Search Results (455)

Electrochemical impedance spectroscopy (EIS) is a powerful, non-destructive tool for evaluating ion-selective electrode (ISE) membrane condition. This work investigated EIS for identifying degradation mechanisms in all-solid-state Pb²⁺-selective electrodes. Graphene-containing PVC membranes deposited on glassy carbon electrodes were exposed to synthetic urine, river water, and seawater (24 h and 1 week) and to mechanical damage (cutting, needle puncture, or both). Degradation was assessed using EIS, potentiometric measurements, contact-angle analysis, profilometry, and SEM. River water and urine exposure decreased hydrophobicity, increased roughness, and produced fouling deposits. Seawater caused only minor morphological and wettability changes, though impedance data showed increased membrane hydration due to high ionic strength. Mechanical damage substantially disrupted membrane integrity, causing pronounced impedance changes, increased potential drift, and reduced analytical performance. Fouling and mechanical damage produced distinct electrochemical signatures: fouling mainly affected surface properties, while mechanical damage altered the membrane–transducer interface, increasing capacitance and reducing resistance. Notably, needle-punctured electrodes retained a near-Nernstian response despite clear impedance changes and reduced long-term stability, showing that EIS detects defects invisible to conventional calibration. These results confirm EIS as a sensitive method for distinguishing fouling from physical damage, useful for early degradation detection and lifetime monitoring of all-solid-state ISEs. Full article

Stainless-steel bipolar plates (BPPs) are attractive for proton exchange membrane water electrolysis (PEMWE) due to their low cost and manufacturability, yet their use is limited by severe corrosion. Despite the advantages of plasma-enhanced atomic layer deposition (PEALD) in producing dense films, ion bombardment may induce surface damage and increase roughness. This paper describes a cross-flow PEALD strategy with a remote plasma source to deposit metallic tantalum (Ta) coatings on stainless steel. In a cross-flow reactor, plasma species reach the substrate primarily through diffusion across the boundary layer of the gas flow, providing a gentler plasma–surface interaction and enabling the formation of dense, smooth Ta coatings. The roughness of the Ta films is markedly reduced from 1.45 nm to 0.24 nm, which is favorable for interfacial electrical contact. The process exhibits self-limiting growth with a linear growth rate of ~0.49 Å cycle⁻¹. In a simulated PEMWE environment, Ta-coated stainless steel shows improved corrosion resistance, with the corrosion potential increasing from −0.27 to 0.07 V vs. Ag/AgCl (pH 0.3) and the corrosion current density decreasing to 2.05 × 10⁻⁷ A cm⁻². Overall, cross-flow PEALD enables high-quality metallic Ta coatings that enhance corrosion protection and interfacial electrical performance for BPPs. Full article

Asymmetric SiC membranes with surface pore sizes ranging from 0.12 to 0.31 μm at a constant open porosity of approximately 42% were fabricated by dip-coating SiC support followed by sintering from 1700 to 2000 °C. The effect of membrane structural constants (hydraulic resistance (k₁), pore size exponent (k₂), and shape factor (k₃)) on PWP were evaluated by comparing the symmetric and asymmetric structures. In addition, the experimentally determined values of PWP were quantitatively analyzed by comparing with theoretically predicted values obtained using the Kozeny–Carman (K–C) and Hagen–Poiseuille (H–P) models. Despite having a smaller pore size, the asymmetric membranes exhibited high PWP (1257-3883 LMH) due to decreased flow resistance (low k₁), enhanced pore size effect (high k₂), and improved flow network (high k₃) as compared to symmetric membranes. The hydrophilicity of the prepared membranes improved remarkably, with increasing average surface roughness (102.3 nm to 161.0 nm) due to an increase in pore size, which also caused a decrease in water contact angle (WCA) from approximately 27.44° to 21.67° with increasing sintering temperature (1700–2000 °C). Furthermore, the prepared membrane separation performance was found to be affected by its pore size, and the 1900 °C sintered SiC membrane showed optimal gradient profile and pore structure, demonstrating its practical reusability and scalability for O/W wastewater treatment. Full article

