Search Results (2,568)

Potassium–selenium (K-Se) batteries have emerged as a promising energy storage system in view of their high theoretical energy density and low cost. However, their practical application is restricted due to challenges such as polyselenide shuttling, low redox activity, and significant cathode volume expansion during cycling, leading to inferior Coulombic efficiency and a short cycling lifespan. Carbon-based materials, with their superior electronic conductivity, adjustable pore structures, and robust chemical stability, have been extensively studied and employed as cathode materials in K-Se batteries, demonstrating remarkable potential in addressing the above-mentioned issues. Considering the rapidly growing research interest in this topic in recent years, herein, we comprehensively summarize recent advances in the application of carbon-based materials as cathodes in K-Se batteries. First, we introduce the properties, key challenges, and optimization strategies of K-Se batteries, including encapsulating Se within carbon materials, engineering chemisorptive hosts, and electrocatalyzing redox reactions. Furthermore, we discuss the relationship between fabrication strategies, micro/nanostructures, and electrochemical performances. Finally, we propose future prospects for the rational design and application of carbon-based cathodes in K-Se batteries and other alkaline metal–chalcogen batteries. Full article

This paper presents a baseline study on automatic Uzbek text classification. Uzbek is a morphologically rich and low-resource language, which makes reliable preprocessing and evaluation challenging. The approach integrates Term Frequency–Inverse Document Frequency (TF–IDF) representation with three conventional methods: linear regression (LR), k-Nearest Neighbors (k-NN), and cosine similarity (CS, implemented as a 1-NN retrieval model). The objective is to categorize school learning materials by grade level (grades 5–11) to support improved alignment between curricular texts and students’ intellectual development. A balanced dataset of Uzbek school textbooks across different subjects was constructed, preprocessed with standard NLP tools, and converted into TF–IDF vectors. Experimental results on the internal test set of 70 files show that LR achieved 92.9% accuracy (precision = 0.94, recall = 0.93, F1 = 0.93), while CS performed comparably with 91.4% accuracy (precision = 0.92, recall = 0.91, F1 = 0.92). In contrast, k-NN obtained only 28.6% accuracy, confirming its weakness in high-dimensional sparse feature spaces. External evaluation on seven Uzbek literary works further demonstrated that LR and CS yielded consistent and interpretable grade-level mappings, whereas k-NN results were unstable. Overall, the findings establish reliable baselines for Uzbek educational text classification and highlight the potential of extending beyond lexical overlap toward semantically richer models in future work. Full article

A hydrophobic deep eutectic solvent (HDES) composed of Aliquat 336, decanoic acid, and n-hexanol, diluted with kerosene, was investigated for the selective leaching of LiNi_0.33Mn_0.33Co_0.33O₂ (NMC-111) cathode materials. While conventional choline chloride-based DESs co-dissolve Li and transition metals almost completely, the present HDES–acid hybrid system deliberately sacrifices maximum recovery to achieve selectivity. In combination with a low concentration of H₂SO₄, the HDES enabled preferential dissolution of Co and Ni (~84% and ~80% after 6 h at 90 °C, respectively), while Li and Mn largely remained in the solid residue (>93%). Kinetic modeling indicated that the process is controlled by a surface chemical reaction with apparent activation energies of ~~49 kJ mol⁻¹ (for Ni recovery) and ~51 kJ mol⁻¹ (for Co recovery). The leaching residues were enriched in stable Li-Mn-O phases in a way that offers a basis for stepwise recovery. These findings show that hydrophobic eutectic media coupled with mild acid activation provide a sustainable pathway for the selective recycling of LIB cathodes. Full article

