Search Results (642)

The build-up of a fouling layer on the membrane surface is believed to deteriorate flux and salt rejection by hindering back-diffusion of rejected salts, a phenomenon called cake-enhanced concentration polarization (CECP). Nevertheless, CECP effects have not been linked to the salt rejection properties of the membrane. Furthermore, the decline in salt rejection during fouling has not been related to the decreasing flux, to elucidate the effects of flux on solution rejection as described by the solution-diffusion (SD) model. Therefore, this work examined whether CECP is substantial in membranes with poor salt-rejection properties. Fouling was performed using sodium alginate, Al₂O₃, latex, and SiO₂. The effects of fouling on salt rejection were studied using two nanofiltration (NF) membranes, namely NF270 membrane (46% NaCl rejection) and NF90 membrane (>97% NaCl rejection). The measured flux and salt rejection profiles were compared to those predicted by the CECP and SD models. Overall, the flux declined more (30–60%) for the NF90 membrane (contact angle: 50 ± 3°) compared to the NF270 membrane (10–55%, contact angle: 39 ± 2°) under similar hydrodynamic conditions. Moreover, fouling had more effects on NaCl rejection for the NF90 membrane (2–45% decline) compared to the NF270 membrane (10–30% decline). The decrease in NaCl rejection for the NF90 membrane was ascribed to CECP effects and declining flux. Contrary, CECP effects were less important for the NF270 membrane, and rejection declined due to reduction in flux as predicted by the SD model, indicating that CECP may not be predominant in membranes that poorly reject salts. Full article

Current treatment methods for desulfurization wastewater in the ship exhaust gas cleaning (EGC) system face several problems, including process complexity, unstable performance, large spatial requirements, and high energy consumption. This study investigates rotating dynamic filtration (RDF) as an efficient treatment approach through experimental testing, theoretical analysis, and pilot-scale validation. Flux increases with temperature and pressure but decreases with feed concentration, remaining unaffected by circulation flow. For a small membrane (152 mm), flux consistently increases with rotational speed across all pressures. For a large membrane (374 mm), flux increases with rotational speed at 300 kPa but firstly increases and then decreases at 100 kPa. Filtrate turbidity in all experiments complies with regulatory standards. Due to the unique hydrodynamic characteristics of RDF, back pressure reduces the effective transmembrane pressure, whereas shear force mitigates concentration polarization and cake layer formation. Separation performance is governed by the balance between these two forces. The specific energy consumption of RDF is only 10–30% that of cross-flow filtration (CFF). Under optimized pilot-scale conditions, the wastewater was concentrated 30-fold, with filtrate turbidity consistently below 2 NTU, outperforming CFF. Moreover, continuous operation proves more suitable for marine environments. Full article

Background/Objectives: The work presented herein focused on the development and characterization of a transdermal caffeine platform fabricated from ultrathin micro- and submicron fibers produced via electrospinning. Methods: The formulations incorporated caffeine encapsulated in a polyethylene oxide (PEO) matrix, combined with various permeation enhancers. A backing layer made of annealed electrospun polycaprolactone (PCL) facilitated the lamination of the two layers to form the final multilayer patch. Comprehensive characterization was conducted, utilizing scanning electron microscopy (SEM) to assess the fiber morphology, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) for chemical detection and to assess the stability of the caffeine, and differential scanning calorimetry (DSC) along with wide-angle X-ray scattering (WAXS) to analyze the physical state of the caffeine within the fibers of the active layer. Additionally, Franz cell permeation studies were performed using both synthetic membranes (Strat-M) and ex vivo human stratum corneum (SC) to evaluate and model the permeation kinetics. Results: These experiments demonstrated the significant role of enhancers in modulating the caffeine permeation rates provided by the patch, achieving permeation rates of up to 0.73 mg/cm² within 24 h. Conclusions: This work highlights the potential of using electro-hydrodynamic processing technology to develop innovative transdermal delivery systems for drugs, offering a promising strategy for enhancing efficacy and innovative therapeutic direct plasma administration. Full article

Thiophene derivatives are particularly attractive for application in drug development for their versatile pharmacological properties. We synthesized a series of four compounds with thiophene carboxamide as a scaffold. The structures were established based on HR-MS and 1D- and 2D-NMR. The purity of the compounds was established to be greater than 92% by thin-layer chromatography and NMR. The cytotoxic effects of the newly synthesized compounds were evaluated against the normal HaCaT cell line and A375, HT-29, and MCF-7 cancer cell lines. The cytotoxic assessment revealed that two compounds exhibit a significant cytotoxic effect on all cancer cell lines. To investigate their potential underlying mechanisms of action, several tests were performed: immunofluorescence imaging, caspase-3/7 assay, mitochondrial membrane potential (JC-1) assay, and 2′,7′–dichlorofluorescein diacetate (DCFDA) assay. MB-D2 proved to be the most cytotoxic and effective in terms of caspase 3/7 activation, mitochondrial depolarization and decrease in ROS production; these effects did not occur in normal HaCaT cells, revealing that MB-D2 has a high selectivity against A375 cancer cells. Full article

