Search Results (3,262)

Polymeric membrane systems have emerged as an effective approach for water separations due to their high separation efficiency, simplicity, and adaptability to a wide range of water treatment applications. However, traditional membrane fabrication processes often rely on toxic organic solvents, such as N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc), which pose environmental and health risks. Eco-friendly solvents have been investigated as an alternative to traditional toxic solvents. This study investigates the fabrication and performance of polymeric membranes using eco-friendly solvent systems, with a focus on bilayer membranes designed to improve separation performance over traditional single-layer membranes. Membranes were fabricated using eco-friendly solvents, Rhodiasolv© PolarClean and gamma-valerolactone in combination with polymers polysulfone (PSf) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Membranes were fabricated using nonsolvent-induced phase separation (NIPS) through doctor blade extrusion (DBE) and slot-die coating (SDC) methods in order to compare traditional laboratory-scale casting methods (DBE) with scalable fabrication techniques (SDC). Bilayer membranes were investigated to address limitations presented by single-layer membranes, with polydopamine (PDA) incorporated as an adhesion-promoting additive. Membrane characterization included scanning electron microscopy (SEM), contact angle measurements, and tensile testing, along with water permeability and solute rejection tests. Results showed that polymer concentration and casting method influenced permeability and solute rejection, with the SDC bilayers reaching the highest initial BSA rejection. Filtration used deionized water and model aqueous feeds containing 100 ppm NaCl, 100 ppm CaCl₂, and 100 ppm bovine serum albumin (BSA). Full article

Background: Nickel–titanium (Ni-Ti) instruments are continuously exposed to irrigating solutions during root canal preparation, which may affect their surface integrity. Evidence regarding the combined morphological and elemental effects of contemporary irrigation protocols on heat-treated single-file systems remains limited. This study evaluated the effects of different irrigation protocols on the surface morphology and elemental composition of Super One File Ni-Ti instruments using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Methods: Thirty Super One File instruments (size 25/.04) were randomly allocated to three groups: distilled water (DW), a sequential NaOCl–EDTA–NaOCl irrigation protocol (NEN), and a NaOCl/HEDP continuous chelation protocol. Instruments were continuously rotated in the assigned solution for 20 min. Surface morphology was assessed by SEM and elemental composition by EDS. SEM data were analysed using the Fisher–Freeman–Halton exact test, whereas EDS data were analysed using linear mixed-effects models with post hoc pairwise comparisons (α = 0.05). Results: SEM analysis revealed protocol- and region-dependent differences in surface alterations. The NEN group showed significantly higher corrosion and pitting frequencies than the DW group in selected regions, whereas no significant differences in these outcomes were detected between the NEN and HEDP groups. EDS analysis showed significant protocol × region interactions for all elements except Cl. These differences were most pronounced in the coronal region, where the HEDP group exhibited lower Ni and Ti and higher O, P, Na, and Ca levels than the DW and NEN groups. Conclusions: The tested irrigation protocols produced distinct, region-dependent surface responses in Super One File instruments, highlighting the potential influence of irrigation chemistry on Ni-Ti instrument surfaces under controlled experimental conditions. The clinical and mechanical implications of these alterations remain to be established. Full article

This study investigated the corrosion resistance of laser-cladded AlCoCrFeNi high-entropy alloy coatings with varying TiO₂ content (0 wt.%, 0.5 wt.%, 1.0 wt.%, and 1.5 wt.%) in 3.5 wt.% NaCl solution. Optimal cladding parameters (1500 W, 40 mm/s, 11.9 g/min) were determined via orthogonal experiments. TiO₂ promoted Ti-rich BCC2-phase precipitation, increased corrosion potential (from −1.4185 V to −0.6841 V), decreased corrosion current density (from 2.33 × 10⁻⁴ to 2.28 × 10⁻⁶ A/cm²), and enhanced charge-transfer resistance. XPS analysis demonstrated that TiO₂ promoted the enrichment of FeO, Cr₂O₃, and TiO₂ components in the passive film while reducing the Al₂O₃ fraction, leading to the formation of a dense and stable composite passive film that effectively inhibited chloride ion attack. In summary, an appropriate amount of TiO₂ doping significantly enhances the corrosion resistance of laser-cladded AlCoCrFeNi HEA coatings, with the 1.5 wt.% addition being the best-performing among the investigated compositions. Full article

