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This paper describes the hydrodynamic behavior of superparamagnetic iron oxide nanoparticles modified with citric acid (CA-SPIONs) in suspension under alternating current magnetic fields given interparticle and inter-cluster dipole–dipole interactions. The cluster size of the CA-SPIONs is modulated to control interparticle interactions, and the ionic concentration of the CA-SPION suspension is varied to control inter-cluster interactions. Dynamic magnetic susceptibility (DMS) measurements of the CA-SPION suspensions under alternating current magnetic fields indicate that the interparticle interaction by clustering and the inter-cluster interaction by increasing the ionic concentration cause frequency spectra modulation, such as their broadening in the low-frequency region and a decrease in the Brownian relaxation frequency. The experimentally obtained DMS spectra differ from the spectra numerically calculated from the hydrodynamic size distribution of CA-SPIONs using the Debye relaxation model without considering the magnetic interactions; the differences are attributed to the interparticle and inter-cluster dipole–dipole interactions. These insights contribute to a deeper understanding of dynamics of superparamagnetic iron oxide nanoparticles and facilitate nanoparticle parameter optimization for tailored applications in the biomedical field, particularly for their efficacy and precision in liquid-phase biosensing and imaging. [ABSTRACT FROM AUTHOR]

In this study, a wound-healing membrane was fabricated based on carboxymethyl cellulose (CMC) and polyethylene glycol (PEG) containing curcumin (Cur) and bromelain (Br). Citric acid (CA) was used as a cross-linking agent. This membrane showed an ideal degree of swelling, which was significantly dependent on the concentration and duration of cross-linked CA. The chemical characterization showed the CA cross-linker mechanism was more associated with chemical reactions with CMC carboxyl groups, and PEG hydroxyl groups played an important role in forming a hybrid polymer network. It greatly enhanced mechanical and adhesive properties, so the stress strength was improved from 29.4 to 38.52 Mpa. The hydrophilicity of the membrane surface according to the water contact angle assay showed the membrane surface is suitable for adhesion, growth, migration, and proliferation of skin cells. The drug delivery assay demonstrated that the Br and Cur were released during 48 h, but the Br followed the burst release in comparison with Cur. Antibacterial properties showed that CMC/PEG-Cur/Br have ideal antibacterial properties for preventing the growth of bacteria. In summary, the engineered CMC/PEG containing Cur/Br films with desired cell viability properties and antibacterial activity can potentially improve and accelerate skin regeneration for chronic wound healing. Highlights * Hydrogel film was prepared based on carboxymethyl cellulose (CMC), polyethylene glycol (PEG), and citric acid as cross-linking agent. * CMC/PEG film were induced controlling curcumin (Cur) and bromelain (Br) release for wound healing process. * CMC/PEG film revealed a wide range of physiochemical, mechanical, adhesion, and biological properties behavior. * Incorporation of Cur and Br promoted in vitro biocompatibility, L-929 cells attachments, and cell migration. KEYWORDS antibacterial properties, bromelain, carboxymethyl cellulose, curcumin, drug delivery, polyethylene glycol, wound dressing, 1 | INTRODUCTION As the largest human tissue, the skin serves a crucial role as a barrier against infection. (1) Due to an incomplete physical barrier and exposed subcutaneous tissue, [...]

The removal of Congo red (CR) and heavy metal ion nickel (Ni(II)) from wastewater is a critical concern for safeguarding the aquatic environment and promoting sustainable development. Herein, a novel citric acid steam-assisted decomposition method is applied to form meso-macroporous magnesium oxide (MgO) with rich oxygen defects. As the gelation process of xerogel precursor could be significantly promoted by the steam-assisted process with citric acid solution as steam source, the morphology structure of MgO changes into loose aggregates with sharp edges and is covered by a layer of MgO nanoparticles. The synthesized MgO, with a high surface area (103.60 m2 g−1), meso-macroporous structure and abundant oxygen defects, exhibits super adsorption capacities for CR (7109.85 mg g−1) and Ni(II) (1405.88 mg g−1). The MgO (0.4 g L−1) could completely remove CR (200 mg L−1) in 30 min, while 10 min for Ni(II) (200 mg L−1) adsorption. The adsorption mechanism of MgO for CR and Ni(II), including electrostatic interaction, oxygen vacancy capture, hydrogen bonding and ion exchange, is effectively enhanced due to the appearance of meso-macroporous structure and oxide defects, such as 5-coordinated oxygen anion (O 5C 2−) for terrace, 4-coordinated oxygen anion (O 4C 2−) for edge and 3-coordinated oxygen anion (O 3C 2−) for corner. The easy calcination is applied to recycle MgO after CR adsorption and the CR removal efficiencies are above 98 % after five cycles. Meanwhile, a nickel chelator (Na 2 EDTA) and calcination are used to regenerate the MgO after Ni(II) adsorption and the adsorbent shows an insignificant removal efficiency loss after three cycles. The meso-macroporous MgO with rich oxygen defects has the characteristics of high adsorption speed, high adsorption capacity and convenient recovery property, and is expected to become an ideal material for the rapid treatment of high concentration wastewater. [ABSTRACT FROM AUTHOR]

