Search Results (295)

Petrological knowledge on weathering processes controlling the mobility of chemical elements is still limited in the dry tropical zone of Cameroon. This study aims to investigate the mobility of major and trace elements during rhyolite weathering and soil formation in Mobono by understanding the mineralogical and elemental vertical variation. The studied soil was classified as Cambisols containing mainly quartz, K-feldspar, plagioclase, smectite, kaolinite, illite, calcite, lepidocrocite, goethite, sepiolite, and interstratified clay minerals. pH values ranging between 6.11 and 8.77 indicated that hydrolysis, superimposed on oxidation and carbonation, is the main process responsible for the formation of secondary minerals, leading to the formation of iron oxides and calcite. The bedrock was mainly constituted of SiO₂, Al₂O₃, Na₂O, Fe₂O₃, Ba, Zr, Sr, Y, Ga, and Rb. Ce and Eu anomalies, and chondrite-normalized La/Yb ratios were 0.98, 0.67, and 2.86, respectively. SiO₂, Al₂O₃, Fe₂O₃, Na₂O, and K₂O were major elements in soil horizons. Trace elements revealed high levels of Ba (385 to 1320 mg kg⁻¹), Zr (158 to 429 mg kg⁻¹), Zn (61 to 151 mg kg⁻¹), Sr (62 to 243 mg kg⁻¹), Y (55 to 81 mg kg⁻¹), Rb (1102 to 58 mg kg⁻¹), and Ga (17.70 to 35 mg kg⁻¹). LREEs were more abundant than HREEs, with LREE/HREE ratio ranging between 2.60 and 6.24. Ce and Eu anomalies ranged from 1.08 to 1.21 and 0.58 to 1.24 respectively. The rhyolite-normalized La/Yb ratios varied between 0.56 and 0.96. Mass balance revealed the depletion of Si, Ca, Na, Mn, Sr, Ta, W, U, La, Ce, Pr, Nd, Sm, Gd and Lu, and the accumulation of Al, Fe, K, Mg, P, Sc, V, Co, Ni, Cu, Zn, Ga, Ge, Rb, Y, Zr, Nb, Cs, Ba, Hf, Pb, Th, Eu, Tb, Dy, Ho, Er, Tm and Yb during weathering along the soil profile. Full article

The resource utilization potential and environmental impact of fly ash from municipal solid waste incinerators (MSWIs) have attracted wide attention. In this study, four MSWIs in Hangzhou, Zhejiang Province were selected to systematically evaluate the effects of different incinerator types and flue gas deacidification processes on fly ash’s oxide and heavy metal components and their temporal changes as well as conduct risk assessment. The results showed that the contents of MgO, Al₂O₃, SiO₂, and Fe₂O₃ in the grate furnace fly ash were significantly lower than those in the fluidized bed fly ash, but the compressive strength of its fly ash was high. Chemicals added during the flue gas deacidification process such as CaO and NaHCO₃ significantly affected the contents of CaO and Na₂O. In addition, heavy metals such as Cu, Mn, Cr, and Ni were mainly distributed in the fluidized bed fly ash, while heavy metals such as Pb and Cd were mainly collected in the grate furnace fly ash. The concentrations of various components in the fly ash fluctuated but were not significant under different time dimensions. Risk assessment indicated that heavy metals such as Cd, Pb, and Sb posed a high risk. This study is expected to provide theoretical support for the safe management and resource utilization of fly ash. 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