Conventional characterization of ultrasonic testing (UT) transducers primarily focuses on determining centre frequency and usable bandwidth. However, the relative amplitude distribution across different frequency components—particularly in low-frequency transducers used for civil engineering applications—remains largely overlooked. This paper introduces a comprehensive methodology to assess the influence of transducer coupling and specimen geometry on ultrasonic pulse velocity signals. The novel approach combines high-frequency laser Doppler vibrometry, real-time photoelastic imaging, and computer simulations using commercial semi-analytical wave-propagation software. The methodology is applied to the characterization of a 250 kHz UT transducer, with particular emphasis on how coupling with a solid test medium alters its frequency response. A glass specimen with an acoustic impedance comparable to that of concrete is used to simulate practical testing conditions. Vibration patterns recorded at the distal end of the specimen are analysed through computer simulations and validated experimentally using a novel photoelastic system capable of capturing wave–specimen interactions at ultrasonic frequencies in real time. The findings offer valuable insights into frequency-dependent signal behaviour and transducer–medium interactions, providing practical guidance for the design and optimization of UT inspections in concrete and other highly attenuative materials commonly encountered in civil engineering. Full article

Ensuring thermal stability is a major concern in lithium-ion battery systems. Although phase change materials (PCMs) provide a passive approach for temperature regulation, they are limited by poor heat conduction and potential leakage during phase transitions. This study develops a novel composite PCM (CPCM) using paraffin (PA) as the matrix, copper foam (CF) as a conductive skeleton (10–30 pores per inch, PPI), and a low-melting-point alloy (LMA) as an encapsulant to prevent leakage. The effects of CF pore size on thermal conductivity, impregnation ratio, and leakage resistance were systematically investigated. Results show that CPCM with 10 PPI CF achieved the highest thermal conductivity (4.42 W·m⁻¹·K⁻¹), while LMA encapsulation effectively eliminated leakage. The thermal management performance was evaluated on both a single 18,650 LIB cell and a 2S2P module during rate discharging at 1C, 2C, and 3C. For the module at 3C, the 10 PPI CPCM significantly lowered the maximum temperature from 75.9 °C to 44.6 °C and critically reduced the maximum temperature difference between cells from 10.2 °C to a safe level of 1.2 °C, significantly improving temperature uniformity. This work provides a high-conductivity and leakage-proof CPCM solution based on LMA-encapsulated CF/PA for enhanced thermal safety and uniformity in LIB modules. Full article

Nowadays, fiber optic cables are a strategic issue because of their importance in telecommunications. Due to the densification of optic cables and the reduction in polymeric layer thickness, the flammability of the external sheath has to be improved. Three novel flame-retardant compositions using phosphate low-melting glasses (LMGs) as aluminum trihydrate (ATH) synergist were assessed in a polyethylene–ethylene vinyl acetate (PE-EVA) matrix. It was highlighted that LMG at a 10 wt% content reduced the peak and mean value of heat release rate (HRR), respectively, to 142 and 90 kW/m² corresponding to 52% and 42% reduction compared to ATH only. Potassium phosphate LMG was shown to perform better than sodium or zinc phosphate LMG. The improvement was assigned to the formation of an expanded mineral layer at the surface of the material during combustion that acts as a thermal shield slowing down the pyrolysis rate. The structural analysis revealed that the presence of alkaline cations in glasses led to short phosphate chains that resulted in low softening point and low-viscosity liquid. It was evidenced that under heat exposure the melted glass is likely to flow between the dehydrating ATH particles, creating a cohesive layer that expands. Additionally, interactions between ATH and LMG were also evidenced. The new crystalline species may also play a role in the cohesion of the layer. Full article

