Search Results (5,236)

Rhenium metal is extensively utilized in the aerospace industry for the manufacturing of various superalloys due to its unique properties, and plays an indispensable role in the field of high technology. Rhenium resources are primarily associated with copper, molybdenum, and other metal ores. Ammonium perrhenate is predominantly derived from copper and molybdenum ore roasting flue gas scrubbers containing various impurities in the rhenium-containing contaminated acid. The complex composition of the contaminated acid renders the enrichment and purification of ammonium perrhenate more challenging, necessitating further research and development of the technology. This paper reviews the research progress in ammonium perrhenate enrichment and purification technology, encompassing chemical precipitation, adsorption, extraction, ion exchange, extraction chromatography, and recrystallization. It analyses the advantages and limitations of various methods, with the aim of providing a reference for future developments in ammonium perrhenate enrichment and purification technology. Furthermore, the paper presents a prospective view on the development of ammonium perrhenate enrichment and purification technology, focusing on the objective of obtaining more selective purification materials and more efficient purification techniques for ammonium perrhenate. Full article

The advent of the lithium-ion batteries (LIBs) has transformed the energy storage field, leading to significant advances in electronics and electric vehicles, which continuously demand more and more performant devices. However, commercial LIB systems are still far from satisfying applications operating in arduous conditions, such as temperatures exceeding 100 °C. For instance, safety issues, materials degradation, and toxic stem development, related to volatile, flammable organic electrolytes, and thermally unstable salts (LiPF₆), limit the operative temperature of conventional lithium-ion batteries, which only occasionally can exceed 50–60 °C. To overcome this highly challenging drawback, the present study proposes advanced electrolyte technologies based on innovative, safer fluids such as ionic liquids (ILs). Among the IL families, we have selected ionic liquids based on tetrabutylphosphonium and 1-ethyl-3-methyl-imidazolium cations, coupled with per(fluoroalkylsulfonyl)imide anions, for standing out because of their remarkable thermal robustness. The thermal behaviour as well as the ion transport properties and electrochemical stability were investigated even in the presence of the lithium bis(trifluoromethylsulfonyl)imide salt. Conductivity measurements revealed very interesting ion transport properties already at 50 °C, with ion conduction values ranging from 10⁻³ and 10⁻² S cm⁻¹ levelled at 100 °C. Thermal robustness exceeding 150 °C was detected, in combination with anodic stability above 4.5 V at 100 °C. Preliminary cycling tests run on Li/LiFePO₄ cells at 100 °C revealed promising performance, i.e., more than 94% of the theoretical capacity was delivered at a current rate of 0.5C. The obtained results make these innovative electrolyte formulations very promising candidates for high-temperature LIB applications and advanced energy storage systems. Full article

Caigua (Cyclanthera pedata (L.) Schrad.) is a traditional herbal remedy traditionally used in Latin America for its health benefits and to treat metabolic disorders, including diabetes. Despite interest in its herbal use, the phytochemical properties of caigua’s secondary metabolites are poorly known. This study aimed to isolate the main flavone glycosides from the leaves of caigua landrace cultivated in the Camonica Valley (Italy) using flash chromatography and evaluate their potential activity toward peroxisome proliferator-activated receptors (PPARs) and transient receptor potential (TRP) ion channels through luciferase and intracellular calcium assays. We found that the caigua species-specific flavone glycoside, chrysin-6-C-fucopyranoside, showed potent and selective activity toward PPARγ, with no effects on other PPAR subtypes or TRP channels. These findings indicate that the caigua plant could offer a safer alternative to conventional PPARγ agonists, whose use as antidiabetic drugs is limited by severe side effects that currently restrict the clinical use of conventional PPAR agonists. Full article

