Ion Concentration Research Articles

Tracking the electrocatalytic activity of Au@Ag core–shell nanoparticles for nitrite oxidation via single-entity electrochemistry

Single-entity electrochemistry (SEE) has been extensively utilized for analyzing various substances, elucidating their mechanisms, and predicting particle behavior on electrode surfaces. In this paper, we propose a novel method for analyzing the electrochemical reactions between core–shell nanoparticles (NPs) and nitrite ions at the single-particle level. This method employs single Au@Ag core–shell NPs, nitrite ions (NO2-), and a carbon ultramicroelectrode (C-UME), utilizing the electrochemical oxidation of NO2- ions upon collision with individual core–shell nanoparticles on the C-UME surface. Au@Ag core–shell NPs with different ratios were synthesized to achieve the effective oxidation of NO2- ions, and their electrochemical properties were analyzed. Various parameters, such as applied potential and NO2- ion concentration, were adjusted in chronoamperometric experiments to analyze the resulting signals. This study is expected to significantly contribute to the analysis of oxidation/reduction, dispersion, and catalytic properties of various NPs, particularly core–shell NPs.

A simulated sunlight-activated plastic mimic enzyme for dual-mode detection of D-penicillamine and serum iron

No reports disclosed that whether the plastic centrifuge tube with intrinsic photoenzyme activity can be used for the specific sensing of pharmaceuticals and biomarkers in biofluids so far. We herein report the plastic eppendorf (EP) tube as both reaction vessel and sunlight-activated plastic mimic enzyme for colorimetric/smartphone dual-mode detection of D-penicillamine (D-PA) and iron (Ⅲ) ions in goat and rabbit serums accordingly. The photooxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) combined with simulated sunlight-activated EP tube was selectively inhibited by adding D-PA, and the absorbance at 652 nm of oxidized TMB decreased. Good linearity between the absorbance variation (or R/(R + G + B)) and D-PA level ranging from 10 to 300 µM was obtained, and the limits of detection (LOD) were determined as 8.50 μM (colorimetric) and 6.92μM (smartphone). Furthermore, the polyvinyl alcohol hydrogel encapsulated TMB in EP tube as a smartphone biosensor had been triumphantly used to monitor D-PA level in goat serum. Interestingly, the adsorption band of photo-oxidized EP tube-TMB system inhibited by D-PA gradually increased as the enhancement of iron (Ⅲ) ions concentration. Based on the “on–off-on” effect, a sensitive and selective method was further used for selectively sensing iron (Ⅲ) in rabbit serum. Notably, the dual-mode sensing platforms exhibited outstanding detection performance, with LOD values as low as 0.50 µM and 0.65 µM respectively. In short, this work not only excavated a photoactivated-plastic mimics, but also developed a robust, low-cost, simple and sensitive biosensor for simultaneous detection of D-PA and Fe (Ⅲ) ions in biofluids. The current photoactivated sensor does not requires the introduction of exogenous catalyst except for simulated sunlight, plastic tube and chromogenic substrate.

Spatio-temporal distribution of Pb 2 + ion Concentrations along the Lom River (Adamawa Cameroon) from Gold Mining Sites

Spatio-temporal distribution of Pb 2 + ion Concentrations along the Lom River (Adamawa Cameroon) from Gold Mining Sites

Identifying the pattern of shallow groundwater hydrochemistry and its driving factors in a typical estuarine delta of Poyang Lake watershed, China: Insights into water quality assessment

