Search Results (178)

Traditional polysaccharide extraction suffers from low efficiency and high energy consumption, while deep eutectic solvents (DESs) are promising sustainable solvents. This study used DES ChCl-LA (1:2) with ultrasonic assistance to extract polysaccharides from red alga A.taxiformis. Optimized via single-factor experiments and response surface methodology (350 W, 1:30 g/mL, 75 °C), the yield reached 11.28% ± 0.50% (1.5 times higher than that obtained by water extraction). Structural characterization revealed that the DES extract was an acidic polysaccharide, mainly composed of galactose (89.2%), glucose (4.9%), xylose (4.9%), and glucuronic acid (1.0%), with a weight-average molecular weight of 99.88 kDa. Density functional theory and molecular dynamics simulations showed that ChCl-LA enhanced galactose solubility via stronger hydrogen bonding (−25.33 vs. −5.06 kcal/mol for water). Notably, the immunological activity of the DES-extracted polysaccharide was significantly compromised compared to the water-extracted counterpart (p < 0.05). At a concentration of 0.25 mg/mL, the water-extracted polysaccharide-treated group exhibited a 33.98% higher neutral red phagocytosis rate in macrophages, a nitric oxide (NO) secretion level of 34.14 μmol/L (94.98% higher) compared with the DES-extracted polysaccharide group, as well as significantly higher secretion levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). The observed disparity in bioactivity is likely due to the distinct chemical profiles resulting from the two extraction methods, including the significantly reduced molecular weight and potential alterations of sulfation degree, monosaccharide composition, and protein content in the DES-extracted polysaccharide. This mechanistic perspective is supported by the relevant literature on the structure–activity relationships of polysaccharides. This study demonstrates the potential of ChCl-LA and elucidates the complex effects of extraction methods on polysaccharide’s structure and function, thereby informing the high-value utilization of A. taxiformis in functional foods. Full article

During orbital service, precision aerospace equipment is frequently subjected to harsh vibration environments that can significantly affect reliability and service life. Consequently, the development of effective vibration isolation technologies has become a crucial aspect of aerospace structural design. In this study, random vibration theory and frequency-domain analysis methods were employed to investigate the dynamic response characteristics of a symmetrical frustum-shaped metal rubber (FSMR) isolation device under complex operating conditions. The influence of metal rubber density, spring stiffness, and input vibration level on its isolation performance was systematically examined. This work presents the first systematic experimental investigation into the nonlinear dependencies of the performance of a symmetrical frustum-shaped metal rubber isolator on multiple parameters (density, stiffness, excitation level) under random vibration. The test results show that under identical excitation conditions, the device achieves optimal damping ratio and isolation efficiency (59.71%) when the metal rubber density is 2.0 g/cm³. A moderate increase in spring stiffness reduces the resonance peak and improves stability, with a stiffness of 100 kN/m exhibiting the best overall performance. In addition, higher input vibration levels markedly elevate the acceleration response and the resonant peak amplification factor of the isolator, demonstrating that high-intensity excitation magnifies the vibration response and degrades the isolation efficiency. Full article

Hexakis(4-(4-carboxylphenyl)phenyl)benzene, H₆cbb, was used to prepare the rod-based metal–organic frameworks (rod-MOFs) [Mn₄(cbb)(dmf)₂(OAc)₂] CTH-50 and [Gd₃(cbb)(dmf)₂(H₂O)(OAc)₃] CTH-51 by solvothermal synthesis (dmf = N,N-dimethylformamide) with single crystal diffraction revealing that CTH-50 (by X-ray) and CTH-51 (by electron diffraction) can be described as 5- and 6-connected yav-nets. Gas sorption analysis gave a BET surface area of 787 m²/g for CTH-50 and 187 m²/g for CTH-51, with CTH-50 having an Ideal Adsorbed Solution Theory (IAST) selectivity for SF₆ of 35 at 10 kPa, and thermogravimetry indicated the possible stability of CTH-50 to 300 °C and CTH-51 to 400 °C. Full article

