Search Results (430)

Per- and polyfluoroalkyl substances (PFASs) are persistent environmental contaminants whose mobility in soil and groundwater is strongly controlled by adsorption and desorption processes. In saturated clay-rich soils, these processes are complex because PFASs interact with hydrated mineral surfaces, organic matter, metal oxides, exchangeable cations, and pore-water constituents. This review synthesizes the current literature on PFAS adsorption and desorption in saturated soils, with an emphasis on clay mineralogy, mineral–water interfaces, pore-water chemistry, and electrochemical double layer (EDL) effects. PFAS retention is influenced by molecular properties such as chain length, functional head group, and charge state, as well as soil properties such as organic carbon content, clay mineral type, surface charge, cation exchange capacity, and Fe/Al oxide content. Longer-chain PFASs and sulfonate-based compounds generally show stronger retention, while shorter-chain PFASs tend to remain more mobile. This review focuses particularly on how an EDL affects PFAS behavior in saturated clay systems. Unlike dry clay surfaces, saturated clay surfaces are covered by structured water, exchangeable ions, and diffuse counterion layers. These hydrated interfacial conditions influence how closely anionic PFASs can approach negatively charged clay surfaces, how dissolved cations reduce electrostatic repulsion or promote cation-mediated binding, and how effectively short-range interactions such as hydrophobic association, van der Waals forces, hydrogen bonding, and surface association contribute to adsorption. Desorption is also emphasized because adsorption does not necessarily represent permanent immobilization. Changes in pH, ionic strength, cation composition, dissolved organic matter, or competing solutes can weaken retention and promote PFAS release. Overall, PFAS mobility in saturated clay-rich soils should be interpreted as a coupled interfacial process rather than simple partitioning to soil solids. Future work should better connect molecular-scale mechanisms, EDL behavior, adsorption–desorption experiments, and saturated transport studies to improve predictions of PFAS retention and long-term groundwater release. Full article

Two bio-based insulating oils (BHOs) with average carbon chain lengths of approximately 18 and 22 were investigated as short- and long-chain BHOs. By constructing an oil-paper composite insulation system, the generation law of characteristic gases in the two systems was studied by partial discharge experiments. Based on the ReaxFF reaction molecular dynamics simulation under electrothermal coupling stress, the cracking path, cracking rate, evolution of oxygen-containing small molecules, and generation path of characteristic gases of cellulose polymer were revealed. Both systems produced H₂, CH₄, C₂H₂, C₂H₄, C₂H₆, CO, and CO₂, with CO₂ dominant and C₂H₆ least abundant. The short-chain BHO generated markedly higher amounts of H₂, CO, C₂H₂, and C₂H₄ than the long-chain BHO; after 15 min, its H₂ and CO concentrations were about 3.4- and 2.1-times those in the long-chain system, respectively. ReaxFF simulations showed that cellulose degradation in the short-chain BHO followed stepwise chain scission and continuous decarbonylation, favoring CO and unsaturated gas precursors. In contrast, cellulose chains disappeared faster in the long-chain BHO, producing more oxygen-containing organic fragments and C₁-C₅ oxygenated molecules and a higher small-molecule conversion ratio. Characteristic gas pathway analysis revealed that all seven gases could be generated from cellulose pyrolysis intermediates, and different oil environments primarily influenced gas generation behavior by altering the evolution pathways of these intermediates. These findings, at the molecular scale, elucidate the impact of BHO environments on the degradation mechanism of cellulose polymers, providing a theoretical basis for the condition assessment and design of environmentally friendly oil-paper insulation systems. Full article

Efficient recovery of long-chain dicarboxylic acids (LCDAs) from aqueous fermentation broths is a key challenge for the industrial development of bio-based LCDA production. This study evaluates liquid–liquid extraction (LLE) as a downstream recovery strategy, comparing physical extraction (PE) and reactive extraction (RE) for DCA 12, DCA 16, and DCA 18. The novelty of this work lies in demonstrating that LCDA extraction is governed by mechanisms fundamentally different from those of short- and medium-chain dicarboxylic acids. Whereas shorter chain dicarboxylic acids are mainly controlled by dissociation degree, LCDA recovery is strongly influenced by carbon-chain apolarity, low aqueous solubility, and compound losses through agglomeration, precipitation, and/or micellization. PEs enabled the selective recovery of the more hydrophobic DCA 16 and DCA 18 over DCA 12, confirming the dominant role of chain length in LCDA separation. In contrast, RE with Aliquat^®336 maximized total LCDA recovery, achieving extraction efficiencies above 85%, but with reduced selectivity. Validation in autoclaved fermentation broth from UCO feedstock confirmed the potential of Aliquat^®336 in octanol for high LCDA recovery, while revealing lower extraction efficiencies than in model mixtures due to broth matrix complexity. Overall, this study establishes LLE as a promising platform for LCDA recovery and highlights that future downstream process design must balance total recovery, chain-length selectivity, and broth-specific matrix effects. Full article

