Dilational Properties Research Articles

Effect of Divalent and Monovalent Salts on Interfacial Dilational Rheology of Sodium Dodecylbenzene Sulfonate Solutions

This study presents the equilibrium surface tension (ST), critical micelle concentration (CMC) and the dilational viscoelasticity of sodium dodecylbenzene sulfonate (SDBS)-adsorbed layers in the presence of NaCl, KCl, LiCl, CaCl2 and MgCl2 at 0.001–0.1 M salt concentration. The ST and surface dilational viscoelasticity were determined using bubble-shape analysis technique. To capture the complete profile of dilational viscoelastic properties of SDBS-adsorbed layers, experiments were conducted within a wide range of SDBS concentrations at a fixed oscillating frequency of 0.01 Hz. Salts were found to lower the ST and induce micellar formation at all concentrations. However, the addition of salts increased dilational viscoelastic modulus only at a certain range of SDBS concentration (below 0.01–0.02 mM SDBS). Above this concentration range, salts decreased dilational viscoelasticity due to the domination of the induced molecular exchange dampening the ST gradient. The dilational viscoelasticity of the salts of interest were in the order CaCl2 > MgCl2 > KCl > NaCl > LiCl. The charge density of ions was found as the corresponding factor for the higher impact of divalent ions compared to monovalent ions, while the impact of monovalent ions was assigned to the degree of matching in water affinities, and thereby the tendency for ion-pairing between SDBS head groups and monovalent ions.

Quantitative correlation between rafting microstructure and anisotropic mechanical behavior in dual-phase materials

Continuum descriptions of the microstructure in dual-phase materials are introduced by fabric tensors computed from the mean intercept length (MIL) method. The fabric tensor can be decomposed into the isotropic and deviatoric components to represent the dilatation and orientation preferred properties, respectively. Systematic numerical simulations on micromechanics models and simplified microstructures are conducted. It is confirmed that the anisotropic elastic behavior can be quantitatively predicted with the help of deviatoric components. This component can be further implemented into the constitutive model to describe the time- and load-dependent evolution of the material state variable. Anisotropy induced by morphology and anisotropic constituents is discussed. The results match well with computational experiments, showing the promising application potential of the tensorial representation method and the microstructure-based mechanical property prediction model.

Stress-strain behaviour of spontaneous combustion gangue coarse aggregate concrete under FRP tube confinement

Due to its poor mechanical properties and working performance, spontaneous combustion gangue coarse aggregate concrete (SCGAC) is currently limited to non-load-bearing structures. However, these defects can be effectively improved by fiber reinforced polymer (FRP). To capture the axial compression behaviour of FRP-confined SCGAC, a total of 32 cylinders specimens (150 mm in diameter and 300 mm in height) were tested under monotonic axial compression with replacement ratio and FRP tube thickness as test variables. Test results show that, in comparison to ordinary concrete in similar conditions, the strength of FRP-confined SCGAC decreases by 5.6%–39.8% while the ultimate compressive strain increases by 11.7%–110.8%. When SCGAC confined with FRP tube, its strength increases by 1.87–4.44 times, and the ultimate strain of each specimen increased by 6.12–16.19 times. In addition, the crack forms and dilation properties of SCGAC also show significant differences when compared with ordinary concrete. Finally, a new design-oriented model for FRP-confined SCGAC is generated within the framework of the existing models for FRP-confined ordinary concrete, with necessary modification to compensate for the effect of aggregate characteristics.

The impact of SiO2 nanoparticles on the dilational viscoelastic properties of water-nonionic surfactant-fuel interface

