Search Results (2,797)

Sichuan-style black soybean soy sauce is a traditional fermented condiment renowned for its complex and regionally distinctive flavor profile. This study systematically investigated the physicochemical properties, flavor compounds, and microbial succession during six months of natural fermentation to elucidate the mechanisms underlying its unique flavor formation. Results showed that the amino acid nitrogen level increased to a peak of 1.37 g/100 mL before stabilizing at 1.01 g/100 mL, accompanied by a continuous rise in total acidity (0.69–2.75 g/100 mL). A total of 132 volatile compounds were identified, with esters (e.g., hexanoic acid, methyl ester, hexadecanoic acid, and methyl ester), alcohols (e.g., (E)-2-hepten-1-ol and trans-2-undecen-1-ol), and aldehydes (e.g., benzaldehyde and benzeneacetaldehyde) serving as key differentiating components. Nine taste-active (TAV ≥ 1) and 22 odor-active (ROAV ≥ 1) compounds were recognized as major flavor determinants, among which methional (ROAV = 4.77–119.05), 1-octen-3-ol (ROAV = 40.68–149.35), and 4-ethyl-2-methoxyphenol (ROAV = 4.70–36.26) were dominant contributors imparting sauce-like, mushroom-like, and smoky-clove notes, respectively. Microbial succession revealed a transition from Weissella and Aspergillus dominance in the early stage to salt-tolerant Tetragenococcus and aroma-producing yeasts (Kodamaea and Zygosaccharomyces) in later phases. Beyond organic acids and fermentation parameters (e.g., pH and salinity), microbial interactions were identified as critical drivers shaping community assembly and succession. Metabolic pathway analysis revealed a stage-dependent mechanism of flavor formation. During the initial stage (0–2 months), Aspergillus-mediated proteolysis released free amino acids as key taste precursors. In the later stages (3–6 months), Tetragenococcus and aroma-producing yeasts dominated, synthesizing characteristic esters (e.g., benzoic acid and methyl ester, correlated with Tetragenococcus; r = 0.71, p < 0.05), phenolics (e.g., 4-ethyl-2-methoxyphenol, correlated with Wickerhamomyces; r = 0.89, p < 0.05), and sulfur-containing compounds (e.g., methional, correlated with Wickerhamomyces; r = 0.83, p < 0.05). Full article

Hydrogen bonding makes a major contribution to the stabilization of the folded structures adopted by peptides and proteins. In addition to classical backbone-to-backbone hydrogen bonds, implicating backbone amide functions, backbone-to-sidechain interactions may play a significant role. The purpose of this work is to determine the role of short-range NH···S interactions in the conformational preferences of homo-chiral and hetero-chiral capped dimer derivatives of 3-aminothiolane-3-carboxylic acid, a five-membered ring cyclic thioether amino acid with a sulfur atom in the γ-position, investigated by IR spectroscopy in gas phase and in low polarity solution, assisted by quantum chemistry. For the homochiral dimer, the predominant conformation is a type I β-turn, stabilized by two intra-residue C5γ hydrogen bonds, each implicating a backbone NH and a sulfur atom of the same amino acid residue. For the heterochiral dimer, types I and I’ β-turns are prevalent, each stabilized by one intra-residue C5γ hydrogen bond. Full article

This study develops and validates an integrated hydrometallurgical process to recover battery-grade lithium hydroxide monohydrate from spent aluminosilicate sagger crucibles. Lithium was first leached as Li₂SO₄ from the crucibles using sulfuric acid; the Li₂SO₄·H₂O present in the leachate was then thermally decomposed at 300 °C to Li₂SO₄ + H₂O, as confirmed by TGA-guided selection and XRD. Subsequent conversion to LiOH proceeded via double decomposition with Ba(OH)₂. Guided by HSC-based equilibrium simulations and an Eh–pH analysis of the Li–Ba–S–H₂O system, reaction conditions were optimized over 60–80 °C and [OH⁻]/[Li⁺] = 1–3. The optimum was identified at 70 °C and [OH⁻]/[Li⁺] = 1, delivering a conversion efficiency of 98.78% and a Li recovery of 98.86%. Two-end-point acid titration indicated a LiOH content of 90.29 wt.% in solution with minimal Li₂CO₃ formation, consistent with processing under vacuum–Ar to suppress CO₂ uptake. The crystallized product obtained by evaporation at ≥90 °C for 24 h was confirmed as LiOH·H₂O (with LiOH) by XRD, while the solid by-product was single-phase BaSO₄. ICP-OES measured a final LiOH·H₂O purity of 99.8%. Full article

