Viscosity Behavior Research Articles

Shear viscosity of electrorheological complex plasmas

Abstract In this paper, we investigate the behavior of shear viscosity for three-dimensional electrorheological complex plasmas (CPs) liquids by using the computational method (molecular dynamics simulations) under an external AC electric field (M T ). The Green–Kubo formula is used to calculate the shear stress autocorrelation function (A η (t)) and their integrals (coefficients, η) under the influence of M T , across numerous values of CPs parameters. By comparing the presented simulation results obtained under the absence of M T (=0.0) and at equilibrium strength (M T = 0.007), we analyze and discuss their implications in relation to existing theoretical, simulation, and experimental findings. Our observations demonstrate that the M T significantly influences the shear viscosity (dynamics) of CPs. Simulation results demonstrated that decay, magnitude, and time of A η (t) gradually decreased with increasing the M T , and coefficients η increased in the order of magnitude as expected. These results identified three distinct regimes: a slight decrease in η at low M T intensities, high increase at intermediate, and a relatively constant behavior at higher M T intensities. We demonstrate that employing the Green–Kubo relation for effective interparticle potential in CPs yields safe, reliable, and accurate estimations of M T effects on shear viscosity. Our findings of η demonstrate the electrorheological characteristics of CPs, offering insights into phase transitions using electric fields.

Thermoresponsive Gels with Rosemary Essential Oil: A Novel Topical Carrier for Antimicrobial Therapy and Drug Delivery Applications

This study investigates the development and comprehensive characterization of innovative thermoresponsive gels incorporating rosemary essential oil (RoEO) encapsulated in poly(lactic-co-glycolic acid) (PLGA) microparticles, with a focus on their potential applications in topical antimicrobial and wound healing therapies. RoEO, renowned for its robust antimicrobial, antioxidant, and wound-healing properties, was subjected to detailed chemical profiling using gas chromatography-mass spectrometry (GC–MS), which identified oxygenated monoterpenes as its dominant constituents. PLGA microparticles were synthesized through an optimized oil-in-water emulsion technique, ensuring high encapsulation efficiency and structural integrity. These microparticles were thoroughly characterized using Fourier-transform infrared (FTIR) spectroscopy to confirm functional group interactions, scanning electron microscopy (SEM) for surface morphology, X-ray diffraction (XRD) for crystalline properties, and thermal analysis for stability assessment. The synthesized microparticles displayed uniform size distribution and efficient encapsulation, demonstrating compatibility with the gel matrix. Two distinct thermoresponsive gel formulations were developed using varying ratios of Poloxamer 407 and Poloxamer 188 to achieve optimal performance. The gels were evaluated for key physicochemical properties, including pH, gelation temperature, viscosity, and rheological behavior. Both formulations exhibited thermoresponsive gelation at skin-compatible temperatures (27.6 °C and 32.9 °C), favorable pH levels (6.63 and 6.40), and shear-thinning behavior suitable for topical application. Antimicrobial efficacy was assessed against common pathogens associated with skin infections, including Staphylococcus aureus, Escherichia coli, and Candida albicans. The RoEO-PLGA-loaded gels demonstrated significant inhibitory effects, confirming their potential as effective carriers for controlled and localized drug delivery. These findings underscore the promising application of RoEO-PLGA-loaded thermoresponsive gels in addressing challenges associated with topical antimicrobial therapies and wound care, offering an innovative approach to enhancing therapeutic outcomes. By integrating the bioactive potential of RoEO with the advanced delivery capabilities of PLGA microparticles and thermoresponsive gels, this study paves the way for the development of next-generation formulations tailored to meet the specific needs of localized drug delivery in skin health management.

