Search Results (655)

This study focused on the dust in the ventilation of the underground coal mine of Ningwu Coalfield, Shanxi Province; the particle-size distribution and the mineralogical and geochemical characteristics of the vent dust were studied. The particle-size distribution of the vent dusts in the exhaust outlets of the four coal mines studied is similar and characterized by a single peak, which occurred at 3.5–4.0 μm. The minerals in the vent dusts are dominantly composed of kaolinite, followed by illite, quartz, calcite, dolomite, bassanite, and anhydrite. Except for the high content of bassanite, the vent dust discharged from the YS coal mine presents a similar mineral composition to the parent coal. Compared with the parent coal (and the Upper Continental Crust), the vent dust is enriched to varying degrees in the major element oxides Fe₂O₃, CaO, K₂O, Na₂O, and MgO, as well as trace elements Sb, Zn, Bi, Cd, Cu, As, W, and Pb, especially the contents of Sb, Zn, W, and As increased by 1177, 84, 15, and 12 times, respectively. The vent dusts emitted from these coal mines mainly come from the mining of coal seams; a small amount comes from the shotcrete and weathering products of the tunnel gallery, dust flame retardant, and the wear of coal cutters and coal transmission belts. Therefore, it is necessary to strengthen the management of coal mine vent dust emission to ensure that the mine vent emissions are pollution-free. Full article

Subjective assessments of air pollution annoyance reveal that individuals’ focus on specific risks is influenced by their attachment to place, beliefs, values, and behavior rather than the composition or toxic effects of air pollutants. Additionally, the social context plays a role in shaping how communities react to and perceive air pollution impacts. This study examines residents’ environmental perceptions regarding the effects of settleable particles before and after the interruption of a large industrial source in the southern region of Espírito Santo, Brazil (South America). A second objective was to model the relationship between air pollution annoyance and other perceived variables under both scenarios. Data were collected through surveys conducted before and after the interruption of the industrial plant. The Pearson chi-square test and ordinal logistic regression model analyzed the data. Results indicate a shift in residents’ concerns with a focus on social and well-being issues. We also found a small number of items relating to dust annoyance and home ownership that can be used to predict the air pollution impact for individual community members. The findings show that settleable particles are directly perceived by exposed populations and significantly affect community health and quality of life. Full article

The creation of bioenergy based on the biomass wood pellet industry, which accounts for the majority of the global biomass supply, is one of the most common and important ways to utilize waste wood, wood dust, and other byproducts of wood manufacturing, known as forestry residues. Pellet production processes might greatly benefit from fast monitoring systems that may allow for at least a semi-quantitative measurement of crucial parameters such as lignin and cellulose. The determination of lignin and cellulose is complicated and time-consuming because it usually requires time-demanding and labor-intensive sample preparation. This, however, might be a crucial problem. In this context, the application of Raman spectroscopic techniques is considered a promising approach, as it enables rapid, reliable, and label-free analysis of wood pellets, providing information about the chemical composition of the biomass, specifically lignin and cellulose. The purpose of this article is to report on the application of Raman spectroscopy exemplified by the detection of the lignin/cellulose ratio. In our methodological approach, we integrated the area under the selected Raman bands to avoid a large scatter of data when only the intensities of the bands were used. Moreover, the acquired Raman spectra displayed very strong signals from both substances, which contributes to the feasibility of the analysis even with a portable instrument. This study is expected to be of assistance in situations when the monitoring of the chemical changes and the quick inspection of pellets are required in near real time, online, and in situ. Full article

