Search Results (905)

To investigate the seasonal characteristics, sources, and regional transport patterns of precipitation components in the high-elevation mountainous regions, field sampling was conducted at Mt. Heng (Hunan, South China) from June 2021 to May 2022. In total, 114 precipitation samples were collected and subjected to chemical analysis, including pH, major inorganic ions, and heavy metals. During the study period, the precipitation at Mt. Heng was generally weakly acidic. The concentrations of metals and acidic anions (NO₃⁻ and SO₄²⁻) were higher in the winter and lower in the summer, whereas the concentration of the primary neutralizing cation, NH₄⁺, peaked during the summer. An association was observed between precipitation pH and metal concentrations, whereby acidic precipitation samples exhibited marginally elevated metal concentrations overall. An additional analysis of winter precipitation chemistry at Mt. Heng revealed an increasing trend of ions from 2015 to 2018, followed by a decrease from 2019 to 2021. This trend coincided with the concentrations of NO₂ and SO₂ in the surrounding cities, reflecting the results of clean air actions. The results of the source analysis revealed five major sources: secondary sources (41.5%), coal combustion (24.7%), a mixed source of biomass burning and aged sea salt (11.6%), dust (10.8%), and industrial emissions (11.4%). Backward trajectory cluster analysis revealed that air masses originating from the northern regions were generally more polluted than those from the southern regions. This study provides fundamental data and scientific support for regional atmospheric pollution control and ecological protection in South China. Full article

Over the last decade, bark beetle outbreaks have significantly impacted forests in Central Europe, causing extensive loss of forest cover. We evaluated the impact of partial deforestation in three mountain forest catchments in the Jeseníky Mountains, comparing them with the unaffected Červík catchment (Beskydy Mountains) and the severely affected Pekelský stream catchment (Czech-Moravian Highlands). Atmospheric deposition in the catchments was similar, with total element input driven primarily by precipitation volumes rather than ion concentrations. We did not observe the hypothesized increase in DOC and nitrogen export, although nitrate outflow was slightly higher than atmospheric input in two cases. Significant export of calcium, magnesium, and bicarbonates was driven mainly by the geology of the individual catchments. The limited impact of bark beetle outbreaks on DOC dynamics can be attributed to the relatively low proportion of clear-cut areas and the rapid development of ground vegetation on impacted sites. Full article

Chromium complexes with triamidoamine derivatives bearing bulky substituents at the terminal positions of the ligands, tris(2-(3-pentylamino)ethyl)amine (H₃L^Pen) and tris(2-dicyclohexylmethylaminoethyl)amine (H₃L^Cy), are prepared: [{Cr(L^Pen)}₂(μ-N₂)] (1), [{CrK(L^Pen)(μ-N₂)(Et₂O)}₂] (2), [CrCl(L^Pen)] (3), [Cr(L^Cy)] (4), [CrK(L^Cy)(μ-N₂)(18-crown-6)(THF)] (5(THF)), and [CrCl(L^Cy)] (6). The preparation of these complexes is confirmed by X-ray diffraction analysis. Complexes 1, 2, and 5(THF) have coordinated dinitrogen molecules, with N–N bond lengths of 1.185(3), 1.174(9), and 1.162(3) Å, respectively. These lengths are significantly elongated compared to that of a free dinitrogen molecule (1.10 Å), indicating that the N₂ ligands are activated. The ν(¹⁴N–¹⁴N) values of 1, 2, and 5(THF) are 1715 cm⁻¹ for 1 (Raman, in solution), 1787, 1743 cm⁻¹ for 2 (IR, in solid), and 1824 cm⁻¹ for 5(THF) (IR, in solid), respectively. These values are markedly smaller than free nitrogen (2331 cm⁻¹), confirming that the dinitrogen is interacting with the metal ions and is activated. The structures of 2 and 5(THF) in solution are also studied by ¹H NMR and solution IR spectroscopies. ¹H NMR spectra of these complexes reveal that the peaks of 2 and 5(THF) are observed in the diamagnetic region, whereas those for the other complexes (1, 3, 4, and 6) exhibit paramagnetic shifts. The reactions of these complexes with K[C₁₀H₈] and HOTf under N₂ in THF yield hydrazine and a small amount of ammonia; however, they are not catalytic. The ¹H NMR and IR spectra of the products obtained by reacting 1 or 3 with reductant K in THF under N₂ atmosphere indicate that 2 is formed based on spectral agreement. Similarly, upon examining for 4 or 6, it is confirmed that a species similar to 5(THF) is generated. Full article