Milk powder is a key nutritional alternative to breastfeeding, but its thermal properties, which vary with temperature, can affect its quality and shelf life. However, there is little information about the physical and chemical properties of powdered milk in several countries. This dataset contains the result of an analysis of the aflatoxins, macroelement and microelement concentrations, oxidative stability, and fatty acid profile of infant formula milk powder. The concentrations of Al, As, Ba, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Se, V, and Zn in digested powdered milk samples were quantified through inductively coupled plasma optical emission spectrometry (ICP OES). Thermogravimetry (TG) and differential scanning calorimetry (DSC) were used to estimate the oxidative stability of infant formula milk powder, while the methyl esters of the fatty acids were analyzed by gas chromatography. Most milk samples showed significant concentrations of As (0.5583–1.3101 mg/kg) and Pb (0.2588–0.0847 mg/kg). The concentrations of aflatoxins G2 and B2 are below the limits established by Brazilian regulatory agencies. The thermal degradation behavior of the samples is not the same due to their fatty acid compositions. The data presented may be useful in identifying compounds present in infant milk powder used as a substitute for breast milk and understanding the mechanism of thermal stability and degradation, ensuring food safety for those who consume them. Full article

Carbon dioxide (CO₂) and hydrogen sulfide (H₂S) as harmful gases are always associated with methane (CH₄) in natural gas, biogas, and landfill gas. Given that chemisorption and physisorption are the key gas separation technologies in industry, selecting appropriate adsorbents is crucial to eliminate these harmful gases. The adsorption of CH₄, CO₂, and H₂S has been studied based on the density functional theory (DFT) in this work to evaluate the feasibility of transition metal (M = Mn, Fe, Co, Ni, Cu, Mo) porphyrin-like moieties embedded in graphene sheets (MN₄-GPs) as adsorbents. It was found that the interactions between gas molecules and MN₄-GPs (M = Mn, Fe, Co, Ni, Cu, Mo) are different. The weaker interactions between CH₄ and MN₄-GPs (M = Co, Ni, Cu, Mo) than those between CO₂ and MN₄-GPs or between H₂S and MN₄-GPs are beneficial to the separation of CH₄ from CO₂ and H₂S. The maximum difference in the interactions between gas molecules and MoN₄-GPs means that MoN₄-GPs have the greatest potential to become adsorbents. The different interfacial interactions are related to the amount of charge transfer, which could promote the formation of bonds between gas molecules and MN₄-GPs to effectively enhance the interfacial interactions. Full article

We studied the influence of annealing on the magnetic properties and microstructure of ultrathin (metallic nucleus diameter ≈ 5 μm, total diameter ≈ 19 μm) Heusler-type NiMnGa glass-coated microwires prepared using the Taylor–Ulitovsky method. The as-prepared NiMnGa microwires exhibit unexpectedly strong magnetic anisotropy, characterized by a coercivity exceeding 3 kOe at room temperature. Furthermore, their Curie temperature (T_c) lies above room temperature. Additionally, a spontaneous exchange bias of approximately 120 Oe is observed in the as-prepared sample at 100 K. Annealing the microwires leads to a decrease in coercivity, spontaneous exchange bias, and T_c values. Notably, the annealing process shifts the T_c of the samples closer to room temperature, making them more suitable for magnetic solid-state refrigeration applications. Moreover, the hysteresis observed in the temperature dependence of magnetization for the samples annealed for 1 h and 2 h, along with the magnetic softening observed at around 260 K, is attributed to a first-order phase transformation. The observed changes are discussed in the context of internal stress relaxation after annealing, the nanocrystalline structure of both the as-prepared and annealed samples, the recrystallization process, and the magnetic ordering of phases identified in the as-prepared sample and those appearing during recrystallization. The glass coating on microwires offers benefits like better flexibility and resistance to damage and corrosion. However, it is important to recognize that this coating can substantially alter the microwires’ magnetic characteristics. Consequently, precise control over the annealing process is vital to obtain the specific martensitic transformation needed. Full article

