Search Results (9,840)

This research studied the recycling of borosilicate glass wastes from damaged laboratory glassware. The luminescent glasses were prepared by doping glass waste powder with rare earth ions, namely, dysprosium ions (Dy³⁺) and samarium ions (Sm³⁺), as well as co-doping with Dy³⁺ and Sm³⁺ at a concentration of 2% by weight. The sintering process was conducted in a microwave oven for a duration of 15 min. The photoluminescence spectra of the doped glasses were obtained under excitation at 401 nm and 388 nm. The results showed that the emission characteristics depended on the doping concentrations of Dy³⁺ and Sm³⁺ and the excitation wavelengths. Upon excitation at 401 nm, the co-doped glasses exhibited the maximum emission peak of Sm³⁺ at 601 nm (yellowish and orange region in the CIE chromaticity diagram) due to the energy transition from ⁴G_5/2 to ⁶H_7/2. When excited at 388 nm, however, the emission spectra of the co-doped glasses were similar to the characteristic emission peaks of Dy³⁺ (white region in the CIE chromaticity diagram), but the peak position exhibits a red shift. This could be attributed to an increase in the amount of non-bridging oxygens (NBOs) by co-doping. Full article

Objectives: This study aimed to assess the performance of the LI-RADS tumor response algorithm in analyzing inter-reader agreement in patients with hepatocellular carcinoma (HCC) treated with Microwave Ablation (MWA) and Transarterial Embolization (TAE) and the relationship between inter-reader agreement and Neutrophils to Lymphocytes ratio dynamic variations at different time points to explore how inflammation influences tumor response and its interpretation on imaging. Methods: A retrospective analysis was conducted on 78 HCC patients treated with MWA or TAE. Two independent radiologists evaluated pre- and post-treatment imaging and assigned categories according to the LR-TRA. Inter-reader agreement was assessed with a focus on subgroup analysis considering the different locoregional treatments. NLR values, measured at baseline (T0), 72 h (T1), and 30 days post-procedure (T2), were compared with patients with concordant and discordant LR-TRA assessments. This analysis aimed to identify any association between NLR dynamics and inter-reader agreement on treatment response. Results: The inter-reader agreement in the LR-TRA application was “substantial” in the cases of MWA treatment evaluation (κ = 0.65), and “moderate” in the cases of TAE treatment evaluation (κ = 0.51). The differences in inter-reader agreement were found to be expressions of different levels of NLR mean values in the different time frames evaluated. Three days after treatment, NLR increased significantly in TAE groups. At 30 days, NLR had returned close to baseline levels but with NLR persisting higher in the TAE group. There was a statistically significant difference in NLR between the “mismatch” group (those with discrepant LR-TRA readings) and the “match” group at 3 days (p = 0.004) and late evaluation (30+ days). Conclusions: This study has shown that NLR levels can predict inter-reader discrepancies in LR-TRA assessment and may be translated into different levels of difficult imaging interpretation. Combining LR-TRA and NLR is promising for a more comprehensive assessment of tumor response and inflammatory dynamics. Full article

Coffee is one of the most widely consumed beverages worldwide. This has motivated the coffee industry to adopt sustainable practices, with an increased emphasis on environmentally friendly extraction methods. The objective of this study was to explore, through a bibliometric analysis, the identification of influential researchers, institutions, emerging topics, and gaps concerning the valorization of coffee by-products and residues using green extraction techniques. A total of 7306 scientific publications on green extraction were identified, 72 specifically addressing coffee or its by-products. The analysis highlights a focus on innovative green technologies, such as natural deep eutectic solvents, ultrasound-assisted or microwave-assisted extraction. These methods enable the efficient and sustainable extraction of bioactive compounds, including polyphenols, chlorogenic acid, caffeine, with potential applications in food, pharmaceutical, and energy industries. Despite this, research on coffee by-products remains limited, partly due to their use in other applications, such as biochar, animal feed, and construction materials, which do not rely heavily on green technologies. Key contributors to the field include countries such as Spain, Italy, Brazil, and China. This study emphasizes the potential of coffee waste to generate high-value products through sustainable methodologies, identifies noteworthy research and key actors in the field, and underscores the necessity for further innovation and collaboration. Full article

