°C. The observed mixed‐alkali effect is similar to the one observed in the dynamics of common oxide glasses and their corresponding melts. [ABSTRACT FROM AUTHOR]

DNA hydrogels, which hold potential for use in medicine, biosensors, and tissue engineering, can be produced through enzymatic rolling circle amplification (RCA) using phi29 DNA polymerase (DNAP). This paper introduces new DNAP variants designed for RCA‐based DNA hydrogel production, featuring enzymes with modified DNA binding, enhanced thermostability, reduced exonuclease activity, and protein tags for fluorescence detection or specific immobilization. We evaluated these enzymes by quantifying DNA output via quantitative PCR (qPCR) and assessing hydrogel mechanical properties through micromechanical indentation. The results showed that most variants generated similar DNA amounts and hydrogels with comparable mechanical properties. Additionally, all variants successfully incorporated non‐natural nucleotides, such as base‐modified dGTP derivatives and 2′fluoro‐dGTP, during RCA. This study's robust analytical approach offers a strong foundation for selecting new enzymes and producing DNA hydrogels with tailored material properties. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Methods Results Conclusions The aim of this study is to determine whether there are any changes in hemorheological parameters, including whole blood viscosity (WBV), plasma viscosity, erythrocyte aggregation, and erythrocyte deformability, in acute ischemic stroke patients, and to establish their relationship with stroke etiology. The study also aims to observe the changes in these parameters, if any, over time and after treatment, and to assess the correlation between risk factors for ischemic stroke and neuroimaging findings.This was a prospective observational study including 70 patients diagnosed with acute ischemic stroke within the first 3 days of the onset of symptoms and 96 healthy controls. Stroke patients were categorized based on TOAST criteria, and hemorheological parameters were measured at admission and on the fifth day post‐treatment. Erythrocyte aggregation and deformability were measured using a laser ektacytometer, and viscosity assessment was conducted with a rotational viscometer.Stroke patients exhibited significant differences from the control group in aggregation amplitude, aggregation index, and aggregation half‐time (p = 0.001, p = 0.013, p = 0.009, respectively) and showed elevated maximum value of elongation index (p = 0.000). No significant differences in WBV and plasma viscosity were observed between the groups. Post‐treatment, the small vessel occlusion subgroup demonstrated a notable reduction in WBV. Additionally, homocysteine levels showed a positive correlation with scattered white matter lesions in basal ganglia and infratentorial regions (p = 0.002, p = 0.039, respectively).Increased predisposition to erythrocyte aggregation may contribute to the occurrence of acute ischemic stroke. Moreover, gaining the ability of erythrocytes to deform and increase blood flow may serve as a compensatory mechanism in the chronic vascular disease process. The risk factors for ischemic stroke may exhibit connections to specific areas within the brain. [ABSTRACT FROM AUTHOR]

Cilial pumping is a potent mechanism used to control and manipulate fluids on microscales. Recently, we introduced an electronically driven μ-cilial platform that can create arbitrary flow patterns in liquids near a surface with the potential for various engineering applications. This μ-cilial platform, however, utilized the coupling between elasticity and viscous drag to obtain pumping and had several limitations. For example, each cilium could only pump in one direction. Thus, to create bidirectional flows, it was necessary to fabricate and separately actuate two oppositely facing cilia. As another example, the generation of non-reciprocal cilial motions, a necessary condition for pumping at these scales, could only be achieved by matching the elastic stresses inherent in actuating the cilia with the viscous drag forces generated by the flows. This criterion severely restricted the frequency range over which the cilia could be operated and resulted in a small swept area, both of which restricted the volume of fluid being pumped in each cycle. These limitations contrast with the capabilities of natural cilia, which can achieve omnidirectional transport and operation over a broad range of frequencies. In natural cilia, these capabilities arise from their complex internal structure. Inspired by this strategy we designed hinged cilia and show they can achieve bidirectional pumping of larger fluid volumes over a broad range of frequencies. Finally, we demonstrate that even regular arrays of individually controlled hinged cilia can generate a variety of flow patterns using fewer cilia than in previous cilia metasurface designs. [ABSTRACT FROM AUTHOR]

