Search Results (334)

Reverse osmosis (RO) is the most widely used technology in seawater desalination, accounting for around 70% of installations worldwide due to its efficiency and lower energy consumption compared to conventional thermal processes. However, a major challenge for RO is concentration polarization (CP), a phenomenon that reduces permeate flow, increases osmotic pressure, and compromises salt rejection, affecting the useful life of the membranes. In this work, an RO pilot plant was operated with synthetic solutions ranging from 4830 to 39,850 mgL⁻¹ at pressures between 0.69 and 5.79 MPa, to analyze and predict CP behavior. The results obtained showed salt rejection percentages ranging from 98.80% to 99.63%. The adjusted polynomial models presented correlation coefficients close to unity, which supports their high predictive capacity and statistical robustness for estimating the behavior of CP as a function of pressure. These models were implemented in Python software, allowing for the simulation of non-experimental scenarios and the anticipation of critical conditions that could compromise the RO process. Therefore, this work provides a robust predictive simulation tool to optimize RO processes and ensure the sustainable supply of drinking water in regions with water availability problems. Full article

This study employed tensile test, hydrogen permeation measurements, and potentiodynamic polarization testing to investigate the mechanical properties, hydrogen diffusion coefficients, and electrochemical behavior of X80 steel. A multifield coupled finite element (FE) model was developed that incorporated the mechano-electrochemical (M-E) effect to analyze the stress–strain distribution, anodic equilibrium potential, cathodic exchange current density, and hydrogen distribution characteristics at pipeline corrosion defects under varying tensile strains. The results indicated that tensile strain significantly modulated the anodic equilibrium potential and cathodic exchange current density, leading to localized hydrogen accumulation at corrosion defects. The stress concentration and plastic deformation at the defect site intensified as the tensile strain increased, further promoting hydrogen enrichment. The study concluded that the M-E effect exacerbated hydrogen enrichment at the defect sites, increasing the risk of hydrogen-induced cracking. The simulation results showed that the hydrogen distribution state aligned with the stress–hydrogen diffusion coupling model when considering the M-E effect. However, the M-E effect slightly increased the hydrogen concentration at the defect. These findings provide critical insights for enhancing the safety and durability of hydrogen transmission pipelines. Full article

Background/Objectives: This study aimed to enhance the vaginal permeation of buserelin acetate (BA), a synthetic gonadotropin-releasing hormone (GnRH) analogue, by evaluating various permeation enhancers (PEs) using a validated reversed-phase high-performance liquid chromatography (RP-HPLC) method and an ex vivo porcine vaginal model. Methods: A robust RP-HPLC method was developed and validated according to ICH Q2 (R2) guidelines to enable accurate quantification of BA in permeation samples. The analytical method demonstrated high specificity, linearity (R² = 0.9999), accuracy (98–102%), precision (%RSD < 2%), robustness, and stability. Using this method, ex vivo permeation studies were conducted with six different PEs: 2-hydroxypropyl-β-cyclodextrin, sodium dodecyl sulfate, poloxamer 188, Span 80, Tween 80, and chitosan. Results: Among all tested PEs, chitosan demonstrated the best enhancement of BA permeation. It achieved the highest flux (J) (0.64 ± 0.03 × 10⁻² µg/cm²·h) and apparent permeability coefficient (P_app) (16.20 ± 0.84 × 10⁻⁵ cm/h), both of which were statistically significantly higher (p < 0.05) than those of all other enhancer groups. Kinetic modelling indicated a non-Fickian, biphasic permeation mechanism best described by the Makoid–Banakar model. Conclusions: These findings highlight chitosan’s potential as an effective intravaginal delivery vehicle for peptide therapeutics and establish the validated HPLC method as a reliable platform for future formulation development and translational studies in mucosal drug delivery. Full article