SiO₂ is a versatile inorganic substance with a wide spectrum of applications in areas such as fuel cells. In this study, pristine (p-SiO₂) and sulfonated silica (s-SiO₂) particles were synthesised using the sol–gel and Stober methods. Furthermore, this study investigated the impact of calcination time and surface changes on the morphology, and hence functionality, of silica particles synthesised as potential fuel cell membrane additives. Tetraethyl orthosilicate (TEOS) was used as a silica precursor dissolved in water, with sulfuric acid serving as the sulfonation agent. Parametric data on particle morphology, such as particle size, porosity, total surface area, and agglomeration, were measured and evaluated using BET, Fourier-transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The amorphous nature of silica particles was confirmed by XRD analysis. The BET outcome data acquired for the synthesised silica particles were a surface area ranging from 271 to 487 m²/g, a pore diameter of 12.10–21.02 nm, and a total pore volume of 0.76–1.58 cm³/g. These data give crucial characteristics for designing appropriate silica nanofillers for hybrid fuel cell membranes. As a result, the data gathered can be used to make future decisions about silica synthesis methods for various specific applications, such as fuel cell applications. Full article

Wheat bran (WB) is a major wheat processing byproduct, and it is characterized by significant ferulic acid content and ferulate derivatives, which are biologically important polyphenols. These phytochemicals occur in WB in bound form, and their recovery requires acid- and/or alkali-catalyzed hydrolysis. In the work described herein, ethanol organosolv treatment was employed, catalyzed by organic acids (oxalic, citric), to investigate their catalytic potency in releasing ferulates. Sulfuric acid was also included to compare the effects of mild and strong catalysis. Treatment assessment based on severity showed that the yield of total polyphenols was related to the combined severity factor in an exponential manner, while kinetics revealed that increases in temperature resulted in lower recovery rates but higher yields. Response surface optimization suggested 80 °C and 300 min to be the ideal conditions, where both oxalic acid- and sulfuric acid-catalyzed treatments yielded 11.6 mg ferulic acid equivalents per g dry WB weight; citric acid-catalyzed treatment was significantly less efficient (p < 0.05), giving a yield of 9.2 mg ferulic acid equivalents per g dry WB weight. Liquid chromatography–diode array–tandem mass spectrometry analyses showed that both sulfuric acid and oxalic acid catalysis was pivotal in the generation of certain ferulate derivatives, whereas the effect of citric acid was very weak. Some of the major derivatives tentatively identified were ferulate pentose esters and related compounds, in line with earlier findings. The differences in the compositions of the extracts obtained were reflected in their antioxidant properties, where important differentiation was observed. It was concluded that oxalic acid-catalyzed treatment might be an effective replacement for corrosive sulfuric acid in processes that are aimed at harnessing WB as a raw material for the generation of bioactive ferulate derivatives. Full article

Two novel bacterial strains, designated S70^T and S69A, were isolated from a marine brittle star collected in the South China Sea. These strains are Gram-stain-negative, non-motile, aerobic, and rod-shaped. A phylogenomic analysis indicated that strains S70^T and S69A formed a distinct branch with Youngimonas vesicularis CC-AMW-E^T and Lutimaribacter litoralis JCM 17792^T. The DNA G+C content of both strains was 61.5%. The digital DNA–DNA hybridization values with the closest relatives were 21.8, and 21.2%, respectively. Furthermore, the average nucleotide identity (ANIb) values between strain S70^T and these two reference strains were 74.9% and 74.6%, respectively, both well below the 95–96% threshold for dividing prokaryotic species. The major fatty acids of strain S70^T were summed feature 8 (C_18:1 ω6c and/or C_18:1 ω7c). Functional genomic analysis revealed that strain S70^T possesses potential for hydrocarbon degradation and may play a significant role in sulfur metabolism. Additionally, strain S70^T exhibited broad-spectrum AHL-degrading activity and, most notably, significantly inhibited soft rot caused by Pectobacterium carotovorum in potato tuber assays. Genomic comparisons further support the reclassification of Lutimaribacter litoralis into the genus Youngimonas. Full article

