Interfacial Patterns Research Articles

Austenite-martensite interfacial patterns and energy dissipation of phase transformation in Ni-Mn-Ga single crystal

The martensitic phase transformation occurs in Shape Memory Alloys (SMA) via the nucleation/propagation of the Austenite-Martensite interface (A-M interface), which is a transition region (domain) between the two coexisting phases. For providing compatibility, the transition region consists of various martensitic twin structures (laminates), forming different interfacial patterns, such as parallel laminates and branching laminates. Due to the energy accumulation in the interfacial structures (e.g., elastic mismatch and twin-boundary surface energy), the interfacial patterns should be relevant to the driving force (energy dissipation) and the associated kinetics of the phase transformation. In this paper, we adopt a special thermal loading, small-temperature-gradient “heating-cooling-reheating”, to control the A-M interface's forward and reverse propagation to generate different interfacial patterns in a Ni-Mn-Ga single crystal SMA with the observation on the twin structures (by optical microscope and SEM) and the InfraRed measurement on the temperature hysteresis of the interface propagation (for characterizing the thermal driving force). Simple energetic analysis indicates that the thermal driving force (energy dissipation) is directly related to the stored energy in the interfacial structure, particularly the large mismatch elastic energy near the habit plane. This study not only provides the details of the various interfacial patterns and their dependence on the loading path, but also indicates the driving force and the associated mechanism about the pattern evolution to understand the phase transformation process.

Coating flow of a liquid film with colloidal particles on a vertical fiber

A thin liquid film of colloidal suspension is considered which is spreading down on a vertical cylinder under the effect of gravity. A precursor film model is employed at the three-phase contact line to relieve the stress singularity. The curvature pressure leads to the formation of a capillary ridge at the contact-line. Bulk and surface colloids are assumed to be present in the liquid film. The interfacial pattern is governed by the film evolution equation, obtained by simplifying mass and momentum balance equations within the lubrication assumption, while rapid vertical diffusion is assumed for the advection–diffusion equation of the bulk concentration. Fluid viscosity and diffusivity are considered to be functions of the particle volume fraction. The effects of the bulk and surface colloids on the spreading film dynamics are systematically studied. The presence of bulk colloids leads to the thinning of the capillary ridge for smaller inlet bulk colloid concentrations. On the other hand, a larger inlet bulk concentration leads to the formation of a secondary advancing front behind the capillary ridge in the film profile. A reduced contact point velocity is observed with an increase in the upstream bulk concentration. Surface concentration is found to result in a hump-like structure behind the capillary ridge in the upstream direction due to solutal Marangoni stress. The Marangoni stress also hinders the surface-tension-driven spreading, resulting in a smaller contact line velocity. Reducing the Bond number results in unstable film profiles, which lead to a wave-like structure in the region with no bulk concentration gradients.

Spontaneous Imbibition in Dual Permeable Media Using Dynamic Pore Network Model

AbstractUnderstanding preferential flow in porous media holds substantial theoretical significance on the design and optimization of hydrocarbon exploitation in shale reservoir. Previous researches discussed the competition of imbibition front in layered porous media while the underlining mechanism for interfacial dynamics and induced displacement efficiency of multiphase flow remains ambiguous. In this paper, we investigate the spontaneous imbibition in dual permeable media and analyze the flux exchange between the neighboring porous zones with permeability contrast using dynamic pore network model. The impact of fluid viscosity ratio and permeability contrast on the spontaneous imbibition preference have been addressed, and finally a phase diagram for displacement efficiency has been obtained. The results reveal that the dual permeable structure enhances the invasion rate of wetting fluid in the low‐permeable zone and induces unstable displacement patterns, leading to reduction of the long‐term displacement efficiency. The interfacial pattern transition from stable displacement to unstable pattern in dual permeable media could be ascribed into the flux exchange between dual permeable zones, which shows a contrary impact on the fluid flow within the low‐permeable zone under favorable and unfavorable viscosity ratios. The permeability contrast in dual permeable media intensifies this impact during spontaneous imbibition. These results help us to understand the occurrence and mutual interaction of multiphase flow in layered porous media, and provide a theoretical guidance for the hydrocarbon exploitation in shale reservoir.