Molten salt, as a phase change heat storage material, can be used to mitigate the volatility of clean energy. Increasing the specific heat of molten salts can help to increase heat storage density and reduce costs. In this study, nanoparticles with different potentials were prepared and doped into Solar Salt (NaNO₃-KNO₃). The modification results of the nanoparticles were evaluated by transmission electron microscopy, energy dispersive X-ray spectroscopy and infrared spectroscopy, and the modification process was analyzed by density functional theory. The specific heat, thermal diffusion coefficient, melting point, latent heat of the composites and their variation mechanism were analyzed using synchronized thermal analyzer, laser flash analyzer and scanning electron microscope. It was found that acidification was able to modify the SiO₂ nanoparticles and that the higher the acidity, the more the negative charge of the nanoparticles was neutralised. A 25.8% decrease in zeta potential to −23.17 mV was observed for the nano-SiO₂ after treatment with HCl at pH 1, compared to the non-acidified sample. The microelectric field generated by the charged nanoparticles affects the thermophysical properties such as the specific heat of the molten salt-nanoparticle composites, with one of the samples having the largest specific heat (1.79 J/(g·K)) and thermal diffusion coefficient (0.94 mm²/s), which were increased by 13.3% and 14.6%, respectively, compared to the Solar Salt. This study attributes the alterations in thermophysical properties to the variation in ion separation distance induced by the charge on nanoparticles. Full article

Understanding the molecular determinants of antioxidant activity in natural phenolic compounds is essential for explaining their biological performance and designing new radical scavengers. In this work, the radical-scavenging mechanisms of three major ginger phenolics—6-gingerol (GIN), 6-shogaol (SHO), and 6-paradol (PAR)—were systematically investigated using density functional theory (DFT) thermochemistry at the M06-2X/6-31+G(d,p) level in the gas phase, benzene, and water. Three canonical pathways—hydrogen atom transfer (HAT), single-electron transfer followed by proton transfer (SET–PT), and sequential proton loss–electron transfer (SPLET)—were evaluated through full optimization and frequency calculations at 298.15 K, combined with the SMD solvation model. Frontier molecular orbital (FMO), molecular electrostatic potential (MEP), and quantum theory of atoms in molecules (QTAIM) analyses were employed to correlate electronic structure with reactivity. The results reveal a distinct solvent-dependent mechanistic crossover. In the gas phase and benzene, the low dielectric constant suppresses charge separation, making HAT the thermodynamically dominant pathway. In water, strong stabilization of ionic species lowers both the ionization and deprotonation barriers, allowing SPLET and SET–PT to become competitive or even preferred. Across all media, the phenolic O–H group is the principal reactive site, while the aliphatic O–H of GIN remains inactive. SHO exhibits the most versatile redox profile, combining a highly conjugated α,β-unsaturated chain with favorable charge delocalization; PAR is somewhat less redox-active, while GIN shows intermediate performance governed by intramolecular hydrogen bonding. The assembled thermodynamics for HOO• scavenging confirm that all three phenolics are thermodynamically competent antioxidants (ΔG° ≈ −4 kcal mol⁻¹ in water), with comparable driving forces; electronic descriptors indicate SHO is the most redox-flexible, GIN(phenolic) is moderately and PAR is somewhat less charge-transfer-prone, while GIN(aliphatic) remains inactive. These findings provide a comprehensive structure-to-mechanism correlation for ginger phenolics and establish a predictive framework for solvent-controlled antioxidant behavior in phenolic systems. Full article

To address the limitations of traditional groundwater quality assessment and prediction methods, this study integrates game theory and machine learning to investigate the drinking quality of groundwater in the southwestern Qinghai–Tibet Plateau. The results showed that the groundwater in the study area is generally weakly alkaline (mean pH: 8.08) and dominated by freshwater (mean TDS: 302.58 mg/L), with hardness levels mostly ranging from soft to medium. Major cations follow the concentration order: Ca²⁺ > Na⁺ > Mg²⁺ > K⁺; anions are in the sequence of HCO₃⁻ > SO₄²⁻ > Cl⁻. The hydrochemical type is mainly Ca-HCO₃. A few samples exceed the limit values specified in the Groundwater Quality Standard. Through multivariate statistical analysis, ion ratio analysis, and saturation index calculations, water-rock interaction is identified as the primary factor influencing groundwater chemistry. It consists of carbonate dissolution and silicate weathering, accompanied by cation exchange. The water quality index improved based on game theory, integrated subjective weights (from analytic hierarchy process) and objective weights (from entropy-weighted method), shows that the overall groundwater quality in the study area is good: 95.97% of the samples are high-quality water (WQI ≤ 50), more than 99% of the samples have a WQI < 150, which is suitable as drinking water sources; only 0.81% of the samples are of extremely poor quality, presumably related to local pollution. Linear regression achieved the best performance (R² = 0.99, RMSE≈0.00) with strong stability, followed by support vector machines (test R² = 0.98), while the extreme gradient boosting model showed overfitting. This study provides a scientific basis for groundwater management in river basins. Full article

