Search Results (190)

Maintaining wellbore stability in deep and ultra-deep formations demands plugging agents capable of sealing nano- to micro-scale pores under high-temperature conditions. A core–shell nano-plugging agent (CSP) was synthesized via emulsion polymerization using KH-570-modified nano-SiO₂ as the rigid core and a poly(styrene-co-butyl acrylate-co-methyl methacrylate) terpolymer as the deformable shell. CSP particles had a mean diameter of 196.5 nm (polydispersity index, PDI = 0.183) and an onset decomposition temperature of 342 °C. Compatibility tests at 180 °C confirmed that 3 wt% CSP caused no adverse changes in the rheology or emulsion stability of the oil-based drilling fluid (OBM). At 180 °C, CSP reduced the high-temperature high-pressure (HTHP) filtrate loss by 64.4% and the permeability plugging apparatus (PPA) filtrate loss by 66.1%. Sand-disk tests elevated the breakthrough pressure from 1.5 to 9.2 MPa. Core displacement on sandstone cores achieved a plugging rate of 98.30%, and pressure transmission tests on natural shale cores extended the 50% equalization time by 7.8-fold. Comparative evaluation confirmed that the core–shell architecture consistently outperformed nano-SiO₂ alone, polymer alone, and their physical blend. Low-temperature N₂ adsorption provided direct evidence of pore sealing, with the treated-shale Brunauer–Emmett–Teller (BET) surface area and total pore volume reduced by about 62% (12.6 to 4.8 m²/g and 0.0325 to 0.0121 cm³/g, respectively). Scanning electron microscopy of the shale surface before and after treatment further provided direct visual evidence of pore sealing, showing the open, porous matrix being converted into a dense, compacted filter cake. Filter-cake thickness measurements are consistent with a proposed three-stage plugging mechanism—bridging, deformation filling, and thermal compaction—driven by the complementary roles of the rigid core and the deformable shell. These findings indicate that CSP merits further evaluation as a high-temperature plugging agent for wellbore stabilization in deep shale formations. Full article

Nanoemulsions are thermodynamically unstable but kinetically stable colloidal dispersion systems with droplet sizes ranging from 20 to 500 nm. With their high specific surface area, excellent optical properties, tunable rheology, and remarkable penetration ability, these systems demonstrate enormous potential in enhanced oil recovery (EOR). This paper systematically reviews the significant advances in nanoemulsion characterization techniques and oil displacement mechanisms. The nanoemulsion characterization techniques are examined, covering a comprehensive multi-scale characterization system from particle size and distribution analysis (e.g., dynamic light scattering, laser diffraction), micro-morphology and structure visualization (e.g., transmission electron microscopy, atomic force microscopy), and interface and surface property characterization (e.g., interfacial tension measurement, zeta potential analysis) to stability and rheology assessment, as well as chemical composition and structure analysis. Furthermore, core mechanisms of nanoemulsions in oil displacement processes are briefly summarized, revealing multiple synergistic enhancement mechanisms including ultra-low interfacial tension and oil film stripping, rock wettability alteration, emulsification and viscosity reduction, improved fluid flow and injection pressure reduction. Finally, prospects for the potential application of nanoemulsion oil displacement technology in the development of low-permeability, tight, and heavy oil reservoirs are described by analyzing the current challenges such as unclear structure–activity relationships, full-chain stability (including storage, transport, injection, and reservoir aging), and environmental safety, and future research directions are pointed out, including clarifying structure–activity relationships, smart responsive system development, artificial intelligence-assisted design, and pilot-scale validation. Clarifying the link between nanoemulsion characterization techniques and oil displacement mechanisms is of significant academic and engineering value for promoting the transition from empirical application to rational design of related technologies. Full article

