Search Results (81)

Background: Transition metal complexes incorporating fluorinated counter anions represent a significant class of compounds with broad applications in industry, pharmaceuticals, and biomedicine. These fluorinated anions are known to enhance the solubility, stability, and reactivity of the complexes, thereby expanding their functional utility in various chemical and biological contexts. Methods: A set of metal(II) complexes of the general formula [MPy₆][B(C₆F₅)₄]₂ where (Py = pyridine, M = Mn (1), Fe (2), Co (3), Ni (4), Cu (5), Zn (6)) have been synthesized by direct reaction of metal halides and pyridine in the presence of Ag[B(C₆F₅)₄]. The complexes were characterized using different techniques to assure their purity, such as elemental analysis (EA), electron paramagnetic resonance (EPR) spectroscopy, thermogravimetric analysis (TGA), ultraviolet–visible (UV–Vis) spectroscopy, ¹¹B-NMR, ¹H-NMR, and FT-IR spectroscopy. The antimicrobial and antifungal properties against different types of bacteria and fungi were studied for all prepared complexes. Results: The synthesized complexes exhibited broad-spectrum antimicrobial activity, demonstrating variable efficacy compared to the reference antibiotic, oxytetracycline (positive control). Notably, complex 6 displayed exceptional antibacterial activity against Streptococcus pyogenes, with a minimum inhibitory concentration (MIC) of 4 µg/mL, outperforming the control (MIC = 8 µg/mL). Complexes 1, 2, and 4 showed promising activity against Shigella flexneri, Klebsiella pneumoniae, and Streptococcus pyogenes, each with MIC values of 8 µg/mL. Conversely, the lowest activity (MIC = 512 µg/mL) was observed for complexes 3, 5, and 6 against Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae, respectively. Regarding antifungal properties, complexes 5 and 6 demonstrated the highest activity against Candida albicans, with MIC values of 8 µg/mL, equivalent to that of the positive control, fluconazole. Density functional theory (DFT) calculations confirmed an overall octahedral coordination geometry for all complexes, with tetragonal distortions identified in complexes 3, 4, and 5. Full article

C2H2 zinc finger (C2H2-ZF) transcription factors, characterized by the presence of a conserved ZnF-C2H2 domain, are widespread among plant-pathogenic fungi such as Magnaporthe oryzae, Fusarium graminearum, and Sclerotinia sclerotiorum and have critical roles in the regulation of fungal growth, development, stress adaptation, and secondary metabolism. However, little is known about the presence and roles of C2H2-ZF transcription factors in Setosphaeria turcica (syn. Exserohilum turcicum), the causal agent of northern corn leaf blight. To address this gap, we identified the complete set of C2H2-ZF transcription factors in the S. turcica genome and characterized their structural characteristics, physicochemical properties, and protein–protein interaction network. We then used RNA sequencing to profile their expression dynamics during fungal development and host infection. The 27 S. turcica C2H2-ZF proteins were classified into three major subfamilies and contained six conserved motifs. All 27 genes were transcribed during 5 stages of fungal development, and 24 were expressed during the infection of susceptible maize, suggesting that they function in both fungal growth and pathogenesis. This study represents the first systematic characterization of C2H2-ZF proteins in S. turcica, offering insight into their potential roles in pathogenicity and establishing a foundation for future functional studies of individual family members. Full article

Developing effective treatment technologies for heavy metal-contaminated biomass is of great environmental significance. This study explores the hydrothermal carbonization (HTC) of biomass contaminated with heavy metals (Cu, Zn, Cd, and Pb), focusing on the migration, transformation, and ecological stability of these metals during the process. Biomass samples were treated under subcritical conditions at varying temperatures (170–260 °C) and reaction times (1–4 h). Results showed that heavy metals were mainly enriched in biochar (>98%), and Cu predominantly transformed into metallic copper (Cu⁰), Zn tended to form stable organometallic complexes or remain in non-volatile forms, Pb coexisted in both metallic and carbonate species, and Cd converted into metallic and oxidized states. The transformation of these metals was influenced by reaction parameters, such as temperature and time, which affected both their immobilization and the structural properties of the prepared hydrochar. The Tessier extraction experiments showed that the unstable state (F1, F2) of heavy metals in hydrochar was obviously reduced from 17.9% to 6.8%, and the heavy metals were significantly stabilized compared with the original biomass. This research highlights the potential of HTC as a dual-purpose technology for biomass conversion and heavy metal remediation, offering insights for stabilizing contaminants and producing environmentally stable biochar products. Full article