Arsenic contamination demands innovative, sustainable remediation. This study presents a fuzzy approach for synthesizing a magnetic biochar nanocomposite from pecan shell agricultural waste for efficient arsenic removal. Using a Multi-Input Fuzzy Rules Emulated Network (MiFREN), a systematic investigation of the synthesis process revealed that precursor type (biochar), Fe:precursor ratio (1:1), and iron salt type were the most significant parameters governing material crystallinity and adsorption performance, while particle size and N₂ atmosphere had a minimal effect. The MiFREN-identified optimal material, the magnetic biochar composite (FS7), achieved > 90% arsenic removal, outperforming the least efficient sample by 50.61%. Kinetic analysis confirmed chemisorption on a heterogeneous surface (q_e = 12.74 mg/g). Regeneration studies using 0.1 M NaOH demonstrated high stability, with FS7 retaining > 70% removal capacity over six cycles. Desorption occurs via ion exchange and electrostatic repulsion, with post-use analysis confirming structural integrity and resistance to oxidation. Application to real groundwater from the La Laguna region proved highly effective; FS7 maintained selectivity despite competing ions like ${Na}^{+}$, ${Cl}^{-},$ and ${SO}_4^{2-}$. By integrating AI-driven optimization with reusability and real contaminated water, this research establishes a scalable framework for transforming agricultural waste into a high-performance adsorbent, supporting global Clean Water and Sanitation goals. Full article

This study investigated the site-specific ionic composition and wet deposition loads of rainwater collected from eight actively cultivated agricultural regions across South Korea, with the aim of quantifying spatial and seasonal variability and interpreting how regional agricultural characteristics and surrounding site conditions influence major ion concentrations and deposition patterns. Rainfall samples were obtained using automated samplers and analyzed via high-performance ion chromatography for major cations (Na⁺, $\mathrm{N}{\mathrm{H}}_4^{+}$, K⁺, Ca²⁺, Mg²⁺) and anions (Cl⁻, $\mathrm{N}{\mathrm{O}}_3^{-}$, $\mathrm{S}{\mathrm{O}}_4^{2-}$, $\mathrm{N}{\mathrm{O}}_2^{-}$). The results revealed significant seasonal fluctuations in ion loads, with $\mathrm{N}{\mathrm{H}}_4^{+}$ (peak 1.13 kg/ha) and K⁺ (peak 0.25 kg/ha) reaching their highest levels during summer due to increased fertilizer use and crop activity. Conversely, Cl⁻ peaked in winter (2.11 kg/ha in December), particularly in coastal regions, likely influenced by de-icing salts and sea-salt aerosols. Correlation analysis showed a strong positive association among $\mathrm{N}{\mathrm{H}}_4^{+}$, $\mathrm{N}{\mathrm{O}}_3^{-}$, and $\mathrm{S}{\mathrm{O}}_4^{2-}$ (r = 0.89 and r = 0.84, respectively), indicating shared atmospheric transformation pathways from agricultural emissions. Ternary diagram analysis further revealed regional distinctions: coastal regions such as Gimhae and Muan exhibited Na⁺ and Cl⁻ dominance, while inland areas like Danyang and Hongcheon showed higher proportions of Ca²⁺ and Mg²⁺, reflecting differences in aerosol sources, land use, and local meteorological conditions. These findings underscore the complex interactions between agricultural practices, atmospheric processes, and local geography in shaping rainwater chemistry. The study provides quantitative baseline data for evaluating non-point source pollution and developing region-specific nutrient and soil management strategies in agricultural ecosystems. Full article

Water-soluble inorganic ions (WSIIs) are major components of PM_2.5 and play a prominent role in atmospheric acidification. Previous studies have mainly focused on urban areas, whereas research pertaining to county-level cities remains comparatively limited. To fill this gap, PM_2.5 samples were collected from March 2018 to February 2019 in Botou, a county-level city in the Jing–Jin–Ji region. Seasonal variation of WSII were studied, and their sources was apportioned by Positive Matrix Factorization (PMF) model. Annual PM_2.5 concentrations were 79.15 ± 48.44 mg/m³, which is 2.26 times of the Level II standard limit specified the National Ambient Air Quality Standard. Nitrate (NO₃⁻) was the most abundant ion, followed by ammonium (NH₄⁺) and sulfate (SO₄²⁻). The secondary inorganic aerosols (SIA, i.e., SO₄²⁻, NO₃⁻, and NH₄⁺) constituted 35.1± 4.7% of PM_2.5 mass. PM_2.5 mass, SO₄²⁻, NO₃⁻, NH₄⁺, K⁺, and Cl⁻ showed highest concentrations in winter. Ammonium salts were existed as ammonium sulfate ((NH₄)₂SO₄) and ammonium nitrate (NH₄NO₃) in spring, summer, and autumn, while it also can be existed as ammonium chloride (NH₄Cl) in winter. PMF analysis shows that the sources of WSIIs dominated by secondary source and followed by biomass burning. These results highlight the need for improved controls on gaseous precursors (NH₃, NO₂ and SO₂) and biomass burning to effectively reduce PM_2.5. Full article