In this study, hydroxypropyl cellulose (HPC) was utilized as the raw material, with the addition of β-cyclodextrin (β-CD), citric acid (CA) as the crosslinking agent, and sodium hypophosphite (SHP) as the catalyst to produce hydroxypropyl cellulose/β-CD composite films. The inclusion of β-CD resulted in an increase in the tensile strength of the film, with the maximum value of 13.5 MPa for the 1 % β-CD composite membrane. Additionally, after degradation in soil for 28 days, the degradation ability was significantly enhanced, with the 1.0 % β-CD composite film exhibiting the highest degradation rate of 27.21 %. Furthermore, the water permeability of the composite membrane was improved with the addition of β-CD. Specifically, when the β-CD content was 1.0 %, the water vapor transmission reached its lowest point at 2,445 g* (m 2 * 24 d) − 1 . The findings demonstrated that the 1 % β-cyclodextrin/hydroxypropyl cellulose composite film effectively preserved the freshness of strawberries, reducing the weight loss rate by 1.65 % compared to the control group. In conclusion, this research highlights the potential for preparing composite membranes using HPC and β-CD crosslinking, thereby expanding the application of hydroxypropyl cellulose and β-CD in food preservation. [ABSTRACT FROM AUTHOR]

In this work, new pH‐sensitive and antibacterial drug carrier systems based on silver nanoparticles (AgNPs) embedded in the interlayer of laponite (Lap) in the presence of chitosan (CTS) for the controllable release of sunitinib maleate (STM) were developed. Silver ions and sunitinib maleate were first loaded into Lap, and the CTS‐based hybrid bionanocomposite carrier (Lap@CTS@AgNPs@STM) was obtained in the presence of citric acid as a cross‐linker agent. The successful preparation of nanocarrier and Ag NPs formation was thoroughly confirmed using techniques such as FTIR, XRD, TGA, SEM, and TEM. TEM images illustrated the excellent distribution of Ag NPs in the structure of Lap@CTS@AgNPs. The as‐prepared samples showed a pH‐sensitive anticancer drug release behavior. The STM release mechanism was studied using Korsmeyer–Peppas and Higuchi kinetic models. Furthermore, the in vitro cytotoxicity and antibacterial tests were carried out against both bacteria S. aureus and E. coli and MCF‐7 cell lines, respectively, to prove the effectiveness of synthesized samples as multifunctional carrier systems for biomedical applications. [ABSTRACT FROM AUTHOR]

This study aimed to enhance compatibility and thermal stability between thermoplastic starch (TPS) and polylactic acid (PLA) by incorporating citric acid-grafted starch (CA–Starch) at different concentrations (1 and 5%) with varying degrees of substitution for starch derived from sweet potatoes and yams (DY). Blends were produced using a constant TPS/PLA weight ratio of 60:40, both with and without a compatibilizer. The blending process was carried out using a torque rheometer under two distinct conditions. The results exhibited reduced particle sizes in TPS60/PLA40/CA–Starch blends, as evidenced by SEM images displaying improved interaction and smoother surfaces. Significantly, one of the properties that experienced substantial improvement was the compatibility between TPS and PLA, as indicated by reduced phase segregation within the blends. This improvement manifested in enhanced surface morphology, smaller particle sizes, and greater homogeneity in the blends. Additionally, an enhancement in thermal properties, particularly thermal stability, was observed with higher CA content. This study underscores that the incorporation of CA–Starch not only enhances compatibility but also improves thermal stability in TPS60/PLA40 blends, offering potential for the development of biocompatible materials with superior performance. [ABSTRACT FROM AUTHOR]

The main objective of this study was to develop a citric acid-catalyzed hydrothermal pretreatment to reach the maximum sugar recovery from soybean hull (SH), in the context of a biorefi nery concept. A central composite design (CCD) was used to optimize pretreatment conditions through the analysis of citric acid concentration, time, and temperature effects. Optimized conditions were defined as 3.56% w/w, 46.1 min, and 135.7 °C. From the solid fraction, 99.5% and 83.0% of glucose and xylose conversion, respectively, were obtained after enzymatic hydrolysis. Sugars were fermented successfully to L-lactic acid by Lactobacillus pentosus. In fact, SH hydrolysate presented no trace of inhibitor compounds, and glucose was totally consumed during fermentation. After 24 h of fermentation, a conversion rate of 0.724 g/g of sugars to lactic acid and 80.5% of the stoichiometric theoretical yield were reached. In addition, from the liquid fraction, 47.8 mg/g of xylooligosaccharides (XOS) was produced. This work demonstrates the potential of SH to be exploited as feedstock, with mild and efficient pretreatment process, for medium- to high-value bioproducts production in biorefineries. [ABSTRACT FROM AUTHOR]

We report the use of novel biobased plasticizers prepared starting from citric acid (CA) in polylactic acid (PLA). Citric acid based plasticizers are well-known softeners for PLA, with citrate esters as the most commonly used class. However, citrate esters are known to leach out of the plastic material over time. This problem is currently addressed by acetylating the tertiary hydroxyl group of citric acid via complex and environmentally polluting processes. An alternative strategy consists in the reductive removal of the tertiary hydroxyl group, resulting in propane-1,2,3-tricarboxylic acid. Derivatizing this compound leads to novel plasticizers which have not been tested in PLA yet. Here, different esters of propane-1,2,3-tricarboxylic acid were synthesized and blended in PLA. Their influence on the thermal (Tg and Tm) and the mechanical properties (Young's modulus, stress and strain) of PLA along with their migration out of the material were compared to those of commercially available citric acid based plasticizers. Our results show that similar or better results were obtained with these new PLA plasticizers. [ABSTRACT FROM AUTHOR]

