Search Results (373)

This study evaluates Natural Deep Eutectic Solvents (NADES) for extracting antioxidant compounds from Portulaca oleracea dried leaves, compared to traditional ethanol extraction. NADES were synthesized using terpenoids (menthol and β-citronellol) and organic acids (lactic and capric acid), characterized by favorable viscosity, density, and pH, ensuring liquid stability at ambient temperature. NADES extraction outperformed ethanol, with NADES 1 yielding the highest bioactive contents: 83.66 Eq GA/mg, 786.55 Eq Q/mg, and 0.78 Eq C/mg versus ethanol’s 58.49 Eq GA/mg, 363.23 Eq Q/mg, and 0.44 Eq C/mg. HPLC-DAD analysis identified higher levels of phenolic acids (caffeic and syringic acid) and flavonoids (rutin and quercetin) in NADES extracts, compounds absent in ethanol. Antioxidant potential, assessed via IC₅₀ values, confirmed superior activity for NADES extracts (NADES 1-Ext: IC₅₀ 28.10 ± 1.73 µg/µL) compared to ethanol (IC₅₀ 1615.97 ± 5.34 µg/µL), and the Trolox method has confirmed extensively this superiority. Additionally, NADES demonstrated improved antimicrobial effects, varying with microorganisms. Despite their high viscosity potentially limiting extraction efficiency, adjusting temperature offers a promising approach to enhance mass transfer. These findings emphasize NADES as a sustainable alternative for bioactive compound extraction, paving the way for optimizing extraction techniques through viscosity reduction strategies. Full article

A huge challenge is how to prepare flexible silicone aerogel materials with good flame retardancy, thermal stability, and hydrophobic properties. In this paper, resorcinol–formaldehyde was introduced into the silicone network composed of methyltrimethoxysilane (MTMS), phenyltriethoxysilane (PTES), and dimethyldimethoxysilane (DMDMS). Flexible hybrid aerogels with excellent thermal insulation, flame retardant, and hydrophobic properties were prepared by the sol–gel method and ambient pressure drying (APD), and the preparation process does not require long-term solvent exchange, only about 3 h of soaking and washing of the wet gel. The results show that the prepared phenolic-silicone aerogel has low density (0.093 g/cm³), low thermal conductivity (0.041 W/m·K), high flexibility, and compression fatigue resistance. The phenolic microspheres are bonded to the silicone skeleton to maintain the original flexibility. After 50% compression deformation, it returns to the original size normally, and there is no significant change in the stress of the sample after 50 compression cycles. Compared with pure silicone aerogels, the hybrid aerogels doped with phenolic have better char yield (65.28%) and higher decomposition temperature (609 °C). The hybrid aerogel sample has good flame-retardant properties, which can withstand alcohol lamp burning without being ignited. The micron-sized phenolic beads give the hybrid aerogels better hydrophobic properties, showing a higher static water contact angle (152°). The excellent thermal and mechanical properties mean that the hybrid aerogels prepared in this paper have good application prospects for aerospace, outdoor equipment, and other fields. Full article

The cold brew method consists of soaking roasted and ground coffee beans either in cold or ambient water (4–23 °C) for up to 24 h. Using this technique, a drink with a unique sensory profile is obtained. This study was conducted to determine the shelf life of a cold brew organic coffee drink (pH~5.0) made from organic beans subjected to three roast levels: light, medium and dark. The drink was pasteurized at 90 °C/30 s, ultra-clean filled into high-density polyethylene bottles, and stored at 4 °C in the dark. Physicochemical, enzymic tests, instrumental color analysis, and microbiological and sensory assays were carried out. The product remained microbiologically stable under refrigeration for all roast levels; however, the beverage made from light roasted beans failed at the beginning of the study, in contrast to the those prepared from medium and dark roasts, which achieved 150 days of shelf life. Full article