Hydrogen-induced steel embrittlement imposes a technical difficulty in facilitating effective and safe hydrogen transportation via pipelines. This investigative study assesses the potency of polyvinylidene fluoride (PVDF)–graphene-based composite coatings in the inhibition of hydrogen permeation. Spin coating was the method selected for this study, and varying graphene concentrations ranging from 0.1 to 1wt% were selected and applied to 306 stainless steel substrates. A membrane permeation cell was used in the evaluation of hydrogen permeability, while the impact of graphene loading on coating performance was analyzed using the response surface methodology (RSM). The outcomes showed an inversely proportional relationship between the graphene concentration and hydrogen ingress. The permeation coefficient for pure PVDF was recorded as 16.74, which decreased to 14.23, 12.10, and 11.46 for 0.3, 0.5, and 1.0 wt% PVDF-G, respectively, with the maximum reduction of 31.6% observed at 1.0 wt%. ANOVA established statistical significance, along with indications of strong projection dependability. However, the inhibition reduction stabilized with increasing graphene concentrations, likely caused by nanoparticle agglomeration. The results support the notion of PVDF–graphene’s potential as a suitable coating for the transformation of pipelines for hydrogen transport infrastructure. This research will aid in the establishment of suitable contemporary barrier coating materials, which will enable the safe utilization of hydrogen energy in the current energy transportation grid. Full article

Some propylene glycol ethers (PGEs) have been associated with reproductive toxicity. Ethoxypropanol (PGEE) and propoxypropanol (PGPE) are two common PGEs found in many commercial products. Although skin exposure is frequent when handling such products, no studies have investigated their skin absorption. Neat or aqueous concentrations of PGEs were applied with different concentrations on previously frozen human skin according to OECD guidelines. We also explored the use of frozen skin for skin irritation screening. Our results show that both PGEs readily permeate human skin (permeation coefficients: Kp_PGEE = 0.0005–0.002 cm/h; Kp_PGPE = 0.0002–0.002 cm/h; rates: J_PGEE = 447.5–1075.2 µg/cm²/h; J_PGPE = 193.9–826.1 µg/cm²/h; and time lag: 2–5 h). The permeability rate was four times greater for PGPE diluted in water compared to neat, and double for PGEE. Increasing the water content increased PGEE skin permeation but had no effect on PGPE. Cleaning products contain 1–5% PGEs, and water-based paints 10–50%, thus increasing the potential for skin uptake in consumers. Our skin irritation results were inconsistent, so we conclude that skin irritation cannot be assessed with previously frozen human skin. Future studies should assess the irritation using fresh skin and investigate the risk of health effects from PGEs exposures. Full article

The hydrogen/deuterium permeation behavior of X52MS pipeline steel with three thicknesses was investigated using the gas/liquid phase permeation method by changing the current density and regulating the surface roughness. The permeation curves under different conditions were obtained, the hydrogen/deuterium diffusion coefficients and related important parameters were calculated, and the surface morphology of the hydrogen-filled side was observed using scanning electron microscopy. It is found that the hydrogen diffusion coefficient and diffusion flux increase gradually with an increase in the hydrogen charging current density, while the hydrogen infiltration lag time gradually decreases. With the increase in surface roughness of the specimen, the corrosion degree of the surface after hydrogen penetration decreases, the hydrogen diffusion coefficient gradually decreases, and the penetration time, lag time, and hydrogen concentration on the cathode side gradually increase. Full article

Chromium-molybdenum steels are extensively used in manufacturing large-volume seamless hydrogen storage vessels, but they still suffer from the hydrogen embrittlement problem. In this study, electrochemical cathodic hydrogen charging is utilized to investigate the hydrogen embrittlement of 4130X steels, with emphasis on the influence of charging current density and temperature on hydrogen permeation and hydrogen embrittlement susceptibility. The hydrogen penetration rate and hydrogen diffusion coefficient of 4130X steel both increase with an increase in hydrogen-charging current density and temperature. The results demonstrate that the degree of hydrogen-induced degradation in tensile ductility is more marked with increasing hydrogen-charging current density, while the hydrogen embrittlement index exhibits a peak at a temperature of 308 K, in which brittle patterns like quasi-cleavage surfaces and crack formations occur. These findings are crucial for understanding hydrogen-induced embrittlement and determining test temperatures of hydrogen-related engineering material applications. Full article

