Search Results (378)

Due to the feeding system (high-concentrate diet) during the early lactation stage, ruminal pH in dairy cows follows a diurnal pattern and can remain below the critical level of 5.5 for extended periods of the day. This study aimed to evaluate the effect of low ruminal pH on blood concentrations of certain macrominerals, trace minerals, and fat-soluble vitamins and on the oxidative status of dairy cows during the first half of lactation. Fifty-three randomly selected lactating Holstein cows were used; blood and ruminal fluid samples were collected from all cows on days 30, 90 and 150 of lactation. Blood samples were obtained via coccygeal venipuncture, while the ruminal fluid was obtained by rumenocentesis and the pH was measured immediately after collection. Using a threshold pH of 5.5, samples were classified as normal (pH > 5.5) or low pH (pH ≤ 5.5). Serum concentrations of Ca, Mg, K, Cr, Mn, Zn, Se, and vitamins A, D3, E, and K were not significantly affected by ruminal pH, either by days in milk or by their interaction (p > 0.05). Plasma malondialdehyde and reduced glutathione followed the same trend (p > 0.05). Copper concentration was significantly higher (p < 0.05), and Fe concentration tended to be higher in cows with low pH compared to those with normal pH (p = 0.052). On day 150 of lactation, Cu, Fe, and Co concentrations were significantly higher in low-pH cows compared to normal-pH cows (p < 0.05). Low ruminal pH is associated with significant changes in serum concentrations of copper, iron, and cobalt but has no significant effect on the oxidative status of the animals or on the serum concentrations of the macro elements and fat-soluble vitamins studied. Full article

Graphene quantum dots (GQDs) obtained by microwave-induced pyrolysis of glutamic acid and triethylenetetramine (trien) are fairly stable, emissive, water-soluble, and positively charged nano-systems able to interact with negatively charged meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS₄). The stoichiometric control during the preparation affords a supramolecular adduct, GQDs@TPPS₄, that exhibits a double fluorescence emission from both the GQDs and the TPPS₄ fluorophores. These supramolecular aggregates have an overall negative charge that is responsible for the condensation of cations in the nearby aqueous layer, and a three-fold acceleration of the metalation rates of Cu²⁺ ions has been observed with respect to the parent porphyrin. Addition of various metal ions leads to some changes in the UV/Vis spectra and has a different impact on the fluorescence emission of GQDs and TPPS₄. The quenching efficiency of the TPPS₄ emission follows the order Cu²⁺ > Hg²⁺ > Cd²⁺ > Pb²⁺ ~ Zn²⁺ ~ Co²⁺ ~ Ni²⁺ > Mn²⁺ ~ Cr³⁺ >> Mg²⁺ ~ Ca²⁺ ~ Ba²⁺, and it has been related to literature data and to the sitting-atop mechanism that large transition metal ions (e.g., Hg²⁺ and Cd²⁺) exhibit in their interaction with the macrocyclic nitrogen atoms of the porphyrin, inducing distortion and accelerating the insertion of smaller metal ions, such as Zn²⁺. For the most relevant metal ions, emission quenching of the porphyrin evidences a linear behavior in the micromolar range, with the emission of the GQDs being moderately affected through a filter effect. Deliberate pollution of the samples with Zn²⁺ reveals the ability of the GQDs@TPPS₄ adduct to detect sensitively Cu²⁺, Hg^2+, and Cd²⁺ ions. Full article