Gas chromatography–ion mobility spectrometry (GC-IMS) is a powerful technique in the field of food and flavor analysis specifically, as well as for the determination of volatile organic compounds (VOCs) in general. It offers high sensitivity and selectivity, combined with a robust design. Sample preparation is typically not required, and operating principles under ambient conditions facilitate routine analysis and usage at points of care. As of now, a plethora of applications of GC-IMS exist in the fields of food analysis, primarily for determining flavors and evaluating the authenticity of food. However, the general issue of peak tailing has, so far, not been addressed in IMS. Typical drift tube applications (DTIMS) are designed with emphasis to high detection sensitivities and feature large void volumes. This study aimed to develop an optimized IMS instrument design (“focus IMS”) which allows for signal mapping of eluting compounds. Due to an optimized flow architecture of sample and drift gases, in combination with an increased drift tube temperature, peak tailing is decreased significantly. In this study, the influence of drift gas flow and IMS cell temperature on the peak shape of several relevant allergenic terpenes was investigated. The peak quality optimization of DTIMS approaches for especially high-boiling substances facilitates the analysis of complex matrices, such as cosmetics, Citrus peel, and essence oils, as well as terpenes and terpenoids in general. Full article

Work has rarely been reported on a highly portable smartphone-based capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C⁴D). Herein, a highly portable phone-based CE (130 mm × 190 × 70 mm, 1.4 kg) with C⁴D and Bluetooth communication, as well as user-interface software, was developed for portable analysis. To demonstrate the device, six metal ions were selected as model analytes for verification and successfully applied to the detection of ions in tap water. The analytical performance highlighted that the runs and data analysis of the CE-C⁴D device could be controlled via the user interface based on smartphones. Furthermore, the experiments showed that (i) the linear ranges of six metal ions were between 6 and 1500 μmol/L with a correlation coefficient of more than 0.9934; (ii) the limit of detection (LOD) values were within 1.84–4.33 μmol/L; (iii) the intra-day deviations of migration time and peak area were 2.40–5.24% and 0.75–2.82% (n = 5), respectively. Although the LOD is not the most optimal among current portable devices, the results still indicated the satisfactory analytical performance and potential of the developed device, software, and method for portable separation and quantitation of analytes from various fields. Full article

This study examined the genetic and evolutionary features of influenza A/H3N2 viruses in Hangzhou (2010–2022) by analyzing 28,651 influenza-like illness samples from two sentinel hospitals. Influenza A/H3N2 coexisted with other subtypes, dominating seasonal peaks (notably summer). Whole-genome sequencing of 367 strains was performed on GridION platforms. Phylogenetic analysis showed they fell into 16 genetic groups, with multiple clades circulating simultaneously. Shannon entropy indicated HA, NA, and NS gene segments exhibited significantly higher variability than other genomic segments, with HA glycoprotein mutations concentrated in antigenic epitopes A–E. Antiviral resistance showed no inhibitor resistance mutations in PA, PB1, or PB2, but NA mutations were detected in some strains, and most strains harbored M2 mutations. A Bayesian molecular clock showed the HA segment exhibited the highest nucleotide substitution rate (3.96 × 10⁻³ substitutions/site/year), followed by NA (3.77 × 10⁻³) and NS (3.65 × 10⁻³). Selective pressure showed A/H3N2 strains were predominantly under purifying selection, with only sporadic positive selection at specific sites. The Pepitope model demonstrated that antigenic epitope mismatches between circulating H3N2 variants and vaccine strains led to a significant decline in influenza vaccine effectiveness (VE), particularly in 2022. Overall, the study underscores the complex circulation patterns of influenza in Hangzhou and the global importance of timely vaccine strain updates. Full article