Highly acidic citrus pomace (CP) is a byproduct of Pericarpium Citri Reticulatae production and causes significant environmental damage. In this study, a newly isolated acid-tolerant strain of Serratia sp. JS-043 was used to treat CP and evaluate the effect of reduced acid citrus pomace (RACP) in passivating heavy metals. The results showed that biological treatment could remove 97.56% of citric acid in CP, the organic matter in the soil increased by 202.60% and the catalase activity in the soil increased from 0 to 0.117 U g−1. Adding RACP into soil can increase the stabilization of Cu, Zn, As, Co, and Pb. Specifically, through the metabolism of strain JS-043, RACP was also involved in the stabilization of Zn and Pb, and Residual Fraction in the total pool of these metals increased by 10.73% and 10.54%, respectively. Finally, the genome sequence of Serratia sp. JS-043 was completed, and the genetic basis of its acid-resistant and acid-reducing characteristics was preliminarily revealed. JS-043 also contains many genes encoding proteins associated with heavy metal ion tolerance and transport. These findings suggest that JS-043 may be a high-potential strain to improve the quality of acidic organic wastes that can then be useful for soil bioremediation. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of solutions containing aminomethacrylate copolymer (AA) and sodium fluoride (F; 225 ppm F−) or fluoride plus stannous chloride (FSn; 225 ppm F−, 800 ppm Sn2+) against enamel and dentin erosion/abrasion. Solutions F, FSn, AA, F+AA, FSn+AA, and deionized water as negative control were tested. Bovine enamel and dentin specimens (n = 13/solution/substrate) underwent a set of erosion‐abrasion cycles (0.3% citric acid [5 min, 4×/day], human saliva [1 h, 4×/day], brushing [15 s, 2×/day], and treatments [2 min, 2×/day]) for each of five days. Initial enamel erosion was evaluated using Knoop microhardness after the first and second acid challenge on day 1, and surface loss with profilometry after day 5. KOH‐soluble fluoride was assessed. Data were analyzed with ANOVA/Tukey tests. The combination of fluoride and AA resulted in higher protection against enamel erosion, whereas this was not the case for the combination of AA and FSn. All treatments protected against enamel and dentin loss. The lowest surface loss values were observed with F+AA and FSn+AA. The polymer did not significantly influence the KOH‐soluble fluoride formation on enamel/dentin specimens. The aminomethacrylate copolymer effectively enhanced the efficacy of sodium fluoride against initial erosion and improved the control of enamel and dentin wear of F and FSn solutions. [ABSTRACT FROM AUTHOR]

In this paper, nitrogen-doped carbon quantum dots (N-CQDs) were prepared by using citric acid as a carbon source and ethylenediamine as a nitrogen source. Then, N-CQDs were added into a deep eutectic solvent (DES) synthesized from acrylamide (AM), urea (U), and choline chloride (ChCl). The N-CQDs/P(AM-U-ChCl) composite hydrogels were prepared by light polymerization. The chemical composition and microstructure of N-CQDs/P(AM-U-ChCl) composite hydrogels were characterized in detail using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). This article further explored the influence of the content of N-CQDs on the mechanical properties, adsorption properties, and detection performance of the composite hydrogel. The results showed that the composite hydrogels exhibited the best mechanical properties when N-CQDs' content was 0.3 wt%. The adsorption performance of N-CQDs/P(AM-U-ChCl) composite hydrogels for Fe3+ was significantly enhanced due to the carboxyl groups contained in N-CQDs. In detecting tert-butylhydroquinone (TBHQ), the composite hydrogel showed a good linear correlation in the concentration range of 0–200 mg L−1, and the detection limit of TBHQ reached 0.849 mg L−1. This study provides a new idea for preparing composite hydrogel materials with excellent mechanical properties and functionality. Also, it demonstrates their potential application value in heavy metal ion adsorption and organic molecule detection. [ABSTRACT FROM AUTHOR]

Introduction: Selenium (Se) plays a vital role in various physiological processes in plants and is regarded as an essential micronutrient for human health as well. Methods: In this study, sodium selenite solution at 10, 40, 70, and 100 mg·L-1 concentrations was foliar sprayed, and the strawberry plant growth, antioxidant system, and fruit quality with an emphasis on sugar and acid content were assessed. Results: The results showed that 10 mg·L-1 of sodium selenite treatment promoted plant growth, while all the treated concentrations could enhance photosynthesis, the antioxidant system in leaves, the content of Se, and ascorbic acid in fruits. More importantly, 40 mg·L-1 sodium selenite treatment significantly increased fruit weight, total soluble solid, total phenolic content, and anthocyanins, as well as improved the shape index. Furthermore, it decreased the total flavonoid and proanthocyanidin content. Particularly, sodium selenite treatment at 40 and 70 mg·L-1 largely increased the ratio of soluble sugars to titratable acid. The changes of predominant sugars and organic acids during fruit development were further investigated. The sucrose, fructose, and glucose content was upregulated by sodium selenite treatment through upregulating the activities of sucrose phosphate synthase (SPS) and acid invertase, as well as the FaSPS expression. In addition, sodium selenite treatment inhibited the activity of citrate synthase and phosphoenolpyruvate carboxylase, rather than modulating their transcript levels to reduce the citric acid content. Conclusions: This work presented a potentially efficient approach to enhance plant growth and fruit quality and supplement Se in strawberry, providing insights into the mechanism of regulating sugar and acid metabolism by Se. [ABSTRACT FROM AUTHOR]