Impact of mutations in SARS-CoV-2 recombinant sub-variant XBB.1.16 on the binding affinity with human ACE2 receptor

Despite the waning threat of the COVID-19 pandemic, its detrimental impact on global health persists. Regardless of natural immunity or immunity obtained through vaccination, emerging variants of the virus continue to undergo mutations and propagate globally. The persistent mutations in SARS-CoV-2, along with the subsequent formation of recombinant sub-variants has become a challenge for researchers and health professionals, raising concerns about the efficacy of current vaccines. Gaining a better understanding of the biochemical interactions between the Spike Protein (RBD) of SARS-CoV-2 variants and the human ACE2 receptor can prove to be beneficial in designing and developing antiviral therapeutics that are equally effective against all strains and emerging variants. Our objective in this study was to investigate the interfacial binding pattern of the SARS-CoV-2 RBD-ACE2 complex of the Wild Type (WT), Omicron, and the Omicron recombinant sub-variant XBB.1.16. We aimed to examine the atomic level factors and observe how mutations influence the interaction between the virus and its host using Molecular Dynamics simulation, MM/GBSA energy calculations, and Principal Component Analysis. Our findings reveal a higher degree of structural deviation and flexibility in XBB.1.16 compared to WT and Omicron. PCA indicated a wider cluster and significant flexibility in the movements of XBB.1.16 which can also be observed in free energy landscapes, while the normal mode analysis revealed converging motions within the RBD-ACE2 complexes which can facilitate the interaction between them. A pattern of decreased binding affinity was observed in case of XBB.1.16 when compared to the WT and Omicron. These observed deviations in XBB.1.16 when compared to its parent lineage Omicron, and WT can be attributed to the mutations specific to it. Collectively, these results enhance our understanding of the impact of mutations on the interaction between this strain and the host, taking us one step closer to designing effective antiviral therapeutics against the continually mutating strains.

An Investigation of the Behaviors and Characteristics of the Interfacial Bonding Capacity between Cement Emulsified Asphalt Composite Binder and Reclaimed Asphalt Pavement

The interfacial bonding capacity between cement emulsified asphalt composite binder (CEACB) and reclaimed asphalt pavement (RAP) plays a critical role in improving the pavement performance of cold recycled asphalt emulsion mixtures (CRAEMs). This study aims to investigate the formation and development of the interfacial bonding capacity between CEACB and RAP. First, the dynamic wettability and the spreading behaviors of CEACB on RAP surfaces were explored according to the surface free energy theory. Second, digital image processing (DIP) technology was employed to recognize interfacial failure patterns. Lastly, the influence of internal and external factors on the interfacial bonding capacity between CEACB and RAP during the curing process was analyzed via grey relational analysis (GRA). The results indicate that a moderate cement content with a mass ratio of asphalt to cement equivalent to 1.0 can significantly enhance the wettability of CEACB on RAP surfaces. By appropriately prolonging the curing time and controlling the curing temperature, it is possible to increase the bonding strength between CEACB and RAP. Additionally, a strong correlation exists between initial wettability and ultimate bonding capacity during the bonding strength curing process. The good wettability that developed in the initial stage of interfacial strength formation relates to the decreased spalling rate of CEACB on the RAP surface. This study is not only devoted to understanding the mechanisms that can enhance CRAEM performance but also provides important guidance for practical engineering applications of cold recycled asphalt pavements.

Magnetic field-induced interfacial pattern formation in thin ferrofluid drops

Magnetic field-induced interfacial pattern formation in thin ferrofluid drops

Does particle size matter for soy protein nanoparticles in the fabrication and lipolysis of pickering-like emulsions?

