Search Results (4,128)

An integrated numerical method is proposed for analyzing the nonlinear seismic response of near-fault building clusters, comprising three algorithms: (1) a structural investigated lump algorithm for elastoplastic dynamic response of structure; (2) a connecting investigated lump algorithm for bidirectional wave propagation between the site and elastoplastic building clusters; (3) a geomedia investigated lump algorithm for seismic wave propagation with an improved viscoelastic constitutive model, which allows independent definition of P/S-wave quality factors to characterize geomedia attenuation. Validated for its capability in simulating site-city dynamic interaction problems via a shaking table test, the method is applied to study the seismic response of near-fault building clusters in Xichang City under a hypothetical M_w6.8 earthquake. It is shown that irrespective of whether shallow geological structures are considered, clusters (c2–c4) situated in rupture-forward surface area within ~1.5 km of the fault trace entered the elastoplastic stage, while others (c1, c5) remained elastic. Shallow geological structures may reverse locally hanging-wall/footwall effects of both near-fault structural seismic response and ground motion. A notable seismic-response characteristic of near-fault structures undergoing the elastoplastic stage is that the permanent structural motion displacement (PSMD) at the slab of a specific floor incorporates not only the non-zero permanent ground motion displacement (PGMD) but also the non-zero final structural residual displacement (FSRD) relative to the supporting ground. The developed method could provide support for seismic damage assessment, site selection, and structural optimization design of near-fault building clusters. Full article

Resolving the dichotomy between wide detection ranges and low mechanical hysteresis remains a critical challenge in flexible electronics, largely governed by the intrinsic viscoelastic creep of polymeric dielectrics. Drawing inspiration from the distinctive load-bearing mechanisms of traditional Chinese Sparrow Brace architecture, we report a mechanically optimized tilted micro-architecture designed to enhance structural resilience. Unlike conventional soft elastomeric pillars that easily succumb to mechanical failure, this BOPS-based tilted geometry provides excellent load-bearing capacity, effectively preventing premature failure. Finite element analysis (FEA) confirms that this tilted geometry forces a fundamental shift from conventional bulk compression to structural bending. Because this bending-dominated architecture drives rapid elastic recovery, it significantly mitigates the severe effects of the polymer’s viscoelastic creep under the tested loading conditions, achieving reliable signal reversibility with low hysteresis. We fabricated this specific architecture via programmable femtosecond laser direct writing (FsLDW) on biaxially oriented polystyrene (BOPS) films, harnessing the material’s entropy-driven self-growth kinetics. By merging this localized growth mechanism with the architectural design, we effectively bypassed the complexities of traditional molding, achieving mask-free, in situ growth of large-scale, highly uniform dielectric micro-arrays. The resulting sensor delivers a remarkably broad working range (up to ~2.28 MPa) coupled with a negligible recovery error (~1.3%), an agile dynamic response (~70/80 ms), and consistent operational durability. Ultimately, this work combines architecture-inspired structural design with advanced femtosecond laser surface microengineering, providing a conceptually novel and scalable pathway for next-generation flexible sensing. Full article

Water-based fracturing fluids, which are essential for enhancing oil and gas production, increasingly utilize seawater or produced water as alternatives to freshwater due to scarcity and cost considerations. However, the high salinity of these alternative water sources can compromise fluid stability and induce formation damage. Herein, the rheological behavior of borate-crosslinked hydroxypropyl guar (HPG) fracturing fluids was systematically evaluated in the presence of individual salts to elucidate the effects of ionic composition and concentration. Viscosity measurements at 80 °C and 170 s⁻¹ revealed that Ca²⁺ above 1500 mg/L reduced viscosity to below 50 mPa·s within 50 min, whereas Na⁺, K⁺, Mg²⁺ and SO₄²⁻ up to 10,000 mg/L exhibited no significant influence on viscosity and shear resistance. Among the cations investigated, Fe³⁺ exerted the most severe effect: only 15 mg/L Fe³⁺ caused viscosity to drop below 50 mPa·s within 30 min, far below the requirement for field applications. At elevated concentrations, MgCl₂, CaCl₂ and FeCl₃ compromised gel structural strength, while KCl-containing fluids demonstrated superior elastic resistance compared to NaCl at equivalent high concentrations. Microstructural analysis by SEM revealed that Na⁺, K⁺ and Mg²⁺ enhanced polymer hydration and HPG fiber entanglement, promoting the formation of well-defined network structures. In contrast, Ca²⁺ and Fe³⁺ disrupted the crosslinked gel architecture through complexation and electrostatic interactions with the polymer, resulting in reduced structural integrity. These findings provide critical insights for formulating fracturing fluids using saline or recycled water sources and inform targeted pretreatment strategies for flowback water in hydraulic fracturing operations. Full article