A short comparison campaign took place at the Racibórz measurement site in May 2024 to assess the consistency of the Integrated Aerosol Monitoring Unit (IAMU), which houses three PM aerosol sensors (SPS30, OPC-N3, and OPS 3330) within a single enclosure. This assessment was supported by simultaneous measurements from two reference instruments (APS 3321 and SMP S3082), along with auxiliary observations from a ceilometer and meteorological station. To enhance particle transmission efficiency to the IAMU sensors, aerodynamic modeling of the inlet pipes was performed, accounting for particle density and diameter. The primary objective of this study was to evaluate the feasibility of using the IAMU, in conjunction with optimized inlet designs, for PM monitoring under varying ambient relative humidity and sensor temperature conditions. IAMU measurements have shown large absolute differences in PM values (exceeding one order of magnitude) with moderate (>0.54 for PM₁₀) to high (>0.82 for PM_2.5 and PM₁) temporal correlations. A calibration method was proposed, using reference instrument data and incorporating sensor temperature and air sample humidity information. The IAMU, combined with the developed calibration methodology, enabled the estimation of the aerosol growth factor, deliquescence point (RH ≈ 65%), and PM₁ hygroscopic parameter κ (0.27–0.56) for an industrial region in Poland. Full article

The selective depolymerization of β-O-4 lignin models into high-value aromatic monomers using photocatalysis presents both significant opportunities and challenges. Photocatalysts often face issues such as high photogenerated carrier recombination rates and limited operational lifetimes. This study introduces S doping to modulate the surface interface of Bi₃O₄Cl (BOC) nanosheets, enhancing C-O bond cleavage efficiency in β-O-4 lignin models under visible light at ambient temperatures. Comprehensive characterization, including atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), and density functional theory (DFT) analysis, revealed that S doping reduces BOC nanosheet thickness to 1.51 nm and promotes charge carrier separation, thereby generating greater concentrations of reactive species, specifically •O₂⁻ and •OH. Photocatalytic depolymerization experiments demonstrated that S-doped BOC achieved a C-O bond cleavage selectivity of 93% and an aromatic monomer yield of 629.03 μmol/g/h (i.e., 1.5 times higher than that of undoped BOC). This work provides a strategic approach to designing photocatalysts with enhanced selectivity and efficiency for lignin depolymerization. Full article

This study presents a novel approach for monitoring waste substrate digestion under high-density polyethylene (HDPE) geomembranes in sewage treatment plants. The method integrates infrared thermal imaging with a clustering algorithm to predict the distribution of various substrates beneath Traditional outdoor large-scale opaque geomembranes, using solar radiation as an excitation source. The technique leverages ambient weather conditions to assess the thermal responses of HDPE covers. Cooling constants are used to reconstruct thermal images, and clustering algorithms are explored to segment and identify different material states beneath the covers. Laboratory experiments have validated the algorithm’s effectiveness in accurately classifying varied regions by analyzing transient temperature variations caused by natural excitations. This method provides critical insights into scum characteristics and biogas collection processes, thereby enhancing decision-making in sewage treatment management. The methodology under development is anticipated to undergo rigorous evaluation across various floating covers at a large-scale sewage treatment facility in Melbourne. Subsequent to field validation, the implementation of an on-site, continuous thermography monitoring system is envisioned to be further advanced. Full article

In this paper, the macroscopic and microscopic characteristics of diesel spray with elliptical and circular nozzles were investigated under an ambient density of 65.6 kg/m³ by combining an optical test and numerical simulation method of VOF-Spray One-Way Coupling and Large Eddy Simulation. Two elliptical nozzles with varying aspect ratios (1.25 and 1.5) and a circular nozzle were employed for comparison, with the same cross-sectional area. The results demonstrated that the spray tip penetration (STP) of elliptical nozzles was significantly diminished in comparison to that of the circular nozzle and that STP for the elliptical nozzle with a larger aspect ratio was observed to be smaller, primarily due to the elevated aerodynamic drag and accelerated kinetic energy dissipation. The spray cone angle (SCA) of elliptical nozzles was greater than that of the circular nozzle. The average SCA of the elliptical nozzle with a larger aspect ratio was the greatest in both planes. The spray asymmetry with elliptical nozzles resulted in the instability of the spray boundary, leading to the earlier fragmentation and atomization of the spray and faster radial diffusion. For the same STP, the elliptical nozzle with a larger aspect ratio exhibited the greatest spray area in both planes. Elliptical nozzles are subject to a greater degree of inhomogeneous shear than circular nozzles, which results in an accelerated rate of droplet breakage and a concomitant decrease in Sauter Mean Diameter. Full article