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants associated with cardiovascular diseases; however, the mechanisms underlying PFAS-induced vascular endothelial injury remain incompletely understood. In this study, we systematically evaluated the effects of 15 PFAS on endothelial morphology and cell viability with different carbon-chain lengths and functional groups in cultured bovine aortic endothelial cells. Morphological observations and MTT assays revealed that perfluorononanoic acid, perfluorodecanoic acid (PFDA), and perfluorooctane sulfonate (PFOS) markedly reduced cell viability, with estimated concentrations producing a 50% reduction in viability of 60.9, 34.7, and 87.3 µM, respectively, whereas the other tested PFAS did not reduce viability by 50% at concentrations up to 100 µM in bovine aortic endothelial cells. Among the perfluoroalkyl carboxylic acids, the reduction in cell viability increased with increasing carbon-chain length. Among perfluoroalkyl sulfonates, PFOS caused the greatest reduction in cell viability, whereas perfluorodecanesulfonate did not induce clear endothelial damage. Comparative analyses across multiple cell types showed that PFDA reduced cell viability broadly across all cell types examined, whereas PFOS caused a greater reduction in cell viability in bovine-derived cell types examined than in human- or porcine-derived cell types examined. Since PFDA and PFOS were the most cytotoxic compounds among perfluoroalkyl carboxylic acids and perfluoroalkyl sulfonates, respectively, in bovine aortic endothelial cells, they were selected to compare cell death signaling. In both PFOS- and PFDA-treated cells, the selected apoptosis- and pyroptosis-related markers were not altered under the tested conditions. PFDA was associated with increases in phosphorylated RIP3 and phosphorylated MLKL, whereas PFOS increased MLKL expression without detectable RIP3 activation. Inhibition experiments further suggested that necroptosis-related signaling contributes, in part, to PFOS- and PFDA-induced endothelial injury in vascular endothelial cells. These findings suggest that PFAS-induced vascular endothelial injury depends on molecular structure and cell type, and may involve distinct necroptosis-related signaling patterns. However, it should be noted that the PFAS concentrations used in this study were higher than those typically detected in environmental and human exposure settings. Full article

Chromium is an environmental pollutant with high toxicity and carcinogenicity. It can induce severe oxidative stress and DNA damage after entering the human body through the food chain. As a plant growth-promoting rhizobacterium (PGPR) with both heavy metal tolerance and plant growth-promoting properties, Klebsiella variicola has considerable potential for the remediation of chromium contamination. In this study, chicory served as the experimental plant to explore the mitigating impacts of K. variicola on stress induced by hexavalent chromium (Cr(VI)) at a concentration of 400 mg/kg. The results showed that chromium severely inhibited the growth of chicory. In contrast, K. variicola significantly reduced the soil chromium content. As the chromium content decreased, the activities of soil urease, sucrase, catalase, and alkaline phosphatase were restored, increasing by 32.60–53.69%. Accordingly, the contents of total phosphorus, available phosphorus, total nitrogen, available nitrogen, soil organic carbon, and available potassium also increased by 34.71–51.81%. In addition, K. variicola reversed the decline in microbial diversity induced by chromium stress, promoted the growth of beneficial bacteria such as Acidobacteriota and Chloroflexota, and enhanced the stability of soil ecosystem functions. Ultimately, the growth inhibition of chicory caused by chromium stress was alleviated, with fresh weight, root length, maximum leaf width, maximum leaf length, plant height, and stem diameter significantly increasing by 21.89–61.60%. This study enhances our comprehension of the various functions of PGPR when exposed to heavy metal stress, and provides support for the development of microbe–plant combined strategies in the remediation of chromium-contaminated soils. Full article