Study regionA typical estuarine delta of Gan−Xiu River within Poyang Lake watershed, situated in the north of Jiangxi Province, China Study focusAlthough groundwater is considered as a crucial water resource for social development and public health, it presents significant challenges in preventing the deterioration of groundwater quality in the seasonal floodplain regions. Hence, this study focuses on the spatiotemporal variations of ionic concentrations of shallow groundwater in an estuarine delta of Gan-Xiu River in Poyang Lake watershed, which is greatly complicated by complex hydrological regimes and intensive anthropogenic activities such as cropland fertilizer. The potential factors controlling the ionic concentrations were identified using self-organizing map clustering and Piper diagram approaches. Moreover, the overall water quality of shallow groundwater was assessed according to the ionic compositions. New hydrological insights for the region(1) Shallow groundwater chemistry was influenced by weathering silicate and carbonate from ionic and Gibbs plots, which is highly associated with the distribution of the carbonate rock fissure-karst aquifer in the study region. (2) The contribution of groundwater to river water varied from 53.2% to 71.5% via isotopic analysis, suggesting that groundwater dominate the component of river water. (3) Most samples from cluster types are suitable for drinking and irrigation use except for sites from Cluster 6, which were characterized by the higher concentrations of Cl−, NO3− and SO42−.

Structure-guided inhibitor design targeting CntL provides the first chemical validation of the staphylopine metallophore system in bacterial metal acquisition

To survive in the metal-scarce environment within the host, pathogens synthesize various small molecular metallophores to facilitate the acquisition of transition metals. The cobalt and nickel transporter (Cnt) system synthesizes and transports staphylopine, a nicotianamine-like metallophore, and serves as a primary transition metal uptake system in Gram-positive bacteria including the human pathogen Staphylococcus aureus. In this study, we report the design of the first inhibitor of the Cnt system by targeting the key aminobutanoyltransferase CntL which is involved in the biosynthesis of staphylopine. Through structure-guided fragment linking and optimization, a class of acceptor-adenosine dual-site inhibitors against S. aureus CntL (SaCntL) were designed and synthesized. The most potent inhibitor, compound 9, demonstrated a ΔTm value of 9.4 °C, a Kd value of 0.021 ± 0.004 μM, and an IC50 value of 0.06 μM against SaCntL. The detailed mechanism by which compound 9 inhibits SaCntL has been elucidated through a high-resolution co-crystal structure. Treatment with compound 9 resulted in a moderate downregulation of intracellular concentrations of iron, nickel, and cobalt ions in the S. aureus cells cultured in the metal-scarce medium, providing the first chemical validation of the important role of Cnt system in bacterial metal acquisition. Our findings pave the way for the development of CntL-based antibacterial agents in future.

Improving efficiency and circularity of selective metals recovery from acid mine drainage

The mining sector in Europe is considered one of the main pillars of the economy. However, the mining activities generate a large volume of acid mine drainage containing dissolved metals, some of them with economic impact. In addition, the increasing global water scarcity makes it imperative to evaluate industrial wastewater as an alternative source for water reclamation. A treatment system based on reverse osmosis for metals concentration and water reclamation, followed by chemical precipitation for selective metals recovery, and electrodialysis with bipolar membranes for NaOH recovery and reuse is suggested in this work. The main objective is to improve the efficiency and circularity of precipitation processes by overcoming some of its main limitations, namely metal ions concentration and reagent consumption. The treatment system yielded promising results as 97% of the water was recovered as reclaimed water, targeted metals (Al, Zn, Cu, Mn, Mg, and Ca) were selectively recovered at rates greater than 60%, and up to 58% of NaOH was recovered, potentially reusable in the precipitation process.

Assessment of groundwater quality for agricultural purposes in Qazvin Province, northwestern Iran: A fuzzy inference and indicator Kriging approach

