In this paper, it was found that with the addition of sodium dodecyl sulfate (SDS, a hydrophilic surfactant) and oleic acid (OA, a lipophilic surfactant) in a solvent with a proper composition ratio, ...a stable gel could be obtained via a simple ultrasonic treatment. The synergistic gelation of OA–SDS was verified in a series of solvents with different polarities, such as white oil (WO), LB-2000, n-hexane, polyalphaolefin (PAO10), and deionized water. The Fourier transform infrared (FTIR) analysis confirms that the gelation of OA–SDS is highly related to the ion exchange reaction between them. However, the xerogel of OA–SDS gelator in deionized water and WO (OSW) exhibited remarkably different morphologies, indicating that the gelation is based on different molecular assembly processes, which is governed by the orientation of the two surfactant molecules in liquid media. Further characterizations of OSW gel presented that the synergistic effect between OA and SDS not only existed in gelation, but also in enhancing the mechanical and thermal stability of WO, and endowing the OSW gel with reliable friction reduction and antiwear performances under variable working conditions. Subsequently, the lubrication mechanism was proposed based on rheological analysis and the morphological and compositional analysis of wear surfaces. This study provides a novel idea for the molecular design of lubricating gelators with wide adaptability to solvent polarity and working conditions.
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•The synergistic effect of OA and SDS on gelation and lubrication was presented.•The OA–SDS exhibits excellent gelling capacity in solvents of different polarities.•OA–SDS gelator in water and white oil have different gelling mechanisms.•OA–SDS gelator greatly improved the tribological properties of white oil.
•Steel and polypropylene fibers show different mechanical and rheological behavior.•Addition of fibers into concretes led to a decrease in the workability.•Steel and polypropylene fibers had little ...impact on changing the tensile strength.•All the fiber reinforced samples gained higher flexural stiffness than control sample.•The polypropylene fibers would cause the electrical resistivity to increase.
The aim of the present study is to investigate the effects of using hybrid fibers on rheological, mechanical and durability properties of the high-strength self-consolidating concrete (SCC). For this purpose, two types of fibers including hooked-end steel fibers and polypropylene fibers were used. In this study, a total of eleven mixtures were used: one as a control mix, one containing 0.5% steel fibers, four containing 0.5% hybrid fibers (steel and polypropylene), one containing 1.0% steel fibers and the four containing 1.0% hybrid fibers (steel and polypropylene). For investigating the rheological properties, slump flow, J-ring and V-funnel tests were performed. Mechanical properties were studied by conducting compressive strength, splitting tensile strength, modulus of rupture and flexural toughness tests. Moreover, ultrasonic pulse velocity conducted as a non-destructive test to assess the quality and integrity of the concrete. Durability properties of this type of concrete were evaluated by electrical resistivity tests. Effects of fibers in rheological and mechanical properties have been studied and compared.
The effect of sodium alginate (AG) on the retrogradation properties of normal cornstarch (NCS) and its anti-retrogradation mechanism were investigated by determining the pasting parameters, gel ...firmness, gelatinization parameters, retrogradation enthalpy, glass transition temperature, dynamic rheological properties, interaction force, leached amylose content, swelling power, X-ray diffraction patterns and relative crystallinity, respectively. The sodium alginate-normal cornstarch (AG-NCS) blends were treated with different ratio of NCS to AG (ranging from 10:0–9.6: 0.4) and stored at 4 °C and 25 °C for 1d or 3d, respectively. The addition of AG significantly decreased the setback value, which suggested that the short-term retrogradation of NCS was inhibited. AG obviously reduced the retrogradation enthalpy, storage modulus, and relative crystallinity of NCS, which decreased with the increase in the AG concentration. The aforementioned results suggested that addition of AG could retard the retrogradation of NCS, and the retardation effect exhibited positive correlation of AG concentration. The changes in the storage modulus after the addition of NaCl and urea suggested that the hydrogen bonding might be the main force involved in the formation and stability of the AG-NCS blends. The X-ray diffraction patterns showed that the transformation of the A-type to B-type of NCS occurred after gelatinization and retrogradation.
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•Sodium alginate exhibited a retardant effect on the retrogradation of normal cornstarch.•The hydrogen bonding was the main force in the stability of AG-NCS blends.•Starch exhibits a rapid retrogradation under 4 °C than that stored at 25 °C.