A multipronged approach to the refined mechanochemical synthesis of the semiconductor kesterite Cu₂ZnSnS₄ with minimal quantities of adventitious oxygen as well as to optimizing handling procedures from that angle is described. Three precursor systems are used to provide a pool of freshly made cubic prekesterite nanopowders with no semiconductor properties and the thermally annealed at 500 °C tetragonal kesterite nanopowders of the semiconductor. Based on the previously reported high propensity of such nanopowders to long-term deteriorating oxidation in ambient air, suitable modifications of all crucial synthesis steps are implemented, which are directed toward excluding or limiting the materials’ exposure to air. The nanopowders are comprehensively characterized by powder XRD, FT-IR/Raman/UV-Vis spectroscopies, solid-state ⁶⁵Cu/¹¹⁹Sn MAS NMR, TGA/DTA-QMS analysis, SEM, BET/BJH specific surface area, and helium density determinations, and, significantly, are directly analyzed for oxygen and hydrogen contents. The important finding is that following the anaerobic procedures and realistically minimizing the materials’ exposure to air in certain manipulation steps results in the preparation of better oxidation-resistant nanopowders with a dramatic relative decrease in their oxygen content than previously reported. The adherence to the strict synthesis conditions that limit contact of the no-oxygen-containing kesterite nanopowders with ambient air is emphasized. Full article

Automotive-grade GaN power switches have recently been made available in the market from a growing number of semiconductor suppliers. The exploitation of this technology enables the development of very efficient power converters operating at much higher switching frequencies with respect to components implemented with silicon power devices. Thus, a new generation of automotive power components with an increased power density is expected to replace silicon-based products in the development of higher-performance electric and hybrid vehicles. 650 V GaN-on-silicon power switches are particularly suitable for the development of 3–7 kW on-board battery chargers (OBCs) for electric cars and motorcycles with a 400 V nominal voltage battery pack. This paper describes the design and implementation of a 6.6 kW OBC for electric vehicles using automotive-grade, 650 V, 25 mΩ, discrete GaN switches. The OBC allows bi-directional power flow, since it is composed of a bridgeless, interleaved, totem-pole PFC AC/DC active front end, followed by a dual active bridge (DAB) DC-DC converter. The OBC can operate from a single-phase 90–264 Vrms AC grid to a 200–450 V high-voltage (HV) battery and also integrates an auxiliary 1 kW DC-DC converter to connect the HV battery to the 12 V battery of the vehicle. The auxiliary DC-DC converter is a center-tapped phase-shifted full-bridge (PSFB) converter with synchronous rectification. At the low-voltage side of the auxiliary converter, 100 V GaN power switches are used. The entire OBC is liquid-cooled. The first prototype of the OBC exhibited a 96% efficiency and 2.2 kW/L power density (including the cooling system) at a 60 °C ambient temperature. Full article

