Search Results (8,768)

With the continuous increase in mining activities, effective tailings management has become a critical concern in geotechnical and environmental engineering. This study systematically investigates the microstructural characteristics and 3D reconstruction behavior of copper tailings with different particle sizes using X-ray computed tomography (micro-CT), digital image processing, and 3D modeling techniques. Two particle size groups (fine: 0.075–0.15 mm; coarse: 0.15–0.3 mm) were analyzed to quantify differences in particle morphology, pore structure, and orientation anisotropy. Binary images and reconstructed models revealed that coarse particles tend to have more irregular and angular shapes, while fine particles exhibit more complex pore networks with higher fractal dimensions. The apparent porosity derived from CT data was consistently lower than laboratory measurements, likely due to internal agglomeration effects. Orientation analysis indicated that particle alignment and anisotropy vary systematically with section angle relative to the principal stress direction. These findings offer new insights into the particle-scale mechanisms affecting the packing, porosity, and anisotropy of tailings, providing a scientific basis for enhancing the structural evaluation and sustainable management of tailings storage facilities. Full article

Co-combustion is regarded as an effective means for high-efficiency utilization of low-quality fuels. However, low-quality fuel has problems such as low energy density and high water content. The fuel quality and blending performance can be further optimized by the pretreatment of low-quality fuel, for example, calorific value, hydrophobicity, and NO conversion rate. Based on the idea of co-upgradation, this study systematically investigates the effects of integrated upgrading on fuel quality and hydrophobicity under different conditions. In this study, lignite and wheat straw were selected as research objects. The co-upgrading experiments of wheat straw and lignite were conducted at reaction temperatures of 170 °C, 220 °C, and 270 °C in flue gas and air atmospheres with biomass blending ratios of 0%, 25%, 50%, 75%, and 100%. SEM (scanning electron microscopy) and nitrogen (N₂) adsorption analyses showed that under low-temperature and low-oxygen conditions, organic components from biomass pyrolysis migrated in situ to cover the surface of lignite, resulting in a gradual smoothing of the fuel surface and a decrease in the specific surface area. Meanwhile, water reabsorption experiments and contact angle measurements showed that the equilibrium water holding capacity and water absorption capacity of the lifted fuels was weakened, and hydrophobicity was enhanced. Combustion kinetic parameters and pollutant release characteristics were investigated by thermogravimetric analysis (TGA) and isothermal combustion tests. It was found that co-upgradation could effectively reduce the reaction activation energy and NO conversion rate. Characterized by Raman spectroscopy (Raman) and X-ray photoelectron spectroscopy (XPS), in situ migration of organic components affected combustion reactivity by modulating changes in N-containing product precursors. The results showed that the extracted fuel with a 75% biomass blending ratio in the flue gas atmosphere exhibited the best overall performance at 220 °C, with optimal calorific value, combustion reactivity, and hydrophobicity. These findings may provide important theoretical foundations and practical guidance for the optimization of industrial-scale upgrading processes of low-quality fuels. Full article

Anthropomorphic CT phantoms are essential training tools for interventional radiology. Given the high technical demands and stringent safety requirements in this field, realistic CT phantoms are vital simulation tools that support effective hands-on training, procedural planning, and risk mitigation. However, commercially available phantom geometries are limited in their scope. This study investigates the use of polyvinyl alcohol (PVA) to fabricate customizable training phantoms. PVA, a non-toxic material, can be processed into PVA cryogels (PVA-C) with tissue-like mechanical properties. We modified PVA-C (10 wt.% PVA) by incorporating various additives to adjust X-ray attenuation and achieve Hounsfield units (HUs) similar to different soft tissues. HU values were measured at X-ray tube voltages of 70, 120, and 150 kV. The inclusion of barium sulfate (e.g., U = 120 kV; 0.1–2 wt.%: 33.29 ± 5.45–323.72 ± 12.64 HU) and iohexol (e.g., U = 120 kV; 0.1–2 wt.%: 26.05 ± 4.74–161.99 ± 5.69 HU) significantly increased HU values. Iohexol produced more homogeneous HU distributions than barium sulfate and cellulose derivatives, with the latter having air gaps and inconsistencies. The tested formulations encompassed a wide range of soft tissue densities, with HU values varying significantly across the energy range (p < 0.001). While cellulose derivatives showed variable HU modulation, their primary role appears to be in modifying phantom texture and morphology rather than precise attenuation control. In conclusion, PVA-C demonstrates strong potential for use in interventional radiology training phantoms. Further studies may enhance phantom realism by replicating tissue textures, for example, through the incorporation of cellulose-based substances. Full article