This study aimed to verify whether Saharan dust reached south-eastern Poland in spring 2025 and to assess its influence on the chemical composition and oxidative potential of particulate matter. Using an ultra-sensitive Dekati instrument, aerosols were measured across fifteen size fractions (6 nm–10 µm), enabling the detection of particulate matter even in the finest particles—a feature not previously documented for Saharan dust. Electron paramagnetic resonance spectroscopy was used to quantitatively determine and identify radicals associated with different PM fractions. The analysis revealed a high content of ultrafine particulate matter (<1 µm), which may pose a potential risk to human health. The chemical composition of the particulate matter confirmed the long-range transport of Saharan dust over SE Poland at the beginning of March 2025. EPR measurements indicated a relatively large amount of pollutants that exhibited magnetic properties, which were not detected in the control samples. The use of advanced measurement instrumentation enabled the detection of ultrafine fractions and the identification of free radicals associated with Saharan dust, providing new insight into its oxidative potential and chemical reactivity. Full article

The development of sustainable self-compacting concrete (SCC) requires alternative binders that minimise ordinary Portland cement (OPC) consumption while ensuring long-term performance. This study investigates sulfate-activated SCC (SA SCC) incorporating high volumes of industrial by-products, whereby 72% ground granulated blast furnace slag (GGBS) and 18% fly ash (FA) were activated with varying proportions of OPC and gypsum. Quarry dust was used as a fine aggregate, while granite and electric arc furnace (EAF) slag served as coarse aggregates. Among all formulations, the binder containing 72% GGBS, 18% FA, 4% OPC, and 6% gypsum was identified as the optimum composition, providing superior mechanical performance across all curing durations. This mix achieved slump flow within the EFNARC SF2 class (700–725 mm), compressive strength exceeding 50 MPa at 270 days, and flexural strength up to 20% higher than OPC SCC. Drying shrinkage values remained below Eurocode 2 and ASTM C157 limits, while EAF slag increased density, but slightly worsened shrinkage compared to granite mixes. Microstructural analysis (SEM-EDX) confirmed that strength development was governed by discrete C-S-H and C-A-S-H gels surrounding unreacted binder particles, forming a dense interlocked matrix. The results demonstrate that sulfate activation with a 4% OPC + 6% gypsum blend enables the production of high-performance SCC with 94–98% industrial by-products, reducing OPC dependency and environmental impact. This work offers a practical pathway for low-carbon SCC. Full article

This article delineates the outcomes of a comprehensive analysis of occupational conditions in coal mining, focusing on dust exposure. A multifaceted model is proposed for the holistic evaluation of occupational environments, integrating risk assessment methodologies and decision-making frameworks within a risk-based paradigm. Risk assessment involved pairwise comparison, T. Saaty’s Analytic Hierarchy Process, a pessimistic decision-making approach, and fuzzy set membership functions. Correlations were established between respiratory disease risk among open pit coal mine workers and dust generation sources at the project design phase. The risk values were then validated using source attributes and particle physicochemical parameter analysis, including disperse composition and morphology. The risk assessment identified haul roads as a predominant factor in occupational disease pathogenesis, demonstrating a calculated risk level of R = 0.512. The dispersed analysis indicated the prevalence of PM1.0 and submicron particles (≤1 µm) with about 77% of the particle count, the mass distribution showed the respirable fraction (1–5 µm) comprising up to 50% of the total dust mass. Considering in situ monitoring data and particulate morphology analysis haul roads (R = 0.281) and the overburden face (R = 0.213) were delineated as primary targets for the implementation of enhanced health and safety interventions. While most critical at the design stage amidst data scarcity and exposure uncertainty, the approach permits subsequent refinement of occupational risks during operations through the incorporation of empirical monitoring data. Full article