The molten salt reactor is a fourth-generation nuclear power plant considered a long-term eco-friendly energy source with high efficiency and the potential for green hydrogen production. The selection of alloys for such reactors, which can operate for more than 30 years, is a primary concern because of corrosion by high-temperature molten salt. In this study, three Fe- and Ni-based alloys were selected as structural material candidates. Corrosion immersion tests were conducted in NaCl–KCl molten salt for 48 h at 800 °C and 40% RH conditions in an air environment. In the absence of moisture and oxygen removal, ClNaK salt-induced damage was observed in the investigated alloys. The corrosion behavior of the alloys was characterized using various techniques, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. The results show that the corrosion process can be explained by salt-induced surface damage, internal ion migration, and depletion to the surface. The corrosion rate is high in SS316L (16Cr-Fe), N10003 (7Cr-Ni), and C-276 (16Cr-Ni), in decreasing order. Based on the corrosion penetration, ion elution, and interfacial diffusion results, C-276 and N10003 are good candidates for structural materials for MSRs. Therefore, Ni-based alloys with high Cr content minimize surface damage and ion depletion in unpurified molten salt environments. This indicates that Ni-based alloys with high Cr content exhibit highly corrosion resistance. Full article

In this study, we report a green, one-step synthesis of fluorescent carbon quantum dots (PET-FCQDs) derived from polyethylene terephthalate (PET) waste using an environmentally friendly pyrolytic method. The PET-FCQDs were systematically characterized using techniques such as UV-Vis spectroscopy, fluorescence spectroscopy, ATR-FTIR, TGA, and fluorescence microscope, confirming their nanoscale size (2–50 nm), rich functional groups and thermal stability. Thermal stability and dynamics evaluated by the Coats–Redfern method showed endothermic reactions with an activation energy of 88.84–125.05 kJ/mol. Density functional theory studies showed a binding energy, highest occupied molecular orbital, lowest unoccupied molecular orbital, and energy gap of −675.39, −5.23, −5.07, and 0.17 eV, respectively. The as-synthesized PET-FCQDs demonstrated excellent optical properties with quantum yield ($\mathsf{\Phi }$) of 49.6% and were applied as a dual-mode fluorescent sensing probe for the detection of Pd²⁺, ciprofloxacin (CIP), and fluoxetine (FLX) in aqueous systems via fluorescence quenching and enhancement mechanisms. For Pd²⁺, the fluorescence emission intensity at 470 nm was quenched proportionally to the increasing concentration, while CIP and FLX induced fluorescence enhancement. The Stern–Volmer analysis confirmed strong interaction between the analytes and PET-FCQDs, distinguishing dynamic quenching for Pd²⁺ and static interactions for CIP and FLX. The method exhibited linear detection ranges of 1–10 mg/L for Pd²⁺, 50–150 µg/L for CIP, and 100–400 ng/L for FLX, with corresponding limits of detection (LOD) of 1.26 mg/L, 3.3 µg/L, and 134 ng/L, respectively. Recovery studies in spiked tap water and river water samples demonstrated the practical applicability of PET-FCQDs, although matrix effects were observed, particularly for FLX. This work not only highlights a sustainable route for PET waste upcycling but also demonstrates the potential of PET-FCQDs as cost-effective, sensitive, and versatile fluorescent probes for environmental monitoring of heavy metal ions and pharmaceutical pollutants. Further optimization of the sensing platform could enhance its selectivity and performance in real-world applications. Full article

Isothermal titration calorimetry (ITC), circular dichroism (CD) spectroscopy, and molecular dynamics simulations were applied to describe interactions between lipopeptides and decavanadate ions ([V₁₀O₂₈]⁶⁻). The selected lipopeptides are conjugates of the amide of the KR12 peptide, the smallest antimicrobial peptide derived from human cathelicidin LL-37, with lauric acid (C12-KR12) and myristic acid (C14-KR12). The smaller sizes of C12-KR12 and C14-KR12 compared to proteins allow for the rigorous characterization of their non-covalent interactions with highly negatively charged [V₁₀O₂₈]⁶⁻ ions. The stoichiometry of the resulting decavanadate–peptide complexes and the thermodynamic parameters (ΔG, ΔH, and TΔS) of the interactions were determined. The ITC results, supported by the MD simulation, showed that the binding of cationic lipopeptides for decavanadate is rather non-specific and is driven by enthalpic contributions resulting from electrostatic interactions between the positively charged residues of the peptides and the anionic decavanadate. Furthermore, the influence of temperature and the interactions with decavanadate ions on the stability of the α-helical structure of the lipopeptides were assessed based on CD spectra. Under the experimental conditions (50 mM sodium cacodylate buffer, pH 5), the peptides adopt an α-helical conformation, with C14-KR12 showing greater thermal stability. The interactions with vanadium species disrupt the α-helical structure and reduce its thermal stability. Full article

