Search Results (206)

Chronic environmental exposure to mixtures of heavy metals like manganese (Mn) and vanadium (V) has been associated with Parkinson’s disease (PD). We investigated the poorly understood neurotoxic effects of Mn/V co-exposure on PD-relevant behavioral phenotypes in transgenic mice expressing the human alpha-synuclein (αSyn) A53T mutant. C57BL/6 wild-type (WT) and transgenic A53T mice were intranasally co-exposed to 100 µg MnCl₂ and 75 µg V₂O₅ five times weekly for three months, simulating a 5-day workweek. This led to significant Mn/V accumulation in the brain. Exploratory locomotor activity declined significantly in Mn/V-treated A53T mice, but not in Mn/V-treated WT mice when compared to their respective vehicle controls. Motor coordination, assessed via a forced locomotor activity test, was not significantly affected in either group. In Mn/V-treated A53T mice, olfactory deficits were present, but not in Mn/V-treated WT mice. Behavioral despair, assessed by tail suspension and forced swim tests, was not induced by Mn/V co-exposure in any group compared to their vehicle controls. Mn/V-treated A53T mice exhibited anxiety-like behavior and hyperactivity. These findings suggest that Mn/V co-exposure exacerbates neurotoxic effects in A53T mice, with a more pronounced effect in males, providing insight into the role of metal mixture exposure in environmentally linked Parkinsonism. Full article

Hypo-peritectic steels are susceptible to interfacial cracking during thin-slab continuous casting, in which non-metallic inclusions play a critical role. This study systematically investigates the effects of inclusion type and morphology on interface cracking behavior in the steel matrix, with the aim of improving billet shell quality. Hot tensile experiments were conducted using a Gleeble 3800 thermal simulator, and a finite element–based cohesive zone model was developed to simulate inclusion-induced crack nucleation and propagation. The results demonstrate that inclusions markedly influence interfacial stress distribution and damage evolution. The maximum interfacial stresses associated with MnS, Al₂O₃, and composite inclusions are 20.7, 23.4, and 30.5 MPa, respectively. Owing to severe stress concentration at sharp corners, composite inclusions exhibit the earliest crack nucleation at an applied stress of 11.3 MPa and the highest energy dissipation. In all cases, cracks initially nucleate at the location of maximum tensile stress (α = 90°), propagate along the interface, and subsequently penetrate into the matrix, ultimately leading to failure. The strong agreement between numerical simulations and experimental results confirms that angular inclusions accelerate damage by disrupting matrix continuity. These findings provide theoretical guidance for improving hypo-peritectic steel quality through inclusion morphology control during continuous casting. Full article

The new alluaudite-group mineral manganobadalovite (IMA 2020-035), ideally NaNaMn(MgFe³⁺)(AsO₄)₃, was found in the Arsenatnaya fumarole, the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption 1975–1976, Tolbachik volcano, Kamchatka peninsula, Far-Eastern Region, Russia. Manganobadalovite is a fumarolic mineral, and its aggregates are found overgrowing basalt scoria or exhalative hematite crystal crusts. Associated minerals are badalovite, hematite, cassiterite, sanidine, glauberite and metathénardite. Manganobadalovite occurs as prismatic to equant crystals up to 0.8 mm long typically combined in open-work clusters; it also forms grains that are irregular in shape and cavernous granular crusts up to 0.5 cm. The mineral is transparent, with vitreous luster, and its color varies from red to yellow. Manganobadalovite is brittle and has a noticeable cleavage in one direction and uneven fracture. The calculated density is 4.108 g cm⁻³. Manganobadalovite is optically biaxial (+), α = 1.790 (7), β = 1.800 (7), γ = 1.815 (8) and 2V_meas = 80 (5)°. Chemical composition (wt.%, electron-microprobe): Na₂O 8.75, K₂O 0.17, MgO 5.32, CaO 3.68, MnO 10.09, CuO 0.42, Al₂O₃ 0.18, Fe₂O₃ 13.90, V₂O₅ 0.42, As₂O₅ 56.75, total 99.68. The empirical formula calculated based on 12 O apfu is Na_1.69K_0.02Ca_0.39Mn_0.85Mg_0.79Cu_0.03Fe³⁺_1.04Al_0.02(As_2.96V_0.03)_∑2.99O₁₂. The crystal structure was solved using single-crystal XRD data, R = 2.30%. Manganobadalovite is monoclinic, C2/c, a = 12.1848(5), b = 12.8924(4), c = 6.6970(3) Å, β = 113.113(5)°, V = 967.60(7) ų and Z = 4. The strongest reflections of the powder XRD pattern are [d,Å(I)(hkl)]: 6.43(30)020, 3.589(32)(−131, 310), 3.215(38)(040, −112), 3.079(23)(221, 002), 2.941(32)(−312, −222, −331), 2.852(15)(041), 2.788(100)(330, 400, 240, 022), 2.649(22)(−402, 112), 2.626(25)(−132). Manganobadalovite is named as an analogue of badalovite NaNaMg(MgFe³⁺)(AsO₄)₃ with Mn²⁺ prevailing in the M(1) site. Full article