This study investigates the production of chromium–manganese ligature by a metallothermic process using complex silicon–aluminum reducing agents. Low-grade chromium and iron–manganese ores from the Kempirsai and Kerege-Tas deposits in Kazakhstan were used as raw materials, while the reducing agents included alumosilicomanganese alloy (AlSiMn) and ferrosilicoaluminum (FeSiAl). Thermodynamic calculations were performed with HSC Chemistry 10 at 1400–1800 °C and reducing agent dosages of 10–100 kg per 100 kg of ore charge. Crucible smelting experiments were then carried out in a Tamman furnace, followed by large-scale laboratory trials in a 100 kVA refining electric furnace to verify reproducibility, with a total of 14 runs. The chemical composition of the ligatures varied depending on the reductant: with AlSiMn the alloy contained Fe—23.14%, Cr—53.74%, Mn—20.03%, and Si—3.06%; with FeSiAl, it contained Fe—42.01%, Cr—25.74%, Mn—27.15%, and Si—5.05%; and with FeSiCr dust, it contained Fe—34.45%, Cr—21.45%, Mn—39.82%, and Si—4.24%. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed the presence of α-(Fe,Cr,Mn), FeSi, and Cr₅Si₃ phases. The results demonstrate the efficiency of complex silicon–aluminum reducing agents and the ability to regulate the composition of chromium–manganese ligatures by the selected reductant. Full article

For the first time, the kinetics of isothermal curing and thermal degradation of polyethylene glycol maleate (pEGM)–based systems and their composites with mineral fillers were investigated in the presence of a benzoyl peroxide/N,N-Dimethylaniline redox-initiating system. DSC analysis revealed that the curing process at 20 °C can be described by the modified Kamal autocatalytic model; the critical degree of conversion (α_c) decreases with increasing content of the unsaturated polyester pEGM and in the presence of fillers. In particular, for unfilled systems, α_c was 0.77 for pEGM45 and 0.60 for pEGM60. TGA results demonstrated that higher pEGM content and the incorporation of fillers lead to increased thermal stability and residual mass, along with a reduction in the maximum decomposition rate (dTGₘₐₓ). Calculations using the Kissinger–Akahira–Sunose and Friedman methods also confirmed an increase in the activation energy of thermal degradation (E_a): E_KAS was 419 kJ/mol for pEGM45 and 470 kJ/mol for pEGM60, with the highest values observed for pEGM60 systems with fillers (496 kJ/mol for SiO₂ and 514 kJ/mol for CaCO₃). Rheological studies employing three-interval thixotropy tests revealed the onset of thixotropic behavior upon filler addition and an increase in structure recovery after deformation of up to 56%. These findings underscore the potential of pEGM-based systems for low-temperature curing and for the design of composite materials with improved thermal resistance. Full article

New energy vehicles face a critical challenge in balancing the thermal safety management of high-specific-energy battery systems with the simultaneous improvement of energy density. With the large-scale application of high-energy-density systems such as silicon-based anodes and solid-state batteries, their inherent thermal runaway risks pose severe challenges to battery thermal management systems (BTMS). Currently, the thermal insulation performance, temperature resistance, and fire protection capabilities of flame-retardant materials (e.g., foam cotton, fiber felts) used in automotive batteries are inadequate to meet the demands of intense combustion and high temperatures generated during thermal failure in high-energy-density batteries. Against this backdrop, thermal insulation and fireproof aerogel materials are emerging as a revolutionary solution for the next generation of power battery thermal protection systems. Leveraging their nanoporous structure’s exceptional thermal insulation properties (thermal conductivity of 0.013–0.018 W/(m·K) at room temperature) and extreme fire resistance (temperature resistance > 1100 °C/UL94 V-0 flame retardancy), aerogels are gaining prominence. This article provides a systematic review of thermal runaway phenomena in automotive batteries and corresponding protective measures. It highlights recent breakthroughs in the selection of material systems, optimization of preparation processes, and fiber–matrix composite technologies for automotive fireproof aerogel composites. The core engineering values of these materials, such as blocking thermal runaway propagation, reducing system weight, and improving volumetric efficiency, are quantitatively validated. Furthermore, the paper explores future research directions, including the development of low-cost aerogel composites and the design of organic–inorganic hybrid composite structures, aiming to provide a foundation and industrial pathway for the research and development of next-generation high-performance battery thermal management systems. Full article

