Viscosity Behavior Research Articles

Free volume theory explains the unusual behavior of viscosity in a non-confluent tissue during morphogenesis.

A recent experiment on zebrafish blastoderm morphogenesis showed that the viscosity (η) of a non-confluent embryonic tissue grows sharply until a critical cell packing fraction (ϕS). The increase in η up to ϕS is similar to the behavior observed in several glass-forming materials, which suggests that the cell dynamics is sluggish or glass-like. Surprisingly, η is a constant above ϕS. To determine the mechanism of this unusual dependence of η on ϕ, we performed extensive simulations using an agent-based model of a dense non-confluent two-dimensional tissue. We show that polydispersity in the cell size, and the propensity of the cells to deform, results in the saturation of the available free area per cell beyond a critical packing fraction. Saturation in the free space not only explains the viscosity plateau above ϕS but also provides a relationship between equilibrium geometrical packing to the dramatic increase in the relaxation dynamics.

Free volume theory explains the unusual behavior of viscosity in a non-confluent tissue during morphogenesis

A recent experiment on zebrafish blastoderm morphogenesis showed that the viscosity (η) of a non-confluent embryonic tissue grows sharply until a critical cell packing fraction (ϕS). The increase in η up to ϕS is similar to the behavior observed in several glass-forming materials, which suggests that the cell dynamics is sluggish or glass-like. Surprisingly, η is a constant above ϕS. To determine the mechanism of this unusual dependence of η on ϕ, we performed extensive simulations using an agent-based model of a dense non-confluent two-dimensional tissue. We show that polydispersity in the cell size, and the propensity of the cells to deform, results in the saturation of the available free area per cell beyond a critical packing fraction. Saturation in the free space not only explains the viscosity plateau above ϕS but also provides a relationship between equilibrium geometrical packing to the dramatic increase in the relaxation dynamics.

Multi-effect of fineness and replacement ratio of binders on thixotropic and some fresh state properties of cementitious systems, a comparative study

Effects of cement fineness, fly ash replacement ratio and fineness changes on some fresh state and rheological properties of mixtures were investigated in this study. Two different Blaine finenesses of portland cement (4000, 5000 cm2/g) and 4 different finenesses of fly ash (4000, 5000, 6000 and 7000 cm2/g) were used. 26 different paste mixtures were prepared by substituting fly ash in 3 different ratios (10%, 20%, and 30%) by weight. Marsh-funnel flow time, mini-slump, setting time, dynamic yield stress (DYS), viscosity and thixotropic behavior of mixtures were investigated. 4 different thixotropy measurement methods were used; dynamic yield stress ratio (DYSR), viscosity ratio (VR), shear stress-structural build-up area (SBUshr) and viscosity-structural build-up area (SBUvis). There was no notable change in the initial setting time results of the mixtures with the increase in portland cement fineness. The rheological parameters and thixotropic behavior of the mixtures increased significantly. Vicat-water requirement and setting-time-value decreased with the increase of fly ash fineness in cementitious mixtures with low fineness. The structural build-up of the mixtures decrease with the rise of the F class FA replacement ratio. It was determined that the methods with the highest correlation among thixotropy measurement methods were SBUshr-SBUvis, DYSR-SBUshr and DYSR-Athix, respectively.

Effect of particle gradation on the properties of Mg(OH)2 slurry: viscosity, stability, and rheology

In this article, multipeak Mg(OH)2 slurries, that is, unimodal, bimodal, and trimodal, were prepared by blending Mg(OH)2 of distinct particle sizes (d 50 of 1, 3, 7, 10, and 20 μm). The effects of particle gradation on the properties of Mg(OH)2 slurry, such as viscosity, stability, and rheological behavior, were investigated. Also, the packing efficiency was analyzed by the compartment packing model. The results revealed that viscosity and stability decrease with particle size or larger particle mixing in unimodal and bimodal schemes. However, trimodal slurry viscosity did not significantly change with particle size ratio. The packing efficiency calculated by the compartment packing model has the opposite trend of viscosity, but this trend is not so strictly consistent in the three-peak gradation scheme. Among the unimodal, bimodal, and trimodal slurries with better viscosity and stability (10, 3 + 10 (3:7), and 1 + 7 + 10 μm (3:1:6)), the trimodal slurry had the lowest viscosity and the highest stability. Its highest yield stress (4.66 ± 0.23 Pa) and flow stress (7.67 ± 0.38 Pa) indicated its structural stability, and it showed good structural recovery capability, reestablishing about 87% in 60 seconds. This might be explained by the fine particles forming a bridge between the coarse particles, resulting in a stable and networked structure.