Foam injection moulding (FIM) enables lightweight thermoplastic parts, but current process simulations do not resolve microstructure formation. This work presents a micro-scale CFD framework for FIM that captures gas–melt interaction and bubble morphology. A two-phase, compressible volume-of-fluid solver (OpenFOAM) with surface tension and viscoelastic Phan–Thien–Tanner rheology is coupled to a nucleation pre-processor based on classical nucleation theory, which places bubbles stochastically using macro-scale pressure and temperature histories. The approach was demonstrated on a plate geometry using a 2D through-thickness section to investigate bubble nucleation, deformation, coalescence, and interaction under realistic process conditions. The simulations reproduced characteristic morphology trends across the thickness. In particular, the predicted aspect ratio and orientation show the expected skin–core behaviour and agree qualitatively with experimental observations. These results demonstrate that the framework can describe morphology development beyond simplified spherical-cell assumptions and provides a proof of concept for multiscale coupling between macro-scale process conditions and micro-scale foam structure evolution. A simplified surrogate growth representation was used to enable bubble expansion; however, a physically based mass-transfer model is required for quantitatively accurate growth kinetics. Full article

Sodium caseinate (SC)-stabilized emulsions are highly susceptible to flocculation and phase separation near the protein isoelectric point (pI), limiting their application in acidified food systems. In this study, high acyl gellan gum (HA) was introduced to construct pH-responsive protein–polysaccharide complexes to modulate the interfacial assembly and stability of SC emulsions. Results demonstrated that HA interacts with SC primarily through electrostatic attraction and multi-site hydrogen bonding. This interaction induces protein conformational rearrangement and, as evidenced by combined structural and computational analyses, facilitates the assembly of a denser, interconnected composite network. The formation of HA–SC complexes significantly enhanced interfacial adsorption, reduced oil–water interfacial tension. Rheological and microrheological analyses revealed the composite system formed an elasticity-dominated weak gel network, restricting droplet mobility and suppressing aggregation. Consequently, HA–SC emulsions exhibited markedly improved pH tolerance and physical stability compared to SC-only emulsions, particularly near the pI, evidenced by reduced droplet size, lower Turbiscan stability indices, and more homogeneous microstructures. Crucially, utilizing a well-defined mechanistic model of fixed HA and SC concentrations, this study quantitatively links molecular interactions, interfacial network reconstruction, and macroscopic emulsion stability across a broad pH continuum. Rank-correlation analysis of pH-resolved descriptors shows the molecular charge state co-varies monotonically with the interfacial network and macroscopic stability, and is inversely coupled to droplet mobility. These findings provide new insights into protein–polysaccharide interfacial engineering, establishing the essential physical-stability foundation for the future rational design of acid-tolerant food emulsions and functional delivery systems. Full article

This work presents a comparative study of micro- and nano-scale fillers in liquid composite molding processes, focusing on how particle size and morphology affect resin rheology, flow behavior, and filler filtration within fiber preforms. Glass microspheres and organo-modified montmorillonite were dispersed in epoxy resin and injected through glass-mat preforms at different fiber volume fractions (ranging from 0.27 to 0.47). Our study integrates rheological characterization, in situ flow-front tracking, unsaturated permeability analysis, thermogravimetric quantification of retained particles, and microstructural observations by SEM. Despite their smaller loading, nanoclay suspensions showed a markedly higher viscosity increase than microsphere systems, yet their permeability remained nearly unchanged. In contrast, microsphere-filled resins exhibited strong filtration at the flow inlet, density-driven settling near the lower tool face, and significant permeability loss. The results demonstrate that nano-fillers, although more viscous, maintain homogeneous distribution and flow continuity, whereas micro-fillers promote cake formation and local compaction. This controlled side-by-side comparison clarifies how filler size and shape govern filtration mechanisms in liquid composite molding (LCM), providing design guidelines for processing filled resin systems without compromising part quality. Full article

Blood viscosity is strongly dependent on hematocrit, and the hematocrit–viscosity relationship is an important determinant of blood rheology under physiological and pathological conditions. However, obtaining a full hematocrit–viscosity curve requires multiple measurements over a wide hematocrit range. In this study, a simple method is proposed to reconstruct the full hematocrit–viscosity curve using only three-dataset Krieger–Dougherty (K–D) regression as $\mu ={{\mu }_0(1-{\displaystyle \frac{\varphi }{{\varphi }_m}})}^{-\alpha {\varphi }_m}$. Based on suspended blood, RBC-rich blood and RBC-depleted blood are prepared after centrifugation. The hematocrit of each type of blood is measured using a micro-hemocytometer. Simultaneously, the blood viscosity of each type of blood is measured using the coflowing streams method. The proposed method is evaluated sequentially using reference datasets and hematocrit–viscosity datasets of control blood. According to results, the full hematocrit–viscosity curve obtained from three selected datasets is in good agreement with the experimental data and yields a lower root-mean-square error than conventional methods using all datasets. The exponent of the K–D model is strongly influenced by the midpoint dataset, whereas μ₀ is mainly affected by the suspending medium (dextran solution). In contrast, GA-induced rigidified RBCs do not significantly affect μ₀ within a 0.15% concentration. In conclusion, the proposed method provides a simple, efficient, and reliable approach for estimating the full hematocrit–viscosity curve. Full article