This study addresses the challenge of assessing groundwater quality for agriculture in Qazvin Province, northwestern Iran. In this region, over-extraction has led to significant degradation of groundwater resources. Traditional assessment methods often overlook uncertainties and spatial variability in groundwater quality. To address this, our study aimed to integrate fuzzy inference and geostatistical methods to assess groundwater quality under uncertain conditions. The research was conducted in two stages. First, a fuzzy inference system classified six key water quality parameters: Electrical Conductivity (EC), Sodium Adsorption Ratio (SAR), Residual Sodium Carbonate (RSC), Total Hardness (TH), sodium ion concentration (Na⁺), and chloride concentration (Cl⁻), into three categories: "desirable," "acceptable," and "unacceptable," using 54 fuzzy rules. In the second stage, we applied ordinary Kriging and indicator Kriging to spatially interpolate these classifications and produce probabilistic maps of groundwater quality risk across the study area. In ordinary Kriging, the average Root Mean Square Error (RMSE) values for EC, SAR, RSC, TH, Na⁺, and Cl⁻ were 0.94 dS/m, 1.54, 1.42 meq/L, 3.13 mg/L, 3.03 mg/L, and 2.62 mg/L, respectively, indicating reliable assessments of groundwater quality parameters. Results also suggest that by 2023, areas classified as "unacceptable" increased by 142.0% since 2009, with an additional 25.2% of the region facing a 40 to 80% probability of further degradation. These findings highlight important trends in groundwater quality, assisting local authorities in prioritizing areas for preventive interventions. This supports sustainable agricultural practices and aligns with the United Nations Sustainable Development Goal 6 for water resource management.

Bioinformatic Analysis of Neuropeptide Related Genes in Patients Diagnosed with Invasive Breast Carcinoma

PurposeNeuropeptide receptors are expressed in many malignancies. Effectors involved in the action mechanisms of HCRTR1, HCRTR2, NPY4R (PPYR1) may be related to breast cancer (BC). Genes encoding these receptors and PPY and PTPN11 genes were aimed to examine via bioinformatics tools in the BRCA cohort. To our knowledge, this is the first study in which these receptor genes and PP, which have not found much research in BC, are examined together with PTPN11 and analyzed comprehensively in large patient cohorts from public databases. MethodscBioPortal was used for gene alteration analyses, GeneMania for association analyses with other genes, Kaplan-Meier Plotter for Overall Survival (OS) and Relapse Free Survival (RFS) analyses, UALCAN for methylation analyses, TIMER2.0 for expression analyses, The Human Protein Atlas database for expression validations, TIMER for immune infiltration analyses, WEKA 3.8.6 for diagnostic classification performances of the genes based on Random Forest Classifier and Enrichr-KG for Gene Ontology (GO) Biological Process (BP) and KEGG analysis. Results19 (1.9%) nucleotide changes were found in 996 cases. Missense mutation is most common. Decreased expression levels of the HCRTR1 gene were associated with shorter OS and RFS, but decreased expression levels of the PTPN11 gene were associated with longer OS and RFS. Decreased expression levels NPY4R (PPYR1) gene were associated with shorter RFS. Increased expression levels of HCRTR2 and PPY genes were associated with longer RFS. HCRTR1 and NPY4R (PPYR1) genes were statistically hypermethylated; conversely HCRTR2 and PPY genes were hypomethylated. There was no significant change in PTPN11 gene promoter methylation level. HCRTR1, NPY4R (PPYR1) and PTPN11 gene expressions were downregulated; conversely, HCRTR2 and PPY gene expressions upregulated. Weak correlations were observed between NPY4R (PPYR1) gene expression and CD4+ T Cell, Neutrophil, Dendritic Cell and between PTPN11 gene expression and CD8+ T Cell, Macrophage, Neutrophil, Dendritic Cell infiltrations. Area under the receiver operating characteristics curve values of the 10-fold cross-validation and by splitting the dataset in a ratio of 80:20 models were 0.930 and 0.963 respectively. HCRTR2 and HCRTR1 belong to regulation of cytosolic calcium ion concentration, cellular calcium ion homeostasis GO BPs. ConclusionIn BC patients, increases in HCRTR2 and PPY gene expressions could be considered as positive prognostic factors. Decreases in HCRTR1 and NPY4R (PPYR1) gene expressions could be considered as negative prognostic factors. Decreased expression of PTPN11 gene may have a positive prognostic factor. Changes in existing genes are likely to be both a biomarker and therapeutic target for BC. However, experimental and clinical studies are needed to elucidate the mechanisms underlying these neuropeptide receptors in terms of breast carcinogenesis.