Bio-based nanomaterial suspensions as sprayable coatings for maintaining blueberry postharvest quality

The growing concerns about postharvest fruit spoilage demand sustainable active coating materials with high performance. In this work, bioactive spray coating suspensions were developed for the postharvest preservation of blueberries using chitosan, cellulose, and lignocellulose nanofibers (ChNFs, CNFs, and LCNFs), sodium alginate (SA), and tea tree essential oil (TTO). Characteristics, including the rheological properties of coatings and the effect on physicochemical postharvest quality parameters of blueberry fruit were investigated. The nanomaterials and SA were shown to make stable and sprayable coating suspensions with high surface charge (zeta potential value of −61.3 mV), shear thinning behavior, steady viscosity, and outstanding viscoelastic behavior from their ability to restore fibrous network structure and ion strength of SA to inhibit nanofibers aggregation. The coatings with LCNFs and SA were more effective in retarding moisture loss of postharvest blueberries during storage compared with coatings without LCNFs and SA. Blueberries coated with ChNF/LCNF/SA/TTO had a soluble solids content (SSC) increase of 16.2% after 15 storage days, while uncoated and other coated blueberries had more than a 21.7% SSC increase. In addition, the ChNF/LCNF/SA/TTO coating had an entangled matrix structure and enhanced hydrophobicity, improving gas barrier performance on the blueberry surface. As a result, the coating was able to preserve the moisture, stiffness, firmness, and individual sugar contents of blueberries during storage. Utilizing nanomaterials and other natural polysaccharides in coatings can offer an economically feasible and sustainable approach for functionalizing biomass materials to preserve fruits.

Effect of clay crystal structure on froth rheology in flotation

It has been well acknowledged that clay minerals could impose deleterious effects on flotation performance by affecting pulp rheology. To date, it is still not clear regarding the role of clay minerals in influencing froth rheology which has been increasingly recognized as an important froth property in determining flotation performance. Hence, this work selected three typical clay minerals with different characteristics to study their impacts on froth rheology: montmorillonite, kaolinite and talc. The results showed that the clay minerals showed different froth rheological behaviors with increasing the solids concentration in the feed from 1 wt% to 9 wt%. For montmorillonite, the froth viscosity decreased first and then increased, reaching a lowest viscosity at 5 wt%. The froth viscosity continuously decreased for kaolinite while it kept increasing for talc over the solids concentration in the feed. In addition, talc generated much more viscous froths than the other two clays. The different varying behaviors of froth viscosity among the three clays were related to clay crystal structure and surface hydrophobicity which ultimately determined froth properties. It is believed that the outcomes of this study could facilitate the flotation optimization of complex ores with the presence of clay minerals.

Characteristics of novel cycloaliphatic epoxides based on UV-induced cationic ring-opening polymerization for plastic coatings