Poly(ethylene terephthalate) (PET) composites reinforced with reduced graphene oxide (rGO) were investigated in order to elucidate the influence of nanofiller concentration and compatibilization on the viscoelastic relaxation behavior across the glass transition. Composites containing 0.1 and 0.5 wt% rGO were prepared by melt blending, and selected systems incorporated 5 wt% of an ionomeric polyester (PETi) as compatibilizer to enhance interfacial adhesion. The thermomechanical response was characterized using dynamic mechanical analysis (DMA) as a function of temperature. Experimental results revealed a strong dependence of stiffness, damping, and glass transition behavior on filler concentration and interfacial interactions. While low rGO loading produced minor changes, the incorporation of 0.5 wt% rGO significantly increased the glassy modulus and shifted the glass transition temperature, indicating restricted segmental mobility. Compatibilized systems exhibited further stiffness enhancement and modified relaxation dynamics due to improved stress transfer and interphase development. To capture the distributed nature of the relaxation processes, the glass transition region was modeled using a fractional Zener model (FZM) with two spring-pot elements within a cooperative relaxation framework. The model successfully reproduced the experimental $E^{\prime }$ and $tan\delta$ curves and revealed systematic variations in the fractional exponents and cooperative parameters. The results demonstrate that the introduction of rGO and compatibilizer progressively transforms the relaxation spectrum of PET from a relatively uniform segmental process into a heterogeneous, interfacially mediated viscoelastic response that is naturally described by fractional rheology. Full article

This paper presents a novel proportional–integral–derivative (PID) control framework for first $\alpha$-order systems evolving in fractal time. The main contribution is the extension of classical control theory to systems exhibiting anomalous temporal scaling by employing local fractal derivatives. In contrast to fractional-order PID (FOPID) approaches, which primarily model memory effects, the proposed fractal PID framework captures time-scaling behavior arising in non-smooth environments, such as viscoelastic friction and irregular contact surfaces. The closed-loop dynamics are formulated as a second $\alpha$-order fractal differential equation, from which a characteristic equation is derived to establish conditions for asymptotic stability. It is shown that, for a constant reference input and positive controller gains, the tracking error converges to zero as $t\to \infty$. In addition, a quantitative performance analysis demonstrates that the fractal-order $\alpha$ governs temporal stretching: smaller values of $\alpha$ lead to increased rise and settling times and reduced oscillation frequency. The effectiveness of the proposed approach is illustrated through applications to a thermal system with fractal heat input and robotic actuators operating in irregular environments. These results highlight the potential of fractal-time control as a systematic framework for modeling and controlling dynamical systems with non-integer temporal structure. Full article

This study presents a data-driven framework for the mechanistic interpretation of asphalt pavement responses using an integrated smart sensing and monitoring system deployed on a national highway in Thailand. A fully instrumented pavement test section was developed, incorporating a multi-sensor embedded network and a field data acquisition platform integrated with weigh-in-motion (WIM) technology. The system consists of 54 sensors, including strain gauges, pressure cells, moisture sensors, and thermocouples, installed at multiple depths to capture high-resolution stress–strain responses under controlled heavy-vehicle loading. Field measurements were analyzed and compared with classical mechanistic models, including Boussinesq’s theory, Odemark’s equivalent thickness method, and Burmister’s multilayer elastic theory. The results demonstrate good agreement for vertical stress predictions in deeper layers, while significant discrepancies were observed in strain responses, particularly in the asphalt layer, where measured tensile strains were up to 2.5 times higher than theoretical estimates. The findings indicate that conventional elastic models provide useful first-order approximations; however, discrepancies were observed in representing the viscoelastic behavior of asphalt materials under real loading conditions. Furthermore, the integration of sensor data with traffic loading information confirms that axle load magnitude is the dominant factor governing pavement responses, whereas vehicle speed primarily influences load duration. The proposed framework demonstrates the potential of smart sensing systems for enabling automated, data-driven pavement analysis and supporting digital twin-based infrastructure management. Full article