Background: Abiotic stress seriously affects the growth and yield of crops. It is necessary to search and utilize novel abiotic stress resistant genes for 2.0 breeding programme in quinoa. In this study, the impact of drought stress on glucose metabolism were investigated through transcriptomic and metabolomic analyses in quinoa seeds. Candidate drought tolerance genes on glucose metabolism pathway were verified by qRT-PCR combined with yeast expression system. Results: From 70 quinoa germplasms, drought tolerant material M059 and drought sensitive material M024 were selected by comprehensive evaluation of drought resistance. 7042 differentially expressed genes (DEGs) were indentified through transcriptomic analyses. Gene Ontology (GO) analysis revealed that these DEGs were closely related to carbohydrate metabolic process, phosphorus-containing groups, and intracellular membrane-bounded organelles. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis detected that DEGs were related to pathways involving carbohydrate metabolisms, glycolysis and gluconeogenesis. Twelve key differentially accumulated metabolites (DAMs), (D-galactose, UDP-glucose, succinate, inositol, D-galactose, D-fructose-6-phosphate, D-glucose-6-phosphate, D-glucose-1-phosphate, dihydroxyacetone phosphate, ribulose-5-phosphate, citric acid and L-malate), and ten key candidate DEGs (CqAGAL2, CqINV, CqFrK7, CqCELB, Cqbg1x, CqFBP, CqALDO, CqPGM, CqIDH3, and CqSDH) involved in drought response were identified. CqSDH, CqAGAL2, and Cqβ-GAL13 were candidate genes that have been validated in both transcriptomics and yeast expression screen system. Conclusion: These findings provide a foundation for elucidating the molecular regulatory mechanisms governing glucose metabolism in quinoa seeds under drought stress, providing insights for future research exploring responses to drought stress in quinoa. [ABSTRACT FROM AUTHOR]

The main objective of this work is to synthesize multifunctional nanodendritic structural molecules that can effectively encapsulate hydrophilic as well as hydrophobic therapeutic agents. Four different types of fourth-generation lysine-citric acid based dendrimer have been synthesized in this work: PE-MC-Lys-CA-PEG, TMP-MC-Lys-CA-PEG, PE-MS-Lys-CA-PEG, and TMP-MS-Lys-CA-PEG. The antibacterial drug cefotaxime (CFTX) was further conjugated to these dendrimers. The dendrimer and drug-dendrimer conjugate structures were characterized with the help of FTIR,1H-NMR, and 13C-NMR spectroscopy. Zeta sizer, AFM, and HR-TEM techniques were used to investigate the particle size, surface topography, and structural characteristics of drug-dendrimer conjugates. In vitro drug release was then investigated using dialysis method. Various kinetic drug release models were examined to evaluate the type of kinetic drug release mechanism of the formulations. Cytotoxicity study revealed that the dendrimers encapsulated with CFTX exhibited 2-3% toxicity against healthy epithelial cells, indicating their safe use. Plain dendrimers show 10-15% hemolytic toxicity against red blood cells (RBC), and the toxicity was reduced to 2-3% when CFTX was conjugated to the same dendrimers. The 3rd and 4th generation synthesized drug-dendrimer conjugates exhibit a significantly effective zone of inhibition (ZOI) against both Gram-positive and Gram-negative bacteria. For Gram-positive bacteria, the lower concentration of 0.1 mg/mL showed more than 98% inhibition of drug-dendrimer conjugate samples against B. subtilis and more than 50% inhibition against S. aureus using 0.2 mg/mL, respectively. Moreover, samples with concentrations of 0.5 and 1.0 mg/mL exhibited more than 50% inhibition against S. typhimurium and E. coli, respectively. [ABSTRACT FROM AUTHOR]

Liquid-phase sintering anorthite (LSA) glass-ceramics with degradation in citric-acid solution have been prepared from CaO–Al 2 O 3 –SiO 2 –B 2 O 3 low-melting compositions. By means of the chemical corrosion of the glass phases, LSA glass-ceramics are effectively degraded in the citric acid solution. Then, the influence of B 2 O 3 and rare-earth (RE) on the structures of glass phases, the degradation of LSA glass-ceramics in the citric-acid solutions, and the dielectric properties are investigated systematically. The results suggest that when the B 2 O 3 molar ratio in the composition CaO–Al 2 O 3 –SiO 2 –B 2 O 3 is 0.5, doping LSA glass-ceramics with RE can reduce the quantity of bridging oxygen and [BO 4 ] units in the glass phase, as well as the degree of network connection of [AlO 4 ] units in the glass network. Conversely, when the B 2 O 3 molar ratio is decreased down to 0.3, doping RE into LSA glass-ceramics increases the quantity of bridging oxygen and [BO 4 ] units for glass phase. This improvement in chemical stability effectively impedes the degradation of LSA glass-ceramics in citric-acid solutions. Concurrently, the degradation mechanism of LSA glass-ceramics in citric acid solution is analyzed and explained in terms of classical glass corrosion theory, while the microstructural characteristics of LSA glass-ceramics are utilized to investigate their dielectric properties. It indicates that the dielectric loss and dielectric constant of LSA glass-ceramics are significantly lowered as a result of the existence of the glass phase. Especially when the B 2 O 3 molar ratio in the composition CaO–Al 2 O 3 –SiO 2 –B 2 O 3 is 0.3, and the La 2 O 3 doping percentage into LSA glass-ceramics is 0.5 wt%, the LSA glass-ceramics exhibit the lowest dielectric loss value of 3.13 × 10−3 and ε r = 4.17. Developing the LSA glass-ceramic with degradation in organic acids can provide a new idea for the recycling and disposal of e-waste. [ABSTRACT FROM AUTHOR]

