Acid Dimer Research Articles

Removal of per- and polyfluoroalkyl substances by activated hydrochar derived from food waste: Sorption performance and desorption hysteresis

Carbonaceous materials, derived from waste biomass, have proven to be a viable and appealing alternative for removing emerging micro-pollutants, such as per- and polyfluoroalkyl substances (PFAS). To assess the feasibility and efficacy of using material derived from food waste to alleviate PFAS pollution, this study prepared activated hydrochar (AHC) for sorbing ten PFAS, including five perfluoroalkyl carboxylic acids (PFCA; C4–C8), three perfluoroalkyl sulfonic acids (PFSA; C4, C6, C8), and two emerging PFAS, namely hexafluoropropylene oxide dimer acid (commercial name GenX, an alternative to perfluorooctanoic acid (PFOA)) and 6:2 fluorotelomer sulfonic acid (6:2 FTS). The results demonstrated that AHC possessed a relatively high specific surface area (207 m2/g) and hydrophobic surface properties. At environmentally relevant concentrations (40 μg/L), the sorption partition coefficients (log Kd) of PFAS on AHC ranged from 2.33 to 6.49 L/kg. Notably, GenX exhibited a lower log Kd value (2.33 L/kg) than PFOA (3.88 L/kg). The AHC showed favorable sorption performance for all tested PFAS, with log Kd values surpassing other reported sorbents (e.g., 0.83 for GenX on pyrochar, and 2.83 for PFOA on commercial biochar). Additionally, desorption hysteresis was observed for all PFAS, except for PFOA, and was particularly pronounced in PFBA, GenX, and 6:2 FTS at high initial concentrations, with Hysteresis Index (HI) values varying from 0.31 to 1.45, 0.68 to 1.88, and 0.51 to 1.85, respectively. Given its robust sorption capacity and desorption hysteresis toward PFAS, AHC is expected to be a favorable candidate for remediating PFAS-contaminated water. This study underscores, for the first time, the potential of food waste-derived hydrochar as an efficient sorbent for alleviating PFAS contamination, and further study is needed to investigate the sorption and desorption behaviors of PFAS on AHC at various environmental conditions.

Dimer acid used as CO2‐responsive surfactant for reducing viscosity of heavy crude oil

AbstractThe efficacy of CO2‐switchable surfactants in reducing viscosity of heavy crude oil has received widespread attention due to its switchable surface activity for constructing reversible emulsion. However, the intricate synthesis processes of these surfactants pose a significant challenge in their practical application. The present investigation involved the preparation of surfactants that are responsive to CO2, specifically dimer acid (DA)/tetramethylpropylenediamine (TMPDA), through a facile mixing approach. These surfactants were subsequently employed to mitigate the high viscosity of heavy crude oil. The study employed a surface tension meter to examine the surface behavior of DA/TMPDA, which demonstrated the potential for reducing viscosity. The study examined the CO2 responsiveness of DA/TMPDA through the application of alternating CO2 and N2. It confirmed the reversible CO2 responsiveness of the surface activator. The results from the emulsification and viscosity reduction assessments suggest that the amalgamation of DA and TMPDA in a 1:1 molar ratio yielded a surfactant. This surfactant demonstrated favorable stability in water and heavy crude oil emulsions, as well as low viscosity and rapid emulsion breaking upon exposure to CO2. This investigation demonstrates that it is feasible to produce surfactants that are responsive to CO2 and possess the ability to reduce viscosity through a straightforward mixing process. This presents a viable approach to utilizing oligomeric surfactants that are CO2‐responsive for the purposes of emulsifying and breaking down heavy crude oil.

L-F001, a multifunctional fasudil-lipoic acid dimer, antagonizes hypoxic-ischemic brain damage by inhibiting the TLR4/MyD88 signaling pathway.