Cerium-doped zinc cobaltite spinel thin films, $\mathrm{Z}\mathrm{n}{\mathrm{C}\mathrm{e}}_{\mathrm{x}}{\mathrm{C}\mathrm{o}}_{2-\mathrm{x}}{\mathrm{O}}_4 (0.00\le \mathrm{x}\le 0.05)$, were synthesized via spray pyrolysis, and their structural, morphological, optical, and electrical properties were analyzed. X-ray diffraction (XRD) confirmed a cubic spinel structure with a predominant (311) orientation across all compositions. Raman spectroscopy further verified this phase, revealing four active vibrational modes at 180 cm⁻¹, 470 cm⁻¹, 515 cm⁻¹, and 682 cm⁻¹. Scanning electron microscopy (SEM) indicated a uniform grain distribution, while energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of Ce, Zn, Co, and O. Optical measurements revealed two distinct bandgaps, decreasing from 2.32 eV to 2.20 eV for the lower-energy transition and from 3.38 eV to 3.18 eV for the higher-energy transition. Hall effect measurements confirmed p-type conductivity in all films. Electrical analysis showed a reduction in resistivity, from 280.3 Ω·cm to 15.4 Ω·cm, along with an increase in carrier concentration from 1.15 × 10¹⁶ cm⁻³ to 8.15 × 10¹⁷ cm⁻³ with higher Ce content. These results demonstrate that spray pyrolysis is a cost-effective and scalable method for producing Ce-doped ZnCo₂O₄ thin films with tunable properties, making them suitable for electronic and optoelectronic applications. Full article

The saturable absorption of 2D Bi₂Te₃ layers is studied by using the Z-scan technique employing infrared 400 fs laser pulses. Optimization of the nonlinearities has been carried out by measuring the third-order nonlinear susceptibilities as a function of the film thickness. A thorough optimization of the thin film annealing conditions has been performed and is presented. For each thickness, the annealing parameters have been separately investigated. Scanning electron microscopy, X-ray diffraction, and UV-Vis spectrophotometry studies have also been performed on the as-deposited and crystallized 2D layers. Full article

Background/Objectives: This study aimed to evaluate the efficacy of a 445 nm diode laser in enhancing enamel resistance to acid-induced demineralization and to investigate the associated compositional and structural modifications using scanning electron microscopy (SEM), electron spectroscopy for chemical analysis (ESCA), and X-ray diffraction (XRD) crystallographic analysis. Methods: A total of 126 extracted human teeth were used. A total of 135 (n = 135) enamel discs (4 × 4 mm) from 90 teeth were assigned to either a laser-irradiated group or an untreated control group for SEM, ESCA, and XRD analyses. Additionally, 24 mono-rooted teeth were used to measure pulp temperature changes during laser application. Laser irradiation was performed using a 445 nm diode laser with a pulse width of 200 ms, a repetition rate of 1 Hz, power of 1.25 W, an energy density of 800 J/cm², a power density of 3980 W/cm², and a 200 µm activated fiber. Following acid etching, SEM was conducted to assess microstructural and ionic alterations. The ESCA was used to evaluate the Ca/P ratio, and XRD analyses were performed on enamel powders to determine changes in phase composition and crystal lattice parameters. Results: The laser protocol demonstrated thermal safety, with minimal pulp chamber temperature elevation (0.05667 ± 0.04131 °C). SEM showed that laser-treated enamel had a smoother surface morphology and reduced acid-induced erosion compared with controls. Results of the ESCA revealed no significant difference in the Ca/P ratio between groups. XRD confirmed the presence of hydroxyapatite structure in laser-treated enamel and detected an additional diffraction peak corresponding to a pyrophosphate phase, potentially enhancing acid resistance. Results of the spectral analysis showed the absence of α-TCP and β-TCP phases and a reduction in the carbonate content in the laser group. Furthermore, a significant decrease in the a-axis lattice parameter suggested lattice compaction in laser-treated enamel. Conclusions: Irradiation with a 445 nm diode laser effectively enhances enamel resistance to acid demineralization. This improvement may be attributed to chemical modifications, particularly pyrophosphate phase formation, and structural changes including prism-less enamel formation, surface fusion, and decreased permeability. These findings provide novel insights into the mechanisms of laser-induced enhancement of acid resistance in enamel. Full article