The observed shortage of water resources in the western and southern regions of the Russian Federation may soon affect the territory of the Republic of Bashkortostan. An increase in the share of groundwaters can help to solve this problem. To provide the population of the republic with water resources, the groundwater of magnesium–bicarbonate-type from the Kraka ophiolite massifs can be used. The massifs occur on the western slope of the Southers Urals. In this work we studied ultramafic rocks and their influence on the formation of the chemical composition of water. The research area is located in the northern part of the Zilair synclinorium, which occurs within the Central Ural megazone. In terms of hydrogeology, of particular importance to the territory of the synclinorium is the Zilair basin of fracture waters of the second order, which is part of the Uralian hydrogeologic folded zone. The ultramafic rocks from the studied area have consistently high CaO/Al₂O₃ ratios (0.4–1.6), which indicates the widespread development of parageneses with participation of clinopyroxene and a low degree of depletion of the primitive mantle source. Because of the complex geological structure of the area, water samples collected from both water points in the Kraka massifs, and the surrounding Early–Middle Paleozoic rocks were analyzed for major ions using a laboratory method to identify possible hydro-geochemical zoning. A statistical analysis was then conducted based on the obtained anion–cation composition data. From the viewpoint of the hydrolytic concept, the formation of the chemical composition of groundwater takes place due to the removal of Mg²⁺ from the rock-forming minerals of ultramafic rocks (olivine and pyroxene) and the supply of Na⁺, K⁺, Ca²⁺, and SO₄²⁻ Cl⁻ from atmospheric precipitations. The bicarbonate anion has a complex nature, where both biochemical processes in the soil and atmospheric precipitation play a significant role. Magnesium–bicarbonate-type of waters, due to low mineralization (to 1 g/L) and the majority of other geochemical parameters (pH of the medium, and content of Na, K, Ca, SO₄, and Cl), whose values that are within the limits set by the World Health Organization (WHO), can be used as drinking water. The increased values of total hardness (0.20–3.39 mmol/L) in accordance with the regulatory document SanPiN 1.2.3685–21, adopted by the Russian Federation, do not exceed the maximum permissible concentrations (up to 7.00 (10.00) mEq/L or 3.50 (5.00) mmol/L). The high magnesium content, in accordance with GOST (state standard) R 54316–2020, allows the magnesium–bicarbonate waters of the Kraka massifs to be classified as table mineral waters for the treatment of various diseases (including hypomagnesemia). Full article

In this study, thin molybdenum nitride (MoN_x) layers were directly synthesized on molybdenum foil via thermal treatment under an NH₃ atmosphere, and their phase evolution, structural characteristics, and electrochemical performance were investigated. The thickness and morphology of the MoN_x layers were controlled by varying ammonolysis time and temperature, while subsequent annealing in N₂ converted the nitride layer into MoO₂. Meanwhile, oxidation in air yielded crystalline MoO₃ layers. X-ray diffraction and X-ray photoelectron spectroscopy confirmed progressive oxidation of molybdenum, with Mo 3d binding energies increasing in the sequence of Mo < MoN_x < MoO₂ < MoO₃, consistent with their nominal oxidation states. Electrochemical characterization revealed that both MoN_x/Mo and MoO₂/Mo electrodes exhibit notable pseudocapacitive behavior in 0.5 M H₂SO₄ electrolyte, with areal specific capacitances reaching up to 520 mF cm⁻² at 10 mV s⁻¹. Increasing layer thickness led to enhanced capacitance, likely due to an increase in the electrochemically accessible surface area and the extension of ion diffusion pathways. MoO₂-coated samples showed stronger faradaic contribution and superior rate capability compared to MoN_x counterparts, along with a gradual shift from predominantly electric double-layer capacitance toward hybrid pseudocapacitive charge storage mechanisms. Full article

