Search Results (3,027)

This study addresses the synthesis of a new liquid crystalline compound featuring a 3,5-disubstituted isoxazoline and a 1,3-dioxolan-2-one ring, and renewable aromatic building blocks derived from vanilin and benzoic acid. The target compound was synthesized through a multistep synthetic route involving alkylation, esterification, oxime formation, and a 1,3-dipolar cycloaddition reaction. The synthesized compound, 2-methoxy-4-[5-(2-oxo-1,3-dioxolan-4-yl)-4,5-dihydroisoxazol-3-yl]phenyl 4-n-decyloxybenzoate, was isolated and fully characterized by spectroscopic techniques. Liquid crystal behavior was evaluated by DSC and POM. The monotropic mesomorphic behavior of the title compound was dictated by the interplay between molecular architecture and intermolecular organization, with the methoxy substituent and the 1,3-dioxolan-2-one ring critically influencing phase stability and texture morphology. These findings suggest a structure–property relationship and guide ongoing synthetic optimization toward achieving a stable enantiotropic liquid-crystalline phase and further ion-conduction experiments. Full article

To enhance the overall performance of direct coal liquefaction residue (DCLR)-modified asphalt, particularly its low-temperature cracking resistance, SBS and aromatic oil were employed for composite modification. Nine composite-modified asphalt formulations were prepared based on an orthogonal experimental design. High-and low-temperature rheological properties and microstructure of all modified asphalts were systematically evaluated using a dynamic shear rheometer (DSR), a bending beam rheometer (BBR), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results indicate that composite modification significantly enhanced the high-temperature performance of the asphalt. Modified asphalt labeled as Sample No. 9 (9% DCLR, 4% SBS, and 6% aromatic oil) demonstrated the minimal non-recoverable creep compliance ($J_{nr}$) value of 0.58 kPa⁻¹ at 64 °C, indicating a 78.6% decrease relative to the matrix asphalt. In terms of low-temperature performance, Sample No. 3 satisfied the Superpave cracking resistance criterion, exhibiting a creep rate ($m$-value) of 0.312 at −12 °C. It was revealed by FTIR analysis that the interaction between the composite modifier and the base asphalt was mainly physical blending, and no new functional groups were generated either before or after aging. The improvement in performance was attributed to the physical compatibility and structural reorganization among the components. Microstructural analysis revealed that the uniform dispersion of modifiers in matrix asphalt and the subsequent formation of a dense micelle structure after aging contributed to the enhanced macroscopic performance. This study provides theoretical and technical support for the high-value application of DCLR in asphalt pavements. Full article

This study evaluates the impact of the complete early leaf removal on the fruit zone for consecutive growing seasons (2023–2024) on the agronomic performance and oenological potential of the indigenous Greek red cultivar Avgoustiatis (Vitis vinifera L.), which is cultivated in Zakynthos, Greece. The defoliated treatment significantly reconfigured vine productivity, inducing a 33–34% reduction in yield during both years of the study and a contraction in berry mass, which consequently increased the skin-to-berry ratio by 30% and 60% for the 2023 and 2024 vintages, respectively. In the must, defoliation facilitated a desirable decoupling of sugar and acidity, achieving higher soluble solids while maintaining a robust acid core. Furthermore, defoliation enhanced phenolic maturity, in both vintages, increasing total anthocyanins and improving their extractability. Although extreme thermal conditions in 2024 led to lower color intensity and total phenolics in the treated wines compared to the control, the volatile profile revealed a significant reduction in herbaceous C₆ alcohols and an increase in floral terpenes like nerol. Sensory analysis confirmed that defoliated wines were characterized by lower astringency and superior aromatic typicity, with distinct notes of violet and vanilla. These findings suggest that early defoliation is a potent tool for optimizing the structural and aromatic integrity of Avgoustiatis, though its application must be adapted against Mediterranean thermal stress. Full article