Cationic ring-opening polymerization (CROP)-capable cycloaliphatic epoxide monomers bearing a benzyl ether group (CE-BEs) were developed as glass-replacement plastic coatings for lightweight automobiles. Three different monomers of bis(((7-oxabicyclo[4,1,0]heptan-3-yl)methoxy)methyl)benzene isomers were synthesized to provide the cycloaliphatic epoxide functional groups. 1H and 13C nuclear magnetic resonance and Fourier transform infrared (FT-IR) spectroscopic analyses confirmed that the monomers were successfully synthesized. The shear viscosity and real-time crosslinking behavior of the CROP coatings were investigated using a rheometer. In particular, the release of thermal energy via CROP under UV irradiation was monitored using differential scanning photocalorimetry. The reaction conversion of cycloaliphatic epoxides by CROP before and after UV irradiation was verified using FT-IR spectroscopy. The transparency of the CROP coating films cured on a polycarbonate substrate was measured using an ultraviolet–visible spectrophotometer, and their adhesion was confirmed using cross-cut tests. For characterization of the surface mechanical properties, a nanoindentation tester and a nanoscratch tester were used in conjunction with an atomic force microscope to evaluate the surface hardness and scratch resistance, respectively. In addition, the thermomechanical properties of the cured CROP coating films were investigated using a rigid-body pendulum tester operated in dynamic physical mode. The ternary coating systems with CE-BEs were found to exhibit high photoreactivity, a dense crosslinking density, a transparent appearance, and enhanced adhesion and mechanical properties, making it suitable for glass-replacement plastic coatings.

Additive manufacturing of novel lightweight insulation refractory with hierarchical pore structures by direct ink writing

A direct ink writing process using fly ash foaming slurries was employed for the additive manufacturing of lightweight mullite insulation refractory with hierarchical pore structures. The viscosity, thixotropy, and shear thinning behavior of the inks were analyzed to investigate the effect of the inorganic binder and dispersant of the foaming inks. A slurry exhibiting excellent rheological characteristics was identified, consisting of 45 wt% fly ash floating beads, 55 wt% water, 3.0 wt% additional dispersant, and 6.0 wt% additional binder. Furthermore, through the optimization of printing parameters such as printing pressure and printing speed, notable enhancements were achieved in the pore structure and properties of the final insulation refractory. Upon heating the lightweight insulation refractory to 1300 °C, the bulk density, compressive strength, and thermal conductivity were determined to be 0.61 g/cm3, 1.01 MPa, and 0.13 W/(m·K), respectively. The direct ink writing technique demonstrates substantial potential in manufacturing lightweight refractories that possess superior thermal insulation and reliable usage strength.

The Field-Dependent Magnetic Viscosity of FeNdB Permanent Magnets.

The time-dependent decrease of the magnetic polarization of magnet materials in the presence of an opposing field is well known as the magnetic viscosity or magnetic aftereffect. In previous studies, magnetic viscosity was usually measured in fields when in the vicinity of coercivity HcJ, and this was conducted in order to understand the coercivity mechanism in magnetic materials. In this study, the magnetic viscosity of commercial FeNdB magnets is determined at opposing fields weaker than HcJ and at different temperatures in the range from 303 to 433 K (i.e., from 30 to 160 °C) by means of a vibrating sample magnetometer (VSM). As a result, the parameter Sv, which describes the magnetic viscosity in the material, was found to increase with increases in the opposing field. Furthermore, both the parameter Sv and its dependence on the temperature were found to correlate with the coercivity HcJ of the material. Also, a difference with regard to the parameter Sv for the materials measured in this study with similar magnetic properties, but which had undergone different types of processing, could not be found. Knowledge of the field- and temperature-dependent behavior of the magnetic viscosity of FeNdB magnets allows for better estimations over the lifetime of a component under operating conditions with respect to the magnetic losses in FeNdB magnets that are used in electric components.

A yeast-malic acid crosslinker/polyacrylic acid hydrogel containing doxycycline for the treatment of periodontitis.