Fungal aerosols are critical yet understudied bioaerosol components in enclosed poultry environments, particularly during winter when ventilation is restricted. This study investigated stage-specific variations in fungal aerosol concentration, size distribution, and community composition in Taihang chicken houses across three growth stages (15, 60, and 150 days). Culturable fungal concentrations significantly increased from 3.16 × 10³ CFU/m³ to 1.24 × 10⁴ CFU/m³ with bird age (p < 0.001, ANOVA). Respirable particles (<4.7 μm) consistently dominated the fungal size distribution. ITS sequencing revealed progressive increases in fungal richness and distinct community shifts among stages. Several fungi with zoonotic potential, including Aspergillus, Cladosporium, Cryptococcus, and Fusarium, were detected across all stages. These findings demonstrate that wintertime enclosed ventilation, while thermally beneficial, promotes the accumulation of respirable fungal aerosols and elevates occupational and environmental health risks. From a One Health perspective, stage-specific mitigation strategies—such as ventilation optimization, reduction in organic dust sources, and routine monitoring of respirable fungal fractions—are essential for reducing exposure risks in cold-season poultry production. Full article

Background/Objectives: The recovery of latent fingerprints from submerged evidence remains a critical challenge in forensic science, as ridge details deteriorate rapidly once under water. This study aims to compare the effectiveness of three established fingerprint development techniques—cyanoacrylate fuming, small particle reagent (SPR), and powder dusting—on non-porous substrates (glass slides and stainless steel blades) immersed in different water types representative of Rajasthan’s Shekhawati region. The objective was to evaluate the influence of water composition and immersion duration on the quality and reproducibility of developed prints. Methods: Experiments were conducted under controlled laboratory conditions. Fingerprints were submerged in hard water, mineral water, and rainwater for durations of 10 min, 1 day, 5 days, and 10 days. Each condition was replicated three times. Developed fingerprints were assessed for ridge clarity using a five-point scoring scale, and the results were statistically analyzed using Chi-Square and correlation tests. Results: Cyanoacrylate fuming consistently produced the highest quality ridge detail across all submersion periods, particularly in mineral and rainwater environments. SPR exhibited moderate effectiveness, while powder dusting showed limited performance under all conditions. Statistical analysis indicated that fingerprint quality was significantly affected by water composition, substrate type, and immersion duration (p < 0.001). Conclusions: The study highlights that fingerprint recovery from submerged non-porous evidence depends strongly on water chemistry and exposure time. Cyanoacrylate fuming is confirmed as the most reliable method, while environmental variables such as ion content and water hardness play decisive roles in fingerprint preservation and visualization. Full article

A leachate from alkaline leaching of copper shaft furnace (CSF) dust as a hazardous waste was used in this study for performing a chemical precipitation experiment of lead, zinc, and copper. The precipitation processes for lead, zinc, and copper were theoretically optimized based on a thermodynamic study. To determine suitable operating conditions, metal phase stability, reaction mechanisms, and precipitation order were analyzed using the Hydra/Medusa and HSC Chemistry v.10 software packages. In the first experimental stage, treatment of the alkaline leachate resulted in the formation of insoluble lead sulfate (PbSO₄), while zinc remained dissolved for subsequent recovery. In the second stage, the zinc-bearing solution was treated with Na₂CO₃, producing a mixed zinc precipitate consisting of Zn₅(OH)₆(CO₃)_2(s). This study determined that the optimal conditions for chemically precipitating lead as PbSO₄ from alkaline leachate (pH 13.5) are the use of 1 mol/L H₂SO₄ at pH 3.09 and Eh 0.22 V at 25 °C, while optimal zinc precipitation from this solution (pH 3.02) is achieved with 2 mol/L Na₂CO₃ at pH 9.39 and Eh –0.14 V at 25 °C. A small amount of copper present in the solution co-precipitated and was identified as an impurity in the zinc product. The chemical composition of the resulting precipitates was confirmed by SEM–EDX analysis. Full article