This study examined the effects of three sterilization techniques—heat, microwave, and high hydrostatic pressure (HHP)—on the phytochemicals, flavor, and antioxidant properties of high-acidity mulberry vinegar. High-acidity vinegar is valued for its unique sensory properties, preservation potential, and potential health benefits, yet its quality can be significantly impacted by processing methods. Understanding how sterilization affects high-acidity vinegar is crucial for optimizing its functional and nutritional properties while maintaining consumer appeal. Thermal processing (TP) involved heating samples at 85 °C for 15 min, while microwave heating (MH) was performed at 600 W for 40 s. HHP treatments subjected samples to pressures of 400 MPa, 500 MPa, and 600 MPa at ambient temperature (~25 °C) for 15 min. Results showed that total soluble solids (TSS) remained stable at approximately 6.90% across treatments, confirming effective sterilization, especially with HHP. pH values were consistent (3.53–3.55), while total acidity varied, with HHP treatments achieving lower acidity (5.00 g/L). Phytochemical analysis indicated the control (CK) treatment preserved the highest total anthocyanin content (TAC), but HHP₅₀₀ maintained notable levels. HHP treatments also yielded the highest total phenolic (TPC) and total flavonoid content (TFC), highlighting non-thermal sterilization’s advantage in preserving health-promoting compounds. Antioxidant activity, particularly DPPH, was best retained in HHP samples. HHP₅₀₀ showed minimal reductions in key phenolic acids, with decreases of 6.16% in p-hydroxybenzoic acid and 7.81% in total phenolic acid. Volatile organic compound analysis revealed increased ester production, with ethyl acetate peaking at 1775.71 μg/L in HHP₆₀₀. Overall, HHP at 500 and 600 MPa proved superior for producing high-quality mulberry vinegar, supporting the demand for minimally processed, health-focused food products. Full article

This study introduces a data-driven approach to calibrate microscopic traffic simulation models like VISSIM using high-resolution trajectory data, aiming to improve simulation accuracy and fidelity. The study focuses on a highway segment of NJ-3 and NJ-495 in Hudson County, New Jersey, selected as a case study for its high traffic volume and strategic significance. Trajectory data from 338 connected vehicles, sourced from the Wejo dataset, a global provider of anonymized, high-resolution vehicle movement data, along with traffic volume data from Remote Traffic Microwave Sensors (RTMS), served as inputs. The trajectories produced by the simulation model were compared to the ground truth to measure discrepancies. By adjusting driving behavior parameters (e.g., car-following and lane-changing behaviors) and other factors (e.g., desire speed), a Genetic Algorithm was adopted to minimize these differences. Results showed significant improvements, including a 14.19% reduction in mean error, an 18.27% reduction in median error, and a 22.57% reduction in the 75th percentile error during calibration. In the validation phase, the calibrated parameters yielded a 32.68% reduction in mean error, demonstrating the framework’s robustness. This study presents a scalable calibration framework using connected vehicle data, providing tools for accurate simulation, real-time traffic management, and infrastructure planning. Full article

Water pollution caused by emerging contaminants is increasing due to rising urbanization, industrialization, and agriculture production; therefore, new materials with high efficiency for wastewater decontamination are needed. A perovskite material based on 1% Ag-doped LaMnO₃ synthesized through a sol–gel technique was combined with PVP in a 1:10 (w/w) ratio and subjected to different temperature and microwave conditions at various time intervals. The composite materials were obtained as thin films (S1, S2) or powders (S3) and were analyzed by modern techniques. The SEM analysis showed strongly agglomerated, asymmetric formations for the S1, S2 materials; as for the S3 composite, irregularly shaped grains of perovskite were deposited on the polymer surface. Small, round formations across the surface, mainly organized as clusters with conic/square-shaped particles and observed asperity on top, were highlighted by AFM images. The XRD spectra confirmed the presence of both the perovskite and PVP phases, and the crystallite size of the materials was determined to be in the range of 33–43 nm. The structural analyses, FT-IR, and Raman spectroscopy proved the interactions between the perovskite and the polymer, which led to novel composite materials. The different methods used for the synthesis of the new materials influenced their features and behavior. Moreover, the composites were successfully tested for methyl orange (MO) elimination from an acidic aqueous solution in dark conditions, with fast and complete (>95%) MO degradation at pH = 2. Full article