We conducted a mechanistic and experimental study on zinc fluoride roasting for the recovery of NdFeB waste to address the difficulties faced during this pyrometallurgical recovery process, such as the high dependence on the quality of raw materials, the high energy consumption involved in roasting transformations, and the low added value of mixed rare earth products. Thermodynamic calculations showed the feasibility of fluorinating rare earths in NdFeB waste, and one-factor experiments were performed. The results showed that at a roasting temperature of 850 °C, a reaction time of 90 min, and 100% ZnF₂ addition, the fluorination rate of rare earths could reach 95.69%. In addition, after analyzing the mesophase composition of a clinker under different roasting temperature conditions, it was found that, when the roasting temperature exceeded 850 °C, the fluorination rate of rare earths was reduced, which was consistent with the thermodynamic results. On this basis, response surface methodology (RSM) was used to carry out experiments to investigate in depth the effects of various factors and their interactions on the fluorination rate of rare earths, which provides a sufficient experimental basis for the recovery of NdFeB waste via fluorination roasting. The results of this study show that ZnF₂ addition had the greatest influence on the rare earth fluorination reaction, followed by roasting temperature and roasting time. According to the optimization results of the model, the optimal roasting conditions were determined as follows: 119% ZnF₂ addition at 828 °C, a roasting time of 91 min, and a rare earth element fluorination rate of 97.29%. The purity of the mixed fluorinated rare earths was as high as 98.92% after leaching the roasted clinker with 9 M hydrochloric acid at a leaching temperature of 80 °C, a liquid–solid ratio of 4 mL/g, and a leaching time of 2.5 h. This study will lay the foundation for promoting the application of pyrometallurgical technology in the recycling of NdFeB waste. Full article

As some previously reported studies have proven that amodiaquine, in addition to its primary antimalarial activity, also has potential for new applications such as the inhibition of cholinesterases, in our study we focused on the evaluation of the influence of different substituents in the aminoquinoline part of the amodiaquine structure on the inhibition of human acetylcholinesterase and butyrylcholinesterase to investigate the possibility for their use as drugs for the treatment of AD. We synthesized a series of amodiaquine derivatives bearing H-, F-, CF₃-, NO₂-, CN-, CO₂H- or CH₃O- groups on the aminoquinoline ring, and determined that all of the tested derivatives were very potent inhibitors of both cholinesterases, with inhibition constants (K_i) in the nM and low μM range and with prominent selectivity (up to 300 times) for the inhibition of acetylcholinesterase. All compounds displayed an ability to chelate biometal ions Fe²⁺, Zn²⁺ and Cu²⁺ and an antioxidant power comparable to that of standard antioxidants. Most of the compounds were estimated to be able to cross the blood–brain barrier by passive transport and were nontoxic toward cells that represent the models of individual organs. Considering all these beneficial features, our study has singled out compound 5, the most potent AChE inhibitor with a CH₃O- on C(7) position, followed by 6 and 14, compounds without substituent or hydroxyl groups in the C(17) position, respectively, as the most promising compounds from the series which could be considered as potential multi-target drugs for the treatment of AD. Full article

Biotic ligand models (BLMs) predict the toxicity of metals in aquatic environments by accounting for metal interactions with cell surface receptors (biotic ligands) in organisms, including water chemistry (metal speciation) and competing cations. Metal binding constants (log K_MBL values), which indicate the affinity of metals for cell surface receptors, are fundamental to BLMs, but have only been reported for a few commonly investigated metals and freshwater species. This review evaluated literature toxicity and uptake data for seven key metals (cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), uranium (U), and zinc (Zn)) and four key competing cations (protons (H), calcium (Ca), magnesium (Mg), and sodium (Na)), to derive average metal binding constants for freshwater organisms/taxa. These constants will improve current BLMs for Cd, Cu, Ni, Pb, and Zn, and aid in developing new BLMs for Co and U. The derived metal binding constants accurately predicted metal toxicity for a wide range of freshwater organisms (75–88% of data were within a factor of two and 88–98% of data were within a factor of three of the ideal 1:1 agreement line), when considering metal speciation, competing cations and the fraction of cell receptors ((f_C)_M^50%) occupied by the metal at the median (50%) effect concentration (EC₅₀). For many organisms, toxicity occurs when 50% of cell surface receptors are occupied by the metal, though this threshold can vary. Some organisms exhibit toxicity with less than 50% receptor occupancy, while others with protective mechanisms show reduced toxicity, even with similar log K_MBL values. For Cu, U, and Pb, the toxic effect of the metal hydroxide (as MOH⁺) must be considered in addition to the free metal ion (M²⁺), as these metals hydrolyse in circumneutral freshwaters (pH 5.5 to 8.5), contributing to toxicity. Full article