Weathering steel (WS) is widely used in bridge construction due to its high corrosion resistance, durability, and low maintenance requirements. This paper reviews the performance of WS bridges in Canadian climates, focusing on the formation of protective patina, influencing factors, and long-term maintenance strategies. The protective patina, composed of stable iron oxyhydroxides, develops over time under favorable wet–dry cycles but can be disrupted by environmental aggressors such as chlorides, sulfur dioxide, and prolonged moisture exposure. Key alloying elements like Cu, Cr, Ni, and Nb enhance corrosion resistance, while design considerations—such as drainage optimization and avoidance of crevices—are critical for performance. The study highlights the vulnerability of WS bridges to microenvironments, including de-icing salt exposure, coastal humidity, and debris accumulation. Regular inspections and maintenance, such as debris removal, drainage system upkeep, and targeted cleaning, are essential to mitigate corrosion risks. Climate change exacerbates challenges, with rising temperatures, altered precipitation patterns, and ocean acidification accelerating corrosion in coastal regions. Future research directions include optimizing WS compositions with advanced alloys (e.g., rare earth elements) and integrating climate-resilient design practices. This review highlights the need for a holistic approach combining material science, proactive maintenance, and adaptive design to ensure the longevity of WS bridges in evolving environmental conditions. Full article

Capsella bursa-pastoris (L.) Medik (C. bursa-pastoris) is an underexplored medicinal herb and bioindicator of potentially toxic elements (PTEs). Its broad traditional utilization combined with its high capacity for PTE accumulation may endanger human health. Herein, we investigated the concentrations and mobility of PTEs (Ba, Co, Cr, Cu, Fe, Mn, Ni, Sr, and Zn) in the urban soil–C. bursa-pastoris system and comprehensively assessed potential health risks associated with exposure to contaminated soils, plant and herbal extracts. Cu, Zn, Sr, and Mn were the most abundant in soils and predominantly phytoavailable. The calculated values of the geo-accumulation index (I_geo) indicated moderate to heavy Cu, Zn, and Sr contamination in the soil. C. bursa-pastoris demonstrated two strategies for PTEs—the exclusion of Ba, Cr, Mn, and Sr, and the accumulation of Cu, Ni, Co, and Fe. Principal Component Analysis (PCA) classified samples from four cities based on the PTE levels in soils, plants, and herbal extracts. Although plant tissues contained elevated levels of PTEs, the estimated daily intake (EDI), target hazard quotient (THQ), and lifetime carcinogenic risk (LCR) demonstrated no significant health risks from consuming C. bursa-pastoris and its extracts. The obtained results indicated the higher sensitivity of children to the hazardous effects of PTEs compared to adults. Extensive risk assessments of polluted soils and inhabiting plants are crucial in PTE monitoring. This study underscored its importance and delivered new insights into the contamination of medicinal herbs, aiming to contribute to implementing safety policies in public health protection. Full article

This study investigates the emission characteristics and environmental impacts of pollutants from bagasse-fired biomass boilers through the integrated field monitoring of two sugarcane processing plants in Guangxi, China. Comprehensive analyses of flue gas components, including PM_2.5, NOx, CO, heavy metals, VOCs, HCl, and HF, revealed distinct physicochemical and emission profiles. Bagasse exhibited lower C, H, and S content but higher moisture (47~53%) and O (24~30%) levels compared to coal, reducing the calorific values (8.93~11.89 MJ/kg). Particulate matter removal efficiency exceeded 98% (water film dust collector) and 95% (bag filter), while NOx removal varied (10~56%) due to water solubility differences. Heavy metals (Cu, Cr, Ni, Pb) in fuel migrated to fly ash and flue gas, with Hg and Mn showing notable volatility. VOC speciation identified oxygenated compounds (OVOCs, 87%) as dominant in small boilers, while aromatics (60%) and alkenes (34%) prevailed in larger systems. Ozone formation potential (OFP: 3.34~4.39 mg/m³) and secondary organic aerosol formation potential (SOAFP: 0.33~1.9 mg/m³) highlighted aromatic hydrocarbons (e.g., benzene, xylene) as critical contributors to secondary pollution. Despite compliance with current emission standards (e.g., PM < 20 mg/m³), elevated CO (>1000 mg/m³) in large boilers indicated incomplete combustion. This work underscores the necessity of tailored control strategies for OVOCs, aromatics, and heavy metals, advocating for stricter fuel quality and clear emission standards to align biomass energy utilization with environmental sustainability goals. Full article