In order to expand the photoresponsive spectrum of TiO 2 and improve its catalytic activity under visible light, the hollow urchin-like composites of TiO 2 @g-C 3 N 4 /GQDs (TCN/GQDs) with a core-shell structure heterojunction was synthesized through a hydrothermal method and calcination. Potassium titanium oxalate, melamine, and citric acid were utilized as the raw materials for this synthesis process. The TCN/GQDs composites were subjected to a range of analyses to examine their microstructure and photoelectric properties. The findings indicated that the synthesized composites effectively enhanced the absorption spectrum of TiO 2 in the visible light range by creating the stable heterojunctions among TiO 2 , g-C 3 N 4 and GQDs. Additionally, the ability of these composites to degrade toxic organic pollutants under visible light was studied by using several different organic dyes and antibiotics. The results demonstrated that the TCN/GQDs composites exhibited efficient visible light catalytic degradation capability on organic pollutants, and the degradation efficiency could approach to 100 % under visible light in a short time. Furthermore, the photocatalyst exhibited hardly change of degradation efficiency towards organic pollutants even after 5 cycles of testing, suggesting its commendable performance in visible light catalysis and potential for repeated utilization. [ABSTRACT FROM AUTHOR]

Sphagnum palustre L. is a Chinese herbal medicine with a long history, however, few studies have been performed on its chemical composition and active effects. In this study, we investigated the composition and antibacterial and antioxidant capacities of extracts obtained from Sphagnum palustre L. phytosomes extracted with conventional solvents (water, methanol, and ethanol) and two different hydrogen bond donors (citric acid and 1,2-propanediol) modified with choline chloride-type deep eutectic solvents (DESs). The results show that Sphagnum palustre extracts contained 253 compounds, including citric acid, ethyl maltol, and thymol. The highest total phenolic content (TPC) was obtained with a DES extraction method combining 1,2-propanediol and choline chloride (39.02 ± 7.08 mg gallic acid equivalent/g dried weight (DW). This shows the composition of Sphagnum palustre as a natural product and the application of DESs in the extraction of active ingredients, demonstrating the potential of peat moss extracts in cosmetics and health products. [ABSTRACT FROM AUTHOR]

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Aim: This study aimed to compare the effectiveness of initial irrigation with sodium hypochlorite (NaOCl) and final irrigation with QMix, 40% citric acid, and 17% ethylenediaminetetraacetic acid (EDTA) on smear layer removal and dentin erosion. Methodology: Forty extracted human mandibular premolar teeth were randomly divided into four groups (n = 10) according to the type of final irrigants used: 17% EDTA, QMix, citric acid, and control (normal saline). Canals were mechanically prepared using ProTaper Next instruments to an apical size of X3. Subsequently, the roots were sectioned in a buccolingual direction. Scanning electron microscopy (SEM) was used to assess the presence of the smear layer and the amount of dentin erosion in the coronal, middle, and apical thirds of the root canals. Results: In regards to smear layer removal, there was a significant difference between the control group and the other tested groups. Moreover, it was significantly higher in the coronal and middle thirds than in the apical third. However, there were no significant differences between the groups of EDTA, QMix, and citric acid. Concerning dentin erosion, citric acid produced significantly more dentin erosion than the other tested groups. Conclusion: Final irrigation with solutions had a higher ability to remove the smear layer in the coronal and middle thirds compared to the apical third. Of all the solutions tested, 40% citric acid had the most pronounced impact on dentin erosion, followed by 17% EDTA and QMix. [ABSTRACT FROM AUTHOR]

Agarose/micrometer titanium dioxide (TiO2) beads were essayed to test the photocatalytic capacity of two of the most widely prescribed drugs worldwide: paracetamol and ibuprofen. Although the initial tests demonstrated promising degradation rates for both drugs, the presence of turbidity, due to TiO2 leakage, during the photocatalytic essays induced to improve the stability of the photocatalytic composites. Among the different strategies adopted to strengthen such materials, crosslinking with citric acid and the use of alternative gelling agents: gellan, agargel™, and agar were chosen. Composites obtained by merging both strategies were characterized and employed to degrade both drugs under a simulated light that mimics the solar spectrum (indoor). Considering the superior degradation rates obtained when agar and agarose were used to shape the titanium oxide particles (up to 70–75% of drug destruction), such composites were subjected to a more realistic experiment (outdoor): solar illumination, tap water, and higher volumes, that should facilitate its ulterior scale up as a real wastewater depollution procedure. Degradation rates between 80 and 90% are attained under such conditions for both drugs. [ABSTRACT FROM AUTHOR]

Glyceric acid (GA), a carboxylic group-containing diol, is obtained from bioresources via microbial processes. In this study, we aimed to develop a reactive extraction method to separate GA from aqueous solutions using 2-naphthaleneboronic acid (2NB) and tri-octyl methyl ammonium chloride (TOMAC). Different feed molar amounts of 2NB (0–25 µmol), TOMAC (0–500 µmol), and NaOH (0–250 µmol) were used for GA (2.5 µmol) separation. A combination of 25 µmol 2NB, 100 µmol TOMAC, and 25 µmol NaOH was determined to be optimal for GA separation, providing 66.8 ± 3.2% GA yield at pH 11. GA was extracted by 2NB and TOMAC in a coordinated manner. Moreover, effects of various carboxylic acids (acetic, lactic, succinic, malic, tartaric, and citric acids) on GA separation from aqueous solutions were investigated. Interestingly, no significant effect on GA yeild (60.3 ± 1.2–65.2 ± 2.5%) was observed regardless of the type of carboxylic acid. The optimized protocol was subsequently applied to separate GA from crude GA solution prepared by incubating glycerol with the cells of the acetic acid bacterium, Acetobacter tropicalis NBRC 16470. GA separation was achieved at a comparable level (yield: 70.6 ± 4.6% and purity: 76.1 ± 4.1%) as that achieved using a GA reagent. This study demonstrated the efficiency of the repeated use of the organic phase for GA separation, with no significant changes in GA yield. [ABSTRACT FROM AUTHOR]