Background/Objectives: This study reports the synthesis of TiO₂ nanoparticles, their functionalization with folic acid (FA), and the subsequent loading with zinc phthalocyanine (ZnPc) to develop photosensitizers for photodynamic therapy (PDT) targeting glioma cells. Methods: TiO₂, TiO₂-FA, and TiO₂-FA-ZnPc nanoparticles were synthesized via a sol–gel process involving the hydrolysis and condensation of titanium (IV) isopropoxide. FA and ZnPc were incorporated in vitro during the synthesis. The resulting materials were characterized by transmission and scanning electron microscopy (TEM and SEM), X-ray diffraction (XRD), Raman and UV–Vis spectroscopy, thermogravimetric analysis (TGA), and nitrogen adsorption–desorption measurements. Reactive oxygen species (ROS) generation was evaluated in vitro using the 1,3-diphenylisobenzofuran (DPBF) probe. A 40 ppm solution of each TiO₂ system was irradiated with UV light, and the degradation of DPBF was monitored. Biological assays were conducted to assess the viability of human glioblastoma cells (LN18 and U251) incubated with the TiO₂-based materials, with and without UV exposure. Human fibroblast cells (BJ) were used to evaluate biocompatibility. Results: All TiO₂-based materials retained key characteristics, including high surface area (~600–700 m²/g), mesoporous structure (pore diameter ~4–5 nm), mixed anatase–amorphous morphology, and a bandgap of approximately 3.46 eV. The UV–Vis spectrum of TiO₂-FA-ZnPc displayed additional absorption bands in the visible region (600–700 nm), consistent with ZnPc incorporation. Upon UV irradiation, the DPBF absorbance at 410 nm decreased over time, indicating ROS generation and resulting in complete degradation within 10 min (TiO₂), 12 min (TiO₂-FA), and 14 min (TiO₂-FA-ZnPc). BJ cells exhibited good biocompatibility at all concentrations. LN18 and U251 cells showed no cytotoxicity below 100 μg/mL unless exposed to UV light. Conclusions: The synthesized TiO₂-based systems demonstrate good biocompatibility and significant phototoxicity under UV irradiation, highlighting their strong potential for application in photodynamic therapy. Full article

Samples of refined petroleum fuels from the three major oil-marketing companies (GOIL Company Limited, Total Energies Ghana Limited and Shell Vivo Ghana Limited) in Ghana have been analysed for elemental concentrations using an X-ray fluorescence facility at the National Nuclear Research Institute, Ghana Atomic Energy Commission. The samples were acquired from seven different fuel service stations where customers directly purchase refined petroleum fuels such as diesel, petrol and kerosene. The X-ray fluorescence method was considered for the study because sample preparation does not require the addition of reagents, and the fluorescence measurements involve a direct electron transition effect. The fluorescence study was carried out to estimate the concentrations of sulphur and other contaminants in the major refined petroleum fuel products patronised in Ghana. The average sulphur concentration in the samples of diesel products were 17.543, 25.805 and 26.813 ppm in DFS, DE and DXP samples compared to 22.258, 22.623 and 15.748 ppm in petrol samples of PE, PXP and VP. Also, the sulphur concentration of sample KE, kerosene products, is 33.250 ppm. Among the diesel samples, DE and DXP recorded the highest but most comparable average concentration of elemental contaminants, and DFS the least, while PXP recorded the least among the petrol samples. The study estimated the concentrations of four heavy metal elements that are toxic to biological life (Hg, Pb, Cr and Mn) to be less than 10.0 ppm, except Cr. The study concluded that most of the elemental contaminants of heavy metals in the samples were relatively less than ultra-low levels. Therefore, exhaust emissions may have little impact on the environment. Also, the content of the ash-producing metal elements in each sample of the seven refined fuel products is between 10.0 and 50.0 ppm. Since the concentration of sulphur and a few other elemental contaminants could not meet the internationally accepted standard (<10.0 ppm), the imported refined fuel products used in Ghana may be considered relatively good but not environmentally safe. Full article

