Search Results (584)

In this study, an analysis was carried out of the combustion of pellets made from chamomile and English ryegrass biomass, including those with the addition of kaolin and urea, in terms of their physical and chemical properties. During combustion tests with synchronized timing, the concentrations of CO₂, CO, NO, and SO₂ in the flue gases were measured, along with the temperatures of the supplied air and the flue gases. The addition of kaolin improved combustion parameters, reduced CO emissions, and stabilized the combustion process, despite the deterioration of the mechanical durability of the pellets. Combustion in the drop-in burner (type B tests) showed higher energy efficiency (CEI) and lower flue gas toxicity (TI) than in the grate system (type A tests). The SiO₂ content in the chamomile ash explained its higher resistance to slagging, confirmed by characteristic ash temperatures. Comparison with other biofuels (straw, hay, sawdust) showed similarities or advantages in terms of reducing CO, NO, and SO₂ emissions. NO emissions were lower for pellets with urea and kaolin added, although in the case of biomass with high nitrogen content these relationships require further improvement. The research results indicate the potential of herbaceous biomass as a fuel in local heating systems. However, modification of such fuels is also associated with the need for further research on reducing emissions during unstabilized combustion phases, with particular emphasis on the ignition phase. Full article

Crystal twinning, a common growth phenomenon, can substantially affect material performance in fields such as semiconductors, nonlinear optics, and drug development, yet its elimination during crystallization is challenging. This study presents a method for the controlled synthesis of ZSM-5 zeolite as either single crystals or twinned crystals using kaolin as the primary raw material. The method leverages the etching effect of ammonium fluoride (NH${⁠}_4$F) on the aluminosilicate structure derived from pre-treated kaolin. By adjusting the concentrations of NH${⁠}_4$F and the structure-directing agent tetrapropylammonium bromide (TPABr), pure ZSM-5 single crystals and twinned crystals were selectively synthesized. Conventionally, NH${⁠}_4$F is employed to introduce defects into zeolite structures. In contrast, this work demonstrates its utility in controlling crystal habit. The synthesis utilizes kaolin, an abundant and low-cost aluminosilicate mineral, to provide the entire aluminum source and a portion of the silicon source, offering an economical alternative to expensive precursors like aluminum isopropoxide. The resulting single and twinned crystals exhibited high crystallinity, demonstrating the viability of using natural minerals to produce high-quality zeolites. The physical and chemical properties of the kaolin-derived ZSM-5 were characterized and compared to those of ZSM-5 synthesized from conventional chemical reagents. A growth mechanism for the formation of single and twinned crystals is also proposed. Full article

This study presents an environmentally benign composite hydrogel system by combining polyvinyl alcohol (PVA) with carboxymethyl cellulose derived from jackfruit peel waste (JCMC), subsequently reinforced with graphene oxide (GO) and Kaolin nanoparticles for enhanced Congo red (CR) adsorption. The structural properties of the synthesized hydrogels were comprehensively characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). FTIR analysis confirmed hydrogel formation through hydrogen bonding interactions, while XRD and SEM revealed the uniform dispersion of GO and Kaolin within the polymer matrix, resulting in an improved adsorption performance. Furthermore, the adsorption efficiency of the composite hydrogels was systematically evaluated under varying conditions, including solution pH, contact time, temperature, and initial CR concentration. Optimal CR removal (92.3%) was achieved at pH 8.0, with equilibrium attained within 90 min. The adsorption kinetics were best fitted by the pseudo-second-order model (R² = 0.9998), confirming a chemisorption-dominated process. The equilibrium adsorption data were accurately described by the Langmuir isotherm model, indicating monolayer coverage with an exceptional maximum capacity of 200.80 mg/g. These findings highlight the superior adsorption performance of the PVA/JCMC/GO/Kaolin hydrogels, attributed to their tailored physicochemical properties and synergistic interactions among components. This study offers both sustainable jackfruit peel waste valorization and an effective solution for anionic dye removal in wastewater treatment. Full article

