Search Results (325)

A one-pot strategy was developed for preparing a chitosan/Mg–Fe layered double hydroxide (LDH) composite by alkaline coprecipitation from an acidic chitosan solution containing Mg(II) and Fe(III) precursors, avoiding separate LDH synthesis and subsequent incorporation into chitosan. X-ray diffraction confirmed LDH formation within the chitosan matrix, and ICP analysis indicated an LDH-equivalent content of approximately 4.1 wt.% on an anhydrous basis. The composite exhibited enhanced chromate adsorption compared with both starting components. The experimental plateau adsorption capacity reached 137.4 mg/g, exceeding those of chitosan (92.2 mg/g) and Mg–Fe LDH (53.5 mg/g). Nonlinear isotherm fitting showed that Mg–Fe LDH was better described by the Freundlich model, whereas chitosan and the composite were better described by the Langmuir model. The kinetic behavior followed the pseudo-second-order equation, while Weber–Morris analysis indicated multistep uptake involving surface interaction and diffusion-related processes. In simulated groundwater containing chloride, bicarbonate, and sulfate, the composite removed 82% of Cr(VI) at 1.0 g/L. It also retained complete chromate uptake over five sorption/desorption cycles, although desorption efficiency decreased from 97.3% to 90.3%. A limitation of this study is that performance was evaluated mainly in batch systems and simplified simulated groundwater; validation with real contaminated waters and dynamic flow conditions is still required. Full article

Alginate hydrogels offer mild ionic gelation and tunable porosity for drug delivery, yet their hydrophilic, macroporous networks suffer from rapid initial burst release of water-soluble payloads. Here we introduce a hierarchical barrier-engineering strategy in which poly(D,L-lactide-co-glycolide)/poly(ethylene glycol) (PLGA/PEG) blend coatings are applied via dip-coating to Ca²⁺-cross-linked alginate beads (~1 mm) and microgels (~100 µm). For beads, three-cycle PLGA/PEG multilayer coating suppressed the initial swelling rate (dQ/dt) by ~50% and reduced 1 h burst release from >85% to ~60%, functioning as an “early-burst buffer” rather than a long-term depot. For microgels, a single PLGA/PEG layer partially attenuated burst release; however, an additional PLGA outer shell (double-barrier architecture) shifted the release-governing mechanism from swelling-dominated to diffusion-barrier-dominated control, limiting 10 min release to <10%. Core–shell formation was verified by confocal laser scanning microscopy (CLSM), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS); thermogravimetric analysis (TGA) showed ~73–79% coating retention after 9 days in phosphate-buffered saline (PBS, 37 °C). A vacuum re-loading process further improved encapsulation efficiency (>50% for beads, >20% for microgels) without compromising gel integrity. In beads, burst control was governed by swelling suppression; in microgels, the additional PLGA shell shifted control to diffusion-barrier-dominated release, demonstrating that barrier architecture must be adapted to particle scale. Full article

This study proposed an effective capacitance (C_ec) for bare and conducting polymer-covered electrodes using electrochemical impedance spectroscopy (EIS). Bare electrodes show three regimes: potential-dependent Helmholtz capacitance, Gouy–Chapman–Stern diffusion capacitance (1 MHz–10 Hz), and complex low-frequency responses, deviating from semi-infinite Warburg diffusion (1 Hz–10 MHz). Polyaniline (PANI) and poly(3,4-ethylenedioxythiophene) PEDOT-based electrodes exhibit larger potential-dependent diffusion pseudocapacitance (1 MHz–10 Hz) and the absence of a Warburg tail or a nearly horizontal low-frequency slope at 0.01–0.026 (1 Hz–10 MHz). A high-frequency C_ec of a PANI membrane correlates with bulk electrolyte concentration, while bare electrodes are less affected and dominated by Helmholtz capacitance. The equivalent circuit of the time-dependent EIS impedance spectrum for bare electrodes and PANI and PEDOT-based electrodes shows parallel capacitor behavior in combination with high-frequency capacitance (1 MHz–10 Hz) and a low-frequency response (1 Hz–10 MHz). The mathematical simulation of effective capacitance C_ec with respect to time period t (f⁻¹) follows two time constants (τ = RC), representing double-layer capacitance or pseudocapacitance (τ₁) and complex low-frequency responses or Warburg diffusion (τ₂) for bare electrodes and conducting polymer-based electrodes, respectively. This simulation analysis also elucidates the frequency dependence of the Warburg characteristic frequency (ω) and the extension of the double-layer capacitance diffuse distance L_D for H⁺ with GC electrodes to approximately 0.74~1.51 mm over a time interval of ca. 1 s (t = f⁻¹). The diffusion coefficient D_i of K⁺ ion transfer through a PEDOT solid contact from 1 mC (0.1 µm) to 10 mC (1 µm) is in the range of 0.57–12 × 10⁻¹⁴ cm²·s⁻¹, following a power law with an exponent of 1.75 with respect to the polymerization time of PEDOT, which is inconsistent with Fick’s law. Full article