This study investigated the influence of chemical reagent selection on the properties of ZnO nanoparticles synthesized using the microwave-assisted hydrothermal method to control the intensities of near-band-edge (NBE) and defect-related deep-level (DLE) emissions. Two zinc precursors—zinc nitrate and zinc chloride—along with three different precipitating agents (NaOH, KOH, and NH₄OH) were used. ZnO nanoparticles from the ZnCl₂ precursor exhibited two orders of magnitude higher NBE/DLE intensity ratio compared to those obtained from zinc nitrate characterized by a higher contribution from defect-related emissions. Chlorine ions in ZnO nanoparticles play a key role in passivating defects by forming V₀-Cl₂ complexes, quenching luminescence associated with oxygen vacancies (V₀). Thermal treatment in a nitrogen atmosphere enhanced defect-related luminescence, possibly due to chlorine atom diffusion. This study highlights a successful synthesis of ZnO nanoparticles with low defect-related luminescence (DLE) achieved via the microwave-assisted hydrothermal method, a result rarely reported in the literature. The results emphasize the importance of reagent selection in controlling the morphology and optical properties, especially the defect density of ZnO nanoparticles. Optimizing these properties is crucial for biomedical applications such as bioimaging, antibacterial treatments, and photocatalysis. Full article

O. humifusa (Korean Cheonnyencho), a prickly pear cactus species, has garnered increased attention owing to its rich phytochemical composition and potential health benefits. In this study, the antioxidant and anti-cancer activities of a microwave-assisted aqueous extract derived from O. humifusa were investigated, and its phytochemical content was characterized. High-performance liquid chromatography (HPLC) was used to identify various bioactive compounds, including polyphenols, flavonoids, and other antioxidants known for their potential health-promoting properties. Furthermore, the individual compounds in the flavonoids were separated using the HPLC fractionation technique. The antioxidant potential of the aqueous extract was evaluated using 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity. The results demonstrated the significant antioxidant activity of the extract, as evidenced by its ability to scavenge free radicals and effectively reduce oxidized molecules. The experiments involved treating colon cancer cells with varying concentrations of the extract (25 to 125 mg/mL) over a 24-h period, resulting in a remarkable dose-dependent inhibition of cell growth. Notably, this inhibitory effect was absent in HDFa cells, highlighting the potential selectivity of O. humifusa in targeting colon cancer cells. Full article

Microwave-assisted catalytic oxidation (MACO) is a novel wastewater treatment technology for the efficient treatment degradation of organic wastewater. However, a single carbon material or SiC has limited absorption of electromagnetic waves, and the efficiency of using it as a microwave-assisted organic catalyst is not satisfactory. To improve the absorption and microwave-assisted degradation performance of carbon matrix composites, a new carbon magnetic composite Ni@SiC/CNT/CNF microwave catalyst is constructed. By controlling the introduction of nickel, different numbers of carbon nanotubes are grown on the surface of carbon nanofibers, and C and SiC double-shell structures were formed on the top of the carbon nanotubes, which catalyzed the generation of active groups by the thermal effect generated by the plasma discharge under the action of microwave field, thus realizing the highly efficient catalytic degradation of wastewater dyes. The results show that the Ni@SiC/CNT/CNF with the lowest reflection loss of RL_min = −9.26 dB exhibit excellent degradation capabilities with a degradation efficiency of 99.9% for methylene blue within 90 s under 450 W microwave irradiation. Full article