Particulate matter (PM) has been associated with various health issues. However, the most hazardous constituents of fine particles remain unclear, particularly in Asia where the chemical compositions are highly diverse and understudied. This study investigated the concentration and health risks of particulate-bound polycyclic aromatic hydrocarbons (PAHs) and heavy metals in the indoor air of religious spaces in Bangkok, Thailand. Air samples were collected from four religious sites during periods of high activity using a six-stage NanoSampler to capture particle sizes ranging from <0.1 to >10 µm. Chemical analyses were conducted using gas chromatography-mass spectrometry (GC-MS/MS) for PAHs and inductively coupled plasma-mass spectrometry (ICP-MS) for heavy metals. The results revealed significantly elevated concentrations of PM2.5, PAHs (notably benzo[a]anthracene (BaA), chrysene (CHR), and fluoranthene (FLU)), and heavy metals (particularly Mn, Ni, and Cu). Health risk assessments indicated that both the incremental lifetime cancer risk (ILCR) and hazard quotient (HQ) values for several pollutants exceeded the U.S. EPA safety thresholds, suggesting serious cancer and non-cancer health risks for workers exposed to these environments over prolonged periods. This study highlights incense burning as a dominant source of toxic indoor air pollutants and underscores the urgent need for mitigation strategies to reduce occupational exposure in religious buildings. Full article

Research on two dimensional (2D) antiferromagnetic materials and heterobilayers is gaining prominence in spintronics. This study focuses on MPS₃ monolayers and their van der Waals heterobilayers with GaN monolayers. We systematically investigated the structural stability, electronic properties, and magnetic characteristics of MPS₃ (M = Mn, Fe, and Ni) monolayers via first-principles calculations, and explored their potential applications in optoelectronics and spintronics. Through phonon spectrum analysis, the dynamic stability of MPS₃ monolayers was confirmed, and their bond lengths, charge distributions, and wide-bandgap semiconductor properties were analyzed in detail. In addition, the potential applications of MPS₃ monolayers in UV detection were explored. Upon constructing the MPS₃/GaN heterobilayer structure, a significant reduction in the bandgap was observed, thereby expanding its potential applications in the visible light spectrum. The intrinsic antiferromagnetic nature of MPS₃ monolayers was confirmed through calculations, with the magnetic moments of the magnetic atoms M being 4.560, 3.672, and 1.517, respectively. Moreover, the heterobilayer structures further enhanced the magnetic moments of these elements. The magnetic properties of MPS₃ monolayers were further analyzed using spin-orbit coupling (SOC), confirming their magnetic anisotropy. These results provide a theoretical basis for the design of novel two-dimensional spintronic and optoelectronic devices based on MPS₃. Full article

Magnetic shape memory alloys have attracted considerable attention due to their multifunctional properties. Among these materials, Ni-Mn-Ga alloys are distinguished by their ability to achieve up to 10% strain when exposed to a magnetic field, a characteristic predominantly observed in single-crystal samples. Consequently, it is essential to develop nanomaterials with a crystal structure closely resembling that of a single crystal. In this study, an epitaxial Ni-Mn-Ga thin film was fabricated using Pulsed Laser Deposition on an Al₂O₃ $\left(11\overline{2}0\right)$ single-crystal substrate. The crystal structure was characterised through X-ray diffraction methodologies, such as symmetrical $2\theta -\omega$ scans, pole figures, and reciprocal space maps. The results indicated that the sample was mainly in a slightly distorted cubic austenite phase, and some incipient martensite phase also appeared. A detailed microstructural analysis, performed by transmission electron microscopy, confirmed that certain regions of the sample exhibited an incipient transformation to the martensite phase. Regions closer to the substrate retained the austenite phase, suggesting that the constraint imposed by the substrate inhibits the phase transition. These results indicate that it is possible to grow high crystalline quality thin films of Ni-Mn-Ga by Pulsed Laser Deposition. Full article