Nitrate pollution in drinking water is a major environmental and health issue. High levels of nitrates in water sources present serious risks to both the environment and public health, highlighting the need for immediate research and management efforts to reduce pollution sources and safeguard water resources for sustainable growth. This study investigates the elemental associations with nitrate concentrations in groundwater across the northeastern region of Saudi Arabia, employing diverse analytical techniques to assess water quality and develop sustainable management strategies. Spatial variations in nitrate levels were observed in both deep and shallow wells using GIS-based interpolation, revealing distinct patterns influenced by geological, hydrological, and anthropogenic factors. A strong linear correlation with a high coefficient of determination (R² of 0.99) between electrical conductivity and dilution factor suggests the potential interchangeability of ion-selective electrode methods and conductivity meters for EC determination. The study identified a positive correlation between nitrate concentration and electrical conductivity in groundwater samples (R² of 0.70), indicating that conductivity measurements could potentially serve as a proxy for estimating nitrate levels. However, a very weak negative correlation between nitrate and pH suggests other factors may have a more significant impact on groundwater pH. The research also highlights the strong positive correlation between nitrate and nitrate-nitrogen concentrations, reflecting their close chemical association in water. These findings contribute to the understanding of nitrate dynamics in groundwater and emphasize the importance of comprehensive water quality assessments. Future research should focus on elucidating factors influencing nitrate distribution in groundwater systems and developing more robust predictive models based on readily measurable water quality parameters. Full article

Addressing aquatic phosphate pollution requires advanced materials that combine high selectivity with recyclability. Here, we present a hierarchically structured composite integrating Mg-Fe layered double hydroxides (LDHs) with magnetic biochar derived from mulberry branches—an abundant agricultural byproduct. Through hydrothermal synthesis, the composite achieves a unique architecture combining Fe₃O₄-enabled magnetic recovery (2.63 emu·g⁻¹ saturation) with LDHs’ anion exchange capacity and biochar’s porous network. Systematic characterization reveals phosphate capture mechanisms dominated by hydrogen bonding through deprotonated carboxyl groups, inner-sphere complexation with metal oxides, and interlayer anion exchange, enabling 99.22% phosphate removal at optimal conditions (pH 6, 25 °C). Crucially, the material demonstrates exceptional selectivity over competing Cl⁻ and NO₃⁻ ions while maintaining 87.83% efficiency after three regeneration cycles via alkaline treatment. Kinetic and thermodynamic analyses confirm chemisorption-driven uptake aligned with pseudo-second-order kinetics (R² > 0.9998) and Langmuir monolayer adsorption (7.72 mg·g⁻¹ capacity). This waste-derived magnetic composite establishes a sustainable paradigm for eutrophication control, merging selective phosphate sequestration with energy-efficient recovery for circular water treatment applications. Full article

A novel design for vortex-assisted liquid–liquid microextraction (VALLME), combined with spectrofluorimetric determination (FLD), was proposed and successfully tested for determining picric acid (PA) in water samples. This fluorescence method is based on the formation of an ion associate (IA) through electrostatic interactions, which serves as the analytical species for fluorescence measurement in the presence of the basic polymethine dye Astrafloksin (AF). The approach aims to minimize the volume of the extraction phase, aligning with the principles of green analytical chemistry. The calibration curve was linear from 0.92 to 11.45 µg L⁻¹, with an R² of 0.9930. LOD was 0.40 µg L⁻¹. Density functional theory (DFT) calculations, supported by analysis of van der Waals and electrostatic interionic attraction, helped explain the experimentally observed selectivity of the AF cation for picrate compared to other selected phenols. Theoretical solubility descriptors of the proposed IA provided insight into the extraction of IA from water to the n-amyl acetate phase. This VALLME-FLD method represents a significant advancement in PA determination, characterized by high sensitivity, selectivity, and procedural simplicity. It minimizes the use of organic solvents, facilitates direct sample preparation, and shortens analysis time. The developed method was successfully applied to real samples. Full article