Sweat testing is central to cystic fibrosis diagnosis, but conventional analysis depends on clinical instrumentation, creating a need for portable point-of-care alternatives. As Part 1 of this two-part study, we systematically optimized Na⁺- and Cl⁻-selective colorimetric optodes and their measurement protocols for potential integration into a wearable device for in situ sweat analysis. Fifteen chromoionophore-based sensor compositions were screened over the physiologically relevant range of 5–100 mmol/L. Candidate optodes were selected based on stability in NaCl solutions and artificial sweat, hysteresis below 0.1 log units, and equilibration times under 15 min. Their analytical performance was evaluated by spectrophotometry and digital color analysis using smartphones and research-grade cameras, with a robustness parameter used to quantify signal reliability under different imaging conditions. A simple smartphone setup provided more robust performance than the tested laboratory imaging configurations. Incorporating light-scattering TiO₂ particles into the PVC matrix produced opaque films that significantly reduced interference from colored samples without compromising sensitivity or response kinetics. Validation in artificial sweat yielded recoveries above 93% across pH 5.5–8.0. These results establish optimized sensor compositions and measurement conditions for colorimetric Na⁺ and Cl⁻ determination in sweat and provide the analytical basis for wearable-device development in Part 2. Full article

Saline–alkali stress is a major abiotic constraint limiting crop production worldwide. To address the lack of a systematic evaluation system for oat seedling saline–alkali tolerance adapted to soda saline–alkali soil in the Hetao Plain, 80 oat accessions with diverse genetic backgrounds were used as materials in this study. Seedlings were subjected to stress induced by a 75 mM composite saline–alkali solution (NaCl:Na₂SO₄:NaHCO₃:Na₂CO₃ = 1:9:9:1), which simulates the typical salt composition of local soda saline–alkali soils. Six seedling-stage traits, including seedling emergence rate, chlorophyll content, relative electrolyte leakage, malondialdehyde content, free proline content, and soluble sugar content, were determined, and the saline–alkali tolerance coefficient of each trait was calculated. Principal component analysis, the subordinate function method, and hierarchical cluster analysis were integrated to construct a comprehensive evaluation system for saline–alkali tolerance. The results showed that the coefficients of variation of all tested traits ranged from 21.15% to 113.66%, indicating abundant genotypic variation among different germplasms. Three principal components with eigenvalues greater than 1 were extracted, with a cumulative contribution rate of 65.79%; these components mainly reflected cell membrane status, osmotic substance accumulation, and growth performance, respectively. The comprehensive evaluation value (D-value) ranged from 0.290 to 0.884, and stepwise regression analysis identified soluble sugar, relative electrolyte leakage, and proline as core screening indicators. Combined with hierarchical cluster analysis, the 80 oat germplasms were classified into five saline–alkali tolerance grades, and significant differences in key traits were observed among grades. Germplasms with high saline–alkali tolerance performed outstandingly in maintaining membrane integrity and accumulating osmotic substances. This study established a practical multi-index comprehensive evaluation system for seedling-stage saline–alkali tolerance in oats adapted to soda saline–alkali environments and identified three candidate tolerant germplasm resources. These results provide technical methods and preliminary candidate materials for oat saline–alkali tolerance breeding and saline–alkali land utilization in the Hetao Plain, while the tolerance performance of the selected germplasms still needs to be verified under multi-concentration stress and field conditions. Full article