Doxycycline (DX) is a drug of choice for the treatment of periodontitis, with the limitation of requiring a high dose, which may be overcome by the preparation of a targeted controlled-release hydrogel containing a newly synthesized yeast-malic acid crosslinker (YMC). YMC was synthesized via thermochemical modification of yeast with malic acid at 100-140 °C and compared with glutaraldehyde-saturated toluene (GST). Swelling capacity, acid and carboxyl content, scanning electron microscopy (SEM) imaging, Brunauer-Emmett-Teller (BET) analysis, viscosity, cross-linking density, DX loading and release behavior at pH 6.5, mucoadhesion, and antimicrobial and periodontal efficacy of the glutaraldehyde hydrogel (HGG) and YMC hydrogel (HGY) were compared. Changes from C-O (1421 cm-1) to C[double bond, length as m-dash]OOR (1702 cm-1) in the infrared spectroscopy, along with changes in the degree of substitution from 0 to 0.39, degree of esterification from 0 to 40 ± 1.5 and COOH content from 129 ± 0.5 to 290 ± 0.5 (meq. per 100 g), were found between yeast to YMC, respectively. The results revealed 1.5 times more dynamic swelling, 0.25-fold decrease in acid content, 2.3-fold increase in carboxyl content, and 1.2- and 2.1-fold increases in cross-linking density and viscosity of HGY as compared to HGG, respectively. The SEM and BET results revealed that HGY had a 2 times greater porous surface than HGG. HGY/DX was 35 ± 2% more effective in controlling periodontitis bacteria, decreased periodontal depth from 4 to 3.2 mm, and gingival index from 3 to 1 as compared to HGG/DX in patients suffering from periodontitis. HGY/DX not only serves as a tool for the controlled release of DX in periodontal pockets but also contributes to the treatment of gingival periodontitis.

Repeated mechanical recycling of biodegradable polymers: PLA exhibits less deterioration than PBAT/PLA blend

Biodegradable polymers have been extensively researched as alternatives to non-biodegradable fossil-based polymers. Although they reduce environmental impact, their production competes with land needed for food crops. Therefore, exploring their reuse and recycling is essential for enhancing their circular economy and sustainability. This study evaluated the recyclability of commercially available biodegradable polymers, poly (lactic acid) (PLA) and its blend with poly (butylene adipate co-terephthalate) (PBAT), across three cycles of mechanical recycling. Each cycle simulates plastic production, shelf-life, washing, and reprocessing stages. Samples were analysed after molding, ageing, and washing for each cycle using Differential Scanning Calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), tensile testing, and rheological analysis to track changes in crystallization, chemical structure, viscosity, and mechanical behaviors. Results indicated that both PLA and PBAT/PLA (55/45 wt%) blend showed a rise in crystallinity (Xc) due to the annealing effect of the ageing and washing. No changes in FTIR spectra and Xc were detected after one recycling cycle, indicating stability. After three reprocessing cycles, second heating crystallinity rose from 2 % to 13 % for PLA and from 2 % to 12 % for PBAT/PLA (45 wt% PLA), indicating morphological changes from degradation and molecular weight reduction. Despite higher crystallinity and a more moderate decline in complex viscosity and storage modulus than PLA, PBAT/PLA showed reduced mechanical properties, with a 90 % drop in elongation at break and nearly 50 % in stress at break, highlighting the need for interventions to control PBAT degradation. PLA maintained strong mechanical properties, demonstrating its potential as a compostable recyclable material.

Behavior of Pasting Properties of Ohmic‐Heated Corn Starch Versus Moisture and Temperature Applied

AbstractStarch is an essential biopolymer for creating viscous food systems in the food industry. Viscosity behavior is unclear in the literature and varies with the thermal process and moisture content used. This study analyzed how ohmic heating affects the pasting properties of corn starch in response to changes in moisture and temperature. Corn starch is mixed with water at varying ratios (1:1, 1:3, and 1:5). The mixture is heated at 5 °C min−1 using an ohmic heating cooker to 80, 100, and 120 °C. Moisture affects pasting and starch properties. Peak viscosity varies with moisture content, decreasing from 5904 cP (native) to 3204–4510 cP at a 1:1 ratio. At a moisture ratio of 1:3, peak viscosity matched the native sample. Higher peak viscosity (6539 to 8772 cP) occurred at high moisture levels (1:3). Thermal properties confirmed different gelatinization degrees, which is evidenced by a shift in the x‐ray diffraction pattern from A‐type (native starch) to V‐type crystalline. The viscosity and physicochemical properties of corn starch depend on temperature and moisture levels. Moisture has a more significant impact on these properties than temperature. Therefore, varying the moisture content it can improve corn starch properties precisely, making it useful for the food industry.