Viscosity and hypoxia, as microenvironment parameters, play important roles in maintaining normal biological processes and homeostasis. Therefore, simultaneous and sensitive detection of these elements with simple and effective methods could offer precise information in biology. Here, we report a two-site lysosome-targeting fluorescent probe, NVP, for monitoring viscosity and nitroreductase with dual emission channels (emission shift is 86 nm). The NVP probe has displayed highly sensitive and selective responses towards viscosity and nitroreductase, respectively. Significantly, the fluctuations of viscosity and NTR have been detected in vitro and in vivo. We expect that the dual-responsive fluorescent NVP probe will become a potential molecular tool for the exploration of deeper functions of viscosity and hypoxia. [ABSTRACT FROM AUTHOR]

AbstractTiO2 nanoparticles were synthesized using the reduction precipitation method, verified by powder x-ray diffraction (PXRD) with an average crystallite size of 62 nm and an average particle size of 135 nm from SEM images. Rheological studies of brake fluid with nanoparticle additives revealed that while the fluid generally maintains consistent behavior, a 2 wt.% concentration showed non-Newtonian behavior at 120 °C. Viscosity increased slightly with nanoparticle addition and decreased with rising temperature, with the 0.5 wt.% sample demonstrating the most notable increase of 18.18% at 120 °C. At 30 °C, the 1 wt.% sample exhibited a 4.06% increase. The observed viscosity changes are attributed to higher internal shear stress and the need to manage dispersion solid elements. The Herschel-Bulkley model was effective in predicting sample behavior, and all samples conformed to Reynolds’ equation μ0=be−aT. This research indicates that TiO2 nanoparticles can be effectively used as brake fluid additives, offering potential benefits for high-temperature applications in vehicles. Further optimization using mathematical models such as response surface methodology (RSM) is suggested for improved performance. [ABSTRACT FROM AUTHOR]

Background: There have been few investigations into the impact of high-intensity interval training on blood rheology. Objectives: This study aimed to evaluate how high-intensity interval training conducted with different duration affects fibrinogen and plasma viscosity in sedentary young college men. Methods: For this study, 36 healthy male participants were selected and grouped based on their individual characteristics. The groups included a control group (n = 9), a 45-second training group (tr-45; n = 9), a 30-second training group (tr-30; n = 9), and a 15-second training group (tr-15; n = 9). The training regimen comprised six sessions over two weeks, with varying sets (4, 5, 6, 6, 7, 4 respectively) and durations of 15, 30, and 45 seconds for different groups. There was a fixed 4-minute rest interval between each set, with a consistent load of 0.6 on the Wingate cycle ergometer. Blood samples were collected 48 hours before and after the final session to analyze fibrinogen and plasma viscosity levels. Results: There were no significant differences between groups in plasma fibrinogen levels (F3, 32 = 2.303, P = 0.96). However, post-test analysis revealed a significant decrease in plasma fibrinogen in the tr-45 group (P = 0.027) compared to pre-test levels. Plasma viscosity did not significantly change between groups (F3, 32 = 0.651, P = 0.058), but there was a significant interaction between time and group (F3, 40 = 4.43, P = 0.009). Post-test analysis showed a significant decrease in plasma viscosity in the tr-45 (P = 0.010), tr-30 (P = 0.002), and tr-15 (P = 0.003) groups, while it significantly increased in the control group (P = 0.004) compared to pre-test levels. Conclusions: The findings suggest that high-intensity interval training can effectively decrease blood rheology and factors such as fibrinogen and plasma viscosity, with the 45-second HIIT being more efficient. Therefore, incorporating this training into Physical Activity Programs could be beneficial for inactive men. [ABSTRACT FROM AUTHOR]