This study developed a microemulsion system based on diatomaceous earth (DE) for the topical delivery of resveratrol. The microemulsions were prepared using pseudo-ternary phase diagrams. A 4:1 ethanol:virgin coconut oil ratio resulted in a larger microemulsion region than a 3:1 ratio. Two formulations with oil (ethanol:virgin coconut oil, 3:1):Cremophor RH40:water ratios of 1:5:4 (ME1) and 2:5:3 (ME2) were selected for resveratrol loading and subsequently combined with DE at ratios of DE:microemulsion (DE:ME) 0.5:1, 0.5:2, and 0.5:3. The transmission electron microscopy images demonstrated the different microstructures of the microemulsions. Rheological analysis revealed an increase in storage modulus and a decrease in the linear viscoelastic region with increasing DE concentration, particularly in ME1. Differential scanning calorimetry showed disruption of boundary water following DE incorporation. Fourier-transform infrared spectroscopy indicated primarily physical interactions between resveratrol and the DE:ME system. DE:ME demonstrated high resveratrol content, approaching 100%. DE:ME1 0.5:2 significantly enhanced resveratrol permeation, resulting in a 3-fold increase compared with the microemulsion alone after 8 h. DE:ME1 0.5:2 and DE:ME2 0.5:3 enhanced the photostability of resveratrol and the formulations remained stable after storage at 40 °C for 6 months. The DE:ME system maintained its cellular uptake capability, preserved the biological activity of resveratrol, and exhibited low cytotoxicity in human keratinocytes, with cell viability remaining above 70%. These results highlight the potential of DE-based systems for incorporating microemulsions of low-water soluble photo-sensitizing substances in topical drug delivery applications. Full article

This study addresses the need for enhanced oil recovery (EOR) in mature reservoirs, particularly in Russian oil fields that have undergone prolonged production and exhibit declining performance. Among EOR techniques, polymer flooding remains one of the most widely applied and effective methods following conventional waterflooding. In this work, the rheological and viscoelastic behavior of partially hydrolyzed polyacrylamide (HPAM) solutions and their impact on oil displacement efficiency in heterogeneous reservoirs were investigated. Two polymers with different molecular weights were evaluated using steady shear, oscillatory rheology, and one-dimensional core flooding experiments. The results revealed pronounced shear-thinning behavior, with viscosity increasing with polymer concentration and molecular weight. Viscoelasticity was observed only for the high-molecular-weight polymer, characterized by a well-defined linear viscoelastic region and relaxation behavior sensitive to pore size, salinity, and temperature. Core flooding experiments showed that waterflooding recovered 30–31% OOIP, while high-molecular-weight polymer injection increased recovery to ~62% OOIP. In contrast, low-molecular-weight polymer yielded only ~40% OOIP, whereas a combined injection strategy achieved up to 74–76% OOIP. These findings highlight the critical role of polymer molecular weight and viscoelasticity in improving sweep efficiency and enhancing oil recovery in heterogeneous reservoirs. Full article

Gingival recession is commonly linked to alveolar bone dehiscence, inflammatory burden, traumatic brushing, or excessive orthodontic forces. However, recession is also observed in some patients despite apparently mild or “biologically acceptable” loading, particularly in thin periodontal phenotypes. Here, we propose the Gingival Creep Failure Theory, a hypothesis-driven conceptual framework in which gingival soft tissues undergo time-dependent viscoelastic deformation (creep) under sustained or repetitive tensile microstrain. Over time, accumulated deformation and microstructural fatigue may reduce recoil capacity and shift the gingival margin apically once tissue-level tolerance is exceeded. Gingival connective tissue is modeled as a fiber-reinforced, fluid-rich viscoelastic composite whose response depends on collagen architecture, cross-linking, proteoglycan-mediated hydration, and vascular support. In thin phenotypes characterized by reduced connective tissue volume and altered extracellular matrix (ECM) organization, creep progression is hypothesized to accelerate, lowering the threshold at which fatigue-related microdamage translates into clinically detectable marginal migration. Evidence from collagenous connective tissue biomechanics supports the plausibility that sub-failure sustained or cyclic loading can produce cumulative deformation and incomplete recovery; however, direct creep–fatigue data for human gingiva remain limited, underscoring the need for targeted validation studies. This hypothesis integrates soft tissue mechanics with periodontal phenotype biology and orthodontic loading patterns and proposes creep and microstructural fatigue as plausible time-dependent contributors to gingival recession in susceptible phenotypes. Because direct in vivo gingival strain and creep–fatigue measurements remain limited, the model should be interpreted as hypothesis-generating and in need of targeted clinical and experimental validation. Full article

