Aqueous Ethanol Solution Research Articles

Rapid Synthesis of Noble Metal Colloids by Plasma-Liquid Interactions.

The interactions between plasma and liquids cause complex physical and chemical reactions at the gas-liquid contact surface, producing numerous chemically active particles that can rapidly reduce noble metal ions. This study uses atmospheric-pressure surface dielectric barrier discharge (DBD) plasma to treat ethanol aqueous solutions containing noble metal precursors, and stable gold, platinum, and palladium colloids are obtained within a few minutes. To evaluate the mechanism of the reduction of noble metal precursors by atmospheric-pressure surface DBD plasma, the corresponding metal colloids are prepared first by activating an ethanol aqueous solution with plasma and then adding noble metal precursors. It is found that the long-lived active species hydrogen peroxide (H2O2) plays a dominant role in the synthesis process, which has distinct effects on different metal ions. When HAuCl4 and H2PdCl4 are used as precursors, H2O2 acts as a reducing agent, and AuCl4- and PdCl42- ions can be reduced to metallic Au and Pd. However, when AgNO3 is the precursor, H2O2 acts as an oxidising agent, and Ag+ ions cannot be reduced to obtain metal colloids because metallic Ag can be dissolved in H2O2 under acidic conditions. A similar phenomenon was also observed for the preparation of Pd colloid-PA with a plasma-activated ethanol aqueous solution using Pd(NO3)2 as a Pd precursor.

The Preferential Solvation of Methyl Red in Various Binary Aqueous Solutions: Solvatochromism, Preferential Solvation Parameters, Microheterogeneity of Solvents and Polarity Scale.

The solvatochromic characteristics of methyl red were examined in several aqueous solutions from pure water, with methanol, ethanol, propanol, acetonitrile, and dioxane. In order to explain the preferred solvation of the probe azo dye in the binary mixed solvents, the solvent exchange model of Bosch and Roses was used to evaluate the association between the empirical solvent polarity scale (ET) values of MR and solvent composition. Non-linear solvatochromism of methyl red was noted in all aqueous mixtures containing methanol, ethanol, propanol, acetonitrile, and dioxane. In addition to calculating the local mole fraction of each solvent composition in the cybotactic area of the probe, the impact of the solvating shell composition on the preferential solvation of the solute dye was examined in terms of both solvent-solvent and solute-solvent interactions. The local mole fraction of each solvent composition in the cybotactic region of the probe was also calculated. The results indicated that the MR solvation shell was thoroughly saturated with the solvent complex S12 in the following order: dioxane > ethanol > methanol > acetonitrile > propanol. Data from the binary systems were analyzed with KAT parameters using a multi-model; in aqueous methanol and ethanol solutions, the hydrogen acidity was more responsible for the spectral shift, whereas in aqueous acetonitrile and dioxane solutions, the basicity has a greater influence.

Experimental and theoretical research on oscillation behavior of droplets on horizontally oscillating substrates

The oscillation behavior of a droplet on a horizontally oscillating flat substrate was studied. We derived a formula to relate the resonance frequency and damping constant of the horizontal oscillation of the droplet to the physical properties of the liquid materials, which were examined experimentally. The resonance frequency and damping constant were expressed as functions of surface tension, droplet radius, contact angle, density, and viscosity. Furthermore, we observed the non-equilibrium phenomenon of the droplet through the adsorption of molecules from the surrounding gas phase onto the droplet surface. We demonstrated the time evolution of the surface tension of an ethanol aqueous solution, and the decrease in surface tension due to the evaporation of ethanol was detected using the newly developed system.

Phytochemical, Technological, and Pharmacological Study on the Galenic Dry Extracts Prepared from German Chamomile (Matricaria chamomilla L.) Flowers

