Search Results (648)

The global demand for sustainable resources highlights agricultural wastes for their valuable biomass content. Xylan, abundant in nature, offers biomedical applications in drug delivery, wound healing, and biodegradable food coatings. This study is the first in the literature to investigate the effect of microwaves on xylan extraction. The aim of this study is to investigate the effect of microwave application and determine the purity of the extraction outcomes in terms of xylan content. The microwave-assisted extractions were performed with two different diluted alkali solutions, potassium hydroxide (KOH) and sodium hydroxide (NaOH), and corncob was the biomass source for xylan. Experiments were designed with response surface methodology (RSM) to find the optimum conditions. Microwave energy demonstrated a statistically significant impact on extraction efficiency and yield (p < 0.05). Maximum yielding conditions for xylan extractions were found as follows: 1200-watt microwave power for 20 min with 10% (w/v) alkaline solution. The results of Fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectra of the KOH extract showed more resemblance to the xylan standard, with fewer indicators of impurities. However, the differential scanning calorimetry (DSC) and zeta potential analysis results of the two extracts did not differ from each other, showing similar thermal and suspension behavior. Xylan content of the KOH and NaOH extracts was determined as 77.82% and 72.01%, respectively. Full article

Wind turbine blade composites represent a growing end-of-life (EoL) waste challenge because thermoset blades lack commercially mature recycling routes, whereas thermoplastic blades offer improved recyclability through dissolution. This study compares the net environmental impact of ten EoL strategies for six 45 m blade configurations comprising thermoset epoxy and thermoplastic Elium resin systems reinforced with glass fiber, carbon fiber, and hybrid laminates, using an eco-audit methodology based on cumulative primary energy demand. Solvolysis is the leading route for thermoset blades and dissolution for thermoplastic blades, reducing net impact to 74.9%, 31.7%, and 22.4% and to 53.6%, 23.4%, and 18.3% of the landfill benchmark for glass-fiber, hybrid, and carbon-fiber configurations, respectively. Thermoplastic blades therefore fall 296.0, 273.1, and 217.2 GJ below their thermoset counterparts. High-voltage fragmentation, conventional pyrolysis, and microwave-assisted pyrolysis are counterproductive for thermoset glass-fiber blades, exceeding landfill by 26.6%, 18.9%, and 8.1%, respectively, because of high process energy and the limited value of recovered glass fiber. Both material-system selection and recycling-route selection govern end-of-life performance, with the route dimension dominating for glass-fiber blades. A Monte Carlo analysis in which all parameters vary simultaneously confirms that solvolysis and dissolution remain the preferred routes for their respective material systems in every run. Thermoplastic blades fall below their thermoset counterparts in 100.0% and 98.8% of runs for glass-fiber and hybrid laminates, but in 80.3% for carbon fiber, where the advantage is indicated rather than established. These results highlight the importance of designing future wind turbine blades through material selection and recyclable composite systems. Full article

Brewer’s spent grain (BSG) is the primary by-product of the brewing industry and a low-cost lignocellulosic resource rich in phenolics, proteins, and arabinoxylans (AXs). Conventional recovery methods using acids, alkalis, and organic solvents often involve energy-intensive processes, generate hazardous waste, and limit food-grade applications. This review critically examines the evolution of extraction methodologies for BSG bioactives, highlighting the potential of deep eutectic solvents (DES) as sustainable alternatives. Key factors such as solvent chemistry (polarity, pH, and water content) influence bioactives’ recovery and selectivity. Process intensification techniques such as ultrasound, microwave, and pressurised liquid extraction enhance efficiency by reducing extraction time and temperature. The review assesses how various processes modify the structure–function properties of BSG bioactives, including antioxidant activity, protein functionality, and rheological behaviour. A significant finding is that DES research has primarily focused on single compounds, while integrated DES biorefineries for comprehensive valorisation remain underexplored. Future research should therefore prioritise integrated process design that balances recovery, structural preservation, functionality, and sustainability to support scalable, near-zero-waste BSG valorisation for food and nutraceutical applications. Full article