Preparation, characterization, stability, and antioxidant of quercetin-loaded hyaluronic acid complexes via pH-induced co-assembly

The purpose of this study was to investigate the feasibility of constructing an oral delivery system for quercetin (QUT) using hyaluronic acid (HA) as the wall material. The findings revealed that when the mass ratio of QUT to HA was 1:10, the prepared QUT-HA complexes exhibited excellent stability (particle size of 802 nm, zeta potential of -36 mV) and QUT loading capacity (encapsulation efficiency of 79.77%, loading capacity of 89.65 mg/g). The characterization of QUT-HA complex confirmed the formation of hydrogen bond between QUT and HA, resulting in a homogeneously dispersed coral-like complex and leading to the transformation of QUT's crystal structure into an amorphous state. Environmental stability analysis demonstrated that the QUT-HA complex maintains good stability within an ionic concentration range of 0-500 mM, a pH range of 3-8, and at temperatures of 50-90°C. In vitro simulations of gastrointestinal digestion indicated that the QUT-HA complex aggregates during simulated gastric fluid digestion and dissociates following simulated intestinal fluid digestion, effectively enhancing the bioaccessibility of QUT. Antioxidant assays showed that the scavenging ability of QUT against DPPH and ABTS radicals was significantly improved by complex loading. Therefore, the QUT-HA complex developed in this study possesses a high QUT loading capacity, excellent processing and digestive stability, and can effectively enhance the bioaccessibility and antioxidant activity of QUT, making it a promising candidate for use as an oral nutritional supplement in the field of functional foods.

Biotechnology of groundwater purification for water supply systems, using Gallionella and Lepthothrix ferrobacteria

Aim. The aim of the study was to consider the possibility of using the consortia of chemolithoautotrophic ferrobacteria from Gallionella genus and heterotrophic bacteria from Lepthothrix genus for the biological method of groundwater purification. Methods. The photocolorimetric method to determine the concentrations of ammonium and iron ions, the titrimetric method to determine the hydrocarbon and total alkalinity, the method of determining the permanganate oxidizability using the Kubel method, the potentiometric method to determine the values of рН and Еh, the electronic microscopy using the X-ray spectral analysis of matrix structures of bio-minerals, microbiological and statistical methods. Results. The main technological parameters of the water deironing process were defined as follows: the filtration velocity of the bioreactor – 7–11 m/h, and of the filters – 3.5–5 m/h; the filter-cycle duration – 48 h. It was found that the application of the two-stage technology of biological deironing in the bioreactor and filters provided for the possible removal of Fe2+ compounds up to 5.0 mg/cdm, ammonium nitrogen — up to 1.5 mg/cdm, soluble organic substances by PO – up to 6.0 mg O2/cdm. It was determined that the optimal parameters for the process of biological purification of neutral groundwaters, containing increased concentrations of Fe2+ cations were as follows: рН 7.0–7.2; hydrocarbon alkalinity 2.5–2.2 mmol/cdm; content of soluble oxygen – 1.5–2.0 mg/cdm. The ability of concentrated (Dos 200 mg/cdm) matrix structures of Gallionella and Lepthothrix ferrobacteria to remove Cr6+ ions from natural groundwaters was determined. The study found no considerable differences in the efficiency of applying disinfectants, produced using polyhexamethylene guanidine chloride (PHMGchl) or polyhexamethylene biguanidine chloride (PHMBchl). In concentrations of 0.25–0.5 %, they effectively disinfect pathogenic microorganisms, including Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The same was found true for the bacteria, most common in the systems of technical reverse water supply, the systems of water circulation, plant watering, and fire tanks, including Aeromonas hydrophila, Aeromonas salmonicida, Pseudomonas sp., E. coli, Flavobacterium columnare, Micrococcus lysodeikticus. Conclusions. This was the first study on the possibility of applying the biotechnology of groundwater purification from excessive amounts of iron in conditions of uneven hydraulic burden, notable for the water supply systems of rural areas and most agricultural enterprises in the north-western and northern regions of Ukraine. The specificities and perspectives of PHMGchl application in the systems of water preparation were studied. It was found that from the standpoint of safety and efficiency, the use of the water deironing processes involving iron bacteria was reasonable in the systems of water consumption and technical water supply, and the disinfection of water using PHMG was possible only in the second case, due to some toxicity of the preparation. The optimal parameters for the process of biological purification of neutral groundwaters, containing increased concentrations of Fe2+ cations were determined.