Development of an Operational Map for the 3D Printing of Phytosterol-Enriched Oleogels: Rheological Insights and Applications in Nutraceutical Design

Three-dimensional (3D) printing attracts significant interest in the food industry for its ability to create complex structures and customize nutritional content. Printing materials, or inks, are specially formulated for food or nutraceuticals. These inks must exhibit proper rheological properties to flow smoothly during printing and form stable final structures. This study evaluates the relationship between rheological properties and printability in phytosterol-enriched monoglyceride (MG) oleogel-based inks, intended for nutraceutical applications. Key rheological factors, including gelation temperature (Tg), elastic (G′) and viscous (G″) modulus, and viscosity (µ) behavior with shear rate (γ˙), were analyzed for their impact on flow behavior and post-extrusion stability. Furthermore, this study allowed the development of an operation map to predict successful printing based on material µ and Tg. Oleogels (OGs) were prepared with high-oleic sunflower oil (HOSO) and 10 wt% MG, enriched with phytosterols (PSs) at concentrations between 0 and 40 wt%. While higher PS content generally led to an increase in both Tg and µ, the 10 wt% PS mixture exhibited a different behavior, showing lower Tg and µ compared to the 0 wt% and 5 wt% PS mixtures. The optimal PS concentration was identified as 20 wt%, which exhibited optimal properties for 3D printing, with a Tg of 78.37 °C and µ values ranging from 0.013 to 0.032 Pa.s that yielded excellent flowability and adequate G′ (3.07 × 106 Pa) at room temperature for self-supporting capability. These characteristics, visualized on the operational map, suggest that 20% PS OGs meet ideal criteria for successful extrusion and layered deposition in 3D printing.

Exploring novel aspects of designed macromolecular structures on their interactions with cement and nano/microsilica particles and rheological properties

Various copolymers and novel branched terpolymers with different sulfonate ion and amine groups were prepared and characterized. Zeta potentials of cement slurries increased following the addition of synthesized polymers, indicating the effects of molecular weight, sulfonate ion and polyethylene glycol (PEG) branch. The rheology experiments revealed that it is possible to control the viscosity of cement slurries by varying the molecular structures of the resulting polymers. The formation of different networks through interactions between nano/microsilica and various polymer chains was accounted for the diversity in viscosity. The viscosity behavior of polymer-modified cement slurries was fit by the Generallized Newtonian Power-Law model. The results of SEM showed that polymer structures have an effect on the microstructure and morphology of cement, such as the dispersion, shape and size of hydrated calcium silicate (CSH) gels, as well as the dispersion of nano/microsilica particles. The presence of nano/microsilica particles along with various copolymers increased the hardness of the 1 and 7-day hydration cement. These results provide new ideas to control cement slurries properties using novel functional and branched polymers and nano/micro silica.

ANALYSIS OF RHEOLOGICAL PROPERTIES IN PE FIBER-REINFORCED FLY ASH GEOPOLYMER FOR ADDITIVE MANUFACTURING

The leading edge of construction advancements is represented by 3D printing which creates durable and elaborate structures and minimizes resource wastage. As a viable substitute for regular cement materials highlights the ecological benefits and strong mechanical traits of fly ash geopolymers. This study investigates how the addition of polyethylene (PE) fibers alters these properties and how varying concentrations influence the flow behavior and capability of producing the composite material. The analysis of non-Newtonian behavior in these fiber-reinforced geopolymers is conducted using the Herschel-Bulkley model. By precisely measuring critical rheological factors such as viscosity and flow behavior researchers can evaluate how they influence 3D printing processes. This research reveals that adding PE fibers boosts the material’s strength and improves resistance against cracking while also elevating the viscosity and yield stress that can hinder its passage through the printer’s nozzle. An optimal blend of fiber content emerges from controlled tests that align increased durability with controllable extrusion flow and structure reliability. The results offer deep practical applications that reveal methods for producing geopolymers that can maintain strength while meeting the exacting requirements of 3D printing methods. Research deepens the grasp of how adding fibers alters the properties of geopolymers and enriches the overall dialogue on green building materials. It opens doors for subsequent analysis of complex fiber systems and creative additive practices to boost the effectiveness and resilience of construction materials in practical use.

