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Black liquor (BL) is the major bioproduct and biomass fuel in pulp mill processes. However, the high viscosity of BL makes it a challenging material to work with, resulting in issues with evaporators and heat exchangers during its transport and processing. The thermal and rheological properties of BLs from Pinus sp. (PBL) and Eucalyptus sp. (EBL) were studied. FTIR spectra revealed the presence of the characteristic functional groups and the chemical composition in liquors. TGA/DTG curves showed three characteristic degradation stages related to evaporation of water, pyrolysis of organic groups, and condensation of char. Rheologically, liquors are classified as non-Newtonian and with comportment pseudoplastic. Their rheological dynamic shear properties included a linear viscoelastic region up to 1% shear strain, while frequency sweeps showed that storage modulus (G') > loss modulus (G''), thus confirming the solid-like behavior of both BLs. The rheological study demonstrated that increasing the temperature and oscillatory deformations of PBL and EBL decreased their degree of viscoelasticity, which could favor their pumping and handling within the pulp mill, as well as the droplet formation and swelling characteristics in the recovery furnace.

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OBJECTIVE: Tortuous microvessels are characteristic of microvascular remodeling associated with numerous physiological and pathological scenarios. Three-dimensional (3D) hemodynamics in tortuous microvessels influenced by red blood cells (RBCs), however, are largely unknown, and important questions remain. Is blood viscosity influenced by vessel tortuosity? How do RBC dynamics affect wall shear stress (WSS) patterns and the near-wall cell-free layer (CFL) over a range of conditions? The objective of this work was to parameterize hemodynamic characteristics unique to a tortuous microvessel. METHODS: RBC-resolved simulations were performed using an immersed boundary method-based 3D fluid dynamics solver. A representative tortuous microvessel was selected from a stimulated angiogenic network obtained from imaging of the rat mesentery and digitally reconstructed for the simulations. The representative microvessel was a venule with a diameter of approximately 20 µm. The model assumes a constant diameter along the vessel length and does not consider variations due to endothelial cell shapes or the endothelial surface layer. RESULTS: Microvessel tortuosity was observed to increase blood apparent viscosity compared to a straight tube by up to 26%. WSS spatial variations in high curvature regions reached 23.6 dyne/cm2 over the vessel cross-section. The magnitudes of WSS and CFL thickness variations due to tortuosity were strongly influenced by shear rate and negligibly influenced by tube hematocrit levels. CONCLUSIONS: New findings from this work reveal unique tortuosity-dependent hemodynamic characteristics over a range of conditions. The results provide new thought-provoking information to better understand the contribution of tortuous vessels in physiological and pathological processes and help improve reduced-order models.

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This study investigated the relationship between rheological properties, sensory perception, and overall acceptability in healthy young and old groups for dysphagia thickened liquids. Unflavored (UTL) and flavored (FTLP) thickened liquids were prepared using tap water or pomegranate juice at 10 different viscosity levels. The rheological properties were then evaluated via syringe flow test and line spread test (LST). When the apparent viscosity levels of UTL and FTLP were similar, the syringe test and LST results were also similar, indicating consistent flow behavior. Sensory perception evaluations showed that the young group better distinguished viscosity differences between stages compared to the old group. Regarding overall acceptability, the old group preferred samples with higher apparent viscosity than the young group. Principal component analysis and k-means cluster analysis were used to explore correlations between variables and classify thickened liquids into four groups. This can serve the foundation for standardized texture grades of dysphagia thickened liquids, considering rheological characteristics and sensory profiles.