Foam mobility control technique has been extensively applied to encounter unfavorable sweep efficiency during CO2 injection in heterogeneous reservoirs. Harsh reservoir conditions have encouraged a ...need of effective mobility control agent. In this study, we present a comprehensive experimental investigation utilizing a newly developed water-soluble associative polymer as additive to foam system for stability and rheology enhancement. The performance of polymer enhanced foam on residual oil displacement was also evaluated in porous media. A significant increment in foam longevity and improved foam rheological behavior were obtained with associative polymer presence. Compared to conventional polymer’s performance, the associative polymer enhanced foam could establish the higher flow resistance and better compatibility with reservoir conditions. The addition of associative polymer profoundly increased the foam apparent viscosity and gas mobility reduction factor at optimum foam quality in the absence and presence of oil. A noticeable improvement in oil recovery efficiency was also observed in the case with associative polymer by which 28% incremental oil recovery was achieved, 14% higher than that obtained from polymer-free foam injection. The utilization of associative polymer enhanced foam is considered promising for a deepers foam propagation in the formation to recover substantial amount of residual oil.
•Foam stabilization effect by associative and conventional polymers is compared.•Associative polymer significantly improves CO2-foam stability and flow resistance.•Associative PEF leads to better mobility control than polymer-free foam.•Associative PEF yields 28% incremental recovery, 14% higher than polymer-free foam.•Associative polymer-surfactant interactions are thought for governing foam strength.
To date, the role of elasticity in drug delivery remains elusive due to the inability to measure microscale mechanics and alter rheology without affecting chemistry. Herein, we describe the in vitro ...cellular uptake and in vivo tumor uptake of nanolipogels (NLGs). NLGs are composed of identical lipid bilayers encapsulating an alginate core, with tunable elasticity. The elasticity of NLGs was evaluated by atomic force microscopy, which demonstrated that they exhibit Young's moduli ranging from 45 ± 9 to 19,000 ± 5 kPa. Neoplastic and non-neoplastic cells exhibited significantly greater uptake of soft NLGs (Young's modulus <1.6 MPa) relative to their elastic counterparts (Young's modulus >13.8 MPa). In an orthotopic breast tumor model, soft NLGs accumulated significantly more in tumors, whereas elastic NLGs preferentially accumulated in the liver. Our findings demonstrate that particle elasticity directs tumor accumulation, suggesting that it may be a design parameter to enhance tumor delivery efficiency.
Soft particulate gels are composed of a small amount of particulate matter dispersed in a continuous fluid phase. The solid components assemble to form a porous matrix, providing rigidity and control ...of the mechanical response, despite being the minority constituent. The rheological response and gel elasticity are direct functions of the particle volume fraction. However, the diverse range of different functional dependencies reported experimentally has challenged efforts to identify general scaling laws. Here we reveal a hidden hierarchical organization of fractal elements that controls the viscoelastic spectrum, and which is associated with the spatial heterogeneity of the solid matrix topology. The fractal elements form the foundations of a viscoelastic master curve, constructed using large-scale three-dimensional (3D) microscopic simulations of model gels, which can be described by a recursive rheological ladder model over a range of particle volume fractions and gelation rates. The hierarchy of the fractal elements provides the missing general framework required to predict the gel elasticity and the linear viscoelastic response of these complex materials.Colloidal gels consist of particles embedded in a fluid. It is now found that a gel’s viscoelastic spectrum, relating mechanical properties and deformation frequencies, can be understood by modelling these gels as networks of fractal viscoelastic units, connected hierarchically.
Starch nanoparticles (SNPs) were produced from pulse (faba bean and field pea) and cereal (corn and wheat) starches by rapid nanoprecipitation under identical conditions. SNP morphological features ...such as shape and particle size distribution (PSD) were determined by field emission scanning electron microscopy (FE-SEM) and dynamic light scattering (DLS) techniques. Static and dynamic rheological properties of the aqueous SNP suspensions were investigated by rotational and oscillatory rheometry. The SNPs from all starch sources were spherical in shape but varied in their size distribution. The viscosity and viscoelastic behavior of SNP suspensions when determined as a function of shear, frequency and temperature were dependent on starch source and SNP concentration. The SNP suspensions exhibited a viscous liquid-like behavior at low concentrations (i.e., 1% w/v), but an elastic gel-like behavior at high concentrations (i.e., 5% w/v). Interestingly, at a concentration of 5% (w/v), SNP suspensions showed an excellent flow behavior, demonstrating their capacity to instantaneously recover from the applied shear deformation. However, pulse SNPs displayed relatively greater viscosities and a more elastic behavior than cereal SNPs, indicating their potential to form extensive inter-particulate associations. A schematic diagram has been proposed to explain the observed rheological behaviors, predicting inter-particulate network formation at room temperature and the biphasic molecular network formation during heating of aqueous SNP suspensions. A careful selection of starch type and processing conditions, such as temperature and shear conditions, is required to achieve specific desired functionalities for SNP in the food industry.