This work aims at investigating the effect of two eco‐friendly chemical treatments of Agave Americana fibers (AAFs) on morphology and mechanical properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx) biocomposites prepared by melt compounding. Acid citric and sodium bicarbonate treatments are used separately to modify the fiber surface before their incorporation into PHBHHx matrix at 30 wt%. The study reveals through SEM observations that the fracture surface of untreated PHBHHx biocomposite shows a poor fiber‐matrix adhesion with the presence of many microvoids at interface and also some fibers pullout. However, less surface defects with a finer morphology are observed on the treated biocomposite samples resulting in improved tensile and flexural properties compared with neat polymer, being however, more pronounced for those modified with sodium bicarbonate. The study highlights the beneficial effect of the green treatments investigated to enhance the mechanical properties of PHBHHx biocomposites. [ABSTRACT FROM AUTHOR]

Chemical treatments are used to remove hydrophilic OH groups and surface particles from the fiber surface for increasing aspect ratio of fibers and subsequently, mechanical properties. In this paper, the effect of two eco‐friendly chemical treatments on morphology, chemical structure, and thermal stability of Agave Americana fibers (AAFs) is investigated. The first chemical treatment of AAF is based on citric acid (C6H8O7) to substitute OH groups contained in AAF by ester groups, while the second one involves sodium bicarbonate (NaHCO3) to remove the lignin and hemicellulose components with the aim to promote good fiber‐matrix adhesion. Attenuated total reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR) data shows that both treatments are efficient to remove hemicelluloses and a part of lignin contained in AAF resulting in a rough and clean fiber surface. Thermal stability of AAF has clearly increased by NaHCO3 treatment compared to untreated one, unlike C6H8O7, which reduces this property. The study highlights the possibility of substituting conventional polluting chemical treatments with environmentally friendly ones to modify the surface of plant fibers for polymer composites reinforcement. [ABSTRACT FROM AUTHOR]

Achieving the clean utilization of coal is the priority of the coal industries. This paper proposed an efficient electrochemical technology for coal desulfurization before combustion. It was explored that citric acid can chemically provide enough acidic conditions for desulfurization reactions, and the ultrasonic-enhanced treatment physically helps to remove sulfur from coal due to its cavitation effect and mechanical effect. So the experiments of ultrasound-assisted electrochemical desulfurization using citric acid as the electrolyte solution were conducted. They combined physical and chemical methods to effectively remove sulfur from coal. The optimal operating parameters of the desulfurization effect were achieved by qualitative and quantitative analysis of coal samples(coal slurry concentration of 66 g/L, electrolysis time of 8 h, electrolyte concentration of 1.5 mol/L, electrolysis voltage of 4 V, electrolysis temperature of 30°C, ultrasonic strengthening time of 1 h and ultrasonic intensity of 320 W.). The total sulfur removal efficiency reached 45.09%. The electrolytic desulfurization experiments removed samples' sulfur contents, ash contents, and water. The crystal structures of gypsum, white iron ore, zinc sulfide, and the molybdenite mineral composition were also destroyed for purification. Gaussian simulations showed that C-S bonds and S-S bonds contained in non-thiophene organic sulfur are easier to remove, and S-S bonds are more likely to break than C-S bonds. This study realized the promotion of desulfurization with the ultrasonic wave and citric acid solution. It provides a new idea of synergistic desulfurization and is beneficial to reduce atmospheric sulfur pollution. [ABSTRACT FROM AUTHOR]

This study focused on synthesizing a cellulose-based hydrogel nanocomposite as a green hydrogel by adding a microcrystalline cellulose (MC) solution to carboxymethyl cellulose sodium (CMC-Na) with citric acid as a cross-linker. Y2O3 nanoparticles were incorporated during hydrogel preparation in different ratios (0.00% (0 mmol), 0.03% (0.017 mmol), 0.07% (0.04 mmol) and 0.10% (0.44 mmol)). FTIR analysis confirmed the cross-linking reaction, while XRD analysis revealed the hydrogels' amorphous nature and identified sodium citrate crystals formed from the reaction between citric acid and CMC-Na. The swelling test in deionized water (pH 6.5) at 25 °C showed a maximum swelling percentage of 150% after 24 h in the highest nanoparticle ratio. The resulting cellulose hydrogels were flexible and exhibited significant antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The synthesized cellulose-based hydrogel nanocomposites are eco-friendly and suitable for medical applications. [ABSTRACT FROM AUTHOR]