Achieving the coexistence of high energy density and fast-charging capability remains a fundamental challenge for lithium-ion batteries. Increasing electrode thickness and compaction density enhances energy density but simultaneously alters the pore structure and restricts lithium-ion transport, leading to concentration polarization, increased resistance, and lithium plating. In this work, we employ X-ray computed tomography (X-CT) and 3D reconstruction to establish quantitative relationships between particle size, compaction density, and key structural parameters (porosity, tortuosity, effective proportion of lithium-ion flux (f_eff)). Then, an electrochemical model is used to link the liquid-phase kinetic parameters (ionic conductivity (k₀) and liquid-phase diffusion coefficient), as corrected by the effective proportion of lithium-ion flux f_eff, to polarization and lithium-plating behavior, and the maximum current density without lithium plating under various fabrication conditions is finally determined. Results show that small-particle electrodes exhibit superior rate capability at moderate compaction levels, but suffer from rapidly increasing tortuosity and reduced transport efficiency under high compaction and large thickness. Moreover, a double-layer gradient electrode design effectively integrates the advantages of both large- and small-particle architectures, enabling high-rate operation without lithium plating. The double-layer gradient electrode (ρ = 1.6 g/cm³) exhibited ~50% higher performance at 1.5 C compared to the small-particle anode and enabled 2 C charging without lithium plating. This study offers a robust structural design strategy for optimizing thick-electrode architectures toward high-energy, fast-charging LIBs. Full article

The promising potential of porous metallic materials for railway applications (e.g., conductive materials, materials for braking systems) is due to their unique combination of low density, high specific surface area, and high energy absorption capabilities. Porous multi-phase silicide coatings (FeSi, Si₂CN₄) provide a synergistic effect, doubling surface hardness and establishing a stable diffusion barrier. The article proposes a comprehensive approach to replacing materials for critical railway transport components, involving the development of a base material and a barrier coating. The use of widely available induction-melting components to produce a base material with superior mechanical properties is demonstrated. The material exhibits high static strength and hardness while maintaining acceptable impact toughness and ductility. To enhance wear, corrosion, and scale resistance, technology for forming a barrier layer via silicide coatings is proposed. The coating formation technology enables the regulation of porosity through the formation of nitrogen-containing phases. It is shown that pores can serve as “containers” for fillers that impart functional properties to the coatings (e.g., adjusting the friction coefficient or electrical conductivity). The new base material–barrier coating system can serve as a foundation for the sustainable production of critical rolling stock parts and other devices for railway transportation systems. Full article