Hemp stalk, a widely available agricultural waste, is an ideal eco-friendly raw material for biochar production. Carbonization experiments were conducted as a novel approach for the scalable and value-added utilization of hemp stalk under oxygen-exclusion conditions. The effects of feedstock types—Hibiscus cannabinus (KS), Corchorus spp. (JS), and Boehmeria spp. (RS)—and pyrolysis temperatures on biochar properties were analyzed through the measurements of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy. The pH and electrical conductivity (EC) of biochars increased with increasing pyrolysis temperature. Notably, EC was significantly higher for RS (940–2278 μS/cm) than for KS (517–879 μS/cm) and JS (583–863 μS/cm). The C content in these three biochars increased as the temperature increased, whereas the H/C atomic ratio decreased, most notably in JS (by 0.33%). According to FTIR and XRD data, with the pyrolysis temperature increasing, the acidic oxygen-containing groups on biochar surfaces reduced. KS700, with superior aromatic structure and stability, may be able to effectively adsorb heavy metal ions. RS700, with relatively high pH and EC, was suitable for alleviating soil acidification and nutrient deficiency. The feedstock and pyrolysis temperature significantly affected the element content, pore structure, and stability of biochars derived from hemp stalk. Full article

In the quest for greener alternatives to conventional organic solvents, Deep Eutectic Solvents (DESs) have gained significant attention due to their sustainability, biodegradability, and tunability. The use of water as an active and genuine component has recently led to the emergence of water-based DESs (wb-DESs). Here, a careful experimental characterization was performed on choline acetate (ChAc)/water mixtures across a range of water:ChAc molar ratios (n = 2–6). Differential Scanning Calorimetry (DSC) revealed glass transitions between 150 and 180 K, with no first-order transitions, leading to a classification of these mixtures as Low Transition-Temperature Mixtures (LTTMs). Physicochemical measurements, including density, viscosity, electrical conductivity, and refractive index, were conducted over a broad temperature range. NMR analyses provided insights into dynamics and solvation environments, with ¹H T1_slow relaxation times reaching their lowest value at n = 2, consistent with the formation of a strong hydrogen-bonding network. The n = 2 mixture was further investigated using Small and Wide-Angle X-ray Scattering (S-WAXS) and ab initio molecular dynamics (AIMD). These studies, jointly with ¹H NMR choline diffusion coefficient, directly challenge previous claims of the existence of aggregation phenomena in wb-DES. The simulation revealed a well-organized solvation structure, where acetate and water synergistically stabilize the choline cation through a cooperative hydrogen-bonding network. These findings highlight the impact and significance of an integrated physicochemical study in guiding the rational development of new sustainable systems, such as wb-DESs. Full article

The impact of final surface preparation immediately prior to hydrogen content measurements in aluminum alloy samples was investigated using thermal desorption analysis (TDA). Samples ground in water showed an apparent hydrogen signal. Glow-discharge optical emission spectroscopy (GDOES) confirmed that the analyzed hydrogen originated from the subsurface layer. X-ray photoelectron spectroscopy (XPS) revealed the presence of a thin aluminum oxide/hydroxide layer on the surface. Formation of these compounds indicates that hydrogen was introduced into the material by the reaction of oxide-free aluminum with water molecules during the grinding, followed by its entrapment at near-surface interstitial lattice sites. Chemical pickling in concentrated nitric acid and combined grinding, chemical pickling, and electrochemical polishing approaches are proposed as proper surface-preparation techniques for samples without and with adherent corrosion products, respectively. Full article

In this study, ternary NiFeP coatings were fabricated on a copper substrate using a simple, fast, and cost-effective electroless deposition method. The coatings were named Ni₈₅Fe₄P₁₂, Ni₈₀Fe₈P₁₂, and Ni₇₅Fe₁₂P₁₂, indicating 4, 8, and 12 at % of Fe, respectively. The surface morphology and composition of the coatings were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The activity of the prepared coatings was evaluated using the water-splitting reaction to determine the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in a 1 M KOH electrolyte solution. Electrochemical measurements were carried out in a temperature range from 25 °C to 55 °C. The HER and OER current density values increased by up to 2.58 and 2.13 times, respectively, with temperature increase compared to the result at 25 °C. All three coatings demonstrated activity in both reactions. Ni₈₅Fe₄P₁₂ exhibited the highest catalytic efficiency in the HER, with the overpotential of 340 mV at 10 mAcm⁻² and a Tafel slope of 61 mVdec⁻¹. In the OER, the efficiency of the NiFeP catalysts correlated with their Fe content. The overpotential was 412 mV for Ni₈₀Fe₈P₁₂ and 432 mV for Ni₇₅Fe₁₂P₁₂ at 10 mAcm⁻² with Tafel slopes of 96 and 91 mVdec⁻¹, respectively. This study underscores the critical influence of Fe content on the catalytic efficiency of NiFeP coatings, with reduced Fe content enhancing HER and increased Fe content benefits OER. Full article