Waste from non-degradable packaging materials poses a serious environmental risk and has led to interest in developing sustainable bio-based packaging materials. Sustainable packaging materials have been made from diverse naturally derived materials such as bamboo, sugarcane, and corn starch. In this study, we made a sustainable packaging film using chitosan extracted from the biomass of yellow mealworm (Tenebrio molitor) shell waste. The extracted chitosan was used to create films, cross-linked with citric acid (CA) and with the addition of glycerol to impart flexibility, using the solvent casting method. The successful cross-linking was evaluated using Fourier-Transform Infrared (FTIR) analysis. The CA cross-linked mealworm chitosan (CAMC) films exhibited improved water resistance with moisture content reduced from 19.9 to 14.5%. Improved barrier properties were also noted, with a 28.7% and 10.2% decrease in vapor permeability and vapor transmission rate, respectively. Bananas were selected for food preservation, and significant changes were observed over a duration of 10 days. Compared to the control sample, bananas packaged in CAMC pouches exhibited a lesser loss in weight because of excellent barrier properties against water vapor. Moreover, the quality and texture of bananas packaged in CAMC pouch remained intact over the duration of the experiment. This indicates that adding citric acid and glycerol to the chitosan structure holds promise for effective food wrapping and contributes to the enhancement of banana shelf life. Through this study, we concluded that chitosan film derived from mealworm biomass has potential as a valuable resource for sustainable packaging solutions, promoting the adoption of environmentally friendly practices in the food industry. [ABSTRACT FROM AUTHOR]

As an innovative bio‐dairy product, yoghurt was enriched with Spirulina‐encapsulated aqueous/hydroalcoholic extracts of pomegranate peel (PP). Some metabolomics, antioxidative, textural and colour properties of bio‐yoghurt samples were investigated. The samples with Spirulina (YM) and PP (YPA) had the highest lactic, citric and uric acid. The aroma profile of the samples was affected encapsulation process and storage time. The values on day 1 and day 21 were 17.84–17.04 mg/kg for acetaldehyde, 0.98–0.90 mg/kg for diacetyl and 54.42–46.65 mg/kg for acetoin. The sample with encapsulated PP aqueous extract (YEPA) had the highest TPC (2.97 mg GAE/g), and the sample with PP aqueous extract (YPA) had the highest antioxidant capacity (0.36 mg TE/g). The present study describes that bio‐yoghurt enriched with Spirulina‐encapsulated PP could be considered a good alternative for consumers demanding functional dairy products and a holistic approach to a circular bioeconomy. [ABSTRACT FROM AUTHOR]

Electrokinetic remediation (EKR) has shown great potential for the remediation of in situ contaminated soils. For heavy metal-contaminated soft clay with high moisture content and low permeability, an electrokinetic remediation method with electrolytes placed above the ground surface is used to avoid issues such as electrolyte leakage and secondary contamination that may arise from directly injecting electrolytes into the soil. In this context, using this novel experimental device, a set of citric acid (CA)-enhanced EKR tests were conducted to investigate the optimal design parameters for Cu- and Zn-contaminated soft clay. The average removal rates of heavy metals Cu and Zn in these tests were in the range of 27.9–85.5% and 63.9–83.5%, respectively. The results indicate that the Zn removal was efficient. This was determined by the migration intensity of the electro-osmotic flow, particularly the volume reduction of the anolyte. The main factors affecting the Cu removal efficiency in sequence were the effective electric potential of the contaminated soft clay and the electrolyte concentration. Designing experimental parameters based on these parameters will help remove Cu and Zn. Moreover, the shear strength of the contaminated soil was improved; however, the degree of improvement was limited. Low-concentration CA can effectively control the contact resistance between the anode and soil, the contact resistance between the cathode and soil, and the soil resistance by increasing the amount of electrolyte and the contact area between the electrolyte and soil. [ABSTRACT FROM AUTHOR]

In recent years, the increasing demand and rising prices of rare earth elements (REEs), along with their attendant supply risk (about 95% of these elements are supplied by China), have led the European Commission to consider REEs as critical raw materials. Developing and optimizing processes for recovering REEs from secondary sources such as NdFeB magnets is fundamental in this context. A novel method to recover REEs by leaching with citric acid and subsequently separating these elements using the solvent extraction method has been introduced. Therefore, this research investigates the leaching efficiency of REEs, Fe, and B from NdFeB magnets. A full factorial design, with 18 experimental setups, was conducted to optimize the citric acid concentration (1–3 mol/L), leaching time (1–3 h), and solid–liquid ratio (5–10%wt./vol.). All tests were carried out at room temperature and 150 rpm. Different optimizations (response surface methodology (RSM) and artificial neural network (ANN) analysis) are used to maximize the REEs' leaching efficiency. RSM resulted in a maximum extraction yield of total rare earth elements (TREEs) of about 89% in the investigated experimental plan. This result is similar to that for ANN analysis (about 86%), but more accurate than that for RSM. In fact, for the ANN, an overall R-value higher than 0.99 was obtained. This result indicates that the developed ANN can be used as an accurate model for estimating the leaching efficiencies of REEs from NdFeB magnets. [ABSTRACT FROM AUTHOR]