Groundwater, a primary source of freshwater on Earth, is rapidly declining due to natural and anthropogenic activities. This study aimed to investigate the spatial distribution of dissolved organic matter (DOM) and heavy metals (HMs) in two municipal groundwater networks (A and B) from tube wells to taps in an industrial city, Faisalabad. The results showed that parameters such as color, turbidity, pH, EC, TDS, Ca²⁺, Mg²⁺, CO₃²⁻, HCO₃⁻, Cl⁻, CaCO₃, Na+, and NO₃⁻ were within the permissible limits set by the World Health Organization (WHO) and Pakistan Environmental Quality Standards (PEQSs). However, parameters like DO and COD exceeded standard values along the routes. Odor, taste, temperature, BOD, NH₄⁺, T. coli, and F. coli surpassed acceptable levels at the tap end of both networks. Fluorescence EEM-PARAFAC spectra were analyzed at an excitation wavelength of 220–500 nm and emission wavelength of 240–550 nm, revealing UVA-humic-like (C1–C2) and UVC-humic-like (C3) components in the DOM. Based on fluorescence intensity, DOM was dominated by C2 > C1 > C3 compounds in both networks. The mean concentrations of HMs, including Cu, Zn, and Fe, fell below the prescribed limits in both networks. However, concentrations of Pb (A: 0.015–0.028 mg/L), (B: 0.013–0.027 mg/L), and Cd (A: 0.004–0.006 mg/L), (B: 0.005–0.008 mg/L) exceeded permissible limits from tube wells to taps. Moreover, C1 demonstrated a significant positive correlation with Cd and Cu in networks A and B, respectively. Furthermore, C2 displayed a significant positive correlation with Cd in network A. This study concludes that the groundwater in both networks (A and B) is contaminated by agricultural runoff, industrial and sewage water, plumbing materials, and eroded pipelines. As a result, the water is unsafe for cooking and drinking, posing risks of kidney, lung, and bladder cancers. Therefore, this study urgently recommends pipeline reconstruction and the implementation of proper groundwater remediation approaches before these sources are used for drinking. Full article

Agricultural practices profoundly influence soil microbial populations and physicochemical properties, vital for crop growth and quality. This study aims to explore the impact of diverse agrochemical applications on soil microbial dynamics, physicochemical properties, and maize yield and proximate properties. Topsoil samples, collected at depths of 1 to 15 cm, were transported to Jimma University for maize cultivation. Over 120 days, soil and maize samples were collected at specified intervals for analysis, including soil pH, microbial populations, and nutrient content. Statistical analysis using one-way ANOVA (p < 0.05) was conducted. Soil bacterial and fungal populations were measured on days 5, 10, 20, 40, 80, and 120. The highest total mesophilic bacterial count (TMBC) was in compost-treated pots (G) and the lowest in those receiving macronutrient fertilizers and glyphosates (B). The highest total mesophilic fungal count (TMFC) was in pots with glyphosates and compost (F), and the lowest was in pots treated with macronutrient fertilizers and glyphosates (B). Pots treated with macronutrient fertilizers and glyphosates (B), macronutrient fertilizers (A), and micronutrient fertilizers (C) showed the lowest Fe and Zn levels. Maize in pots treated with macronutrient fertilizer combined with glyphosate (B) exhibited the lowest protein, fats, and carbohydrates. Notably, compost-treated soils showed the highest bacterial and fungal counts, Fe, and Zn concentrations, while micro-mineral fertilizer combined with glyphosate (B) depleted the soil. Agrochemical treatments negatively affected maize yield quality, indicating complex treatment-related changes in soil parameters. Full article

Purpose: This study explored the potential of a new in vitro method in evaluating antiplaque benefits from five sets of antimicrobial systems including cetylpyridinium chloride (CPC), stannous fluoride (SnF₂), Listerine essential oil mouthwashes (+/− alcohol), zinc chloride (ZnCl₂), and sodium fluoride. (NaF). Methods: Gingival dental plaque was collected and propagated using sterilized tryptic soy broth and sucrose, and then allocated into separate glycolysis and regrowth recipes for antiplaque evaluations. Glycolysis measurements (in duplicate) were recorded via pH microelectrode on plaque-treatment samples thermomixed (1200 rpm, 37 °C) for 4 h. For plaque regrowth, optical densities (in duplicate) were automatically collected on plaque-treatment samples using a microplate reader (linear shaking, 37 °C) from baseline to 4 h. Results: Calculations of percent change in pH and optical density were performed and analyzed for each set of antimicrobial treatment groups. Statistical analysis (one-way ANOVA, Student–Newman–Keuls stepwise comparison tests) revealed dose responses and significant differences (p < 0.05) among treatment groups, including between negative and clinically relevant positive controls. Conclusions: This lab method produces results consistent with published clinical observations. This glycolysis and plaque growth method is sensitive to antimicrobial mechanisms of action, and may offer a convenient and clinically relevant screening tool in the evaluation of putative antimicrobial agents and formulations. Full article