Dysphania ambrosioides is a widely distributed species with a traditional use in folk medicine, but it exhibits marked chemical variability that limits its standardization. This study is the first to characterize the essential oil (EO) of three Ecuadorian populations—Arenillas (ARE), Pasaje (PAS) and Piñas (PIN)—using gas chromatography–mass spectrometry/flame ionization detection (GC-MS/FID), and to correlate its composition with edaphic properties and antioxidant activity. Chemical profiles revealed three distinct chemotypes: ARE (α-terpinene 65.35%, o-cymene 24.83% and ascaridole 3.30%), PAS (α-terpinene 56.31%, o-cymene 10.09% and ascaridole 10.84%) and PIN (α-terpinene 56.89%, o-cymene 17.07% and ascaridole 7.60%). The EO yield was low (0.030–0.064% w/w), coinciding with acidic and nutrient-poor soils. On the other hand, PAS, with its neutral soil and high nitrogen, produced the highest number of oxygenated compounds. Only PAS exhibited strong ABTS radical-scavenging activity (SC₅₀ = 37.99 ± 1.01 µg/mL). In contrast, ARE showed weak activity (SC₅₀ = 424 ± 1.01 µg/mL), while PIN showed moderate activity (SC₅₀ = 112.26 ± 1.01 µg/mL), which was correlated with its high total phenol content (298.48 mg EAG/L). The 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity was low in all samples. Principal component analysis (PCA) confirmed clear separation of the chemotypes, which was linked to edaphic factors such as pH, heavy metals (Cu, Fe and Mn) and organic matter. These findings suggest that edaphic conditions may modulate the chemical composition and antioxidant activity of D. ambrosioides, indicating a potential approach for the sustainable selection of plant material. Full article

Although excessive manganese (Mn) exposure is known to cause neuromotor function in cases of poisoning, its effect on grip strength (a neuromotor marker) in older adults at environmental levels remains unclear. To investigate this issue, we conducted an integrated investigation combining epidemiology and animal experimentation to examine the association between urinary manganese and grip strength. A cross-sectional study of 375 elderly men (60–74 years) was conducted in Guangxi, China, from 2016 to 2017. Urinary Mn concentrations were determined by ICP-MS, and their associations with grip strength were evaluated using generalized linear models and restricted cubic splines. In parallel, 32 six-week-old male C57BL/6J mice were exposed to 0, 5, 10, or 15 mg/kg MnCl₂·4H₂O via intraperitoneal injection for 6 weeks. Forelimb grip strength of the mice was measured after the final exposure, and mRNA expression of inflammatory markers and cytokines (C reactive protein (CRP), interleukin (IL)-6, and tumor necrosis factor (TNF)-α in triceps) in triceps tissue was quantified. The median urinary Mn concentration in the study population was 0.22 μg/g creatinine. After adjusting for confounders, urinary Mn was inversely associated with hand grip strength (highest vs. lowest tertile: β = −3.57 kg; 95% CI: −5.68 to −1.47; p-trend = 0.007). Similarly, in male C57BL/6J mice, grip strengths declined significantly with increasing Mn exposure (p-trend < 0.0001), accompanied by upregulation of the mRNA levels of CRP, IL-6 and TNF-α in muscle tissue. Together, our findings suggest that environmental manganese exposure is inversely associated with grip strength in elderly men. While the manganese doses used in the animal study exceeded typical human environmental exposure, the experimental results further indicate that such grip strength reduction may be linked to muscle inflammation. Full article

