Shear-thinning Behavior Research Articles

The influence of non-Newtonian behaviors of blood on the hemodynamics past a bileaflet mechanical heart valve

This study employs extensive three-dimensional direct numerical simulations to investigate the hemodynamics around a bileaflet mechanical heart valve. In particular, this study focuses on assessing whether non-Newtonian rheological behaviors of blood, such as shear-thinning and yield stress behaviors, exert an influence on hemodynamics compared to the simplistic Newtonian behavior under both steady inflow and physiologically realistic pulsatile flow conditions. Under steady inflow conditions, the study reveals that blood rheology impacts velocity and pressure field variations, as well as the values of clinically important surface and time-averaged parameters like wall shear stress (WSS) and pressure recovery. Notably, this influence is most pronounced at low Reynolds numbers, gradually diminishing as the Reynolds number increases. For instance, surface-averaged WSS values obtained with the non-Newtonian shear-thinning power-law model exceed those obtained with the Newtonian model. At Re=750, this difference reaches around 67%, reducing to less than 1% at Re=5000. Correspondingly, pressure recovery downstream of the valve leaflets is lower for the shear-thinning blood than the constant viscosity one, with the difference decreasing as the Reynolds number increases. On the other hand, in pulsatile flow conditions, jets formed between the leaflets and the valve housing wall are shorter than steady inflow conditions. Additionally, surface-averaged wall shear stress and blood damage (BD) parameter values are higher (with differences more than 13% and 47%, respectively) during the peak stage of the cardiac cycle, especially for blood exhibiting non-Newtonian yield stress characteristics compared to the shear-thinning or constant viscosity characteristics. Therefore, blood non-Newtonian behaviors, including shear-thinning and yield stress behaviors, exert a considerable influence on the hemodynamics around a mechanical heart valve. All in all, the findings of this study demonstrate the importance of considering non-Newtonian blood behaviors when designing blood-contacting medical devices, such as mechanical heart valves, to enhance functionality and performance.

Anticorrosion and rheological properties of Calyptocarpus vialis extract as a green coating for mild steel in 2MH2SO4

This study assesses the rheological properties and corrosion inhibition efficacy of Calyptocarpus vialis (CV) extract, a wild plant in Asteraceae family. Shear and dynamic rheology studies show that CV extract has shear-thinning behaviour, with viscosity changes occurring at higher shear rates, most likely owing to aggregate formation. These aggregates may develop due to certain solvent characteristics and a jamming tendency is due to the presence of extract phytochemicals. Dynamic rheology confirms its viscoelastic nature. Corrosion inhibition effectiveness was investigated using Mild Steel (MS) in 2 M H2SO4, resulting in an 82.69 % inhibition with an extract concentration of 1 g/L. Adsorption isotherm indicates phytochemical adsorption on MS surface. Contact angles of polished MS (87.30°), with extract (80.10°), and without extract (51.25°) show decrease in wetting and increase in hydrophobicity which indicates that a thin protective layer is formed at MS surface. FE-SEM (Field Emission Scanning Electron Microscopy) images reveal that the CV extract forms a protective barrier on the MS surface, significantly reducing corrosion as compared to the unprotected surface exposed to the mild acid solution. Theoretical calculations, including Density Functional Theory (DFT) simulations, Monte Carlo (MC), and Molecular Dynamics (MD) simulations, support the experimental findings, elucidating phytochemicals adsorption on the MS surface. Further research is required to examine the scalability of CV extracts for industrial applications, as well as their long-term stability and efficacy in various corrosive conditions.

