Search Results (146)

We hypothesized that compounds containing ether linkages within their backbone structures, when exposed to hydroxyl radicals (•OH), can generate ultra-weak photon emission (UPE) as a result of the formation of triplet excited carbonyl species (³R=O*). To evaluate this hypothesis, we investigated the UPE of four compounds, each at a final concentration of 185.2 µmol/L: EGTA (ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid), a potent chelator of divalent cations, and three crown ethers—12-crown-4, 15-crown-5, and 18-crown-6—containing two, four, five, and six ether bonds, respectively. •OH was generated using a modified Fenton reagent—92.6 µmol/L Fe²⁺ and 2.6 mmol/L H₂O₂. The highest UPE was recorded for the Fe²⁺–EGTA–H₂O₂ (2863 ± 158 RLU; relative light units), followed by 18-crown-6, 15-crown-5, and 12-crown-4 (1161 ± 78, 615± 86, and 579 ± 109 RLU, respectively; p < 0.05), corresponding to the number of ether groups present. Controls lacking either H₂O₂ or Fe²⁺ exhibited no significant light emission compared to the buffer medium. These findings support the hypothesis that ether bonds, when oxidatively attacked by •OH, undergo chemical transformations resulting in the formation of ³R=O* species, the decay of which is associated with UPE. In crown ethers exposed to Fe²⁺-H₂O₂, the intensity of UPE was correlated with the number of ether bonds in their structure. Full article

This review surveys recent advances and emerging prospects in phase-transfer catalysis (PTC) for fuel desulfurization. In response to increasingly stringent environmental regulations, the removal of sulfur from transportation fuels has become imperative for curbing SO_x emissions. Conventional hydrodesulfurization (HDS) operates under severe temperature–pressure conditions and displays limited efficacy toward sterically hindered thiophenic compounds, motivating the exploration of non-hydrogen routes such as oxidative desulfurization (ODS). Within ODS, PTC offers distinctive benefits by shuttling reactants across immiscible phases, thereby enhancing reaction rates and selectivity. In particular, PTC enables efficient migration of organosulfur substrates from the hydrocarbon matrix into an aqueous phase where they are oxidized and subsequently extracted. The review first summarizes the deployment of classic PTC systems—quaternary ammonium salts, crown ethers, and related agents—in ODS operations and then delineates the underlying phase-transfer mechanisms, encompassing reaction-controlled, thermally triggered, photo-responsive, and pH-sensitive cycles. Attention is next directed to a new generation of catalysts, including quaternary-ammonium polyoxometalates, imidazolium-substituted polyoxometalates, and ionic-liquid-based hybrids. Their tailored architectures, catalytic performance, and mechanistic attributes are analyzed comprehensively. By incorporating multifunctional supports or rational structural modifications, these systems deliver superior desulfurization efficiency, product selectivity, and recyclability. Despite such progress, commercial deployment is hindered by the following outstanding issues: long-term catalyst durability, continuous-flow reactor design, and full life-cycle cost optimization. Future research should, therefore, focus on elucidating structure–performance relationships, translating batch protocols into robust continuous processes, and performing rigorous environmental and techno-economic assessments to accelerate the industrial adoption of PTC-enabled desulfurization. Full article

The utilization of magnetic fields in agricultural contexts has been demonstrated to exert a beneficial effect on various aspects of crop development, including germination, growth, and yield. The present study investigates the impact of magnetic biostimulation on seeds of purple maize (Zea mays L.), variety INIA 601, cultivated in Cajamarca, Peru, with a particular focus on their physical characteristics, yield, bioactive compounds, and antioxidant activity. The results demonstrated that seeds treated with pulsed (8 mT at 30 Hz for 30 min) and static (50 mT for 30 min) magnetic fields exhibited significantly longer cobs (16.89 and 16.53 cm, respectively) compared with the untreated control (15.79 cm). Furthermore, the application of these magnetic fields resulted in enhanced antioxidant activity in the bract, although the untreated samples exhibited higher values (110.56 µg/mL) compared with the pulsed (91.82 µg/mL) and static (89.61 µg/mL) treatments. The geographical origin of the samples had a significant effect on the physical development and the amount of total phenols, especially the antioxidant activity in the coronet and bract. Furthermore, a total of fourteen phenols were identified in various parts of the purple maize, with procyanidin B2 found in high concentrations in the bract and crown. Conversely, epicatechin, kaempferol, vanillin, and resveratrol were found in lower concentrations. These findings underscore the phenolic diversity of INIA 601 purple maize and its potential application in the food and pharmaceutical industries, suggesting that magnetic biostimulation could be an effective tool to improve the nutritional and antioxidant properties of crops. Full article