Rape is one of the most widely cultivated and highest-yielding fruit crops in the world. However, research on its precise nutrient diagnosis and fertilization theory is severely lacking, significantly restricting the development of the grape industry. In this study, an L₁₆(4⁵) orthogonal experimental design was applied to determine the effects of varying ratios of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) on the fruit quality of ‘87-1’ grape (Vitis vinifera L.) cultivated in a facility, aiming to optimize nutrient application rates and improve fruit quality. Among the treatments T5 (N2P1K2Ca3Mg4), T14 (N4P2K3Ca1Mg4), and T9 (N3P1K3Ca4Mg2), treatment T9 had the most significant effect on single fruit weight, total soluble solids (TSS) content, fruit firmness (FF), and fruit quality index (FQI) and was conducive to the positive accumulation of the above quality indicators. Based on a comprehensive multi-factor analysis of variance, the optimal fertilization combination for achieving a high FQI was N3P1K2Ca1Mg2, corresponding to application rates of 375.0, 0, 168.8, 0, and 70.5 kg·hm⁻² for N, P₂O₅, K₂O, CaO, and MgO, respectively. Furthermore, to establish standards for multivariate compositional nutrient diagnosis (CND) and define the nutrient sufficiency range for ‘87-1’ grape fruit cultivated in a facility, the nutrient concentrations in various plant tissues and the soil and the FQI were measured across 80 treatments over five consecutive years. The nutritional status of the grapes cultivated under these treatments was calculated using the Technique for Order Preference by Similarity to Ideal Solution and the CND method. Based on the optimal nutrient ranges for high FQI sub-populations, a precise fertilization model was developed to facilitate economic fertilizer savings, quality improvement, and standardized grape cultivation in a facility. Full article

The Ti6Al4V alloy is considered the most beneficial of the titanium alloys for use in biomedical applications. However, it corrodes when exposed to various biocompatible fluids. This investigation aims to evaluate the corrosion inhibition performance of the Ti6Al4V in a saline solution (SS) using thiocolchicoside (TCC) drug as an environmentally acceptable corrosion inhibitor. The corrosion assessments were conducted using potentiodynamic polarization curves (PPCs), open-circuit potential (OCP), and electrochemical impedance spectroscopy (EIS) methodologies, supplemented by scanning electron microscopy (SEM), energy-dispersive X-ray (EDS) analysis, atomic force microscopy (AFM), and contact angle (CA) measurements. The outcomes indicated that the inhibitory efficacy improved with higher TCC concentrations (achieving 92.40% at 200 mg/L of TCC) and diminished with an increase in solution temperature. TCC’s physical adsorption onto the surface of the Ti6A14V, which adheres to the Langmuir adsorption isotherm, explains its mitigating power. The TCC acts as a mixed-type inhibitor. The adsorption and inhibitory impact of TCC were examined at various temperatures using PPC and EIS. When TCC is present, the corrosion’s apparent activation energy is higher (35.79 kJ mol⁻¹) than when it is absent (14.46 kJ mol⁻¹). In addition, the correlation between the structural properties of thiocolchicoside (TCC) and its corrosion inhibition performance was systematically analyzed. Density Functional Theory (DFT) calculations were utilized to characterize the adsorption mechanism, supported by Natural Bond Orbital (NBO) analysis and Molecular Dynamics (MD) simulations. The combined computational and electrochemical findings confirm that TCC provides effective and enhanced corrosion protection for the Ti6Al4V alloy in a saline environment. These characteristics provide compelling evidence for the suitability of these pharmaceutical compounds as promising corrosion inhibitors. Full article

Density functional theory (DFT) calculations at the M06-2X-D3/6-311++G(2df,2pd) level elucidate the mechanism and selectivity origins in the NHC-catalyzed divergent synthesis of spirocyclopentane oxindoles from isatin-derived enals and N-sulfonyl ketimines. The Michael addition constitutes the regio- and stereoselectivity-determining step, where Parr function analysis demonstrates that nucleophile/electrophile electrophilicity governs regioselectivity, while distortion/interaction and non-covalent interaction analyses reveal stereoselectivity is controlled by distortion and weak interactions. K₃PO₄ facilitates Breslow intermediate formation and proton transfer toward the β-lactam-fused spirocyclopentane oxindole, whereas N,N-diisopropylethylamine (DIPEA) promotes these processes for the spirocyclopentane oxindole bearing an enaminone moiety. Catalyst roles are also further delineated. Full article