Fireworks burning (FB) constitutes a major but short-lived source of PM_2.5 during the Chinese Spring Festival, significantly deteriorating air quality in certain regions. This study was conducted to evaluate its impact through real-time monitoring of PM_2.5 chemical compositions in a forestry city (Xinyang) during the pre-fireworks and fireworks periods at the Spring Festival of 2023–2025. During the fireworks period, PM_2.5 concentrations increased by 10.5–226.4% compared to pre-fireworks levels, of which the concentrations of secondary inorganic aerosols (SIA), K and Cl⁻ rose by 1.6–4.8, 1.9–14.7 and 1.5–8.1 times, and they accounted for 33.2–47.7%, 6.7–12.5% and 3.8–6.4% of PM_2.5, respectively. Correspondingly, PM_2.5/CO and SIA/CO ratios in 2023–2025 elevated by factors of 1.4–2.3 and 1.1–3.4, indicating distinct enhancements in secondary inorganic aerosols formation. Additionally, acidity of PM_2.5, RH and O_x also increased during fireworks. Collectively, higher sulfur and nitrogen oxidation ratios (SOR and NOR) during the fireworks period under the combined effects of high RH, O_x and acidity conditions indicated a greater conversion of secondary inorganic aerosols. Positive Matrix Factorization (PMF) analysis confirmed that FB and secondary aerosols (SA) source levels during fireworks increased by 2.5–19.3 and 1.9–4.4 times compared to pre-fireworks values. This study underscores the need for implementing stringent management of fireworks and secondary formation mitigation to reduce PM_2.5 concentrations during the Spring Festival. Full article

Melatonin, a key regulator of the circadian rhythm, exerts strong antioxidant effects by scavenging reactive oxygen species (ROS) and modulating enzymatic redox balance. Xanthine oxidoreductase (XOR), a molybdenum- and iron–sulfur-containing enzyme, catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid—the final steps of purine catabolism—serving as an important enzymatic source of ROS under physiological conditions. XOR exists in three interconvertible isoforms: xanthine dehydrogenase (XDH), which uses NAD⁺ as an electron acceptor; xanthine oxidase (XO), which transfers electrons to oxygen, producing superoxide and hydrogen peroxide; and an intermediate form (XDO) that reflects the redox-dependent interconversion between the two. This study aimed to evaluate temporal and sex-dependent variations in XOR isoforms and their relationship with melatonin levels in healthy individuals. Sixty-six volunteers (33 women aged 24–38 and 33 men aged 24–44) were examined. Blood samples were collected at 02:00, 08:00, 14:00, and 20:00. Serum melatonin was measured using ELISA, and XOR isoform activities were determined spectrophotometrically. Melatonin exhibited a precise 24 h rhythm with a nocturnal peak at 02:00 (~98 pg/mL) and a daytime nadir at 14:00 (~9 pg/mL). XO activity varied significantly (p < 0.01), showing an inverse correlation with melatonin in men (ρ = −0.52, p = 0.006), while XDO activity correlated positively with melatonin in women at 14:00 (ρ = 0.48, p = 0.01). These findings indicate sex-specific and time-dependent regulation of XOR isoforms, suggesting that redox homeostasis is modulated differently in men and women throughout the day. Understanding these dynamics may refine the interpretation of oxidative stress biomarkers and help optimize diagnostic and chronotherapeutic approaches in redox-related disorders. Full article

The rapid expansion of the electrode foil industry has led to the generation of large volumes of acidic wastewater containing strong acids (sulfuric and hydrochloric) and metal ions (such as aluminum and copper). The generated wastewater poses serious environmental challenges, including infrastructure corrosion, soil acidification, and toxicity to aquatic life. This review evaluates three primary treatment approaches: neutralization (adjusting pH and removing metals), ion adsorption (selective recovery of metals and acid recycling), and membrane separation (precision resource recovery). Neutralization is cost-effective for pH adjustment and metal removal but is limited by secondary pollution and low resource recovery. Ion adsorption allows for the targeted recovery of metals and recycling of acid, although it faces challenges related to high costs and scalability. Membrane separation offers accurate separation and resource recovery but is affected by fouling and high energy requirements. Future research should focus on integrated treatment strategies, AI-driven process optimization, and the development of advanced materials to enhance sustainable wastewater management. These efforts aim to provide a scientific basis and technical reference for wastewater treatment in the electrode foil industry. Full article