Heavy oil is an important resource in current petroleum exploitation, and the chemical composition information of heavy oil is crucial for revealing its viscosity-inducing mechanism and solving practical exploitation issues. In this study, the techniques of high-temperature gas chromatography and highresolution mass spectrometry equipped with an electrospray ionization source were applied to reveal the chemical composition of typical heavy oils from western, central, and eastern China. The results indicate that these heavy oils display significant variations in their bulk properties, with initial boiling points all above 200 °C. Utilizing pre-treatment and ESI high-resolution mass spectrometry, an analysis of the molecular composition of saturated hydrocarbons, aromatic hydrocarbons, acidic oxygen compounds, sulfur compounds, basic nitrogen compounds, and neutral nitrogen compounds within the heavy oil was conducted. Ultimately, a semi-quantitative analysis of the molecular composition of the heavy oil was achieved by integrating the elemental content. The semi-quantitative analysis results of Shengli-J8 heavy oil and a conventional Shengli crude oil show that Shengli-J8 heavy oil lacks alkanes and low molecular weight aromatic hydrocarbons, which contributes to its high viscosity. Additionally, characteristic molecular sets for different heavy oils were identified based on the semi-quantitative analysis of molecular composition. The semi-quantitative analysis of molecular composition in heavy oils may provide valuable reference data for establishing theoretical models on the viscosity-inducing mechanism in heavy oils and designing viscosity-reducing agents for heavy oil exploitation. [ABSTRACT FROM AUTHOR]

Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typically governed by gravity, viscous and capillary forces, these factors lead invasive fluids to occupy pore space irregularly and incompletely. Previous studies have demonstrated capillary numbers, describing the viscous and capillary forces, to quantificationally induce evolution of invasion patterns. While the evolution mechanisms of invasive patterns have not been deeply elucidated under the constant capillary number and three variable parameters including velocity, viscosity, and interfacial tension. Our research employs two horizontal visualization systems and a two-phase laminar flow simulation to investigate the tendency of invasive pattern transition by various parameters at the pore scale. We showed that increasing invasive viscosity or reducing interfacial tension in a homogeneous pore space significantly enhanced sweep efficiency, under constant capillary number. Additionally, in the fingering crossover pattern, the region near the inlet was prone to capillary fingering with multi-directional invasion, while the viscous fingering with unidirectional invasion was more susceptible occurred in the region near the outlet. Furthermore, increasing invasive viscosity or decreasing invasive velocity and interfacial tension promoted the extension of viscous fingering from the outlet to the inlet, presenting that the subsequent invasive fluid flows toward the outlet. In the case of invasive trunk along a unidirectional path, the invasive flow increased exponentially closer to the outlet, resulting in a significant decrease in the width of the invasive interface. Our work holds promising applications for optimizing invasive patterns in heterogeneous porous media. [ABSTRACT FROM AUTHOR]

The development of lithium-ion batteries (LIBs) has progressed from liquid to gel and further to solid-state electrolytes. Various parameters, such as ion conductivity, viscosity, dielectric constant, and ion transfer number, are desirable regardless of the battery type. The ionic conductivity of the electrolyte should be above 10−3 S cm−1. Organic solvents combined with lithium salts form pathways for Li-ions transport during battery charging and discharging. Different structures, proportions, and forms of electrolytes become crucial under conditions conducive to Li-ions transport. The critical aspects of electrolytes during operation include their impact on capacity due to cycling efficiency, thermal stability, and the growth of lithium dendrites after multiple charge–discharge cycles. Research from the past to the present has primarily evolved around exploring these electrochemical parameters. Functional electrolytes address the drawbacks by incorporating different additives to mitigate issues arising from extreme environmental temperatures, lifespan, and thermal runaway of LIBs during operation. The concentration of additives used to improve cycle life typically does not exceed 5%. Apart from discussing general electrochemical properties, safety-related impacts, such as internal material effects from chemical reactions during charging and discharging, heat tolerance, and gas generation during thermal runaway, are primary focal points in this field. In addition, the review emphasizes recent advancements in quasi-solid and solid-state electrolytes that show promise for future applications due to their enhanced thermal stability and safety profiles. Furthermore, integrating deep eutectic solvents (DES) and ionic liquids (ILs) into electrolytes is explored for their potential to improve ionic conductivity and thermal stability, presenting a comprehensive overview of the evolving landscape in LIB electrolyte research. [ABSTRACT FROM AUTHOR]

This paper investigates the continuous dependence of solutions to layered composite materials in binary mixtures on perturbation parameters defined in a semi-infinite cylinder. Due to the fact that the base of the cylinder is easily disturbed by compression, this causes disturbances to the data at the entrance. By introducing auxiliary functions related to the solution of the equations, this article analyzes the impact of these disturbances on the solutions of the binary heat conduction equations and obtains the continuous dependence of the solutions on the base. [ABSTRACT FROM AUTHOR]