Tissue-engineered artificial skin has the potential to enhance wound healing without necessitating extensive surgical procedures or causing donor-site morbidity. The purpose of this study was to examine the possibility of developing tri-layered tissue-engineered full-thickness artificial skin with a basement membrane for clinical use to accelerate wound healing. We engineered full-thickness artificial skin with a basement membrane for wound healing by employing stromal vascular fraction (SVF) cells for the dermal layer and autologous keratinocytes for the epidermal layer. The fabrication of a basement membrane involved the use of 100% bovine collagen and 4% elastin produced through a low-temperature three-dimensional printer. Scaffolds for cells were printed with 100% bovine collagen. The basement membrane underwent evaluations for collagenase degradation, tensile strength, and structural characteristics using scanning electron microscopy. The final tri-layered full-thickness artificial skin included two cell scaffolds with a basement membrane between them. The basement membrane may support cellular attachment without inducing significant cytotoxic effects. This study presents a novel strategy for full-thickness artificial skin development, combining SVF and keratinocytes with an optimized collagen-elastin basement membrane. This method may overcome the significant limitations of current artificial skin, thereby contributing to the advancement of tissue-engineering in wound healing for clinical use. Full article

One of the key challenges in commercializing proton exchange membrane (PEM) electrolyzer technology is reducing the production costs while maintaining high efficiency and operational stability. Significant contributors to the overall cost of the device are the electrode catalysts with IrO₂ and Pt/C. Due to the high cost and limited availability of noble metals, there is growing interest in developing alternative, low-cost catalytic materials. In recent years, two-dimensional transition metal dichalcogenides (2D TMDCs), such as molybdenum disulfide (MoS₂) and rhenium disulfide (ReS₂), have attracted considerable attention due to their promising electrochemical properties for hydrogen evolution reactions (HERs). These materials exhibit unique properties, such as a high surface area or catalytic activity localized at the edges of the layered structure, which can be further enhanced through defect engineering or phase modulation. To increase the catalytically active surface area, the investigated materials were deposited on a carbon-based support—Vulcan XC-72R—selected for its high electrical conductivity and large specific surface area. This study investigated the physicochemical and electrochemical properties of six catalyst samples with varying MoS₂ and ReS₂ to carbon support ratios. Among the composites analyzed, the best sample on MoS₂ (containing the most carbon soot) and the best sample on ReS₂ (containing the least carbon soot) were selected. These were then used as cathode catalysts in an experimental PEM electrolyzer setup. The results confirmed satisfactory catalytic activity of the tested materials, indicating their potential as alternatives to conventional noble metal-based catalysts and providing a foundation for further research in this area. Full article

Helicobacter pylori, which colonizes the human gastric mucosa, uses a cluster of polar, sheathed flagella to swim across the mucous layer of the stomach. The function and biogenesis of the H. pylori flagellar sheath are poorly understood. Cardiolipin is a phospholipid that accumulates in regions of the membrane that have negative curvature, such as the cell pole, cell septum, and flagellar sheath. The final step in cardiolipin biosynthesis is catalyzed by cardiolipin synthase. H. pylori has at least two cardiolipin synthases, one of which is cardiolipin synthase C (ClsC). Bioinformatic analysis revealed that homologs of H. pylori ClsC are restricted to Helicobacter species that have sheathed flagella and the ClsC homologs are predicted lipoproteins. Fluorescence microscopy revealed that a ClsC super-folder green fluorescent protein localized to the cell pole and cell septum in H. pylori G27. Comparing the proteomes of isolated sheathed flagella from the H. pylori B128 wild type and a clsC::cat mutant, we identified five proteins that were absent in the mutant flagellum preparations. One of the proteins was FaaA, an autotransporter that localizes to the flagellar sheath. These findings suggest that the localization of FaaA and possibly other proteins to the flagellar sheath is dependent on ClsC. Full article

