Search Results (7,947)

In this research, ultrasound-assisted extraction (UAE) coupled with response surface methodology was used to identify the optimal process parameters (temperature, time, and solvent composition (ethanol–water ratio)) for bioactive compounds extraction from stalks and debranning products. Extraction efficiency was assessed in terms of total phenolic compounds (TPCs) and antioxidant activity (AA), and phenolic profiles were identified using HPLC-DAD for the four samples of byproducts (two samples from stalks, C1 and C2, and two samples for debranning products, C3 and C4, from two different farms). The optimized extract containing the highest amount of TPC at different levels was used to enrich bread to evaluate the ability of extending their shelf life using a hyperspectral imaging device (935–1720 nm). Under the optimal conditions, the amounts of phenolics on average in stalk increased by about 79.5% and 47.0% in debranning products, whereas the relative AA increased by about 28.5% (C1 and C2 samples) and 63.0% (C3 and C4 samples) when UAE was applied with respect to the traditional technique. The characterization of stalk phenolic acids profile revealed that gallic, ferulic, and 4-coumaric acids were the prevalent ones. Otherwise, caffeic, syringic, and 3-coumaric acids were the most abundant in debranning products. As expected, enriched bread showed a significant increase in TPC and AA values without influence on organoleptic characteristics. Finally, enriched bread showed a shelf-life increase of about five days. Full article

This study aimed to evaluate the impact of contact surface roughness on the performance characteristics of M12-type electrical contacts, with particular emphasis on current and thermal derating parameters. Three samples were prepared, all made from the same conductive material CuZn42, in accordance with identical geometric and technological specifications, differing in the surface roughness value: R_z = 2 μm, representing high surface finish quality, and R_z = 10 μm, representing lower quality. The results showed that the surface roughness of the contact significantly affects the thermal and electrical properties of the tested contacts. Surfaces with lower roughness (R_z = 2 μm) exhibited better electrical conductivity, lower contact resistance, and slower temperature rise as the current load increased. In contrast, contacts with higher roughness (R_z = 10 μm) showed a faster temperature rise and a reduction in the maximum allowable current at higher ambient temperatures. These results could be useful in the design of systems requiring reliability, particularly in high-power devices. Full article

Theoretical U-values, which measure thermal transmittance, can be calculated based on the thermal parameters of an opaque element’s layers. However, practical measurements are essential to validate these theoretical values. The heat flux meter (HFM) method, is a widely accepted standard for such measurements. Despite its prevalence, the HFM method faces challenges, including wall surface roughness, ensuring proper contact between measurement devices and surfaces, and weather-related fluctuations. This study introduces a prototype system that employs a modified temperature-based method (TBM) to address these challenges. The paper provides a detailed comparison of thermal transmittance measurements obtained using both the modified TBM and the HFM method. The results showed U-value differences between the two methods. Additionally, these experimental findings were compared with theoretical calculations, highlighting the efficacy and potential of the modified TBM as an alternative approach for accurate U-value determination. Full article

In Saudi Arabia’s hot and arid climate, residential buildings account for over half of national electricity consumption, with cooling demands alone responsible for more than 70% of this use. This paper explores the hypothesis that contemporary villa designs are inherently inefficient and that current building regulations fall short of enabling adequate thermal performance. This issue is expected to become increasingly significant in the near future as external temperatures continue to rise. The study aims to assess whether passive design strategies rooted in both engineering and architectural principles can offer substantial reductions in cooling energy demand under current and future climatic conditions. A typical detached villa was simulated using IES-VE to test a range of passive measures, including optimized window-to-wall ratios, enhanced glazing configurations, varied envelope constructions, solar shading devices, and wind-tower-based natural ventilation. Parametric simulations were conducted under current climate data and extended to future weather scenarios. Unlike many prior studies, this work integrates these strategies holistically and evaluates their combined impact, rather than in isolation while assessing the impact of future weather in the region. The findings revealed that individual measures such as insulated ceilings and reduced window-to-wall ratios significantly lowered cooling loads. When applied in combination, these strategies achieved a 68% reduction in cooling energy use compared to the base-case villa. While full passive performance year-round remains unfeasible in such extreme conditions, the study demonstrates a clear pathway toward energy-efficient housing in the Gulf region. Full article