Galenic preparations of German chamomile are used to treat mild skin diseases, inflammation, and spasms, and they have also been reported to have anxiolytic and sedative effects. The medicinal use of chamomile is well known in ethnomedicine. After obtaining its galenic preparations, there is lots of waste left, so it is expedient to develop waste-free technologies. The aims of this study were to gain knowledge of the ethnomedical status of chamomile in the past and present, develop methods for preparing essential oils and dry extracts from German chamomile flowers using complex processing, reveal the phytochemical composition of such extracts, and verify the analgesic and soporific activity of the extracts. Two methods for the complex processing of German chamomile flowers were developed, which allowed us to obtain the essential oil and dry extracts of the tincture and aqueous extracts as byproducts. A total of 22 phenolic compounds (7 hydroxycinnamic acids, 13 flavonoids, and 2 phenolic acids) were found in the dry extracts by using UPLC-MS/MS. In total, nine main terpenoids were identified in the chamomile oil, which is of the bisabolol chemotype. During the production of chamomile tincture, a raw material–extractant ratio of 1:14–1:16 and triple extraction are recommended for its highest yield. In in vivo studies with mice and rats, the extracts showed analgesic activity and improvements in sleep. The highest sedative and analgesic effects in rodents were found with the dry extract prepared by using a 70% aqueous ethanol solution for extraction at a dose of 50 mg/kg. The developed methods for the complex processing of German chamomile flowers are advisable for implementation into the pharmaceutical industry to reduce the volume of waste during the production of its essential oil and tincture, and to obtain new products.

The mineral phase evolution characteristics and hydration activity enhancement mechanism of steel slag under NaOH alkaline excitation

During the slow cooling process of steel slag, crystals of the inert ore phase (C2F) and active ore phase (C2S, C3S) grow dependently, and the irregular interlacement and coating between ore phases strongly affect the hydration activity of the active ore phase in steel slag. Therefore, in this article, a typical alkaline activator, NaOH, was selected, the solvent type and concentration were optimized, and the etching behavior and mechanism of action of the NaOH alkaline activator on the surface of steel slag particles were clarified by analyzing the mineral phase composition, microstructure, particle size distribution, and pore structure evolution characteristics under alkaline excitation. In addition, the water hydration products, microstructure, exothermic hydration and thermogravimetric data before and after the excitation of steel slag were characterized, revealing the mechanism of enhancing the hydration activity of steel slag under alkaline NaOH stimulation. The results showed that both NaOH aqueous solution and ethanol solution could effectively increase the mass fraction of active mineral phases in steel slag; among them, the 0.08 mol/L NaOH ethanol solution had the best chemical activation effect on the steel slag. Compared with that of the raw steel slag, the total mass fraction of the active mineral phases (C2S and C3S) increased from 37.3 wt% to 45.6 wt%, and the mass fraction of the inert mineral phase C2F decreased from 38.3 wt% to 19.1 wt%. The consumption of active mineral phases in steel slag is reduced by the water in the activator. The alkaline activator erodes the dense inert mineral phase C2F on the surface of the steel slag particles, resulting in etching pits that expose the active silicate mineral phase and provide additional hydration sites. The cumulative heat release from the steel slag after alkaline excitation was 116.27 J/g at 72 h, which was 66.88 J/g higher than that of the raw steel slag. These conditions significantly improved the early hydration performance of the steel slag and promoted the formation of amorphous cementitious products (CH, C-S-H and AFt) in the steel slag system, which subsequently filled the capillary pores of the steel slag and formed a denser microstructure.

Quantification and discovery of quality markers from Toddalia asiatica by UHPLC-MS/MS coupled with chemometrics.

Toddalia asiatica (TA) is a classical traditional Chinese medicine used to treat rheumatoid arthritis and contusions. However, research regarding TA quality control is currently limited. We aimed to establish a strategy for identifying quality markers that can be used for the evaluation of the quality of TA. A rapid and efficient ultra-high-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (UHPLC-MS/MS) method was developed for the quantitative determination of 19 compounds in TA from different regions. Then, the extraction process of TA was successively optimized by single-factor optimization and response surface methodology. Moreover, chemometrics was employed to confirm the correlation between quality and target compounds. Utilizing the UHPLC-MS/MS method, separation of the 19 bioactive compounds was achieved within 14 min. The method was validated in terms of linearity (r2 > 0.9982), precision (0.08%-3.70%), repeatability (0.50%-2.54%), stability (2.26%-5.46%), and recovery (95.8%-113%). The optimal extraction process (extraction solvent, 65% ethanol aqueous solution; solid-liquid ratio, 1:20; extraction time, 25 min) was determined with the total content of 19 bioactive compounds as indicator. Significant disparities were observed in the contents of target compounds across different batches of TA. Besides, all samples could be categorized into two distinct groups, and magnoflorine, (-)-lyoniresinol, nitidine chloride, norbraylin, skimmianine, and decarine were identified as quality markers. In the present study, we developed a strategy to improve the quality control of TA. In consideration of the pharmacodynamic activity and statistical differences, six compounds are proposed as quality markers for TA.