Advancements in maize cultivation: synergistic effects of dry atmospheric plasma combined with plasma-activated water

Abstract In this study, we investigate the effects of pre-germinative and post-germinative plasma treatments, applied separately or in combination, to improve maize germination and early seedling development. Pre-germinative treatment consists of priming the seeds with a dry atmospheric plasma (DAP) generated by a dielectric barrier device, characterized by minimal radiative emission, low electrical power (4 W) and high emissions of O, OH and NO radicals. Post-germinative treatment, known as plasma-activated water (PAW), uses a single pin electrode device (SPED) to generate a DC discharge that features a power of 126 W and produces large amounts of OH radicals. The resulting PAW, after 5 min of SPED treatment, induces a slight acidification and increased concentrations of nitrate ions (from 24 to 250 mg l−1), nitrite ions (from less than 0.1 to 56.1 mg l−1) and hydrogen peroxide (from 0.3 to 18.5 mg l−1). Results indicate that DAP applied on maize seeds for 20 min boosts their germination rate by up to 90% (versus only 65% for untreated seeds) while reducing the median germination time by 37.5%. Then, seedling growth monitoring is achieved on control, DAP, PAW and DAP + PAW groups to assess stem length, hypocotyl length, leaf count, collar diameter and fresh/dry mass. The DAP + PAW group shows the most robust growth, demonstrating a synergistic effect of the combined treatments, particularly with significantly longer stem lengths. Additionally, physiological analyses of seedling leaves indicate a decrease in chlorophyll content despite enhanced growth, while fluorescence microscopy reveals a reduction in stomatal density in leaves treated with DAP and PAW, especially in the combined treatment group, potentially impacting photosynthetic efficiency and water regulation.

Control system and process optimization for electroless nickel plating

A novel method based on mid-frequency vibration is proposed to eliminate coating defects such as bubbles during electroless nickel plating. An automated control system for the plating, enabling precise and stable measurements and adjustments of critical parameters such as plating solution temperature, pH, and nickel ion concentration, is also established, which significantly improves process efficiency and coating quality. Experimental results indicate that the system is capable of realizing stable operation over extended periods. A nonporous nickel–phosphorus coating with a thickness greater than 200 μm is successfully obtained, with high phosphorus content, robust adhesion, and superior machinability.

Condensable Particulate Matter Removal and Its Mechanism by Phase Change Technology During Wet Desulfurization Process

Limestone-gypsum wet flue gas desulfurization (WFGD) played a key role in SOx removal and clean emissions. However, it would also affect the condensable particulate matter (CPM) removal and compositions. The effects of the WFGD system on the removal of CPM and the contents of soluble ions in CPM were investigated in a spray desulfurization tower at varied conditions. The results indicate that the emission concentration of CPM decreased from 7.5 mg/Nm3 to 3.7 mg/Nm3 following the introduction of cold water spray and hot alkali droplet spray systems. This resulted in a CPM reduction rate of approximately 51%, reducing the percentage of CPM in total particulate matter and solving the problem of substandard particulate matter emission concentrations in some coal-fired power plants. The concentrations of NO3−, SO42−, and Cl− among the soluble ions decreased by 41–66.6%. As the liquid−to−gas ratio of the cold water spray and hot alkali droplet spray increased, CPM came into contact with more spray, which accelerated dissolution and chemical reactions. Consequently, the CPM emission concentration decreased by 17.4–19%. The liquid−to−gas ratio has a great effect on the ion concentrations of NO3−, SO42−, Cl− and NH4+, with a decrease of 28–66%. The temperatures of the cold water spray and the hot alkali droplet spray primarily affect the ionic concentrations of SO42− and Ca2+, leading to a decrease of 32.3–51%. When the SO2 concentration increased from 0 mg/Nm3 to 1500 mg/Nm3, large amounts of SO2 reacted with the desulfurization slurry to form new CPM and its precursors, the CPM emission concentration increased by 57–68.4%. This study addresses the issue of high Concentration of CPM emissions from coal-fired power plants in a straightforward and efficient manner, which is significant for enhancing the air quality and reducing hazy weather conditions. Also, it provides a theoretical basis and technical foundation for the efficient removal of CPM from actual coal-fired flue gas.