To tackle the environmental challenges associated with industrial oily wastewater discharges and recurrent marine oil spill incidents, developing high-efficiency oil–water separation technologies represents a pressing environmental challenge. This research presents a novel design approach comprising the deposition of a stable SiO₂ anchoring layer followed by the fabrication of a PDA/CS crosslinked coating, thereby achieving successful construction of a superhydrophilic/underwater superoleophobic (SH/UWSO) coating on stainless steel meshes (SSM). In the first step, SiO₂ microspheres were deposited via vapor deposition to create a micro-rough surface architecture. Subsequently, a dopamine/chitosan (DA/CS) reaction solution was introduced to form a Polydopamine/chitosan (PDA/CS) coating, yielding a SiO₂@PDA/CS-SSM separation membrane. The resulting membrane exhibited separation efficiencies surpassing 99% for various oil–water mixtures, achieving a flux of 1.24 × 10⁵ L·m⁻²·h⁻¹ in petroleum ether systems. Notably, the membrane maintained high efficiency and structural stability even after 25 separation cycles, immersion in strong acid and base solutions for 72 h, and 100 abrasion tests. The rational design of the anchoring and crosslinking layers endows SiO₂@PDA/CS-SSM with high efficiency and stability, making it an effective oil–water separation material. Full article

The sustainable recovery of high-value metals from wastewater has garnered significant attention in light of the circular economy and environmental preservation. Because of its appealing characteristics, membrane separation technology is essential for the sustainable and effective recovery of valuable metals from wastewater, in contrast to conventional methods, which are chemical- or energy-intensive. In this study, a rational design approach was utilized to synthesize a metal–organic framework (MOF) using a deep eutectic solvent (DES) as a mediating medium to control the reaction of framework formation and particle properties. While DESs have been widely used for the physical modification of materials, their role as a chemically modifying medium during MOF synthesis for structural tailoring remains less explored. This synthesized MOF (DM-Zn-PDC@MOF) was further introduced as filler in polysulfone (PSf)-based mixed matrix membranes (MMMs). The performance of DM-Zn-PDC@MOF within the polymer matrix was examined. Several characterization techniques were used to thoroughly analyze the morphological, chemical, and physical characteristics of the MMMs and DM-Zn-PDC@MOF. The addition of the filler material significantly enhanced the membrane characteristics, including pure water flux, hydrophilicity, porosity, surface roughness, pore size, and heavy metal resource recovery in comparison with the pristine membrane. Stable incorporation of the filler within the membrane matrix was indicated by much less filler leaching (<5%) at all concentrations. With DM-Zn-PDC@MOF loading, the pure water flux increasedmore than nine times from 102.8 L/m²h (M-0) to 971.5 L/m²h (M-4). The functionalized membranes showed better flux retention in high-value heavy metal resource recovery using simulated wastewater: 871.8 L/m²h when filtering a Pb(II) ion solution (compared to M-0 with flux 120.6 L/m²h) and 526.8 L/m²h when filtering a Cr(III) ion solution (compared to M-0 with flux 97.1 L/m²h). These values represented approximately 7-fold and 5-fold improvements, respectively. Overall, Pb⁺² > Cr⁺³, but the rejection of Cr(III) ions was also improved, when compared with M-0. The high flux of the membrane makes it easier to process large volumes and concentrate metals in the retentate, turning diluted contaminated streams into a concentrated feedstock for subsequent recovery procedures. Full article

Buildings account for a significant share of global energy consumption and carbon emissions, creating an urgent need for advanced energy retrofit technologies. This review critically examines the role of plasma-modified textile polymer materials in improving the energy efficiency and durability of building retrofit systems. Various textile polymers, including polyester (polyethylene terephthalate, PET), polypropylene (PP), polytetrafluoroethylene (PTFE), polyamide (PA), and fiber-reinforced composites, are evaluated in relation to plasma surface engineering approaches, including atmospheric plasma, dielectric barrier discharge (DBD), and plasma jet treatment. Reported studies demonstrate that plasma treatment significantly alters surface morphology and chemistry, resulting in increased surface roughness, enhanced wettability, improved coating adhesion, and superior hydrophobic behavior. Water contact angles increased from approximately 70° to 145° depending on polymer type and plasma conditions, while reflective coating performance improved with solar reflectance enhancements of approximately 10–15%. Plasma-treated reflective roofing and shading textiles also showed reductions in building cooling energy demand of approximately 18–25% and roof temperature decreases of 10–15 °C. Furthermore, plasma-induced surface activation improved durability, ultraviolet (UV) resistance, and weather stability of textile membranes used in facade and roofing applications. The review also discusses industrial challenges related to scalability, plasma aging effects, energy consumption, and long-term performance. Plasma-modified systems demonstrate strong potential for multifunctional, lightweight, and sustainable building envelope technologies for future energy-efficient construction. Full article