Venoms of the Palearctic vipers in the Macrovipera genus cause severe procoagulant clinical effects, yet the precise molecular targets remain incompletely defined. To fill this toxicological knowledge gap, we tested five Macrovipera venoms—M. lebetina cernovi, M. l. obtusa, M. l. turanica (Turkmenistan and Uzbekistan localities), and M. schweizeri—using plasma clotting assays, Factors VII, X, XI, and XII and prothrombin zymogen activation assays, and SDS-PAGE to visualise Factor V (FV) cleavage. All venoms induced extremely rapid clot formation (10.5–12.5 s) compared with the negative control (spontaneous clotting) of 334.6 ± 3.6 s) and the positive control (kaolin trigger) of 55.8 ± 1.9 s. Activation of FVII or FXI was negligible, whereas consistent FX activation and species-variable FXII activation, both moderate, were observed. Prothrombin remained inert in the absence of cofactors, but the presence of FV or FVa elicited potent thrombin generation. SDS-PAGE confirmed proteolytic conversion of the 330 kDa FV zymogen into the ~105 kDa heavy and ~80 kDa light chains of FVa by the venoms of all species. This data demonstrates that Macrovipera venoms rely on a dual enzyme strategy: (i) activation of FV to FVa by serine proteases and (ii) FVa-dependent prothrombin activation by metalloproteases. These results reveal that prothrombin activation is the dominant procoagulant pathway and overshadows the historically emphasised FX activation. This mechanism mirrors, yet is evolutionarily independent from, the FXa:FVa prothrombinase formation seen in Australian elapid venoms, highlighting convergent evolution of cofactor-hijacking strategies among snakes. The discovery of potent FVa-mediated prothrombin activation in Macrovipera challenges existing paradigms of viperid venom action, prompts re-evaluation of related genera (e.g., Daboia), and underpins the design of targeted antivenom and therapeutic interventions. Full article

Background/Objectives: Platelet activity contributes to myocardial infarction; inadequate inhibition is a risk factor for stent thrombosis and mortality. Inadequate platelet inhibition during treatment is an important risk factor for stent thrombosis and may be associated with increased mortality. This study assessed platelet and coagulation activity in post-MI patients, identifying parameters associated with adverse ST-elevation myocardial infarction (STEMI) outcomes over 3 years, to identify patients needing intensive secondary prevention. Methods: From 57 admitted patients, 19 STEMI patients were analyzed. Thromboelastography (TEG) and Total Thrombus Formation Analysis System (T-TAS) were used to assess hemostasis and coagulation. Selected laboratory parameters were measured for correlations. Major adverse cardiovascular events (MACEs) were defined as ischemic stroke, myocardial infarction, ischemic heart disease, thrombosis, and death from cardiovascular causes. Results: The group with MACEs was characterized by a faster time to initial clot formation and greater reflection of clot strength. T-TAS parameters, such as area under the curve at 10 min (T-TAS AUC10), showed lower values in the same group of patients. A moderate positive correlation suggested that as white blood cell count increases, T-TAS AUC10 values also tend to increase. A strong negative correlation (rho = −1.000, p < 0.01) was observed between low-density lipoprotein and kinetics in the TEG using the kaolin test at baseline in patients with MACEs. Conclusions: Some of the parameters suggest they are associated with adverse outcomes of STEMI, indicate the existence of an inflammatory state, and may contribute to risk stratification of STEMI patients and identify who will require ongoing monitoring. Full article

Dark web traffic classification is an important research direction in cybersecurity; however, traditional classification methods have many limitations. Although deep learning architectures like CNN and LSTM, as well as multi-structural fusion frameworks, have demonstrated partial success, they remain constrained by shallow feature representation, localized decision boundaries, and poor generalization capacity. To improve the prediction accuracy and classification precision of dark web traffic, we propose a novel dark web traffic classification model integrating multi-channel image deep learning and a three-dimensional convolutional neural network (3D-CNN). The proposed framework leverages spatial–temporal feature fusion to enhance discriminative capability, while the 3D-CNN structure effectively captures complex traffic patterns across multiple dimensions. The experimental results show that compared to common 2D-CNN and 1D-CNN classification models, the dark web traffic classification method based on multi-channel image visual features and 3D-CNN can improve classification by 5.1% and 3.3% while maintaining a smaller total number of parameters and feature recognition parameters, effectively reducing the computational complexity of the model. In comparative experiments, 3D-CNN validates the model’s superiority in accuracy and computational efficiency compared to state-of-the-art methods, offering a promising solution for dark web traffic monitoring and security applications. Full article