Experimental Study on the Chloride Ion Concentration of Cement Pastes Prepared with Limestone Powder

Experimental Study on the Chloride Ion Concentration of Cement Pastes Prepared with Limestone Powder

Efficiency of Reverse Osmosis Usage in Drinking Water Depots to Reduce Iron (Fe3+), Copper (Cu2+) and Zinc (Zn2+) Ion Levels

Research on the efficiency of reverse-osmosis drinking water depot to decreased levels of iron (Fe3+), Copper (Cu2+) and Zinc (Zn2+) ions have been done. The raw, the treated, and waste water are filtered using reverse osmosis (RO) three times a week. HNO3 then was added to the sample until it reached 15 mL. The determination of the concentration of the three ions was performed using atomic absorption spectrophotometer (AAS). The results showed a decrease of Fe3+ concentration of 73.21%, for Cu2+ decrease by 80.25%, while Zn2+ decrease by 82.08%. For waste water obtained iron ion concentration of 0.1794 mg/L, for Cu2+ by 0.0239 mg/L, while Zn2+ by 0.0962 mg/L.

The Donnan equilibrium is still valid in high-volume HDF.

Clinical studies have shown that hemodiafiltration reduces morbidity and mortality of dialysis patients compared to hemodialysis alone. This is attributed to its superior middle molecule clearance compared to standard hemodialysis. However, doubts arose as to whether a high convective flux through the dialyzer membrane has an influence on the equilibrium concentration of small ions, especially that of sodium. Due to the presence of negatively charged impermeable proteins on the blood side, the Gibbs-Donnan effect leads to an asymmetric distribution of membrane permeable ions on both sides of the membrane. In thermodynamic equilibrium, the concentrations of those ions can easily be calculated. However, the convective fluid flow leads to deviations from thermodynamic equilibrium. In this article, the effect of a convective flow on the ion distribution across a semipermeable membrane is analyzed in a theoretical model. Starting from the extended Nernst-Planck equation, including diffusive, convective, and electrostatic effects, a set of differential equations is derived. An approximate solution for flow speeds up to 0.1 ms-1 as well as a numerical solution are given. The results show that in any practical dialysis setting the convective flow has negligible influence on the electrolyte concentrations.

Optical characterization of molecular interaction strength in protein condensates.

Biomolecular condensates have been identified as a ubiquitous means of intracellular organization, exhibiting very diverse material properties. However, techniques to characterize these material properties and their underlying molecular interactions are scarce. Here, we introduce two optical techniques - Brillouin microscopy and quantitative phase imaging (QPI) - to address this scarcity. We establish Brillouin shift and linewidth as measures for average molecular interaction and dissipation strength, respectively, and we used QPI to obtain the protein concentration within the condensates. We monitored the response of condensates formed by FUS and by the low-complexity domain of hnRNPA1 (A1-LCD) to altering temperature and ion concentration. Conditions favoring phase separation increased Brillouin shift, linewidth, and protein concentration. In comparison to solidification by chemical crosslinking, the ion-dependent aging of FUS condensates had a small effect on the molecular interaction strength inside. Finally, we investigated how sequence variations of A1-LCD, that change the driving force for phase separation, alter the physical properties of the respective condensates. Our results provide a new experimental perspective on the material properties of protein condensates. Robust and quantitative experimental approaches such as the presented ones will be crucial for understanding how the physical properties of biological condensates determine their function and dysfunction.