Background/Objectives: The oral cavity represents a convenient route of administration for drugs that exhibit significant hepatic first-pass extraction. In this study, the mucosal permeation properties of selected active pharmaceutical ingredients (APIs) incorporated into oral cavity drug products that are approved by the U.S. Food and Drug Administration were quantified using the human-derived sublingual HO-1-u-1 and buccal EpiOral™ in vitro tissue models. Methods: Epithelial barrier properties were monitored using propranolol and Lucifer Yellow as prototypic transcellular and paracellular markers. APIs were dissolved in artificial saliva, pH 6.7, and transepithelial flux from the apical to the basolateral compartment was quantified using HPLC. Results: Apparent permeability coefficients (Papp) calculated for these APIs in the sublingual HO-1-u-1 tissue model varied from Papp = 2.72 ± 0.06 × 10⁻⁵ cm/s for asenapine to Papp = 6.21 ± 2.60 × 10⁻⁵ cm/s for naloxone. In contrast, the buccal EpiOral™ tissue model demonstrated greater discrimination power in terms of permeation properties for the same APIs, with values ranging from Papp = 3.31 ± 0.83 × 10⁻⁷ cm/s for acyclovir to Papp = 2.56 ± 0.68 × 10⁻⁵ cm/s for sufentanil. The tissue-associated dose fraction recovered at the end of the transport experiment was significantly increased in the buccal EpiOral™ tissue model, reaching up to 8.5% for sufentanil. Conclusions: Experimental permeation data collected for selected APIs in FDA-approved oral cavity products will serve as a training set to aid the development of predictive computational models for improving algorithms that describe drug absorption from the oral cavity. Following a robust in vitro–in vivo correlation analysis, it is expected that such innovative in silico modeling strategies will the accelerate development of generic oral cavity products by facilitating the utility of model-integrated evidence to support decision making in generic drug development and regulatory approval. Full article

Bedaquiline is known to shorten the duration of therapy of tuberculosis but has limitations, e.g., poor solubility and adverse effects such as prolongation of the QT interval. In this study, bedaquiline was incorporated into an inherently targeted nanosystem for improved permeation of the drug, with ex vivo diffusion studies performed to investigate its penetration. The bedaquiline-loaded mannan–chitosan oligosaccharide lactate nanoparticles were prepared by a one-step ionic gelation probe sonication method. A PermeGear 7-in-line flow-through diffusion system was used for the ex vivo diffusion studies across porcine and human pericardia. Bedaquiline-loaded nanoparticles with a particle size and potential of 192.4 nm and 40.5 mV, respectively, were obtained. The drug-loaded mannan–chitosan nanoparticles had an encapsulation efficacy of 98.7% and drug loading of 0.6%. Diffusion data indicated a steady-state flux of 2.889 and 2.346 µg.cm⁻².min⁻¹ for porcine and human pericardia, respectively. The apparent permeability coefficients were calculated to be 2.66 × 10⁻⁴ cm.min⁻¹ and 2.16 × 10⁻⁴ cm.min⁻¹ for porcine and human pericardia, respectively. The lag phases were 52.72 min and 0 min for porcine and human pericardia, respectively. The drug permeation indicated a consistent and linear diffusion pattern across both porcine and human pericardia, additionally approving the porcine pericardium as a great comparable tissue to human tissue for pericardial studies. This study is the first to demonstrate ex vivo diffusion of bedaquiline-loaded, macrophage-targeted chitosan–mannan nanoparticles across both human and porcine pericardia, representing a novel platform for disease-targeted, localized treatment of TB pericarditis. Full article

The aim of this study was to develop double emulsions-filled chitosan hydrogel beads for topical application and to elucidate their skin penetration behavior. Double emulsions were prepared by a two-step emulsification method, and double emulsions-filled chitosan hydrogel beads were prepared by the extrusion method. The structure, stability, and skin penetration behavior were investigated. The results of yield efficiency (above 80%) and microstructure observation confirmed the feasibility of the preparation method. After loading the hydrophilic active ingredients (vitamin C) into this system, the retention ratio after storage for 6 weeks increased by 77.6%. Furthermore, hydrogel beads could promote the permeation of hydrophilic active ingredients loaded in double emulsions. When the concentration of chitosan was 3% (w/v), the permeation coefficient of vitamin C from hydrogel beads exhibited an increase (1.7-fold) compared with double emulsions. This system could affect the orderliness of lipid structures in the stratum corneum. In addition, the results indicated that this system could be used for the topical delivery of hydrophobic active ingredients (quercetin) as well. This is the first report of chitosan bead stabilization of W/O/W emulsions, yielding a 2.6-fold increase in skin uptake of hydrophilic actives. Full article