Grokhovskyite, CuCrS₂, was observed in small sulfide inclusions (up to 50–80 µm) in Ni-rich iron (kamacite) of the Uakit iron meteorite (IIAB) in the Republic of Buryatia, Russia. The grain sizes of this mineral are usually less than 5 μm, and the biggest detected crystals are 10 × 5 μm in size. It is commonly associated with daubréelite, troilite, schreibersite, and, sometimes, with carlsbergite and uakitite. Within inclusions, the mineral forms elongated splintered crystals, or, rarely, needle-shaped grains in daubréelite. The grokhovskyite-containing associations in the Uakit meteorite seem to form due to high-temperature (>1000 °C) separation of Fe-Cr sulfide liquid, which is locally enriched in Cu, from Fe-Ni metal melt. Physical and optical properties of grokhovskyite are quite similar to those of synthetic CuCrS₂: yellow–brown and non-transparent phase with metallic luster; Mohs hardness ≈ 4; gray to light gray color with yellow tint in reflected light; weak to medium bireflectance, anisotropy, and pleochroism; density (calc.) = 4.559 g/cm³. Grokhovskyite is structurally related to the Cr-containing disulfide minerals with general formula Me⁺CrS₂ (where Me⁺ = Na, Cu, Ag), including caswellsilverite, NaCrS₂; schöllhornite, Na_0.3CrS₂·H₂O; and cronusite, Ca_0.2CrS₂·2H₂O. Structural data were obtained for one grokhovskyite crystal using the EBSD technique. Fitting of the EBSD patterns for a synthetic α-CuCrS₂ model (trigonal R3m; a = 3.4794(8) Å; c = 18.702(4) Å; V = 196.08(10) ų; Z = 3) resulted in the parameter MAD = 0.57–1.16° (good fit). Analytical data for grokhovskyite (n = 36, in wt.%) are as follows: Cu—32.97; Cr—27.65; Fe—3.69; Ni—0.16; S—35.71; Na, Zn, V, Mn, and Co—below detection limit (<0.005 wt.%). The empirical formula is (Cu_0.930Cr_0.952Fe_0.118Ni_0.005)_2.005S_1.995; however, different concentrations of Fe are indicated in two individual grains of grokhovskyite (0.09–0.17 apfu). Such variations may be explained by Fe incorporation in the grokhovskyite structure according to the scheme ^IVCu⁺ + ^VICr³⁺ → ^IVFe²⁺ + ^VIFe²⁺. The three main bands (near 110, 250, and 310 cm⁻¹), which are common of synthetic CuCrS₂, were observed in the Raman spectra of grokhovskyite. Full article

The gliding arc plasma technique (glidarc) was used for the precipitation and deposition of Mn or Fe oxides on zirconia fibers. Two types of fibers were used: commercial (Fib Zr(C)) and biomorphic (Fib Zr(B)) ZrO₂ fibers, the latter produced using cotton as a biotemplate. Both series of supported catalysts were characterized physicochemically and morphologically. Scanning Electron Microscopy (SEM) analyses showed that Fib Zr(B) largely retained the morphology of cotton. Fib Zr(B) presented the tetragonal phase (t-ZrO₂), while Fib Zr(C) exhibited the monoclinic phase (m-ZrO₂). Using X-ray Diffraction (XRD), the cryptomelane phase (K_xMn₈O₁₆) was identified only for Mn-Fib Zr(B). In the case of Fe-supported samples, the α-Fe₂O₃ phase appeared clearly in both biomorphic and commercial fibers. SEM and Transmission Electron Microscopy (TEM) images revealed that the precipitated iron oxides appeared to be better distributed than the manganese oxides, covering the outer surface of the fibrous supports more homogeneously. X-ray Photoelectron Spectroscopy (XPS) confirmed that Mn has an average oxidation state between 3+ and 4+, consistent with the cryptomelane phase detected by XRD. The synthesized supported systems were tested as catalysts in soot and CO oxidation, with the Mn-supported fibers proving to be more active than their Fe-containing counterparts in both reactions. Full article