Synthesis and characterization of high-flux ZIF-90/poly-dimethyldiethoxysilane (PDMDES) mixed matrix membrane for enhanced pervaporation recovery of alcohols

In the present research, micron-sized zeolitic imidazolate framework-90 (ZIF-90) particles were synthesized utilizing an adapted synthesis route and subsequently incorporated into the poly-dimethyldiethoxysilane (PDMDES) polymer to fabricate ZIF-90/PDMDES mixed matrix membrane (MMM) with an objective to achieve enhanced pervaporation performance for the efficient separation of alcohols from aqueous solutions. Comprehensive characterization techniques were employed to investigate the properties of the ZIF-90 particles and the newly fabricated ZIF-90/PDMDES MMMs. Encouraging findings revealed that the incorporation of microporous ZIF-90 particles led to notable enhancements in hydrophobicity, alcohol affinity, and thermal stability of the MMMs. Notably, a distinctive cross-sectional morphology of the ZIF-90/PDMDES MMMs were observed at lower ZIF-90 loadings, a phenomenon attributed to the disparity between the ZIF-90 particle size and the inherent thickness of the PDMDES layer. Systematic evaluations were conducted to ascertain the influence of ZIF-90 loadings, feed concentration, and operational temperature on the pervaporation performance of ZIF-90/PDMDES MMMs. Accordingly, the optimal separation performance was obtained at the ZIF-90 loading of 5 wt% when separating ethanol from 5 wt% ethanol aqueous solution at 40 °C, yielding an impressive total flux of 6.51 kg∙m−2 h−1, a separation factor of 7.29, a PSI of 40.95 kg∙m−2 h−1, and an ethanol permeability of 7.45 × 104 Barrer.

Adequate assessment of linear function of calibration according to GOST R ISO 11095-2007 for ethanol mass concentration measurement

To assess the adequacy of linear function of calibration according to GOST R ISO 11095-2007 for ethanol mass concentration measurement using internal reference materials (RMs). An experiment on calibration in accordance with the GOST R ISO 11095-2007 National standard of the RF was carried out using internal RMs, namely aqueous solutions of ethanol at different concentrations. Measurements were performed for two subbands of ethanol concentrations at RMs: 0.15-1.05 and 1.0-7.0 mg/ml - according to the certified methodology. The graphs of the calibration's functions based on experimental data are consistent with the assumption of the calibration function's linearity, as well as the assumption of the standard deviation's constance of residues is equitable for two subbands of RMs. Proven linear models in the calibration experiment may be recommended for use in the ethanol mass concentration measurement.

STABILITY OF COBALT AND NICKEL COMPLEXES OF SUCCINIC AND MALEIC IONS STUDIED BY POTENTIOMETRIC TITRATION, UV-VIS SPECTROPHOTOMETRY AND QUANTUM CHEMICAL CALCULATIONS

In this study, composition and stability of coordination compounds of nickel (II) and cobalt (II) ions with succinate anion (L2-) and maleic anion (Y2-) in aqueous ethanol solutions with the molar concentration of ethanol ranging from 0.0 – 0.3 were studied by UV – Vis spectrophotometry at ionic strength of 0.1 maintained with sodium perchlorate. The result showed that, the formation of mono-ligand complexes of Ni2+ and Co2+ ions with succinate and maleic anions become stronger when the volume of ethanol rises. This may be due mainly to a change in the solvate state of the ligand with increasing ethanol concentration in the solvent. In all surveyed solvents, Co2+ forms less stable complexes than Ni2+ ion corresponding to the Irving-Williams series established for aqueous solutions. Obtained results were compared with literature data for akin compounds. The effect of solvent composition change on the geometry, charge, total electron and free Gibbs energies was studied using the DFT and MP2 levels of theory by using the Polarizable Continuum Model (PCM). The results obtained in this article by UV – Vis spectrophotometry and theoretical calculations were analyzed together with the potentiometric titration results obtained by us earlier for these complexes. The results of theoretical calculations are in good agreement with experimental data.