Surfactants in ultra-low sulfur diesel (ULSD) can improve the stability of the emulsified water droplet by forming a thin film at the water-fuel interface. Emulsified water droplets block the oil spray nozzle and break down the engine, which need to be removed. For colliding emulsified water droplets, surfactant film with high viscoelastic modulus provides an obstacle to their coalescence. Micro/nanosized-SiO2 particles were added into ULSD to interrupt the arrangement of the surfactant film. After adding with 20 nm SiO2, the interfacial tension of water-monoolein-ULSD increased from 16.0 mN/m to 21.4 mN/m, and its viscoelastic modulus decreased from 17.1 mN/m to 10.9 mN/m, a decrease of 36.3%. It proved that the addition of nanosized SiO2 into water-monoolein-ULSD system increased the interfacial tension and reduced the viscoelastic modulus of the monoolein film. However, after adding nanosized SiO2, the viscoelastic modulus of the water-PETO-B-ULSD layer had no significant changes. Therefore, we concluded that 20 nm SiO2 disturbed the dense packing of monoolein as its adsorption to surfactants and the electrostatic repulsion force between them and the hydrophobic group, resulting in a decrease in elastic modulus. However, PETO-B had a complex branched structure leading to a loose packing, which had unoccupied adsorption sites and barely affected by the intrusion of 20 nm SiO2. Therefore, this research provided a strategy to add nanosized-SiO2 into W/O emulsions containing monoolein-like surfactant to reduce its stability.

Constitutive model for gas hydrate-bearing soils considering different types of hydrate morphology and prediction of strength-band

The present study proposes a new elasto-plastic constitutive model that considers different types of hydrates in pore spaces. Many triaxial compression tests on both methane hydrate-bearing soils and carbon dioxide hydrate-bearing soils have been carried out over the last few decades. It has been revealed that methane hydrate-bearing soils and carbon dioxide hydrate-bearing soils have different strength and dilatancy properties even though they have the same hydrate contents. The reason for this might be due to the different types of hydrate morphology. In this study, therefore, the effect of the hydrate morphology on the mechanical response of gas-hydrate-bearing sediments is investigated through a model analysis by taking into account the different hardening rules corresponding to each type of hydrate morphology. In order to evaluate the capability of the proposed model, it is applied to the results of past triaxial compression tests on both methane hydrate-containing and carbon dioxide hydrate-containing sand specimens. The model is found to successfully reproduce the different stress–strain relations and dilatancy behaviors, by only giving consideration to the different morphology distributions and not changing the fitting parameters. The model is then used to predict a possible range in which the maximum deviator stress can move for various hydrate morphology ratios; the range is defined as the strength-band. The predicted curve of the maximum deviator stress obtained by the constitutive model matches the empirical equations obtained from past experiments. It supports the fact that the hydrate morphology ratio changes with the total hydrate saturation. These findings will contribute to a better understanding of the relation between the microscopic structures and macro-mechanical behaviors of gas-hydrate-bearing sediments.

PROGNOSTICATION OF COMPLICATED COURSE OF ACUTE MYOCARDIAL INFARCTION WITH CONCOMITANT TYPE 2 DIABETES MELLITUS BASED ON USE OF ENDOTHELIAL MONOCYTE ACTIVATING POLYPEPTIDE-ІІ

The aim: To determine the prognostic value of endothelial monocytic peptide ІІ in the course of AMI (acute myocardial infarction) in combination with type 2 diabetes mellitus (DM) Materials and methods: The study involved 120 patients divided in 2 groups: Group 1 – patients with acute myocardial infarction (AMI) with concomitant type 2 DM (n=69); Group 2 – patients with AMI without concomitant type 2 DM (n=51). Control group was composed with 20 almost healthy persons. Results: It was determined that in patients with AMI in combination with type 2 diabetes, the level of endothelial monocyte-activating polypeptide II (EMAP-II) was 1.65 times higher than in patients without concomitant type 2 DM (p <0.05). The patients with AMI and type 2 DM who were included in the group of the 3rd tertile according to level of EMAR-II had the complicated course compared to patients in the groups of the 1st and 2nd tertiles. Q-positive AMI was found in 100% of patients who belonged to the group of the 3rd tertile; recurrence of AMI occurred only in patients whose EMAR-II index was included in the 3rd tertile. Conclusions: According to the results of endothelial function analysis with usу ща the marker of EMAP-II endothelial dysfunction in patients with AMI and concomitant type 2 DM, the increased level of this parameter was characteristic of pronounced violation of dilatation properties of the vascular wall and of the other indicators of complicated comorbid conditions.