Nowadays, transdermal drug delivery system (TDDS) has been developed continuously because it solves the problem of drug level inconsistencies in the blood and prevents the drug from being destroyed in the digestive tract. However, the limitations of TDDS are the low release rate of the patch and difficult penetration of the drug to the skin. Therefore, this research aims to study drug release behavior of aspirin with and without applied electrical potential for controlled drug release from the pullulan hydrogel patch using sodium trimetaphosphate and citric acid at various concentrations as the crosslinker. The pullulan hydrogel patches prepared by the solvent casting method were studied the release behavior by using a modified franz diffusion cell with containing pH 5.5 and 7.4 buffer solution at 37 ◦C for 2 h. The amount of drug release was compared with various electrical potentials as 0, 0.5, 1, 3, and 5 V. The aspirin release behavior from pullulan hydrogel was a Non-Fickian mechanism meaning that the aspirin was released via concentration gradient combined with swelling behavior of drug matrix. The amount of drug release and releasing rate was decreased with increasing the crosslinking ratio because of the lower the swelling behavior of matrix. In addition, the applied electrical stimulation enhanced the amount of drug release and releasing rate. The maximum release of aspirin is approximately 25% within 9 min from the hydrogel patch using sodium trimetaphosphate as a crosslinker and a 5 V which is higher than that of 0 V as 16% within 12 min. [ABSTRACT FROM AUTHOR]

In this study, the researchers evaluated the use of nano-zero-valent iron (nZVI) activated persulfate (PS) for the degradation of Rhodamine B (RhB). The effects of various operating parameters such as initial pH, and dosages of PS, nZVI and citric acid (CA) on the removal rate of RhB were investigated. The results demonstrated that at a PS dosage of 5 mmol·L-1, nZVI dosage of 0.3 g·L-1, 0.1 mmol·L-1 CA, and pH of 5, the degradation rate of RhB was 94.970%. The degradation and kinetic analysis of RhB using micron-scale zero-valent iron (mZVI) and nZVI revealed that nZVI exhibited higher activity with PS due to its smaller particle size. The activation of PS by nZVI is higher compared to mZVI, and the ineffective consumption is half that of the mZVI/PS system, the TOC removal rate increased by 18.65%. Kinetic analysis indicated that under the mentioned reaction conditions, the degradation process followed a pseudo-second-order reaction model, with the highest apparent reaction rate constant (kobs). The researchers also identified active radical species in the nZVI/PS system. Additionally, Gas Chromatography-Mass Spectrometry (GC-MS) analysis was used to detect reaction intermediates and propose a possible degradation pathway for RhB. [ABSTRACT FROM AUTHOR]

Wood, a fundamental material in construction, confronts durability and weathering challenges, notably UV-induced degradation leading to colour changes. This study investigated a novel treatment using citric acid and urea to enhance the UV stability of wood. The reaction between these compounds generates water-soluble fluorescent species and insoluble particles upon thermal treatment which may provide wood with UV protection. Specimens were treated with two different treatment methods and then exposed to 2016 h of accelerated weathering, during which colour was measured regularly. Citric acid and urea were either pressure impregnated into the wood and thermally reacted in situ during heat treatment or pre-reacted in the absence of wood with subsequent implementation into melamine formaldehyde (MF) and water-based surface coatings. The results showed that water-soluble fluorophore compounds were formed with both treatment methods. Accelerated weathering tests revealed significant colour changes over time, where specimens coated with a mixture of MF and fluorescent particles from the reaction between citric acid and urea, exhibiting the least alteration. The lowest colour change ΔE of 5.9 was observed for specimens coated with a MF-based coating containing 1 wt% of citric acid and urea thermally pre-reacted at a temperature of 180 °C, showcasing potential wood protection applications. [ABSTRACT FROM AUTHOR]

Citric acid can be used as a bio-based binding agent in composites made from lignocellulosic material due to its crosslinking ability with hydroxyl groups via ester formation. Even though plenty of research has investigated diverse manufacturing conditions, with a focus on citric acid content and pressing temperature, an apparent knowledge gap persists regarding their effect on the properties of particleboards made from softwood sawdust. Furthermore, the optimal temperature for particleboards crafted from mostly non-wood lignocellulosic materials was found to be 180–200°C which is lower than that observed for softwood material in a prior study. This study aimed to systematically examine the effects of citric acid content and pressing temperature on particleboards derived from softwood sawdust. Results highlighted a positive correlation of both citric acid content and pressing temperature with mechanical and hygroscopic properties of the particleboards, the best results being achieved at 20 wt% citric acid and 220°C, exhibiting a thickness swelling of 9%, internal bonding strength of 0.77 MPa and a modulus of rupture of 4.3 MPa. This study served as a foundational framework for future investigations into the addition of other chemicals, offering a comprehensive understanding of their interactions with citric acid in particleboard manufacturing. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants with carcinogenic, mutagenic and teratogenic effects. The white-rot fungi in the fungal group have significant degradation ability for high molecular weight organic pollutants. However, exogenous fungi are easily antagonized by indigenous microorganisms. Low molecular weight organic acids, a small molecular organic matter secreted by plants, can provide carbon sources for soil microorganisms. Combining organic acids with white rot fungi may improve the nutritional environment of fungi. In this study, immobilized Trametes versicolor was used to degrade benzo[a]pyrene in soil, and its effect on removing benzo[a]pyrene in soil mediated by different low molecular weight organic acids was investigated. The results showed that when the degradation was 35 days, the removal effect of the experimental group with citric acid was the best, reaching 43.7%. The degradation effect of Trametes versicolor on benzo[a]pyrene was further investigated in the liquid medium when citric acid was added, and the effects of citric acid on the biomass, extracellular protein concentration and laccase activity of Trametes versicolor were investigated by controlling different concentrations of citric acid. In general, citric acid can act as a carbon source for Trametes versicolor and promote its extracellular protein secretion and laccase activity, thereby accelerating the mineralization of benzo[a]pyrene by Trametes versicolor. Therefore, citric acid can be used as a biostimulant in the remediation of PAHs contaminated soil with Trametes versicolor. [ABSTRACT FROM AUTHOR]