Aliphatic diamines possess two amino functional groups and exhibit diverse chemical properties and tunable molecular structures. By selecting the guest [(C₂H_2n+4N₂), n = 2–6] and host 18-crown-6, and controlling the design and assembly processes via modulation by thiocyanate and a manganese salt, a series of dumbbell-shaped crown ether complexes, (C₂H_2n+6N₂)²⁺(18-crown-6)₂[Mn(NCS)₄]²⁻·(δ_n,₂C₂H₃N), n = 2–6, (1)–(5), was synthesized and analyzed by single-crystal X-ray diffraction (SCXRD) at 100 K and 293 K. Variable-temperature infrared and XRD analyses confirmed that compounds 3 and 5 underwent a phase transition. As the length of the carbon chain increases and alternates between odd and even, the interplanar dihedral angle of the crown ether exhibits a distinct pattern: Even-number chains arrange in parallel, whereas odd-number chains form a pronounced angle. This structural pattern influences macroscopic deformation of the crystal and induces corresponding periodic variations in the dielectric and electrochemical properties. The wide-bandgap insulators and magnetic properties are primarily governed by the inorganic components of the system and are less influenced by the organic portion. This study reveals principles for regulating supramolecular conformation and functional properties through the parity of the organic chain lengths, providing a strategy for the molecular-level design of supramolecular crystal materials with ordered structures and tunable properties. Full article

Per- and polyfluoroalkyl substances (PFAS) are persistent chemicals with substantial bioaccumulation potential, but their distribution between blood and urine in humans remains poorly characterized. In this review, we assessed the urine-to-blood concentration ratio (UtBCR) as a potential indicator of PFAS bioaccumulation by integrating evidence from human biomonitoring studies and protein-binding data. We summarized PFAS concentrations in human serum and urine across general and highly exposed populations and identified clear compound-specific differences in blood–urine partitioning. We further examined the associations of UtBCR with carbon chain length, biological half-life, and binding-related parameters for human serum albumin (HSA), liver fatty acid-binding protein (L-FABP), and several renal transporters. Pairwise correlation analysis and partial least squares regression indicated that UtBCR was closely associated with major toxicokinetic determinants, particularly protein-binding affinity, carbon chain length, and biological half-life. Parameters related to FABP, HSA, urate transporter 1 (URAT1), and organic anion transporter 4 (OAT4) showed more consistent associations with UtBCR than those related to organic anion transporters 1(OAT1) and organic anion transporter 3 (OAT3), suggesting that plasma/tissue binding and tubular reabsorption may contribute more than active tubular secretion to PFAS blood–urine partitioning. Overall, UtBCR appears to be a useful toxicokinetic metric for comparing the relative bioaccumulation potential of PFAS. Full article

Imidazole-based ionic liquids hold immense potential in the field of mineral flotation due to their tunable properties. In this study, three imidazole-based ionic liquids with varying carbon chain lengths (OMB, DMB, and HMB) were selected as collectors for quartz flotation to systematically investigate the microscopic mechanisms by which carbon chain length influences the agglomeration and flotation behavior of quartz. Flotation tests and online particle-bubble monitoring (PBM) results indicate that the elongation of the collector’s carbon chain significantly enhances its collecting ability and reduces the required reagent dosage. To achieve the complete recovery of quartz in a neutral system, a dosage of 35 mg/L is required for OMB, whereas HMB requires only 8 mg/L. As the carbon chain lengthens, the optimal pH range for highly efficient flotation shifts from alkaline to neutral-acidic. Interfacial measurements and mechanistic analyses (Zeta potential and FTIR spectroscopy) confirm that the imidazole ring of the collector physically adsorbs onto the quartz surface through the synergistic action of electrostatic forces and hydrogen bonding, thereby inducing the hydrophobic agglomeration of particles. Notably, in a strongly alkaline system (pH = 11), the long-chain HMB promotes the formation of oversized quartz agglomerates. This leads to a depletion of free reagents in the liquid phase and destabilizes the bubble liquid film, ultimately triggering a sharp decline in recovery. Density functional theory (DFT) calculations further corroborate the structure–activity relationship at the molecular level: the extension of the carbon chain increases the highest occupied molecular orbital (HOMO) energy and electron-donating ability. The adsorption energy of HMB on the quartz (001) surface reached −350.2 kJ/mol, exhibiting the strongest solid–liquid interfacial affinity. This study elucidates the competitive mechanism of carbon chain length in regulating electrostatic adsorption, hydrophobic agglomeration, and froth stability, providing a solid theoretical foundation for the molecular design of novel green flotation reagents for quartz. Full article