DEVELOPMENT AND EVALUATION OF TOPICAL HERBAL GELS WITH PLANT EXTRACTS FROM LIMONIUM GMELINII

The article presents the results of the development of topical gel formulations based on plant extracts derived from the roots and the above-ground parts of Limonium gmelinii, in accordance with the ICH Q8 (R2) “Pharmaceutical development” guideline. The study evaluated the compatibility of plant extracts with excipients and optimized their content in the gel formulations. Carbomer was used as the gelling agent, while propylene glycol (PG), glycerin, and PEG-400 were applied as co-solvents and penetration enhancers. Various concentrations of carbomer and PG were tested to determine the most optimal gel compositions. The optimal formulations were selected based on organoleptic characteristics, colloidal and thermal stability, rheological properties, and the release kinetics of plant extracts. Gels containing 1.0% carbomer demonstrated optimal viscosity and thixotropic behavior, ensuring ease of application and product stability. The use of 10.0% PG resulted in a cumulative release of 87.36% for the above-ground parts extracts and 85.78% for the root extracts in in vitro tests. Long-term stability of the gels was confirmed over 12 months of storage. These results suggest that the developed gels have significant potential for further pharmaceutical development and may have therapeutic applications in treating various diseases.

Flow modeling in a metering section of a single screw extruder with a small helix angle based on the energy dissipation rate

AbstractIn the present work, an approach based on energy dissipation rate was presented for quantifying the screw characteristics, effective Reynolds number, viscosity, and shear rate of non‐Newtonian fluids in the metering zone of a single screw extruder, characterized by a small helix angle. The flow is separated into two individual flows: one induced by the screw rotation, known as rotational flow, and another driven by back‐pressure from the die, known as pressure‐driven flow. We start by investigating the individual flow problems separately, specifically focusing on the torque and rotation speed correlations in the rotational flow and exploring pressure buildup and flow rate correlations in the pressure‐driven flow. Following this, a method to quantify the combined flow, which includes both rotational and pressure‐driven flows, is formulated by blending the relationships from each of the individual flow, employing mixture rules to determine shear rate. The mixture rules involve a key parameter, the velocity ratio, to define the flow rate contribution of the two individual flows to the combined flow. The proposed method for quantifying flow is confirmed, by comparing the results with numerical simulations employing three different inelastic non‐Newtonian fluids. The proposed method can be employed to predict the pressure buildup and the torque and to monitor the viscosity behavior of the material as a function of the shear rate. A comparison of the theoretical predictions and the numerical simulation results for the estimation of pressure buildup, torque, and shear‐rate dependent viscosity revealed discrepancies of 11.7%, 3.6%, and 6.2%, respectively. Furthermore, we report that the commonly used relationship between dimensionless pressure number and dimensionless throughput number for a Newtonian fluid is applicable to that of non‐Newtonian fluids, with the effective viscosity employed in the present study.Highlights Accurate estimation of representative viscosity of non‐Newtonian fluids for the flow in a single screw. The flow in the screw is split into a rotating flow and a pressure‐driven flow. Representative shear rates can be determined by rotational speed and flow rate.

Rheological, microbiological, and in vitro digestive properties of Kefir produced with different Kefir grains and commercial starter cultures.

This research investigates the production of kefir using Turkish and Kazakh kefir grains and commercial starter cultures, followed by storage at 4 °C for 30 days. The study monitors the rheological properties and microbiological characteristics of kefir on the 1st, 15th, and 30th days of storage, as well as during dynamic in vitro gastrointestinal digestion. Kefir samples were passed through a dynamic in vitro gastrointestinal model simulating the digestive processes of the mouth, stomach, and small intestine which was designed in laboratory conditions. Kefir from Turkish kefir grain exhibited the lowest average titratable acidity, apparent viscosity, and flow behavior index, while kefir from Kazakh kefir grain had the highest average pH. Over the storage period, pH and flow behavior index decreased, while titratable acidity, viscosity, and consistency coefficient increased. The kefir samples showed non-Newtonian pseudoplastic flow characteristics. The acetic acid bacteria and Leuconostoc counts of kefir samples produced with commercial starter cultures were higher than those produced with kefir grains, while yeast counts were higher in kefir samples produced with kefir grains. During storage and in vitro gastrointestinal digestion, the number of microorganisms in kefir samples decreased. Turkish kefir grain resulted in the lowest reduction (%) of microorganism counts during in vitro gastrointestinal digestion. These findings shed light on the rheological, microbiological, and in vitro digestive properties of kefir during storage, which may contribute to improving the quality and health benefits of kefir products. The present study revealed that the kefir produced with kefir grains had a lower decrease in the viability of microorganisms compared to the kefir produced with starter culture after passage through the gastrointestinal model, so kefir produced with kefir grains may be more preferred due to its possible health benefits.