This paper investigates data transmission in an Internet of Things (IoT) network, where multiple devices send environmental data to a remote base station through an unmanned aerial vehicle (UAV) relay. The UAV serves as an airborne intermediary that collects status information from distributed IoT devices (e.g., temperature readings in a real-time forest fire monitoring system) and forwards it to the base station. To capture the impact of data staleness, a novel Age of Information (AoI) and entropy-aware system loss is defined in terms of L-conditional cross-entropy, which quantifies the expected penalty caused by state misestimation. The scheduling problem, which aims to minimize the system loss defined by L-conditional cross-entropy, is formulated as a Restless Multi-Armed Bandit (RMAB) problem. By applying Lagrange relaxation, the objective function is decomposed into tractable sub-problems, enabling a low-complexity, gain-index-based scheduling strategy. Numerical simulations validate the effectiveness of the proposed algorithm in reducing the long-term average system loss. In particular, the gain-index-based policy achieves a significant reduction in average penalty compared to random, round-robin, periodic update, and MAX-AoI scheduling strategies, demonstrating its superior performance over these baselines. Full article

The increased use of smartphones in daily life challenges researchers regarding the quality of light emitted by screens. This study aims to analyze displays’ qualitative and quantitative light parameters from various smartphone models available on the market over the last decade. Advanced photometric and colorimetric measurements using complex instrumentation were performed. It covered the color gamut, channel linearity response, refresh rate, flickering, spatial radiation distribution, luminance, uniformity, and static contrast. The analysis showed that, despite advances in smartphone display technology, differences in visible radiation parameters between older and newer models are surprisingly marginal. However, improvements were observed in newer models in terms of viewing angles and compliance with the sRGB standard. Tested built-in blue light reduction filters were ineffective. It only slightly reduces light between 380 nm and 480 nm. In contrast, much higher decreases in this spectral range were achieved for dedicated applications. However, it lowered radiant power density across the visible spectrum, significantly decreasing the displays’ correlated color temperature. Enabling the power-saving mode caused the deterioration of parameters such as refresh rate, but the flicker depth remained constant. Static contrast for most tested devices was also at the same level. The findings confirm the need for further studies on display technology development that supports user well-being while minimizing its harmful effects. Full article

In-plane thermoelectric thin-film cooling devices are considered a promising solution for thermal management in electronic systems. However, the actual cooling performance is far below that of regular bulk cooling devices, making the design of thin-film devices much more difficult. In this work, a numerical analysis of the cooling performance of single-leg thin-film devices and multi-stage cascaded thin-film devices was conducted to understand the depressed cooling performance. The effects of input current, operating environment, substrate, and contact resistance on cooling performance were investigated and compared with the experimental data. The results show that under ideal conditions, including vacuum environment, absence of substrate, and no contact resistance, the maximum cooling temperature difference simulated by the finite element method (105.4 K) closely matches the theoretical value estimated from the ZT-based calculation (96.6 K). Under practical conditions, such as within atmosphere and with substrate and contact resistance, the simulated maximum temperature difference (2.1 K) fits well with the experimental value (1.1 K). These findings demonstrate that substrate effects, contact resistance, and operating environment can significantly impair the cooling performance of in-plane film thermoelectric devices, although high-performance thermoelectric materials were used. This study provides a guidance for the design and parameter optimization of thermoelectric thin-film cooling modules. Full article

In order to apply Ga alloys to flexible and wearable electronic devices, it is crucial to verify the mechanical reliability of interconnections between Ga and various metal electrodes. This study investigated the phase transformation kinetics and microstructural evolution in the Ni/Ga couple. The diffusion reaction behavior between nickel and gallium was characterized from 323 K to 623 K for different annealing times. At temperatures lower than 323 K, no obvious intermetallic compound was identified after annealing, according to SEM observation. For reactions at temperatures higher than 423 K, the Ni₃Ga₇ phase was identified as the only reaction product formed, occurring in a planar morphology along the Ni/Ga interface. The activation energy for the growth of Ni₃Ga₇ was determined as 58.58 kJ/mol. The kinetic equation expressing the relationship between the thickness of interfacial intermetallic compound, annealing temperature, and time, is the following: $d=417174.55\exp \left(-{\displaystyle \frac{58579}{RT}}\right)t^{2.04-0.0024T}$. Full article