This study presents a discrete–continuous flux-guided shape-refinement framework for freeform shell geometries under self-weight. The method evaluates the directional relation between a prescribed support-directed transmission field and the shell surface normal, identifies locally underperforming regions, applies top-down geometric updates, and reconstructs a continuous surface at each step. It is intended as a transparent intermediate stage between intuitive freeform design and high-fidelity structural verification. The framework is demonstrated on nine shell cases with different geometries, support conditions, height ranges, and surface irregularities. Across all the cases, the results show reduced normal-component misalignment and increased tangential alignment relative to the prescribed transmission field. A representative finite-element comparison provides case-specific supporting evidence that under a linear-elastic gravity-load model the refined geometry can reduce deformation and stress levels over large surface regions; however, it does not prove general structural optimality or fully membrane-dominated behavior. Geometric roughness remains a key limitation requiring explicit regularization in future work. The approach is positioned as a lightweight geometric pre-optimization tool for conceptual shell design, rather than as a substitute for equilibrium-based form-finding or detailed structural optimization. Full article

The Ib-M1 peptide exhibits bactericidal activity against Escherichia coli O157:H7 and low toxicity in mammalian cells. The present study aimed to evaluate the effect of Ib-M1 on E. coli O157:H7 membrane permeabilization. For this purpose, the minimum inhibitory concentrations of Ib-M1 for E. coli O157:H7 and ML35 were measured. The permeability of the E. coli outer and inner membranes was determined by measuring N-phenyl-1-naphthylamine and O-nitrophenyl-β-galactosidase hydrolysis, respectively after bacterial exposure to antimicrobial peptides and control antibiotics. Morphological changes in antimicrobial-exposed E. coli O157:H7 were evaluated by scanning electron microscopy following treatment with antimicrobial peptides. Ib-M1 expressed activity against E. coli O157:H7 and ML35 at minimal inhibitory concentrations (MIC) of 2.9 ± 1.7 and 6.3 ± 0 μM, respectively. The peptide induced permeabilization of the outer membrane of E. coli O157:H7 at all concentrations evaluated and permeabilization of the inner membrane after 50 min at concentrations between 1× MIC and 8× MIC. The morphological changes induced by Ib-M1 led to significant alterations in bacterial shape including collapsed cells and pronounced surface roughness and invaginations. In conclusion, physiological and morphological evidence indicates that the Ib-M1 antimicrobial effect against E. coli O157:H7 is mediated by its permeabilizing action on the outer and inner bacterial membranes. Full article

Proton exchange membrane fuel cells (PEMFCs) exhibit high energy efficiency and rapid load response, but challenges are faced in membrane fabrication, including the need for renewable resources and cost-effective, non-toxic solvents. This study analyzes the morphological and structural properties of perfluorosulfonic acid (PFSA) ionomer membranes, FS-930 and F-14100, after the dissolution of membranes via ratios of 50:50, 80:20, and 20:80 by volume of dimethyl sulfoxide (DMSO) and water. Bode plot analysis indicates that membranes rich in DMSO show lower frequency phase angle peaks, suggesting better segmental motion and ionic conductivity. Additionally, higher DMSO content correlates with broader FTIR peaks, reflecting enhanced solute–solvent interactions. The untreated FS-930 membrane demonstrates significant intensity peaks linked to semi-crystalline domains, indicating strong baseline conductivity. SEM analysis revealed surface roughness variations in FS-930 linked to different water-to-DMSO volume ratios. DMSO-rich mixtures produced dense, hydrophobic PFSA membrane structures, whereas water-rich mixtures increased water uptake and ionic conductivity. Fumapem F-14100 showed superior hydration and proton conductivity compared to FS-930 because it contains more sulfonic acid groups. These findings are critical to understanding how membrane properties relate to solvent composition, aiding in the optimization of membrane fabrication for better performance and durability in fuel cells. Full article