High-entropy alloys are known for their promising mechanical properties, wear and corrosion resistance, which are maintained across a wide range of temperatures. In this study, a CoCrFeNiCu-based high-entropy alloy, distinguished from conventional CoCrFeNi systems by the addition of Cu, which is known to enhance toughness and wear resistance, was investigated to better understand the effects of compositional modification on processability and performance. The influence of key process parameters, specifically laser power and scan speed, on the processability of CoCrFeNiCu-based high-entropy alloys produced by laser powder bed fusion additive manufacturing was investigated, with a focus of low laser power, which is critical for minimizing defects and improving the resulting microstructure and mechanical performance. The printed sample density gradually increases with higher volumetric energy density, achieving densities exceeding 99.0%. However, at higher energy densities, the samples exhibit susceptibility to hot cracking, an issue that cannot be mitigated by adjusting the process parameters. Mechanical properties under optimized parameters were further evaluated using Charpy impact and (in situ) tensile tests. These evaluations were supplemented by in situ tensile experiments conducted within a scanning electron microscope to gain insights into the behavior of defects, such as hot cracks, during tensile testing. Despite the sensitivity to hot cracking, the samples exhibited a respectable ultimate tensile strength of 662 MPa, comparable to fine-grained steels like S500MC (070XLK). These findings underscore the potential of CoCrFeNiCu-based high-entropy alloys for advanced applications. However, they also highlight the necessity for developing strategies to ensure stable and reliable processing methods that can mitigate the susceptibility to hot cracking. Full article

The increasing discharge of nutrient and metal-laden effluents into saline environments demands sustainable remediation strategies. This study evaluated the phytoremediation potential of Salicornia brachiata, a halophytic plant, under hydroponic conditions using varying concentrations of three macronutrients—nitrate (NO₃⁻), phosphate (PO₄³⁻), and calcium (Ca²⁺)—and three heavy metals—lead (Pb²⁺), chromium (Cr⁶⁺), and copper (Cu²⁺). The plant exhibited high removal efficiencies across all treatments, with Pb²⁺ and Cr⁶⁺ reaching nearly 99% removal within two days, while macronutrient removal showed a steady, time-dependent increase over the 14-day period. Several biochemical parameters, including proline content and antioxidant enzyme activities (catalase, superoxide dismutase, peroxidase, polyphenol oxidase), were significantly affected by treatments, with most showing dose-dependent responses to heavy metal exposure, indicating strong biochemical resilience. Fourier transform infrared spectroscopy revealed pollutant-specific structural shifts and identified –OH, –NH, and –COO⁻ groups as key binding sites. The study quantifies the removal efficiency of S. brachiata for both nutrients and metals and provides mechanistic insight into its ionic stress response and binding pathways. These findings establish S. brachiata as a viable candidate for integrated phytoremediation in saline, contaminated water systems. Full article

The ongoing miniaturization of semiconductor devices necessitates continuous advancements in lithographic processes, which are critical for high-precision circuit formation. To prevent substrate damage during the etching step, a spin-on hardmask (SOH) layer is often introduced between the photoresist (PR) and the substrate. However, residual metal ions in SOH solutions can adversely affect integrated circuit performance, underscoring the need for efficient and chemically compatible removal strategies. This study investigates the adsorption of metal ions (Al³⁺, Cr³⁺, Cu²⁺, Fe³⁺, Ni²⁺, and Ti⁴⁺) from SOH solutions using mesoporous silica materials—MCM-41 and SBA-15—functionalized with various groups (–OH, –NH₂, –SH, and –CH₃). Adsorption performance was evaluated under solvent-only, monomer-containing, and polymer-containing conditions. Among the tested materials, amine-functionalized mesoporous silica exhibited the highest adsorption efficiency, with SBA-15-NH₂ showing relatively effective and uniform performance in polymer-containing systems. Isotherm analysis supported a monolayer chemical adsorption mechanism, suggesting the significance of surface functional groups in the adsorption process. These findings demonstrate the potential of functionalized mesoporous silica as a promising candidate for trace metal ion removal in semiconductor manufacturing, offering enhanced yield and improved process reliability. Full article