In this study, we used solid-state synthesis to prepare Ba[(Zn_xCo_1−x)_1/3(Nb_0.5Ta_0.5)_2/3]O₃ microwave ceramics for mobile communications. Compared with Ba[Zn_1/3(Nb_0.5Ta_0.5)_2/3]O₃, in the prepared materials, Co²⁺ substitution with Zn²⁺ improved the Q × f value and enabled densification and sintering at a lower temperature. We used X-ray diffraction (XRD) and scanning electron microscopy (SEM) to analyze the obtained microstructure. Ba[(Zn_xCo_1−x)_1/3(Nb_0.5Ta_0.5)_2/3]O₃ was found to have a 1:2 ordered hexagonal structure, and its Q × f value increased with the increase in sintering temperature. In this work, excellent microwave dielectric properties—τ_f = −0.7 ppm/°C, ε_r = 34.5, and Q × f = 110,000 GHz—were obtained by sintering Ba[(Zn_0.3Co_0.7)_1/3(Nb_0.5Ta_0.5)_2/3]O₃ at 1400 °C for 5 h. Full article

Zinc-ion hybrid capacitors (ZICs) can achieve high energy and power density, ultralong cycle life, and a wide operating voltage window, and they are widely used in wearable devices, portable electronics devices, and other energy storage fields. The design of advanced ZICs with high specific capacity and energy density remains a challenge. In this work, a novel kind of V, N dual-doped Ti₃C₂ film with a three-dimensional (3D) porous structure (3D V-, N-Ti₃C₂) based on Zn-ion pre-intercalation can be fabricated via a simple synthetic process. The stable 3D structure and heteroatom doping provide abundant ion transport channels and numerous surface active sites. The prepared 3D V-, N-Ti₃C₂ film can deliver unexpectedly high specific capacitance of 855 F g⁻¹ (309 mAh g⁻¹) and demonstrates 95.26% capacitance retention after 5000 charge/discharge cycles. In addition, the energy storage mechanism of 3D V-, N-Ti₃C₂ electrodes is the chemical adsorption of H⁺/Zn²⁺, which is confirmed by ex situ XRD and ex situ XPS. ZIC full cells with a competitive energy density (103 Wh kg⁻¹) consist of a 3D V-, N-Ti₃C₂ cathode and a zinc foil anode. The impressive results provide a feasible strategy for developing high-performance MXene-based energy storage devices in various energy-related fields. Full article

In order to understand the pollution degree and source of potentially toxic elements (PTEs) in groundwater around the accident site and evaluate their harm to human health, 22 groundwater samples were collected around the accident well, and the contents of As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, CH₂Cl₂ and C₂H₄Cl₂ were determined. On the basis of water quality evaluation, the source apportionment method combining qualitative and quantitative analysis was used to determine the main sources of PTEs in the region, and the health risk assessment model was used to evaluate the health risk of PTEs to the human body. The results show that pH, TDS, Th and COD all exceed the standard to varying degrees, among which TH is the index with the largest number exceeding the standard. The quality of the groundwater environment in the study area is at a very poor level, and the F value is between 7.25 and 8.49. The exposure results model showed that there was no non-carcinogenic risk of PTEs in the study area, and the health risk of oral intake in the exposed population was greater than that of skin contact. Compared with adults, children were more vulnerable to the health risk stress of PTEs in groundwater. The total carcinogenic risk is higher than the total non-carcinogenic risk. As, Cd and Cr are the primary factors causing carcinogenic health risks in this area. Principal component analysis (PCA) was used to analyze the sources of PTEs in groundwater, and three principal components were extracted. It was preliminarily determined that PTE pollution was mainly related to agricultural sources, anthropogenic industrial sources and industrial sedimentation sources. The results of positive definite factor matrix analysis (PMF) were basically similar to those of PCA, but PMF further clarified the contribution rate of three pollution sources, among which agricultural sources contributed the most to the accumulation of PTEs. Full article