Investigation of Cellulose Nanocrystals Fabricated via Sulfuric Acid Combined with Deep Eutectic Solvent Route

To make full use of waste tobacco in cigarette production and enhance resource utilization efficiency, cellulose nanocrystals (CNCs) were prepared by a method of sulfuric acid combined with a deep eutectic solvent. This method was compared with conventional methods, and the CNCs were thoroughly characterized. The results indicated that the yield of CNCs prepared by the sulfuric acid combined with a deep eutectic solvent method exceeded 26%, with the highest yield reaching 29.5%, surpassing the yields from two other methods of 12.5%, 17.2%, corresponding to sulfuric acid and sulfuric acid-oxalic acid, respectively. Scanning electron microscopy revealed a laminar morphology of CNCs, in which the CNCs maintained a cellulose type I structure with well-preserved crystallinity. In addition, CNCs prepared by the sulfuric acid combined with a deep eutectic solvent method exhibited good thermal stability, with maximum mass loss at temperature of 342.8°C during third pyrolysis stage, higher than that of sulfuric acid at 316.7°C and sulfuric acid-oxalic acid at 335.9°C. Steady-state rheological testing revealed that the viscosity of the CNCs suspension decreased with an increasing shear rate, which is characteristic of pseudoplastic fluid shear thinning behavior. CNCs prepared by the sulfuric acid combined with DES method reduced the amount of sulfuric acid, and the yield was much higher than that of the other two methods. Moreover, the method using sulfuric acid combined with DES method was simple and safe, and the obtained CNCs had high thermal stability and viscosity, which expands the application prospects in biocomposite material fields.

Texture, swallowing and digestibility characteristics of a low-GI dysphagia food as affected by addition of dietary fiber and anthocyanins

Dysphagia is a common problem in the elderly population, thus texture modifications in foods suitable for dysphagic patients aroused a lot of interest. In the study, low glycemic index (GI) dysphagia foods were designed with adding dietary fiber (DF) and anthocyanins (AS), and their in vitro enzymatic digestion and predicted GI values were investigated by first-order kinetic model and slope log model. Results showed that all samples belonged to dysphagia foods at level 4 (pureed) in the International Dysphagia Diet Standardization Initiative (IDDSI) framework, and exhibited shear thinning behavior. AS reduced the apparent viscosity and storage modulus, increased redness, while DF decreased the hardness and gumminess of dysphagia food masses. DF and AS significantly increased the slowly digestible starch and resistant starch content in food system. With the increased addition of 5 % DF and 3 % AS, the predicted GI value of dysphagia food masses could be decreased to 51.08 ± 2.48, which belonged to the low-GI food, and showed the best water holding capacity and the highest total sensory evaluation score. In addition, a strong correlation was also found between the slow digestion indicators, rheological properties and swallowing ease. This study provides a theoretical foundation for the design of dysphagia food products with slow digestibility and low GI values.

Injectable Gelled Multiple Emulsion for Glucose-Responsive Insulin Delivery.

A glucose-responsive insulin delivery system that sustains blood glucose equilibrium for an extended duration can address the low therapeutic window of insulin in diabetes treatment. Herein, insulin is loaded in a water-in-oil-in-water (W1/O/W2) gelled multiple emulsion using poly (4-vinylphenylboronic acid) (PVPBA) homopolymer as an effective emulsifier. The gelled multiple emulsion exhibits a high encapsulation efficiency (99%), enhanced stability and remarkable shear-thinning behavior, making it easy to inject. Under hyperglycemic conditions, the gelled emulsion system instantly binds to glucose molecules and reduces the hydrogen bonds of the PVPBA homopolymer, resulting in insulin release. In a streptozotocin-induced type 1 diabetic mouse model, a single subcutaneous injection of the gelled emulsion rapidly responds to high blood glucose concentration (BGC)and release insulin in a glucose dependent manner, thus prolonging the antihyperglycemic effect compared with free insulin.