Spatiotemporal distribution in chemical composition of wet atmospheric deposition in Bandung Indonesia.

Bandung, Indonesia, represents the complex interactions between climate variability, basin topography, and deposition processes. This study conducted a long-term spatiotemporal analysis, including pH distribution and pollutant accumulation monitoring, to observe the chemical composition of wet deposition in Bandung as part of the Acid Deposition Monitoring Network in East Asia (EANET). The results revealed that and were the predominant ions, followed by , with their distribution varying across different sites due to local emissions and atmospheric processes. The interactions between these ions, particularly the formation of secondary inorganic aerosols such as ammonium sulfate and ammonium nitrate, were closely linked to the basin's localized sources and topographical features. Areas experiencing high traffic congestion were classified as acidic regions due to their low pH levels. In contrast, a rural site exhibited a basic pH due to the high concentration of ion . Variations in pH and conductivity, along with the impacts of climatic events such as El Niño and La Niña, emphasized the role of weather patterns in shaping wet deposition dynamics. Seasonal trends indicated elevated total ion concentrations during the dry season, driven by sea salt contributions, as supported by strong correlations between Na+ and and between Na+ and Mg2+. Additionally, geological materials and atmospheric reactions contributed to the strong correlations observed between soil-derived cations and acidic species. The increasing trend in and the contrasting decrease in concentrations in rural areas suggest evolving emission sources and environmental conditions.

The Study of the Etching Resistance of YOF Coating Deposited by Atmospheric Plasma Spraying in HBr/O2 Plasma

Yttrium oxyfluoride (YOF) coatings with different oxygen content were prepared using atmospheric plasma spraying (APS) technology. The etching resistance of the coatings in HBr/O2 plasma was investigated. Shifts in diffraction peaks of the X-ray diffraction, along with XPS analysis conducted before and after etching, demonstrated that Br ions could replace O and F ions and fill the oxygen vacancies after exposure to HBr/O2 plasma, which is supported by the first-principles calculations. Br ions formed a protective layer on the surface of the YOF coating, slowing down further etching by Br ions. By adjusting the oxygen mass fraction in YOF powder, the oxygen vacancy concentration and Br ion filling were regulated to enhance etching resistance. YOF coatings with 6% oxygen content exhibited improved etching resistance compared to YOF coatings with 3% and 9% oxygen content. This improvement was primarily due to the increased Br ion concentration. These findings provide a new approach for developing coatings with enhanced etching resistance.

Synergistic mechanisms of humic acid and biomineralization in cadmium remediation using Lysinibacillus fusiformis.

Heavy metal pollution, particularly cadmium, poses severe environmental and health risks due to its high toxicity and mobility, necessitating effective remediation strategies. While both microbially induced carbonate precipitation (MICP) and humic acid adsorption are promising methods for heavy metal mitigation, their combined effects, particularly the influence of humic acid on the MICP process, have not been thoroughly investigated. This study explores the interaction between humic acid and MICP, revealing that humic acid significantly inhibits the MICP process by reducing urease activity, with the 10% humic acid treatment resulting in a 23.8% reduction in urease activity compared to the control. Additionally, while higher concentrations of humic acid did not significantly reduce cadmium ion concentrations, they did result in a slight increase in organically bound cadmium, indicating an interaction that could alter metal speciation in the soil. These findings provide important insights into the mechanisms by which humic acid affects MICP, offering a foundation for optimizing combined remediation approaches. Future research should aim to fine-tune the balance between MICP and humic acid to enhance the overall efficiency of cadmium remediation strategies. This study contributes to the development of more effective and sustainable methods for addressing cadmium contamination.