This paper considered divergence-free basis methods to solve the viscous Stokes equations. A discrete divergence-free subspace was constructed to reduce the saddle point problem of the Stokes problem to a smaller-sized symmetric and positive definite system solely depending on the velocity components. Then, the system could decouple the unknowns in velocity and pressure and solve them independently. However, such a scheme may not ensure an accurate numerical solution to the velocity. In order to obtain satisfactory accuracy, we used a velocity reconstruction technique to enhance the divergence-free scheme to achieve the desired pressure and viscosity robustness. Numerical results were presented to demonstrate the robustness and accuracy of this discrete divergence-free method. [ABSTRACT FROM AUTHOR]

This study provides new experimental data for the density and viscosity of mixtures containing methyl caprate and 1-alkanol (1-propanol to 1-hexanol) at 0.1 MPa and different temperatures (293.15 K to 323.15 K). We analyzed the molecular interactions between the components and found that are weak. The PC-SAFT equation of state accurately modeled the density of the mixtures without fitted parameters. This equation of state considered hydrogen bonding between methyl caprate and 1-alkanol. Moreover, two correlations for viscosity were successfully applied to fit the experimental viscosity data with good accuracy. [ABSTRACT FROM AUTHOR]

We present a new wide-ranging correlation for the viscosity of nitrogen based on critically evaluated experimental data as well as ab-initio calculations. The correlation is designed to be used with densities from an existing equation of state, which is valid from the triple point to 1000 K, at pressures up to 2200 MPa. The estimated uncertainty (at the 95% confidence level) for the viscosity varies depending on the temperature and pressure, from a low of 0.2% in the dilute-gas range near room temperature, to 4% for the liquid phase at pressures from saturation up to 34 MPa, and maximum of 8% in the supercritical region at pressures above 650 MPa. Extensive comparisons with experimental data are provided. [ABSTRACT FROM AUTHOR]

This manuscript presents new experimental data (density and viscosity) for the binary mixtures of ethyl myristate with different secondary alcohols (2-propanol, 2-butanol, 2-pentanol, and 2-hexanol). Experimental measurements were conducted at various temperatures (293.15 K to 323.15 K), atmospheric pressure (0.1 MPa), covering a wide range of compositions for the binary mixtures. Using the experimental density and viscosity values, the molar volume excess and deviation in viscosity were obtained and the molecular interaction forces were studied as weak or strong. PC-SAFT successfully modeled the density of the mixtures without requiring any fitted parameters for the mixture. In this modeling, hydrogen bond interactions between ethyl myristate and 2-alkanol were considered. Finally, the experimental viscosity data were successfully modeled with a non-linear Belda model. [ABSTRACT FROM AUTHOR]

In this study, the microstructure, hardness, density, viscosity, and surface tension of molten pure Ti with TiC particles were studied via electrostatic levitation experiments, where the electrostatic levitation experiment involved container-less processing, which can suppress heterogeneous nucleation via crucibles. Microstructural observation revealed long needle-shaped α-grains across the whole area in the pure Ti sample. On the other hand, smaller needle-shaped α-grains were found in the samples with TiC particles. However, the detailed microstructural analysis of Ti + 0.7vo l%TiC sample revealed that the fine α-grains observed in the Ti + 0.7vo l%TiC are transformed from single grain of prior β phase. This is because the TiC particles dissolve into the molten Ti during the electrostatic levitation experiment. Instead, Ti–rich TiC precipitates formed by cooling can act as pinning sites rather than heterogeneous nucleation sites, which results in a finer microstructure for the samples with TiC particles during the electrostatic levitation experiment. The density of the samples is linearly related to the temperature, and it decreases with increasing temperature. In addition, a higher density is observed for the samples with TiC particles. Although linear relationships between the surface tension and temperature were found, the addition of TiC particles had no notable effect on the viscosity of the molten pure Ti. [ABSTRACT FROM AUTHOR]

This Note highlights the convenience of extensively flared capillary viscometers in the elimination of the kinetic energy correction and the consequent simplification of their calibration and use in liquid viscosity measurements. [ABSTRACT FROM AUTHOR]