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•Starch nanoparticles were produced from pulse and cereal starches.•The starch nanoparticles show improved shear tolerance compared to native starch.•The starch nanoparticles suspensions were liquid-like at 1% and gel-like at 5%.•Pulse starch nanoparticles exhibited greater thermal stability.•A schematic model was established to illustrate the network of starch nanoparticles.
Emulsion gels were prepared by addition of whey protein isolate (WPI) to gliadin nanoparticles (GNP)-stabilized emulsion and controllable gel strength were achieved by altering temperature, and pH ...values and ionic concentration. The effects of temperature, pH and ionic concentration on rheological properties, droplet size distribution, ζ-potential and microstructure of these systems were characterized. The elastic modulus of WPI and GNP-stabilized emulsion gels were strongly temperature-dependent. Weak emulsion gels were formed at ambient temperature by addition of WPI to the GNP-stabilized emulsions, whereas strong gels were formed by heating above the thermal denaturation temperature of the proteins. The addition of WPI has a positive effect on improving gel strength of the emulsion gels, with the strongest gels being formed at 2% WPI. The gel strength could also be modulated by adjusting pH and ionic strength, with the strongest gels being formed near the isoelectric point of the proteins (pH 5 and 6.8) and at low ionic strengths (0–200 mM). Changes in the physicochemical properties of the emulsion gels were attributed to alterations in the structural arrangement and interactions of the nanoparticle-coated lipid droplets, which was supported by the results of electrophoresis and confocal laser scanning microscopy. These findings show that the rheological properties of GNP and WPI-stabilized emulsion gel could be easily regulated by temperature, pH or ionic strength, which may make them suitable for various applications in the food industry.
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Recent clinical evidence identified anemia to be correlated with severe complications of cardiovascular disease (CVD) such as bleeding, thromboembolic events, stroke, hypertension, arrhythmias, and ...inflammation, particularly in elderly patients. The underlying mechanisms of these complications are largely unidentified. Recent Advances: Previously, red blood cells (RBCs) were considered exclusively as transporters of oxygen and nutrients to the tissues. More recent experimental evidence indicates that RBCs are important interorgan communication systems with additional functions, including participation in control of systemic nitric oxide metabolism, redox regulation, blood rheology, and viscosity. In this article, we aim to revise and discuss the potential impact of these noncanonical functions of RBCs and their dysfunction in the cardiovascular system and in anemia.
The mechanistic links between changes of RBC functional properties and cardiovascular complications related to anemia have not been untangled so far.
To allow a better understanding of the complications associated with anemia in CVD, basic and translational science studies should be focused on identifying the role of noncanonical functions of RBCs in the cardiovascular system and on defining intrinsic and/or systemic dysfunction of RBCs in anemia and its relationship to CVD both in animal models and clinical settings. Antioxid. Redox Signal. 26, 718-742.
In this study, the effects of Mesona chinensis polysaccharide (MCP) on the pasting, thermal, rheological, and textural properties of wheat starch were investigated. Rapid viscosity analysis results ...showed that MCP protects the integrity of starch granules at low concentration in the early stage of pasting. The gelatinization temperature of wheat starch–MCP gels was markedly increased with the increase in polysaccharide concentration, whereas gelatinization enthalpy (ΔHgel) decreased. Rheological analysis showed that the starch:MCP = 8.5:1.5 system exhibited a strong thixotropic property and the highest G′ and G″ among the other systems. The same results were observed in the textural experiment, indicating the existence of strong intermolecular interactions between starch granules and MCP. These results indicated that MCP can improve the thermal stability in the early stage of pasting and enhance the rheological properties of wheat starch.
•MCP promoted the thermal property of wheat starch at the early stage of pasting.•The roles of MCP were different on apparent characters depend on the starch concentration.•Thixotropy property of wheat starch-MCP with different ratios followed in this order: 8.5:1.5 > 10.0:0 > 8.0:2.0.
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