This work reviews percolation-related phenomena in porous organosilica glass (OSG) low-k dielectrics and their critical impact on mass transport, electrical conductivity, mechanical integrity, and dielectric breakdown. We discuss how leakage current arises from the formation of minimal percolating conductive paths along pores and defect chains, while dielectric breakdown requires system-spanning pore connectivity, resulting in a higher effective percolation threshold. Mechanical properties similarly degrade when pores coalesce into a connected network, exhibiting multiple percolation thresholds due to both chemical network modifications and porosity. Experimental trends demonstrate that leakage current increases sharply at low porosity, whereas breakdown voltage and mechanical stiffness collapse at higher porosity levels (~20%–30%). We highlight that distinct percolation classes govern transport, mechanical, and nonlinear phenomena, with correlation length and diffusion timescales providing a unified framework for understanding these effects. The analysis underscores the fundamental role of network connectivity in determining the performance of organosilicate glass-based ultra-low-k dielectrics and offers guidance for material design strategies aimed at simultaneously improving electrical, mechanical, and chemical robustness. Full article

Modern power systems require better heat dissipation and thermal stability, but traditional low-filler composites cannot significantly enhance thermal conductivity. To address this issue, electric field induction technology orientation can efficiently orient boron nitride nanosheets (BNNSs), thereby improving the thermal conductivity of epoxy composites composed of BNNSs as the thermally conductive filler. In this study, an innovative approach employing a pulsed superimposed direct current (DC) electric field to synergistically induce filler orientation is used to construct efficient thermally conductive channels. The study found that the thermal conductivity of the composite prepared by superimposing an 8 kV/mm pulsed electric field on a 30 V/mm DC electric field is about 0.474 W/(m·K), which is 34.66% higher than that prepared by only a pulsed-induced field and 17.5% higher than the theoretical superposition value. Similarly, the composite prepared by superimposing a 4 kV/mm pulsed electric field on a 70 V/mm DC electric field increased to about 0.464 W/(m·K), which is 27.47% higher than that prepared by only a DC-induced field and 12.4% higher than the theoretical superposition value. These results indicate that the superimposed electric field treatment synergistically improves the thermal conductivity of the composite. Compared to other materials, composites prepared using the superimposed pulsed and DC electric field induction also exhibit superior thermal stability. This strategy effectively addresses the issue of material thermal aging caused by insufficient thermal conductivity, providing innovative ideas and a solid theoretical foundation for material design and thermal management. Full article

Seawater reverse osmosis (SWRO) desalination generates a concentrated brine byproduct rich in dissolved salts and minerals. This study presents an extensive economic and technical analysis of recovering all major ions from SWRO brine, which includes Na, Cl, Mg, Ca, SO₄, K, Br, B, Li, Rb, and Sr in comparison to conventional mining and chemical production of these commodities. Data from recent literature and case studies are compiled to quantify the composition of a typical SWRO brine and the potential yield of valuable products. A life-cycle cost framework is applied, incorporating capital expenditure (CAPEX), operational expenditure (OPEX), and total water cost (TWC) impacts. A representative simulation for a large 100,000 m³/day SWRO plant shows that integrated “brine mining” systems could recover on the order of 3.8 million tons of salts per year. At optimistic recovery efficiencies, the gross annual revenue from products (NaCl, Mg(OH)₂/MgO, CaCO₃, KCl, Br₂, Li₂CO₃, etc.) can reach a few hundred million USD. This revenue is comparable to or exceeds the added costs of recovery processes under favorable conditions, potentially offsetting desalination costs by USD 0.5/m³ or more. We compare these projections with the economics of obtaining the same materials through conventional mining and chemical processes worldwide. Major findings indicate that recovery of abundant low-value salts (especially NaCl) can supply bulk revenue to cover processing costs, while extraction of scarce high-value elements (Li, Rb, Sr, etc.) can provide significant additional profit if efficient separation is achieved. The energy requirements and unit costs for brine recovery are analyzed against those of terrestrial or conventional mining; in many cases, brine-derived production is competitive due to avoided raw material extraction and potential use of waste or renewable energy. CAPEX for adding mineral recovery to a desalination plant is significant but can be justified by revenue and by strategic benefits such as reduced brine disposal. Our analysis, drawing on global data and case studies (e.g., projects in Europe and the Middle East), suggests that metals and salts recovery from SWRO brine is technically feasible and, at sufficient scale, economically viable in many regions. We provide detailed comparisons of cost, yield, and market value for each target element, along with empirical models and formulas for profitability. The results offer a roadmap for integrating brine mining into desalination operations and highlight key factors such as commodity prices, scale economies, energy integration, and policy incentives that influence the competitiveness of brine recovery against traditional mining. Full article