The quality of anti-sagging performance directly influences the application scope of bimodal polyethylene. Although research exists on the characterization methods of anti-sagging performance in bimodal polyethylene, few studies have indicated which testing methods can most accurately characterize this property. This study compares different testing indicators, including melt flow index, melt strength, rheological behavior, molecular weight, and entanglement of molecular chains, to identify the most precise ones for characterizing the anti-sagging performance of polyethylene. A comprehensive analysis combining the properties of the test materials and the test results indicates that zero shear viscosity and relaxation time can effectively characterize the anti-sagging resistance properties of polyethylene. In contract, melt flow index, melt strength, and entanglement of molecular chains are inadequate for accurately characterizing anti-sagging performance. This study will provide an effective and accurate method for characterizing the modification of anti-sagging performance of polyethylene. [ABSTRACT FROM AUTHOR]

It is crucial for the successful development of fractured reservoirs to understand the interaction behavior between hydraulic fractures and natural fractures. This work employed a true-triaxial fracturing experiment using prefabricated samples with natural fractures, along with a three-dimensional (3 D) numerical model, to investigate the interaction mechanisms between hydraulic fractures and preexisting natural fractures. Various influencing factors, including the horizontal stress difference, injection rate, fluid viscosity, and approach angle, are considered. The results reveal three distinct modes of interaction between hydraulic fractures and natural fractures: crossing, deflection, and arrest. As the horizontal stress difference, injection rate, and viscosity increase, the interaction between hydraulic and natural fractures undergoes a gradual shift, evolving from arrest to deflection and ultimately crossing. A smaller approach angle enhances the likelihood of hydraulic fractures being captured by natural fractures. Furthermore, the evaluation criterion of propagating ability is proposed based on the dimensionless value to facilitate the evaluation of the interplay between hydraulic and natural fractures. The interaction behavior diagrams between hydraulic fracture and natural fracture in different regimes is established. It shows that the fracture penetration capacity gradually increases from toughness-dominated regime to viscous-dominated regime, as evidenced by the phased arrangement of arrest, deflection, and crossing in their interaction with natural fractures. When the tensile strength and cohesion of natural fractures is high, hydraulic fractures tend to pass through directly, while conversely, they are easily arrested by natural fractures. The research findings can offer valuable insights for optimizing the fracturing in unconventional reservoirs with developed natural fractures. [ABSTRACT FROM AUTHOR]

The stability range of localized three-dimensional convective cells in Rayleigh–Bénard convection is determined across a broad range of viscosity contrasts between the boundaries of the fluid layer, for both free-slip and no-slip boundary conditions. The localized convective cell is generated by a finite-amplitude initial perturbation at subcritical Rayleigh numbers. It appears as a radially symmetric upwelling surrounded by nearly stagnant fluid, which can be characterized as an extremely weak plume. The parameter range in which three-dimensional localized upwellings are stable is slightly larger than that found for two-dimensional rolls. With free-slip boundaries, the lowest viscosity contrast at which the three-dimensional system can exhibit localization is approximately 35, about four times lower than for two-dimensional rolls. The wide range of conditions under which localization occurs in three-dimensional systems due to temperature-dependent viscosity further emphasizes its importance for the understanding of processes within the interiors of planetary bodies and for industrial applications. [ABSTRACT FROM AUTHOR]

The Basset–Boussinesq force is often perfunctorily neglected when studying small inertial particles in turbulence. This force arises from the diffusion of vorticity from the particles and, since it depends on the particles' history, complicates the dynamics by transforming their equations of motion into integrodifferential equations. However, this force is of the same order as other viscous forces acting on the particles, and beyond convenience, the reasons for neglecting it are unclear. This study addresses the following question: Under what conditions can the Basset–Boussinesq force be neglected in light particles in geophysical flows? We derive strict bounds for the magnitude of the Basset–Boussinesq force in stably stratified flows, in contexts of interest for geophysical turbulence. The bounds are validated by direct numerical simulations. The Basset–Boussinesq force is negligible when a buoyancy Stokes number Sb = N τ p is small, where N is the flow Brunt–Väisälä frequency and τ p is the particle's Stokes time. Interestingly, for most oceanic particles this force may be negligible. Only for very strong stratification, or for particles with very large inertia, this force must be considered in the dynamics. [ABSTRACT FROM AUTHOR]