Nafion, while a benchmark proton exchange membrane (PEM) for fuel cells, suffers from significant performance degradation at elevated temperatures and low humidity due to dehydration and diminished mechanical stability. To address these limitations, this study investigated the development and characterization of Nafion nanocomposite membranes incorporating sulfonated silica layered materials (sSLMs). The inherent lamellar structure, high surface area, and abundant sulfonic acid functionalities of sSLMs were leveraged to synergistically enhance membrane properties. Our results demonstrate that sSLM incorporation significantly improved ion exchange capacity, water uptake, and dimensional stability, leading to superior water retention and self-diffusion at higher temperatures. Critically, the nanocomposite membranes exhibited remarkably enhanced proton conductivity, particularly under demanding conditions of 120 C and low relative humidity (i.e., 20% RH), where filler-free Nafion largely ceases to conduct. Single H₂/O₂ fuel cell tests confirmed these enhancements, with the optimal sSLM-Nafion nanocomposite membrane (N-sSLM₅) achieving a two-fold power density improvement over pristine Nafion at 120 C and 20% RH (340 mW cm⁻² vs. 117 mW cm⁻² for Nafion). These findings underscore the immense potential of sSLM as a functional filler for fabricating robust and high-performance PEMs, paving the way for the next generation of fuel cells capable of operating efficiently under more challenging environmental conditions. Full article

Excessive carbon dioxide (CO₂) emissions represent a critical challenge in mitigating global warming, necessitating advanced separation technologies for efficient carbon capture. Silica-based membranes have attracted significant attention due to their exceptional chemical, thermal, and mechanical stability under harsh operating conditions. In this study, we introduce a novel layered hybrid membrane designed based on amine-functionalized silica precursors, where a distinct affinity gradient is engineered by incorporating two types of amine-functionalized materials. The top layer was composed of high-affinity amine species to maximize CO₂ sorption, while a sublayer with milder affinity facilitated smooth CO₂ diffusion, thereby establishing a continuous solubility gradient across the membrane. A dual approach, combining comprehensive experimental testing and rigorous theoretical modeling, was employed to elucidate the underlying CO₂ transport mechanisms. Our results reveal that the hierarchical structure significantly enhances the intrinsic driving force for CO₂ permeation, leading to superior separation performance compared to conventional homogeneous facilitated transport membranes. This study not only provides critical insights into the design principles of affinity gradient membranes but also demonstrates their potential for scalable, high-performance CO₂ separation in industrial applications. Full article

The application of an ultrafiltration (UF) process with periodic membrane cleaning with the use of alkaline detergent solutions was proposed for the recovery of wash water from car wash effluent. In order to test the resistance of the membranes to the degradation caused by the cleaning solutions, a pilot plant study was carried out for almost two years. The installation included an industrial module with FP100 tubular membranes made of polyvinylidene fluoride (PVDF). The module was fed with synthetic effluent obtained by mixing foaming agents and hydrowax. To limit the fouling phenomenon, the membranes were cleaned cyclically with P3 Ultrasil 11 solution (pH = 11.7) or Insect solution (pH = 11.5). During plant shutdowns, the membrane module was maintained with a sodium metabisulphite solution. Changes in the permeate flux, turbidity, COD, and surfactant rejection were analysed during the study. Scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy (FTIR) analysis were used to determine the changes in the membrane structure. As a result of the repeated chemical cleaning, the pore size increased, resulting in a more than 50% increase in permeate flux. However, the quality of the recovered wash water did not deteriorate, as an additional separation layer was formed on the membrane surface due to the fouling phenomenon. Full article

This study investigates the pathophysiological process of healed perforated corneal ulcers (HPCUs) in humans. All subjects underwent keratoplasty due to opacities or leakage from HPCUs. Half of each specimen was fixed with 4% glutaraldehyde for transmission electron microscope (TEM) examination. The other half was fixed in 10% formaldehyde for immunofluorescence (IF) examination. TEM identified layered structures with two cell types (polygonal and elongated) connected by gap or adherent junctions during early stage of healing. Both apoptotic and mitotic changes were found in both types of cells. There were no endothelial cells or Descemet’s membrane (DM) present in early stage of healing. During the intermediate stage, the healed area comprised three layers: epithelium, Bowman’s layer, and stroma, with an increase in stromal collagen. Later, adjacent endothelial cells crept in, forming DM and completing the cornea’s 5-layer structure. IF examinations revealed that vimentin⁺ and α-smooth muscle actin (αSMA)⁺ myofibroblasts gathered around the damaged site. Proliferating cell nuclear antigen⁺ cells, which indicated cell proliferation, were found in both cells. Anti-phospho-histone H2AX antibodies were found in some epithelial cells. CK14-positive cells were only found in superficial polygonal cells. Corneal wound healing is a complex process that includes apoptosis, cell migration, mitosis, differentiation, and extracellular matrix remodeling. Full article