Fermented fruit juices are considered functional beverages because they contain bioactive compounds derived from plant materials and produced by the microorganisms involved in fermentation. The composition of these beverages can vary depending on the strain used. This study aimed to determine the effect of different microorganisms conducting lactic acid fermentation on the chemical composition and bioactive component content of naturally cloudy fermented pear and plum juices. The process used Lactiplantibacillus plantarum K7 bacteria, which were isolated during sauerkraut fermentation, as well as Lachancea thermotolerans PYCC6375 and Lachancea fermentati PYCC5883 yeast cultures, which have poor ethanol fermentation capabilities. The pH, acidity, sugars (HPLC), free amino nitrogen, selected organic acids (HPLC), color (CIELAB), polyphenols (HPLC), volatiles (GC-MS), aroma-active volatiles (GC-MS-O), and sensory characteristics were analyzed. The fermented juices obtained were rich in organic acids (of plant and microbial origin), polyphenols, and had a reduced sugar content (with polyols replacing glucose and fructose), as well as a low alcohol content (<0.2%). At the same time, all three microorganisms significantly enhanced the fruity aroma of the juices. Lachancea yeasts proved to be a viable alternative to lactic acid bacteria for producing fermented juices and were significantly better suited to fermenting plum juices. The highest polyphenol content and highest consumer preference rating were obtained with plum juices fermented with L. fermentati yeast. Full article

Al-Si phase change materials are widely used in solar thermal power generation and industrial waste heat reclamation due to their high heat storage density, high phase transition temperature, and low cost. Hypoeutectic Al-7Si phase change thermal storage alloys with trace La additions were produced through smelting and casting to examine how La affects their microstructural characteristics and thermophysical performance. The findings show that La is adsorbed at the eutectic Si growth interface. Due to the difference in atomic radii, it alters the stacking sequence of Si atoms, generating numerous high-density staggered twins on the {111}Si planes of eutectic Si. La additions modify the morphology of eutectic Si, leading to a morphological transition from lamellar to short rods structures with reduced dimensions. The optimal eutectic Si modification is achieved with 0.06 wt.% La addition. The altered morphology and reduced size of the eutectic Si phase enhance the continuity of the α-Al matrix. This reduces the scattering of free electrons by eutectic Si, increases their mean free path, and ultimately improves the thermal conductivity of the alloy. With 0.06 wt.% La addition, the Al-7Si alloy achieved a peak thermal conductivity of 179.3 W·m⁻¹·K⁻¹, representing a 15.36% enhancement over the unmodified alloy. After 100 thermal cycles, the alloy maintained its phase transition temperature, but the modification effect of La diminished, as evidenced by increased formation of lamellar eutectic Si. Consequently, the latent heat of the Al-7Si-0.06 alloy decreased from 340.4 J/g to 328.6 J/g. Full article

Tungsten monophosphide (WP) has been reported to superconduct below 0.8 K, and theoretical work has predicted an unconventional Cooper pairing mechanism. Here we present data for WP single crystals grown by means of chemical vapor transport (CVT) of ${\mathrm{WO}}_3$, P, and ${\mathrm{I}}_2$. In comparison to synthesis using WP powder as a starting material, this technique results in samples with substantially decreased low-temperature scattering and favors a more three-dimensional morphology. We also find that the resistive superconducting transitions in these samples begin above 1 K. Variation in $T_c$ is often found in strongly correlated superconductors, and its presence in WP could be the result of influence from a competing order and/or a non-s-wave gap. Full article