Forward osmosis (FO) membranes have garnered widespread research interest in water treatment, yet their permeability–selectivity trade-off, internal concentration polarization, and membrane fouling remain critical challenges. Herein, a chitooligosaccharide/polydopamine (COS/PDA) co-deposition strategy was proposed to modify polyethersulfone (PES) substrates for constructing high-performance thin-film composite (TFC) FO membranes. COS suppressed excessive PDA aggregation, reduced substrate roughness, and improved substrate hydrophilicity. This substrate modification regulated interfacial polymerization by increasing the adsorption capacity for m-phenylenediamine (MPD) while slowing its diffusion rate, thereby forming thinner, smoother, and more densely crosslinked polyamide (PA) layers. The optimized C₄P₁-TFC membrane delivered water fluxes of 42.2 and 23.5 L m⁻² h⁻¹ in pressure-retarded osmosis (PRO) and FO modes, respectively, representing 43.1% and 40.2% improvements over the pristine membrane. Its specific salt flux decreased to 0.07 and 0.15 g L⁻¹ in the two modes, respectively, suggesting enhanced selectivity. Meanwhile, the C₄P₁-TFC membrane showed antibacterial rates of 85.7% against Escherichia coli and 86.9% against Staphylococcus aureus, together with improved antifouling performance against bovine serum albumin and lysozyme. This work presents a simple and effective co-deposition approach for simultaneously improving the separation, antibacterial, and antifouling performance of TFC FO membranes, showing promising potential for practical applications. Full article

Nanotextured thin film metallic glasses (TFMGs) have emerged as promising antimicrobial coatings for biomedical applications; however, systematic comparisons across compositionally distinct Ti- and Zr-based systems, as well as their early-stage bactericidal mechanisms, remain limited. Here, we show, for the first time, a comparative, compositionally resolved correlation linking alloy chemistry, nanotexture, and bactericidal mechanisms across polymorphic TFMGs. Three co-sputtered biocompatible coatings (Ti₄₇Fe₄₁Cu₁₂, Zr₇₁Fe₃Al₂₆, and Zr₅₈W₃₁Cu₁₁) were deposited on medical-grade titanium and stainless steel (SS316L) via magnetron co-sputtering, producing uniform amorphous films (190–298 nm) with nanoscale roughness of 1.6 ± 0.05 to 8.1 ± 0.05 nm. Surface wettability spanned hydrophilic (71.1 ± 5.6°) to hydrophobic (106.5 ± 3.5°), modulating bacterial interactions. Antimicrobial performance against Pseudomonas aeruginosa was evaluated using live/dead fluorescence imaging, quantitative image analysis, and electron microscopy after 2–4 h incubation. All coatings reduced bacterial adhesion and viability relative to bare substrates, with Zr₅₈W₃₁Cu₁₁ achieving >60% reduction in surface-associated bacterial coverage. Time-resolved analysis revealed a rapid transition to predominantly non-viable populations on coated surfaces, in contrast to sustained viability on controls. Mechanistically, bactericidal activity arises from the synergistic coupling of nanotopography-induced membrane stress, wettability-governed adhesion energetics, and in situ formation of CuO, Fe₂O₃, WO₃, and ZrO₂ oxides that promote electrostatic interactions and proposed reactive oxygen species generation, driving oxidative membrane damage. These results establish a scalable design framework for TFMGs, while highlighting the need for long-term biofilm and electrochemical validation. Full article

Low-molecular-weight chitosan derivatives emerged as promising plant growth biostimulants due to their favorable properties, such as biocompatibility, antibacterial and antifungal activity, enhancement of stress resistance, and yield improvement. In the present study, we evaluated the effect of pea seed priming with two types of chitooligosaccarides (aminochitooligosaccaride and chitooligosaccaride hydrochloride) applied at concentrations of 100 and 500 mg/L under non-stress conditions and 50 mM chronic NaCl stress. We characterized the seed surface topology by atomic force microscopy, the germination process by evaluation of seed germinability and synchrony, root emergence, seed imbibition capacity and ion leakage. Early plant growth and physiological performance were further evaluated in 14-day-old seedlings by measuring leaf water potential, Na⁺ accumulation in roots and leaves, photosystem II activity, leaf pigment content, and membrane stability. The results revealed changes in seed coat topology, i.e., higher surface roughness in 100 and 500 mg/L chitooligosaccaride hydrochloride and 500 mg/L aminochitooligosaccaride primed variants. Concentration-dependent effects of the two chitooligosaccarides under both non-stress and salt stress conditions were evident in 14-day-old seedlings. Under chronic salt stress, seed priming with 100 mg/L chitooligosaccharide hydrochloride and 500 mg/L aminochitooligosaccharide produced the most pronounced improvements in the primary photochemical reactions of photosynthesis, particularly the performance index on an absorption basis and the total performance index. Moreover, the investigated chitooligosaccharide, particularly chitooligosaccaride hydrochloride, preserved membrane integrity and maintained flavonol and anthocyanin levels, indicating a strong protective effect against salt stress. Overall, the data indicate beneficial effects on pea physiological status following seed priming with chitooligosaccarides under chronic salt stress conditions. This highlights the approach as a promising strategy for enhancing plant resilience in challenging environments, and it is worth further investigation and verification at the whole-plant level. Full article