In the present study, we developed a moxifloxacin (MXF)-encapsulated liposome-enriched alginate nanocomposite hydrogel coating. MXF was encapsulated in soy lecithin (SL:MXF:2:1) via the probe sonication method with an average efficiency of 80%. Two different manufacturing methods, including a micropipetting and a T-shaped microfluidic junction (TMJ) device technique, were used to incorporate the MXF-encapsulated liposomes into hydrogel matrices and layered as a coating on polymeric substrate material. Drug encapsulation and its incorporation into the hydrogel matrix significantly enhanced its stability and facilitated a prolonged drug release profile. A relatively rapid drug release was observed in the MXF-encapsulated liposome-loaded polymeric particulate layer developed via the micropipetting than the TMJ device technique. The findings confirmed sustained drug release behavior due to a hydrogel particulate structural uniformity conferred by the micromachine device, TMJ. Thus, these nanocomposite hydrogel coatings achieved can serve as a promising candidate for the treatment of ophthalmic or mucosal membrane infections. Full article

The primary challenge associated with stainless steel in fuel cell operation is its susceptibility to corrosion, which leads to increased contact resistance and subsequent degradation of electrochemical performance. In general, the protective layers have been loaded onto the metal surface by widely used traditional techniques such as physical vapor deposition (PVD), or cathode arc ion plating. However, the above sputtering and evaporation ways require a high-vacuum condition, complicated experimental setups, higher costs, and an elevated temperature. Therefore, herein the achievement for uniform coatings over a large surface area has been realized by using a cost-effective strategy through a complete wet chemical process. The synergistic regulation of two conductive components and a plastic additive has been employed together with the entrapment of a surfactant to optimize the microstructure of the coating surface. The assembly of layered graphite and a polystyrene sphere could maintain both the high corrosion resistance feature and excellent electrical conductivity. In particular, the intrinsic vacant space in the above physical barriers has been filled with fine powders of indium tin oxide (ITO) due to its small size, and the interconnected conductive network with vertical/horizontal directions would be formed. All the key technical targets based on the U.S. Department of Energy (DOE) have been achieved under the simulated operating environments of a proton exchange membrane fuel cell. The corrosion current density has been measured as low as 0.52 μA/cm² (for the sample of graphite/mixed layer) over the applied potentials from −0.6 V to 1.2 V and its protective efficiency is evaluated to be 99.8%. The interfacial contact resistance between the sample and the carbon paper is much less than 10 mΩ·cm² (3.4 mΩ·cm²) under a contact pressure of 165 N/cm². The wettability has been investigated and its contact angle has been evolved from 48° (uncoated sample) to even 110°, providing superior hydrophobicity to prevent water penetration. Such an innovative approach opens up new possibilities for improving the durability and reducing the costs of carbon-based coatings. Full article

Background and Objective: In recent years, the success rate of treating refractory macular holes with internal limiting membrane (ILM) inversion has significantly increased. However, closure remains challenging for large macular holes even after ILM inversion. Here, we report the evaluation of amniotic membrane coverage for intractable large macular holes. Methods: We retrospectively analyzed five eyes of five patients (three males, two females; mean age 70.6 ± 13.3 years) with refractory macular holes that did not close after ILM inversion performed at our institution from June 2022 to May 2024 and were followed up for more than 6 months. Preoperative macular hole dimensions were assessed using optical coherence tomography (OCT). Surgery was performed using 27-gauge transconjunctival vitrectomy without ILM peeling. Two layers of amniotic membrane were placed in the macular center using a double-headed technique under air tamponade, followed by a complete vitreous fluid exchange with 10% sulfur hexafluoride gas. Postoperative outcomes were evaluated using OCT for macular hole closure and visual function assessment 6 months postoperatively. Results: The preoperative macular hole size was 1072.200 ± 189.043 μm, and the preoperative logMAR visual acuity was 1.222 ± 0.278. All macular holes closed postoperatively, with a postoperative logMAR visual acuity of 0.518 ± 0.165. Conclusions: The amniotic membrane coverage technique for intractable large macular holes was found to be an effective method contributing to macular hole closure and visual acuity improvement postoperatively. Full article

The flow rate strategies of deionized water have a significant impact on the mass transfer process of proton exchange membrane (PEM) electrolyzers, which are critical for the efficient and safe operation of hydrogen production systems. Electrochemical impedance spectroscopy is an effective tool for distinguishing different kinetic processes within the electrolyzer. In this study, three different Ti-felt porous transport layers (PTLs) are tested with two flow rate modes, constant flow (50 mL/min) and periodic cycling flow (10 mL/min–50 mL/min–10 mL/min), to investigate the influence of flow rate strategies on the mass transfer impedance of the electrolyzer. The following observations were made: (1) For PTL with better performance, the flow rate of the periodic cycling flow has little effect on its mass transfer impedance, and the mass transfer impedance of the periodic circulation flow mode is not much different from that of the constant flow. (2) For PTL with poorer performance, in the periodic cycling mode, the mass transfer impedance at 10 mL/min is smaller than that at 50 mL/min, but both are higher than the impedance under constant flow. The conclusions of this study provide a theoretical basis for the flow management of PEM electrolytic hydrogen production systems. Full article