Activated carbon fibers functionalized with superhydrophilic coated pDA/TiO2/SiO2 with photoluminescent self-cleaning properties for efficient oil-water separation

The adhesion of high-viscosity oil contamination poses limitations on three-dimensional (3D) materials' practical use in treating oilfield-produced water (OPW). In this study, we developed a hybrid pDA/TiO2/SiO2 coating (PTS) on the surface of hydrophilic activated carbon (ACF1) through a combination of dopamine (DA) polymerization, ethyl orthosilicate (TEOS) hydrolysis, and the condensation of TiO2 nanoparticles (NPs) with SiO2 NPs. This coating was designed for gravity-based oil-water separation. The inherent porosity and generous pore size of ACF1-PTS conferred it an ultra-high permeation flux (pure water flux of 3.72 × 105 L∙m−2∙h−1), allowing it to effectively separate simulated oil-water mixtures and oil-water emulsions while maintaining exceptional permeation flux and oil rejection efficiency. When compared to cleaning methods involving ethanol aqueous solutions and NaClO, ultraviolet (UV) illumination cleaning proved superior, enabling oil-contaminated ACF1-PTS to exhibit remarkable flux recovery efficiency and oil-removal capabilities during cyclic separation of actual OPW. Furthermore, the ACF1-PTS material demonstrated impressive stability and durability when exposed to acidic environments (acid, alkali, and salt), robust hydraulic washout conditions, and 25-cycle tests. This study offers valuable insights and research avenues for the development of highly efficient and environmentally friendly 3D oil-water separation materials for the actual treatment of OPW.

Effect of Solvent on Ionomer Adsorption Behavior of Polymer Electrolyte Membrane Fuel Cell Catalyst

Polymer electrolyte membrane fuel cell (PEMFC) is a promising power source with zero local carbon emissions that may aid in realizing the development of low-carbon societies. Catalyst layers (CL) composed of catalyst composites and an ionomer are key components in PEMFC. To control the structure of the CL, especially for the localization of the ionomer, understand the adsorption behavior on carbon surface is important. The quantitative analysis of ionomer adsorption isotherm is a powerful tool for analyzing the adsorption behavior, however, existing experiments have been carried out in water, and the effects of alcohol are yet to be considered. Because the mixtures of water/alcohol are used in the actual fabrication of PEMFC, the adsorption isotherm using the binary mixtures of water/alcohol as the solvents could provide practical information to optimize the PEMFC performance.Principal project of this study is to investigate and evaluate the effects of the alcohol contents on the interaction between the ionomer (Nafion) and the surface of the carbon support. The control of the interaction between ionomers and catalyst composites is as well as crucial in controlling the PEMFC performance. As the catalyst composites, commercial Vulcan/Pt (CB/Pt) and Pt-loaded polybenzimidazole (PBI) polymer-wrapped Vulcan (CB/PBI/Pt) catalysts were compared. For the detailed Nafion adsorption experiment, using synthesized CB/PBI/Pt and commercial CB/Pt disperse in aqueous ethanol solutions (87 or 20 wt%) with different amounts of Nafion (i.e., carbon-to-ionomer weight ratio, I/C=0.1~1.4). Then the dispersions were filtered with a syringe filter, and the filtrates were measured with 19F-NMR to calculate the amount of adsorption. For 19F-NMR, filtrates were added to trifluoroacetic acid and heavy water used as internal standard and deuterium solvent, respectively. The amount of Nafion was calculated based on the integral ratio of the largest peaks of Nafion ranging from −115 to −130 ppm in reference to the trifluoroacetic acid peak at −75.5 ppm. To prepare the adsorption isotherm, the adsorption amount (Γ [mg·mg−1]) of Nafion was plotted as a function of the equilibrium concentration (C e). The maximum adsorption amount (Γ max [mg·mg−1])) and Langmuir constant (K L) were determined based on the Langmuir equation. This paper will also discuss the difference in CL structure and cell performance at I/C=0.72 which formulation in low (water-) and high ratio alcohol (alcohol-rich) in ink solvent.PBI-coated CB (CB/PBI) was prepared according to our previous reports1, and the adsorption isotherms were measured in water- and alcohol-rich solvents (Figure.1), in which the BET values of 88 and 119 m2·g-1 for CB/PBI and CB/PBI/Pt, respectively, were used for the calculation of Γ’ (mg·m−2) in place of Γ (mg·mg−1). For the first layer adsorption, K L was calculated as 82 and 55 in the water- and alcohol-rich solvents, respectively. Comparing these values with those of CB, clear increase of the K L in the alcohol-rich solvent from 32 (CB) to 55 (CB/PBI) was obtained, whereas the K L values in the water-rich solvent were almost comparable between CB (89) and CB/PBI (82). In addition, the Γ max of the first layer in the alcohol-rich solvents increased from 0.024 mg mg‒1 (CB) to 0.034 mg mg‒1 (CB/PBI), while that in water-rich solvents were comparable between CB (0.043 mg mg‒1) and CB/PBI (0.043 mg mg‒1). Both results clearly indicate the stronger interaction between PBI and Nafion compared to the interaction between CB and Nafion in alcohol-rich solvents, while strong interaction in water-rich solvents was still maintained. A similar trend was also observed for Pt-loaded CB/PBI (CB/PBI/Pt), namely, the K L (43) and Γ’max (0.218 mg·m−2) were larger than those of CB/Pt (K L = 25 and Γ’max = 0.179) in the alcohol-rich solvent, while in water-rich solvent, K L (44) and Γ’max (0.277 mg·m−2) of CB/PBI/Pt were very high similar to CB/Pt (K L = 29 and Γ’max = 0.188 mg·m−2). On the other hand, when we compare Γ’max values of CB/PBI and CB/PBI/Pt, the decrease of the values after Pt loading in the water-rich and alcohol-rich solvents were observed, suggesting the Nafion adsorption onto Pt surface is inferior for PBI systems regardless of alcohol content.Furthermore, the performances of different catalysts were evaluated and discussed to understand the effect of alcohol content on Nafion adsorption and CL structure. Figure. 2 represents a performance curve that maximum power density of MEA having CB/Pt was 580 and 750W cm-2, while that of CB/PBI/Pt was 720 and 810 W cm-2, in alcohol and water-rich solvents, respectively. The high current density range (1.2~2A cm-2) also showed higher potential in water-rich conditions that related to O2 diffusion in CL.Reference 1. S. M. Jayawickrama,T. Fujigaya.et al. Electrochim. Acta. 312, 20 (2019). Figure 1