Proton exchange membranes (PEMs) are essential for PEM fuel cells, with proton conductivity arising from the hydration-induced ionic channel network. PEM performance can be enhanced through pretreatments, such as annealing, which reconstruct the ionic channels. This study investigates the ionic channel network variation in Nafion 212 under continuous annealing at 90 °C using current-sensing atomic force microscopy (CSAFM). A nanoscale PEM fuel cell was formed with a Pt-coated CSAFM tip and Pt-coated Nafion surface. Topography and surface roughness analyses revealed geometrical changes from annealing. Current-sensing images and histograms qualitatively assessed local conductance and ionic channel distribution. The ionic channel network density was quantitatively evaluated using the number of protons moving through the ionic channel network (NPMI), derived from CSAFM and electrodynamics principles. NPMI directly reflects ionic channel density. From the unannealed state to 60 h, NPMI increased linearly at 1 × 10⁴ h⁻¹, indicating enhanced channel formation. Beyond 60 h, NPMI decreased linearly at 1.9 × 10⁵ h⁻¹, reflecting progressive network degradation. As the ionic channel network increases, the number of protons reaching the membrane surface also increases, whereas in the opposite case it decreases. Thus, NPMI becomes evaluation criterion for ionic channel network density. These findings systematically link nanoscale structural changes to ionic channel reconstruction and proton transport in Nafion 212, providing insight into PEM performance evolution under thermal treatment. Full article

In medicine and dentistry, bone-loss treatment often uses hydroxyapatite combined with collagen membranes. The biocompatibility of these biomaterials depends on their composition and physical/mechanical properties. In this study, a graft composed of synthetic hydroxyapatite nanoparticle (Blue Bone^®) and a bovine type I collagen membrane (Green Membrane Perio^®) was developed compared with commercial Bio-Oss^® graft and Mucograft^® membrane. The materials were characterized by roughness, wettability, tensile testing, DSC, SEM, and TEM. In vivo, temporoparietal bone defects were created in 40 Wistar rats divided into five groups (n = 8): sham (no biomaterial); Bio-Oss^®; Bio-Oss^® + Mucograft^®; Blue-Bone^®; and Blue-Bone^® + Green Membrane Perio^®. Immunohistochemistry showed Green Membrane Perio^® was made of thin, well-organized type I collagen fibers and was free of contaminants. Immunohistochemistry, histology, and immunohistochemical analyses indicated that Blue Bone^® and Green Membrane Perio^® were biocompatible and supported tissue regeneration. The Blue Bone^® groups demonstrated higher collagen content than the Bio-Oss^® + Mucograft^® group. Quantitative and qualitative outcomes included morphological, thermal, mechanical, and surface property measurements, as well as cellular compatibility testing. The results showed comparable wettability and surface roughness, adequate membrane tensile strength, osteoconductive nanoparticle morphology, no adverse inflammatory reactions, and similar new bone formation metrics compared with controls. In conclusion, the combination of synthetic hydroxyapatite nanoparticles (Blue Bone^®) and a bovine type I collagen membrane (Green Membrane Perio^®) showed good performance when compared to established products and was considered safe and biocompatible for bone repair applications. Full article

This study investigates the development of mixed matrix membranes based on polyethersulfone incorporated with attapulgite for gas separation applications, addressing the existing gap regarding the use of this mineral in dense membranes obtained exclusively by solvent evaporation and its combined effects on microstructure and transport. The membranes were prepared by phase inversion via solvent evaporation, using solvent/polymer ratios of 75/25 and 80/20 and a thickness of 0.25 mm. The solutions were evaluated in terms of viscosity, and the membranes were characterized by structural techniques such as X-ray diffraction (XRD), atomic force microscope (AFM), contact angle, mechanical properties (tensile testing), and water vapor permeation. The results showed that attapulgite incorporation promoted a reduction in surface roughness (up to ~40%) and a decrease in contact angle (from ~89° to ~68°), indicating increased hydrophilicity. In addition, water vapor permeability was influenced in a non-linear manner, with optimized performance observed at 3 wt% filler loading. Solution viscosities remained within ranges suitable for processing. Structural analyses indicated compatibility between the phases, while morphology changes dependent on filler content were decisive for transport behavior. It is concluded that attapulgite is a promising additive for fine-tuning membrane properties, enabling optimization of the sorption–diffusion balance and improvement of membrane performance in separation applications. Full article