Pipeline Transport Performance of Paste Backfill Slurry in Long-Distance Underground Backfilling: A Review

This paper reviews recent advancements in the pipeline transport performance of paste backfill slurry in long-distance underground backfilling operations, with a primary focus on applications in metal mines. Key aspects, including flow performance, energy consumption during transport, and operational stability, are discussed in detail. Slurry concentration and rheological properties, including viscosity, yield stress, and flow behavior, as well as particle size distribution, are examined for their effects on transport efficiency. The relationship between these characteristics and pipeline resistance is also examined. Factors like pipeline orientation, configuration, diameter, length, elbow design, and elevation gradients are explored, demonstrating that careful design can optimize flow performance, reduce energy consumption, and minimize the risk of blockages and bursts. Additionally, the roles of commonly used additives, such as water reducers, foaming agents, antifreeze agents, and thickeners, are discussed in terms of their impact on slurry flowability, stability, and resistance losses. Optimal slurry regulation, strategic pipeline design, and effective additive utilization improve flow efficiency, extend service life, and reduce maintenance costs, thereby ensuring reliable backfill operations. Future research should focus on innovative pipeline designs, such as improving material selection and configuration to optimize flow stability and reduce energy consumption. Advanced additives, including thickeners and water reducers, could further enhance slurry flowability, reduce pipeline resistance, and improve system reliability.

Design and Analysis of Fluorine-Free Mold Fluxes for Continuous Casting of Peritectic Steels.

Fluorine-based mold fluxes are critical for continuous casting of peritectic steels, controlling heat transfer and preventing cracks. However, environmental and health concerns associated with fluorine have spurred the search for alternative flux compositions. This study applied a factorial design to explore the effects of Na2O, TiO2, B2O3, and fluorine on key properties such as viscosity, crystallization temperature, and melting behavior. Analytical methods, including viscosity measurements, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM-EDS), combined with thermodynamic modeling, were used to evaluate performance. Four formulations were selected based on factorial design results. Sample A, with high Na2O, exhibited intense crystallization of merwinite (Ca3MgSi2O8) and perovskite (CaTiO3). Sample B, incorporating B2O3, had reduced crystallization and suitable viscosity (2.97 Pa·s). Sample C, with a slightly higher fluorine content than Sample B and without B2O3, presented balanced low viscosity (1.75 Pa·s) with a moderate crystallization tendency. Sample D, free of fluorine and B2O3, showed high viscosity (4.58 Pa·s) and significant crystallization. These results demonstrate that fluorine-free fluxes with properties comparable to fluorine-based compositions can be developed, offering a sustainable alternative for steelmaking. Industrial trials are necessary to validate their performance under operational conditions.

Ionic Conductivity and Viscosity Behavior of PMMA-based Nano-dispersed Polymer Gel Electrolytes Containing Lithium Perchlorate

Abstract: In this study, nano-dispersed polymer gel electrolytes containing polymethylmethacrylate (PMMA), lithium perchlorate (LiClO4), diethyl carbonate (DEC), dimethylacetamide (DMA), and nano-sized fumed silica (SiO2) have been synthesized and characterized. The electrolytes showed high ionic conductivity for electrolytes with higher dielectric constant solvents. The polymer enhanced the ionic conductivity of liquid electrolytes having a lower dielectric constant solvent (DEC) at all PMMA concentrations than the electrolytes containing a high dielectric constant solvent (DMA). Further, with the addition of nano-sized fumed silica, the ionic conductivity showed a small increase along with an increase in the mechanical stability of the electrolytes. The viscosity behavior of the electrolytes was also discussed, and it was correlated with the results of the ionic conductivity test. Nano-dispersed polymer gel electrolytes exhibited high ionic conductivity (10-2 S/cm). Further, the conductivity showed only a small change (by a factor, not by an order) over the 25-100°C temperature range and did not vary with time, which is desirable for their use in practical applications.