With the implementation of the ISO 8217-2024 marine fuel standard, the use of high-concentration biofuels in ships has become viable. However, relatively few studies have been conducted on the effects of biofuels on cylinder lubrication performance in low-speed, two-stroke marine diesel engines. In this study, catering waste oil was blended with 180 cSt low-sulfur fuel oil (LSFO) to prepare biofuels with volume fractions of 24% (B24) and 50% (B50). These biofuels were evaluated in a MAN marine diesel engine under load conditions of 25%, 50%, 75%, and 90%. The experimental results showed that, at the same engine load, the use of B50 biofuel led to lower kinematic viscosity and oxidation degree of the cylinder residual oil, but higher total base number (TBN), nitration level, PQ index, and concentrations of wear elements (Fe, Cu, Cr, Mo). These results indicate that the wear of the cylinder liner–piston ring interface was more severe when using B50 biofuel than when using B24 biofuel. For the same type of fuel, as the engine load increased, the kinematic viscosity and TBN of the residual oil decreased, while the PQ index and the concentrations of Fe, Cu, Cr, and Mo increased, reflecting the aggravated wear severity. Ferrographic analysis further revealed that ferromagnetic wear particles in the oil mainly consisted of normal wear debris. When using B50 biodiesel, a small amount of fatigue wear particles were detected. These findings offer crucial insights for optimizing biofuel utilization and improving cylinder lubrication systems in marine engines. Full article

The lacustrine mudstones and shales of the Triassic Yanchang Formation in the Ordos Basin serve as critical hydrocarbon source rocks. However, previous studies predominantly focus on individual lithologies, with comparative investigations into the sedimentary environments of dark mudstones and black shales remaining relatively limited. The study systematically compares sedimentary environment parameters (e.g., paleoclimate, paleosalinity, paleoredox conditions, paleowater depth, and paleoproductivity characteristics) between mudstones and shales, and how these distinct environmental factors governed the differential enrichment mechanisms of organic matter within the depositional aquatic system has been elucidated. Geochemical proxies (e.g., CIA, Sr/Cu, Rb/Sr, Sr/Ba, V/Ni, U/Th, V/Cr, Rb/Zr, P/Ti, Cu/Ti) reveal marked contrasts: In comparison with the Chang 7 and Chang 8 dark mudstones, the Chang 7 black shales exhibit (1) warmer–humid paleoclimatic regimes, (2) higher paleosalinity, (3) intensely anoxic conditions, (4) deeper paleowater depth, and (5) elevated paleoproductivity. These environmental divergences directly govern the significant total organic carbon content disparity between black shales and dark mudstones. Organic enrichment in the Chang 7 dark mudstones and black shales is primarily controlled by paleoproductivity and paleoredox conditions, with secondary influences from paleoclimate and paleowater depth. Based on the above studies, this research established a differential organic matter enrichment model. This research is of significant importance for guiding oil and gas exploration and development in the Ordos Basin. Full article

This study investigates the influence of Si content (x = 0, 0.1, 0.3, 0.5) on the microstructure, mechanical properties, and wear behavior of FeNiCrAl_0.7Cu_0.3Si_x high-entropy alloys. With increasing silicon content, the microstructure evolves from a dendritic morphology in the silicon-free FeNiCrAl_0.7Cu_0.3 alloy to a transitional structure in the FeNiCrAl_0.7Cu_0.3Si_0.1 alloy that retains dendritic features; then to a chrysanthemum-like morphology in the FeNiCrAl_0.7Cu_0.3Si_0.3 alloy, and finally to island-like grains in the FeNiCrAl_0.7Cu_0.3Si_0.5 alloy. This evolution is accompanied by a phase transition from an Fe and Cr-rich body-centered cubic phase to an Al and Ni-rich body-centered cubic phase, with silicon showing a tendency to segregate alongside aluminum and nickel. The microhardness increases from 498.2 ± 15.0 HV for the FeNiCrAl_0.7Cu_0.3 alloy, to 502.7 ± 32.7 HV for FeNiCrAl_0.7Cu_0.3Si_0.1, 577.3 ± 24.5 HV for FeNiCrAl_0.7Cu_0.3Si_0.3, and 863.2 ± 23.5 HV for FeNiCrAl_0.7Cu_0.3Si_0.5. The average friction coefficients are 0.571, 0.551, 0.524, and 0.468, respectively. The wear mass decreases from 1.31 mg in the FeNiCrAl_0.7Cu_0.3 alloy to 1.28 mg, 1.11 mg, and 0.78 mg in the FeNiCrAl_0.7Cu_0.3Si_0.1, FeNiCrAl_0.7Cu_0.3Si_0.3, and FeNiCrAl_0.7Cu_0.3Si_0.5 samples, respectively. These trends are consistent with the increase in microhardness, supporting the inverse relationship between hardness and wear. As the silicon content increases, the dominant wear mechanism changes from abrasive wear to adhesive wear, with the high-silicon alloy exhibiting lamellar debris on the worn surface. These findings confirm that silicon addition enhances microstructural refinement, mechanical strength, and wear resistance of the alloy system. Full article