The development of advanced drug delivery systems is essential for improving therapeutic efficacy, particularly in the treatment of neurodegenerative disorders such as Alzheimer’s disease. This study investigates zinc-modified mordenite zeolite (MR-ZN) as a novel platform for the controlled delivery of donepezil (DPZ), a cholinesterase inhibitor. Natural mordenite was modified with zinc, enhancing its surface area from 62.1 to 85.4 m²/g and improving its adsorption properties. Donepezil was successfully loaded at two doses (10 mg and 23 mg), achieving high loading efficiencies of 95% and 94%, respectively. Adsorption kinetics followed a pseudo-second-order model (R² > 0.99), indicating that chemisorption predominates through coordination between DPZ functional groups and Zn²⁺ sites, while complementary physisorption via hydrogen bonding and van der Waals interactions also contributes to molecular stabilization within the zeolite framework. In vitro release studies under simulated gastrointestinal conditions demonstrated sustained and pH-responsive release profile with 80% and 82% of donepezil released after 24 h for 10 mg and 23 mg formulations, respectively. Density Functional Theory (DFT) calculations revealed favorable adsorption energy (−26.4 kJ/mol), while Bader and Electron Localization Function (ELF) analyses confirmed hydrogen bonding and electrostatic interactions without compromising the zeolite framework. These findings validate MR-ZN as structurally stable, efficient, cost-effective and biocompatible matrix for oral drug delivery. The combination of experimental data and theoretical modeling supports its potential to improve bioavailability and therapeutic performance in neurodegenerative treatment. Full article

Coastal Bangladesh faces severe drinking water scarcity due to salinity intrusion. To address this challenge, the study assesses the socio-technical and economic factors shaping the performance of small-scale reverse osmosis (RO) desalination plants through field audits, household surveys, stakeholder interviews, and water quality analysis. Community acceptance was evaluated using the Theory of Planned Behavior (TPB). Feedwater was highly contaminated, with average TDS 3732.63 mg/L, hardness 636.36 mg/L, iron (Fe) 3.23 mg/L, and turbidity 14.63 NTU. Despite this, RO systems demonstrated strong performance, achieving removal efficiencies of 95.15% for salts, 95.95% for hardness, and 91.67% for alkalinity, with an average recovery rate of 37.25% (range: 20–60%). Treated water met WHO and Bangladesh standards, with mean concentrations of TDS (195.54 mg/L), Fe (0.21 mg/L), arsenic (0.0085 mg/L), and turbidity (1.09 NTU). However, inadequate operator training and a lack of maintenance threaten sustainability. Energy consumption increased by 0.1 kWh/m³ per 1000 mg/L rise in salinity, while financial constraints hinder membrane replacement. TPB analysis revealed positive attitudes and perceived behavioral control as key adoption drivers. Untreated brine discharge (mean TDS 12,900 mg/L) posed significant environmental risks. This study provides micro-level insights to inform policy and strengthen the sustainability of decentralized RO systems in climate-vulnerable coastal regions. Full article

This study investigated the structure of vegetation communities in Yongneup, a representative montane peatland on Mt. Daeamsan, Korea. It also identified key microenvironmental drivers shaping their distribution. We surveyed 200 quadrats, analyzing herbaceous plant composition alongside peat depth, water level, and soil chemical properties. Multivariate analyses, including cluster analysis and classification tree analysis (CHAID), identified nine distinct vegetation communities. Each community was correlated with specific environmental gradients. Dominant species included Sanguisorba tenuifolia and Carex thunbergii var. appendiculata, with rare species such as Carex chordorrhiza and Drosera rotundifolia present in localized habitats. Peat depth emerged as the primary determinant of vegetation distribution, followed by hydrology and nutrient levels, including phosphorus and cations (Mg²⁺, Na⁺, K⁺). Our results underscored continuous ecological gradients rather than discrete zonation, aligning with ecological continuum theory. These findings provide a robust scientific framework for ecological monitoring and restoration. They also support Korea’s national wetland conservation policies and international commitments such as the Ramsar Convention. Full article

Monitoring the time-dependent rheological properties of 3D printed MgO-SiO₂-K₂HPO₄ is critical for optimizing the dynamic structural reconstruction ability. The collaborative analysis for the contribution of colloidal force based on EDLVO theory and the volume fraction of K-struvite (MgKPO₄·6H₂O) was conducted. Results showed that 20% silica fume (SF) was identified as the optimal content to achieve balanced rheo-mechanical performance (28 d compressive strength = 113.63 MPa, dynamic yield stress = 359.98 Pa, thixotropic area = 2.14 × 10⁴ Pa/s). The static yield stress development within 50 min exhibited two distinct stages: the initial rapid linear growth stage (Stage I, 5–30 min) dominated by colloidal forces (R² = 0.81 at 20% SF), followed by the slow increased plateau (Stage II, 30–50 min) correlated with K-struvite volume fraction. Also, dual crystallization pathways of K-struvite included direct precipitation from supersaturated Mg²⁺, K⁺, PO₄³⁻ ionic species and transformation from potassium-deficient phosphate phase. Quantitative results establish a predictive framework for microstructural construction, enabling precise control of structural build-up and 3D printability in MgO-SiO₂-K₂HPO₄ cementitious composites. Full article