Aramid Fiber Reinforced Plastic (AFRP) and aluminum alloy Al7075-T6 are widely used in the aerospace industry because they offer a high strength-to-weight ratio and reliable structural performance. However, drilling through stacked AFRP and Al7075-T6 materials in a single operation presents considerable challenges due to the differences in their mechanical and thermal properties. In this study, three types of customized twist drill bits were designed and fabricated to evaluate their effectiveness in single-shot drilling of these stacked materials. The drill geometries included the W-point design, the tapered web design, and the burnishing design. Each drill bit was tested using its own optimized drilling parameters to produce a total of one hundred holes. The aim was to determine which drill geometry provided the best overall performance in terms of tool wear and hole quality. After the drilling experiments, the tool tips were examined using a Scanning Electron Microscope (SEM) to observe wear characteristics and analyze elemental composition. The analysis revealed that aluminum adhered to the cutting lips of all drill bits. The percentage of adhesion layer, known as percentage of adhesion layer (PAL), was calculated to assess the severity of material adhesion. In addition, the morphology of the produced chips and dust was analyzed to support the PAL results. The findings showed that the drill bit with the lowest PAL value demonstrated superior wear resistance, a longer tool life, and the ability to produce holes of higher quality when drilling AFRP and Al7075-T6 stacked materials. Full article

The article presents the results of a study on the production of a complex chromium–manganese–silicon-containing ferroalloy in a large-scale laboratory ore-thermal furnace using man-made waste—chromium-containing aspiration dust obtained during smelting of high-carbon ferrochrome, fines (−5 mm) of iron–manganese ore currently stored in landfills, and finely dispersed coal sludge formed during enrichment. A single-stage technology for the production of a new complex chromium–manganese–silicon-containing ferroalloy by carbothermal reduction is proposed. A metallurgical assessment of the initial charge materials was carried out by the X-ray diffraction (XRD) phase analysis, and metal samples of the obtained ferroalloy were studied by scanning electron microscopy (SEM) in combination with energy dispersive spectroscopy (EDS). The resulting ferroalloy has a complex microstructure with a predominance of carbide and intermetallic phases. A high degree of extraction of chromium (up to 80%), manganese (up to 75%), and silicon (up to 35%) was recorded. The average chemical composition of the obtained ferroalloy, wt.%: Cr—37.41; Mn—17.31; Si—11.84; C—3.81; P—0.14; S—0.02. The slag formed during the smelting of the ferroalloy has satisfactory technological properties: it is characterized by good fluidity, and it actively exits the furnace by gravity. Entanglement of metal kings in the slag is not observed. The results obtained confirm the technological feasibility of the utilization of technogenic raw materials for the production of complex ferroalloys of the FeCrMnSi type. Full article

Exposure of propulsion gas turbines to inlet flow contaminated with dust, sand, or ash particulates can lead to a myriad of complex and interrelated damage modes that reduce engine operational life, increase maintenance costs, and pose a safety risk to passengers and hardware assets. Experimental and computational research is ongoing to better understand the fundamental physics underlying this phenomenon, but data from full-scale engine tests with particles are needed for anchoring and validation under fully representative conditions. In this study, compressor blade/particle interactions are investigated at field-relevant conditions using Rolls-Royce/Allison M250-C20C turboshaft engines in an instrumented engine test cell. A novel experimental dataset was produced, yielding a qualitative visualization of particle impact regions on blades and vanes of an on-engine full six-stage axial compressor at transonic tip speeds for two particle compositions and two inlet particle delivery configurations. This investigation contributes the first experimental dataset of its kind for a rotating frame at transonic blade tip speeds (nominal Mach 1.0). By comparing the resulting impact patterns produced in this work to those of fielded hardware, it is shown that for field-relevant high-Stokes number particle conditions at the first-stage rotor, particle/engine dynamics simplify significantly due to ballistic inertial particle behavior. In addition, the spatial distribution of particle concentration and particle velocities across the compressor inlet plane was found to have only minor effects on the resulting particle/blade impact patterns for the two dust injection configurations tested. Full article