Leachates generated from the degradation of green waste and biosolids from urban wastewater treatment plants (WWTPs) pose significant environmental concerns due to high concentrations of organic pollutants and heavy metals. This study proposes a hybrid treatment strategy combining electrocoagulation (EC) and UVC-activated TiO₂ photocatalysis to remediate leachates produced in laboratory-scale biocells. Initial characterization revealed critical pollutant levels: COD (1373 mg/L), BOD₅ (378 mg/L), total phosphorus (90 mg/L), ammoniacal nitrogen (201 mg/L), and metals such as Ni, Pb, and Mn levels all exceeding those set out in the Ecuadorian discharge regulations. Optimized EC achieved removal efficiencies of 62.6% for COD, 44.4% for BOD₅, 89.8% for phosphorus, and 86.2% for color. However, residual contamination necessitated a subsequent photocatalytic step. Suspended TiO₂ under UVC irradiation removed up to 81.8% of the remaining COD, 88.7% of the ammoniacal nitrogen, and 94.4% of the phosphorus. Levels of heavy metals such as Zn, Fe, Pb, Mn, and Cu were reduced by over 80%, while Cr⁶⁺ was nearly eliminated. SEM–EDS analysis confirmed successful TiO₂ immobilization on sand substrates, revealing a rough, porous morphology conducive to catalyst adhesion; however, heterogeneous titanium distribution suggests the need for improved coating uniformity. These findings confirm the potential of the EC–TiO₂/UVC hybrid system as an effective and scalable approach for treating complex biocell leachates with reduced chemical consumption. Full article

This study investigates the interfacial reactions of FeCoNiCr and FeCoNiMn medium-entropy alloys (MEAs) with Sn and Sn-3Ag-0.5Cu (SAC305) solders at 250 °C. The evolution of interfacial microstructures is analyzed over various aging periods. For comparison, the FeCoNiCrMn high-entropy alloy (HEA) is also examined. In the Sn/FeCoNiCr system, a faceted (Fe,Cr,Co)Sn₂ layer initially forms at the interface. Upon aging, the significant spalling of large (Fe,Cr,Co)Sn₂ particulates into the solder matrix occurs. Additionally, an extremely large, plate-like (Co,Ni)Sn₄ phase forms at a later stage. In contrast, the Sn/FeCoNiMn reaction produces a finer-grained (Fe,Co,Mn)Sn₂ phase dispersed in the solder, accompanied by the formation of the large (Co,Ni)Sn₄ phase. This observation suggests that Mn promotes the formation of finer intermetallic compounds (IMCs), while Cr facilitates the spalling of larger IMC particulates. The Sn/FeCoNiCrMn system exhibits stable interfacial behavior, with the (Fe,Cr,Co)Sn₂ layer showing no significant changes over time. The interfacial behavior and microstructure are primarily governed by the dissolution of the constituent elements and composition ratio of the HEAs, as well as their interactions with Sn. Similar trends are observed in the SAC305 solder reactions, where a larger amount of fine (Fe,Co,Cu)Sn₂ particles spall from the interface. This behavior is likely attributed to Cu doping, which enhances nucleation and stabilizes the IMC phases, promoting the formation of finer particles. The wettability of SAC305 solder on MEA/HEA substrates was further evaluated by contact angle measurements. These findings suggest that the presence of Mn in the substrate enhances the wettability of the solder. Full article