In the present study three composite materials based on iron in combination with bismuth, copper or lithium carbonates FeNO₃@Li₂CO₃ (SFL), FeNO₃@CuCO₃ (SFC), and FeNO₃@(BiO)₂CO₃ (SFB) were synthesized by coprecipitation. The purpose was to obtain materials that possess targeted adsorbent properties for the recovery of silver ions from aqueous solutions. After synthesis, to emphasize the adsorptive qualities of materials for the recovery of silver ions, the synthesized composite materials, as well as those doped with silver ions following the adsorption process (SFL-Ag, SFC-Ag, and SFB-Ag), were characterized and several adsorption-specific parameters were examined, including temperature, contact time, pH, adsorbent dose, and the initial concentration of silver ions in solution. Subsequently, the ideal adsorption conditions were determined to be as follows: pH > 4, contact time 60 min, temperature 298 K, and solid–liquid ratio (S–L) of 0.1 g of adsorbent to 25 mL of Ag (I) solution for all three materials. The Langmuir model properly fits the experimental equilibrium data of the adsorption process; however, the Ho–McKay model closely represents the adsorption kinetics. The maximum adsorption capacities of the materials, 19.7 mg Ag(I)/g for SFC, 19.3 mg Ag(I)/g for SFB, and 19.9 mg Ag(I)/g for SFL, are comparable. The adsorption mechanism is physical in nature, as evidenced by the activation energies of 1.6 kJ/mol for SFC, 4.15 kJ/mol for SFB, and 1.32 kJ/mol for SFL. The highest Ag(I) concentration used for doping all three materials in the study was 150 mg Ag(I)/L. The process is endothermic, spontaneous, and takes place at the interface between the adsorbent and the adsorbate, according to thermodynamic theory. Subsequently, the antimicrobial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans microorganisms was evaluated by rate of inhibition assessment. The SFC-Ag material showed a percentage of 100% inhibition with respect to the positive control for each microorganism. All synthetized materials have better efficiency as antifungal agents. Full article

According to a clever but rarely quoted or acknowledged work of E. Vessiot that won the prize of the Académie des Sciences in 1904, “Differential Galois Theory” (DGT) has mainly to do with the study of “Principal Homogeneous Spaces” (PHSs) for finite groups (classical Galois theory), algebraic groups (Picard–Vessiot theory) and algebraic pseudogroups (Drach–Vessiot theory). The corresponding automorphic differential extensions are such that $di{m}_K\left(L\right)=\mid L/K\mid <\infty$, the transcendence degree $trd(L/K)<\infty$ and $trd(L/K)=\infty$ with $difftrd(L/K)<\infty$, respectively. The purpose of this paper is to mix differential algebra, differential geometry and algebraic geometry to revisit DGT, pointing out the deep confusion between prime differential ideals (defined by J.-F. Ritt in 1930) and maximal ideals that has been spoiling the works of Vessiot, Drach, Kolchin and all followers. In particular, we utilize Hopf algebras to investigate the structure of the algebraic Lie pseudogroups involved, specifically those defined by systems of algebraic OD or PD equations. Many explicit examples are presented for the first time to illustrate these results, particularly through the study of the Hamilton–Jacobi equation in analytical mechanics. This paper also pays tribute to Prof. A. Bialynicki-Birula (BB) on the occasion of his recent death in April 2021 at the age of 90 years old. His main idea has been to notice that an algebraic group G acting on itself is the simplest example of a PHS. If G is connected and defined over a field K, we may introduce the algebraic extension $L=K\left(G\right)$; then, there is a Galois correspondence between the intermediate fields $K\subset K^{\prime }\subset L$ and the subgroups $e\subset G^{\prime }\subset G$, provided that $K^{\prime }$ is stable under a Lie algebra $\Delta$ of invariant derivations of $L/K$. Our purpose is to extend this result from algebraic groups to algebraic pseudogroups without using group parameters in any way. To the best of the author’s knowledge, algebraic Lie pseudogroups have never been introduced by people dealing with DGT in the spirit of Kolchin; that is, they have only been considered with systems of ordinary differential (OD) equations, but never with systems of partial differential (PD) equations. Full article