[(Z)-2′-{2-C₆H₅-(4H)-oxazol-5-one}CHC₆H₄]₂Se (5, L¹) and [(Z)-4′-{2-C₆H₅-(4H)-oxazol-5-one}CHC₆H₄]₂Se (6, L²) were prepared, structurally characterized and used as ligands to obtain new metal complexes of types [MX(Lⁿ)] [L¹: M = Ag, X = OTf (7); M = Au, X = Cl (13); L²: M = Ag, X = OTf (8); M = Au, X = Cl (14)], [(MX)₂(Lⁿ)] [M = Ag, X = OTf, L¹ (9); L² (10)], [ZnCl₂(Lⁿ)] [L¹ (15); L² (16)] and [Ag(Lⁿ)][PF₆] [L¹ (11); L² (12)]. The silver complexes 7 and 8 were ionic species (1:1 electrolytes) in a MeCN solution, while in the solid state, the triflate fragments were bonded to the silver cations. Similarly, the 2:1 complexes 9 and 10 were found to behave as 1:2 electrolytes in a MeCN solution, but single-crystal X-ray diffraction demonstrated that compound 9 showed the formation of a dimer in the solid state: a tetranuclear [Ag(OTf)]₄ built through bridging triflate ligands was coordinated by two bridging organoselenium ligands through the nitrogen from the oxazolone ring and the selenium atoms in a 1κN:2κSe fashion. Supramolecular architectures supported by intermolecular C−H∙∙∙π, C−H∙∙∙O, Cl∙∙∙H and F∙∙∙H interactions were observed in compounds 4, 5 and 9. The compounds exhibited similar photophysical properties, with a bathochromic shift in the UV-Vis spectra caused by the position of the oxazolone ring on the phenyl ring attached to the selenium atoms. Full article

Chitin deacetylase (CDA) can catalyze the deacetylation of chitin to produce chitosan. In this study, we identified and characterized a chitin deacetylase gene from Euphausia superba (EsCDA-9k), and a soluble recombinant protein chitin deacetylase from Euphausia superba of molecular weight 45 kDa was cloned, expressed, and purified. The full-length cDNA sequence of EsCDA-9k was 1068 bp long and encoded 355 amino acid residues that contained the typical domain structure of carbohydrate esterase family 4. The predicted three-dimensional structure of EsCDA-9k showed a 67.32% homology with Penaeus monodon. Recombinant chitin deacetylase had the highest activity at 40 °C and pH 8.0 in Tris-HCl buffer. The enzyme activity was enhanced by metal ions Co²⁺, Fe³⁺, Ca²⁺, and Na⁺, while it was inhibited by Zn²⁺, Ba²⁺, Mg²⁺, and EDTA. Molecular simulation of EsCDA-9k was conducted based on sequence alignment and homology modeling. The EsCDA-9k F18G mutant showed a 1.6-fold higher activity than the wild-type enzyme. In summary, this is the first report of the cloning and heterologous expression of the chitin deacetylase gene in Euphausia superba. The characterization and function study of EsCDA-9k will serve as an important reference point for future application. Full article

Surface modification of the Ti6Al4V alloy (ASTM grade 5), with the fabrication of vertically oriented TiO₂ nanotubes, has been receiving increasing attention both as a way to provide advanced bioactive features and the ability to act as reservoirs for a localized, controlled drug release. In this work, TiO₂ nanotubes were grown on the surface of a Ti6Al4V alloy through electrochemical anodization. An ethylene glycol-based electrolyte containing 0.5 wt.% NH₄F and 2.5% (v/v) H₂O was used. Post-anodizing heat treatments at 500 °C in air atmosphere were performed to achieve a crystalline oxide layer with a higher mechanical stability. Following these treatments, Zn or Cu nanoparticles were incorporated into the nanotubular structures through electrodeposition processes. Then, the antimicrobial performance of the obtained surfaces was assessed against Staphylococcus epidermidis, a Gram-positive bacterium common in implant-related infections. Lastly, the cytotoxicity of the produced surface was evaluated against MC3T3-E1 mouse pre-osteoblast cells. In general, Cu-doped TiO₂ nanotubes presented an almost total antimicrobial action, while Zn doped samples had a lower, but still significant antibacterial effect. However, a highly cytotoxic effect against MC3T3-E1 cells was observed on all anodized samples due to the release of vanadium from the alloy. In spite of this, the surface modification reported in this work can be a valid solution for existing commercially available orthopedic implants, considering that similar solutions were already studied in in vivo assays. Full article