Neonatal hypoxic-ischemic brain damage (HIBD) is a serious inflammatory injury. At present, the standard treatment for this disease is hypothermia therapy, and the effect of drug intervention is still limited. L-F001 is a compound of fasudil and lipoic acid. Previous in vitro experiments have confirmed that L-F001 has anti-inflammatory neuroprotective functions. However, its therapeutic effect on neonates with HIBD remains unknown. This study was aimed at exploring the therapeutic effect of L-F001 on HIBD rats. The newborn rats were divided into three groups: Sham operation group, HIBD group, and HIBD+L-F001 group. HE staining, Nissil staining, the immunofluorescence of iNOS and COX-2, ELISA (IL-1β, IL-6, TNF-α, and IL-10), and western blotting analyses were performed to determine the therapeutic effect of L-F001. Finally, we evaluated the growth and development of each group by measuring body weight. The hippocampal structure of HIBD rats was disordered, and the Nissil body was small and shallow. The expressions of iNOS and COX-2 in HIBD rats were increased, whereas the expressions of IL-1β, IL-6, and TNF-α in plasma were upregulated, and the expression of IL-10 was decreased. L-F001 could improve the tissue structure and reduce the expression of iNOS and COX-2 in HIBD rats. Meanwhile, L-F001 could also reduce the expression of pro-inflammatory cytokines and restore the content of anti-inflammatory cytokines in plasma. We further found that the TLR4 pathway was activated after hypoxic-ischemia in neonatal rats. L-F001 could inhibit the activation of TLR4 pathway. Finally, we found that after L-F001 treatment, the body weight of HIBD rats increased significantly compared with the untreated group. L-F001 antagonizes the inflammatory response after hypoxic-ischemia by inhibiting the activation of the TLR4 signaling pathway, thus playing a neuroprotective role. L-F001 may be a potential therapeutic agent for neonatal HIBD.

Self-Assembly Mechanism and Analysis of Smectic Mesophase Induction in Binary Systems of 4-(4-Alkoxyphenylazo)benzonitriles and Dodecyloxybenzoic Acid

Using a combination of experimental methods (polarizing optical microscopy, IR spectroscopy), the two-component systems consisting of 4-dodecyloxybenzoic acid (BA) and 4-(4-alkoxyphenylazo)benzonitriles (BN-n, n = 8, 10, 12) have been studied. The mesophase existence ranges of the systems depending on the length of alkyl substituents of the component BN-n were established. The possibility of formation as well as stability of heterodimeric complexes with a hydrogen bond –COOH···NC – were analyzed by DFT/B97D/6-311++G** method. In all obtained equimolar BN-n:BA (1:1) systems SmA phase was induced, which manifests itself enantiotropically in wide temperature ranges. With the help of computer simulation, it was shown that, unlike homodimers, the expected BN···BA H-complex has an angular structure, which cannot ensure the formation of the SmA phase. To elucidate the mechanism of mesophase formation in BN-n:BA systems, we calculated the energies of intermolecular interaction in homo- and heterodimers, and analyzed the experimental IR spectra of equimolar BN-n:BA systems. The spectra represent a superposition of the spectra of associates BN···BN and cyclic dimers of acid BA···BA. Therefore, we suggest that the BN···BA type H-complexes cannot form in equimolar BN-n:BA mixtures. Instead, a structure consisting of alternating layers of BA···BA dimers and BN···BN associates is formed. The layers of the acid dimer play the main role in the formation of SmA phase. It is noted that –COOH group, in contrast to such proton-donor groups as –NH2, –NH–, –OH, does not form hydrogen bonds with the proton-acceptor –CN group.

Binding interaction of environmental DNA with typical emerging perfluoroalkyl acids and its impact on bioavailability

As the replacement compounds of perfluoroalkyl acids (PFAAs), emerging PFAAs generally exhibit equal or more hazardous toxicity than legacy PFAAs. Numerous DNA as environmental organic matters coexists with emerging PFAAs, but their interactions and the resulting interaction impacts on the bioavailability of emerging PFAAs remain insufficiently understood. Here, we studied the binding strength and mechanism between DNA and emerging PFAAs (perfluorobutyric acid, perfluorobutylsulfonic acid, and hexafluoropropylene oxide dimer acid) using perfluorooctanoic acid as the control, and further investigated the impacts of DNA binding on the bioavailability of the emerging PFAAs. Isothermal titration calorimetry and quantum chemical calculation found that the emerging PFAAs could bind with DNA bases (main thymine) by van der Waals force and halogen-bond, showing the binding affinities in the range of 7.87 × 104 to L/mol to 6.54 × 106 L/mol. The PFAAs-DNA binding significantly decreased the bioavailability of the PFAAs in both seedlings and plants of pakchoi (Brassica chinensis L.), with little differences in bioavailability change extent among PFAAs. The findings highlight the universality and similarity of the DNA binding effects on PFAAs bioavailability, which can be the natural detoxification mechanism for response to the PFAAs pollution.