The aim of this study was to determine the influence of the nut roasting process (conventional and microwave methods) and long-term storage (12 months) on phytosterol content and stability. This study was conducted using hazelnuts (Corylus avellana), common walnuts (Juglans regia L.), and shelled peanuts (Arachis hypogaea L.). Two roasting methods were examined: conventional (temp. 170 °C, roasting time 10–20 min.) and microwave (temp. 60 °C, pressure 40 hPa, roasting time 140–180 s). In the studied nuts (raw, roasted and stored), five main types of phytosterols were identified: campesterol, stigmasterol, ß-sitosterol, delta 5-avenasterol and cycloartenol. It was shown that the microwave roasting method caused a two-fold decrease in sterol loss compared with conventional roasting. Moreover, the long-term storage of roasted walnuts using the microwave method showed double the amount of sterols preserved compared with those roasted using the conventional method. The amount of ß-sitosterol, which was the most stable during roasting, depended more on storage duration than on roasting process. The cycloartenol content in the roasted nuts did not depend on storage duration. The sterols present in nuts, raw or roasted using either method, transform more during the first 6 months of storage. Full article

Rare earth elements (REEs) possess unique physical and chemical properties that render them indispensable in various industries, including electronics, energy production and storage, hybrid and electric vehicles, metallurgy, and petro-chemical processing. The criticality of REE underscores the need to enhance the efficiency of primary resource extraction and promote circularity through increased recycling from secondary sources. This paper provides a brief overview of REE recovery from secondary sources, particularly waste from electronic and electric equipment (WEEE). The discussion encompasses direct reuse of magnets, short-loop recycling (direct recycling), hydro- and pyrometallurgical processes, highlighting microwave (MW) technology. Original results are presented, focusing on the recovery of neodymium (Nd) from permanent magnet scraps from hard disk drives (HDD-PC) using microwave-assisted liquid metal extraction (LME) with magnesium (Mg) as the extractant. The subsequent separation of Nd from the Mg-Nd alloy via vacuum Mg distillation that is reused in the process is described. The experimental study demonstrates that the LME process, conducted in a microwave furnace, is a viable method for recovering Nd from permanent magnet scraps, which are essential for reducing the environmental impact of REE extraction and promoting a circular economy. By separating Nd from the alloy through vacuum distillation (450–550 mmHg), at temperatures of 850–900 °C for 8 h, a Nd sponge with a content of 95–98 wt.% Nd was obtained. The extracted content of Nd in the Mg alloy increases with increasing temperature and holding time. It was found that ≈ 97% of the Nd in the scrap was extracted from 2 to 5 mm crushed scrap at 800 °C for 8 h, using a LiF-LiCl-MgF₂ protecting flux in a furnace Ar atmosphere. Full article

Because a finite set of measurements is limited in the amount of spectral content it can represent, the reconstruction process from discrete samples is inherently band-limited. In the case of 1D sampling using ideal measurements, the maximum bandwidth of regular and irregular sampling is well known using Nyquist and Gröchenig sampling theorems and lemmas, respectively. However, determining the appropriate reconstruction bandwidth becomes difficult when considering 2D sampling geometries, samples with variable apertures, or signal to noise ratio limitations. Instead of determining the maximum bandwidth a priori, we derive an inverse method to simultaneously reconstruct a signal and determine its effective bandwidth. This inverse method is equivalent to incrementally computing a band-limited inverse using a frequency-constrained QR decomposition (FQR). Comparisons between reconstruction results using FQR and QR decompositions illustrate how FQR is less sensitive to noisy measurement errors, but it is more sensitive to high-frequency components. These methods are particularly useful in the reconstruction of remote sensing images from such as microwave radiometers and scatterometers. Full article