High Viscosity and Two Phases Observed over a Range of Relative Humidities in Biomass Burning Organic Aerosol from Canadian Wildfires.

Biomass burning organic aerosol (BBOA) is a major contributor to organic aerosol in the atmosphere. The impacts of BBOA on climate and health depend strongly upon their physicochemical properties, including viscosity and phase behavior (number and types of phases); these properties are not yet fully characterized. We collected BBOA field samples during the 2021 British Columbia wildfire season to constrain the viscosity and phase behavior at a range of relative humidities and compared them to previous studies on BBOA. Particles from all samples exhibited two-phased behavior with a polar hydrophilic phase and a nonpolar hydrophobic phase. We used the poke-flow viscosity technique to estimate the viscosity of the particles. Both phases of the BBOA had viscosities of >108 Pa s at relative humidities up to 50%. Such high viscosities correspond to mixing times within 200 nm BBOA particles of >5 h. Two phases and high viscosity have implications for how BBOA should be treated in atmospheric models.

Thermophysical Properties of the Hydrogen Carrier System Based on Aqueous Solutions of Isopropanol or Acetone

One concept for the safe storage and transport of molecular hydrogen (H2) is the use of hydrogen carrier systems which can bind and release hydrogen in repeating cycles. In this context, the liquid system based on isopropanol and its dehydrogenated counterpart acetone is particularly interesting for applications in direct isopropanol fuel cells that are operated with an excess of water. For a comprehensive characterization of diluted aqueous solutions of isopropanol or acetone with technically relevant solute amount fractions between 0.02 and 0.08, their liquid density, liquid viscosity, and interfacial tension were investigated using various light scattering and conventional techniques as well as equilibrium molecular dynamics (EMD) simulations between (283 and 403) K. Polarization-difference Raman spectroscopy (PDRS) was used to monitor the liquid-phase composition during surface light scattering (SLS) experiments on viscosity and interfacial tension. For comparison purposes and to expand the database, capillary viscometry and dynamic light scattering (DLS) from bulk fluids with dispersed particles were also applied to determine the viscosity while the pendant-drop (PD) method allowed access to the interfacial tension. By adding isopropanol or acetone to water, density and, in particular, interfacial tension decrease significantly, while viscosity shows a pronounced increase. The behavior of viscosity and interfacial tension is closely related to the strong hydrogen bonding between the unlike mixture components and the pronounced enrichment of both solutes at the vapor–liquid interface, as revealed by EMD simulations. For an aqueous solution with an isopropanol amount fraction of 0.04, minor variations in interfacial tension and viscosity were found in the presence of pressurized H2 up to 7.5 MPa. Overall, the results from this study contribute to an extended database for diluted aqueous solutions of isopropanol or acetone, especially at temperatures above 323 K.

Applying different machine learning algorithms to predict the viscosity behavior of MWCNT–alumina/water–ethylene glycol (80:20) hybrid antifreeze

While machine learning has become the new way of analyzing data, neutral networks form the basis of this revolutionary technology. In this work, we shall employ the power of neural networks to analyze and demystify the processes in nanofluids. By combining the precision of neural networks with the optimization capabilities of genetic algorithms, we aim to create a more accurate and efficient prediction model for MWCNT-alumina/water-ethylene glycol (80:20) hybrid antifreeze. Our approach entails using an MLP neural network and several training functions (LM, GD, BFGS, BN) with an adjustable number of neurons. The inputs of the network are φ (solid volume fraction or ϕ), temperature (T), and shear rate (γ), and the output is μnf of MWCNT-alumina/water-ethylene glycol (80:20) hybrid anti-freeze. To improve the accuracy of the final model, we use genetic optimization to make final adjustments to the parameters of the neural network. Utilizing the detailed analysis of the primary characteristics of these algorithms, we conclude that the BFGS function is the best to obtain neural network training. Steady performance achieved by this function—0.99828 of the R-value and RMSE value significantly equal to 0.213—illustrates good stability and accuracy of the suggested model. This work contributes to progressing the existing knowledge about the behavior of nanofluids and can stimulate further improvement in heat transfer and energy utilization.