The sustainable valorization of electrolytic manganese residue (EMR) and fly ash (FA) presents critical environmental challenges. This study systematically investigates the performance optimization of EMR-FA ceramic composites through the coordinated regulation of raw material ratios, sintering temperatures, and additive effects. While the composite with 85 g FA exhibits the highest mechanical strength, lowest porosity, and minimal water absorption, the formulation consisting of 45 wt% EMR, 40 wt% FA, and 15 wt% kaolin is identified as a balanced composition that achieves an effective compromise between mechanical performance and solid waste utilization efficiency. Sintering temperature studies revealed temperature-dependent property enhancement, with controlled sintering at 1150 °C preventing the over-firing phenomena observed at 1200 °C while promoting phase evolution. XRD-SEM analyses confirmed accelerated anorthite formation and the morphological transformations of FA spherical particles under thermal activation. Additive engineering demonstrated that 8 wt% CaO addition enhanced structural densification through hydrogrossular crystallization, whereas Na₂SiO₃ induced sodium-rich calcium silicate phases that suppressed anorthite development. Contrastingly, ZrO₂ facilitated zircon nucleation, while TiO₂ enabled progressive performance enhancement through amorphous phase modification. This work establishes fundamental phase–structure–property relationships and provides actionable engineering parameters for sustainable ceramic production from industrial solid wastes. Full article

As is already known, some currently stable landslides may have been activated in the past along a pre-existing sliding surface and reached the residual strength there, as a consequence of high-cumulative displacements. After a fairly long period of quiescence, these landslides can reactivate due to a temporary increase in destabilising forces capable of mobilising the residual strength along the same sliding surface again. Some recent studies have suggested that, under certain conditions, the strength mobilised upon reactivation may slightly exceed the residual value and then decay towards the latter as the displacement progresses. Regarding this matter, many previous studies have hypothesised that some geotechnical variables could affect the recovered strength more significantly: the length of the ageing time, the vertical stress, the stress history, and the speed with which the reactivation occurs. The aim of this research is to confirm whether such recovery of strength upon reactivation is possible and which geotechnical parameters have the greatest influence on the process. To this end, laboratory tests were carried out with the Bromhead ring shear apparatus on normally consolidated saturated samples of both natural soils and clays provided by industry (bentonite and kaolin). The coupling effect of the ageing time, the vertical stress, and the reactivation speed on the mobilised strength upon reactivation were investigated, starting from a pre-existing residual state of these samples. Within the limits of this research, the results seem to confirm that all three geotechnical variables are influential, with a greater impact on the reactivation speed and, subordinately, on the ageing time for long quiescence periods. Therefore, it is concluded that a quiescent landslide could show a reactivated strength slightly higher than the residual value if the destabilising action could arise with a certain rapidity. Conversely, if the destabilising action occurs very slowly, the mobilised strength could correspond to the residual value. The experimental results of this research may find some application in the design of strengthening works for a stable quiescent landslide that could experience a fairly rapid increase in destabilising actions, such as in the case of seismic stress, morphological modification of the slope, or a rising water table. Full article

This study investigates the effects of NaCl activation on the structural and chemical properties of kaolin for the adsorption of Zn²⁺ from solution. Kaolin was treated with NaCl solution at varying concentrations (0.5, 1.0, 2.0, and 4.0 M), and ultrasonication was used as a means of agitation. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS) were employed to characterize the physical and chemical effects of the NaCl activation and its subsequent influence on the kaolin’s heavy metal removal efficiency. The kaolin activated with 0.5 M NaCl solution yielded the optimal performance with a 13% increase in Zn²⁺ removal compared to the unmodified clay. The adsorption data best matched the pseudo-second-order kinetic model and the Langmuir isotherm. This indicates a monolayer adsorption on a homogeneous surface, with chemisorption as the dominant adsorption mechanism. Thermodynamic analysis also revealed that the adsorption process was endothermic and spontaneous. Furthermore, NaCl activation slightly enhanced the microstructural properties of the kaolin and moderated the surface charge, creating a more favorable electrostatic environment for improved heavy metal ion adsorption. The findings further highlight the potential of NaCl activation to introduce exchangeable Na⁺ onto the kaolin surface in a pH-neutral environment and promise a clean, mechanistically clear, and practical route for ion exchange with heavy metals such as Zn²⁺. Full article