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OBJECTIVES: 1) Identify processes limiting the arrival of itraconazole at the intestinal epithelium when Sporanox® amorphous solid dispersion (ASD) pellets are transferred from the stomach through the upper small intestine, after a high-calorie, high-fat meal. 2) Evaluate whether itraconazole concentrations in the colloidal phase of aqueous contents of the upper small intestine are useful for the assessment of dose effects in the fed state and food effects on plasma levels. METHODS: Itraconazole concentrations, apparent viscosity, and solubilization capacity were measured in aspirates from the upper gastrointestinal lumen collected during a recently performed clinical study in healthy adults. Published itraconazole concentrations in plasma, after a high-calorie high-fat meal and Sporanox® ASD pellets, and in contents of the upper small intestine of healthy adults, after administration of Sporanox® ASD pellets in the fasted state, were used to achieve the second objective. RESULTS: When Sporanox® ASD pellets (up to 200 mg) are transferred from the stomach through the upper small intestine, after a high-calorie, high-fat meal, itraconazole concentrations in the colloidal phase or the micellar phase of aqueous contents of the upper small intestine are unsaturated, in most cases. During the first 3 h post-dosing after a high-calorie, high-fat meal, the impact of dose (200 mg vs. 100 mg) on itraconazole concentrations in the colloidal phase of aqueous contents of the upper small intestine seems to underestimate the impact of dose on plasma levels. When Sporanox® ASD pellets are administered after a high-calorie, high-fat meal at the 200 mg dose level, itraconazole concentrations in the colloidal phase of aqueous contents of the upper small intestine are, on average, lower than those achieved in fasted state. CONCLUSIONS: When Sporanox® ASD pellets are transferred from the stomach to the upper small intestine after a high-calorie, high-fat meal, itraconazole's arrival at the intestinal epithelium seems to be limited by its arrival at the colloidal phase of aqueous contents of the upper small intestine. The impact of dose (100 mg vs. 200 mg) on plasma levels after a high-calorie, high-fat meal and during the gastrointestinal transfer of Sporanox® pellets requires consideration of pre-systemic itraconazole metabolism. At the 200 mg dose level, after taking into consideration differences in the volume of the contents of the upper small intestine between the fasted and the fed state during the gastrointestinal transfer of Sporanox® ASD pellets, itraconazole concentrations in the colloidal phase of aqueous contents of the upper small intestine suggest a mild negative food effect on average plasma levels; published clinical data are inconclusive.

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In order to obtain high yield pomelo peel pectin with better physicochemical properties, four pectin extraction methods, including hot acid extraction (HAE), microwave-assisted extraction (MAE), ultrasound-assisted extraction, and enzymatic assisted extraction (EAE) were compared. MAE led to the highest pectin yield (20.43%), and the lowest pectin recovery was found for EAE (11.94%). The physicochemical properties of pomelo peel pectin obtained by different methods were also significantly different. Pectin samples obtained by MAE had the highest methoxyl content (8.35%), galacturonic acid content (71.36%), and showed a higher apparent viscosity, thermal and emulsion stability. The pectin extracted by EAE showed the highest total phenolic content (12.86%) and lowest particle size (843.69 nm), showing higher DPPH and ABTS scavenging activities than other extract methods. The pectin extracted by HAE had the highest particle size (966.12 nm) and degree of esterification (55.67%). However, Fourier-transform infrared spectroscopy showed that no significant difference occurred among the different methods in the chemical structure of the extracted pectin. This study provides a theoretical basis for the industrial production of pomelo peel pectin.

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This research aimed to analyze the impacts of sonication on the rheological properties and color indexes of aqueous solutions of Basil seed gum (BSG), Lallemantia seed gum (LSG), and Wild sage seed gum (WSG). The apparent viscosity (AV) of aqueous solutions of gums decreased with increasing shear rate (SR) from 12.2 s-1 to 134.5 s-1. Also, the AV (at SR = 61 s-1) of BSG, LSG, and WSG solutions reduced from 0.015 to 0.006 Pa.s, 0.023 to 0.010 Pa.s, and 0.009 to 0.004 Pa.s with enhancing the sonication time from 0 to 20 min, respectively. Various rheological equations were employed to fit the empirical values, and the findings confirmed that the Power law (PL) model was the best fit to explain the flow behaviour of these gums solutions. The consistency coefficient (k-index) of BSG, LSG, and WSG solutions significantly (p < 0.05) reduced from 0.108 to 0.017 Pa.sn, 0.143 to 0.033 Pa.sn, and 0.034 to 0.014 Pa.sn with increasing sonication time from 0 to 20 min, respectively. The flow behaviour index (n-index) of the gums solutions increased with increasing sonication time. By applying ultrasound, the lightness (L⁎) and blueness/yellowness (b⁎) indexes of the solutions were increased, and the greenness/redness (a⁎) index was reduced.