Effects of cooking and market classes on nutritional and antioxidant properties of dry bean flours and soluble dietary fiber-rich fractions

Dry beans are a rich source of proteins, starch, dietary fiber, and phenolic compounds, thus exhibiting potential health benefits. Fractionating dry beans, especially soluble dietary fiber (SDF), could be considered a valuable functional food ingredient. This study investigated the effects of pinto and black dry bean market classes and atmospheric pressure cooking on the physicochemical attributes of dry bean flours and the extraction and characterization of SDF-rich fractions. Cooking significantly (p < 0.05) increased the dietary fiber content, altering the macronutrient profile. Raw flours exhibited higher levels of extractable phenols and antioxidant capacity, while cooked flours had more hydrolyzable phenols and associated antioxidant activities. Pinto beans were found to have higher levels of slowly digestible starch (23.76%) and resistant starch (5.24%) compared to black beans (20.63% and 3.22%, respectively). The SDF-rich fraction from cooked flours showed a reduced residual protein content and included pectic polysaccharides, hemicelluloses, and raffinose family oligosaccharides (RFOs), with cooking affecting their molecular weight distribution. These fractions demonstrated shear-thinning behavior and temperature-dependent viscosity. The study highlights the significant influence of market class and cooking process on the nutritional and antioxidant properties of dry beans, suggesting their potential contributions to dietary health.

Effect of Balangu seed gum as an edible coating on oil absorption and quality properties of chicken fillets

Deep-fat fried foods can cause health hazards like obesity and cardiovascular diseases. Gum-based coatings can largely overcome these impediments by reducing oil absorption. This study evaluated the effect of wheat flour batters containing Balangu (Lallemantia royleana) seed gum (BSG) at various concentrations (0.5, 1, 1.5, and 2% w/v) on batter pickup, moisture and oil contents, color, and sensory properties of deep-fat fried chicken fillets. Investigating the batters' rheological characteristics demonstrated shear-thinning behavior. BSG addition improved the batters' water-holding capacity (WHC) and viscoelastic properties. Steady shear rheological data best fitted with the Herschel-Bulkely model (R2 ≥ 0.98). BSG-contained coating decreased the fillets’ moisture loss and oil uptake during deep-fat frying at 180 °C for 8 min. BSG at a 1.5% level made a 27.21% enhancement in moisture content, a 42.95% reduction in oil absorption, and an 89.65% increase in coating pickup compared with the control at the end of the frying process. No significant differences were observed for taste and odor concerning BSG presence (P > 0.05). Consequently, BSG addition to the batter formulation can be proposed for producing reduced-oil fried products with reasonable acceptability among consumers.

Dynamics of non-Newtonian fluid–fiber interactions and void formation mechanism based on fused filament fabrication

Due to the presence of internal defects such as voids in the composites manufactured by material extrusion additive manufacturing (MEX AM), the mechanical properties of the composites are significantly below the theoretical optimum. Under this circumstance, this paper is intended to investigate the effects of nozzle feeding angles and to analyze the void formation and evolution of multiphase flow, in which systematic computational fluid dynamics numerical simulations are conducted. The volume of fluid model and overset grid method are used to simulate the extrusion deposition process of carbon fiber-reinforced polymer composites, and the Carreau model is used to represent the shear-thinning behavior of molten polymer. The numerical method is validated against previously experimental and numerical simulation data. The numerical results show that the key factor leading to void formation is the vortices caused by fiber oscillation. The intense vortex at the front end of the fibers disrupts the interface between molten polymer and air, creating a beneficial condition for air to enter. Nozzle tilting can effectively reduce the probability of void formation by decreasing the fiber oscillation velocity. The results of the present study provide insights into the development and optimization of printer nozzles to enable the printing of longer fibers with less probability of potential void formation.

Thermosensitive multivesicular liposomal hydrogel: a potential platform for loco-regional drug delivery in the treatment of osteomyelitis caused by antibiotic-resistant biofilm-forming bacteria.