Composite materials based on low-density polyethylene (LDPE) embedded with iron-manganese nanoparticles with compositions Fe_0.9Mn_0.1 and Fe_0.8Mn_0.2 were prepared and investigated. The newly created composites were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and Mössbauer spectroscopy. The composition, electronic, and atomic structure of the nanoparticles were established. The study confirms that the nanoparticles possess a ‘core-shell’ structure, the nature of which depends on the manganese content. The nanoparticles of Fe_0.8Mn_0.2 in LDPE exhibit a three-layered structure: a metallic α-Fe core is coated with an intermediate oxidized layer structurally close to Fe₂O₃, while the outermost shell consists of manganese oxide (Mn₂O₃). In contrast, nanoparticles with lower Mn content Fe_0.9Mn_0.1 show a predominantly fully oxidized structure. This structural evolution is consistent with thermodynamic principles, where manganese, having a higher oxide formation enthalpy, migrates to the surface. The core–shell architecture is promising for applications requiring stable magnetic components or tailored catalytic interfaces within a polymer matrix. Full article

The direct synthesis of long-chain α-olefins from syngas offers a strategically vital pathway for producing high-value chemicals from alternative carbon resources. However, achieving high selectivity toward C₅₊ olefins remains challenging due to competing paraffin formation and difficulties in precisely regulating chain growth kinetics. To mitigate these critical challenges, a series of Rh-promoted Co-Mn catalysts supported on SiO₂ were synthesized using a carbon-mediated impregnation strategy for the direct conversion of syngas to long-chain α-olefins (C₅₊). The introduction of Rh significantly enhanced both catalytic activity and C₅₊ olefin selectivity. The optimal 1.1 wt% Rh-loaded catalyst achieved 24.6% CO conversion and 46.0% total olefin selectivity, with 34.2% of the selectivity toward C₅₊ olefins, while maintaining low CH₄ (6.2%) and CO₂ (<1%) selectivity. Comprehensive characterization techniques, including XRD, H₂-TPR, XPS, and TEM/HAADF-STEM, revealed that the carbon-mediated method facilitated the formation of highly dispersed Co₃O₄ nanoparticles with abundant oxygen vacancies and strengthened the Co-MnO_x interface. Rh promotion modulated the cobalt speciation (Co⁰/Co²⁺), improved reducibility, and enhanced the metal-support interaction. This promoted chain growth and olefin desorption while suppressing over-hydrogenation. This study demonstrates the efficacy of Rh promotion and carbon mediation in designing high-performance Fischer-Tropsch catalysts for selective α-olefin synthesis, offering new insights into the design of efficient metal-oxide interfacial catalysts. Full article