Association of adverse fetal outcomes with placental inflammation after oral gestational exposure to hexafluoropropylene oxide dimer acid (GenX) in Sprague-Dawley rats

Hexafluoropropylene oxide dimer acid (HFPO-DA), known as “GenX” for its trade name, is gradually taking the place of Perfluorooctanoic acid (PFOA). However, there is a poor understanding of the developmental effects of GenX. This study aims to explore whether GenX produces adverse effects on offspring development in Sprague-Dawley (SD) rats and the underlying mechanisms. Pregnant rats were orally administered with GenX (0, 1, 10 and 100 mg/kg/day) from gestational 0.5–19.5 days. Experimental data showed that the exposure to GenX resulted in increased rats’ gestational weight gain, whereas both body weight and body length of their fetuses born naturally were significantly reduced. This could contribute to the developmental delays of fetal body weight, body length and tail length from postnatal 1–21 days. Histopathological evaluation of placenta indicated that GenX exposure led to neutrophil infiltration in decidual zone and congestion in labyrinth zone. Moreover, placental proteomics showed changes at the expression levels of the inflammation-related proteins in the Rap1 signaling pathway. In conclusion, gestational exposure to GenX induced fetal intrauterine and extrauterine development retardation in SD rats. Placental inflammation may play a key role in this process through the Rap1 signaling pathway.

Ultrafast Proton Transfer and Contact Ion-Pair Formation in Formic Acid Clusters.

The ultrafast proton transfer dynamics of homogeneous formic acid clusters (FA)n, n < 10, are investigated with femtosecond time-resolved mass spectrometry. We monitor the proton transfer pathway following Rydberg state electronic relaxation and find that successful ion pair formation increases logarithmically with cluster size. Ab initio calculations demonstrate similar excitation/relaxation behavior for each cluster, revealing a contact ion pair forms between two molecules composing the cluster before finally a formate anion (HCOO-) is dissociated by the probe pulse. The sub-ps time scale for rearrangement and proton transfer increases almost linearly with cluster size, requiring ∼67 fs per additional formic acid molecule and ranging from 213 ± 51 fs for the trimer to 667 ± 116 fs for FA9. The near-linear trends measured for both rearrangement lifetime and ion pair formation suggest that proton transfer is unlikely in the formic acid dimer but becomes prominent in small clusters.

Carrier-Free Gambogic Acid Dimer Self-Assembly Nanomedicines for Rheumatoid Arthritis Treatment.

The insufficient targeting delivery of therapeutic agents greatly impeded the treatment outcomes of rheumatoid arthritis (RA). Despite the recognized therapeutic advantages of gambogic acid (GBA) in inflammatory diseases, its high delivery efficiency to inflammatory site still limits its clinical application. Self-assembly of drug dimers into carrier-free nanoparticles (NPs) has become a straightforward and attractive approach to develop nanomedicines for RA treatment. Herein, homodimers of GBA were designed to form the carrier-free NPs by self-assembly for RA treatment. The synthetic gambogic acid dimers (GBA2) were self-assembled into NPs using a one-step solvent evaporation method. The size distribution, morphology, drug-loading efficiency (DLE) and storage stability were evaluated. A molecular dynamic simulation was conducted to gain further insight into the self-assembly mechanisms of GBA2/NPs. Besides, we investigated the cytotoxicity, apoptosis and cellular uptake profiles of GBA2/NPs in macrophages and osteoclasts. Finally, the specific biodistribution on the ankles of adjuvant-induced arthritis (AIA) mice, and the anti-RA efficacy of the AIA rat model were assessed. GBA2/NPs exhibited the uniform spherical structure, possessing excellent colloidal stability, high self-assembly stability, high drug loading and low hemolytic activity. Comparing with GBA, GBA2/NPs showed higher cytotoxicity, cellular uptake and apoptosis rate against osteoclasts. In addition, GBA2/NPs exhibited much higher accumulation in ankle joints in vivo. As expected, the systematic administration of GBA2/NPs resulted in the greater alleviation of arthritic symptoms, cartilage protection, and inflammation, notably the reduced systemic toxicity compared to free GBA. GBA2/NPs formed GBA dimers exhibited the superior accumulation in the inflamed joint and anti-RA activity, potentially attributing to the similar extravasation through leaky vasculature and subsequent inflammatory cell-mediated sequestration ("ELVIS") effects in inflamed joint and the enhanced cellular uptake in macrophages and osteoclasts. Our findings provide substantial evidence that self-assembly of GBA2/NPs would be a promising therapeutic alternative for RA treatment.