The performance of a sequencing batch biofilter granular reactor (SBBGR), followed by a dual media granular activated carbon (GAC) column, was evaluated in terms of its ability to remove selected per- and polyfluoroalkyl substances (PFAS) from landfill leachate. The results show that the SBBGR achieved an overall reduction of 51%, with the preferential removal of long-chain PFAS, while short-chain PFAS were only partially removed. Subsequent GAC treatment exhibited compound-specific breakthrough behavior, which was governed by chain length. Short-chain PFAS (e.g., perfluorobutanoic acid) exhibited rapid bed volumes at 50% breakthrough (BV₅₀ ≈ 88), whereas long-chain PFAS (e.g., perfluorooctanoic acid and perfluorooctanesulfonic acid) were substantially more retained (BV₅₀ ≈ 446 and 361, respectively), with perfluorohexanesulfonic acid and perfluorodecanoic acid failing to reach BV₅₀ within the monitored period. Mass balance analysis showed that the hybrid GAC column captured ~73% of the influent PFAS mass. This resulted in >80–95% retention of long-chain PFAS and <40% retention of short-chain PFAS. Although long-chain PFAS were preferentially adsorbed, mobile short-chain species dominated residual effluent loads. These findings highlight the need for optimized contact times or dual-media strategies to control the breakthrough of short-chain PFAS. Full article

Perfluoroalkyl carboxylic acids (PFCAs) are persistent contaminants increasingly subjected to regulatory restrictions. To date, their effects on terrestrial plants remain poorly investigated. To address these knowledge gaps, a comparative assessment was conducted to identify the most sensitive plant species and the most responsive early-growth endpoints. Five PFCAs were selected according to their carbon-chain length (from 3 to 8 C-atoms). Seven plant species were exposed to a wide range of concentrations (from 0.01 up to 100 µg kg⁻¹). Germination and root elongation were evaluated as developmental endpoints to assess both acute and sublethal effects. Across species, germination exhibited weak responses, whereas root elongation appeared to be the most sensitive screening parameter, displaying divergent species-specific patterns. Notably, Sinapis alba and Cucumis sativus emerged as the most responsive species, although they exhibited opposite responses. While mustard exhibited low-dose root stimulation, cucumber showed root inhibition. Interestingly, species within the same family (Brassicaceae and Cucurbitaceae) showed contrasting sensitivity, suggesting that PFCA phytotoxicity is species-specific rather than driven by taxonomic relatedness. This divergent pattern may be linked to distinct morpho-physiological traits, supporting their use as suitable model organisms for phytotoxicity screening of PFCAs. Full article

Background/Objectives: Amyotrophic Lateral Sclerosis (ALS) is a rare, neurodegenerative disease with complex genetic and environmental determinants. The MTHFR C677T (rs1801133) variant, known for reducing enzymatic activity in the folate cycle, has been implicated in ALS risk, though findings remain inconsistent across diverse populations. Methods: A population-based case–control study was conducted in 248 age-matched individuals to investigate the MTHFR C677T (rs1801133) and ALS susceptibility. Molecular analysis was performed using the polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP). Genetic associations were evaluated under multiple inheritance models, while survival analysis utilized the Kaplan–Meier method to assess the relationship between MTHFR genotypes and patient prognosis. Results: The C677T variant showed a significant association under the codominant and recessive models, suggesting involvement in ALS risk (OR = 4.63; p = 0.01 and OR = 3.92; p = 0.02), respectively. However, stratification by sex demonstrated an association predominantly in women (OR = 7.10, p = 0.02; OR = 5.87, p = 0.04). Additionally, Kaplan–Meier analysis revealed a numerically shorter mean survival time for the mutant genotype compared with wild-type and heterozygous carriers, without statistical significance. Conclusions: Notably, we identified a significant association between the MTHFR C677T (rs1801133) variant and ALS risk, particularly among women. These findings suggest that the mutant (T/T) genotype showed a stronger association, potentially reflecting postmenopausal hormonal influences on one-carbon metabolism and related susceptibility pathways. Full article