This study investigated the influence of hydrocarbon feedstock composition evolved from slow pyrolysis of polypropylene (PP) and polystyrene (PS) and plasma gas flow rate on the carbon black and hydrogen production yields and quality. The temperature distribution and feedstock flow within the carbon black formation zone with plasma were supplementarily modeled using computational fluid dynamics. TG-FTIR-GC/MS was employed to analyze thermal degradation patterns of plastics and to estimate the composition of volatile intermediates of plastics’ slow pyrolysis. Produced CB was characterized, encompassing physical, structural, and compositional properties using thermogravimetric analysis, CHNS analysis, scanning electron microscopy–energy dispersive spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller, and Raman spectroscopy. The results revealed that both feedstocks yield CB with comparable structural characteristics; however, PS-derived (aromatic-rich) volatiles produce significantly higher CB yields, whereas PP-derived (aliphatic) volatiles favor hydrogen formation. Differences in carbon structure were also observed, with PP-derived CB exhibiting a higher degree of graphitic ordering compared to the more disordered CB obtained from PS. The optimal flow rate of plasma gas was identified as 6.1 L/min. Increasing the flow rate to 7.2 L/min led to reduced conversion efficiency for PP-derived long-chain hydrocarbons. Overall, the findings demonstrate the potential of this approach for the co-production of high-quality carbon black and hydrogen from plastic waste. Full article

Raman spectroscopy (RS) provides detailed information on molecular structure but remains challenging for low-scattering proteins in complex media. Myelin basic protein (MBP) is a key structural component of central nervous system myelin and a clinically relevant molecule in demyelinating disorders; however, to the best of our knowledge, its Raman signature in solution has not been reported. In this work, Raman and surface-enhanced Raman spectroscopy (SERS) were employed to characterize purified human myelin basic protein (MBP) in aqueous solution and cerebrospinal fluid (CSF). Quasi-spherical silver nanoparticles were used as SERS elements, yielding enhancement factors of 10⁵ and increasing sensitivity to MBP-associated spectral changes at low concentrations. The MBP spectrum exhibited vibrational modes primarily associated with amide II and amide III bands, as well as aromatic side-chain contributions. Comparative analysis of MBP, CSF, and MBP-spiked CSF samples revealed significant spectral overlap, limiting discrimination based solely on peak positions. To overcome this limitation, spectral correlation and band-intensity-ratio analyses were applied, revealing reproducible trends associated with increasing MBP content. While individual MBP bands are not exclusive, the observed spectral patterns demonstrate the sensitivity of RS and SERS to MBP-induced spectral changes in CSF. These findings should be interpreted as a proof-of-concept in a single-donor CSF matrix. Full article

Glaucoma remains a primary cause of blindness, yet its pathogenesis often extends beyond intraocular pressure (IOP). This review integrates four converging lines of metabolic evidence—aqueous humor (AH) metabolomics, kynurenine pathway (KP) activity, tetrahydrobiopterin (H4BIP) biology, and NAD/one-carbon dysfunction—into a testable framework for retinal ganglion cell vulnerability. By utilizing a systematic AH metabolomics atlas covering glaucoma, pseudoexfoliation, and diabetes on a standardized HILIC-LC-HRMS platform, we demonstrate that, while aromatic amino acid elevations are non-specific markers, kynurenine monooxygenase (KMO) upregulation is a condition-specific glaucoma signature. These local findings are corroborated by systemic evidence: POAG patients exhibit significant folic acid deficiency (p = 0.007) and elevated alpha-1-antitrypsin (AAT). Critically, AAT correlates inversely with both serum folate (r_s = −0.485, p < 0.001) and retinal nerve fiber layer thickness (r_s = −0.386, p = 0.017), providing the first in-patient evidence linking systemic inflammation to structural optic nerve damage. We conclude that KMO serves as a critical enzymatic node linking tryptophan metabolism, H4BIP availability, and NAD synthesis. These results characterize glaucoma as a disease of progressive cofactor failure and define a research agenda for multimodal metabolic neuroprotection. Full article