In view of the difficulties encountered when tuning parameters and the lack of anti-interference capabilities exhibited by high-precision trajectory-tracking control of quadrotor UAVs in complex dynamic environments, this paper proposes a fusion control framework based on an improved crowned pig optimisation algorithm (ICPO) and preset performance anti-disturbance control (PPC-ADRC). Initially, this paper addresses the limited convergence efficiency of the traditional crowned pig algorithm (CPO) by introducing a dynamic time threshold mechanism and an adaptability-based directed elimination strategy to balance the algorithm’s global exploration and local development capabilities. This results in a significant improvement in the convergence speed and optimisation accuracy. Secondly, a hierarchical control architecture is designed, with the outer loop using a PPC-ADRC controller to dynamically constrain the tracking error boundary using an exponential performance funnel function and a combined state observer (ESO) to estimate the compound disturbance in real time. The inner-loop attitude control uses ADRC, and the 24-dimensional parameters of the ADRC (including the ESO bandwidth and non-linear feedback gain) are optimised autonomously using the ICPO to achieve efficient parameter tuning. The simulation experiments demonstrate that, in comparison with the original CPO, the ICPO attains an average fitness ranking that is superior in the CEC2014–2022 benchmark test, thereby substantiating its global optimisation capability. In the PPC-ADRC controller parameter optimisation, the preset performance of the ICPO-tuned PPC-ADRC controller (PPC-ADRC) is superior to that of the particle swarm optimisation (PSO), genetic algorithm (GA) and original CPO. The ICPO-based PPC-ADRC controller is shown to reduce the total error by more than 45.6% compared to the ordinary ADRC controller in the task of tracking a spiral trajectory, and it effectively reduces the overshoot. Its capacity to withstand complex wind disturbances is notably superior to that of the traditional PID and ADRC architectures. Stability analysis further proves that the system satisfies the Lyapunov convergence condition in a finite time. This research provides a theoretical foundation for the high-precision control of UAVs in complex dynamic environments. Full article

Crown ethers have gained importance in the field of medicine because of their resemblance to natural ionophores like valinomycin. With the goal of developing new pharmacologically important crown ethers, a novel series of crown ethers linked with Fusidic acid butyl ester 10a–d were synthesized and characterized by means of their ¹H NMR, ¹³C NMR DEPT-135, FT-IR, and mass spectrometry. In vitro antioxidant and α-glucosidase inhibition activities of all crown ethers along with the precursor Fusidic acid butyl ester were examined and compared to the standard butylated hydroxyanisole and acarbose, respectively. Compounds (FABE-16-crown-4) 10b and (FABE-19-crown-5) 10c showed high antioxidant potential with the IC₅₀ = 22.5 ± 0.2 μM and 32.1 ± 0.3 μM, respectively, when compared to the standard BHA (IC₅₀ = 44.2 ± 0.34 μM). To understand the binding mode of the compounds, molecular docking investigations were performed using human antioxidant protein, peroxiredoxin 5. Molecular docking studies revealed higher docking scores (−6.5 and −6.7 kcal/mol) for the highly active compounds 10c and 10b, respectively, than standard BHA (−5.3 kcal/mol). Synthesized crown ethers exhibited moderate α-glucosidase inhibition with (IC₅₀ = 23.5 ± 0.2 to 76.5 ± 0.1 μM) when compared to acarbose as standard (IC₅₀ = 5.2 ± 0.8 μM). The in silico ADMET predictions indicated that the prepared compounds obeyed (bRO5) and Veber’s rule for the acceptance as orally administered drugs and indicated that all the prepared crown ethers exhibited calculated values of drug likeness parameters in acceptable ranges that showed good potential of these molecules for further drug development investigations. Full article