Profiling of primary and phytonutrients in edible mahlab cherry (Prunus mahaleb L.) seeds in the context of its different cultivars and roasting as analyzed using molecular networking and chemometric tools.

Prunus mahaleb L. (mahlab cherry) is a deciduous plant that is native to the Mediterranean region and central Europe with a myriad of medicinal, culinary and cosmetic uses. The present study explored different cultivars of mahlab (white from Egypt and Greece, red from Egypt and post roasting). UPLC-MS led to the detection of 110 primary and secondary metabolites belonging to different classes including phenylpropanoids (hydroxy cinnamates, coumaroyl derivatives), organic acids, coumarins, cyanogenic glycosides, flavonoids, nitrogenous compounds, amino acids and fatty acids, of which 39 are first time to be detected in Prunus mahaleb L. A holistic assessment of metabolites was performed for further analysis of dataset using principal component analysis (PCA) among mahlab cultivars to assess variance within seeds. The results revealed that phenolic acids (coumaric acid-O-hexoside, ferulic acid-O-hexoside, ferulic acid-O-hexoside dimer, dihydrocoumaroyl-O-hexoside dimer and ferulic acid), coumarins (coumarin and herniarin) and amino acids (pyroglutamic acid) were abundant in white mahlab cultivars (cvs.) from different locations. In contrast, red mahlab and its roasted seeds were more rich in organic acids (citric and malic acids), amygdalin derivative and sphingolipids. Orthogonal projections to latent structures discriminant analysis (OPLS-DA) revealed for markers in red mahlab and in response to roasting, where red mahlab was rich in nitrogenous compounds viz. nonamide, deoxy fructosyl leucine, glutaryl carnitine and isoleucine, while roasted product (REM) was found to be enriched in choline.

Synthesis of lactide from L-Lactic acid over iso-reticular zeolites derived from Al-UTL

Controlling the reaction selectivity by use of rationally designed catalysts provides high yields of desired products rendering the process more efficient and sustainable. In this study, we investigated a series of isoreticular zeolites (Al-IPC-n, n = 2, 4, 6, and 7), in the synthesis of lactide from L-Lactic acid as an intermediate for the polylactic acid production. Catalytic tests allowed a thorough understanding of the structure-acidity-activity relationship and the control of the shape selectivity. The lactide and the dimers of the lactic acid were obtained in one step with a high selectivity (>55% for lactide and >70% for the dimer of the lactic). The selectivity to L,L-lactide was comparable with that on more acidic commercial BEA. A balance between the acidity and the pore size afforded high yields of the dimer, avoiding the poisoning of the catalyst and the production of the larger oligomers.

Activation of estrogen-related receptor: An alternative mechanism of hexafluoropropylene oxide homologs estrogenic effects