The increasing frequency and intensity of heat waves, combined with urban heat islands (UHIs), pose significant public health challenges. Implementing low-cost, real-time monitoring networks with distributed stations within the smart city framework faces obstacles in transforming urban spaces. Accurate data are essential for assessing these effects. This paper compares different network types in a medium-sized city in western Spain and their implications for UHI identification quality. The study first presents a purpose-built monitoring network using Open-Source platforms, IoT technology, and LoRaWAN communications, adhering to World Meteorological Organization guidelines. Additionally, it evaluates two citizen weather observer networks (CWONs): one from a commercial smart device company and another from a global community connecting environmental sensor data. The findings highlight several advantages of bespoke monitoring networks over CWON, including enhanced data accessibility and greater flexibility to meet specific requirements, facilitating adaptability and scalability for future upgrades. However, specialization is crucial for effective deployment and maintenance. Conversely, CWONs face limitations in network uniformity, data shadow zones, and insufficient knowledge of real sensor situations or component characteristics. Furthermore, CWONs exhibit some data inconsistencies in probability distribution and scatter plots during extreme heat periods, as well as improbable UHI temperature values. Full article

Objectives: This study evaluated the design of a sustained-release contact lens (CL) device loading tranilast (TRA) and determined the usefulness of these CLs in Japanese albino rabbits. Methods: The sustainable CLs in this study were prepared by combining three CLs with different water contents and soaking methods under high-pressure and high-temperature using an autoclave method (AC-method). Results: Both the CLs prepared with the conventional soaking method (stir-method) and AC-methods were transparent in all three types of CLs. The loaded TRA contents in the CLs when using the AC-method were higher than those prepared using the stir-method for all three types of CLs. TRA contents were also higher when loaded into the cation-type lenses as compared to the other lenses. Moreover, the sustainable release of TRA from the TRA-loaded cation-type CL using the AC-method was significantly higher than those found for the other CLs. No corneal wounds were observed in any of the rabbits given the three types of TRA-loaded CLs for 7 days. Furthermore, the TRA-loaded CL sustainably released TRA into the lacrimal fluid in the rabbit. Conclusions: The TRA-loaded CL prepared using the AC-method overcame the limitations normally associated with the stir-method, such as the high burst release and low drug uptake. Full article

In this study, we report the synthesis of few-layer graphene via ultrasonic treatment of a graphite-benzene solution at room temperature. Raman spectroscopy revealed a significant reduction in the intensity ratio of the G and 2D peaks for samples subjected to 20 min of treatment, indicating a decrease in defect density and oxidation. Prolonged treatment times led to fragmentation of the graphene sheets, which facilitated restacking, as evidenced by Raman spectroscopy and microscopy. FTIR analysis confirmed the complete removal of the solvent from the extracted and dried graphene. Additionally, electron paramagnetic resonance (EPR) measurements indicated the presence of carbon-based magnetism in the synthesized samples, suggesting potential applications in spintronic devices. Our findings highlight the effectiveness of ultrasonic treatment for producing high-quality few-layer graphene with desirable structural and magnetic properties. Full article

This study presents the synthesis of chitosan nanoparticles (CSNPs) using a microfluidic device. Microfluidic rapid mixing enables fast nucleation for small-sized nuclei, but a high PDI value like 0.956 shows uncontrollable growth of small nuclei, resulting in the formation of larger and more variable aggregates at room temperature. High temperatures play a key role in controlling the growth of CSNPs to enhance uniformity. Temperatures of 40 °C and 50 °C promote controlled interactions among small nuclei, while increasing the temperature to 80 °C further accelerated the curing process, suitable for synthesizing CSNPs with various sizes. At 80 °C, size regulation can be achieved by changing the TPP concentration, which controls surface curing and affects the size as well. These results emphasize the impact of elevated temperature and precise TPP concentration for product quality control and modulation in CSNPs’ synthesis. Full article