Background: The overuse of traditional antimicrobial agents has accelerated the global spread of drug-resistant bacteria, posing a severe threat to global public health. Methods: In this work, a series of lipopeptides with varying fatty acid chain lengths were designed using the targeting antimicrobial peptide CL5 as the parental peptide. A variety of technical methods, including spectroscopic techniques, electron microscopy and computer simulation, were adopted to explore the self-assembly properties of the lipopeptides and their antimicrobial properties against Gram-positive and Gram-negative bacteria. Results: The results showed that lipopeptide self-assembly could be triggered by fatty acid chain modification with a carbon chain length exceeding 8 atoms, and hydrophobic interactions between fatty acid chains were the primary driving force for this process. The geometric mean of the minimum inhibitory concentrations of the lipopeptides exhibited an approximate “U”-shaped correlation with the length of the fatty acid chains. Among these lipopeptides, C8CL5–C12CL5 exhibited broad-spectrum and highly potent antimicrobial activity, with geometric means of 6.20, 5.16, and 8.00 μM against all tested bacteria, and selectivity index values of 12.26, 8.14, and 7.48, respectively. Furthermore, the lipopeptides exhibited high selectivity, rapid time-killing kinetics, as well as excellent thermal, pH and salt stability. Mechanistic studies revealed that the lipopeptides exerted antimicrobial effects through multiple pathways: disrupted bacterial cell membranes and caused the leakage of cellular contents, bound to bacterial genomic DNA, and promoted the production of reactive oxygen species. Conclusions: Collectively, lipopeptides modified with appropriate fatty acid chains exhibit broad-spectrum and highly effective antimicrobial activity, making them promising alternatives to traditional antibiotics for the treatment of bacterial infections. Full article

Coal gasification fine ash (CGFA) is a carbon–mineral composite solid waste whose valorization is severely hindered by poor interfacial compatibility with organic media due to its highly polar surface. Here, we report a surface alkylation strategy using haloalkanes with variable chain lengths to systematically tune the surface chemistry and thermo-oxidative behavior of CGFA. Comprehensive spectroscopic characterizations (XPS, FTIR, and ¹³C NMR) confirm successful grafting of alkyl chains, which increases aliphatic C-H content from 24.8% to 43.9% while reducing polar carboxyl groups from 7.9% to 1.6%, with the mineral framework remaining intact. Thermogravimetric analysis reveals that alkylation lowers the onset decomposition temperature from 358 °C to 295 °C and enhances the maximum mass-loss rate. Kinetic analysis shows that grafted alkyl chains act as low-energy initiation sites, reducing the initial activation energy to 95 kJ/mol, while the later-stage oxidation becomes diffusion-limited. Notably, long straight-chain alkylation achieves the best performance, whereas branched chains are less effective due to steric hindrance and pore blockage. This work establishes a clear chain-length-dependent structure–thermal response relationship, positioning alkylated CGFA as a designable precursor for functional carbon materials, intelligent char-forming agents, and tunable components for energy or responsive material systems. Full article

The growing penetration of electric logistics vehicles (ELVs) poses a significant challenge to electric utility site selection. This paper addresses the problem of joint site selection for electric logistics vehicle charging and swapping stations (CSSs). First, a joint site selection model is introduced to characterize the problem, and an improved genetic algorithm (IGA) is designed to solve this model. Derived from the standard genetic algorithm (SGA), the IGA incorporates local search operations, evolutionary inversion operations, and an elitist preservation strategy to enhance performance. On this basis, small-scale numerical simulations are conducted to determine the optimal parameters, thereby guaranteeing optimal algorithmic efficiency. Subsequently, large-scale numerical simulations are performed, with key indicators recorded including the optimal routing length, battery replenishment frequency, number of stations, number of ELVs, and solution time. Finally, analysis across three efficiency levels demonstrates that joint siting improves distribution efficiency by 39.38%, increases grid electricity sales by 46.89%, and reduces total transportation costs by 26.28%, with the optimization scheme validated across six different numerical scenarios. Overall, the joint site selection proposed in this paper has enhanced the benefits of relevant stakeholders and provided a reference for building a low-carbon transportation chain. Full article

In this work, the ability of a series of imidazolium-based ionic liquids (ILs) to depolymerize Kraft lignin through acid hydrolysis was evaluated. ILs featuring two-, four-, and six-carbon alkyl chains combined with [Cl⁻], [BF₄⁻] and [CH₃COOH⁻] anions were studied to determine the influence of cation and anion structure. The twelve ILs were synthesized and characterized by FT-IR and ¹H/¹³C NMR spectroscopy. Results indicate that both the anion and cation significantly affect depolymerization efficiency; specifically, longer alkyl chain lengths correlated with higher conversion percentages. Anion efficacy followed the order: [Cl⁻] > [CH₃COOH⁻] > [BF₄⁻]. Furthermore, reaction temperature did not show a significant impact on conversion within the studied range. Spectroscopic data suggest that bond dissociation follows a Brønsted acid-catalyzed mechanism, evidenced by the reduction of phenolic components and guaiacyl/syringyl units in the recovered lignin samples. Full article