Perfluorooctanoic acid (PFOA) alternatives such as hexafluoropropylene oxide homologs (HFPOs) cause concern due to increased occurrence in the environment as well as potential bioaccumulation and toxicity. HFPOs have been demonstrated to activate the estrogen receptor (ER) pathway. The ER pathway is homologous and connected to the estrogen-related receptor (ERR) pathway, but HFPOs effects on the ERR pathway have not been studied. Hence, we assessed the potential estrogenic effects of HFPOs via ERRγ pathway. In vitro assays revealed that HFPO dimeric, trimeric, and tetrameric acids (HFPO-DA, −TA, and -TeA, respectively), acted as ERRγ agonists, activating the transcription of both human and zebrafish ERRγ at low concentrations, but inhibiting zebrafish ERRγ at high concentrations. We also found that HFPO-TA promoted the human endometrial cancer cells (Ishikawa cells) proliferation via ERRγ/EGF, Cyclin D1 pathway. The HFPO-TA-induced proliferation of Ishikawa cells was inhibited by co-exposure with a specific antagonist of ERRγ, GSK5182. In vivo exposure of female zebrafish to HFPO-TA disturbed sex hormone levels, interfered with the gene expression involved in estrogen synthesis and follicle regulation, and caused histopathological lesions in the ovaries, which were similar to those induced by a known ERRγ agonist GSK4716. Taken together, this study revealed a new mechanism concerning the estrogenic effect of HFPOs via activation of the ERRγ pathway.

Toxicity comparison of perfluorooctanoic acid (PFOA), hexafluoropropylene oxide dimer acid (HFPO-DA), and hexafluoropropylene oxide trimer acid (HFPO-TA) in zebrafish gut

Hexafluoropropylene oxide dimer acid (HFPO-DA) and hexafluoropropylene oxide trimer acid (HFPO-TA) are considered as alternatives to perfluorooctanoic acid (PFOA). In this study, zebrafish were exposed to different concentrations of PFOA, HFPO-DA, and HFPO-TA (5 μg/L and 500 μg/L), and the toxic effects on oxidative damage, inflammation, and cell apoptosis in the gut were compared. Additionally, changes in gut metabolome profiles and microbial community structure were analyzed. The results revealed that exposures to HFPO-DA and HFPO-TA led to lower levels of oxidative damage compared to PFOA exposure. However, all three treatments had comparable effects on inflammation and apoptosis. The main biological pathways affected by all three exposures were lipid metabolism, nucleotide metabolism, amino acid metabolism, and environmental information processing. The effects on metabolome profiles were much higher for HFPO-DA and HFPO-TA compared to PFOA at a concentration of 5 μg/L. At a concentration of 500 μg/L, HFPO-DA and HFPO-TA showed similar effects to PFOA. This study also examined the Pearson correlations between gut microbiota and the toxic effects mentioned above. The abundance of specific apoptosis-related genera differed among the three target chemicals, suggesting they may act differently in inducing apoptosis. The correlations between HFPO-DA and HFPO-TA were mostly similar, which helps explain the similar effects observed in their respective treatment groups on metabolic profiles. Overall, this study indicates that HFPO-DA and HFPO-TA may not be safe alternatives to PFOA and provides valuable insights into their toxic effects and risk assessment in water environments.

Conformational polymorphism of 3-(azidomethyl)benzoic acid

Three conformational polymorphs of 3-(azidomethyl)benzoic acid, C8H7N3O2, are reported. All three structures maintain similar carboxylic acid dimers and π–π stacking. Crystal structure analysis and computational evaluations highlight the azidomethyl group as a source of conformational polymorphism, thus having potential implications in the design of solid-state reactions.

Chemistry of Dimer Acid Production from Fatty Acids and the Structure-Property Relationships of Polyamides Made from These Dimer Acids.

While there is abundant literature on using a wide range of biomaterials to make polymers for various adhesive applications, most researchers have generally overlooked developing new adhesives from commercially available bio-based dimerized fatty acids. Some of the literature on the chemistry taking place during the clay-catalyzed dimerization of unsaturated fatty acids is generally misleading in that the mechanisms are not consistent with the structures of these dimers and a by-product isostearic acid. A selective acid-catalyzed interlayer model is much more logical than the widely accepted model of clay-catalyzed Diels-Alder reactions. The resulting dimers have a variety of linkages limiting large crystal formation either as oligomeric amides or polyamides. These highly aliphatic fatty acid dimers are used to make a wide range of hot melt polyamide adhesives. The specific structures and amounts of the diacids and diamines and their relative ratios have a big effect on the bio-based polyamide mechanical properties, but analysis of the structure-property relationships has seldom been attempted, since the data are mainly in the patent literature. The diacids derived from plant oils are valuable for making polyamides because of their very high bio-based content and highly tunable properties.