In recent years, agricultural biomass-filled materials have been increasingly explored as sustainable alternatives to fossil-based polymers and for the development of biocomposites. In this study, micronized hemp stalks, a byproduct of the cannabis industry, were loaded into 10–20% of polypropylene/polyethylene bicomponent fibers in a cost-effective original airlaying process. The production process was developed to achieve high hemp content (up to 80%), while maintaining suitable structural and mechanical properties. Experimental analyses confirmed that the hemp-based biocomposite exhibited promising thermal conductivity values (0.068 ± 0.002 W/mK) and effective sound-attenuation capabilities that are comparable to commonly used insulating materials, such as stone wool. Furthermore, X-ray diffraction and field emission scanning electron microscopy measurements analyzed the insulation features of the hemp-based biocomposite prepared with its morphological and structural properties, revealing its high internal porosity and polymeric crystallinity. These results highlight the potential of hemp biocomposites as sustainable, economically viable alternatives for thermal and acoustic insulation applications. Full article

In this study, a selection of active materials were coated onto commercially available intermediate modulus carbon fibers to form and analyze the performance of novel composite cathodes for structural power composites. Various slurries containing polyvinylidene fluoride (PVDF), active material powders, 1-methyl-2-pyrrolidone (NMP) and carbon black (CB) were used to coat carbon fiber tows by immersion. Four active materials—lithium cobalt oxide (LCO), lithium iron phosphate (LFP), lithium nickel manganese cobalt oxide (NMC), and lithium nickel cobalt aluminum oxide (NCA)—were individually tested to assess their electrochemical reversibility. The cells were prepared with a polymer separator and liquid electrolytes and assembled in 2025-coin cells. Electrochemical analysis of the cathode materials showed that at C/5 and room temperature the measured capacities ranged from 39.8 Ah kg⁻¹ to 64.7 Ah kg⁻¹ for the LFP and NCA active materials, respectively. The full cells exhibited capacities of 18.1, 23.5, 27.2, and 28.2 Ah kg⁻¹ after 55 cycles for LFP, LCO, NCA, and NMC811, respectively. Finally, visual and elemental analysis were performed via scanning electron microscope (SEM) and energy-dispersive x-ray (EDX) confirming desirable surface coverage and successful transfer of the active materials onto the carbon fiber tows. Full article

Redox-active manganese, iron, and nickel complexes of pyridin-2-ylsulfonyl-quinolin-8-yl-amide (psq) provide information for assessing the electronic and structural properties of this new tridentate ligand. Single-crystal X-ray structures show that psq coordinates in a meridional mode with a trigonal geometry for the central deprotonated sulfonamide N donor. With the structures described here, there are now five structures known for hexacoordinated bis-homoleptic complexes of psq. All show the same geometry. No fac isomer, although feasible, has been structurally characterized. The geometrical parameters for [M(psq)₂]^0/+ are surprisingly close to those for archetypical [M(terpy)₂]^2+/3+ (terpy =2,2′:6′,2″-terpyridine) complexes, with octahedral distortion parameters indicating a geometry that is slightly closer to a regular octahedral. The Fe(II) complex, however, bucks this trend, consistent with the magnetic susceptibility measurements indicating a high-spin S = 5/2 state, which stands in contrast to low-spin [Fe(terpy)₂]²⁺. This is rationalized by the trans secondary sulfonamide donors being weaker π acceptors compared to central terpy pyridine donors. An overall two-integer reduced charge for the complexes is consistent with the Co^II/Co^I, M^III/M^II M = Mn, Fe, Co, and Mn^IV/Mn^III redox events being ca. 600–900 mV more cathodic compared to the corresponding events for [M(terpy)₂]²⁺. Full article