Structural, physicochemical, and pasting properties of native cassava (Manihot esculenta) and yam (Dioscorea alata) starch blends

Starch blends are a technological alternative aimed at the development of starchy matrices that exhibit improvements in some physicochemical properties from interactions between their individual components. Native cassava and yam starches were mixed in different proportions and the effect of the blend on the structural, physicochemical, and pasting properties was evaluated. The viscosity behavior as a function of temperature revealed a significant non-additive effect on the pasting parameters of all the blends with respect to the individual native starches. Similarly, non-additive variations were evident in the crystallinity index of some mix ratios (NSB-2: 40.11%). Likewise, the difference in the amylose content of each native starch (20.88-25.66%) possibly exerted an effect on the resulting semicrystalline characteristics of the blends and the gelatinization behavior. Hence, the botanical origin and the proportion of starch blends play an important role in the behavior of the resulting physicochemical properties and in vitro digestibility. Polymeric blends were obtained with a low tendency to retrogradation and lower crystallinity index values compared to their native counterparts and a regulated water absorption capacity, all potentially desirable characteristics in the food industry.

Comparative Study on Transport Property of Asymmetric Fluorosulfonyl(trifluoromethylsulfonyl)Amide-Based Phosphonium Ionic Liquids

Room-temperature ionic liquids (RTILs), i.e. organic molten salts with melting points below ambient temperature, have been regarded as potential electrolytes for various electrochemical systems, because RTILs have unique physicochemical properties such as favorable solubility of organic and inorganic compounds, relatively high ionic conductivity, no measurable vapor pressure, high thermal stability, low flammability, etc. The quaternary phosphonium cation based RTILs have attracted attention in recent years due to their high chemical and thermal stabilities. We have proposed and synthesized a class of low viscous and highly conductive RTILs based on triethylalkylphosphonium cations in combination with typical sulfonylamide-based anions, e.g. bis(trifluoromethylsulfonyl)amide (N(SO2CF3)2 -, TFSA) and bis(fluorosulfonyl)amide (N(SO2F)2 -, FSA) anions.1,2 Our recent approaches include a design and synthesis of low-melting phosphonium based RTILs together with asymmetric fluorosulfonyl(trifluoromethylsulfonyl)amide (N(SO2F)(SO2CF3)-, FTA) anion. In this work, we report the transport property and unique viscosity behavior of several FTA anion based phosphonium RTILs as shown Fig. 1. The FTA-based phosphonium RTILs was synthesized by aqueous ion exchange reaction of the precursor quaternary phosphonium halides with lithium FTA. The crude RTILs obtained were hydrophobic and purified by washing with pure water several times in order to remove residual metal and halide ions. The RTILs thus prepared were dried under high vacuum for at least 1 day. The physicochemical properties of RTILs, e.g. density, viscosity, conductivity (ac impedance method), were measured at elevated temperatures under argon atmosphere.Several low-melting phosphonium RTILs were successfully prepared by combination with FTA anion (P2225, P2228 and P4441-FTA). All FTA-based phosphonium RTILs showed typical temperature dependent behaviors for density, viscosity and electrical conductivity. The conductivities of FTA-based phosphonium RTILs were higher and lower than those of corresponding TFSA- and FSA-based phosphonium RTILs, respectively; however, it should be noted that the viscosities of FTA-based phosphonium RTILs were the lowest in the phosphonium RTILs as depicted in Fig. 2. To our knowledge, such a unique viscosity behavior has not been previously reported in the FTA-based ammonium based RTILs. The detailed transport property and electrolytic behaviors such as the Arrhenius plots of viscosity and conductivity with VTF fitting and the Walden plots will be also discussed in comparison with both corresponding TFSA- and FSA-based RTILs.References1) K. Tsunashima, et al, Electrochem. Commun., 9, 2353 (2007).2) K. Tsunashima, et al, Electrochem. Commun., 13, 178 (2011). Figure 1

Experimental validation for the interconversion between generalized Kelvin–Voigt and Maxwell models using human skin tissues