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Today sonication process is used as a new green tool with unique impacts on foods preservation and processing. Ultrasonic modification is an appropriate strategy to obtain good gums with useful physicochemical characteristics and molecular structure. This research aimed to analyze the impacts of sonication at different intensities (0, 75, and 150 W) and time (0, 5, 10, 15, and 20 min) on the viscosity and rheological characteristics of carboxymethyl cellulose (CMC) solution. The results confirmed that the apparent viscosity of CMC solution reduced from 0.030 to 0.021 Pa.s with increasing shear-rate from 12.2 s-1 to 134.5 s-1 (75 W for 10 min). Also, the apparent viscosity of CMC solution reduced from 0.028 to 0.019 Pa.s with enhancing the sonication time from 0 to 20 min (shear-rate = 61 s-1, 150 W). Various rheological equations were employed to fit the empirical values, and the results confirmed that the Power law model was the best fit to explain the flow behaviour of CMC solution. The consistency coefficient of CMC solution significantly reduced from 0.065 Pa.sn to 0.032 Pa.sn (p < 0.05) with enhancing sonication time from 0 to 20 min (75 W). Furthermore, the consistency coefficient of CMC solution decreased significantly (p < 0.05) while the ultrasonic power enhanced. Flow behaviour index of CMC solution enhanced significantly (p < 0.05) while the intensity and time of sonication enhanced.

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Performance evaluation of drilling fluids is essential for a successful drilling project, as they not only remove drill cuttings but also prevent undesired penetration or outflow of formation fluids by sealing off wellbore walls. However, concerns have been raised about the use of chemical additives in drilling fluids due to their toxicity and non-biodegradability. To this end, agricultural waste materials are recognized as a promising alternative as they are cost-effective, environmentally sustainable, and can be used as a substitute for lost circulation materials. Rice husk ash (RHA) has become popular as an additive due to its renewable characteristics, including its large surface area, silica content, and microporous structure. This research article explores the rheological properties of drilling fluid with RHA as a filter control medium. The results showed that increasing concentrations of RHA in the drilling mud significantly improved its rheology, particularly at higher concentrations (15 and 20 wt.%). The addition of RHA modified the filtration and rheological properties of the drilling mud, resulting in improved plastic viscosity, yield point, density, gel strength, and thixotropy. However, filter loss and mud cake thickness increased at elevated RHA concentrations. Furthermore, the pH test revealed that the mud's properties shifted toward the acidic region as the RHA concentration increased. The results indicate that RHA could be used as a sustainable and cost-effective alternative to conventional chemical additives with a positive environmental impact. This study may also provide valuable insights into the use of RHA in water-based bentonite mud and could serve as a guide for future research in the drilling industry.

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In the present paper, we investigate how the reductions in shear stresses and pressure losses in microfluidic gaps are directly linked to the local characteristics of cell-free layers (CFLs) at channel Reynolds numbers relevant to ventricular assist device (VAD) applications. For this, detailed studies of local particle distributions of a particulate blood analog fluid are combined with wall shear stress and pressure loss measurements in two complementary set-ups with identical flow geometry, bulk Reynolds numbers and particle Reynolds numbers. For all investigated particle volume fractions of up to 5%, reductions in the stress and pressure loss were measured in comparison to a flow of an equivalent homogeneous fluid (without particles). We could explain this due to the formation of a CFL ranging from 10 to 20 µm. Variations in the channel Reynolds number between Re = 50 and 150 did not lead to measurable changes in CFL heights or stress reductions for all investigated particle volume fractions. These measurements were used to describe the complete chain of how CFL formation leads to a stress reduction, which reduces the apparent viscosity of the suspension and results in the Fåhræus-Lindqvist effect. This chain of causes was investigated for the first time for flows with high Reynolds numbers (Re∼100), representing a flow regime which can be found in the narrow gaps of a VAD.