Biofilm-mediated osteomyelitis presents significant therapeutic challenges. Given the limitations of existing osteomyelitis treatment approaches, there is a distinct need to develop a localized drug delivery system that is biocompatible, biodegradable, and capable of controlled antibiotic release. Multivesicular liposomes (MVLs), characterized by their non-concentric vesicular structure, distinct composition, and enhanced stability, serve as the system for a robust sustained-release drug delivery platform. In this study, various hydrogel formulations composed of poloxamer 407 and other hydrogels, incorporating vancomycin hydrochloride (VAN HL)-loaded MVLs (VAN HL-MVLs), were prepared and evaluated. The optimized VAN HL-MVL sol-gel system, consisting of poloxamer 407 and hyaluronic acid, successfully maintained drug release for up to 3 weeks and exhibited shear-thinning behavior at 37°C. While complete drug release from MVLs alone took place in 312 h, the hydrogel formulation extended this release to 504 h. The released drug effectively inhibited the Staphylococcus aureus biofilms growth within 24 h and methicillin-resistant S. aureus biofilms within 72 h. It also eradicated preformed biofilms of S. aureus and methicillin-resistant S. aureus in 96 and 120 h, respectively. This injectable in situ gel system incorporating VAN HL-MVLs holds potential as an alternative to undergoing multiple surgeries for osteomyelitis treatment and warrants further studies.

From plant to nanomaterial: Green extraction of nanomucilage from Cordia dichotoma fruit and its multi-faceted biological and photocatalytic attributes

This study aimed to evaluate the extraction efficiency of mucilage from Cordia dichotoma fruits using various aqueous extraction methods, including microwave-assisted water extraction (MWE), hot-water extraction (HWE), and cold-water extraction (CWE). Different analytical techniques were employed to characterize the Cordia dichotoma mucilage (CDM). Additionally, the functional properties, anti-microbial, anti-inflammatory, and dye reduction potential of CDM were assessed. The results indicated a significantly (p < 0.05) higher yield of CDM (13.44 ± 0.94 %) using MWE compared to HWE (12.08 ± 0.82 %) and CWE (7.59 ± 0.73 %). The optimal extraction condition was utilized for the spray-drying process, yielding a spray-dried mucilage powder (SDMP) with a yield of 9.52 ± 1.27 %. The presence of galactose and arabinose as major sugar and functional groups such as OH, COOH, CH, and NH from proteins, uronic acids, and sugars were identified. CDM predominantly comprises galactose and arabinose as major sugars. CDM particles exhibited an irregular morphology and demonstrated thermal stability, with maximum weight loss occurring between 221.83 and 478.66 °C. The particle size of CDM was 681.16 ± 2.18 nm with a zeta potential of −21.46 ± 1.72 mV. Rheological analysis revealed that CDM exhibits shear-thinning behavior. Furthermore, CDM displayed inherent biological activities, including antimicrobial and anti-inflammatory properties. The dye reduction potential of CDM was evidenced by an 88.67 % degradation of indigo carmine dye. In summary, this study provides insights into the cost-effective extraction methods for CDM and its potential utilization as an eco-friendly material for dye reduction.

Optically active carbon dot/cellulose nanocrystal hydrogel printing inks with two-step authentication

The counterfeit market in field of consumer goods is still a great obstacle to financial well-being for manufacturers and consumers. Security labels with hidden images have proven to be an effective anticounterfeiting measure. Three-dimensional (3D) printing is an effective approach to fabricating labels with complex geometries using environmentally friendly and cost-effective customized inks. In this work, optically active hydrogels were made by incorporating fluorescent carbon dots (CDs) into a cellulose nanocrystal (CNC) matrix. The CD:CNC ratios were optimized to obtain inks with high viscosity and fidelity that exhibited shear-thinning behavior. The resulting inks showed good printability and the extrusion parameters were optimized to achieve high printing accuracy. When excited at different wavelengths, the printed patterns fluoresced different colors. CNC also showed shear-induced alignment upon extrusion, which is visible under polarized light, allowing hidden images to be incorporated into the printed structures for two-factor authentication.