Wettability of Quartz by Ethanol, Rhamnolipid and Triton X-165 Aqueous Solutions with Regard to Its Surface Tension

The wettability of quartz by different liquids and solutions plays a very important role in practical applications. Hence, the wetting behaviour of ethanol (ET), rhamnolipid (RL) and Triton X-165 (TX165) aqueous solutions with regard to the quartz surface tension was investigated. The investigations were based on the contact angle measurements of water (W), formamide (F) and diiodomethane (D) as well as ET, RL and TX165 solutions on the quartz surface. The obtained results of the contact angle for W, F and D were used for the determination of quartz surface tension as well as its components and parameters using different approaches, whereas the results obtained for the aqueous solution of ET, RL and TX165 were considered with regard to their adsorption at the quartz–air, quartz–solution and solution–air interfaces as well as the solution interactions across the quartz–solution interface. The considerations of the relations between the contact angle and adsorption of solution components at different interfaces were based on the components and parameters of the quartz surface tension. They allow us to, among other things, establish the mechanism of the adsorption of individual components of the solution at the interfaces and standard Gibbs surface free energy of this adsorption.

A COMPREHENSIVE REVIEW ON CHALCONE ANALOGUES-VERSATILE SCAFFOLD WITH MEDICINAL AND BIOLOGICAL POTENTIAL

This review’s main focus is on the most recent synthesis of chalcones with N, O, or S heterocycles, highlighting their biological potential. Chalcone derivatives are considered in beneficial species because they possess a keto-ethylenic moiety, CO−CH=CH−. Due to the existence of a reactive α, β-unsaturated carbonyl group, the synthesis of chalcone derivatives, which have been physiologically explored for use against specific disease targets, has been made possible by recent advances in heterocyclic chemistry. The need for novel drugs that are effective against multidrug-resistant pathogens has been driven by the growth in antibiotic resistance brought on by a variety of reasons. Chalcones are phenolic compounds that fall within the flavonoids category. They are a part of a large category of naturally occurring bioactive substances. During this review we have gone through a number of studies where chalcones were created via Claisen Schmidt condensation of suitable acetophenone with suitable aromatic aldehydes in the presence of an aqueous solution of potassium hydroxide and ethanol at room temperature in an effort to create antibacterial agents. The review content have been obtained through web browsing on various scientific databases and search engines like Science Direct, Pub Med, Research Gate, Google Scholar, etc. The synthesis of diverse chalcone derivatives was motivated by the potential activity of naturally occurring chalcones as anticancer, anti-inflammatory, antibacterial, antioxidant, and antiparasitic characteristics, as well as by their unique chemical structural structure. Flavonoids and isoflavonoids, which are frequent chemical building blocks found in a variety of naturally derived compounds, are enhanced by chalcone. This review may prove to be helpful for the creation and design of new powerful therapeutic medications.