Shear and dilatational rheological properties of vegetable proteins at the air/water interface

Many food products are multiphase systems and their structural and textural properties are determined by the amount and the characteristics of the different ingredients making up the system. They are created by homogenization of two or more immiscible phases, to form emulsions or foams. Proteins are widely used to stabilize the interfaces of these types of system because they have high nutritional value and they are able to adsorb quickly at the interface decreasing the interfacial tension and improving the mechanical resistance. Recently, proteins extracted from vegetable seeds have been receiving much attention from the food industry, thanks to their good environmental sustainability and healthy composition, but the scientific literature is lacking in information on the surface activity and emulsifying ability of these proteins. In this work, the surface properties of three different proteins extracted from vegetable sources (soy, hemp and brown rice seeds) were investigated using interfacial shear and dilatational kinematics. Linear viscoelastic properties were evaluated using small amplitude oscillatory tests (about 10%ΔV/V and 2% for dilatational and shear deformation, respectively); in addition, stress relaxation after quick expansion/compression and shear creep were also used to obtain information about the viscoelasticity and the characteristic time of relaxation of the interfacial film. The three proteins displayed excellent interfacial properties similar among them. Brown rice protein yields stronger interfacial layers whereas soy is more liable to structure the interface and hemp exhibits intermediate properties. Obtained results demonstrate that brown rice and hemp proteins could be used to obtain food multiphase systems, like foams, without the addition of surfactants or animal proteins, thanks to their interfacial characteristics, and they can yield a high nutritional content thanks to their amino acid profile.

The axial compressive experiment and analytical model for FRP-confined gangue aggregate concrete

Coal gangue is the main industrial waste in the mining process, the best treatment is to completely replace the coarse aggregate and compound it into gangue aggregate concrete (GAC) to be used in the mining infrastructure construction. But the relatively inferior performance of GAC is the main factors limiting its application in structural components. Carbon fiber-reinforced polymer was employed as an external confinement to form a novel composite column (i.e. CFRP-confined GAC column) with optimized performance. To evaluate the mechanical behavior of the novel CFRP-confined GAC column, different inner core strength and outer CFRP jacket thickness were taken as the variables in the monotonic axial compression test. The results show that the confined GAC exhibited apparent volumetric compaction behavior and the compressive strength and ductility were greatly enhanced, but when the thickness of the CFRP jacket exceeds two layers, this improvement turned insignificant. In addition, the confinement stiffness had a more obvious effect on the dilation properties of the confined GAC compared with confined normal aggregate concrete (NAC). Furthermore, in order to provide support for the subsequent design and analysis of the confined GAC, the modified models for the dilation properties, ultimate strength and the corresponding ultimate strain of CFRP-confined GAC column were established combined with the confinement stiffness ratio and strain ratio. In addition, the incremental process of obtaining the stress–strain relationship curve was also redefined.

A Granular Thermodynamic Model to Describe the Temperature/Mechanical Characteristics of Sandy Soil

Based on the granular-solid-hydrodynamic theory, the constitutive model considering the thermo-hydro-mechanical (THM) coupled action is established, and the dilatancy property of sandy soil under coupled high mechanical pressure and temperature is simulated. The relationship between the energy dissipation and the macroscopic stress-strain changes at the grain level of saturated sandy soil is connected by defining the transfer coefficient and the energy function, without considering the concepts of yield surface and hardening parameters in classical plastic mechanics. Additionally, the changes in temperature, relative density and confining pressure during the shearing process cause particle rolling, slipping and friction. The energy dissipation in this process is described by defining the concept of particle entropy and particle temperature. In the calculation, the isotropic compression test, drained and undrained shear test of sandy soil under high stress are simulated respectively. The validity of the model is proved by comparing with the test results. Meanwhile, the stress-strain relationship and pore pressure variation law of sandy soil under different temperatures are predicted. The results show that the effect of temperature on shear strength is limited, and the pore pressure will gradually increase and become stable with the increase of temperature. Thus, this work establishes the soil THM coupled model from the perspective of micro energy dissipation, which can provide new theoretical support for the prediction of natural disasters such as landslides and debris flow.