This study evaluates the potential impact of the Copernicus Imaging Microwave Radiometer (CIMR) mission on the sea surface temperature (SST) products of the Mediterranean Sea. Currently, infrared (IR) radiometers provide accurate, high-resolution SST measurements, but they are limited by their inability to see through clouds. Passive microwave (PMW) radiometers, on the other hand, offer monitoring capabilities in almost all weather conditions but typically at lower spatial resolutions. The CIMR mission represents a notable advance in microwave remote sensing of SSTs, as it will ensure a ≤15 km spatial resolution in the recovered SST field. Using an observing system simulation experiment (OSSE), this study evaluates the effect of inserting synthetic CIMR observations into the Copernicus Mediterranean SST analysis system, which is based on an optimal interpolation (OI) algorithm. The OSSE was conducted using data for the year 2017, including daily SST and salinity outputs from a Mediterranean Sea model, hourly precipitation rates from the IMERG, and wind and cloud cover data from ERA5. The results suggest that the improved spatial resolution and accuracy of the CIMR could potentially improve SST retrievals in the Mediterranean Sea, offering better insights for climate and environmental monitoring in semi-closed basins. Including CIMR data in the OI algorithm reduced the mean error and root mean square error (RMSE) of the SST analysis, especially under conditions of low IR coverage. The greatest improvements were found to occur in July, corresponding to coastal upwelling and Atlantic inflow into the Alboran Sea. Improvements ranged from 16% to 29%, with an overall improvement of 26% for the full year of 2017. In conclusion, this preliminary study indicates that Copernicus Mediterranean Sea HR SST products could benefit from the inclusion of the CIMR in the current IR sensor constellation. Full article

In the area of biomedical diagnostics, microwave imaging techniques have been recently proposed for performing brain stroke detection and monitoring. Indeed, theoretically, these techniques make it possible to meet the timeliness requirements of such a diagnosis with portable systems. Moreover, relying on the use of microwaves, they are noninvasive and allow continuous monitoring of critical patients. In this paper, the microwave imaging problem is solved by exploiting multifrequency data by an inexact-Newton method formulated in the framework of non-constant exponent Lebesgue spaces. First, the method is numerically validated with three-dimensional head models affected by anatomically-realistic strokes. Then, a further assessment through experimental data obtained with a cylindrical phantom is conducted. A quite accurate reconstruction of the variations of dielectric properties inside the patient’s head due to the insurgence of stroke is obtained in both numerical and experimental cases, showing the potentiality of the proposed approach. Full article

Optoelectronic oscillators (OEOs) have emerged as indispensable tools for generating low-phase-noise microwave and millimeter-wave signals, which are critical for a variety of high-performance applications. These include radar systems, satellite links, electronic warfare, and advanced instrumentation. The ability of OEOs to produce signals with exceptionally low phase noise makes them ideal for scenarios demanding high signal purity and stability. In radar systems, low-phase-noise signals enhance target detection accuracy and resolution, while, in communication networks, such signals enable higher data throughput and improved signal integrity over extended distances. Furthermore, OEOs play a pivotal role in precision instrumentation, where even minor noise can compromise the performance of sensitive equipment. This review examines the progress in OEO technology, transitioning from classical designs relying on long optical fiber delay lines to modern integrated systems that leverage photonic integration for compact, efficient, and tunable solutions. Key advancements, including classical setups, hybrid designs, and integrated configurations, are discussed, with a focus on their performance improvements in phase noise, side-mode suppression ratio (SMSR), and frequency tunability. A 20-GHz oscillation with an SMSR as high as 70 dB has been achieved using a classical dual-loop configuration. A 9.867-GHz frequency with a phase noise of −142.5 dBc/Hz @ 10 kHz offset has also been generated in a parity–time-symmetric OEO. Additionally, integrated OEOs based on silicon photonic microring resonators have achieved an ultra-wideband tunable frequency from 3 GHz to 42.5 GHz, with phase noise as low as −93 dBc/Hz at a 10 kHz offset. The challenges in achieving fully integrated OEOs, particularly concerning the stability and phase noise at higher frequencies, are also explored. This paper provides a comprehensive overview of the state of the art in OEO technology, highlighting future directions and potential applications. Full article