Extraction of Bioactive Compounds from Spent Coffee Grounds Using Ethanol and Acetone Aqueous Solutions.

Given global coffee consumption, substantial quantities of spent coffee grounds (SCGs) are generated annually as a by-product of brewing coffee. SCG, although rich in bioactive compounds, is nowadays disposed of. The objective of this study is to compare, for the first time and from the same SCG, the efficiency of ethanol-water mixtures and acetone-water mixtures for the recovery of total polyphenols, chlorogenic acid, and caffeine. Acetone at 20% (m/m) was the most convenient solvent to extract all three bioactive compounds simultaneously, yielding 4.37 mg of GAE/g SCG for total polyphenols, chlorogenic acid (0.832 mg 5-CQA/g SCG), and caffeine (1.47 mg/g SCG). Additionally, this study aims to address some challenges associated with the industrial-scale utilization of SCG as a raw material, encompassing factors such as pre-treatment conditions (natural drying and oven drying), storage duration, and the kinetics of the extraction process. No significant difference was observed between the natural drying and oven drying of SCG. In terms of storage duration, it is advisable to process the SCG within less than 3-4 months of storage time. A significant decline of 82% and 70% in chlorogenic acid (5-CQA) and caffeine contents, respectively, was observed after eight months of storage. Furthermore, the kinetic study for the recovery of total polyphenols revealed that the optimal extraction times were 10 min for acetone at 20% and 40 min for water, with a yield increase of 28% and 34%, respectively. What is remarkable from the present study is the approach considered, using the simplest operating conditions (minimal time and solvent-to-solid ratio, and ambient temperature); hence, at an industrial scale, energy and resource consumption and equipment dimensions can be together reduced, leading to a more industrially sustainable extraction process.

Durable magnetite-chitosan core–shell nanoparticles as reusable green nanocatalyst for the benign one-pot three-component synthesis of spirooxindoles and spirochromenes at ambient temperature under both solvent-free and ultrasonic conditions in aqueous ethanol solution

Durable magnetite-chitosan core–shell nanoparticles as reusable green nanocatalyst for the benign one-pot three-component synthesis of spirooxindoles and spirochromenes at ambient temperature under both solvent-free and ultrasonic conditions in aqueous ethanol solution

Flower-like vaterite produced by nanobubble-containing ethanol and water mixed solution for Cd (II) removal

CaCO3 crystals ranging from 3 to 15 μm in size have sparked significant scientific attention in many areas, such as materials, chemicals, medicine, and the environment. This study proposed a novel method for synthesizing flower-like vaterite calcium carbonate using nanobubble-containing ethanol and water mixed solution as the solvent based on the double decomposition method. The formation mechanism of vaterite with different shapes in ethanol aqueous solution containing nanobubbles was then discussed. Besides, the synthesized vaterite was used to remove cadmium based on chemisorption. Simultaneously, nanobubbles were used to improve the removal speed of Cd(II), providing a very interesting and promising field for studying heavy metal and pollutant adsorption in the liquid phase. The synthesized vaterite has a significant practical interest in the integrated treatment of wastewater contaminated by heavy metals with the facile and green synthesis procedure and effective Cd (II) removal.

A DFT-Based Mechanism Analysis of the Cyclodextrin Inclusion on the Radical Scavenging Activity of Apigenin.

Natural flavonoids are renowned for their exceptional antioxidant properties, but their limited water solubility hampers their bioavailability. One approach to enhancing their water solubility and antioxidant activity involves the use of cyclodextrin (CD) inclusion. This study investigated the impact of CD inclusion on the three primary radical scavenging mechanisms associated with flavonoid antioxidant activity, utilizing apigenin as a representative flavonoid and employing density functional theory (DFT) calculations. Initially, the optimized geometries of CD-apigenin inclusion complexes were analyzed, revealing the formation of hydrogen bonds between CD and apigenin. In less polar environments, the inclusion complex strengthened the bond dissociation enthalpies of hydroxyl groups, thereby reducing antioxidant activity. Conversely, in polar environments, the inclusion complex had the opposite effect by lowering proton affinity. These findings align with experimental results demonstrating that CD inclusion complexation enhances flavonoid antioxidant activity in aqueous ethanol solutions.