This study investigates the formation and evolution of nitrogen-vacancy (NV) centers in nitrogen-doped CVD diamonds. The diamonds were grown via the microwave plasma-assisted chemical vapor deposition (MPACVD) method with different levels of nitrogen doping, then irradiated with helium and hydrogen ions at different energies and doses, followed by low-pressure, high-temperature (LPHT) annealing at 1300 °C and 1400 °C. The presence and intensity of NV⁰ and NV⁻ centers were identified and tracked by photoluminescence spectroscopy after each step. The results showed that both helium and hydrogen irradiation could induce NV center formation, with variation in NV⁰/NV⁻ charge states depending on the irradiation conditions. Helium-irradiated samples generally exhibited stronger NV⁻ signatures; however, the hydrogen-irradiated sample 5N10 (3 MeV, 1 × 10¹³ ions/cm²) displayed the most pronounced NV⁻ presence of all samples, highlighting the critical role of nitrogen content and irradiation parameters. Ion irradiation reduced internal hydrostatic stress in all samples—from up to +0.23 GPa (compressive) in N5 and down to −0.82 GPa (tensile) in N10—relaxing stress toward near-zero values while increasing the Raman FWHM from ~3.5 cm⁻¹ to up to 6.7 cm⁻¹, indicating lattice disorder. LPHT annealing at 1300–1400 °C significantly increased NV-related photoluminescence, indicating effective thermal activation of vacancy-nitrogen recombination. Complementary Raman and FTIR analyses were employed to assess stress and defect evolution. The methodology enabled a comprehensive evaluation of the effects of irradiation and annealing on diamond defect structures, providing relevant experimental data for the controlled engineering of NV centers for quantum technologies. Full article

Soil moisture (SM) is a key parameter in surface water and energy cycles, playing a vital role in agriculture, hydrology, and atmospheric science. Remote sensing (RS) has been widely applied in SM retrieval, yet most existing reviews focus on individual data sources or specific methodologies, lacking a systematic pathway from retrieval principles to product applications, which poses a barrier for early-stage researchers. To address this gap, this study provides a comprehensive review of commonly used SM retrieval models based on different RS data sources, including optical, thermal infrared, active microwave, passive microwave, and multi-source approaches. Their underlying principles, assumptions, advantages, and limitations are critically examined. In parallel, key specifications of major satellite-based SM products, such as spatial-temporal resolution, coverage, and data accessibility, are summarized and compared. By integrating methodological explanations with product characterization, this review serves as a practical reference for researchers entering the field, facilitating informed decisions in SM retrieval applications. Full article

Pomegranate is increasingly being recognized as a versatile source of bioactive compounds with antimicrobial, antioxidant, anti-inflammatory, and microbiota-modulating potential. Beyond the edible arils and juice, peel, seeds, leaves, flowers, and other agro-industrial by-products are rich in ellagitannins, particularly punicalagins, as well as ellagic acid, gallic acid, flavonoids, anthocyanins, fatty acids, and related phytochemicals. Their recovery depends strongly on plant fraction, cultivar, solvent, and extraction technology, including conventional hydroalcoholic extraction, ultrasound- and microwave-assisted processes, high-pressure treatments, and enzyme-assisted methods. Pomegranate-derived preparations exhibit activity against Gram-positive and Gram-negative bacteria, fungi, multidrug-resistant pathogens, and microbial biofilms, while selected compounds may enhance the efficacy of conventional antimicrobials. Emerging evidence also indicates bidirectional interactions with microbial communities, including microbial biotransformation of ellagitannins into urolithins and modulation of beneficial taxa and microbial metabolites. This narrative review integrates agronomic and phytochemical diversity, extraction and standardization strategies, mechanisms of antimicrobial action, synergistic interactions, microbiota-related effects, and applications in food preservation, biomedicine, animal nutrition, agriculture, and environmental sustainability. Key translational limitations include compositional variability, methodological heterogeneity, insufficient standardization, limited in vivo validation, and scarce evidence from realistic application models and clinical studies. Addressing these gaps is essential for developing safe, reproducible, and scalable pomegranate-derived preparations. Full article