Enterococcus lactis KUST2812 is a halotolerant strain isolated from broad bean paste (BBP). It shows strong potential as a safe fermentation starter due to its high survival rate (98.32% in 18% NaCl), absence of hemolytic activity, and susceptibility to clinically relevant antibiotics, with resistance limited to intrinsic traits. Growth and metabolic dynamics suggest that salt stress decouples growth from tyrosine catabolism: while 6% NaCl significantly inhibited bacterial cell growth, tyrosine depletion occurred within 12 h under 6% NaCl, compared with the 96 h required under non-saline conditions. Multi-omics analyses suggest a molecular network associated with this tyrosine conversion under salt stress. Two tyrosine decarboxylase genes (tdc) were upregulated by 1.85- and 6.50-fold, respectively. The tyrosine-specific transporter gene tyrP was upregulated 4.99-fold, and the protein synthesis-associated gene tyrS was upregulated 4.93-fold. These changes collectively support a diversified tyrosine utilization strategy of E. lactis KUST2812. Moreover, coordinated responses involving the Na⁺/H⁺ antiporter system, compatible solute transporters, and oxidative stress markers contributed to the metabolic basis for salt adaptation of this strain. Evaluation in BBP fermentation suggested that E. lactis KUST2812 may reduce tyrosine accumulation without causing a significant increase in tyramine. These findings offer a potential microbial resource and a theoretical basis for managing tyrosine-related quality issues in fermented foods. Full article

Salt stress restricts cucumber seedling establishment by impairing root development, photosynthesis, ion homeostasis, and redox balance. This study examined whether potassium silicate (K₂SiO₃) could partially alleviate these responses under hydroponic sodium chloride (NaCl) stress. Cucumber seedlings were exposed to six treatments: a nutrient-solution control, K₂SiO₃ alone supplying 1.0 mmol L⁻¹ silicon (Si), 75 mmol L⁻¹ NaCl, and NaCl combined with K₂SiO₃ supplying 0.5, 1.0, or 2.0 mmol L⁻¹ Si. Growth, root morphology, photosynthetic pigments, gas exchange, chlorophyll fluorescence, photosystem II (PSII) energy partitioning, oxidative injury, antioxidant enzyme activities, osmotic adjustment, and ion status were evaluated at 7 and 14 d. NaCl markedly reduced seedling growth, root development, net photosynthetic rate, PSII photochemical performance, and electron transport, while increasing leaf sodium (Na⁺), malondialdehyde accumulation, non-photochemical quenching, non-regulated energy loss, proline, and soluble sugar. K₂SiO₃ partially alleviated these changes. The treatment supplying 1.0 mmol L⁻¹ Si produced the strongest integrated recovery of growth, root activity, photosynthetic performance, PSII function, and oxidative status. The treatment supplying 2.0 mmol L⁻¹ Si resulted in the lowest leaf Na⁺ concentration and the highest leaf potassium (K⁺)/Na⁺ ratio among salt-stressed seedlings but did not produce the greatest growth recovery. These findings suggest coordinated changes in photosynthesis, photochemical energy use, redox status, and ion balance. Because K₂SiO₃ supplied both Si and K⁺, the results represent responses to K₂SiO₃ supplementation rather than Si-specific effects. Full article

Polytetrafluoroethylene/Polyetheretherketone (PTFE/PEEK) corrosion-resistant coatings were prepared on the surface of 7075 aluminum alloy by the electrostatic powder spraying technique (EPST). To achieve a denser microstructure and improved hydrophobic properties, we introduced nano-CeO₂ to fill the coatings and analyzed the mechanism of its effect on the different coating structures. The corrosion resistance of the coatings was evaluated using NaCl immersion. The results indicate that nano-CeO₂ enhances the coatings by filling local defects and forming a denser microstructural barrier, thereby improving the hydrophobicity and corrosion resistance of the composite coatings. Additionally, the addition of nano-CeO₂ to the 20 µm PTFE/PEEK composite coating increases structural heterogeneity and pore defects, reduces coating densification, and facilitates the penetration of corrosive media, thereby weakening the barrier capability of the coating. However, in the 50 µm PTFE/PEEK/CeO₂ composite coating, nano-CeO₂ particles fill part of the pre-existing defects and improve coating densification, thereby increasing the resistance to the penetration of corrosive media through the coating. This enhanced barrier effect delays the contact of corrosive media with the substrate and improves the corrosion resistance of the coating. In this study, the 50 μm PTFE/PEEK/CeO₂ composite coating with a nano-CeO₂ content of 0.5 wt.% exhibited the best corrosion resistance, with a corrosion current density of 8.02 × 10⁻⁴ μA·cm⁻², while |Z|_0.01Hz remained above 10⁶ Ω·cm² after 720 h of immersion in NaCl solution. Full article