Au coated etched FBG SPR sensor for the detection of ethanol in aqueous solution

Over the past few years, there has been a growing need for reliable ethanol sensors in the pharmaceutical and food industries. These industries require constant monitoring to ensure that the acceptable ethanol levels are maintained. This study reports a new fiber optic sensor that uses etched single mode fiber Bragg grating (FBG) coated with the thin layer of 45 nm gold to produce Surface Plasmon Resonance (SPR). A thin layer of 45 nm gold improves the sensitivity of sensor by improving the evanescent wave around the fiber, resulting in better interaction with the analyte. The sensing performance of developed structure was examined by analyzing the change in wavelength shift observed by varying ethanol concentration in aqueous solution from 0 to 100 %. The performance of developed sensor in terms of sensitivity is 20 pm/RIU. Which is expected to play an important role in food and pharmaceutical industries to protect human health from detrimental affects due to high concentration of ethanol.

A magnetic molecularly imprinted polymer based on an eco-friendly deep eutectic solvent for the selective recognition of dichlorodiphenyl trichloroethane and its degradation products in fruits and vegetables

A new magnetic molecularly imprinted polymer was successfully synthesized using a ternary deep eutectic solvent derived from caffeic acid-choline chloride-formic acid as a functional monomer, thymol-menthol deep eutectic solvent as a template, ethylene glycol dimethacrylate as a cross-linker, potassium peroxodisulfate as an initiator, and aqueous ethanol solution (90% (v/v)) as a porogen. The synthesized material was characterized and applied for magnetic solid-phase extraction of dichlorodiphenyl trichloroethane and its degradation products. Optimization of the extraction condition was carried out using the central composite design and response surface methodology. The good analytical performance of magnetic solid phase extraction/gas chromatography‒mass spectrometry using the proposed adsorbent shows a wide linear range of 0.07–500 ng g−1 with R2 greater than 0.992. Low detection limits and quantitation limits were observed in the ranges of 0.01–2.00 ng g−1 and 0.07–2.50 ng g−1, respectively. The precisions shown in terms of relative standard deviations were lower than 7.0% for intraday (n=5) and 8.6% for interday (n=5 × 3) experiments. The proposed method was applied for preconcentration and determination of dichlorodiphenyl trichloroethane and its degradation products in fruit and vegetable samples. The satisfactory recoveries of the real samples at three spiked concentrations were obtained in the range of 79.1%–110.9% with RSDs lower than 7.5%. The findings highlight the importance of developing efficient sorbents for the enrichment of persistent organic pollutants in food matrices.

Structure and properties of some S-containing azo-derivatives of 5-pyrazolone and their Cu(II), Co(II), and Ni(II) metal complexes

Four S-containing azo-compounds based on 1-phenyl-3-methyl-4-azopyrazole-5-one and 10 novel metal complexes of Cu(II), Co(II), and Ni(II) were isolated and identified by X-ray single crystal analysis, FTIR, 1H NMR, and UV–Vis spectroscopy. The hydrazo-forms of the organic species in a solid state and solutions were proven. Studies of proteolytic equilibria, as well as complex formation in solutions, allowed the calculation of acidity and formation constants of the complexes in ethanol aqueous solutions. The types of coordination of organic species were determined by spectroscopic analysis together with X-ray analysis of a model complex. The sulfonamide group seems not to be involved in coordination. The toxicity of the compounds was determined based on the nature of the diazo-component and increased by replacing a benzene ring with a naphthol fragment. Computer screening revealed that the studied compounds exhibited the highest likelihood of enhancing HMGSC2 expression and displayed potential as antipyretics and anti-tuberculosis agents. Additionally, their solubilities in n-hexane, 1-octanol, and phosphate buffer at pH 7.4 were assessed. These solvents serve as models of physiological fluids and possess lipophilic properties that aid in membrane penetration. Subsequently, the thermodynamic constants were calculated.