Background/Objectives: The increasing demand for aesthetics in dentistry has driven significant advancements in both materials and techniques. The primary cause of ceramic detachment in dental restorations is extensive mechanical stress, which often results in detachment and clinical complications. This study aims to improve the bond strength between NiCr-based metal frameworks and ceramic coatings by introducing biocompatible inorganic MeSiON thin films (Me = Cr or Zr) as interlayers. Methods: MeSiON coatings with a thickness of ~2 μm were deposited on NiCr alloy using cathodic arc evaporation. To tailor the stoichiometry, morphology, and mechanical properties of the coatings, the substrate bias voltage was varied: −50 V, −100 V, −150 V, −200 V. Structural and surface characterization was performed using SEM/EDS, XRD, profilometry, and contact angle analysis. The coating adhesion was evaluated by using standardized scratch testing, while the bond strength was evaluated using a three-point bending test. Results: The NiCr alloy exhibited a dendritic microstructure, and the ceramic layer consisted mainly of quartz, feldspar, kaolin, and ZrO₂. ZrSiON coatings showed superior roughness, elemental incorporation, and adhesion compared to Cr-based coatings, these properties being further improved by increasing the substrate bias. The highest bond strength was achieved with a ZrSiON coating deposited at −200 V, a result we attributed to increased surface roughness and mechanical interlocking at the ceramic-metal interface. Conclusions: CrSiON and ZrSiON interlayers enhanced ceramic-to-metal adhesion in NiCr-based dental restorations. The enhancement in bond strength is primarily ascribed to substrate bias-induced modifications in the coating’s stoichiometry, roughness, and adhesion. Full article

Environmental challenges such as drought, high temperatures, and salinity compromise grapevine physiology, reduce productivity, and negatively affect grape and wine quality. In recent years, foliar applications of biostimulants, antitranspirants, and phytohormones have emerged as promising strategies to enhance stress tolerance in grapevines. This review focuses on the main effects of salinity, drought, and high temperatures and the combined impact of drought and high temperatures on grapevines and examines how foliar applications influence grapevine responses under these specific stress conditions. Synthesizing the recent findings from the last ten years (160 articles), it provides direct insights into the potential of these compounds to alleviate each type of stress, highlighting their effects on grapevine physiology, yield components, and secondary metabolites in berries. While their mechanism of action is not entirely clear and their efficacy can vary depending on the type of compound used and the grapevine variety, most studies report a beneficial effect or no effect on grapevines under abiotic stresses (either single or combined). Future research is necessary to optimize the concentrations of these compounds and determine the appropriate number and timing of applications, particularly under open-field experiments. Additionally, studies should assess the effect of foliar applications under multiple abiotic stress conditions. In conclusion, integrating foliar applications into vineyard management represents a sustainable technique to mitigate abiotic stresses associated with climate change, such as salinity, water deficit, and heat stress, while preserving or enhancing the quality of grapes and wines. Full article

In this study, natural kaolin was modified with hexadecyltrimethylammonium bromide (HDTMA-Br) at two levels corresponding to 50% and 90% of its cation exchange capacity. The resulting materials, designated as HKR-50 and HKR-90, were used as adsorbents for the mycotoxins ochratoxin A (OCHRA) and zearalenone (ZEN). The characterization of the HKRs with several methods (X-ray diffraction, DRIFT spectroscopy, thermal analysis (DTA/TG), SEM, zeta potential measurements, and the determination of the point of zero charge and textural properties) confirmed the presence of surfactant ions on the organokaolinites’ surfaces. The adsorption of ZEN and OCHRA by HKRs followed nonlinear adsorption isotherms, suggesting a complex adsorption mechanism. The adsorption capacities of ZEN and OCHRA were similar for HKR-50 and HKR-90 at pH 3, with higher adsorption observed for ZEN (~13.0 mg/g for HKR-50 and HKR-90 for ZEN and ~8.0 mg/g for HKR-50 and HKR-90 for OCHRA). At pH 7, the adsorption of ZEN and OCHRA was lower than at pH 3, especially for OCHRA, but slightly increased with increased amounts of surfactant on the kaolinite surface (8.5 mg/g for HKR-50 and 10.8 mg/g for HKR-90 for ZEN and 2.6 mg/g for HKR-50 and 4.1 mg/g for HKR-90 for OCHRA). Special attention was paid to the safety assessment of the natural kaolin and HKR-90, and toxicological tests confirmed the safety of both materials, as no adverse effects were observed in rats. Full article