A theoretical analysis of the piezo-viscous dependence of micropolar fluid flow between parallel annular disks has been conducted. It is assumed that viscosity changes exponentially with pressure. Pressure is analytically approximated using a small perturbation method with the viscosity coefficient as the perturbation parameter. Squeeze film time, pressure, and load carrying capacity are calculated and graphically demonstrated across various viscosity–pressure characteristics. The study examines how an increase in cross-viscosity correlates with notable growth in pressure, response time, and bearing load. According to the results, micropolar fluid offers an increase in the load-bearing capacity and therefore lengthens the response time to prevent the contact of parallel annular disks. These observations are useful for bearings, seals, and lubrication systems, where controlling viscosity and pressure is crucial for smooth operation and productivity. As the limiting case of micro-polar fluid when the coupling number tends to zero or the couple stress parameter approaches infinity, without the annular ring, the present derivation agrees well with the Newtonian viscous case of parallel planar squeezing disks described by Bird et al. [Transport Phenomena (John Wiley & Sons, 2006)]. [ABSTRACT FROM AUTHOR]

The interplay between variations in permeability and viscosity on the onset of local thermal non-equilibrium in Darcy–Bénard convection has been investigated. Specifically, permeability is modeled as decreasing linearly with depth, while viscosity decreases exponentially. The validity of the principle of exchange of stabilities is confirmed. A linear instability analysis of the quiescent state is conducted through normal mode decomposition of disturbances, with threshold values for instability onset computed numerically using the Galerkin method. The individual and combined effects of increasing the variable permeability and viscosity parameters on the instability characteristics of the system are examined in detail, highlighting both commonalities and distinctions. It is observed that increasing each parameter individually hastens the onset of convection. However, their combined influence produces both stabilizing and destabilizing effects under certain parametric conditions. In all scenarios, an increase in the scaled interphase heat transfer coefficient consistently delays the onset of convection, whereas a higher ratio of porosity-modified conductivities has the opposite effect. Furthermore, the size of the convection cells remains unchanged at the extreme values of the scaled interphase heat transfer coefficient. [ABSTRACT FROM AUTHOR]

The compound droplet consists of the inner and outer droplets. The outer droplet's ability to isolate the inner contents from its surroundings makes applications such as drug delivery, cell encapsulation, and cell sorting possible. Here, we experimentally explore the transport of the compound droplet at different Reynolds numbers, viscosity ratios, and volume ratios. Compound droplets have a longer dimensionless transport distance along the X-axis than single-phase droplets at Reynolds numbers from 44 to 366. When the Reynolds number is increased from 81.2 to 243.7, the dimensionless maximum transport distance of the compound droplet along the X-axis becomes 2.04 times. As the Re increases, the compound droplet deflection rate decreases continuously. For a constant initial velocity of the compound droplet, an increase in the viscosity ratio leads to an increase in the dimensionless velocity along the x axis with the compound droplet during transport. The maximum transport distance along the x-axis increases, and the deflection rate decreases as the inertial and viscous forces increase with increasing viscosity and dimension ratios. The chemical droplets become more stable as a result. [ABSTRACT FROM AUTHOR]

In this study, a multivariate piecewise interpolation model is introduced to represent melt viscosity based on temperature and shear rate. The model does not require a predefined functional form for the entire data range, instead finding a suitable line between adjacent measured viscosity data points to obtain viscosity as a function of shear rate and temperature. To assess the effect of viscosity representation on polymer melt flow, a two-dimensional (2D) flow past a cylinder problem and a three-dimensional (3D) single screw extruder problem are numerically solved using different viscosity models. The pressure drop (Δ P) from the shift-factor model deviates by more than 10% at an average velocity ( U av ) of 1 m/s due to overestimation of viscosity in the high shear rate region. The dimensionless thicknesses of the thermal boundary layer near the channel wall ( δ T / H ) at wall temperature ( T w ) of 210 °C are also misevaluated by more than 4% using both the shift-factor model and the Klein model, reflecting their poor viscosity evaluation. It is noteworthy that in all viscosity models, a high T w leads to the formation of a thin thermal boundary layer, which adversely affects the heat transfer. In single screw extruder applications, viscosity misevaluation in high shear rate regions causes issues in pure drag flow cases, while misevaluation in low shear rate regions causes issues in pure back-pressure flow cases. These analyses highlight the accuracy and versatility of our multivariate piecewise interpolation model compared to existing viscosity models. [ABSTRACT FROM AUTHOR]