The focus of this work was to perform a preliminary study on the suitability of commercially available nanofiltration (NF) and reverse osmosis (RO) membranes for the separation of 1,3-propanediol (1,3-PD) post-fermentation solutions. The experiments were conducted with the use of AFC30 and AFC99 (PCI Membrane System Inc., Milford, OH, USA) as well as BW30 membranes (Dow FilmTec Co., Midland, MI, USA) and various feed solutions: selected compounds of fermentation broths, and synthetic and real fermentation broths. Firstly, it was found that for pure water, the AFC30 membrane was characterized by the highest performance. It clearly indicated that the membrane is the most open membrane and is characterized by a more porous structure. In turn, the lowest flux was noted for the AFC99 membrane. Studies performed with the use of synthetic broth found that for the BW30 membrane, the order in which the rejection coefficient (R) was obtained was glycerol~lactic acid > 1,3-propanediol > acetic acid. It clearly confirmed that the R increased with the molecular weight (MW) of the solution compounds. With regard to ions, it was found that SO₄²⁻ and PO₄³⁻ is characterized by higher R than Cl⁻ and NO₃⁻ ions. Multivalent ions are characterized by higher charge density, hydrated radius, hydration energy and MW. Finally, experiments performed with the use of the AFC30 membrane and real broths showed that the membrane ensured almost complete separation of 1,3-PD. With regard to organic acid, the separation performance was as follows: succinic acid > lactic acid > butyric acid > acetic acid > formic acid. It has been documented that the AFC30 membrane can be successfully used to concentrate the following ions: SO₄²⁻, PO₄³⁻, NO₃⁻ and Na⁺. Hence, most of the medium used for the fermentation process was retained by the membrane and may be reused, which is crucial for the scaling up of the process and reducing the total technology cost. With regard to the obtained permeate, it can be subsequently purified by other methods, such as distillation or ion exchange. For further development of the tested process, determining the retention degree for 1,3-PD and other solutes during long-term separation of real broth is necessary. Full article

Anion exchange membranes are utilised in cutting-edge energy technologies including electrolysers and fuel cells. Recently, these membranes have also emerged as a promising tool in CO₂ capture techniques, such as moisture-driven direct air capture and the separation of CO₂ from other gases, leveraging the moisture-induced sorption/desorption and diffusion of CO₂ in its ionic forms. In this study, we examine the absorption and permeation of CO₂ and CH₄ in two commercially available anion exchange membranes, Fumasep^® and Sustainion^®, under dry conditions. With the exception of CO₂ sorption in Fumasep^®, these measurements have not been previously reported. These new data points are crucial for evaluating the fundamental separation capabilities of these materials and for devising innovative CO₂ capture strategies, as well as for the simulation of novel combined processes. In a dry state, both materials demonstrate similar CO₂ absorption levels, with a higher value for Sustainion^®. The CO₂ solubility coefficient decreases with pressure, as is typical for glassy polymers. Fumasep^® exhibits higher CO₂/CH₄ ideal solubility selectivity, equal to ~10 at sub-ambient pressures, and higher diffusivity. The CO₂ diffusion coefficient increases with the CO₂ concentration in both membranes due to swelling of the matrix, varying between 0.7 and 2.2 × 10⁻⁸ cm²/s for Fumasep^® and between 1.6 and 9.0 × 10⁻⁹ cm²/s for Sustainion^®. CO₂ permeability exhibits a minimum at a pressure of approximately 2–3 bar. The CO₂ permeability in the dry state is higher in Fumasep^® than in Sustainion^®: 3.43 and 0.72 Barrer at a 2-bar transmembrane pressure, respectively. The estimated perm-selectivity was found to reach values of up to 40 at sub-ambient pressures. The CO₂ permeability and CO₂/CH₄ estimated perm-selectivity in both polymers are of a similar order of magnitude to those measured in fluorinated ion exchange membranes such as Nafion^®. Full article