Lignin, a complex natural three-dimensional aromatic polymer, is prone to condensation during the separation process, owing to the diverse properties of its basic structural units, linkage types, and spatial configurations. These inherent structural complexities present significant challenges for its efficient isolation and precise transformation. Current separation techniques primarily include physical, chemical (such as acid hydrolysis, alkaline dissolution, organic solvents, and ionic liquids), and biological methods. Each approach offers distinct advantages and limitations in terms of yield, purity, cost, and impact on lignin structure. Studies have indicated that ionic liquids and organic solvent methods demonstrate considerable application potential owing to their mild reaction conditions and high selectivity. Future research should focus on developing green, efficient, and low-cost separation technologies, while also enhancing detailed structural characterization and targeted lignin conversion to facilitate its large-scale utilization in the production of value-added materials and chemicals. Full article

Coal liquefaction residues (CLRs), including both indirect (ICLR) and direct (DCLR) variants, represent industrial by-products whose conventional landfill disposal raises environmental concerns. This study comparatively analyzes ICLR and DCLR properties against limestone fine aggregates through physicochemical characterization. Results indicate that ICLR contains predominant SiO₂ crystalline phases (50.05%) with trace Fe-Ti-Al-Mg oxides, demonstrating higher Vickers hardness (615 HV vs. 246 HV for limestone) and elastic modulus (98 GPa vs. 81 GPa for limestone), while its apparent relative density (2.612) closely matches that of limestone (2.783). Conversely, DCLR features abundant carbonaceous components (75.9% C) with olefinic/aromatic structures (asphaltene content 66.2%), exhibiting lower mechanical strength (Vickers hardness 21 HV) but enhanced asphalt affinity, as indicated by strong C=C (1591 cm⁻¹) and aromatic C–H (744 cm⁻¹) absorption peaks in FTIR. Both CLRs share comparable gradation curves and micromorphological characteristics with limestone aggregates, including uniform surface scaly textures. While pore-size distributions differ minimally between CLRs, both present finer porosity than limestone and show no leachate toxicity risks, confirming their viability as sustainable alternatives to asphalt fine aggregates. Full article

The complete removal of persistent aromatic organic pollutants from aqueous environments demands the development of sustainable and highly efficient filtration materials. In this study, novel bio-sourced mixed-matrix membranes (MMMs) were successfully fabricated by incorporating the highly porous metal–organic framework MIL-68(Al) into a biodegradable polylactic acid (PLA) matrix via a solvent-induced phase inversion method. The integration of MIL-68(Al) nanoparticles significantly tailored the membrane’s morphological structure, endowing the hybrid membranes with enhanced surface hydrophilicity (water contact angle reduced from 90.3° to 72.7°) and superior permeability. The pure water flux reached an optimal value of 42.2 L m⁻² h⁻¹ at a 15 wt.% MOF loading. Crucially, the hybrid membranes exhibited exceptionally high adsorptive removal performance for p-nitrophenol (PNP) and methylene blue (MB). Driven by the abundant accessible active sites of the MOF filler, the MIL-20/PLA membrane achieved a maximum equilibrium adsorption capacity of 121.03 μg/cm² (36.90 mg/g) for PNP, representing a remarkable 25.7-fold enhancement over the pristine PLA membrane. Kinetic analyses confirmed that the adsorption process is strictly governed by pseudo-second-order kinetics, indicating a chemisorption mechanism dominated by hydrogen bonding and π–π stacking interactions. Furthermore, the optimized membranes demonstrated outstanding dynamic filtration efficiencies (>80%) and robust regenerability over multiple continuous operating cycles. This work not only highlights the synergistic interfacial effects between MOFs and biodegradable polymers but also provides a highly effective, eco-friendly, and sustainable membrane platform for the advanced remediation of organic-contaminated wastewater. Full article