Objective: This study aimed to develop and optimize a rapid, eco-friendly microwave-assisted extraction (MAE) process for recovering total phenolic content (TPC) and total flavonoid content (TFC) from garlic (Allium sativum L.), while evaluating the predictive performance of response surface methodology (RSM) versus artificial neural networks (ANNs) and assessing the in vitro gastrointestinal stability of key polyphenols. Methodology: A four-factor, three-level central composite design (CCD) was implemented to evaluate the effects of extraction time, temperature, ethanol concentration, and solvent-to-solid ratio. A second-order polynomial RSM model was benchmarked against a 4-10-2 multilayer perceptron ANN trained by backpropagation. Optimal conditions were derived using the Derringer–Suich desirability function and confirmed experimentally. Individual polyphenols were profiled via LC-MS/MS and monitored across simulated oral, gastric, and intestinal digestion phases. Principal Results: The ANN model demonstrated superior predictive performance (R² = 0.9999 training, 0.9974 validation, 0.9939 testing) compared to the RSM model (R² = 0.9721 for TPC and 0.9925 for TFC). Experimental validation under optimal conditions—1.50 min, 55 °C, 75% ethanol, and a 29 mL/g ratio—yielded a TPC of 2.487 mg GAE/g FW and a TFC of 21.356 mg QUE/g FW. During simulated gastrointestinal digestion, significant degradation occurred during the intestinal phase, resulting in low final recoveries for gallic acid (16.9%), caffeic acid (19.9%), and luteolin (22.6%). Conclusions: MAE coupled with ANN modeling provides a highly accurate, rapid, and green extraction strategy for garlic polyphenols. However, the marked degradation of target compounds during intestinal digestion highlights the necessity of encapsulation or protective delivery systems to preserve their biological functionality in food applications. Full article

The development of safer and more efficient synthetic approaches to insensitive high-energy materials remains important because conventional synthesis may require hazardous reagents and relatively long reaction times. In this study, we aimed to develop improved methods for the synthesis of picrylamino derivatives and evaluate their applicability to the preparation of high-energy materials. Microwave-assisted synthesis was applied to previously known reactions and compared with conventional synthetic approaches. The purity of the synthesized compounds was confirmed by LC-MS analysis, while their impact sensitivity was qualitatively evaluated by bullet impact tests. In addition, the structure of 3-picrylamino-1H-1,2,4-triazole was analyzed to provide insight into its stability. The proposed microwave-assisted approaches substantially reduced reaction times and enabled the use of less hazardous reagents while providing products with good yields and high purity. One of the investigated methods is particularly suitable for the synthesis of 3-picrylamino-1H-1,2,4-triazole because of its slightly higher yield and reduced consumption of harmful picryl chloride; moreover, substitutions in the benzene or triazole ring can be introduced without additional synthetic steps, and the resulting compounds exhibit improved stability and/or detonation performance. These results demonstrate that the proposed methods provide a practical approach to the synthesis of insensitive high-energy materials. The developed methodology may facilitate the preparation and further development of safer, more stable, and high-performance energetic materials. Full article

To improve regeneration performance and shorten desorption time in amine-based CO₂ capture, this study proposes an integrated “blended-amine solvent and microwave regeneration” process. Triethylenetetramine (TETA) was used as the primary absorbent and blended with diethanolamine (DEA) and 2-amino-2-methyl-1-propanol (AMP). Response Surface Methodology (RSM, Box–Behnken design) was employed to establish formulation–performance relationships, and an entropy-weighted TOPSIS method was further applied for multi-objective evaluation and optimization. The optimal formulation consisted of TETA, DEA, and AMP at a mass ratio of 6:1:2. Under the optimized conditions (20 wt% aqueous solvent, 30 °C absorption, 95 °C microwave regeneration), the solvent achieved an absorption capacity of 1.0 mol CO₂·mol⁻¹ amine with a CO₂ recovery of 93.56%. Compared with conventional heating, microwave regeneration markedly accelerated CO₂ desorption, reducing regeneration time from 30 min to 4 min. The estimated total regeneration energy was approximately 2.4 GJ·t⁻¹ CO₂ under microwave heating for the optimized blend. In addition, among the water/n-butanol formulations tested, the fully aqueous system showed the best overall absorption–regeneration performance. Overall, the data-driven solvent design coupled with microwave regeneration offers a practical route toward more efficient CO₂ capture processes. Full article