Oil–water emulsions constitute essential components in a wide range of industries. Despite their extensive use in emulsion systems, synthetic emulsifiers are often associated with environmental concerns and high costs. In this study, lignin—a by-product of the pulping industry—was polymerized with acrylic acid and employed as an emulsifier in a xylene–water system to address this challenge. When testing two lignin–acrylic acid copolymers, the results confirmed that the one possessing a higher molecular weight (7.99 × 10⁵ g/mol) and charge density (4.7 mmol/g) (KL-AA-10) generated xylene–water emulsions with improved stability, and higher viscosity and viscoelastic moduli. These observations were consistent with the greater adsorption of this polymer, relative to the counterparts with a lower molecular weight and charge density at the xylene–water interface, as monitored using a Quartz Crystal Microbalance. The adsorption of KL-AA-10 resulted in the formation of smaller emulsion droplets (D50 = 0.6 µm) within the system, as evidenced by confocal microscopy analysis. This study underscores the potential of lignin as a renewable emulsifier for diverse applications. Full article

Muco-obstructive lung diseases, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), and bronchiectasis, are characterized by the accumulation of highly viscoelastic mucus that compromises mucociliary clearance and fosters infection and inflammation. Mucoactive therapy, encompassing both true mucolytics and non-cleaving agents, seeks to restore airway patency by altering mucus structure, hydration, and transport properties, yet its clinical impact remains variable. This narrative review provides a critical reappraisal of the pharmacological actions and therapeutic outcomes of the main mucolytic agents: N-acetylcysteine (NAC), erdosteine, carbocisteine, bromhexine, ambroxol, and dornase alfa. Beyond their classical role in reducing mucus viscosity, these drugs exhibit pleiotropic effects, including antioxidant, anti-inflammatory, and immunomodulatory activities. Specifically, for thiol-based compounds, the action consists of breaking the disulfide bonds that stabilize the mucin network; for carbocisteine, it lies in modulating mucin glycosylation and chloride transport. Ambroxol and bromhexine act by stimulating surfactant secretion and enhancing mucociliary clearance. Finally, dornase alfa exerts an enzymatic effect on extracellular DNA, a key contributor to the tenacity of mucus in cystic fibrosis. Clinical evidence indicates that NAC and erdosteine can reduce exacerbation rates in COPD, carbocisteine shows benefit with prolonged administration, and dornase alfa remains a cornerstone in CF management. However, therapeutic efficacy is constrained by heterogeneous mucus composition, pharmacokinetic limitations, and disease-specific variability. A key interpretative message is that clinical benefit appears greatest when the dominant biophysical determinant of mucus pathology is specifically targeted, supporting a transition from broad disease-label prescribing to mechanism-informed, phenotype-aware mucolytic therapy. Emerging strategies, such as agents targeting mucin–DNA interactions and advanced inhalation delivery systems, promise improved specificity and durability. By integrating mechanistic insights with clinical data, this review underscores the need for personalized mucolytic therapy and innovative approaches to overcome current challenges in managing muco-obstructive lung diseases. Full article

Background/Objectives: The objective of this study was to map and synthesize the current evidence on hemostasis in chronic and acute liver disease within the framework of Patient Blood Management (PBM). Methods: Because research in this field is heterogeneous—spanning mechanistic studies, observational data, randomized controlled trials, guidelines, and expert reviews—a scoping review was selected to comprehensively map concepts. Findings were synthesized narratively to reflect the breadth and heterogeneity of available research. Results: Hemostasis in liver disease is characterized by a fragile state of rebalanced coagulation, where parallel reductions in pro- and anticoagulant factors coexist with variable fibrinolytic disturbances and thrombocytopenia. Conventional coagulation tests (CCTs) do not accurately reflect bleeding risk, whereas viscoelastic assays and thrombomodulin-modified thrombin generation testing provide a more physiologic assessment, though with limitations. Most bleeding events arise from portal hypertension rather than coagulopathy, and the routine prophylactic correction of abnormal results of CCTs is not supported by evidence. PBM-aligned strategies—such as restrictive transfusion, targeted fibrinogen replacement, and use of thrombopoietin receptor agonists (TPO-RAs)—reduce unnecessary blood product use. Thrombosis burden is increasingly recognized in this patient population. Anticoagulation is generally safe when individualized to liver function and clinical context, however significant variability persists in clinical practice, and high-quality data remain limited for advanced disease. Conclusions: Hemostasis in liver disease reflects a dynamic and unstable equilibrium rather than a simple bleeding tendency. Diagnostic and therapeutic strategies grounded in PBM principles improve safety by avoiding unnecessary transfusion and emphasize individualized care. Despite advances in understanding rebalanced hemostasis, major gaps remain in predicting thrombotic risk, standardizing advanced coagulation testing, and defining optimal management across disease stages. Full article