Fusarium graminearum is a common plant pathogen among cereals worldwide. The application of chemical antifungal compounds is the most frequently used method in controlling F. graminearum. However, its excessive use and the genomic plasticity of the fungal genome lead to increased resistance levels to these chemical antifungal compounds. In this context, plant-derived compounds might play a role in protecting against Fusarium head blight (FHB) and crown rot (CR) as an alternative. In this study, we aimed to examine the antifungal effects of an essential oil obtained from Rosa damascena Mill. on the plant pathogen F. graminearum using molecular and analytical methods. The chemical composition of the essential oil was determined by GC-MS. The half effective concentration (EC₅₀) value of R. damascena essential oil (REO) for F. graminearum was determined as 604.25 µg mL⁻¹. Water-soluble tetrazolium 1 (WST-1) analyses revealed that REO caused cytotoxicity in F. graminearum. The potential oxidative stress and autophagic cell death capacity of REO towards F. graminearum was revealed via gene expression analysis and fluorescence microscopy. It was also revealed that, due to the plant-protective effect of REO, the disease severity of treated plants decreased by up to 27.78% in juvenile wheat seedlings infected by F. graminearum. Our data show that R. damascena essential oil might be used as an alternative natural ingredient in the field of plant protection. Full article

Herein, we present hybrid crown ether ligands with siloxane and ethylene oxide units and their coordination with the cations Li⁺, Na⁺, Mg²⁺ and Ca²⁺. The compounds prepared are (SiMe₂O)₂(C₂H₄O)₃ (1, TrEGDS = Triethylenglycoldisiloxane) and (SiMe₂O)₂(C₂H₄O)₄ (2, TeEGDS = Tetraethylenglycoldisiloxane)), as well as the metal complexes [Li(TrEGDS][GaI₄] (3), [Na(TeEGDS)][GaI₄] (4), [Mg(TrEGDS)][GaI₄]₂ (5) and [Ca(TeEGDS)][GaI₄]₂ (6). Single-crystal X-ray diffraction was used to study the prepared complexes and coordination modes in the solid state. Full article

Background/Objectives: Crown ethers have received increasing interest owing to their ability to form stable complexes with cations. This molecular feature has been successfully exploited in the development of biologically relevant ionophores. Methods: In order to obtain innovative crown ethers derivatives, a Morita–Baylis–Hillman adduct (MBHA) acetate (4) bearing a phenylacetylene moiety was dimerized via the click-chemistry CuAAC reaction with oligo(ethylene glycol) diazide derivatives to build-up a small series of dimeric MBHA derivatives (5a-d). These dimeric MBHA derivatives were reacted with n-butylamine to afford tunable macrocyclic crown ether-paracyclophane hybrid architectures (6a-d). Results: Compounds (E,Z)-6a, (E,E)-6a, 6b-d showed, in human breast cancer MDA-MB-231 and human melanoma A375 cells, IC₅₀ values comparable with those of reference anticancer agent Doxorubicin. Conclusions: This exploration approach provides original new macrocyclic architectures potentially useful as anticancer agents. Full article

Pineapple (Ananas comosus) is one of the most economically important fruit cultivars in South Africa. The fruit is locally consumed, processed into various industrial products or exported to foreign markets. Approximately 115,106 metric tons of pineapple fruit are harvested in South Africa. The pineapple value chain generates significant amounts of waste, in the form of pomace, peel, crown, stem, core and base. If not properly treated, pineapple waste (PAW) could have a profound detrimental impact on the environment. This calls for advanced technological platforms to transform PAW into useful bio-based products. A biorefinery is a potent strategy to convert PAW into multiple food and non-food products while effectively disposing of the waste. The objective of this review is to explore possible pathways for the valorization of PAW into energy and material products in a biorefinery. The paper looks at 10 products including biogas, biohythane, bioethanol, biobutanol, biohydrogen, pyrolytic products, single-cell proteins, animal feed, vermicompost and bioactive compounds. Several platforms (i.e., biochemical, chemical, physical and thermochemical) are available to convert PAW into valuable goods. Amongst them, the biochemical route appears to be the most favorable option for the valorization of PAW. Anaerobic digestion and fermentation are well-established biochemical technologies for PAW valorization. These methods are simple, low-cost, eco-friendly and sustainable. The focal point of emerging research is the enhanced efficacy of biorefinery platforms. The commercialization of PAW biorefining is a potential gamechanger that could revitalize the entire South African economy. Full article