Dilation properties of coherent Nearly-Linear models

Dilation is a puzzling phenomenon within Imprecise Probability theory: when it obtains, our uncertainty evaluation on event A is vaguer after conditioning A on B, whatever is event B in a given partition B. In this paper we investigate dilation with coherent Nearly-Linear (NL) models. These are a family of neighbourhood models, obtaining lower/upper probabilities by linear affine transformations (with barriers) of a given probability, and encompass several well-known models, such as the Pari-Mutuel Model, the ε-contamination model, the Total Variation Model, and others. We first recall results we recently obtained for conditioning NL model with the standard procedure of natural extension and separately discuss the role of the alternative regular extension. Then, we characterise dilation for coherent NL models. For their most relevant subfamily, Vertical Barrier Models (VBM), we study the coarsening property of dilation, the extent of dilation, and constriction. The results generalise existing ones established for special VBMs. As an interesting aside, we discuss in a general framework how logical (in)dependence of A from B or extreme evaluations for A influence dilation.

Triaxial behaviour of geotextile reinforced sand

ABSTRACT In order to study the behaviour of reinforced sand, a series of monotonic consolidated drained and consolidated undrained triaxial tests was conducted on Chlef sand samples and, respectively, sand samples reinforced with one layer and two layers of geotextile reinforcement. Considering both the relatives densites of samples (Dr = 30% and 80%) and the different levels of confining pressure (p’c) of 50, 100, and 200 kPa. It is noticed from the obtained results that reinforcement contribution was evident in the drained condition than for the undrained one. Results have shown under low confining pressure that adding two layers of geotextile reinforcement to loose sample leads to an increase in the value of maximum shear strength significantly for undrained sample of about 97%, then it will be less important by increasing confining pressure up to 200 kPa; at this level, the maximum shear strength has become more pronounced for the drained reinforced sample. It was also observed that the dilation of dense samples has clearly affected by the confining pressure, and this should be mainly attributed to the low dilatancy property of Chlef sand.

Effect of electrolyte on the surface dilational rheological properties of branched cationic surfactant

The studies of surface dilational rheology are important to detent the nature of adsorption film and the properties of foam. In this paper, the adsorption and dilational rheological properties of branched cationic surfactant hexadecanol polyoxyethylene(3) glycidyl ether ammonium chloride (C16G(EO)3PC) at the air-water interface in the absence and presence of electrolyte (NaCl) were investigated by drop shape analysis. The results show that the surface adsorption layer of C16G(EO)3PC behaves elastic in nature with high value up to 90 mN/m, which indicates that the slow relaxation process plays a main role because of the re-arrangement of long branched alkyl chain. The addition of NaCl will enhance diffusion-exchange process and accelerate the formation of film and decreases dilational elasticity obviously. At low NaCl concentration, the in-film slow relaxation process dominates the nature of film, dilational viscosity decreases with an increase of oscillating frequency. By adding more NaCl, diffusion-exchange process plays the crucial role and dilational viscosity increase as a function of frequency. Moreover, viscosity at high NaCl concentration shows larger value under higher oscillating frequency, indicating the contributions of fast diffusion-exchange process. The elastic adsorption film becomes to be viscoelastic by adding electrolyte.

Dilatant Properties of Random Sphere Packing

Dilatant Properties of Random Sphere Packing

The Oscillatory Spinning Drop Technique. An Innovative Method to Measure Dilational Interfacial Rheological Properties of Brine-Crude Oil Systems in the Presence of Asphaltenes