Plants serve as vital components of ecosystems, with their contamination status acting as sensitive indicators of environmental pollution. Therefore, the precise assessment of plant heavy metal contamination and source identification are crucial for regional ecological conservation and sustainable development. This study investigated heavy metal pollution in four characteristic plant species (Anabasis aphylla L., Alhagi camelorum Fisch., Reaumuria songonica (PalL)Maxim., and Haloxylon ammodendron (C. A. Mey.) Bunge.) within the Kalamaili Mountain Nature Reserve, employing comprehensive methodologies including pollution indices, bioconcentration factors (BCFs), absolute principal component score–multiple linear regression (APCS-MLR), and the random forest model (RF). The key findings revealed the following: The soil exhibited severe Cd and Hg contamination. The plant Cr concentrations exceeded standard limits by 31.89 to 147 fold. The Pb, Hg, and As content in plants showed significant differences. The plants displayed differential metal enrichment capacities, ranked as Cr (BCF = 3.28) > Hg (1.22) > Cd (0.92) > Cu (0.25) > Zn (0.15) > Pb (0.125) > As (0.125), highlighting Cr, Hg, and Cd as priority ecological hazards. Complex interactions were observed, with Reaumuria songonica (PalL)Maxim. showing strong Cd soil–plant correlation (r = 0.78), whereas Alhagi camelorum Fisch. demonstrated negative associations (Cd: r = −0.21). APCS-MLR identified mining/smelting as primary contributors to Cd (63.49%), Zn (55.66%), and Cr (45.51%), while transportation dominated Pb emissions (72.92%). Mercury pollution originated from mixed sources (56.18%), likely involving atmospheric deposition, and RF modeling corroborated these patterns, confirming industrial and transportation synergies for Cd, Zn, Cr, Cu, Hg, and As, with Pb predominantly linked to vehicular emissions. This multidisciplinary approach provides scientific evidence for establishing heavy metal monitoring systems and formulating targeted remediation strategies in arid ecologically fragile regions. Full article

Rapid land-use changes have significantly changed the occurrence of heavy metals (HMs) in tropical watershed systems. However, the influence of land-use patterns on the spatial and temporal distribution of HMs in tropical river systems remains poorly understood. This study aims to explore the relationship between land-use types and HM pollution in the China’s largest tropical watershed, the Nandu River. Eight heavy metals (Cd, Pb, Cr, Cu, Zn, As, Hg, and Sb) in the surface water were monitored across river, estuary, and nearshore zones during wet and dry seasons. Our findings show a higher total concentration of eight heavy metals (ΣHMs) in the wet season (30.52 μg/L) compared to the dry season (21.53 μg/L). In the wet season, ΣHM concentrations followed the order: estuary (70.96 μg/L) > basin (31.03 μg/L) > nearshore (8.07 μg/L). In the dry season, it was basin (31.56 μg/L) > estuary (23.26 μg/L) > nearshore (7.49 μg/L). Land-use patterns had higher interpretation rates for HM distribution in the dry season (65.8–73.0%) compared to the wet season (31.0–42.4%). The 2000 m buffer zone had a greater impact on HM distribution than the 500 m and 1000 m zones. Agricultural land and construction areas were the primary contributors to HM pollution in the dry and wet seasons, respectively. Noteworthy, in the river basin, chromium (Cr) presented carcinogenic risks to both children and adults through ingestion in both seasons and arsenic (As) posed a risk to children in the dry season. This study provides valuable insights for the sustainable management of land use and improving river water quality by highlighting the relationship between land use and HM contamination in tropical river ecosystems. Full article