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Chloroplasts are abundant organelles in a diverse range of plant materials; they are predominantly composed of multicomponent thylakoid membranes which are lipid and protein rich. Intact or unravelled thylakoid membranes should, in principle, have interfacial activity, but little has been published on their activity in oil-in-water systems, and nothing on their performance on an oil continuous system. In this work different physical methods were used to produce a range of chloroplast/thylakoid suspensions with varying degrees of membrane integrity. Transmission electron microscopy revealed that pressure homogenisation led to the greatest extent of membrane and organelle disruption compared to less energy intensive preparation methods The ability of the derived materials to modulate the flow behaviour of a chocolate model system (65% (w/w) sugar/ sunflower oil (natural amphiphiles removed) suspension) was investigated by acquiring rheological parameters. All chloroplast/thylakoid preparations reduced yield stress, apparent viscosity, tangent flow point and cross over point in a concentration-dependent fashion, although not as significantly as polyglycerol polyricinoleate applied at a commercially relevant concentration in the same chocolate model system. Confocal laser scanning microscopy confirmed presence of the alternative flow enhancer material at the sugar surfaces. This research reveals that low-energy processing methods that do not extensively disrupt thylakoid membranes are applicable to generating materials with marked capacity to affect the flow behaviour of a chocolate model system. In conclusion, chloroplast/thylakoid materials hold strong potential as natural alternatives to synthetic rheology modifiers for lipid-based systems such as PGPR.

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As a matrix for melt-cast explosives, 3,4-dinitropyrazole (DNP) is a promising alternative to 2,4,6-trinitrotoluene (TNT). However, the viscosity of molten DNP is considerably greater compared with that of TNT, thus, requiring the viscosity of DNP-based melt-cast explosive suspensions to be minimized. In this paper, the apparent viscosity of a DNP/HMX (cyclotetramethylenetetranitramine) melt-cast explosive suspension is measured using a Haake Mars III rheometer. Both bimodal and trimodal particle-size distributions are used to minimize the viscosity of this explosive suspension. First, the optimal diameter ratio and mass ratio (two crucial process parameters) between coarse and fine particles are obtained from the bimodal particle-size distribution. Second, based on the optimal diameter ratio and mass ratio, trimodal particle-size distributions are used to further minimize the apparent viscosity of the DNP/HMX melt-cast explosive suspension. Finally, for either the bimodal or trimodal particle-size distribution, if the original data between the apparent viscosity and solid content are normalized, the resultant plot of the relative viscosity versus reduced solid content collapses to a single curve, and the effect of the shear rate on this curve is further investigated.

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In this work, the differences in macrostructure and microstructure, rheology, and storage stability of pre-emulsified safflower oil (PSO) prepared by natural and magnetic field modified soy 11S globulin were analysised. It was concluded that the PSO with magnetic field modified soy 11S globulin (MPSO) has better emulsifying activity and physical stability. The changes in gel quality, oxidational sensitivity, rheological, and sensory properties of pork batters with different substitute ratios (0%, 25%, 50%, 75%, and 100%) of pork back-fat by MPSO with magnetic field modified soy 11S globulin were studied. Compared to the sample without MPSO, pork batter with MPSO showed higher emulsion stability, apparent viscosity, L⁎ value, springiness, cohesiveness, and expressible moisture, while lower a⁎ value and cooking loss. Moreover, added MPSO could be more uniformly distributed into the meat matrix with smaller holes. With the increase in the replacement proportion of pork back-fat, the hardness, water- and fat-holding capacity, and P21 of pork batter significantly decreased (P < 0.05). As revealed by sensory evaluation and TBARS, using MPSO to substitute for pork back-fat decreased the lipid oxidational sensitivity of pork batter, and without negative effects on the appearance, juiciness and overall acceptability. Overall, it is feasible to apply MPSO as a pork-fat replacer to produce reduced-animal fat pork batter with excellent gel and sensory properties.