This study aims to investigate the influence of clay mineral content on the rheological properties and long-term deformation stability of clays, and to establish a unified model capable of quantitatively describing the nonlinear rheological behavior of clays with different mineral compositions. Direct shear rheological tests were conducted on specimens prepared with different mixing ratios of bentonite, kaolin, and quartz. Combined with micro-mechanism analysis, the controlling factors of clay rheological behavior were explored. The experimental results show that the creep stress threshold, elastic viscosity, and average plastic viscosity decrease significantly with increasing clay mineral content. The rheological deformation exhibits distinct nonlinear characteristics, and clay mineral content plays a controlling role in the rheological behavior. Based on experimental and mechanistic analysis, a unified rheological model was established, which reflects the material origin of rheology and captures nonlinear rheological characteristics. This model can predict the entire time-history mechanical behavior of clays with different mineral compositions across the three stages of instantaneous deformation, decay rheology, and steady-state rheology under different shear stress levels using a single set of parameters. Validation was performed through direct shear rheological tests under 50 working conditions for five types of clay specimens, demonstrating good consistency between the model calculations and experimental results. The unified rheological model reveals the material origin and physical essence of clay rheology, demonstrates high universality, and advances the understanding of the influence of mineral composition on rheology from the current phenomenological qualitative description to quantitative calculation for the first time, significantly enhancing its engineering application value. This provides a more reliable tool for predicting long-term deformation and assessing the stability of clay foundations. Full article

Asphalt rheological properties are fundamental to pavement performance, yet their accurate assessment requires multi-scale characterization due to asphalt’s inherent complexity. This article reviews the connections between asphalt rheology across chemical, microstructural, and macro-mechanical scales, employing a methodological analysis of supramolecular and colloidal models for micro-scale behavior and dynamic shear rheometry for macro-scale properties. Current research confirms asphalt as a complex multiphase continuum, where micro-scale rheology is explained by intermolecular interactions and colloidal structures, while macro-scale analysis successfully characterizes linear viscoelasticity through established empirical and mechanical models. However, the study identifies critical gaps: nonlinear viscoelastic characterization under large-amplitude oscillatory shear (LAOS) remains underdeveloped, and fundamental issues like directly probing molecular interactions and the origin of microstructures like the “bee structure” are unresolved. The primary conclusion is that a comprehensive understanding of asphalt rheology hinges on future research that integrates experimental and simulation data across these scales to bridge the gaps between chemical composition, microstructure, and macroscopic performance. Full article

The evaporation of a thin liquid film representative of power-law rheology flowing along an inclined channel wall under the combined influence of gravity and surface tension is investigated using a semi-analytical modelling framework. The evolution of film thickness, heat transfer characteristics, and dry-out behaviour are examined as functions of the power-law exponent, Weber number, and inlet film thickness. The results show that a decrease in the power-law exponent leads to a slower reduction in film thickness, resulting in a significant increase in the dry-out length for a fixed value of consistency. This behaviour is attributed to the large effective viscosity developing near the free surface for shear-thinning fluids, in contrast to the negligible surface viscosity observed for shear-thickening fluids. The local Nusselt number increases gradually along the flow direction, followed by a sharp terminal rise marking the onset of dry-out. The mean Nusselt number decreases with increasing power-law exponent, which is consistent with the dry-out length variation with the power-law exponent. The dry-out length is found to be largely insensitive to surface tension for a fixed normalised inlet film thickness, while exhibiting an approximately linear dependence on the inlet film thickness that is nearly independent of the power-law index. Overall, the study establishes a hierarchy of controlling parameters for evaporating power-law films in inclined micro-channels, demonstrating that inlet film thickness primarily governs the dry-out location, while rheology and surface tension exert secondary influences within the parameter ranges considered. Full article