High-liquid-limit clay exhibits pronounced water sensitivity due to the strong electrostatic repulsion and weak interparticle bonding within its microstructure, which often limits its direct engineering uses and complicates the reuse of excavated clayey soils generated during the construction of transportation infrastructure. In this study, inorganic salts (KCl, CaCl₂ and FeCl₃) and carboxyl-containing polymers (PAAS, HPMA and CMC) were screened to construct organic–inorganic composite stabilization systems. Based on the screening results, an organic–inorganic composite system composed of CaCl₂ and sodium polyacrylate (PAAS) was developed to regulate interfacial interactions and induce microstructural reconstruction in clay. The synergistic mechanisms governing particle aggregation and dispersion were systematically investigated through Atterberg limit tests, zeta potential measurements, DLVO theoretical calculations, particle size analysis, scanning electron microscopy (SEM) and immersion disintegration experiments, combined with multivariate statistical modeling. Among the tested salt–polymer formulations, a composite system with 2% CaCl₂ and 0.1% PAAS showed the most favorable overall performance, achieving an optimal balance between electrostatic compression and steric stabilization, leading to enhanced structural integrity and delayed water-induced disintegration. Ca²⁺ ions compress the diffuse double layer and promote particle flocculation, whereas adsorbed PAAS chains introduce steric hindrance and interfacial modification. Their synergistic interaction reconstructs the pore–aggregate framework and regulates the interparticle potential energy landscape. DLVO analysis indicates that the optimized system attains a moderate critical interaction distance (h_c = 7.31 nm) and primary minimum depth (DPM = −2.72 × 10⁻¹⁶ J), reflecting a balanced interfacial bonding state. Multivariate statistical analyses further reveal a dual control pathway, in which consistency primarily governs disintegration duration, with additional contributions from surface electrochemical properties, while surface properties, soil structure and consistency collectively influence disintegration initiation. These findings elucidate the interfacial regulation and structural evolution mechanisms in organic–inorganic composite systems and provide insights into the design of composite modifiers for water-sensitive particulate materials, particularly for the resource reuse of high-liquid-limit clay excavated during the construction of transportation infrastructure and related geotechnical engineering applications. Full article

Vacancy-ordered double-perovskite Cs₂SnI₆ is known to be a good candidate for perovskite photovoltaics, as it is a light harvesting material which has potential both as an individual compound and as a component of a composite material. The compound is interesting due to being free of atom sites in B cationic positions, making the lattice “breathable” and giving it optoelectronic characteristics that vary with dopants. Here, antimony was examined as a possible heterovalent dopant with an ionic radius larger than that of Sn⁴⁺. In practice, it has been found that most of the materials are composites of Cs₂SnI₆ and Cs₃Sb₂I₉ phases. In the CsI–SnI₄–SbI₃ phase triangle, the melt crystallization process produced a layered (111)-oriented microstructure of crystallites with an increasing percentage of antimony. Two-dimensional perovskite materials look more promising in the decomposition of a solid solution to Cs₂SnI₆ and Cs₃Sb₂I₉ phases than in heterophase nucleation. The observed effect of (111)-oriented growth could be translated to other inorganic halides to form new oriented films or single crystals of perovskite materials. Diffuse reflectance spectroscopy showed an additional absorption shoulder in the NIR region for all groups of compounds, most likely induced by point defects in I sublattices of Cs₂SnI₆. Expanding the Cs₂SnI₆ absorption range to the NIR region could lead to new perspectives for its application. Full article

Geopolymers have attracted increasing attention as sustainable binders, but their long-term durability in chloride-rich environments remains a critical concern. To elucidate the mechanistic role of calcined layered double hydroxides (CLDHs) in regulating the mechanical properties and chloride diffusion behavior of geopolymers, geopolymer pastes containing different CLDH contents were prepared. The compressive strength and chloride diffusion coefficient were determined, and the underlying mechanism was analyzed from the perspectives of geopolymerization degree, gel structure development, and pore structure evolution. The results indicate that the incorporation of CLDHs can promote geopolymerization, which may be associated with a nano-seeding effect, increasing the amount and degree of polymerization of the gel phases, refining the pore structure, and reducing pore connectivity. As a result, the compressive strength increases from 38.1 MPa to 49.2 MPa, while the chloride diffusion coefficient decreases by approximately 31.7% when the CLDH content reaches 6 wt.%. However, when the CLDH content exceeds this level, particle agglomeration limits effective gel growth, leading to microstructural deterioration and a weakened regulating effect. Full article