Enzyme-mediated nanostructures have gained increasing interests and shown promising applications in functional delivery for food and pharmaceuticals. In our previous study, we fabricated three types of spherical soy protein nanoparticles (SPNP) by flavorzyme to different degree of hydrolysis (DH, 3%, 7% and 11%). These SPNPs exhibited similar subunit composition, secondary structure and surface properties, but differ in size, which is 89 nm, 106 nm and 151 nm, respectively. This study further applied them in emulsion systems for functional delivery. We systematically studied the emulsifying activities, interfacial properties including wettability, interfacial packing pattern, interfacial adsorption and dilatational rheological behavior of SPNPs, and their performance in modulating lipolysis of the emulsions under the influence of lipase, bile salts, pepsin and trypsin. All SPNPs behaved as Pickering-like stabilizers with moderate wettability at oil-water interface with three phase contact angle of 92–101°, and the SPNP with the smallest size has better emulsifying activities (D3,2 = 3.22 ± 0.00 μm in SDS solution) than native soy protein isolate (SPI) (D3,2 = 4.04 ± 0.03 μm in SDS solution). These SPNPs formed similar viscoelastic oil-water interfaces (Ed' = 20.2–21.5 mN/m), which were more glassy-like with weak in-plane interactions compared to SPI (Ed' = 28.6 ± 0.5 mN/m). All SPNPs can delay lipolysis of emulsions by lowering the access/replacement of lipase and bile salts and depressing the proteolysis by trypsin at interface in similar ways. Our work elucidated the role of particle size of enzyme-mediated plant protein-based particle in emulsion stabilization and lipolysis control, and is expected to give the theoretical support for the design of functional food emulsions with controllable energy intake.

Varying interfacial reaction patterns in (VNbTaMoW)C ceramic joints brazed with Ti-Zr-Ni-Cu filler alloy

The brazing of (VNbTaMoW)C ceramic with TiZrNiCu active filler is systematically studied. The metallurgical connection relies on two temperature-dependent patterns of interfacial reactions. At a low brazing temperature of 900°C, active Zr dominates interfacial reactions by seizing C atoms in HETMC lattice, generating a continuous (Zr, Ti, Nb)C layer and leading to the transformation of HETMC into a non-stoichiometric HETMC'. The continuous reaction layer is the weak area of joints, resulting in a shear strength of only 83 MPa. The interfacial reaction pattern becomes dominated by active Ti as the brazing temperature is increased. The continuous (Zr, Ti, Nb)C layer is transformed into a flocculent (Zr, Ti, Nb)C′ and partial HETMC' is decomposed into high-entropy intermetallic and (Ti, Nb, Ta, Zr)C particles. The improved interfacial structure enhanced the load-bearing capacity of joints, enabling the joint obtained at 980°C for 10 min to deliver the highest shear strength of 193 MPa.

Computational study of a thin film flow over a topographical feature using phase-field lattice Boltzmann method

The study employs the phase-field lattice Boltzmann method (PFLBM) to explore the dynamics of a thin film flowing over a topographical feature such as a mound or a trench. The mesoscopic nature of PFLBM makes it a suitable technique for problems involving tracking the evolution of a liquid–air interface. PFLBM simulation results are validated with experimental and analytical results confirming the viability of the numerical approach for such problems. The effect of changing the topographical height, aspect ratio, viscosity ratio, and presence of multiple mounds on the film profiles are systematically analyzed. It is observed that a steady-state solution could not be obtained for large height topographical features. The transition from a steady-state interfacial pattern to an unsteady-steady state is found to depend on the width of the topography. Geometry-based condition is employed to deal with the contact points present in the film dynamics beyond rupture. For large contact angles, the unsteady cases result in film rupture and form a continuous array of droplets of equivalent dimensions at a periodic interval. Increasing the aspect ratio reduces the width of the capillary ridge formed above the topographical feature, while the viscosity ratio reduces the maximum height of the ridge. The shapes of the capillary ridges formed over multiple mounds in the flow direction are independent if the separation between the successive mounds is beyond a critical value. This critical value strongly depends on the capillary number and is independent of the dimensions of the mound.