Electrophysiology, mechanobiology, and the study of soft matter within cells demonstrate increasing amounts of evidence that neuronal signaling arises from interactions between membrane potential, force, and phase. Herein, we have attempted to collect and organize the evidence for each of these areas of study into an approximate structure called the electromechanical connectome: a three-way state–space (membrane potentials, nanoscale mechanical forces, and cytoplasmic rheology, including phase-separated liquid–liquid droplets) where membrane potentials, nanoscale mechanical forces, and cytoplasmic rheology, and phase-separated liquid–liquid droplets are likely to influence one another, influencing synaptic processing, plasticity and network stability. We will also attempt to illustrate the following: how changes in electrostatic fields can be used to alter the arrangement of lipids, hydration, and dielectric microdomains, and the contact geometry between organelles and activity dependent transcription; how mechanical dynamics associated with spines, axons, and the active zone of synapses may be used to modify the energy landscape of channels, the docking and priming of vesicles, and the transport of cytoskeletons; and how viscosity corridors, along with phase-separated micro-reactors, can be used to regulate the kinetics of signaling, molecular trafficking and metabolic processes in local environments. With these connections in mind, we will propose a multiphysical attractor model in which cognition is the result of navigating through metastable manifolds, while neurodegenerative disease may be a result of the progressive loss of electromechanical coherence, phase boundary control and energetic flexibility. Finally, we will present testable hypotheses and use AI-enabled digital twin methods to potentially quantify the early deformation of manifolds and provide precision biomarkers and therapeutic options. Full article

Severe fluid loss in fractured, depleted reservoirs usually defeat conventional water-based drilling fluids (WBDFs), and rigid lost-circulation materials (LCMs) struggle to form durable, conformal seals. We report an eco-oriented colloidal gas aphron (CGA) fluid built from a nanostructured corn biopolymer (NCBP) and a biodegradable peanut-oil-derived surfactant, benchmarked against a reference fluid (RF) and aphron-only baselines (aphron based fluid, ABF). NCBP, produced by ball milling, was confirmed nanostructured by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), electron and atomic microscopies. Performance was evaluated from 25 to 90 °C for rheology, aphron stability and filtration at low temperature and low pressure (LTLP) of 100 psi and 25 °C, with post-test mud cake imaging. The optimized formulation, NCBP-2, showed stronger shear-thinning and higher gel strengths with heat, sustained stable and uniform aphrons for at least 120 min with foam persistence beyond 24 h, and delivered 3.0 mL filtrate with a 0.8 mm mud cake. These outcomes correspond to 60% less filtrate and approximately 73% thinner mud cakes than RF (7.5 mL; 3.0 mm), and about 14% and 33% improvements over the best ABF (3.5 mL; 1.2 mm). Micrographs revealed denser, finer-pored mud cakes, consistent with a mechanism in which deformable aphrons bridge micro-fractures while nano-scale polymeric fillers tighten the mud cake network. The results demonstrate decisive loss-control gains with temperature-tolerant rheology, supporting bio-based CGA fluids for depleted and fractured formations. Full article

This study investigated the effects of adding Lactobacillus helveticus H11 on the fermentation characteristics, storage performance, and probiotic functionality of brown fermented milk. The results were obtained by analyzing the microrheological properties during the fermentation process, as well as changes in titratable acidity, viable cell count, texture, ACE (angiotensin-converting enzyme) inhibition rate, and metabolite profiles during storage. The findings indicated that the addition of H11 significantly shortened the fermentation time of brown fermented milk and improved its gel structure. Simultaneously, it delayed the post-acidification phenomenon during storage, enhancing storage stability. Moreover, it enhanced the ACE inhibitory activity of the product, demonstrating potential antihypertensive health benefits. Metabolomic analysis further revealed that H11 promoted the production of flavor compounds, such as phenylacetaldehyde and phenyllactic acid, enriching the flavor diversity. Additionally, it concurrently regulated the metabolism of tyrosine and vitamin B6. These discoveries provide a scientific basis for the commercial development of brown probiotic products. Full article