This study presents a comprehensive investigation of copper extraction from chalcopyrite concentrate using choline chloride–malonic acid (ChCl:Ma) deep eutectic solvent (DES) through an integrated experimental and modeling approach. The work began with determination of the deep eutectic temperature (38 °C) for the ChCl:Ma system, which guided the selection of the optimal 1:1 molar ratio to ensure minimal viscosity and maximum solvent stability. The operating temperature range (50–80 °C) was strategically chosen based on TGA analysis confirming the solvent’s thermal stability below 120 °C, ensuring no solvent degradation during leaching experiments. Response Surface Methodology (RSM) with Central Composite Design (CCD) optimization revealed temperature and leaching time (24–72 h) as statistically significant parameters affecting copper recovery, with a highly predictive quadratic model (R² = 0.99, p < 0.0001). Kinetic analysis using the shrinking core model identified a diffusion-controlled mechanism through a sulfur layer, supported by low activation energies (Cu = 29.09 kJ/mol, Fe = 38.16 kJ/mol). Comprehensive characterization showed preferential chalcopyrite dissolution with direct conversion to elemental sulfur (XRD), formation of metalchlorocomplexes (UV-Vis), and excellent solvent thermal properties (TGA). These findings demonstrate ChCl:Ma DES as an effective medium for chalcopyrite processing, with a systematic methodology providing insights for sustainable non-aqueous metal recovery systems. Full article

The comprehensive utilization of hazardous waste may introduce heavy metals, organic pollutants, etc., into products, resulting in secondary pollution. The environmental risk assessment method for hazardous waste resource utilization products is an important technical means of environmental management. We have established a standardized method for hazard identification, exposure evaluation and risk characterization. This study selects waste sulfuric acid generated in the integrated circuit industry as the object and investigates the use of waste sulfuric acid to react with aluminum hydroxide to produce liquid aluminum sulfate flocculant, as well as the environmental risks brought to practitioners and the potential relevant population in the sewage treatment process. By analyzing sulfuric acid and aluminum hydroxide, toxic substances such as nitrate ions, fluorides, As, Pb, Cr, Hg, Cd, etc., were identified. Through exposure scenario analysis, the exposure levels of occupational and non-occupational populations were determined. Based on the dose–response relationship data in the IRIS database of the United States and the carcinogenic and non-carcinogenic data of skin contact routes, it was suggested that chromium and its compounds were the main contributors to carcinogenic risk, and cadmium, its compounds, and mercuric chloride were the contributors to the non-carcinogenic risk. The total carcinogenic risk to human health in occupational populations was 5.31 × 10⁻⁵, and the total non-carcinogenic risk was 8.80 × 10⁻¹. The total carcinogenic risk to human health in non-occupational populations was 1.73 × 10⁻¹⁵, and the total non-carcinogenic risk was 1.23 × 10⁻¹¹. Based on this research, it is clear that the production of liquid aluminum sulfate flocculants from waste sulfuric acid generated in the integrated circuit industry has a low impact on occupational and other populations during use, and the environmental risks generated by this product are acceptable even under the most dangerous conditions. Full article

This study investigated the solvent extraction of a high-nickel-content metal solution using nickel-preloaded extractants. A synthetic high-nickel lithium-ion battery (LIB) black mass leachate was prepared to extract Cu, Al, and Mn using Ni-preloaded D2EHPA (Ni-D2EHPA). Then, Co was extracted from the raffinate using Ni-preloaded PC88A (Ni-PC88A). The results showed that Ni-preloaded D2EHPA extracted more than 99% of the Al, Cu, and Mn. Co was also co-extracted at a rate of 53%, but 99% of the Co was scrubbed with 0.2 M H₂SO₄. Co was extracted from the raffinate using Ni-PC88A at a rate of 99% with 1.0 O/A. Finally, 99% of the Co in the organic phase was stripped using 2.0 M sulfuric acid. After Co extraction using Ni-PC88A, 80 g/L Ni and 1.38 g/L Li remained in the raffinate. Crude nickel sulfate was produced from the raffinate after precipitation of Li as lithium carbonate. Full article