Hydroxypropyl β Cyclodextrins Effects on Self-Assembly of Cyclic Peptide, Lanreotide Acetate, in Water and Subsequent Release rate from an in vitro Emulator of Subcutaneous Delivery

Most of peptide drugs are often delivered subcutaneously. The significant barrier in this type of peptide administration is the high concentration of formulation, which can lead to self-assembly and aggregation. These phenomena can negatively impact the bioavailability, manufacturing, and injectability of the peptide drug. This study investigated the self-assembly behavior of Lanreotide acetate at high concentration in water using Hydroxypropyl β- Cyclodextrins (HPβCyD) to mitigate the self-assembly and enhance release rate during subcutaneous administration. Our finding demonstrated that the lanreotide/ HPβCyD inclusion complex effectively prevents aromatic-aromatic interactions of lanreotide, thereby controlling self-assembly. This complexation also alters the viscosity behavior of lanreotide from non-Newtonian under low shear rates to Newtonian solution. Furthermore, the lanreotide/ HPβCyD inclusion complex reduces interactions with hyaluronic acid in the subcutaneous environment, leading to significant improvement in the release rate of lanreotide acetate at high concentrations (above 3% w/w in water).

Effect of deflocculants on the rheological behavior of high alumina matrix suspensions for self-flowing bauxite castable

This study investigates the influence of commercially available polyphosphates and polycarboxylate ethers as deflocculants on aqueous suspensions containing high alumina cement (HAC), reactive alumina (RA), and various matrix compositions. Utilizing rheological methods, the research explores the interplay between dispersant concentration and the apparent viscosity and flow behavior of RA suspensions and matrix mixtures. The Casson model is employed to effectively describe the obtained flow data. Moreover, the study discerns specific impacts of polycarboxylate ethers on the thickening properties of matrix mixtures characterized by varying RA and HAC contents. Additionally, the research evaluates the physical and mechanical properties of low-cement bauxite castables treated with a range of polycarboxylate esters. The findings demonstrate that all deflocculated suspensions exhibit Non-Newtonian structured fluid behavior with a discernible yield stress (τ0) at shear rates below 20 s-1. At higher shear rates, there is a significant reduction in apparent viscosity, aligning well with the Casson model. Comparative assessments, based on flow curve values τ0, elucidate differing degrees of suspension flocculation depending on the type of dispersant used.

Double-Network Hydrogel 3D BioPrinting Biocompatible with Fibroblast Cells for Tissue Engineering Applications.

The present study examines the formulation of a biocompatible hydrogel bioink for 3D bioprinting, integrating poly(ethylene glycol) diacrylate (PEGDA) and sodium alginate (SA) using a double-network approach. These materials were chosen for their synergistic qualities, with PEGDA contributing to mechanical integrity and SA ensuring biocompatibility. Fibroblast cells were included in the bioink and printed with a Reg4Life bioprinter employing micro-extrusion technology. The optimisation of printing parameters included needle size and flow velocities. This led to precise structure development and yielded results with a negligible deviation in printed angles and better control of line widths. The rheological characteristics of the bioink were evaluated, demonstrating appropriate viscosity and shear-thinning behaviour for efficient extrusion. The mechanical characterisation revealed an average compressive modulus of 0.38 MPa, suitable for tissue engineering applications. The printability of the bioink was further confirmed through the evaluations of morphology and diffusion rates, confirming structural integrity. Biocompatibility assessments demonstrated a high cell viability rate of 82.65% following 48 h of incubation, supporting the bioink's suitability for facilitating cell survival. This study introduced a reliable technique for producing tissue-engineered scaffolds that exhibit outstanding mechanical characteristics and cell viability, highlighting the promise of PEGDA-SA hydrogels in bioprinting applications.