Study on Blending Modification of Bisphenol A Epoxy.

Epoxy-resin-based composites in the field of current electrical materials often work in high temperature, high humidity or salt spray conditions. In order to improve the operation reliability of the composite insulator cross arm in a high temperature, high humidity and high salt spray environment, and analyze the aging mechanism and performance characteristics of resin, in this paper, wet heat aging and salt spray aging experiments were carried out on the blended resin system composed of bisphenol A type epoxy resin (E-51), aliphatic epoxy modified bisphenol A epoxy resin (2021P/E-51) and dimeric acid modified bisphenol A epoxy resin (EPD-172/E-51). Among them, 10 wt% and 20 wt% of 2021P blend resin and 10 wt% of EPD blend resin have superior thermo-mechanical properties. Under humid and hot conditions, the dielectric loss of 10 wt% EPD blend system before and after aging is 39.9% and 49.5% lower than that of pure E51 resin system, respectively. Under the condition of salt spray, the dielectric loss of 20 wt% and 10 wt% EPD blends decreased by 73.1% and 74.6% after aging. The leakage current of 10 wt% 2021P blend resin and 10 wt% EPD blend resin decreased by 7% and 3.8% before aging, respectively. After aging, they decreased by 3.7% and 2.2%, respectively. The bending strength of 2021P blend resin before and after aging reached 29.3 MPa and 26.6 MPa, respectively. The above three blending resin systems exhibit good electrical properties and good mechanical properties, their ageing resistance performance is strong and they are suitable as the matrix resin of compound cross arm mandrel material.

Antinociceptive effect of cyclic and linear diterpenoids as new atypical agonists of κ-opioid receptors obtained from four species of the Baccharis genus, and vehiculated in nanometric niosomes

New natural analgesic compounds that act in KORs are important alternatives for potential therapeutical use in medicine. In this work, we report and compare here the antinociceptive activity displayed by cyclic and linear diterpenes, obtained from the genus Baccharis. The antinociceptive activities determined were relatively strong, in comparison whit morphine. The antinociceptive mechanism of action was made through naloxone administration (a non-selective antagonist of opioid receptors). The more active compounds were vehiculized successfully in niosomes at nanometric scale. The observed antinociceptive activity for Bartemidiolide oxide (BARTO), obtain from Baccharis artemisioides, was greater than Flabeloic acid dimer (DACD), the first compound isolated from Baccharis flabellata that was reported possessing antinociceptive effects. We also conducted docking calculations and molecular dynamics simulations, which suggested that the newly identified diterpenes might share the molecular action mechanism reported for Salvinorin A (SalA). Molecular simulations have allowed us to appreciate some subtle differences between molecular interactions of these ligands stabilizing their respective complexes; such information might be useful for designing and searching for new inhibitors of KORs.

New insights into the degradation mechanism and risk assessment of HFPO-DA by advanced oxidation processes based on activated persulfate in aqueous solutions

Hexafluoropropylene oxide dimer acid (HFPO-DA) is widely used as a substitute for perfluorooctanoic acid (PFOA). HFPO-DA exhibits high water solubility and low adsorption potential, conferring significant fluidity in aquatic environments. Given that the toxicity of HFPO-DA is similar to PFOA, it is necessary to control its content in aquatic environments. Electrochemical and thermally-activated persulfates have been successfully used to degrade HFPO-DA, but UV-activated persulfates cannot degrade the compound. Given that research on degradation mechanisms is still incomplete and lacks kinetic research, the mechanism and kinetic calculations of oxidative degradation were studied in detail using DFT calculations. And the toxicity of HFPO-DA degradation intermediates and products was evaluated to reveal the feasibility of using advanced oxidation process (AOP) technology based on persulfate to degrade HFPO-DA in wastewater. The results showed that the committed step of HFPO-DA degradation was initiated by the electron transfer reaction of SO4•- radicals. This reaction is not spontaneous at room temperature and requires sufficient electrical or thermal energy to be absorbed from the external environment. The perfluoroalcohol produced during this reaction can subsequently undergo four possible reactions: H atom abstraction from alcohol groups by an OH radical; H atom abstraction by SO4•-; direct HF removal; and HF removal with water as the catalyst. The final degradation products of HFPO-DA mainly include CO2, CF3CF2COOH, CF3COOH, FCOOH and HF, which has been identified through previous experimental analysis. Ecotoxicity assessment indicates that degradation does not produce highly toxic intermediates, and that the final products are non-toxic, supporting the feasibility of persulfate-based AOP technologies.