Mechanical properties of biological systems provide essential insights into their component, physiological function, and disease mechanism under various conditions, such as age, health, and other environmental factors. Viscoelasticity is one of the most important and investigated properties to study biomaterials, cells, and tissues, as they exhibit the characteristics of both fluid-like behavior, viscosity, and solid-like behavior, elasticity. Various mathematical models, such as the Kelvin–Voigt and Maxwell models, have been developed and practiced to estimate and extract viscoelastic properties. However, one of the inherent challenges with the use of these models is the poor transferability of mathematically estimated viscoelastic properties across different models, largely due to variations in constituent elements and their arrangements within each model. This issue impedes the interconversion of parameters of one model to another and complicates comparison across models. In this study, we demonstrate the equivalence between the generalized Maxwell and generalized Kelvin-Voigt models through two distinct approaches: indirect, Maxwell model-based Kelvin-Voigt model estimation and direct, curve fitting-based Kelvin-Voigt model estimation. We utilized human melanoma skin tissues to estimate viscoelastic properties using the Prony series. The estimated parameters and resulting viscoelastic properties revealed no significant difference between the two approaches and between the two patients. This study is the first experimental validation of the mathematical interconversion of the two models, signifying that this approach will enable an accurate and objective analysis and comparison of mechanical properties across various viscoelastic models.

Improved crystallization behavior and enhanced impact strength of melt processed poly(ethylene terephthalate)/UiO-66 nanocomposites

The present research aimed to investigate the influence of Zr-based metal-organic framework, i.e. UiO-66, on the performance of poly(ethylene terephthalate) (PET) by the melt mixing method. PET/UiO-66 nanocomposites were prepared at 0.25, 0.5, 1, and 2 wt% of UiO-66. FESEM microphotographs showed the success of the melt mixing method in the fine dispersion of UiO-66 within PET. Additionally, XRD patterns confirmed that UiO-66 retained its structure after melt mixing at 260 °C. DSC analysis suggested that UiO-66 acted as a nucleating agent with a best performance at 1 wt% loading, i.e. 45 % decrease in the crystallization half-time and 11 % increase in the crystallization temperature. Furthermore, the PET/UiO-66 nanocomposites exhibited an improvement in char formation and resistance to complete thermal degradation at high temperatures compared to neat PET. The inclusion of UiO-66 in PET increased the impact strength with a maximum value at 0.5 wt% loading, e.g. more than twice neat PET. In addition, DMTA results indicated that UiO-66 acted as a strengthening agent in PET. Rheological investigations revealed that PET/UiO-66 exhibits the non-Einstein-like viscosity behavior in which the complex viscosity decreased by increasing UiO-66 content. We reasoned that behavior mainly to the flexible nature of the UiO-66 particles. Although all the samples showed almost Newtonian behavior at 260 °C in frequencies between 0.03 Hz and 100 Hz, PET/UiO-66 (0.5) presented the shear thinning behavior. This was ascribed to the good dispersion with the strong interfacial interaction, leading to a microstructure with yield stress.

Application of single and multi-solid phase STFs to Twaron fabrics: evaluation of energy absorption performances

The present study aims to enhance the energy absorption performance of Twaron aramid fabrics by impregnating them with single and multi-solid phase shear thickening fluids (STFs). To investigate the energy absorption capacity of Twaron 200 and Twaron 460 fabrics, surface friction, yarn tensile, and ballistic tests have been performed. Silicon carbide (SiC), graphene nanoplate (GNP), and carbon nanotube (CNT) are utilized both individually and in hybrid forms to examine the impact of multi-solid phase STFs. The research reveals that STFs reinforced with SiC and GNP exhibit higher viscosity and rheological behavior compared to other hybrid nanoparticles. The addition of SiC and GNP reinforced STF (STF/SiC + GNP) suspension significantly increases the friction coefficient by approximately 82% for Twaron 200 and 120% for Twaron 460 in comparison to neat fabric. Moreover, the maximum yarn tensile strength of Twaron 460 is higher than that of Twaron 200 in both neat and STF impregnated fabrics. The research also states that STF impregnation procedure improves the ballistic performance of neat fabrics in both fabric types. The ballistic test results show an increase in the protective performance of STF impregnated fabrics reinforced with nanoparticles. The best ballistic performance is found in STF/SiC + GNP impregnated fabrics in Twaron 200 and Twaron 460 samples.