Optimizing Tilapia-based surimi ink for 3D printing: Enhancing physicochemical properties and printability with Ulva powder

The elderly face malnutrition and dysphagia. 3D printing with high-protein surimi offers an innovative way to customize nutrition and texture of foods for the elderly. This study explored whether tilapia-based surimi ink (TBSI) with Ulva powder (UP, 0–3 %) could improve physicochemical properties and printability as an alternative to traditional pollock-based surimi ink (PBSI). TBSI showed a more uniform microstructure, greater water-holding capacity (WHC), and better printability with consistent extrusion than PBSI. Adding UP to TBSI promoted cross-linking and enhanced microstructure and WHC. Rheological analysis revealed that all inks exhibited shear-thinning behavior. UP increased complex viscosity, storage modulus, and loss modulus. Notably, UP above 2 % improved protein matrix uniformity, structural integrity, and printability, as confirmed by FT-IR and 3D printing tests. The hardness of steamed TBSI fish cake increased when infill density increased. This study highlights the potential of TBSI with UP for 3D printing to prepare personalized and elderly-friendly food.

Biobased hydrogel bioinks of pectin, nanocellulose and lysozyme nanofibrils for the bioprinting of A375 melanoma cell-laden 3D in vitro platforms

Melanoma is one of the most aggressive types of skin cancer, and the need for advanced platforms to study this disease and to develop new treatments is rising. 3D bioprinted tumor models are emerging as advanced tools to tackle these needs, with the design of adequate bioinks being a fundamental step to address this challenging process. Thus, this work explores the synergy between two biobased nanofibers, nanofibrillated cellulose (NFC) and lysozyme nanofibrils (LNFs), to create pectin nanocomposite hydrogel bioinks for the 3D bioprinting of A375 melanoma cell-laden living constructs. The incorporation of LNFs (5, 10 or 15 wt%) on a Pectin-NFC suspension originates inks with enhanced rheological properties (shear viscosity and yield point) and proper shear-thinning behavior. The crosslinked hydrogels mimic the stiffness of melanoma, being stable under physiological and cell-culture conditions, and non-cytotoxic towards A375 melanoma cells. P-NFC-LNFs (10 %) reveals good printability (Pr = 0.89) and printing accuracy (51 ± 2 %), and when loaded with A375 cells (3 × 106 cells mL−1) the bioink originates 3D-constructs with high cell viability (92 ± 1 %) after 14 days. The potential of the constructs as in vitro models is corroborated by a drug-screening test with doxorubicin, where cells within the model displayed high sensitivity to the drug.

Fabrication and characterization of novel curcumin-loaded thermoreversible high amylose maize starch emulsion gel

This study developed a novel thermoreversible emulsion gel system based on high amylose maize starch (HAMS) and investigated the impact of the oil-to-water ratio on its physicochemical properties and encapsulation performance (using curcumin as model guest molecule). Electron microscopy showed a tightly porous network structure of the HAMS-based emulsion gels. Thermal results revealed a sol-gel transition occurring in the range of 59.41 to 67.64 °C for the prepared emulsion gels. Rheological analysis suggested that all samples displayed shear-thinning behavior and HAMS-based emulsion gels exhibited typical gel-like behavior with the gel strength bolstered by higher aqueous phases. Particle size analysis showed that droplet size of emulsion gel decreased from 245 to 184 nm with increased starch aqueous phase content. Texture profile analysis indicated enhanced strength, hardness, and chewiness of the emulsion gel with increased aqueous phases. Curcumin encapsulation efficiency in the HAMS-based emulsion gel also improved with higher aqueous phase content, reaching up to 93.82 %, which attributed to the smaller droplets caused increased interfacial area. The novel HAMS-based emulsion gel system showed considerable encapsulation capacity and desirable mechanical properties. It provided valuable insights into the application of starch-based emulsion gels in food and medical area.