NiTi and NiMnGa stand out as prime thermal and magnetic shape memory alloys (SMAs), possessing a superior shape memory effect (SME) and superelasticity (SE). These alloys have crucial current and potential future applications across industries. Additive manufacturing (AM) offers a transformative approach to fabricating these materials into complex geometries; however, the quest to create integral additively manufactured structures with reliable thermal or magnetic shape memory properties remains a recent and fast-emerging research frontier. This article provides a comprehensive review on (i) the intricate principles giving rise to the thermal SME and SE in NiTi, and the magnetic SME in NiMnGa alloys, emphasising their specific relevance in the realm of AM, and (ii) the latest developments, recent findings, and ongoing challenges in the AM of NiTi- and NiMnGa-based SMAs, including their functional lattice structures. Based on this review, for the first time, novel, empirically derived AM process design maps tailored to maximise SME and SE in laser powder bed fusion- and directed-energy deposition-processed NiTi structures are proposed. Similarly, promising avenues to resolve the key challenges regarding the AM of NiMnGa magnetic SMAs are suggested. This article concludes by outlining the most promising future research directions shaping the trajectory of AM of these SMAs. Full article

In this article, the results of full-scale experiments on the addition of a sodium sulfide to the ${\mathrm{CaCO}}_3$ slurry circuit in a wet flue gas desulfurization (WFGD) plant are presented. Tests are performed on two comparable WFGD installations (spray tower, 4 spraying levels and two stage gypsum de-watering by hydrocyclones and vacuum belt filter) which allows the investigation of the influence of lignite composition (lignite mined in Poland and the Czech Republic are compared) on the reduction in mercury emission. Additionally, the efficiency of precipitation of metals from the slurry (Hg, Zn, Pb, Cd, Cr, Cu, Ni, Fe, Se, and Mn) is investigated as the result of sulfide addition. For both objects, mercury re-emission from absorber occurs (the concentration of mercury in the chimney is higher than that before the WFGD absorber) and the sulfide addition to WFGD slurry stops this phenomenon. The addition of sulfide works effectively (mercury removal efficiency from flue gas reaches up to 88% for Polish tests and up to 87% for Czech Republic tests). For the tests in the Poland power plant, all of measured metals are precipitated from the slurry (precipitation of metals efficiency varied from 2% for zinc to 88% for mercury), but in the case of the test in the power plant in the Czech Republic, there is no effect on manganese, iron, and lead (precipitation of metals efficiency varied from 6.5% for copper to 86% for mercury). The addition of sulfide works effectively for lignite mined in Polish and Czech power plants under the conditions of similar WFGD installations. Full article

Houpoea officinalis (H. officinalis) flowers are rich in a spectrum of bioactive compounds and mineral nutrients. The availability and balance of mineral elements directly impact the morphogenesis of flower organs, which play pivotal roles in various physiological and biochemical processes that drive flower development. However, relatively little is known about the changes in mineral elements composition that occur during flower development in H. officinalis. The objective of this study is to analyze the variations of 22 mineral elements contents in pistil, stamens, and petals of H. officinalis flower at four development stages. The amount of mineral elements (Na, Mg, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Sn, Al, Ti, Ga, Cd, Ba, Tl, Pb, and Bi) in these samples was determined using atomic absorption spectroscopy and inductively coupled plasma mass spectrometry. Results showed that H. officinalis flowers are rich in macroelements such as potassium (K, 25.80–48.06 mg/g) and calcium (Ca, 17.27–31.00 mg/g), as well as microelements like zinc (Zn, 445.17–1553.16 μg/g) and iron (Fe, 324.27–622.31 μg/g). Notably, the pistil part is found to harbor a more significant concentration of mineral elements during the early developmental stages of flowers. Correlation analysis and PCA have effectively exposed a pronounced association between the accumulation patterns of mineral elements in H. officinalis flowers and their corresponding developmental stages and organs. These findings will provide more detailed information about the accumulation and distribution of mineral elements in H. officinalis flowers at different development stages and organs, which help to encourage researchers to enhance the flower quality for human consumption. Full article