In this study, the dynamic behaviors of non-Newtonian fluid droplets with shear-thinning properties eccentrically impacting hydrophobic particle surfaces are investigated through a combination of numerical simulations and experiments. The simulation integrates the dynamic contact angle and a non-Newtonian fluid power-law model within the volume of fluid model framework. The effects of apparent viscosity (η), impact velocity (v0), and dimensionless eccentricity parameter (B) on the dynamic behaviors of non-Newtonian droplets are analyzed. Furthermore, the study offers insight into the progression of pressure distribution, kinetic energy, and liquid viscosity across droplets during the entire impact process. An energy balance analysis, which includes kinetic energy, surface energy, potential energy, and viscous dissipation, is employed to elucidate the fundamental physical mechanisms that govern the dynamics of eccentric impacts of non-Newtonian droplets. Finally, a model (Recr D* = −95.7 + 11 450.6e−B/0.18) is proposed to predict the adhesion or detachment of shear-thinning droplets eccentrically impacting hydrophobic particle surfaces. [ABSTRACT FROM AUTHOR]

The levitation of Leidenfrost droplets on liquid pool is fascinating, but its final stage is lack of understanding. Here, we found that a droplet levitated on liquid layer eventually deviated from Leidenfrost state once its radius was lower than a critical radius due to evaporation. The critical radius of ethanol droplet deviated from Leidenfrost state on silicone oils with a thickness ranging from 2.0 to 15.0 mm was determined by experiment. The influences of the initial radius of droplet, viscosity, and thickness of liquid layer on critical radius were analyzed. In addition, the critical radius decreases with increase in superheat for ΔT lower than 25.0 °C, whereas it does not significantly vary after ΔT exceeding 25.0 °C. The bottom temperature Tb of droplet does not approach to saturation temperature even under a high superheat. The experiment found that Marangoni convection existed inside droplet. Based on a theoretical model considering Marangoni convection, the reason for droplet deviated from Leidenfrost state was explained. These findings are helpful for understanding the final state of Leidenfrost droplet on liquid layer and would provide a potential practical application such as extinction of oil pool fires with liquids. [ABSTRACT FROM AUTHOR]

Electric fields can be used to exert controlled time-varying forces on a droplet under progressive stretching in an extensional flow, allowing for its precise manipulation in various industrial and scientific applications, including microfluidics, materials science, and biological studies. However, the interaction between the combined extensional flow field and electric field may trigger a complex electrohydrodynamic response, as determined primarily by the capillary and viscous forces and the convection of surface charge. Here, we theoretically and computationally analyze the deformation and breakup of a droplet subjected to an alternating current (AC) electric field and uniaxial extensional flow. Our asymptotic theory, applicable in the small-deformation limit, quantifies the contributions of each applied field to the shape oscillations. Numerical simulations are employed to explore the dynamical evolution of the droplet in the nonlinear regime of variation in the capillary number. Our theoretical and numerical results are in excellent agreement, demonstrating that an AC electric field can significantly alter transient deformation depending on its magnitude and frequency. We identify the threshold frequency, dependent on the ratios of electrical properties, which can induce periodic oblate-prolate shape transitions. The interaction between viscous and electric stresses driving these transients is discussed. Contrary to intuition, strong electric fields greatly suppress shape oscillations, leading instead to large continuous elongations that eventually result in an end-pinching breakup mode, forming elongated bulbous-ended droplets. The breakup state, characterized by droplet length and shape at the onset of breakup, is determined by the field parameters and the physical properties of the fluids. Notably, the breakup state length and total breakup time have a non-monotonic relationship with the applied electric field frequency. The insights gained into the physics of oscillatory stable deformation and non-oscillatory unstable deformation offer new means of droplet manipulation in droplet-based micro-mechano-electrical systems that remained unexplored thus far. [ABSTRACT FROM AUTHOR]