Bee pollen is highly regarded for its nutritional and therapeutic properties, and Tunisia’s diverse ecosystems provide ideal conditions to produce high-quality bee pollen. The aim of this study was to characterize seven polyfloral bee pollen samples from major Tunisian regions, analysing their physicochemical and phytochemical parameters to evaluate compliance with national quality standards and their potential contribution to human nutrition. The nutritional and biochemical characterization of bee pollen samples was performed using standardized methods. Phenolic, flavonoid, and tannin contents were measured by colorimetric assays; carotenoids and chlorophylls spectrophotometrically; amino acids and sugars by HPLC; fatty acids by GC–MS; and minerals by atomic absorption spectroscopy. Amino acid levels were relatively constant between samples, but significant differences (p < 0.05) were noted, with concentrations ranging from 4.93 ± 0.15 mg·kg⁻¹ (K-O4) to 82.72 ± 2.36 mg·kg⁻¹ (O-O4). Tyrosine, aspartic acid, and glutamic acid were the dominant amino acids in both total and free forms, while threonine was identified as the relatively limiting amino acid. The proportion of total essential amino acids (TEAA) to total amino acids (TAA) met the nutritional recommendations set by the FAO. A total of 16 fatty acids were quantified in the seven BP samples, including nine saturated and six unsaturated fatty acids, with total content ranging from 0.26 g/100 g⁻¹ (T-03) to 37.06 g/100 g⁻¹ (G-03), which the primary fatty acids identified were α-linolenic acid, palmitic acid, and oleic acid. However, palmitoleic acid was detected in only two samples, in small amounts (0.34% and 0.46%). Essential minerals such as K, Ca, P, Mg, Zn, Fe, Mn, and Cu were present in significant amounts, playing a crucial role in both plant metabolism and human health Despite variations between samples, Tunisian bee pollen was overall evaluated as a valuable dietary supplement. Full article

Although Ru-based catalysts have been investigated in various oxidation systems, their application in sulfate radical-based AOPs, particularly as heterogeneous activators for acidic wastewater treatment, remains limited. Herein, Ru was incorporated into α-MnO₂ via lattice doping and surface loading to construct Ru_latt/α-MnO₂ and Ru_surf/α-MnO₂, and their PMS activation performance toward carbamazepine (CBZ) degradation was evaluated. Ru_latt/α-MnO₂ exhibited superior activity, achieving near-complete CBZ removal within minutes under acidic conditions. PMS dosage, catalyst loading, and pH affected the degradation efficiency, with acidic environments significantly enhancing PMS activation. Cl⁻ slightly promoted CBZ degradation, whereas HCO₃⁻ and natural organic matter inhibited it. Mechanistic analysis revealed that Ru activated PMS through a nonradical pathway, continuously generating ¹O₂ via a reversible Ru (II)/Ru (III)/Ru (IV) cycle, while the Mn (III)/Mn (IV) redox couple acted as an electron buffer to sustain Ru cycling and improve durability. The catalyst maintained high activity in complex water matrices, demonstrating strong potential for practical remediation of CBZ-contaminated acidic wastewater. Full article

Fe-Mn-Al-C lightweight steel is an alternative to traditional low-alloy structural steels. It is lightweight and can be used to reduce the weight of structures without increasing their density. However, in the marine environment, traditional low-alloy structural steels can be damaged by chloride ions, which shortens their service life. We do not yet understand how aluminum, an important alloying element in lightweight steel, affects the process of corrosion. In this study, we examined Fe-Mn-Al-C lightweight steels with different amounts of aluminum. We used full-immersion simulated marine corrosion tests and multi-dimensional characterization techniques, such as microstructure observation and electrochemical measurements, to explore the relationship between aluminum content and the steel’s corrosion rate, corrosion product structure, and corrosion resistance. The results showed that, compared with CS, the weight loss and rate of corrosion of steels that contain aluminum were a lot lower. While the corrosion rate of CS is approximately 0.068 g·h⁻¹·m⁻², that of 7Al steel is reduced to 0.050 g·h⁻¹·m⁻². The stable phases α-FeOOH and FeAl₂O₄ are formed in the corrosion products when Al is added. As the Al content increases, so does the relative content of these phases. Furthermore, FeAl₂O₄ acts as a nucleation site that refines corrosion product grains, reduces pores and cracks, and significantly improves the compactness of corrosion products. It also forms a dense inner rust layer that blocks the penetration of corrosive ions such as Cl⁻. This study confirmed that aluminum improves the corrosion resistance of steel synergistically by regulating the structure of the corrosion products, optimizing the phase composition, and improving the electrochemical properties. The optimal aluminum content for lightweight steel in marine environments is 7%, within a range of 5–9%. Full article