This study deals with the reconstruction of the paleoenvironment and the paleoclimate situation of the middle–upper Eocene sediments in the northwest Fayum area. The reconstruction is based on comprehensive stratigraphical and geochemical analyses of major oxides and trace elements for selected sediment samples from the Gehannam Formation (Bartonian–Priabonian), the Birket Qarun and the Qasr El Sagha formations (Priabonian). The sedimentological features coupled with paleo-redox trace elemental ratios (Ni/Co, V/Cr, U/Th, V/(V + Ni), and Cu/Zn), paleosalinity (Sr/Ba, Mg/Al ×100, Ca/Al), and paleowater depth (Fe/Mn) proxies, indicate that deposition took place in a shallow marine agitated environment with high oxygen levels. Paleoclimate indicators (Sr/Cu, Rb/Sr, K₂O₃/Al₂O₃, Ga/Rb, C-value, CIA, and CIW) suggest warm and prevailing arid climatic conditions, with minor humid periods at some intervals. The observed low values of the total organic carbon (TOC) are attributed to significant high sediment influx, predominant oxygenated conditions, and poor primary productivity, which is further confirmed by low values of paleoprimary productivity proxies (P, Ni/Al, Cu/Al, P/Al and P/Ti, and Ba_bio ratios). These findings enhance our understanding of the Eocene environments and provide insights into sedimentation processes during this period. Full article

Developing more effective gold–support synergy is essential for enhancing the catalytic performance of supported gold nanoparticles (AuNPs) in the gas-phase oxidation of ethanol to acetaldehyde (AC) at lower temperatures. This study demonstrates a significantly improved Au–support synergy achieved by copper doping in LaMO₃ (M = Mn, Fe, Co, Ni) perovskites. Among the various Au/LaMCuO₃ catalysts, Au/LaMnCuO₃ exhibited exceptional catalytic activity, achieving an AC yield of up to 91% and the highest space-time yield of 764 g_AC g_Au⁻¹ h⁻¹ at 225 °C. Notably, this catalyst showed excellent hydrothermal stability, maintaining performance for at least 100 h without significant deactivation when fed with 50% aqueous ethanol. Comprehensive characterization reveals that Cu doping facilitates the formation of surface oxygen vacancies on the Au/LaMCuO₃ catalysts and enhances Au–support interactions. The LaMnCuO₃ perovskite stabilizes the crucial Cu⁺ species, resulting in a stable Au-Mn-Cu synergy within the Au/LaMnCuO₃ catalyst, which facilitates the activation of O₂ and ethanol at lower temperatures. The optimization of the reaction conditions further improves AC productivity. Kinetic studies indicate that the cleavages of both the O-H bond and the α-C-H bond of ethanol are the rate-controlling steps. Full article

Fast high-temperature gas-phase reactions occurring in the limited space of the arc cavity in the submerged arc welding (SAW) process limit the study of specific gas-phase behaviours. A low-temperature experimental method is applied to investigate gas-phase reactions in the reaction of oxy-fluoride slag with Al-Fe-Ni metal powders. The presence of nano-strands in the slag cavities confirms the vaporisation and re-condensation of gasses. Ti is the main element in nano-strands, although some nano-strands also contain Al-Mg-Si-Na oxy-fluoride. Nano-strand end-caps contain Mn-Fe-Si fluoride, and some contain Ni. The Ni in nano-strand end-caps is sourced from the added Ni powder and indicates gas-phase transfer. The Ti in the nano-strands is sourced from the flux. Themochemistry calculations identify KAlF₄, TiF₃, NaAlF₄, SiF₄, AlF₃, SiF₃, and Na in the gas phase. Increased Al reaction results in decreased TiF₃ in the gas phase, likely due to the displacement of Ti from TiF₃, resulting in the gas-phase transfer of Ti from the flux. Comparative diffusion flux calculations support Ti nano-strand formation via the vaporisation of TiF₃ and the re-condensation of Ti. The low-temperature simulation experiment applied here can be used to study the gas reaction behaviour in the reaction of oxy-fluoride flux with metal powders. Full article