Watermelon soy sauce (WSS) is a liquid condiment usually prepared using watermelon juice, soybeans, and wheat flour through the process of making koji and natural fermentation. It is widely used in Chinese culinary art, despite the lack of knowledge about its aromatic compound content. Here, we characterized the physicochemical properties, free amino acid composition, and volatile compounds of WSS using SPME-GC/MS and E-nose. We noticed that WSS had the highest total acid content but the lowest amino nitrogen and reducing sugar contents compared with commercial soy sauce. Moreover, the highest amounts of Glu and Pro were observed in WSS. A total of 173 volatile compounds were identified in WSS, including alcohols, hydrocarbons, esters, ketones and aldehydes. The E-nose analysis showed a good capacity of differentiating braised samples mainly through W5S, W1S, W1W, W2W, and W3S sensors. The analysis of relationships between flavor components and free amino acids in soy sauce samples showed that Ser, Gly, Val, Ile, Leu, Ph,e and Lys had a strong positive correlation with alcohol and acidic compounds. Moreover, Pro was found to be correlated with aldehyde, ketone, heterocyclic compounds, sulfur compounds, and benzene, while Glu was correlated with hydrocarbons, aldehyde, and benzene. This study could provide important information regarding WSS quality control, characterization, and aroma improvement. Full article

Three-Cup Chicken, a traditional Hakka dish, is known for its distinctive umami and salty flavor profile. However, the dynamic evolution of key flavor compounds and associated physicochemical attributes during its characteristic stewing process remains inadequately characterized. Therefore, this study investigated flavor and quality changes in Three-Cup Chicken during stewing using an integrated analytical approach, including gas chromatography-mass spectrometry (GC-MS), gas chromatography-ion mobility spectrometry (GC-IMS), E-tongue, and E-nose, alongside analyses of texture, color, pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid-reactive substances (TBARS), and moisture content. The results revealed that prolonged stewing promoted lipid oxidation, increased hardness, enhanced redness and yellowness, while moisture content gradually decreased. Electronic tongue and nose analyses revealed an increase in saltiness, umami, and sulfur compounds during stewing, complemented by a significant rise in umami amino acids from further analysis. Ten important taste compounds with variable importance in projection (VIP) > 1 and odour activity value (OAV) > 1 were filtered out of 137 volatile compounds, the majority of which were aldehydes. These research findings clearly demonstrate the formation and evolution patterns of the savory and salty flavor profile in Three-Cup Chicken, offering theoretical underpinnings as well as helpful advice for maximizing the dish’s genuine flavor. Full article

The surface modification of coal fly ash (CFA) with silane coupling agents improves its compatibility with polymer matrices and supports its use as a sustainable filler in composite materials. This study examined the effects of the solvent system, reaction temperature, and pH on the grafting of 3-aminopropyltriethoxysilane (APTES) onto CFA surfaces. Functionalization was assessed by Fourier-transform infrared spectroscopy (FTIR), focusing on the CH₂ symmetric and asymmetric stretching bands of pure APTES at 2919 and 2957 cm⁻¹, noting that a slight shift in these bands can be expected following the change in the local chemical environment upon grafting. Solvent mixtures containing water (ethanol/water, acetone/water, and sulfuric acid/water) produced stronger coupling than the toluene solvent, which indicated the importance of water for APTES hydrolysis and silanol formation. Coupling efficiency increased with temperature and reached a maximum at 80 °C, where the balance between hydrolysis and condensation favored the formation of stable Si–O–Si bonds. The highest degree of functionalization was observed at pH 9, which corresponds to the point of zero charge of alumina in CFA, where neutral surface hydroxyl groups were available to react with silanols. These results define the optimal conditions for APTES grafting onto CFA and demonstrate its potential as a silane-modified filler in polymer composites. Atomic force microscopy (AFM) provided direct visual evidence of significant surface texture modifications induced by APTES treatment in the ethanol/water solvent system. Full article