Millions of End-of-Life (EoL) reverse osmosis (RO) membranes are discarded each year by desalination facilities worldwide. This poses a significant environmental challenge, as large amounts of solid waste are often managed through landfilling or incineration. Recycling EoL RO membranes for reuse as nanofiltration (NF) or ultrafiltration (UF) membranes is an attractive pathway for the effective management of solid waste. However, the commonly adopted route to degrade the polyamide active layer of the EoL membranes for recycling and reuse requires high-intensity exposure of the membranes to the NaOCl solution. There is a need to develop a route to make membranes more responsive to the low dosage of NaOCl for recycling and reuse of the membranes. The current study explored that tailoring of the membrane active layer could generate a more responsive polyamide membrane to a mild concentration of NaOCl. This was achieved by incorporating monobenzoyl chlorinated aromatic reactants 4-nitrobenzoyl chloride (4-NC) and 3,5-dinitrobenzoyl chloride (3,5-DNC) into the active layer of the membranes. A minor concentration of the 4-NC and 3,5-DNC was added to the trimesoyl chloride-containing organic phase during interfacial polymerization with m-phenylenediamine. Owing to the presence of only one reactive site in 4-NC and 3,5-DNC, the reaction with m-phenylenediamine can hinder crosslinking in certain regions of the m-phenylenediamine and trimesoyl chloride polyamide active layer. This limited number of uncross-linked regions not only increases the membrane permeability with reasonable salt rejection but also makes the membranes more responsive to chlorine. This was realized when the permeate flux was found to be 108, 114, and 200 L m⁻² h⁻¹ for the M1 (control), M2 (4-NC), and M3 (3,5-DNC) membranes, respectively, at a feed pressure of 30 bar using 100 ppm of NaOCl for 24 h. On the other hand, the rejection of NaCl was decreased from 97 to 9.6, 93 to 7.1, and 91 to 3.6% with an increase in contact time from 2 h to 24 h for M1, M2, and M3 membranes, respectively. This exposure intensity was significantly less than that commonly used in the literature. Furthermore, the recycled modified membrane, especially M3, showed reversible fouling when the membranes were tested using bovine serum albumin as a model foulant in seawater scenarios. Full article

Saline–alkali stress severely restricts leafy vegetable growth by impairing photosynthesis, ion homeostasis, and oxidative balance. This study investigated whether exogenous melatonin could alleviate saline–alkali stress in pakchoi (Brassica rapa subsp. chinensis) through coordinated protection of photosynthetic electron transport, ionic balance, and antioxidant defense. Pakchoi plants were subjected to four treatments: normal nutrient solution (CK), 100 μM melatonin (MT), 100 mM mixed saline–alkali stress with NaCl:NaHCO₃ at 2:1 (SAS), and saline–alkali stress plus melatonin (SAS+MT). After 7 d, growth traits, gas exchange, chlorophyll fluorescence, OJIP transients, ion contents, osmotic adjustment, oxidative damage, and antioxidant enzyme activities were analyzed. Saline–alkali stress markedly inhibited growth, reduced photosynthetic pigment contents and gas exchange, impaired PSII photochemical performance, disrupted ion balance, and increased ROS accumulation and membrane damage. Compared with SAS, SAS+MT increased net photosynthetic rate (Pn) by 66.2%, effective quantum yield of PSII [Y_(II)] by 56.0%, electron transport rate (ETR) by 57.9%, and the performance index on absorption basis (PI_ABS) from 0.80 to 1.80. Melatonin also reduced Na⁺ content by 38.7%, increased the K⁺/Na⁺ ratio from 1.0 to 2.2, and enhanced superoxide dismutase (SOD),peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) activities by 20.5%, 24.4%, 29.2%, and 33.3%, respectively. These results indicate that melatonin alleviates saline–alkali injury in pakchoi by maintaining PSII electron transport, improving ion homeostasis, and strengthening antioxidant defense. Full article