Beneficial bacteria are recognised for their antimicrobial compounds, making them valuable for disease control in agriculture. Bacillus species stand out for their stability, versatility, and selectivity as biocontrol agents. This study aimed to identify potential antagonists within the rhizosphere microorganisms by isolating bacterial strains from grapevine roots and rhizosphere soil in Moroccan vineyards. The antimicrobial activities of these isolates against Allorhizobium vitis, the causative agent of grapevine crown gall, were evaluated in vitro using a disc diffusion assay, followed by in planta assessments under preventive and simulated inoculation conditions. Screening led to the isolation of 123 strains, with six showing strong antagonistic properties, achieving inhibition percentages up to 39.6%. 16S rRNA sequencing led to identifying five Bacillus species: B. amyloliquefaciens, B. velezensis, B. halotolerans, B. subtilis, and B. anthracis. These strains were further characterised by their biochemical traits and plant growth-promoting abilities. Compatibility assays identified optimal combinations for microbial consortia, demonstrating pathogen inhibition up to 37.4%. In planta bioassays confirmed the effectiveness of the isolates and consortia, reducing tumour size. These findings highlight the potential of these Bacillus strains as biocontrol agents and underscore the value of microbial consortia as a sustainable approach to managing grapevine crown gall. Full article

A new Na⁺ ionophore with two 12-crown-4 moieties on silicon atoms and hydrophobic hydrocarbon groups on silicon atoms has been synthesized. The silicon-bridged bis(12-crown-4)s were easily obtained in high yield by simply mixing dichlorodiorganosilane and 2-hydroxymethyl-12-crown-4 under room temperature and nitrogen atmosphere. Seven compounds with different hydrocarbon substituents were synthesized. To investigate their properties as ionophores, PVC membrane-type ion-selective electrodes incorporating them were prepared, and the ion selectivity coefficients were determined. The typical selectivity sequence is Na⁺ > K⁺ > Rb⁺ > Cs⁺ > NH₄⁺ > Li⁺ > Ca²⁺ > Mg²⁺ > H⁺. The magnitude of selectivity depends on the structures of hydrocarbon substituents on the silicon atoms. The compound with two 2-ethylhexyl groups has particularly good Na⁺ selectivity, and the performance of the electrode is equal to or better than that of an electrode using a commercially available Na⁺ ionophore, malonate-bridged bis(12-crown-4). The electrode also showed better-aging stability than that of another known Na⁺ ionophore, tetraethyl 4-tert-butylcalix[4]arene-O,O′,O″,O‴-tetraacetate, indicating high utility. Full article

Procyanidins are widely distributed in plant-derived foods, and consist of flavanol oligomers and polymers. Recently, the crown procyanidin sub-family, characterised by a unique macrocyclic structure, has been identified in grapes and wine. This study reports the development and validation of a rapid and quantitative analytical method measuring crown procyanidin concentration in red and white wines using ultra-high-performance liquid chromatography (UHPLC) coupled with a Q-TOF mass spectrometer. Validation followed international standards, demonstrating high sensitivity (LOQ = 0.033 mg/L), accuracy (recovery = 88.21% to 107.64%), repeatability (RSD = 1.99% to 11.03%), and intermediate reproducibility (RSD = 2.51% to 19.05%). Minimal matrix effects were observed, ensuring reliable and precise quantification across both wine types. The applicability of the method was confirmed through the successful analysis of wine samples, leading to the first quantification of crown procyanidins in white wine. Concentrations ranged from 0.81 mg/L to 15.88 mg/L in the different analysed wines. This validated method provides a valuable tool for the study of crown procyanidin profiles in various wine matrices and establishes a foundation for future research into the role of crown procyanidins in wines and other food and beverage matrices where these compounds may be present. Full article