The valorization of agro-industrial by-products has gained increasing attention as a sustainable strategy to support circular economy principles and reduce environmental impacts. Spain, the world’s largest olive oil producer, generates substantial amounts of olive pomace (OP), which can represent up to 80% of the processed olive mass. Due to their hydrophilic nature, approximately 98% of olive phenolic compounds remain in OP after oil extraction, making this by-product a valuable source of bioactive compounds with antioxidant, anti-inflammatory, antimicrobial, and cardioprotective properties. Numerous extraction strategies have been investigated to maximize phenolic recovery while reducing processing costs and environmental impacts. Conventional solvent-based techniques, such as solid–liquid extraction (SLE) and liquid–liquid extraction (LLE), remain widely used, while greener approaches, including microwave-, ultrasound-, supercritical fluid-, pressurized liquid-, and high-pressure-assisted extraction, among others, have gained increasing attention. In addition, deep eutectic solvents (DES) have been applied either alone or in combination with green extraction technologies to enhance extraction efficiency. This review provides a comprehensive overview of extraction techniques for OP valorization and the analytical methodologies used to characterize OP extracts, including spectrophotometric and chromatographic approaches. The biological activities of OP-derived phenolics and their food applications are also discussed, highlighting their valorization potential. Full article

Niobium-based catalysts have emerged as highly adaptable materials for reactions under heterogeneous conditions, owing to significant advances achieved in synthetic methodologies and characterization strategies. In this review, special attention was paid to analyzing the main methods used to characterize the physicochemical properties (e.g., gas adsorption/desorption, infrared spectroscopy, X-ray diffraction patterns, and temperature-programmed desorption) of solid niobium catalysts, as well as the most widely used and versatile synthesis methods (e.g., microwave-assisted solvothermal synthesis, impregnation, and mechanical milling). These insights can facilitate the rational design of Nb-based catalysts to achieve high activity and selectivity in biomass conversion processes and the valorization of biomass-derived compounds. The developments outlined here underscore the adaptability of niobium materials and provide a comprehensive basis for understanding the relationships between synthesis methodology and physicochemical properties, thereby supporting the development of more efficient Nb-based catalysts for sustainable catalytic applications. Full article

Mechanically aerated yeast-free dough is particularly susceptible to freeze–thaw damage because its porous structure is formed before freezing and cannot be restored during thawing due to the absence of fermentation. This study investigated the combined effects of apple powder incorporation and technological processing conditions on the rheological, structural, physicochemical, nutritional, and sensory properties of whipped yeast-free frozen dough and the resulting bread. Apple powder was incorporated at three formulation levels (50, 100, and 150 g per batch), while whipping speed (450–900 rpm), whipping time (3–7 min), freezing temperature (−14 to −38 °C), and microwave thawing time (4–8 min) were optimized using response surface methodology based on a Draper–Lin composite design. Dough properties were evaluated using Mixolab analysis and structural–mechanical measurements, whereas bread quality was assessed by specific volume, porosity, physicochemical characteristics, biochemical composition, amino acid profile, microbiological safety, and sensory evaluation. The developed regression models adequately described the effects of technological variables on dough quality (R² > 0.95). Deep freezing at −38 °C followed by 4 min of microwave thawing minimized structural deterioration and improved dough stability after freeze–thaw treatment. Apple powder increased the nutritional value of the bread by enhancing the dietary fiber (4.8–7.3%), potassium (125.6–156.7 mg/100 g), iron (2.45–3.20 mg/100 g), and vitamin C (0–2.2 mg/100 g) contents. Although the highest level of apple powder provided the greatest nutritional enrichment, it also reduced the dough rheological stability and produced a less homogeneous crumb structure. Overall, the formulation containing 100 g of apple powder per batch combined with a whipping speed of 900 rpm, whipping time of 7 min, freezing at −38 °C, and microwave thawing for 4 min provided the best balance between rheological stability, freeze–thaw resistance, bread quality, nutritional enhancement, microbiological stability, and sensory acceptability. These findings demonstrate that simultaneous optimization of formulation and processing conditions is an effective strategy for improving mechanically aerated yeast-free frozen bakery products and provides a scientific basis for the development of functional frozen bread technologies. Full article