Oleogels loaded with lycopene structured using Zein/EGCG/Ca2+ complexes: Preparation, characterization and potential application

Oleogels have attracted considerable attention due to their excellent viscoelasticity and high content of polyunsaturated fatty acid. This study explored the potential of Zein/(−)-epigallocatechin-3-gallate/Ca2+ complexes oleogels loaded with lycopene as potential substitute for solid fats in biscuit formulations. Utilizing an emulsion-templated method, oleogels were prepared and characterized for visual appearance, droplet size, microstructure, and rheological properties. The incorporation of lycopene indicated a dose-dependent effect on these characteristics, achieving optimal properties at a concentration of 0.3 mg/mL. At this concentration, oleogels exhibited higher encapsulation efficiency (> 90 %), lower oil loss (< 2 %), and denser network structures. Rheological analysis highlighted the shear-thinning behavior, gel-like structure, and thixotropic recovery of oleogels. Substituting of margarine with lycopene-loaded oleogels in biscuits yielded products with regular appearance, uniform color, and potential health benefits, demonstrating the viability of these oleogels as a healthier alternative to traditional solid fats in baking.

Synthesis and characterization of chitosan-pectin fabricated nanoemulsion for ethylhexyl triazone topical delivery

This study aimed to investigate the stability of nanoemulsions for the UVB filter, ethylhexyl triazone (EHT) encapsulation followed by fabrication with chitosan and pectin. Four formulations were developed to assess the influence of hydrophile-lipophile balance (HLB) values on nanoemulsion stability for EHT encapsulation, targeting high Sun Protection Factor (SPF) values. The selected nanoemulsion was then subjected to fabrication with chitosan and pectin, followed by physical characterization and rheological behaviour study. Results indicated that all nanoemulsions exhibited particle sizes ranging from 137.7 nm to 206.0 nm and high entrapment efficiency from 88.76 % to 91.98 %. Sample N3, containing 1 % Tween 20 and 2 % polyethylene glycol (PEG) 400 with HLB of 12, demonstrated the highest stability, yielding a significantly elevated SPF value (10.33). Moreover, polymer-coated nanoemulsions with a low concentration of chitosan (0.1 %) showed enhanced stability when combined with different percentages of pectin. Polymer-coated nanoemulsions indicated shear-thinning behaviour at lower shear rates to Newtonian flow at higher shear rate. Furthermore, both polymer-coated and uncoated nanoemulsions exhibited decreased viscosity with increasing temperature. Also, polymer-coated nanoemulsions was found to enhance the sustainable release of EHT. These findings demonstrated the potential of polymer-coated nanoemulsions for skin application, offering enhanced stability and improved flow behaviour. The design of polymer-coated nanoemulsions could potentially minimize the risks of accumulation and toxicity of UV filters by providing a sustainable release behaviour.

Fabrication and characterization of Zanthoxylum schinifolium essential oil Pickering emulsion stabilized by bacterial cellulose nanofibrils/whey protein isolate complexes and fortified with cinnamaldehyde

The inherent hydrophobicity, high volatility, instability and pungent flavor of Zanthoxylum schinifolium essential oil (ZSEO) are important issues to restrict its preservation and practical applications. To overcome these drawbacks, the ZSEO-loaded Pickering emulsions stabilized by bacterial cellulose nanofibrils/whey protein isolate (BCNFs/WPI) complexes and fortified with cinnamaldehyde (CA) were fabricated, and their physical property and functionality were characterized. When the concentration of BCNFs/WPI complexes was 0.7 wt%, the emulsions had the smallest and uniform droplet size (<150 nm) and showed good stability over 30 d storage. Moreover, the emulsions with different CA contents (0–1.0 wt%) maintained a long-term stability with no significant droplet size change during 30 d storage. All Pickering emulsions showed a shear-thinning behavior, and their apparent viscosity and viscoelastic moduli gradually increased with the increase of BCNFs/WPI complexes contents. The presence of CA enhanced the physical stability of emulsions against environmental stresses such as acid, heat and salinity. Compared to free ZSEO, the ZSEO-loaded Pickering emulsions fortified with CA not only improved the stability of ZSEO, but also maintained or even enhanced its antioxidant and antimicrobial activity. This study would provide a promising strategy for ZSEO encapsulation and improve its stability and functionality in food applications.