Unconventional low-permeability reservoirs present significant production challenges due to the poor imbibition and displacement efficiency of conventional polymer fracturing fluids. The injection of nanoparticle (NP) compounds into polymer fracturing fluid base systems, such as linear gels or slickwater, has garnered significant research interest due to their superior performance. However, previous studies have primarily focused on evaluating the fluid’s properties, while its imbibition and oil displacement mechanisms within reservoirs remain unclear. Herein, the imbibition mechanism of nanoparticle composite polymer fracturing fluid was systematically investigated from macro and micro perspectives using low-field nuclear magnetic resonance (LF-NMR), atomic force microscopy (AFM), interfacial rheology, and other technical means. The results showed that the imbibition recovery using polymer fracturing fluid was 10.91% higher than that achieved with conventional slickwater. Small and medium pores were identified as the primary contributors to oil drainage. Nanoparticles can be adsorbed on the rock wall in the deep reservoir to realize wettability reversal from oil-wet to water-wet, reducing crude oil adhesion. Furthermore, a strong interaction between the adsorbed NPs and cleanup agents at the oil–water interface was observed, which reduces interfacial tension to 0.95 mN·m⁻¹, mitigates the Jamin effect, and enhances interfacial film deformability. NPs increase the interfacial dilatational modulus from 6.0 to 14.4 mN·m⁻¹, accelerating fluid exchange and oil stripping. This work provides a consolidated mechanistic framework linking NP-induced interfacial modifications to enhanced pore-scale drainage, offering a scientific basis for designing next-generation fracturing fluids. We conclude that NP-compound systems hold strong potential for low-permeability reservoir development, and future efforts must focus on optimizing NP parameters for specific reservoir conditions and overcoming scalability challenges for field deployment. Full article

Wellbore instability in shale formations represents a worldwide challenge in drilling engineering. The development of high-performance shale stabilizers is crucial for enhancing wellbore stability. A core–shell structured shale stabilizer, designated AAD-CaCO₃, was synthesized via inverse emulsion polymerization using acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and dimethyl diallyl ammonium chloride (DMDAAC) as monomers. Nano-CaCO₃ was generated in situ by reacting calcium chloride and sodium carbonate. Sodium bisulfite and ammonium persulfate were used as initiators. The product was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). Its effects on the rheological properties and filtration performance of a bentonite-based mud were evaluated. The stabilizer’s efficacy in inhibiting shale hydration swelling and dispersion was evaluated through linear swelling tests and shale rolling dispersion experiments, while its plugging performance was examined via a filtration loss test with a nanoporous membrane and spontaneous imbibition tests. The results indicated that AAD-CaCO₃ possesses a core–shell structure with the nano-CaCO₃ encapsulated by the polymer. It moderately improved the rheology of the bentonite-based mud and significantly reduced both the low-temperature and low-pressure (LTLP) filtration loss and the high-temperature and high-pressure (HTHP) filtration loss. AAD-CaCO₃ could be adsorbed onto shale surfaces through electrostatic attraction, resulting in substantially reduced clay hydration swelling and an increased shale cutting recovery rate. Effective plugging of micro-nanopores in shale was achieved, demonstrating a dual mechanism of chemical inhibition and physical plugging. Full article

Cleaning historical silk textiles is a particularly sensitive operation that requires precise control to prevent mechanical or chemical damage. In this study, we investigate using flexible PVA–borax-based gels to remove soot from silk, i.e., polyvinyl alcohol–borax (PVA-B) gels and polyvinyl alcohol–borax–agarose double network gels (PVA-B/AG DN) loaded with different cleaning agents—namely, 30% ethanol and 1% Ecosurf EH-6—in addition to plain gels loaded with water. These gel formulations were tested on simplified model systems (SMS) and were applied using two methods: placing and tamping. The cleaning results were compared with a traditional contact-cleaning approach; micro-vacuuming followed by sponging. Visual inspection, 3D opto-digital microscopy, colorimetry, and machine-learning-assisted (ML) soot counting were exploited for the assessment of cleaning efficacy. Rheological characterization provided information about the flexibility and handling properties of the different gel formulations. Among the tested systems, the DN gel containing only water, applied by tamping, was easy to handle and demonstrated the highest soot-removal effectiveness without leaving residues, as confirmed by micro-Fourier Transform Infrared (micro-FTIR) analysis. Scanning electron microscope (SEM) micrographs proved the structural integrity of the treated silk fibers. Overall, this work allows us to conclude that PVA–borax-based gels offer an effective, adaptable, and low-risk cleaning strategy for historical silk fabrics. Full article