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This study aimed to evaluate the effect of the pH levels (5.8, 6.0, 6.2, and 6.4) on analogue pizza cheese (APC) rheological and physical characteristics. The APC formulation included 25% vegetable oil and 18.5% rennet casein. The APC samples were made using a Thermomix device and the cheese was stored at + 5 °C for 5 days before it was transferred to - 18 °C. Rotational rheometer measurements showed that all samples followed Herchel-Buckley viscoplastic Model with a different yield stress, highest apparent viscosity, and shear stress values were obtained at pH 6.4 followed by pH 6.2; then the values were dropped by 70%. Melting and stretching showed the best characteristics for the APC sample at pH 6.4, whereas at pH 6.0 stretching values decreased by 77%. The APC samples at pH ≥ 6.2 showed better stability after 6 months of frozen storage in the apparent viscosity than other cheeses. This study concluded that better rheological and physical properties were obtained for the APC at pH ≥ 6.20 and that significant variation for the rheological behavior of the APC can be based on the pH alone, as a slight alteration in the pH was found to affect product quality and acceptability.

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The optimization of downstream processing is a critical step in any microalgae-related process. The microalgal biomass is separated from the initial diluted cultures to form a concentrated slurry, the properties of which greatly influence the design and performance of further processing steps, such as enzymatic hydrolysis. In this work, the rheological behaviour of two microalgal concentrates produced both in freshwater (Scenedesmus almeriensis) and seawater (Nannochloropsis gaditana) were studied. Measurements were performed on the entire range of biomass concentrations, from 0.5 g/L to 264 g/L. Non-Newtonian behaviour was observed whatever the water type and biomass concentration used, especially at high biomass concentrations above 10 g/L. The rheological data were adjusted to the Power Law model, and the consistency and flow behaviour indexes were correlated with the biomass concentration. The results show that the freshwater and seawater biomasses exhibited different behaviours, with freshwater slurries being more viscous than seawater ones. The high viscosity of freshwater slurries requires increased energy consumption for mixing, with an estimated cost increase of 60% when using them under the non-Newtonian conditions considered. These findings highlight the considerable effect of algal biomass rheology on the mixing power required during microalgal biomass processing.

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In this work, the rheological behavior of passion fruit peel extract was determined at different temperatures (5-40 °C) and peel content in the extract (40-55% w/w). The extract was obtained after blanching the passion fruit peels at 95 °C for 5 min, then they were crushed to reduce their size, water was added, and finally, they were subjected to liquefaction and subsequent filtration. Rheological measurements were made using a rheometer with a plate and plate geometry. Extract samples were adequately described by the power-law model exhibiting pseudoplastic behavior, without the presence of thixotropy. The temperature did not influence the flow behavior index, but the consistency coefficient did. The dynamic study (the temperature sweep test) showed that passion fruit peel extract exhibits a more elastic than viscous behavior, typical of a gel.

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The present paper focuses on evaluating the synergistic effects of dual modification with corona electric discharge (CED) and electron beam irradiation (EBI) on the rheological behavior of starch. Combined treatments were applied successively (CED/EBI and EBI/CED) and compared with single treatments. The outcomes showed that the rheological features of starch were altered by the dual modification in correlation with the irradiation dose mainly as a result of radiation-induced degradation. Decreases in apparent viscosity were described by exponential-like-models according to the order of application of the treatment sequences. The mathematical models allowed the estimation of the irradiation doses for which the viscosity decreased by e times for the dual modified starches (3.3 ± 1.3 kGy for CED/EBI and 5.6 ± 0.5 kGy for EBI/CED, respectively) and the fraction (f) of 0.47 ± 0.10 corresponding to starch granule considered to be affected by plasma. Both dual treatments yielded a synergistic effect, regardless of the order of application of the treatment sequences, being more effective in decreasing starch apparent viscosity than single EBI. However, synergism evaluation proved that the use of plasma as a pre-treatment to irradiation processing could provide benefits up to 20 kGy. These findings support the practical goals of technologists with valuable information that may facilitate or simplify the experimental design of starch dual modification with plasma and ionizing radiation.