Geranyl diphosphate synthase (GPPS) is a key enzyme in the plant isoprenoid metabolic pathway and regulates the biosynthesis of volatile monoterpenes. It plays an important role in the biosynthesis of floral volatile terpenoids (FVTs) and inter-cultivar variation in snapdragon. Despite its importance in floral scent formation, the GPPS/GGPPS gene family in snapdragon (Antirrhinum majus L.) has not been systematically characterized. In this study, nine GPPS/GGPPS family members were identified at genome-wide level. These include six AmGPPS and three AmGGPPS genes. Phylogenetic analysis grouped them into distinct subfamilies. We further analyzed their chromosomal locations, gene structures, conserved protein motifs, and promoter cis-acting elements. These results revealed both conservation and functional divergence within the gene family. To explore their functional roles, we compared gene expression profiles at the full flowering stage. This comparison was performed between strongly scented cultivar (Am3) and the weakly scented cultivar (Am5). Among all candidates, AmGPPS6 showed the most significant differential expression. Further, functional validation was conducted using transient overexpression and virus-induced gene silencing (VIGS). Overexpression of AmGPPS6 significantly increased terpenoid production. Total floral volatile terpenoids (FVTs) increased by 1.4 fold. Both monoterpene and sesquiterpene emissions were enhanced. In contrast, silencing of AmGPPS6 markedly reduced the emission of key monoterpenes such as ocimene and its isomers. Sequence analysis showed that AmGPPS6 shares 67.04% identity with canonical GPPS small subunit (GPPS.SSU). However, it lacks the conserved catalytic DDx2-D motif. This suggests that AmGGPPS2 is not catalytically active. Instead, it likely functions through heterodimer with AmGGPPS2. This interaction is supported by coordinated transcriptional expression patterns. Additionally, natural sequence polymorphisms were identified in GPPS.SSU. These variations, rather than those in GPPS.LSU, appear to drive differences in monoterpense emission between cultivars. In conclusion, AmGPPS6 in a key regulator of floral scent biosynthesis in snapdragon. This study provides new insights into functional roles of GPPS/GGPPS genes. It also offers valuable gene targets for the molecular breeding of aromatic traits in ornamental plants. Full article

Aromatic compounds derived from the shikimate (SHK) pathway constitute a diverse class of high-value molecules with applications in the pharmaceutical, food, cosmetic, and chemical industries. In microbial systems, particularly Escherichia coli, this pathway links central carbon metabolism (CCM) to the biosynthesis of L-tyrosine (L-Tyr), L-phenylalanine (L-Phe), and L-tryptophan (L-Trp), which serve as key precursors for structurally diverse metabolites. Over the past decades, metabolic engineering strategies have focused on increasing precursor availability, relieving feedback inhibition, and eliminating competing pathways. More recently, advances in synthetic biology have enabled dynamic control of metabolic flux through pathway modularization, genome-scale interventions, and regulatory circuit design. In this review, we provide a comprehensive overview of the engineering of E. coli for aromatic compound biosynthesis, highlighting key developments in the optimization of the SHK pathway and its major metabolic nodes chorismate, L-Tyr, L-Phe, and L-Trp. We examine emerging approaches, including CRISPR-based regulation, biosensor-driven dynamic control, membrane engineering, and synthetic microbial consortia. Despite significant progress, challenges related to pathway regulation, cofactor balance, metabolic burden, and product toxicity remain critical bottlenecks. Integrating metabolic engineering with synthetic biology is driving the development of programmable, scalable microbial platforms for the efficient bioproduction of aromatic compounds. Full article

This study presents the synthesis of novel heterocyclic derivatives from oxazol-5(4H)-ones and 1,2,4-triazin-6(5H)-ones classes containing the 4-chlorophenylsulfonylphenyl and arylidene motifs as potential bioactive molecules. The synthesis of new oxazol-5(4H)-ones was conducted by cyclocondensation of 2-(4-(4-chlorophenylsulfonyl)benzamido)acetic acid with several aromatic aldehydes. The reaction of oxazol-5(4H)-ones with phenylhydrazine afforded the new 1,2,4-triazin-6(5H)-ones. Spectroscopic techniques (IR, ¹H-, ¹³C-NMR, and MS) and elemental analysis were used to confirm the structures of all new compounds. The compounds were tested against Saccharomyces cerevisiae, and cells lacking the BLH1 gene were more susceptible to compound toxicity. Moreover, the compounds increased bleomycin toxicity against yeast cells. Structural similarity analysis against the ChEMBL database and approved drugs from DrugBank was performed to evaluate the structural novelty of the synthesized compounds and to obtain preliminary information regarding their potential pharmacological profiles. Full article