An electrocatalytic nitrogen reduction reaction (eNRR) presents an appealing strategy for ammonia (NH₃) production at ambient conditions. Through systematic density functional theory (DFT) calculations, the eNRR performance of 23 double-atom catalysts has been investigated. These catalysts are composed of a Mo atom and a transition metal atom anchored on the graphdiyne (GDY), and they are named MoM-GDYs. Among the 23 MoM-GDYs studied, 14 MoM-GDYs highlighted catalytic selectivity by inhibiting a competitive hydrogen evolution reaction (HER) and demonstrated commendable eNRR catalytic performance. MoRu-GDY, MoMo-GDY, MoFe-GDY and MoY-GDY exhibited excellent eNRR catalytic activity with limiting potentials of −0.05 V, −0.13 V, −0.21 V and −0.24 V, respectively. These 14 catalysts favor N₂ adsorption compared to H and exhibit less negative U_L than the −0.98 V benchmark of the stepped Ru(0001) surface. Among them, MoRu-GDY has the best catalytic activity with an U_L of −0.05 V. The excellent catalytic performance originates from the synergistic effect of the dual catalytic sites, where the alternation of the consecutive and enzymatic paths effectively reduces the limiting potentials. In addition, the catalytic activity can be evaluated using ΔG*_NH3 − ΔG*_NH2 as a theoretical descriptor, while U_L and the ΔG*_NH3 − ΔG*_NH2 fit coefficient R² reached 0.99. These findings not only contribute to the development of dual-atom electrocatalysts for eNRR but also offer a valuable pathway for identifying new eNRR catalysts with high activity and selectivity. Full article

Achieving deep-blue light with high color saturation remains a critical challenge in the development of white light-emitting diode (LED) technology, necessitating luminescent materials that excel in efficiency, low toxicity, and stability. Here, we report the synthesis of [N(C₂H₅)₄]₂Cu₂I₄ (TEA₂Cu₂I₄) single crystals (SCs), which exhibit deep-blue photoluminescence (PL) at 450 nm. These crystals are characterized by a significant Stokes shift of 180 nm, a long lifetime of 1.7 μs, and an impressive photoluminescence quantum yield (PLQY) of 96.7% for SCs and 87.2% for polycrystalline films. The zero-dimensional structure is attributed to the proper spacing of triangular inorganic units [Cu₂I₄]²⁻ by organic cations [N(C₂H₅)₄]⁺. This structural arrangement facilitates broadband deep-blue light emission with phosphorescent characteristics, as evidenced by temperature-dependent PL and time-resolved photoluminescence (TRPL) measurements. The band gap properties of TEA₂Cu₂I₄ were further elucidated through density functional theory (DFT) computations. Notably, the material exhibited minimal PL intensity degradation after continuous UV irradiation and one month of exposure to ambient conditions. Moreover, the polycrystalline film of TEA₂Cu₂I₄ maintained substantial deep-blue emission even after one year of storage. Utilizing TEA₂Cu₂I₄ thin film, we fabricated an electroluminescent device emitting deep-blue light with high color saturation, featuring CIE coordinates (0.143, 0.076) and a brightness of 90 cd/m². The exceptional photophysical properties of TEA₂Cu₂I₄ render it a highly promising candidate for optoelectronic applications. Full article

Sodium-ion batteries (SIBs) are advantageous for large-scale energy storage due to the plentiful and ubiquitous nature of sodium resources, coupled with their lower cost relative to alternative technologies. To expedite the market adoption of SIBs, enhancing the energy density of SIBs is essential. Raising the operational voltage of the SIBs cathode is regarded as an effective strategy for achieving this goal, but it requires stable high-voltage cathode materials. Sodium iron sulfate (NFSO) is considered to be a promising cathode material due to its stable framework, adjustable structure, operational safety, and the high electronegativity of SO⁴⁻. This paper reviews the research progress of NFSO, discusses its structure and sodium storage mechanism on this basis, and summarizes the advantages and disadvantages of NFSO cathode materials. This study also evaluates the advancements in enhancing the electrochemical characteristics and structural reliability of SIBs, drawing on both domestic and international research. The findings of this paper offer valuable insights into the engineering and innovation of robust and viable SIB cathodes based on NFSO at ambient temperatures, contributing to their commercial viability. Full article