This study presents the development and evaluation of a technology for producing geopolymer-based granulates, which act as sustainable substitutes for natural aggregates by utilizing waste materials. The technology is demonstrated to be energy-efficient compared to other manufactured aggregate processes (such as sintering), as it relies on a cold-bonding process and achieves self-hardening at room temperature. The granulation of geopolymer materials using an intensive counter-current mixer represents an innovative solution in the field of producing substitutes for natural aggregates. Coal fly ash (CFA) was used as the primary aluminosilicate precursor, with composite regrind from decommissioned wind turbine blades (CR) and steelmaking dust (SD) tested as additives. Reactive solids and alkaline activator liquids were mixed and granulated in a single operation using an intensive counter-current mixer; moistening and surface powdering were applied to improve granule sphericity. The granules were cold-cured at room temperature and characterized after 28 days by grain size distribution, crushing resistance, water absorption, abrasion (micro-Deval), SEM/EDS and leaching tests. The results indicate that the additives significantly improved the mechanical performance: PM + PK granules reached crushing strengths > 6 MPa, while CFA + SD granules reached > 11 MPa, exceeding many commercial lightweight aggregates (such as LECA or Lytag), as detailed in the paper. The CFA + CR granulates exhibited a compact microstructure and the effective immobilization of several heavy metals, whereas the CFA + DS samples demonstrated the excessive leaching of Cr, Pb and Mo. The process achieved a high solid-to-liquid ratio (>2.0), reducing activator consumption. Composite regrind is recommended as a promising additive. Full article

Developing bio-based polyurethane (BPU) composites that incorporate bio-oil and wood dust as sources of hydroxyl groups (-OH) presents a compelling approach to advancing sustainable polymer systems. This study examines the impact of isocyanate-to-hydroxyl equivalent ratios and varying proportions of bio-oil and wood dust on the processability and mechanical properties of molded composite panels. Formulations were systematically optimized based on equivalent ratio calculations to enhance extrusion behavior and final structural performance. Extrusion trials demonstrated that an -NCO/-OH ratio of 1.5:1, with 50% wood dust serving as an -OH donor, resulted in the most stable material flow, characterized by minimized surface defects and an ideal viscosity for processing. Compression molding and mechanical testing revealed that a balanced formulation with 50% bio-oil and 50% wood dust, with an equivalent ratio of -OH groups, achieved the best combination of Young’s modulus, stress, and strain performance, even under wet conditions. SEM confirmed improved filler dispersion and interfacial adhesion in these optimized systems. Although full 3D-printing trials were not conducted, the observed extrusion stability and controlled curing behavior indicate strong potential for application in extrusion-based additive manufacturing. These results highlight that precise resin–filler balancing enables continuous extrusion, structural resilience, and reduced activation energy, reinforcing the viability of BPUs as scalable, sustainable materials for construction and additive manufacturing. Full article

Eurydema ventralis has recently intensified in Brassica production in Central and Southeastern Europe, increasing the need for alternatives to conventional insecticides. This laboratory study evaluated five locally sourced inert and plant-derived dusts on the mortality and feeding damage of E. ventralis adults and nymphs. The tested materials were diatomaceous earth, zeolite, quartz sand, wood ash of Norway spruce and Ailanthus altissima leaf dust, compared with an untreated control and a lambda-cyhalothrin control. Mortality and feeding damage were recorded over seven days. The insecticide caused complete mortality in both developmental stages. Diatomaceous earth exhibited the highest efficacy among inert dusts, i.e., 78.3% mortality in adults and 55.2% in nymphs, and a feeding damage index of 3.5. Zeolite and wood ash caused moderate mortality (30.4 and 26.1% in adults; 37.9 and 24.1% in nymphs) and feeding indices of 4.5 and 4.5. A. altissima leaf dust caused low mortality (≤14.5%) but reduced feeding damage (3.7), indicating a deterrent or antifeedant effect. Quartz sand showed negligible efficacy. Diatomaceous earth appears most suitable for integration into sustainable Brassica protection, and A. altissima leaf dust may act as a complementary deterrent, though optimized composition and persistence should be further investigated. Full article