Interfacial instabilities in confined displacements involving non-Newtonian fluids

The growth of interfacial instabilities during fluid displacements can be driven by gradients in pressure, viscosity and surface tension, and by applying external fields. Since displacements of non-Newtonian fluids such as polymer solutions, colloidal and granular slurries are ubiquitous in natural and industrial processes, understanding the growth mechanisms and fully developed morphologies of interfacial patterns involving non-Newtonian fluids is extremely important. In this perspective, we focus on displacement experiments, wherein competitions between capillary, viscous, elastic and frictional forces drive the onset and growth of primarily viscous fingering instabilities in confined geometries. We conclude by highlighting several exciting open problems in this research area.

Autothermotaxis of volatile drops

When a drop of a volatile liquid is deposited on a uniformly heated wettable, thermally conducting substrate, one expects to see it spread into a thin film and evaporate. Contrary to this intuition, due to thermal Marangoni contraction, the deposited drop contracts into a spherical-cap-shaped puddle, with a finite apparent contact angle. Strikingly, this contracted droplet, above a threshold temperature, well below the boiling point of the liquid, starts to spontaneously move on the substrate in an apparently erratic way. We describe and quantify this self-propulsion of the volatile drop. It arises due to spontaneous symmetry breaking of thermal Marangoni convection, which is induced by the nonuniform evaporation of the droplet. Using infrared imaging, we reveal the characteristic interfacial flow patterns associated with Marangoni convection in the evaporating drop. A scaling relation describes the correlation between the moving velocity of the drop and the apparent contact angle, both of which increase with the substrate temperature. Published by the American Physical Society 2024

Incorporating soy protein hydrolysate and temperature-induced gelling polysaccharide as partial egg replacements for enhanced texture in sponge cake

This study investigated the influence of hydroxypropyl methylcelluloses (HPMCs), temperature-induced gelling polysaccharides, on the air-water interfacial properties and foaming properties of four soy proteins. Two HPMCs with different relative molecular masses (F50, lower; K4M, higher) were combined with soy protein isolate (SPI), 7S fraction (7S), selective hydrolysate by pepsin (SPSH), and limited hydrolysate by papain (SPLH). Interfacial shear rheology results showed that SPSH exhibited the highest G′ value, indicating a multi-layer adsorption structure formed due to both 7S and low molecule peptides in SPSH. Adding F50 to SPI, 7S, and SPSH improved foam expansion and stability while adding K4M negatively impacted the foam expansion of SPI, 7S, and SPSH but enhanced the foam expansion of SPLH. These findings suggest that the interfacial interaction patterns between HPMCs and soy proteins are significantly influenced by the molecular weight of HPMCs and the structure of the protein. Incorporating F50 into SPSH decreased the gelation temperature, shortened the formation time of a solid-like layer at the air-water interface, and expanded the linear viscoelastic region during structural fraction testing. Consequently, the combination of F50 and SPSH was chosen as the viable alternative to egg protein in sponge cake, as it facilitated rapid foam stability and prevented collapse during baking. The resulting sponge cake, with half of the egg replaced by the SPSH/F50 mix, exhibited a similar appearance and texture to that with only the egg added. Thus, combining temperature-induced gelling polysaccharides with SPSH offers a promising alternative to egg protein in aerated bakery food production.

Quantitative Evaluation of Interfacial Defect Size and Pattern by Solving a 3D Inverse Problem Based on Step Heating Thermography

Quantitative Evaluation of Interfacial Defect Size and Pattern by Solving a 3D Inverse Problem Based on Step Heating Thermography

1T-WS2/NCN photocatalyst with unique trion behavior and cyano-defects: Photocatalytic hydrogen evolution and mechanistic insights

The interfacial catalytic reaction rate determines the hydrogen production performance of the photocatalyst. In this work, high specific surface area and cyano-defects g-C3N4 with 1T-WS2 as a co-catalyst was prepared to construct 1T-WS2/NCN photocatalytic system. The two-electron interfacial catalytic reaction pattern formed due to the unique trions behaviour of 1T-WS2 greatly enhanced the interfacial catalytic reaction rate. Under 180 min of light, the hydrogen production of the photocatalytic system could reach 5769.3 μmol/g, which was 91.6 times that of the pristine g-C3N4. It was found that the excellent electrical conductivity of 1T-WS2 with metallic nature and the low Gibbs free energy of its active edge facilitated the hydrogen production and release. Meanwhile, the unique trions behaviour of the two-electron catalytic reaction formed in 1T-WS2 is a significant factor in increasing the rate of photocatalytic hydrogen production. And the cyano-defects in g-C3N4 acts as an electron trap, which drives charge space separation and provides sufficient electrons for trions formation, facilitating two-electron catalytic hydrogen production. This study provides a new idea for the development of electron-hole separation to improve the photocatalytic hydrogen production activity, which has important theoretical significance and application value.