The oscillatory spinning drop method has been proven recently to be an accurate technique to measure dilational interfacial rheological properties. It is the only available equipment for measuring dilational moduli in low interfacial tension systems, as it is the case in applications dealing with surfactant-oil-water three-phase behavior like enhanced oil recovery, crude oil dehydration, or extreme microemulsion solubilization. Different systems can be studied, bubble-in-liquid, oil-in-water, microemulsion-in-water, oil-in-microemulsion, and systems with the presence of complex natural surfactants like asphaltene aggregates or particles. The technique allows studying the characteristics and properties of water/oil interfaces, particularly when the oil contains asphaltenes and when surfactants are present. In this work, we present a review of the measurements of crude oil-brine interfaces with the oscillating spinning drop technique. The review is divided into four sections. First, an introduction on the oscillating spinning drop technique, fundamental and applied concepts are presented. The three sections that follow are divided according to the complexity of the systems measured with the oscillating spinning drop, starting with simple surfactant-oil-water systems. Then the complexity increases, presenting interfacial rheology properties of crude oil-brine systems, and finally, more complex surfactant-crude oil-brine systems are reviewed. We have found that using the oscillating spinning drop method to measure interfacial rheology properties can help make precise measurements in a reasonable amount of time. This is of significance when systems with long equilibration times, e.g., asphaltene or high molecular weight surfactant-containing systems are measured, or with systems formulated with a demulsifier which is generally associated with low interfacial tension.

New Properties of the Multivariable $$H^\infty $$ Functional Calculus of Sectorial Operators

This paper is devoted to the multivariable \(H^\infty \) functional calculus associated with a finite commuting family of sectorial operators on Banach space. First we prove that if \((A_1,\ldots , A_d)\) is such a family, if \(A_k\) is R-sectorial of R-type \(\omega _k\in (0,\pi )\), \(k=1,\ldots ,d\), and if \((A_1,\ldots , A_d)\) admits a bounded \(H^\infty (\Sigma _{\theta _1}\times \cdots \times \Sigma _{\theta _d})\) joint functional calculus for some \(\theta _k\in (\omega _k,\pi )\), then it admits a bounded \(H^\infty (\Sigma _{\theta _1}\times \cdots \times \Sigma _{\theta _d})\) joint functional calculus for all \(\theta _k\in (\omega _k,\pi )\), \(k=1,\ldots ,d\). Second we introduce square functions adapted to the multivariable case and extend to this setting some of the well-known one-variable results relating the boundedness of \(H^\infty \) functional calculus to square function estimates. Third, on K-convex reflexive spaces, we establish sharp dilation properties for d-tuples \((A_1,\ldots , A_d)\) which admit a bounded \(H^\infty (\Sigma _{\theta _1}\times \cdots \times \Sigma _{\theta _d})\) joint functional calculus for some \(\theta _k<\frac{\pi }{2}\).

A bactericide peptide changing the static and dilatational surface elasticity properties of zwitterionic lipids at the air-water interface: Relationship with the thermodynamic, structural and morphological properties

In this paper, we studied how different hydrophilicity degrees of the polar groups of the lipids dipalmitoylphosphatidylcholine (DPPC) and dipalmitoyl phosphatidylethanolamine (DPPE) influence the interaction of the antibiotic peptide vancomycin (VC), affecting the physicochemical properties of the monolayers, including thermodynamic, rheological, structural and morphological ones. Lipid Langmuir monolayers were prepared at air-water interfaces with VC aqueous solution as subphase and characterized with tensiometry, Brewster angle microscopy, infrared spectroscopy, dilatational, and interfacial shear rheology. The presence of PC or PE groups as polar head groups of the phospholipid monolayers modulated the interaction of VC adsorbing from the aqueous subphase since for DPPC, vancomycin condenses the monolayer, making it less stable, fluid, and more disordered. In contrast, for DPPE, vancomycin expands the monolayer, making it more stable, keeping the compressibility, and leading to the formation of interfacial aggregates, which are not observed for DPPC. We concluded thatelectrostatic interactions induced the insertion of the peptide into the polar heads of the monolayers (DPPE), while hydrophobic interactions, in addition to ion-dipole interactions, induced the adsorption of the peptide onto the polar head of the monolayers (DPPC).

Foam Structure Preservation during Microwave-Assisted Vacuum Drying: Significance of Interfacial and Dielectric Properties of the Bulk Phase of Foams from Polysorbate 80-Maltodextrin Dispersions.