Electrochemical detection of fluoride ions using 4-aminophenyl boronic acid dimer modified electrode

Fluoride is a widely used component in dental products, offering benefits such as cavity prevention through bacterial growth inhibition. However, excessive fluoride consumption can lead to fluorosis, which causes tooth discoloration and pitting, and in severe cases, skeletal fluorosis with joint pain and stiffness. Therefore, monitoring fluoride levels in dental products and drinking water is essential. In this study, we developed a rapid electrochemical detection method for fluoride ions using a preanodized screen-printed carbon electrode modified with 4-aminophenylboronic acid dimer (SPCE*/APBAD). The preanodization process involved applying a constant potential of +2 V for 5 min to capture APBAD. The resulting APBAD facilitated a chemical reaction between fluoride ions and boronic acid, forming a fluorophenylboronate complex. This complexation reaction enabled the detection of fluoride ions in a wide linear range (5 µM to 30 mM) with a detection limit of 0.3 µM. The detection behaviour of fluoride ion using SPCE*/APBAD has been studied using cyclic voltammetry, potentiometry, Density Functional Theoretical calculations and flow injection analysis. Furthermore, the practical utility of the sensor was validated by successfully detecting fluoride ions in toothpaste and water samples. The developed method offers a rapid and reliable means of monitoring fluoride ion levels for ensuring safe and beneficial use in dental products and drinking water.

Effect of Preparation Conditions on Crosslinking Behavior of Linseed Oil-Based Thermosetting Polymer

Bio-based materials have received more attention to replace materials from petroleum resources because of sustainability reason. Plant oil is one of the most interesting raw materials to produce thermosetting polymer. A crosslinking reaction between epoxidized linseed oil and vegetable oil-based crosslinkers is investigated in present study. Two types of crosslinker including fatty acid dimer and fatty acid trimer were reacted with epoxidized linseed oil. A rotational rheometer equipped with cone-and-plate geometry was used to monitor the progress of three-dimensional network formation. A curing phenomenon was illustrated by the increment in storage modulus of the reaction mixture. The trifunctional crosslinker was more effective than difunctional crosslinker for an uncatalyzed systems at the reaction temperature of 120 OC. When the crosslinking temperature of trimer-crosslinker system increased from 120 OC to 140 OC, the induction time for curing decreased around three times. The reaction between epoxidized oil and trimer acid was obviously accelerated by using 4-methyl amino pyridine as a catalyst. Increasing the catalyst content induced a monotonically reduction in induction time of curing process. The induction time of the reaction between epoxidized linseed oil and trimer acid with 2% catalyst at reaction temperature of 120 OC was only 18 minutes, which was significantly shorter than that of an uncatalyzed systems around seven times.

Generalized Nuclear-Electronic Orbital Multistate Density Functional Theory for Multiple Proton Transfer Processes.

Proton transfer and hydrogen tunneling play pivotal roles in many chemical and biological processes. The nuclear-electronic orbital multistate density functional theory (NEO-MSDFT) approach was developed to describe hydrogen tunneling systems within the multicomponent NEO framework, where the transferring proton is quantized and treated with molecular orbital techniques on the same level as the electrons. Herein, the NEO-MSDFT framework is generalized to an arbitrary number of quantum protons to allow applications to systems involving the transfer and tunneling of multiple protons. The generalized NEO-MSDFT approach is shown to produce delocalized, bilobal proton densities and accurate tunneling splittings for fixed geometries of the formic acid dimer and asymmetric substituted variants, as well as the porphycene molecule. Investigation of a protonated water chain highlights the applicability of this approach to proton relay systems. This work provides the foundation for nuclear-electronic quantum dynamics simulations of a wide range of multiple proton transfer processes.