Investigation of vacuum active brazing of (HfZrTiTaNb)C high-entropy carbide ceramic to Nb with TiZrCuNi filler alloy

Good metallurgical joining was carried out between (HfZrTiTaNb)C high-entropy carbide and Nb via 37.5Ti37.5Zr15Cu10Ni (wt.%) filler alloy. The microstructure of the joint was (HfZrTiTaNb)C/(Zr, Ti)C/α-Ti + β-Ti + (Zr, Ti)2(Cu, Ni)/Zr(s, s) + β(Ti, Nb) + Nb(s, s)/Nb. The generation of (Zr, Ti)C and β(Ti, Nb)+Nb(s, s) phases between the liquid phase and ceramic and Nb were vital to realize the joining. The constituent phases of the joint did not change with the variation of brazing process parameters. When the brazing temperature rose from 920 to 1000 °C, the thickness of the (Zr, Ti)C reaction layer increased by 0.2 μm, while it remained roughly unchanged as the holding time was extended from 1 to 30 min. This unusual interfacial evolution pattern could partially attribute to the unique properties of sluggish diffusion and severe lattice distortion of the high-entropy ceramic. With the increase of brazing process parameters, the shear strength of the joints showed a mountain peak characteristic of increasing and then decreasing, and the maximum value of 154 MPa was obtained at 960 °C for 5 min. The fracture took place in the brittle (Zr, Ti)2(Cu, Ni) phase, and then passed through the (Zr, Ti)C phase and the ceramic substrate.

Growth kinetics of interfacial patterns formed by the radial displacement of an aging viscoelastic suspension

Growth kinetics of interfacial patterns formed by the radial displacement of an aging viscoelastic suspension

Immiscible displacement flows in axially rotating pipes

We experimentally study buoyant immiscible displacement flows in an axially rotating pipe, with varying flow parameters, such as the mean imposed flow velocity, density difference, pipe rotation speed, and pipe inclination angle. Via employing image processing and ultrasound Doppler velocimetry techniques, we analyze key flow features, including displacement regimes, interfacial instabilities, interfacial front velocities, and velocity and concentration fields. We find that immiscible displacement flows are distinguished by the emergence of one or two heavy fluid fronts, particularly depending on the rotation speed. Furthermore, our dimensional analysis reveals that the displacement flow is governed by four dimensionless parameters, including the Reynolds, densimetric Froude (or Archimedes), and Rossby numbers, as well as the pipe inclination angle. Using these dimensionless groups, we succeed in categorizing the main flow regimes as efficient and inefficient displacements. Moreover, we classify the interfacial regimes as stable, intermittently unstable, kinks, and separating interfacial patterns. Our analysis shows that the interfacial instabilities observed are indeed characterized by the Kelvin–Helmholtz instability. Our analysis of the velocity fields suggests remarkable differences between displacements in stationary and rotating pipes, especially in terms of the absence and presence of a countercurrent flow, respectively. Finally, our assessment of concentration fields using a Fourier transform approach provides a preliminary fundamental understanding of the characteristics of concentration waves and their corresponding amplitudes.