Nitrogen (N) and phosphorus (P) influx into receiving water bodies leads to cultural eutrophication and, therefore, poses a major environmental challenge. Consequently, increasingly stringent discharge limits have been established, necessitating advanced wastewater treatment methods. In addition, phosphorus is a finite resource, with current reserves projected to last less than a century. The principles of the circular economy therefore emphasize not only the removal of N and P from wastewater, but also their recovery and reuse as fertilizers. This article presents two strong-base anion-exchangers impregnated with zirconium oxide (ZrO₂) nanoparticles to create the following: (1) a phosphorus-selective resin (Hybrid Anion Exchanger with ZrO₂ (HAIX-Zr)), with a Zr loading of 2.5–3% (m/m) and an ion-exchange capacity (IEC) of ≈35 mg PO₄³⁻ − P/g resin, and (2) a resin selective for both phosphorus and nitrate (Nitrate-Selective Resin with ZrO₂ (NSR-Zr)), with a Zr loading of 1.5–2% (m/m), a simultaneous phosphate IEC of ≈41.3 mg PO₄³⁻ − P/g resin, and a nitrate IEC of ≈41.3 mg NO₃⁻ − N/g resin. When loaded in a fixed-bed column, HAIX-Zr can treat > 300 Bed Volumes (BV) of wastewater to below the phosphate detection limit of 0.02 mg/L when the initial phosphate–phosphorus concentration is ≈11.0 mg/L and the two most common competing anions, Cl⁻ and SO₄²⁻, are present at ≈225 mg/L and ≈160 mg/L, respectively. Regeneration of the exhausted HAIX-Zr column with a 2% NaCl + 2% NaOH solution resulted in >95% P recovery, which can be processed to generate MgNH₄PO₄ (struvite), a slow-release fertilizer. A fixed-bed NSR-Zr column can treat ≈150 BV of wastewater to below the phosphate detection limit of 0.02 mg/L and nitrate detection limit of 0.05 mg/L when the initial phosphate–phosphorus concentration is 31 mg/L, the nitrate–nitrogen concentration is 12 mg/L, and the competing anions Cl⁻ and SO₄²⁻ are present at ≈175 mg/L and ≈155 mg/L, respectively. Regeneration of the exhausted NSR-Zr column with 2% KOH solution resulted in >92% recovery of nitrogen and phosphorus in a solution rich in nitrogen, phosphorus, and potassium, the essential ingredients of a fertilizer. Full article

Three kinds of surface treatments, including permanganate, molybdate, and phytic acid conversion films, were fabricated on La-Ce mischmetal containing AM60B magnesium alloy. Their effects on the corrosion and tribological behaviors of the alloy in 3.5 wt% NaCl solution were systematically investigated via Mott–Schottky analysis, electrochemical measurements, and friction–wear tests. The results show three surface treatments shift the flat band potential in the negative direction, reduce the corrosion current density, enlarge the electrochemical impedance arc radius, and decrease the friction coefficient, conferring remarkably enhanced corrosion and wear resistance to the alloy substrate. The performance enhancement is ascribed to the formation of uniform, dense conversion films that act as effective physical barriers, which impede the penetration of corrosive species, isolate the substrate from the aggressive aqueous environment, and improve the chemical and electrochemical stability of the alloy–solution interface. The comprehensive performance ranking of the three surface treatments in terms of corrosion and wear resistance is as follows: permanganate conversion film > molybdate conversion film > phytic acid conversion film. Full article