A novel and facile route for intercalating alkali-metal ions and ammonium ions into the layered mixed-ion compound tungsten oxychloride (WO₂Cl₂) has been developed using the iodide–triiodide redox couple as a mild redox-active reagent. Unlike traditional intercalation techniques employing highly reducing and air-sensitive reagents such as n-butyllithium, alkali triethylborohydride, and naphthalenide, the I⁻/I₃⁻ redox system operates at a moderate potential (0.536 V vs. SHE), enabling safer handling under ambient conditions without stringent inert-atmosphere requirements. This redox pair promotes the reduction of W⁶⁺ to W⁵⁺, thereby facilitating cation insertion into the van der Waal (vdW) gaps of WO₂Cl₂. This method uniquely enables ammonium ion intercalation into WO₂Cl₂, a first for this system. Intercalation was confirmed by X-ray diffraction, scanning electron microscopy (SEM/EDS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), with measured lattice expansion correlating well with Shannon ionic radii and coordinating environments. Electrical transport measurements reveal a transition from insulating WO₂Cl₂ to a semiconducting phase for K_0.5WO₂Cl₂, exhibiting a resistance drop of over four orders of magnitude. This work demonstrates the I⁻/I₃⁻ couple as a general, safe, and versatile method for layered mixed-anion materials, broadening the chemical toolkit for low-temperature, solution-based tuning of structures and properties. Full article

Ionic propulsion, where charged particles, ions, are produced between electrodes and accelerate towards the negative electrode, has practical applications as a propulsion system in the space industry; however, its adoption to in-atmosphere ionic propulsion is relatively new and faces different challenges. A high potential difference is required to achieve a corona discharge between a positive and negative electrode. In this work, we will explore the feasibility of ionic propulsion using CFD modelling to replicate the effect of the ions, with a future aim of improving efficiency. The ionization region is modelled for a 15 kV potential difference, which is replicated with a velocity inlet, based on experimental data. The output velocity from the numerical simulation shows the same trend as theoretical predictions but significantly underestimates the magnitude of the ionic wind when compared with theoretical estimates. Further modelling is highlighted to improve predictions and assess if the theoretical model overestimates the ionic wind. Full article

High-phosphorus iron ore can be utilized using a technical route of hydrogen-based shaft furnace reduction, followed by electric arc furnace (EAF) melting separation. In shaft furnace reduction, both pellet and lump ore could serve as feedstock. To optimize the charge pattern in the H₂-based shaft furnace, an investigation of the reduction behavior of high-phosphorus iron ore lumps and pellets under H₂ atmosphere was conducted. Results revealed distinct differences between the lumps and the pellets in terms of physicochemical characteristics, maximum reduction fractions, microstructure evolution, and reduction kinetics characteristics. The lumps exhibited a notable presence of oolitic structures with 60.08 wt.% total iron, 11.69 wt.%. Fe²⁺ ion, and 0.80 wt.% phosphorus. Under H₂ atmosphere, the lumps achieved a maximum reduction fraction of 0.80. During the reduction, fayalite formed in the early stage, and glassy phases appeared in the later stage. The rate-controlling steps included internal gas diffusion, interfacial chemical reaction, and solid-state diffusion of ions. In contrast, the oolitic structures were completely disrupted in the pellets. The pellets contained 56.01 wt.% total iron, 0.86 wt.% Fe²⁺ ions, and 0.73 wt.% phosphorus. The pellets reached a full reduction under H₂ atmosphere with negligible formation of fayalite and glassy phases. The rate-controlling steps included internal gas diffusion and interfacial chemical reaction. Full article

With the increasing volumes of spent lithium-ion batteries from electric vehicles and the concurrent increase in raw materials cost for cathode production, finding effective methods for recycling battery materials has become critically important. This study investigated a pyrometallurgical approach using microwave irradiation to achieve carbothermal reduction of LiCoO₂. FactSage thermodynamic calculations were performed for process simulation and an infrared thermal camera was employed for temperature measurements, allowing the authors to optimize the process parameters to obtain metallic cobalt. Specifically, the research included microwave experiments on mixed black mass samples of anode and cathode materials in different proportions, treated at varying power levels and exposure times under air atmosphere. The effect of the process parameters and therefore of the temperature on microstructure was studied with SEM-EDS and XRD analysis. The feasibility of a wet magnetic separation method between cobalt and lithium compounds formed during the reaction was also evaluated. The results obtained from the final separation process indicated that individual compounds can be obtained at the end of the cycle; moreover, the optimization of time, temperature, and graphite additions during the tests allowed the authors to obtain promising results. Full article