Numerical study of the effect of Péclet number on miscible viscous fingering with effective interfacial tension

Viscous fingering or Saffman–Taylor instability shows fingering interfacial patterns when a more mobile fluid displaces a less mobile one in porous media. The effective interfacial tension (EIT) is like capillary force, acting at the miscible interface on time scales shorter than interface relaxation. It has been numerically reported so far that the fingers are wider with EIT compared with those without EIT. A recent experiment observed finger widening with increasing flow rate in a miscible system with EIT, which is not observed in classical immiscible and miscible systems. In this study, we have numerically investigated the effect of $Pe$ (which corresponds to the injection flow rates in the experiment) on miscible viscous fingering with/without EIT. We have shown that the fingers are monotonically thinner with an increase in $Pe$ in the system without EIT, while finger widening with increasing $Pe$ is observed in the system with EIT. Furthermore, we have also examined a one-dimensional underlying concentration profile and EIT profile by using a one-dimensional diffusion–convection model because EIT is proportional to the squared concentration gradient. We have then shown that the concentration gradient is steeper and, thus, the EIT is larger as $Pe$ is larger. Therefore, this is the first numerical study that can theoretically verify finger widening with increasing flow rate, which occurs only in a miscible system with EIT to the extent of our targeting EIT values, and explain the mechanism by one-dimensional analysis.

Emergence of transient reverse fingers during radial displacement of a shear-thickening fluid

A highly sheared dense aqueous suspension of granular cornstarch particles displays rich nonlinear rheology. We had previously demonstrated the growth and onset of interfacial instabilities when shear-thinning cornstarch suspensions were displaced by a Newtonian fluid, and had suggested methods to maximise displacement efficiency [Palak, R. Sathayanath, S. K. Kalpathy and R. Bandyopadhyay, Colloids Surf. A Physicochem. Eng. Asp., 629 (2021) 127405]. In the present work, we explore the miscible displacement of a dense aqueous cornstarch suspension in its discontinuous shear-thickening regime in a quasi-two-dimensional radial Hele-Shaw cell. We systematically study the growth kinetics of the inner interface between water and the cornstarch suspension, and also of the outer interface between the suspension and air. In addition to the growth of interfacial instabilities at the inner interface, we observe a transient withdrawal of the suspension and the formation of fingering instabilities at the outer interface. We demonstrate that these `reverse fingering' instabilities are extremely sensitive to the injection flow rate of water, the gap of the Hele-Shaw cell and the concentration of the displaced cornstarch suspension, {and emerge irrespective of immiscibility between the fluid pair. We believe that as the cornstarch suspension dilates due to the high shear rate imposed by the displacing fluid, the outer suspension-air interface responds with a restoring force, resulting in the penetration of air into the suspension and the formation of reverse fingers. We note that the growth of reverse fingers significantly reduces the displacement efficiency of the suspension. Finally, we demonstrate a correlation in the growth of inner and outer interfacial patterns by computing the velocity with which stresses propagate in the confined dense suspension. Our findings are useful in understanding the flow of granular materials through constrained geometries and can be extended to study stress propagation in shear-thickening materials due to a sudden imposition of high shear rate, such as in impact behaviour.

Interfacial Degradation and Pattern Evolution of Exfoliated Graphene by Cyclic Mechanical Loading

AbstractThe interfacial interactions between 2D materials and polymer substrates receive increasing interest due to the surge of flexible electronics, multifunctional coatings, and nanocomposites. Although the strain effect on electrical, optical, and mechanical properties of 2D materials is extensively investigated, understanding the interfacial mechanics of 2D material‐polymer systems by dynamic loading is still a challenge. Here, the interfacial degradation and pattern evolution of mechanically exfoliated single‐ and few‐layer graphene on polydimethylsiloxane (PDMS) substrates by cyclic mechanical loading, are reported. It is found that the tensile strain leads to interfacial slippage between graphene and PDMS, whereas the compressive strain can be transferred to graphene with a transfer efficiency above 80%. Through cyclic loading, the graphene surface is seriously deformed by formation of multiple instability patterns including wrinkles and cracks. The morphological characteristic and evolution mechanism of the wrinkles and cracks are analyzed and discussed in detail. The interfacial adhesion energy is evaluated by wrinkle profiles and it decreases from ≈23 to ≈2 mJ m−2 as the cycle number increases. This work can promote better understanding of the interfacial effect of 2D materials on polymer substrates and controllable fabrication of various wrinkled or crumpled surfaces of 2D functional materials by cyclic mechanical loading.