Background: Nanoporous anodic alumina (NAA) has emerged as a promising platform for localized drug delivery in biomedical implants owing to its tunable nanoscale pore structure and biocompatibility. However, achieving the desired pore characteristics currently relies on time-consuming trial-and-error adjustments of anodization parameters. Methods: We developed a comprehensive data-driven machine learning framework using a feed-forward artificial neural network (ANN) with three hidden layers (64-32-16 neurons) trained on 77 samples from a compiled dataset of 99 anodization experiments spanning 1995–2025. The model predicts the NAA pore diameter based on anodization conditions (electrolyte type, concentration, voltage, temperature, and time). Results: The ANN achieved R² = 0.803, root mean square error (RMSE) = 25.83 nm, and mean absolute error (MAE) = 17.05 nm on training data; however, 5-fold cross-validation revealed moderate generalization (CV R² = 0.471 ± 0.078). Multiple linear regression showed comparable training performance (R² = 0.804) but superior cross-validation (CV R² = 0.729 ± 0.083). Feature importance analysis identified anodization voltage (29.15% ANN importance) and electrolyte type (30.23%) as the most influential factors. Coupling ANN-predicted pore dimensions with Higuchi diffusion modeling demonstrated that the pore diameter increased from 50 to 100 nm, nearly doubling the initial release rates (8 to 11 h⁻¹) and reducing the time to 50% release from 39.1 to 20.7 h. Conclusions: This data-driven approach offers a powerful tool to reduce experimental iteration and accelerate the development of advanced drug-delivery implants by enabling the rational design of NAA pore structures for optimized drug loading and release kinetics. Full article

The global energy transition and the implementation of carbon capture, utilization, and storage (CCUS) strategies require energy-efficient and scalable CO₂ separation technologies. Mixed-matrix membranes (MMMs), combining polymer matrices with functional inorganic or hybrid nanofillers, have emerged as advanced separation platforms capable of surpassing the conventional permeability–selectivity trade-off observed in neat polymer membranes. This review critically evaluates recent developments in modern hybrid membranes for CO₂ separation from synthetic and industrial gas mixtures, including CO₂/N₂ (flue gas), CO₂/CH₄ (natural gas and biogas upgrading), and syngas systems. Particular emphasis is placed on MMMs incorporating covalent organic frameworks (COFs), metal–organic frameworks (MOFs), graphene oxide (GO), MXenes, transition metal dichalcogenides (TMDs), carbon nanotubes (CNTs), g-C₃N₄, layered double hydroxides (LDH), zeolites, metal oxides, and magnetic nanoparticles. Reported performance ranges include CO₂ permeability (P_CO2) typically between 100 and 800 Barrer, CO₂/N₂ selectivity up to 319, and CO₂/CH₄ selectivity up to 249, depending on filler chemistry, loading, and interfacial compatibility. The mechanisms governing gas transport—molecular sieving, selective adsorption, facilitated transport, and diffusion-pathway engineering—are systematically discussed. Key challenges addressed include filler dispersion, polymer–filler interfacial defects, physical aging, moisture sensitivity, oxidation (particularly in MXenes), and scalability toward industrial membrane modules. Future perspectives focus on sub-nanometer pore engineering, surface functionalization to enhance CO₂ affinity, controlled alignment of 2D nanosheets to promote directional transport, multifunctional core–shell and hollow structures, and the integration of computational modeling and machine learning for accelerated material design. Modern hybrid MMMs are identified as strategically important materials enabling high-efficiency CO₂ separation processes aligned with decarbonization and energy transition objectives. Full article

We present the simulation-guided design and experimental demonstration of high-speed 940 nm vertical-cavity surface-emitting lasers (VCSELs). Utilizing established device optimization principles, a simulation study was conducted focusing on the number of oxide layers and the aperture size, which predicted a maximum modulation bandwidth of over 35 GHz. To validate the simulation, a device with a 4-μm double-oxide aperture was fabricated and characterized. Additionally, a Zn-diffusion process was incorporated during fabrication to reduce p-DBR resistance and suppress higher-order transverse modes. The fabricated device achieved an experimental modulation bandwidth of 34 GHz and demonstrated successful 100 Gbit/s PAM-4 data transmission. The close agreement between the simulated and measured performance highlights the successful practical integration of these techniques for developing high-speed optical interconnects. Full article

We developed an arbitrary Lagrangian–Eulerian (ALE)-based multiphysics model for evaporation from a contact-line-pinned sessile drop of neat water subject to a vertically oriented sinusoidal alternating current (AC) electric field applied across parallel-plate electrodes. The framework fully couples electrostatics, incompressible flow, heat transfer with evaporative cooling, and transient vapour transport in air, and includes an instantaneous, voltage-controlled electrowetting contact-angle response under constant-contact-radius conditions. Validation against published data shows that the model captures both pinned-droplet evaporation and electrically induced deformation. Because Maxwell traction scales with the squared electric-field magnitude, droplet height and contact angle exhibit a robust 2:1 frequency-doubled response, producing two peak–trough events per voltage period. The resulting periodic deformation drives oscillatory interfacial shear and internal recirculation, yielding a synchronous double-peaked evaporative-flux waveform. Gas-side analysis quantifies a time-varying diffusion-layer thickness via a characteristic diffusion length; two thinning events per period coincide with flux maxima, indicating that AC enhancement is dominated by periodic compression of the vapour boundary layer and reduced gas-side mass-transfer resistance. Increasing voltage amplitude (0–60 kV) strongly accelerates volume loss, while frequency has a secondary effect: the cycle-averaged flux rises from 1 to 10 Hz but decreases slightly at 20 Hz due to phase lag and weaker boundary-layer modulation. Full article