Obtaining an accurate prediction model for viscosity of a new nano-lubricant containing multi-walled carbon nanotube-titanium dioxide nanoparticles with oil SAE50

This study aims to investigate the viscosity behavior of multi-walled carbon nanotube (MWCNT) - titanium dioxide (TiO2) (40−60) - SAE50 oil nanofluid using an Artificial Neural Network (ANN) modeling approach. The main objective is to develop a highly accurate predictive model for viscosity by considering three input parameters: temperature, solid volume fraction (SVF), and shear rate (SR). Rheological measurements provide experimental data used to train and validate the ANN model. The ANN model's architecture, activation functions, and training algorithms are carefully chosen. Data are divided to three subsets including train, validation and test. ANN is trained using trainlm algorithm for 50 times to vanish the effect of random nature of ANN weight initialization. The trained ANN model is then utilized to predict the viscosity of the nanofluid under varying conditions. The results demonstrate the efficacy of the proposed ANN model in capturing the complex relationship between viscosity and the input parameters, providing accurate viscosity predictions for the MWCNT-TiO2-oil SAE50 nanofluid. Furthermore, the influence of temperature, SVF, and SR on viscosity is analyzed, offering valuable insights into the flow behavior of the nanofluid. According to the obtained results, the developed ANN model presents a reliable and efficient approach to estimate the viscosity of the MWCNT-TiO2-SAE50 oil nanofluid, eliminating the need for costly and extensive experimental measurements within the analyzed range. ANN could model the nanofluid viscosity with R2 = 0.9998 and MSE= 0.000189 that is quite acceptable. Also, the experimental data revealed that for the investigated nanofluid, temperature and shear rate have impressive effect on the viscosity (changing viscosity more than 100% for the analyzed margin), on the other hand, the nanoparticle volume fraction effect is much lower, to be more precise, increasing the nanoparticle percentage will increase the viscosity mean value around 30%.

Physico-chemical characterisation of glycerol- and ethylene glycol-based deep eutectic solvents

Deep eutectic solvents are of significant interest to numerous applications including cryopreservation, chemical synthesis, lubrication, energy storage, catalysis, and self-assembly. However, to date there have been few rigorous and systematic studies of the physico-chemical and thermal properties of these solvents. This means that conclusive structure-function relationships are difficult to define within the context of the current literature. Here, we present the viscosity, refractive index, density, surface tension, and thermal behaviour of mixtures of either glycerol or ethylene glycol with choline chloride, betaine, or L-proline, as neat fluids and in the presence of water. We demonstrate that changing the ratio of hydrogen bond donor to hydrogen bond acceptor has only a small effect on the physico-chemical properties, while the addition of even small quantities of water has a significant effect. Despite rigorous studies, we demonstrate that determining the eutectic point of these mixtures is not straight-forward and that the definition of a ‘deep’ eutectic solvent may need to be reviewed in the frame of ideal mixing theory.

Glycerol/organic acid-based ternary deep eutectic solvents as a green approach to recover chitin with different molecular weight from seafood waste

In this study, we designed a green and efficient approach for the fractionation of high-purity chitin with tunable molecular weights from seafood waste. This was achieved by using ternary deep eutectic solvents (TDESs) composed of choline chloride as a hydrogen bond acceptor, glycerol as the polyol-based hydrogen bond donor, together with lactic acid or malic acid. Two binary DESs and four TDESs were evaluated for their ability to recover chitin. The extracted chitin exhibited not only high yield with excellent protein and mineral removal, but also high purity with similar crystallinity patterns as standard chitin. However, the average molecular weights, viscosity behavior and morphology of chitin extracted by DESs were varied and influenced by organic acid to glycerol molar ratios. The molecular weights of chitin extracted by lactic acid-based TDES ranged from 264 kDa to 541 kDa, but malic acid-based TEDS displayed a stronger depolymerization effect, resulting in chitin with a smaller molecular weight of less than 300 kDa. Lactic acid-based TDES revealed that the purity of chitin remained higher than 92 % after three cycles. This sustainable and environmentally friendly extraction system holds great potential to recover chitin from seafood waste, opening a new era for chitin extraction and applications.