Background/Objectives: This study aimed to evaluate the differences between two blood product transfusion protocols [a standard coagulation (SC) group and a rotational thromboelastometry (ROTEM) group] in patients with decompensated liver cirrhosis (LC) undergoing high-bleeding-risk endoscopic procedures. Methods: Between December 2024 and March 2025, we conducted a prospective cohort study including adult decompensated cirrhotic patients who needed prophylactic blood product transfusion before high-bleeding-risk endoscopic procedures. The prophylactic blood product transfusion strategy in the SC group was based on conventional coagulation tests (INR, platelets, and fibrinogen), and in the ROTEM group on viscoelastic parameters. Results: A total of 72 patients were included in this study (36 patients in each group); most were male (63.9%), Child–Pugh B (54.2%), and had LC with a predominance of alcoholic etiology (51.4%). There were no clinically significant differences regarding the baseline characteristics between the study groups. The most frequent endoscopic procedure was polypectomy (76.4%). Postinterventional bleeding occurred after eight procedures in the SC group and after four procedures in the ROTEM group (p = 0.206). Endoscopic hemostasis was effective. Patients from the ROTEM group received fewer FFP transfusions than the SC group (5.6% vs. 69.4%; p < 0.0001). Blood product transfusion was needed less in patients evaluated using ROTEM compared with the SC group (41.2% vs. 100%; p < 0.0001). There were no differences in the length of hospital stay (p = 0.618) or 30-day mortality (p = 0.643) between the two study groups. Conclusions: ROTEM-guided transfusion management was associated with a significant reduction in blood product use compared with standard coagulation test-based management. However, this difference should be interpreted in the context of the distinct transfusion thresholds applied in the two groups, as the standard coagulation arm followed predefined laboratory-based criteria that may have increased the likelihood of prophylactic transfusion. No statistically significant differences were observed in bleeding complications, length of hospital stay, or 30-day mortality. Therefore, these findings reflect differences in transfusion strategies rather than demonstrating clinical superiority of ROTEM-based management and should be considered preliminary. Full article

Functionally graded multi-material thermoplastic architectures provide a promising route for tailoring viscoelastic energy dissipation through controlled phase contrast and interfacial interactions. However, rational selection of optimal material compositions remains challenging due to competing requirements among stiffness, damping efficiency, thermal stability, and processability. The absence of a quantitative decision framework often limits systematic design of architected polymer systems. This study proposes an Analytic Hierarchy Process (AHP)-based multi-criteria decision model to identify the optimal rigid–elastic thermoplastic composition for enhanced damping performance. Nine performance criteria were considered, including storage modulus, loss factor, damping bandwidth, interfacial adhesion strength, elongation at break, impact resistance, glass transition temperature, thermal stability, and printability. Fourteen alternative material configurations combining different rigid phases, elastomeric interlayers, filler contents, and layer thickness ratios were evaluated. Pairwise comparison matrices were constructed based on experimentally measured thermomechanical data and literature-reported values, and consistency ratios were maintained below 0.1 to ensure decision reliability. Numerical results indicate that a graded PLA/soft-TPU/PLA architecture with optimized layer thickness ratio achieved the highest global priority weight (0.431), outperforming the baseline PLA/TPU system by approximately ~25–30% in overall performance index. Sensitivity analysis confirmed ranking robustness across variations in damping and stiffness weighting factors. The proposed framework establishes a systematic methodology for polymer material selection and multi-material architectural optimization, enabling data-driven design of thermoplastic systems with tunable viscoelastic performance. Full article

Extrusion-based bioprinting faces significant challenges in achieving the shape fidelity and internal porosity necessary for cell viability, often hindered by subjective assessment methods. This study investigated the relationship between rheological properties and print quality using a natural polymer biomaterial ink composed of 12% gelatin, 5% alginate, and 1% carboxymethylcellulose. We conducted a comparative analysis between traditional pneumatic systems and screw-driven volumetric extrusion, utilizing a suite of quantitative metrics: Spreading Ratio (SR), Printability Index (P_r), Uniformity Ratio (UF), Collapse Angle (θ), and evaluated porosity. Our results demonstrate that the screw-driven system’s positive displacement mechanism provides superior control over filament morphology by enabling precise volumetric modulation. While the pneumatic system exhibited a high SR of 1.82 and the lowest porosity at 59.92%, the screw-driven system allowed for “under-extrusion” to compensate for viscoelastic die swell. Reducing the flow rate to 50% in the screw system lowered the SR to 1.09, nearly matching the nozzle diameter, and increased porosity to 76.46%. Furthermore, the screw-driven system achieved an ideal P_r of 1.0, whereas the pneumatic system produced distorted, rounded pores with a P_r of 1.57. The findings indicate that screw-driven extruders can decouple line complex rheology from the printing process, allowing for finer spatial resolution and better pore interconnectivity. Full article