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Micro-nano bubbles (MNBs) play important roles in the reduction of membrane fouling during membrane separation; however, such improvements are always attributed to the reduced concentration polarization on the surface of membranes and little attention has been paid on the variations of physicochemical properties of the feed caused by MNBs. In this study, the separation efficiencies of the feed containing humic acid (HA), bovine serum albumin (BSA), sodium alginate (SA) or dyes can be improved by MNBs during ultrafiltration, and the normalized fluxes can be maximally increased to 139% and 127% in the dead-end and cross-flow modes, respectively in the treatment of HA solution. We further reveal that the decreased apparent viscosity of the feed in the presence of MNBs is the key factor that enhances the normalized flux during ultrafiltration. This study gives new insight on the importance of MNBs in membrane separation and provides valuable clues for other chemical processes.

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Dysphagia patients might need to thicken drinks. The viscosity of these thickened drinks varies among commercial thickeners and drinks compromising the ingesta safety. The aim of this study was to investigate how temperature and resting time affect the rheological properties of thickened drinks. Four commercial thickeners were used to thicken water, coffee, orange juice, and milk at two concentration levels used in dysphagia drinks (nectar and pudding). To study the effect of temperature, flow curves of thickened drinks at 10°C and 50°C were obtained and to study the effect of resting time, flow curves of thickened drinks at 25°C were obtained at different times (0, 30, and 60 min). All samples displayed shear-thinning and time-dependent behavior (thixotropy or antithixotropy). The effect of temperature on viscosity values and relative thixotropic area (RTA) depended on the thickener and the drink. Overall, apparent viscosity showed higher values at 50°C than 10°C, especially in thickeners containing starch and in drinks with higher soluble solids (milk and orange juice). This was attributed to the water absorption of pregelatinized starch granules favored by temperature. Antithixotropy was mainly observed at pudding concentration for the starch-containing thickeners, and decreased with temperature. The effect of resting time on apparent viscosity and RTA depended also on the drink and thickener. Mostly, apparent viscosity values increased with resting time and antithixotropic behavior decreased. Both effects, increase in viscosity and decrease of antithixotropy with time, indicated that thickening action was being developed over the resting time.

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The present study evaluated the rheological properties of galactomannan from Sesbania cannabina. The intrinsic viscosity of galactomannan was determined to be 8.63 ± 0.06 dl/g. Moreover, the onset of galactomannan coil overlap occurred at 5.12 ± 0.13 g/L. With increasing concentration, galactomannan showed a more distinct shear-thinning behavior, which was well characterized by the Cross model. Notably, the viscosity of polysaccharide showed a negative relationship with the temperature, while the activation energy decreased with increasing polysaccharide concentration. Furthermore, at high concentrations, the galactomannan solution showed stability after heating or freezing, as well as over the wide pH range of 5.0-9.0. Dynamic viscoelasticity measurements reveal a gradual transition from viscous to elastic behavior of galactomannans with an increasing frequency. It is anticipated that S. cannabina galactomannan will find interesting applications as a natural thickener due to the comprehensive description of its rheological properties presented herein. PRACTICAL APPLICATION: The investigated S. cannabina galactomannan has shown a higher viscosity and heat stability at high concentration, as well as a good stability at the pH range of 5-9. The S. cannabina galactomannan may be employed as stabilizers in the food field.

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The pre-treatment of waste activated sludge (WAS) has become more common since it often results in improved bioconversion to methane, in both rate and extent. However, thorough insights on the possible effects and mechanisms of mild pre-treatment techniques, such as temperatures <100 °C combined with the addition of H2O2, are still limited. This study reports the effects of the addition of 5-30 mgH2O2/g TS and its interaction with thermal pre-treatment at 70 °C on methane production, using WAS as the substrate. It was found that the addition of H2O2 increased the methane production rate, coinciding with a decrease in apparent viscosity of WAS, which probably improved mass transfer under non-ideal mixing conditions. While H2O2 solubilized proteins and carbohydrates and mineralized a small fraction of the humic substances in WAS, these biochemical transformations did not suffice to explain the observed extent and rate of methane production. A decreased particle size, the presence of Fenton's reagent, and the presence of cationic polymers in the WAS were discarded as the reasons for the observed decrease in apparent viscosity. It was concluded that the pre-treatment conditions applied in the present study might be a strategy to enhance mixing conditions in full-scale anaerobic digesters.