This paper presents novel soluble (co)poly(hydroxyimide)s ((co)PIOH) based on 4,4′-oxydiphthalic anhydride (ODPA), 3,3′-dihydroxybenzidine (HAB), and 3,6-diaminodurene (D) with the 3/1, 1/1, and 1/3 HAB/D ratios. This chemical structure of the compounds provides the possibility of their future modification through the thermal rearrangement (polybenzoxazoles) or functionalization via Mitsunobu reaction (azo side-chain polyimides), i.e., obtaining new materials with interesting properties and therefore with expanded applications. Copolymers were characterized via FTIR, NMR, XRD, and GPC methods to confirm their structure, composition, and molar masses. The effect of copolymer composition on the thermal, mechanical, optical, and permeation properties studied for He, O₂, N₂, and CO₂, as well as hydrophobicity, was investigated. They exhibited a large interval between the glass transition temperature and the decomposition temperature, making them promising for the thermoforming technique. Transmittance above 90% was noted in the visible range for all (co)PIOH films deposited on a glass substrate. Young’s modulus of fabricated membranes was in the range of 2.37 to 3.38 GPa. The highest permeability coefficients were recorded for (co)PIOH with a 1:3 HAB-to D-ratio. Full article

UV radiation can change the internal molecular composition, macroscopic rheological properties, and microscopic chemical composition of asphalt. To study the effect of ultraviolet aging on asphalt and its structure–activity relationship, its rheological properties were measured by dynamic shear rheology and multiple stress recovery creep tests, its chemical compositions were measured by component composition, elemental composition, and infrared spectrum tests, and its molecular weight, distribution, and molecular structure were determined by gel permeation chromatography and nuclear magnetic resonance tests. Then, the molecular weight and molecular structure, rheological properties, and microchemical aging behavior of asphalt after UV aging were characterized by correlation analysis, and the structure–activity relationship was analyzed. The results show that the deformation resistance and elastic recovery ability of asphalt after UV aging are enhanced, and the flow performance is decreased. The ultraviolet radiation caused the aromatic hydrocarbons containing naphthenes and long alkyl chains in the asphalt to break and connect with asphaltenes with a ring structure. The asphaltene content in each bitumen sample exceeded 46%, and that in KL reached 55%, indicating that the bitumen changed into a gel structure. UV aging causes the aggregation of asphalt molecules, and the aggregation of molecules narrows the molecular distribution boundary and moves in the direction of macromolecules, resulting in the reduction of the dispersion coefficient by 2–10%. Hydrogen atoms will undergo condensation and substitution reactions due to long-chain breaking, cyclization, or aromatization under UV action, and the breaking of C=C bonds in carbon atoms will increase the stable aromatic ring, strengthen the stiffness of the molecular backbone, and make it difficult for the backbone to spin. Through correlation analysis, it was found that the molecular composition index could characterize the aging behavior index of asphalt, and that the aromatic structure was the most critical molecular change. Further, it was found that the sulfoxide group and carbonyl group could be used as evaluation criteria for the UV aging of asphalt because the correlation between them was above 0.7. This study provides an essential index reference for evaluating the performance change of asphalt under ultraviolet aging to save testing time. Moreover, the molecular structure characterization revealed the changes in internal molecular composition that were behind the observed aging properties, providing a theoretical basis for research on asphalt anti-aging technology. Full article

Poly(lactic acid) (PLA) is one of the most important bio-based and industrial compostable materials in food packaging. Its barrier properties towards oxygen and moisture are well documented. However, data on barrier properties of PLA towards organic molecules are scarce in the literature. This study investigated the diffusion of various organic molecules, including n-alkanes, 1-alcohols, 2-ketones, ethers, esters, amines, and aromatics, in two commercial PLA films with thicknesses of 20 µm and 30 µm. The diffusion coefficient (D_P) values were determined from lag time in permeation tests conducted at temperatures ranging from 20 °C to 90 °C. The films were also characterized in terms of crystallinity, rigid and mobile amorphous fractions, and molecular weight. Activation energies (E_A) were calculated based on the temperature dependence of the D_P using the Arrhenius approach. In total, 290 D_P values for 55 individual substances were determined, and 38 E_A values were derived from these data. The E_A correlated well with the molecular volume of the investigated substances. Moreover, the pre-exponential factor D₀ showed a correlation with E_A. These correlations enabled the establishment of diffusion modeling parameters for PLA, allowing the prediction of D_P for untested substances. The diffusion behavior of PLA was further compared with the literature data for polyethylene terephthalate and polyethylene naphthalate, providing insights into the relative performance of these materials. Full article