Culinary rhubarb is grown for its large, thick leaf petioles. Red-stalked cultivars and selection are more attractive for the fresh market and processing industry. In vitro cultures are important for rapidly multiplying value genotypes and producing plants free of viruses. This study aimed to develop an in vitro propagation method for six rhubarb selections from the Raspberry (R1, R2, R3), Leader (L1, L2), and Karpow Lipskiego (KL) groups. In addition, the planting material of six rhubarb selections was subjected to phytochemical analysis using the HPLC method to assess the content of bioactive compounds. The cultures were initiated from underground buds on the crowns. The initial growth was obtained for 45 to 75% of initial explants because of bacterial contamination and low bud activity of some genotypes. The type and concentration of cytokinin and its interaction with gibberellin acid (GA₃) were shown to have a significant effect on the cyclic multiplication and commercially interesting rate of all rhubarb genotypes. A high in vitro rooting frequency, 93.7 to 95.8% for rhubarb Raspberry, 94.3 to 100% for rhubarb Leader, and 96.7% KP selections were obtained after two-cycle rooting on a medium containing IBA and NAA. The polyphenolic compounds, such as cyanidin-3-O-rutinoside, rhaponticin, resveratrol, caffeic acid, p-coumaric acid, cinnamic acid, syringic acid, and ferulic acid were detected in selected rhubarb genotypes. The highest content of anthocyanins (2.9 mg·1 g⁻¹ DM) and rhaponticin (107.8 µg·1 g⁻¹ DM) was found in Raspberry selections. On the other hand, Leader selections were characterized by the highest content of resveratrol (0.25 µg·1 g⁻¹ DM) and phenolic acids (1.3 µg·1 g⁻¹ DM). The less attractive for functional food production seems to be KL selection. Full article

Danielle Abrams’s performance art critically engages with late twentieth-century debates on race, queerness, and identity, positioning her as a vital figure in challenging monolithic and heteronormative structures of identity. Her early work Quadroon (1998), a live performance and four-channel video installation blending music, costume, gesture, and speech, compounds impassioned debates within the art world and beyond around the impact of multiculturalism on identity-based art, the invisibility of Jews of color and other marginalized members of the Jewish community, and the state of Black/Jewish relations in the United States following the Crown Heights riots of 1991. Abrams’s pieces frequently negotiate the tensions and intersections between her Black and Jewish familial heritage and her lesbian identity through the embodiment of semi-fictional personae grounded in family lore, self-perceptions, and cultural stereotypes. This paper explores how Abrams destabilizes the readability of “authentic” identities on the surface of the body in Quadroon via her adoption of personifications of her Black grandmother, her Jewish great grandmother, her identification as a butch lesbian, and her (unsuccessful) teenage attempt at passing for Greek. Pairing video recordings of each character with interludes from an unpublished performance script, I consider the anxieties of passing expressed in the personas of Dew Drop and Janie Bell, and through the lens of Abrams’s diaries, pose Butch in the Kitchen’s potential as an indefinite body to queer socially imposed constructions of monolithic and essentialist identity. Full article

Cisplatin (DDP), a platinum-chelated compound renowned for its antitumor activity, is often utilized in cancer therapy. However, its real-world clinical efficacy is compromised by poor solubility and low stability, which impedes wider clinical application. Our study aimed to address these limitations of DDP through host–guest supramolecular chemistry approaches. We explored the potential of 18-crown-6 as the host molecule to solubilize and stabilize DDP, the guest molecule. Utilizing techniques such as UV–visible spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and molecular docking, we conducted a comprehensive analysis on the physical state and inclusion mode of the DDP@18-crown-6 complex. Phase solubility studies and Job’s plot confirmed that the DDP@18-crown-6 complex significantly enhanced the aqueous solubility of DDP, with an optimal 1:1 binding ratio. Stability analyses revealed that this complex markedly improved the stability of DDP in pure water. Meanwhile, the stabilization effects of DDP@18-crown-6 were remarkably elevated when combined with 0.9% sodium chloride. In vitro antitumor assays in A549 cell lines demonstrated that the DDP@18-crown-6 complex outperformed raw DDP in cytotoxicity, showing a significantly lower IC₅₀ value. This research offered a promising strategy for DDP solubilization and stabilization, facilitating its anticancer therapeutic efficacy. Full article