Light element alloying in iron is required to explain density deficit and seismic wave velocities in Earth’s core. However, the light element composition of the Earth’s core seems hard to constrain as nearly all light element alloying would reduce the density and sound velocity (elastic moduli). The alloying light elements include oxidizing elements like oxygen and sulfur and reducing elements like hydrogen and carbon, yet their chemical effects in the alloy system are less discussed. Moreover, Fe-X-ray Absorption Near Edge Structure (Fe-XANES) fingerprints have been studied for silicate materials with ferrous and ferric ions, while not many X-ray absorption spectroscopy (XAS) studies have focused on iron alloys, especially at high pressures. To investigate the bonding nature of iron alloys in planetary interiors, we presented X-ray absorption spectroscopy of iron–nitrogen and iron–carbon alloys at high pressures up to 50 GPa. Together with existing literature on iron–carbon, –hydrogen alloys, we analyzed their edge positions and found no significant difference in the degree of oxidation among these alloys. Pressure effects on edge positions were also found negligible. Our theoretical simulation of the valence state of iron, alloyed with S, C, O, N, and P also showed nearly unchanged behavior under pressures up to 300 GPa. This finding indicates that the high pressure bonding of iron alloyed with light elements closely resembles bonding at the ambient conditions. We suggest that the chemical properties of light elements constrain which ones can coexist within iron alloys. Full article

Pressurized high-temperature water attracts attention as a promising medium for chemical synthesis, biomass processing or destruction of hazardous waste. Adjustment to the desired solvent properties requires knowledge on the behavior of populations of hydrogen-bonded molecules. In this work, the interconnection between the hydrogen bond (HB) dynamics and the structural rearrangements of HB networks have been studied by molecular dynamics simulation using the modified central force flexible potential and the HB definition controlling pair interaction energy, HB length and HB angle. Time autocorrelation functions for molecular pairs bonded continuously and intermittently and the corresponding mean lifetimes have been calculated for conditions ranging from ambient to supercritical. A significant reduction in the continuous and intermittent lifetimes has been found between (293 K, 0.1 MPa) and (373 K, 25 MPa) and attributed to the decreasing size of patches embedded in the continuous HB network. The loss of global HB connectivity at ca. (573 K, 10 MPa) and the investigated supercritical conditions do not noticeably affect the HB dynamics. Over the whole temperature range studied, the reciprocal intermittent lifetime follows the transition state theory dependence on temperature with the activation energy of 10.4 kJ/mol. Calculations of the lifetime of molecules that do not form hydrogen bonds indicate that at supercritical temperatures, the role of reactions involving an unbound H₂O molecule as a reactant can be enhanced by lowering system density. Full article

The Black Sea, a unique semi-enclosed marine ecosystem, is the eastern maritime boundary of the European Union and holds significant ecological importance. The present study investigates anthropogenic noise pollution in the context of the Marine Strategy Framework Directive’s Descriptor 11, with a particular emphasis on the criteria for impulsive sound (D11C1) and continuous low-frequency sound (D11C2) in Romanian ports, which handle a substantial share of regional cargo traffic, and impact maritime activities and associated noise levels. The noise levels from shipping activity vary across Romanian waters, including territorial waters, the contiguous zone, and the Exclusive Economic Zone. These areas are classified by high, medium, and low ship traffic density. Ambient noise levels at frequencies of 63 Hz and 125 Hz, dominated by shipping noise, were established, along with their hydrospatial distribution for the 2019–2020 period. Furthermore, predictive modeling techniques are used in this study to assess underwater noise pollution from human sources. This modeling effort represents the first initiative in the region and utilizes the BELLHOP ray-tracing method for underwater acoustic channel modeling in shallow-water environments. The model incorporates realistic bathymetry, oceanography, and geology features for environmental input, allowing for improved prediction of acoustic variability due to time-varying sea variations in shallow waters. The study’s findings have important implications for understanding and mitigating anthropogenic noise pollution’s impact on the Black Sea marine ecosystem. Full article