Towards cleaner machining: Experimental investigation of collagen-in-water as a novel type of metalworking fluids – A technical feasibility study

Driven by environmental challenges, health concerns and increasing legislative restrictions, a high demand for research regarding alternative metalworking fluids (MWFs) to substitute the conventional mineral oil-containing fluids emerges. In recent years, bio-based fluids have continuously gained attention, as their usage could mitigate the disadvantages of conventionally used fluids, which usually contain mineral oil. Against this background, this research aims to contributing towards biological MWFs by investigating the technical applicability of collagen-in-water fluids through evaluations and comparisons with conventional MWFs. The analyzed bio-based MWF is based on collagen-hydrolysate powder dissolved in water, with collagen acting as a viscosity-increasing additive. The prepared fluids were investigated regarding their viscosity and tribological behavior in cylinder-on-ring experiments as well as tapping-torque tests. Afterwards, first machining experiments were performed for honing and grinding of hardened steel. Force-led cylinder-on-ring experiments show a significant wear reduction, e.g. a value of 13.4 mm2 at 3 wt.% collagen compared to 33.0 mm2 with pure distilled water. Wear further decreased with increasing collagen content. At 3 wt.% and again compared to pure water, tapping torque was reduced by 29 % to 181.7 Ncm, no further torque reduction was observed with increasing collagen concentration. In honing, roughness was reduced using collagen-in-water, however, an 8 wt.% collagen fluid resulted in an 18 % reduction in material removal rate compared to honing oil. In internal grinding, an 8 wt.% collagen fluid achieved an Ra of approximately 0.8 μm, compared to around 0.55 μm with emulsion. The application results demonstrate a high potential for collagen-in-water fluids, however, adjustments are necessary for obtaining competitive fluids.

Effect of shear rate, temperature, and salts on the viscosity and viscoelasticity of semi‐dilute and entangled xanthan gum

AbstractXanthan gum, a naturally‐occurring, high‐molecular‐weight, anionic polyelectrolyte, exhibits significant drag‐reducing properties at low concentrations in water, suggesting promising applications in geothermal networks. The flow behavior of xanthan solutions are explored, specifically at concentrations in the semi‐dilute (1000 ppm by mass) and entangled (4000 ppm) regimes as well as in both water and various salt solutions across a temperature range of 5–85°C. The viscosity and viscoelastic properties of xanthan solutions examine relationships between polyelectrolyte concentration, temperature, and salt concentration. Viscosity decreases by two orders of magnitude in 4000 ppm xanthan solutions in deionized water and with 50 mM NaCl (in the high salt limit) as the temperature increases from 5 to 85°C. Next, the addition of salts affects viscosity differently in the two concentration regimes. Specifically, at 25°C, the zero‐shear rate viscosity upon salt addition decreases by 63% for 1000 ppm solutions (from 0.54 to 0.2 Pa s) but increases by 280% for 4000 ppm solutions (from 28 to 107 Pa s). At 1000 ppm, salt ions cause chain collapse, reducing viscosity; At 4000 ppm, entanglements led to structural changes, resulting in higher viscosity. Furthermore, three salts commonly found in geothermal waters, namely NaCl, Na2CO3, and NaHCO3, exhibited similar changes in viscosity and shear thinning behavior in the entangled regime across temperatures from 5 to 85°C.

Beyond the Surface: Interconnection of Viscosity, Crystal Growth, and Diffusion in Ge25Se75 Glass-Former.

The knowledge of viscosity behavior, crystal growth phenomenon, and diffusion is important in producing, processing, and practical applications of amorphous solids prepared in different forms (bulk glasses and thin films). This work uses microscopy to study volume crystal growth in Ge25Se75 bulk glasses and thermally evaporated thin films. The collected growth data measured over a wide temperature range show a significant increase in crystal growth rates in thin films. The crystal growth is analyzed using near-surface viscosities obtained in bulks and thin films using nanoindentation and melt viscosities measured by a pressure-assisted melt filling technique. The crystal growth analysis provides information on the size of the structural units incorporated into the growing crystals, essential for estimating the diffusion coefficients and explaining the difference in crystal growth rates in bulk and thin films. The crystal growth analysis also reveals the decoupling between diffusion and viscous flow described by the Stokes-Einstein-Eyring relation. Moreover, to the authors' best knowledge, the manuscript provides the first evaluation estimation of the effective self-diffusion coefficient directly from growth data in chalcogenide glass-formers. The present data show a similar relation between diffusion coefficients (D) and crystal growth rates (u): u ≈ D0.87, which is found in several molecular glasses.