Ions of Gd³⁺ and Yb³⁺ have radii similar to those of Zr⁴⁺, enabling them to form limited solid solutions in the ZrO₂ lattice through substitution. After solid solution formation, oxygen vacancy defects and complex defect aggregates are generated, which are crucial for stabilizing the high-temperature phase structure and reducing thermal conductivity. Therefore, in this study, 8 wt% Y₂O₃ and 5 wt% Yb₂O₃ were doped with 5 wt%, 10 wt%, and 15 wt% Gd₂O₃, respectively, to stabilize zirconia powders. GYYZO thermal barrier coatings (TBCs) were fabricated via atmospheric plasma spraying (APS). Subsequently, the GYYZO coatings with different Gd₂O₃ addition amounts were subjected to continuous thermal shock cycling at 1100 °C for 10, 30, 60, 90, and 150 cycles. The results indicate that the incorporation of Gd₂O₃, Yb₂O₃, and Y₂O₃ leads to the formation of stable tetragonal ZrO₂ phase in the GYYZO coatings. Although increasing the Gd₂O₃ addition amount reduces the thermal conductivity of the coatings, excessive Gd₂O₃ addition causes coating spallation. The GYYZO coating with 10 wt% Gd₂O₃ exhibits the lowest thermal conductivity of 0.59 W/(m·K). Additionally, the GYYZO coating with 10 wt% Gd₂O₃ can withstand thermal cycling for 150 cycles, while the one with 5 wt% Gd₂O₃ can endure 90 of thermal cycles. In contrast, the 8YSZ coating cracks and spalls after 60 thermal cycles. These findings demonstrate that doping ZrO₂ with Gd₂O₃, Yb₂O₃, and Y₂O₃ can enhance the thermal cycling resistance of the coatings and effectively reduce their thermal conductivity, but excessive Gd₂O₃ addition will decrease the coating adhesion strength. Full article

Background: Glucose, a central carbohydrate in higher organisms’ metabolism, can undergo extensive oxidative modification under conditions of excessive inflammation or elevated reactive oxygen and nitrogen species (RONS). Such modifications yield glucose oxidation products (GOPs) with potential biological relevance and toxicity. This study aimed to systematically characterize GOP formation under defined oxidative conditions generated by gas plasma treatment. Methods: D-glucose solutions were prepared at 0.25 mM (hypoglycemic/diabetic range), 2.5 mM (sub-physiological), and 25 mM (peritoneal dialysis fluid). Samples were exposed for up to 20 min to the atmospheric-pressure argon plasma jet kINPen, which produces a wide spectrum of RONS. Treatment time-dependent glucose oxidation was assessed by high-resolution mass spectrometry (HRMS) and tandem mass spectrometry (MS/MS) to identify the oxidation products. Results: Gas plasma exposure generated various oxidation products and their abundance profiles depended on initial glucose concentration and treatment duration. Identified products included 2-keto-D-glucose, 3-deoxyglucosone (3DG), 3,4-dideoxyglucosone-3-ene (3,4DGE), furaldehyde, methylglyoxal, and acetaldehyde. HRMS/MS analysis confirmed diagnostic fragment ions for each GOP and revealed distinct formation across the model scenarios. Conclusions: Cold gas plasma induces a spectrum of glucose oxidation products under biomedically relevant glucose levels. The identified GOPs, many of which have known cytotoxic or signaling properties, provide mechanistic insight into glucose oxidation in inflamed or oxidative microenvironments. These findings support the utility of plasma-based oxidative models for studying GOP-associated biological effects and potential pathophysiological consequences. Full article

The biogeochemical cycling of nitrogen (N) in natural waterbodies, ranging from freshwaters to estuaries and seawater, is fundamental to the health of aquatic ecosystems. Anthropogenic pressures (agricultural runoff, atmospheric deposition, and wastewater discharge) have profound effects on these cycles, leading to widespread problems, such as eutrophication, harmful algal blooms, and contamination of drinking water sources. Monitoring of different N-species—ammonium (NH₄⁺), nitrite (NO₂⁻), nitrate (NO₃⁻) ions, dissolved organic nitrogen (DON), and total nitrogen (TN)—is of crucial importance to protect and mitigate environmental harm. Traditional analytical methodologies, while providing accurate laboratory data, are hampered by logistical complexity, high cost, and the inability to capture transient environmental events in near-real time. In response to this demand, miniaturised microfluidic technologies offer the opportunity for rapid, on-site measurements with significantly reduced reagent/sample consumption and the development of portable sensors. Here, we review and critically evaluate the principles, state-of-the-art applications, inherent advantages, and ongoing challenges associated with the use of microfluidic colorimetry for N-species in a variety of environmental waterbodies. We explore adaptations of classical colorimetric chemistry to microfluidic-based formats, examine strategies to mitigate complex matrix interferences, and consider future trajectories with autonomous platforms and smart sensor networks for simultaneous multiplexed N-species determination. Full article