Marine clay serves as the natural foundation for various types of offshore and marine engineering structures and therefore plays a critical role in marine engineering practice. Consequently, a thorough understanding of the microstructural characteristics of marine clay is of great importance. In this study, two types of artificial marine clays with high and low clay contents were selected. Environmental scanning electron microscopy (ESEM), zeta potential measurements, and dynamic light scattering (DLS) tests were conducted to investigate the microstructure, surface electrical potential, and aggregation behavior of marine clay. The results revealed that the high-clay-content sample exhibited more compact particle connections, while the low-clay-content sample displayed a relatively loose structure. The addition of salt altered the particle distribution within the soil, increasing the aggregation of fine clay particles, which in turn compressed the diffuse double layer between particles. This caused changes in the surface electrokinetic potential of clay mineral particles and enhanced the stability of the soil samples. DLS tests on the high-clay-content sample showed that the aggregation state of clay particles was highly sensitive to salinity, with particle size initially increasing and then decreasing as salinity increased. Full article

This review comprehensively examines the influence of clay plasticity on thermally induced volume changes in saturated clays, which is a critical factor in the design and performance of energy geostructures, nuclear waste repositories, and thermal ground improvement systems. This study synthesises experimental and theoretical findings, demonstrating that the plasticity index and mineralogical composition significantly govern the magnitude and nature of volume change during heating and cooling cycles, with stress history playing a pivotal role. Unlike previous review papers that primarily discuss general thermo-mechanical behaviour or constitutive modelling frameworks, this review explicitly focuses on plasticity as the central unifying parameter influencing thermally induced volume change. It further provides a structured synthesis that integrates plasticity, stress history, and microstructural mechanisms. Normally consolidated clays exhibit irreversible thermal contraction, which intensifies with plasticity, whereas highly overconsolidated clays typically exhibit reversible expansion. Lightly overconsolidated clays exhibit transitional behaviour characterised by initial expansion followed by collapse. This review links these macroscopic responses to microstructural mechanisms, including interparticle physicochemical forces, diffuse double-layer dynamics, and bound water behaviour, highlighting the limitations of idealised electrochemical models and emphasising the importance of micromechanical processes. It further explores how plasticity modulates temperature-dependent reductions in preconsolidation pressure, thermal softening, cyclic thermal deformation, and time-dependent thermal creep, with higher plasticity clays showing greater sensitivity and longer stabilisation periods. The findings underscore the necessity of incorporating plasticity and stress history into constitutive models to accurately predict the thermo-mechanical behaviour of clays under service conditions, with significant implications for the long-term reliability of thermal geotechnical applications. Full article

As a response to aging of cultured urease-producing microorganisms, the blending method was examined to obtain the required carbonate production amount using the apparent viability (Rcv) based on previous research. As a result, a significantly higher carbonate content than the amount of CaCl₂ 2H₂O used was produced. Since this trend has been obtained in previous studies, it was judged that carbonate hydrate was formed. As a next step, a penetration test of soil–biocement–liquid (BCS) was conducted to investigate the properties and behavior of the BCS system, taking into account the microscopic properties of the BCS response. The depth distribution of carbonate content (C) was measured by the acid dissolution method of soil sampled from the specimen. It was assumed that the C-profile was formed by adsorption based on the diffuse double layer of microorganisms. It was shown that the amount of precursor-carbonate (precursor CPR), the optical density (OD) of viable bacteria, and the physical amount of soil adsorbed at that position can be estimated from C obtained at the various depths. In addition, the previously obtained formulas among CPR, viable OD, and Rcv shown are briefly explained in this paper. Full article