Considering the issues of significant ammonia volatilization loss and toxic gas emission associated with the conventional ammonia leaching method used in the resource utilization of cobalt-rich alloy slag, a novel approach involving selective complexation leaching of cobalt in an alkaline histidine solution has been proposed. Under conditions of 35 °C temperature, a molar ratio of histidine to cobalt of 1.5, pH of 8, a leaching period of 12 h, and a stirring speed of 300 rpm, the cobalt leaching rate from cobalt-rich alloy slag exceeds 95%. In contrast, the leaching rates for impurity metals such as iron, lead, and copper remain below 3%, demonstrating outstanding leaching selectivity. Leaching kinetics calculations indicate that the rate-controlling step is chemical reaction control, with an apparent activation energy of 64.32 kJ/mol. Through the use of FTIR and XPS characterization techniques, it has been confirmed that histidine molecules form a stable complex with cobalt ions via the dual coordination of the carboxyl (COO⁻) and amino (-NH₂) groups. This distinctive bifunctional synergistic coordination mechanism markedly enhances leaching selectivity and reaction efficiency. Full article

Thorium is a notable candidate for resolving uranium shortage caused by the global application of nuclear power generation. Uranium extraction from seawater is another attempt to handle its source deficiency, however, vanadium is one of the main competitive elements in that process. Exploration of probes which can discriminatively detect thorium and vanadium from uranium has primary significance for their further separation and for environmental protection. Herein, N′-(2,4-dihydroxybenzylidene)-4-hydroxylphenylhydrazide, AOH, is used as sensor for Th⁴⁺ and vanadyl (VO²⁺) determination. AOH demonstrates a specific “turn-on” fluorescence selectivity towards Th⁴⁺ over f-block and other foreign metal ions, with a detection limit (LOD) of 7.19 nM in acidic solution and a binding constant of 9.97 × 10⁹ M⁻². Meanwhile, it shows a “turn-off” fluorescence response towards VO²⁺ over other metal ions at the coexistence of Th⁴⁺, with a LOD of 0.386 μM in the same media and a binding constant of 4.54 × 10⁴ M⁻¹. The recognition mechanism, based on HRMS, ¹H NMR, and FT-IR results, demonstrates that VO²⁺ causes the fluorescence quenching by replacing Th⁴⁺ to coordinate with AOH. In real water detection tests, Th⁴⁺ and VO²⁺ exhibited satisfying recoveries. These findings expand the application of sensors in nuclide pollution control. Full article

This paper presents entropy measurements for a large set of commercial Li-ion cells. We present entropy data on full cells with a variety of common Li-ion cell electrode chemistries; graphite, hard carbon, lithium-titanium-oxide (LTO), lithium cobalt-oxide (LCO), nickel manganese cobalt oxides (NMC), nickel cobalt aluminium oxide (NCA), lithium iron-phosphate (LFP), as well as electrodes with mixes of these. All data were collected using an accelerated potentiometric method in steps of approximately 5% State-of-Charge (SoC) across the full SoC window. We observe that the entropy profiles depend on the chemistry of the Li-ion cells, but that they also vary between different commercial cells with the same chemistry. Entropy contributions are quantified with respect to both, their means, positive and negative contributions as well as their SoC variation. In addition, we present how different cyclic ageing temperatures change the entropy profiles for a selected commercial Li-ion cell through ageing. A clear difference in entropy profiles is observed after a capacity loss of 20%. This difference can be attributed to different ageing mechanisms within the Li-ion cells, leading to changes in the balancing of electrodes, as well as changes in the electrode materials. Full article