Element doping technology is widely recognized as an effective strategy for high-performance MnO₂-based cathode materials. While this approach improves the electronic and ionic conductivity of MnO₂, it is often accompanied by the introduction of oxygen vacancies. This synergistic effect poses challenges for precisely investigating the effect of doping elements on the d-electron configuration of the Mn site and establishing atomic-level structure-activity relationships for high-energy aqueous zinc-MnO₂ batteries. In this paper, the rational design of d-electron configurations in the Mn site has been achieved through simple Co doping in α-MnO₂ (CMO). Experimental results confirm that the introduction of Co can delocalize the d-electrons of the Mn site and increase the ratio of e_g (d_z² and d_x²_−y²) occupancy. Consequently, the charge transfer resistance, electrode polarization, and Zn²⁺ diffusion coefficient of the CMO-2 cathode have been greatly optimized. Thus, the as-prepared electrode delivers a high specific capacity of 287.4 mAh g⁻¹ at 1 A g⁻¹, with a capacity retention rate of 92.8% and a corresponding remaining capacity of 199.7 mAh g⁻¹ after 700 cycles. This study paves the road for the designation and construction of high-energy MnO₂ cathodes with optimized electronic structures for advanced aqueous zinc ion batteries. Full article

Photothermal catalysis has emerged as a promising approach for the efficient and cost-effective removal of volatile organic compounds (VOCs). Pt@MnO₂ catalysts have demonstrated excellent performance in the photothermal catalytic oxidation of VOCs. However, current research has predominantly focused on the interaction between Pt and MnO₂, while often overlooking the influence of the MnO₂ crystal phase. Therefore, in this study, we synthesized Pt supported on four crystal phases (α, β, γ, and δ) of MnO₂ and established the structure–activity relationships through performance evaluation and characterization. Among the prepared catalysts, Pt@Mn[δ] exhibited excellent performance and possessed outstanding stability. Crystal structure characterization revealed that the larger specific surface area and lower crystallinity of Pt@Mn[δ] exposed more active sites. XPS analysis indicated the transformation of Mn⁴⁺ to Mn³⁺ on Pt@Mn[δ], leading to the formation of oxygen vacancies. O₂-TPD and H₂-TPR further confirmed the activation of lattice oxygen and the promoted redox cycle of Pt@Mn[δ]. UV-Vis DRS and electrochemical measurements demonstrated that Pt@Mn[δ] exhibited the most pronounced visible-light absorption, the highest photocurrent density, the lowest charge transfer resistance and superior charge carrier mobility. TD-GC-MS analysis indicated that o-xylene underwent alkylation and isomerization, with subsequent oxidation following the Mars–van Krevelen (MvK) mechanism. Full article

Aqueous zinc-ion batteries (ZIBs) have emerged as a promising candidate for large-scale energy storage due to their inherent safety, low cost, and environmental friendliness. However, manganese dioxide (MnO₂)-based cathodes, which are widely studied for ZIBs owing to their high theoretical capacity and low cost, face severe capacity fading issues that hinder the commercialization of ZIBs. This performance degradation mainly stems from the weak van der Waals forces between MnO₂ layers leading to structural collapse during repeated Zn²⁺ insertion and extraction; it is also exacerbated by irreversible Mn dissolution via Mn³⁺ disproportionation that depletes active materials, and further aggravated by dynamic electrolyte pH fluctuations promoting insulating zinc hydroxide sulfate (ZHS) formation to block ion diffusion channels. To address these interconnected challenges, in this study, a synergistic strategy was developed combining crystal engineering and pH buffer regulation. We synthesized three MnO₂ polymorphs (α-, δ-, γ-MnO₂), identified δ-MnO₂ with flower-like microspheres as optimal, and introduced sodium dihydrogen phosphate (NaH₂PO₄) as a pH buffer (stabilizing pH at 2.8 ± 0.2). The modified electrolyte improved δ-MnO₂ wettability (contact angle of 17.8° in NaH₂PO₄-modified electrolyte vs. 26.1° in base electrolyte) and reduced charge transfer resistance (Rct = 78.17 Ω), enabling the optimized cathode to retain 117.25 mAh g⁻¹ (82.16% retention) after 2500 cycles at 1 A g⁻¹. This work provides an effective strategy for stable MnO₂-based ZIBs, promoting their application in renewable energy storage. Full article