Optimizing solar collector through constructal design of Y-shaped networks with power-law nanofluid flow

Solar energy is a plentiful and renewable resource; therefore, its use through clean energy technologies is necessary to reduce the consumption of fossil fuels and their consequent impact on the environment. Solar thermal energy can be harnessed to collect thermal energy through solar collectors for domestic or industrial use. In this work, a Y-shaped duct network was developed for a solar collector with a disc-shaped body. The shape and size of the network were defined using the constructal design method to harvest greater thermal energy from exposure to irradiance. For this purpose, the working fluid was a nanofluid composed of nanoparticles and a base fluid with non-Newtonian behavior, as described by the power-law model. The properties of the nanofluid were described using theoretical models that depend on the volume fraction of the nanoparticles in the base fluid. The aspect ratio of each element in the network was defined under the condition of minimum thermal resistance. For the shear-thinning nanofluid with a volume fraction of 0.04, the thermal resistance was reduced by 5.5% with an aspect ratio 5.8% lower than that of the pure base fluid. The minimum thermal resistance of the Y-shaped network arrangement occurs for shear-thinning fluids, whereas thermal resistance increases for shear-thickening fluids. This effect can be observed at different levels of branching and in pumping power. Results show that increasing the volume fraction of the nanofluid and base fluid with shear-thinning behavior aids in achieving minimal thermal resistance more easily with a smaller network. The above offers new design options for devices optimized to improve solar harvesting and thermal management, through shape, structure and rheological characteristics.

Forced Wetting of Shear-Thinning Fluids in Confined Capillaries.

Dynamic wetting in confined spaces is pivotal for the functional efficiency of biological organisms and offers significant potential for optimizing microdevices. The fluids encountered in such scenarios often exhibit shear-thinning behavior, which gives rise to complex interfacial phenomena. Here, we present an intriguing wetting phenomenon for shear-thinning fluids in confined capillary spaces. The employed shear-thinning fluids, carboxymethyl cellulose aqueous solutions with mass fractions of 0.5, 1.0, and 1.5 wt %, exhibit an intermediate state between ideal viscoelastic liquids, viscoelastic solids, and gel-like properties. We elucidate the geometric effect on its capillary wetting behavior, demonstrating that distortion of the moving contact line alters flow dynamics near the front corner, modifying the viscous resistance. This intricate interplay between the modified viscous resistance and the driving force results in a novel dynamic equilibrium distinct from that in Newtonian fluids. We further reveal that the viscous resistance in confined capillaries is controlled by both the morphology of the moving contact line and the shear-thinning exponent, particularly within the range of 0.7 to 1. This novel mechanism provides a pathway for manipulating the wetting dynamics of complex fluids in confined spaces.

Numerical-experimental estimation of the deformability of human red blood cells from rheometrical data

The deformability of human red blood cells (RBCs), which comprise almost 99% of the cells in whole blood, is largely related not only to pathophysiological blood flow but also to the levels of intracellular compounds. Therefore, statistical estimates of the deformability of individual RBCs are of paramount importance in the clinical diagnosis of blood diseases. Although the microscale hydrodynamic interactions of individual RBCs lead to non-Newtonian blood rheology, there is no established method to estimate individual RBC deformability from the rheological data of RBC suspensions, and the possibility of this estimation has not been proven. To address this issue, we conducted an integrated analysis of a model of the rheology of RBC suspensions, coupled with macrorheological data of human RBCs suspended in plasma. Assuming a nonlinear curve of the relative viscosity of the suspensions as a function of the cell volume fraction, the statistical average of the membrane shear elasticity was estimated for individual intact RBCs or hardened RBCs. Both estimated values reproduced well the experimentally observed shear-thinning non-Newtonian behavior in these suspensions. We hereby conclude that our complementary approach makes it possible to estimate the statistical average of individual RBC deformability from macrorheological data obtained with usual rheometric tests.