In this study, free compression tests were conducted to examine the changes in the strength of soil after adding 24 mm long basalt fiber (1%), lime (3%, 6%, 9% by dry weight), and tuff (10%, 20%, 30% by dry weight) before curing and after 28, 42, and 56 days of curing. Instead of the K + BF 1% + SL 9% mixture, where the SL ratio is high, it has been revealed that T, which has a lower SL content and is environmentally friendly (as in the K + BF 1% + SL 6% + T 10% mixture), can be used considering environmental factors and costs. However, due to the length and cost of experimental studies, the use of artificial intelligence to reduce the need for physical tests/experiments and to accelerate processes will provide savings in terms of labor, time, and cost. Unconfined compressive strength (q_u) prediction was performed using the artificial neural network (ANN) technique. The accuracy of the ANN model was proven using the R and MSE metrics. In addition, a q_u prediction of the mixture with 30% water content was performed according to the curing times. The experimental and predicted q_u values for the curing times were compared and presented. Full article

Increasing water scarcity in arid regions has prompted the mining industry to develop strategies to maximize water recovery and reuse, especially in tailings treatment processes. In this context, the present investigation evaluated the effects of sodium polyacrylate (NaPA) on the compressibility and viscoelasticity of clayey tailings in the presence of hard water containing calcium and magnesium. To this end, clayey slurries were analyzed using rheological tests (rheograms and oscillatory viscoelasticity), zeta potential measurements, and compressibility tests using batch centrifugation. The yield stress was determined using the Herschel–Bulkley model, while the compressive yield stress (Py(Φ)) was calculated as a key indicator to characterize the degree of sediment consolidation. The results showed that NaPA, due to its anionic nature and high degree of ionization at pH 8, induces effective particle dispersion by increasing electrostatic repulsion and decreasing the interaction force between particles, which reduces both rheological parameters and compressive yield stress. For the 70/30 quartz/kaolin mixture, the yield stress decreased from 70.54 to 61.64 Pa in CaCl₂ and from 57.51 to 52.95 Pa in MgCl₂ in the presence of NaPA. It was also observed that suspensions in the presence of magnesium ions presented greater compressibility than those with calcium, attributable to the greater hydration radius of magnesium (10.8 Å), which favors less dense and more easily deformable network structures. Furthermore, a higher proportion of kaolin in the mixture resulted in higher yield stresses, a product of the clay’s laminar structure, colloidal size, and high surface area, both in the absence and presence of NaPA. Overall, the results show that incorporating NaPA significantly improves the compressibility and rheology of clayey tailings in hard water, offering a promising alternative for optimizing water recovery and improving tailings management efficiency in the context of water restrictions. Full article

This study presents the results of an investigation of carbonate-containing sorbents for CO₂ capture with natural support materials—kaolin and calcium carbonate—at various loadings of the active phase of Na₂CO₃. The effects of the support type on the distribution of the active component, phase composition, and pore structure of the sorbents were studied. It was found that a Na₂CO₃ loading of 25 wt.% provides the best balance between sorption capacity and technological feasibility. The thermal stability and regeneration capacity of the sorbents were evaluated under high-temperature conditions, revealing high thermal stability of the Na₂CO₃/CaCO₃ system up to 1000 °C, along with its durability over multiple adsorption–desorption cycles. Kinetic studies on the Na₂CO₃/CaCO₃ sorbent using the shrinking core model demonstrated that the overall CO₂ chemisorption process is controlled by surface chemical reaction at temperatures below 50 °C. The obtained results demonstrate the high potential of CaCO₃-based sorbents for practical applications in low-temperature CO₂ capture technologies. A promising direction for the use of such sorbents within CCUS is the development of integrated systems, where CO₂ capture is combined with its conversion into valuable products (e.g., methane, methanol, formic acid) through catalytic processes. Full article