The gate reliability issues in SiC-based devices with a gate dielectric formed through heat oxidation are important factors limiting their application in power devices. Aluminum oxide (Al₂O₃) and titanium dioxide (TiO₂) were combined using the ALD process to form a composite AlTiO gate dielectric on a 4H-SiC substrate. TDMAT and TMA were the precursors selected and deposited at 200 °C, and the samples were Ar or N₂ annealed at temperatures ranging from 300 °C to 700 °C. An XPS analysis suggested that the AlTiO film had been deposited with a high overall quality and the involvement of Ti atoms had increased the interfacial bonding with the substrate. The as-deposited MOS structure had band shifts of ΔE_C = 1.08 eV and ΔE_V = 2.41 eV. After annealing, the AlTiO bandgap increased by 0.85 eV at most, and better band alignment was attained. Leakage current and breakdown voltage characteristic investigations were conducted after Al electrode deposition. The leakage current density and electrical breakdown field of an MOS capacitor structure with a SiC substrate were ~10⁻³ A/cm² and 6.3 MV/cm, respectively. After the annealing process, both the measures of the JV performance of the MOS capacitor had improved to ~10⁻⁶ A/cm² and 7.2 MV/cm. The interface charge N_eff of the AlTiO layer was 4.019 × 10¹⁰ cm⁻². The AlTiO/SiC structure fabricated in this work proved the feasibility of adjusting the properties of single-component gate dielectric materials using the ALD method, and using a suitable thermal annealing process has great potential to improve the performance of the compound MOS dielectric layer. Full article

Soil temperature and soil moisture are significant interactive parameters that influence many ecological and hydrological processes within forest ecosystems. Furthermore, they are affected by the above canopy characteristics, which determine the amount of sunlight penetration. These canopy characteristics spatially vary within isolated or narrowed forest patches, which include interior parts and edges. On the other hand, forest patches display different effects on the soil temperature and moisture than agricultural meadows within rural landscapes. This study aimed to analyze and evaluate the influences of interior–edge canopies and meadow cover on soil temperature and moisture. Hence, the mutual responses of canopy phenology and physiology, along with the soil temperature and moisture beneath, were analyzed and determined on a temporal basis throughout one year. For this purpose, the air–soil temperature and precipitation data of close meteorological stations were utilized. In addition, soil temperature and moisture parameters were analyzed using an on-site measuring device. Furthermore, canopy parameters—namely LAI, LT, CO, and GF—were determined using a hemispherical photographing procedure and image processing–analysis methodology. Moreover, the LAI of the meadow cover was determined using an on-site analysis device. The maximum LAI, with mean values of 3.69 m² m⁻² and 2.54 m² m⁻², occurred in late May (DOY: 142) within the forest canopies of the interior parts and the patch edge, respectively. On the other hand, the maximum LAI with a mean value of 2.77 m² m⁻² occurred again in late May within the meadow field. On the contrary, during the same period, the lowest percentages were observed for LT and CO, each at 5%, and for GF with 0.5% within the interior parts of the forest patch. However, their lowest percentages were 23% and 16%, respectively, within the forest patch edge. For that late May period, the mean soil temperatures were 17.2, 26.0, and 21.0 °C under the forest canopies of the interior parts, the patch edge, and the meadow field, respectively. Meanwhile, their mean soil moistures were 56.4%, 51.6%, and 32.9% when the mean air temperature was 16.2 °C. Definite correlation did not exist between the canopy–vegetation parameters and the soil temperature–moisture values for all the interior parts, for the edge of the multi-story grove forest patch, and for the meadow field. Based on the overall results of this study, there were apparent differences amongst the interior parts, the edge of the forest patch, and the meadow field in terms of both the canopy–vegetation parameters and the soil temperature–moisture values. The multi-story structure of the interior parts and the edge of the forest patch determined the temporal patterns of their canopy–vegetation parameters. This study elucidated ecology, hydrology, and therefore management of narrow forest patches between agricultural areas within rural landscapes. Full article

Shaping or splitting of a Gaussian beam is often desired to optimise laser–material interactions, improving throughput and quality. This can be achieved holographically using liquid crystal-on-silicon spatial light modulators (LC-SLMs). Until recently, maximum exposure has been limited to circa 120 W average power with a Gaussian profile, restricting potential applications due to the non-linear (NL) phase response of the liquid crystal above this threshold. In this study, we present experimental tests of a new SLM device, demonstrating high first-order diffraction efficiency of η = 0.98 ± 0.01 at 300 W average power and a phase range Δφ > 2π at P = 383 W, an exceptional performance. The numerically calculated device temperature response with power closely matches that measured, supporting the higher power-handling capability. Surface modification of mild steel and molybdenum up to P = 350 W exposure is demonstrated when employing a single-mode (SM) fibre laser source. Exposure on mild steel with a vortex beam (m = +6) displays numerous ringed regions with varying micro-structures and clear elemental separation created by the radial heat flow. On molybdenum, with multi-spot Gaussian exposure, both MoO₃ films and recrystallisation rings were observed, exposure-dependent. The step change in device capability will accelerate new applications for this LC-SLM in both subtractive and additive manufacturing. Full article