Density measurement with vibrating tube density meters is a fundamental technique in biotechnology, for example, as the metrological base for spectroscopy calibrations. However, conventional multi-point adjustments frequently rely on hazardous halogenated solvents. In this work, green alternatives for density calibration are evaluated with a focus on replacing hazardous substances while maintaining analytical performance. Propylene carbonate is identified as an intrinsic candidate standard for densities up to 1.20 g/mL, eliminating reliance on conventional halogenated liquids. For routine verification and system suitability testing, binary aqueous solutions of sodium chloride and guanidine hydrochloride are proposed as secondary standards. Guanidine hydrochloride solutions provide particular advantages due to their moderate viscosity and high refractometric sensitivity, allowing independent verification of composition and extended usability. In addition, historical density data for NaCl and CsCl solutions were re-evaluated to showcase that in silico modeling can derive density–temperature–composition relations with reasonable overall accuracy. Overall, the proposed approach demonstrates that accurate density calibration in bioanalytical laboratories can be achieved using low-toxicity, non-halogenated substances thereby reducing environmental impact while supporting fit-for-purpose analytical performance. Full article

To address the prevalent defects in industrially cast 8021 aluminum alloy for battery foil, including coarse iron-rich phases that sever the matrix and hard-to-remove micrometer-scale inclusions, alloys with different chemical compositions were manufactured on a 100-ton integrated industrial melting and holding production line. The regulatory principles and underlying mechanisms of Fe–Ce composite microalloying on solidification thermal behavior, melt purification efficiency, as-cast microstructure, mechanical properties, and corrosion resistance of the alloy were systematically investigated. The results show that when the mass fractions of Fe and Ce are 1.7% and 0.3%, respectively, the mean intercept length of the α-Al grains of the alloy is reduced by 29% compared with the reference alloy. The acicular iron-rich phases are modified into dispersively distributed short rod-like and granular particles, and the filtration removal efficiency of micro-inclusions in the melt is significantly improved. The ultimate tensile strength of the alloy reaches 94.0 MPa, and the elongation is increased to 44.2%. The corrosion current density in 3.5 wt.% NaCl solution is only 20% of that of the Ce-free reference alloy. Through multi-stage effects including melt purification, grain refinement and second-phase modification induced by joint Fe and Ce additions, the combined addition of Fe and Ce simultaneously improves the metallurgical quality and service performance of the alloy. This work provides theoretical support and engineering references for the stable industrial production of high-performance aluminum foil for lithium-ion battery packaging. Full article

Water–rock interaction (WRI) due to fluid invasion into formation fractures causes potential formation damage during drilling in hot dry rock (HDR) reservoirs. Due to the developed artificial fractures, drilling fluids will contact and interact with HDR reservoir fractures, leading to alterations in fracture characteristics. With the increasing popularity of brine-based drilling and completion fluids, these alterations induced by WRI could be further enhanced, which requires investigations. In this study, short-term WRI experiments between the HDR and three reactive solutions, including pure water and alkaline (pH = 10) 6 wt% NaCl/KCl solutions, under temperatures of 25 °C and 180 °C, were carried out. Rock-surface topography alterations were identified using laser scanning. Morphological alteration mechanisms were revealed through microscopic and mineralogical alteration determination using a field emission scanning electronic microscope. Hydrogeochemical simulations, including reaction kinetics and equilibrium, were conducted to support the mineralogical alterations. Implications of morphological alterations on fracture permeability were demonstrated based on a roughness–permeability model. The results show that interactions with the alkaline NaCl solution cause the smoothening of the rock surface due to a coating effect of secondary silicate precipitations, while interactions with pure water and the alkaline KCl solution result in rock-surface roughening because of feldspar dissolution, differential mineral dissolution and biotite hydrolysis dispersion. The secondary precipitations either cover or fill the pores and cracks, the dissolved feldspar enlarges the pores and cracks, the differential mineral dissolution coarsens the rock surfaces, and the biotite hydrolysis dispersion generates pores and cracks on its surfaces. An increase or a decrease in surface roughness induces a corresponding increase or decrease in fracture permeability, because the roughness augmentation (roughening) enlarges seepage channel spaces while roughness reduction (smoothening) narrows them. This work reveals potential formation damage induced by drilling fluid invasion into fractures within HDR geothermal reservoirs, and provides theoretical insights for mitigating such damage. Full article