This review analyzes the advances over a five-year period in the development of polymeric sorbents for the purification of aqueous media from key classes of pollutants: hydrocarbons (crude oil, diesel fuel), organic dyes, pharmaceuticals (antibiotics), pesticides, herbicides, volatile organic compounds, and polycyclic aromatic hydrocarbons. Attention is paid to the analysis of structure-property-performance relationships, with an emphasis on comparing materials derived from renewable natural feedstocks (such as cellulose, chitosan, terpenes, vegetable oils, and aloe vera) with synthetic polymers. The analysis reveals that biopolymer-based sorbents exhibit comparable or superior sorption capacities combined with environmental safety, biodegradability, and low cost. The key sorption mechanisms include physical adsorption, hydrophobic interactions, and electrostatic interactions. Despite persisting challenges related to scalability, stability in real-world environments, and the need for efficient regeneration protocols, a convergent approach that combines the advantages of modified natural polymers and functional synthetic components appears to be the most promising strategy for developing cost-effective and sustainable technologies for the restoration of water quality. Full article

Background/Objectives: The widespread emergence of chloroquine-resistant Plasmodium falciparum continues to drive the search for new quinoline-based antimalarial agents capable of retaining efficacy against resistant parasites. This study aimed to evaluate a series of synthetic quinoline derivatives incorporating arylnitro and aminochalcone moieties for their antiplasmodial activity and selectivity. Methods: A series of eighteen synthetic quinoline derivatives were evaluated for in vitro antiplasmodial activity against P. falciparum strains (3D7, K1, and Dd2), along with cytotoxicity in mammalian cells and hemolytic activity in human red blood cells. Structure–activity relationship analysis was performed, and molecular docking studies were conducted against β-hematin and the chloroquine resistance transporter (PfCRT). Results: Several compounds exhibited sub-micromolar activity against the chloroquine-sensitive 3D7 strain. The most potent compound (Compound 14), a nitro-substituted N-alkylated quinoline bearing a CF₃-enriched aromatic chalcone framework, demonstrated high potency and selectivity (IC₅₀ = 0.13 μM; SI = 1132.92). Importantly, this compound retained substantial activity against multidrug-resistant K1 and Dd2 strains, displaying lower resistance indices than chloroquine. Structure–activity relationship analysis revealed that nitro substitution, N-alkylation, and halogen/CF₃-rich aromatic features critically influence potency and selectivity. Docking studies suggested that Compound 14 engages both β-hematin and PfCRT more extensively than chloroquine. Conclusions: These findings identify Compound 14 as a promising lead scaffold for further optimization toward next-generation antimalarial agents. Full article

Rotational isomers (rotamers) of substituted aromatic molecules exhibit distinct physicochemical properties that are fundamental to understanding their reactivity and biological functions. However, resolving individual rotamers spectroscopically remains challenging due to their similar transition energies and overlapping spectral features. Herein, we report the conformer-specific identification and characterization of three stable rotamers of m-ethoxyphenol using a combination of resonance-enhanced multiphoton ionization (REMPI), hole-burning (HB) spectroscopy, and mass-analyzed threshold ionization (MATI) techniques, complemented by high-level quantum chemical calculations at the B3PW91/aug-cc-pVTZ and G4 levels of theory. The S₁ ← S₀ electronic origins of rotamers I, IV, and III were determined to be 35,966 ± 2, 36,031 ± 2, and 36,198 ± 2 cm⁻¹, respectively, while their corresponding adiabatic ionization energies (IEs) were precisely measured as 64,574 ± 5, 64,122 ± 5, and 64,994 ± 5 cm⁻¹. The vibrational spectra of both the S₁ excited state and the D₀ cationic ground state were assigned, with most active modes corresponding to in-plane benzene ring vibrations. Structural analysis reveals that the benzene ring undergoes slight expansion upon S₁ ← S₀ excitation and contraction upon D₀ ← S₁ ionization, while the overall molecular geometry remains remarkably similar across all three electronic states, a key factor underlying the excellent agreement between experimental and simulated Franck–Condon spectra. Comparison with m-methoxyphenol demonstrates that the stronger electron-donating ability of the ethoxy group leads to systematically lower excitation and ionization energies. The distinct spectroscopic fingerprints established herein provide a definitive reference for identifying specific m-ethoxyphenol rotamers in future studies of this molecule and its complexes. Full article