Polyethylene terephthalate (PET) is a common plastic widely used in food packaging, especially plastic bottles, and in fibers and textiles. The widespread use of PET and its intentional and unintentional release and disposal over the past few decades have placed significant pressure on the environment, necessitating the development of green, low-cost, and efficient recycling technologies to mitigate this impact. This article reviews recent advances in microwave-assisted catalytic depolymerization of PET. It begins by outlining the fundamental principles of PET materials science and depolymerization mechanisms. The article then reviews the historical evolution of this research and presents a benchmark comparison of different depolymerization methodologies. Finally, through a critical analysis and comparison of state-of-the-art approaches, the article identifies emerging trends and highlights promising directions for future research in the field. A comprehensive comparison of conventional and microwave heating methods is presented, indicating that catalyst-assisted microwave systems can shorten reaction times and achieve high product yields under optimized conditions. Key advantages and limitations are highlighted, and persistent challenges are discussed. Overall, this article surveys the latest progress in the chemical recycling of PET and provides critical insights for future research and further development of microwave-assisted catalytic PET depolymerization technology. Full article

Tropospheric refraction significantly impacts the propagation of ultrashort- and microwave-frequency radio waves over marine environments. Atmospheric ducting, the most common super-refractive structure, allows radio waves to travel over the horizon. This holds significant practical value for applications such as maritime communication, remote radar monitoring, and navigation systems. However, atmospheric ducts can also present challenges, especially under unstable meteorological conditions. Atmospheric ducts may cause signal attenuation and even severe interference. Therefore, the detection of atmospheric ducting phenomena is crucial for ensuring the reliability of maritime communication systems and the accuracy of radar monitoring. This paper provides a comprehensive and systematic review of the current state of research on atmospheric duct detection, presenting a detailed analysis of several key methodologies. These include direct measurement techniques, model estimation approaches, numerical forecasting methods, and remote sensing inversion techniques. Additionally, the paper offers an in-depth examination of the strengths and limitations of each method in practical applications, while also highlighting the ongoing challenges within the field. In conclusion, this work aims to provide theoretical foundations and practical guidance for the future development of atmospheric duct detection technologies, fostering further advancements in both theoretical research and technical applications in the field. Full article

Organoselenium chemistry has progressed from the early synthesis of simple selenoorganic molecules in the 20th century to advanced methodologies aligned with the principles of green chemistry. Conventional synthetic approaches, frequently dependent on hazardous reagents and organic solvents, are increasingly being replaced by environmentally benign strategies, including solvent-free reactions, aqueous and bio-based solvent systems, microwave-assisted synthesis, and mechanochemical techniques. These sustainable methodologies offer significant advantages, such as enhanced reaction efficiency, higher or comparable yields, reduced waste generation, improved safety, and lower environmental impact. In parallel, evolving regulatory standards and industrial practices are encouraging the adoption of greener synthetic protocols to minimize hazardous waste and support safer pharmaceutical manufacturing. This review systematically categorizes organoselenium compounds, highlighting their synthetic methodologies, structural characteristics, and biological activities. Overall, recent advances emphasize the therapeutic potential of organoselenium compounds and demonstrate the essential role of sustainable synthetic chemistry in the development of future medicinal agents. Full article