This study aimed at examining the cause of differences in the structure preservation of polysorbate 80–maltodextrin foams during microwave-assisted vacuum drying (MWVD) versus conventional vacuum drying (CVD). Aqueous dispersions of 3% polysorbate 80 and 0–40% maltodextrin were characterized for their dielectric and interfacial properties, and results were related to their drying performance in a foamed state. Surface tension and surface dilatational properties as well as dielectric properties clearly responded to the variation in the maltodextrin content. Likewise, the foam structure preservation during CVD was linked to the maltodextrin concentration. Regarding MWVD, however, foams collapsed at all conditions tested. Nevertheless, if the structure during MWVD remained stable, the drying time was significantly reduced. Eventually, this finding could be linked to the dielectric properties of polysorbate 80 rather than its adsorption kinetics and surface film viscoelasticity as its resonant frequency fell within the working frequency of the microwave drying plant.

Influence of interfacial characteristics and dielectric properties on foam structure preservation during microwave-assisted vacuum drying of whey protein isolate-maltodextrin dispersions

This study aimed at assessing the correlation between interfacial and dielectric properties of whey protein isolate (WPI)-maltodextrin (MD) dispersions and their foam structure stability during conventional vacuum drying (CVD) and microwave-assisted vacuum drying (MWVD). Interestingly, the presence of MD clearly increased the surface activity of WPI, whereas the surface dilatational properties were rather unaffected. Besides, loss factor and resonant frequency linearly increased with MD concentration, while the dielectric constant decreased. Regarding drying, foam structure preservation during CVD was mainly correlated with the dilatational elasticity. Thereby, all samples remained stable throughout the drying process. Compared to CVD, MWVD required ≥20% MD to avoid foam collapse. In addition, MWVD-dried samples exhibited larger bubble sizes, which was linked to the volumetric heating and higher mechanical stress as compared to CVD. Overall, high surface dilatational elasticity and bulk viscosity were identified as key parameters to ensure foam structure preservation during vacuum drying. • Maltodextrin content ≥30% affects interfacial properties of WPI. • Dielectric properties of WPI depend on maltodextrin content and temperature. • Foam decay is related to interfacial properties. • Foam structure stability during MWVD is linked to surface elasticity.

Adsorption kinetics and dilatational rheological properties of recombinant Pea Albumin-2 at the oil-water interface

To investigate the adsorption kinetics and dilatational rheological properties of Pea Albumin-2 (PA-2) at the oil-water interface, recombinant PA-2 was expressed and purified. Our native-PAGE, SDS-PAGE, and homology modeling results indicated that PA-2, a kind of globular protein, could form dimers by non-covalent interactions rather than disulfide bonds. The TEM results showed that some PA-2 proteins could form aggregates with the size of around 2–3 μm. Unlike other globular proteins, PA-2 exhibited the non-monotonic kinetic dependency of the dynamic viscoelastic modulus (E). Besides, the rate of rearrangement (kR) of PA-2 was significantly higher than that of other typical food proteins. Our results demonstrated that PA-2 could adsorb to the oil-water interface in the form of aggregates. The addition of 2-ME (β-mercaptoethanol) would impact dilatational rheological properties of PA-2, leading to disaggregation and higher rearrangement of PA-2 protein aggregates at the oil-water interface. Our data offered more information on the interfacial dynamic properties of globular proteins, and provided a new insight to the conformational changes of globular proteins at the oil-water interface, basing on their dynamic viscoelastic behaviors.

Adsorption and viscoelastic properties of chitosan lactate at the liquid-gas interface

The surface tension and dilational rheological properties (viscoelasticity modulus and phase angle) of chitosan lactate solutions at the liquid-gas interface are investigated by the oscillating drop shape method. The results were analyzed using the adsorption model proposed earlier for proteins in the framework of non-ideal two-dimensional solution theory. It was found that the experimental values of equilibrium surface tension of chitosan lactate solutions are in good agreement with this model. The results of the dynamic surface tension and adsorption kinetics analysis showed that chitosan lactate is characterized by a non-diffusion (barrier) adsorption mechanism. This fact determines the qualitative predictive value of the applied theoretical model to describe the extreme behavior of the dependence of the viscoelasticity modulus on the surface pressure.