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Search Results (424)

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Keywords = high loaded quality factor

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24 pages, 1396 KiB  
Article
Design of Experiments Leads to Scalable Analgesic Near-Infrared Fluorescent Coconut Nanoemulsions
by Amit Chandra Das, Gayathri Aparnasai Reddy, Shekh Md. Newaj, Smith Patel, Riddhi Vichare, Lu Liu and Jelena M. Janjic
Pharmaceutics 2025, 17(8), 1010; https://doi.org/10.3390/pharmaceutics17081010 (registering DOI) - 1 Aug 2025
Abstract
Background: Pain is a complex phenomenon characterized by unpleasant experiences with profound heterogeneity influenced by biological, psychological, and social factors. According to the National Health Interview Survey, 50.2 million U.S. adults (20.5%) experience pain on most days, with the annual cost of prescription [...] Read more.
Background: Pain is a complex phenomenon characterized by unpleasant experiences with profound heterogeneity influenced by biological, psychological, and social factors. According to the National Health Interview Survey, 50.2 million U.S. adults (20.5%) experience pain on most days, with the annual cost of prescription medication for pain reaching approximately USD 17.8 billion. Theranostic pain nanomedicine therefore emerges as an attractive analgesic strategy with the potential for increased efficacy, reduced side-effects, and treatment personalization. Theranostic nanomedicine combines drug delivery and diagnostic features, allowing for real-time monitoring of analgesic efficacy in vivo using molecular imaging. However, clinical translation of these nanomedicines are challenging due to complex manufacturing methodologies, lack of standardized quality control, and potentially high costs. Quality by Design (QbD) can navigate these challenges and lead to the development of an optimal pain nanomedicine. Our lab previously reported a macrophage-targeted perfluorocarbon nanoemulsion (PFC NE) that demonstrated analgesic efficacy across multiple rodent pain models in both sexes. Here, we report PFC-free, biphasic nanoemulsions formulated with a biocompatible and non-immunogenic plant-based coconut oil loaded with a COX-2 inhibitor and a clinical-grade, indocyanine green (ICG) near-infrared fluorescent (NIRF) dye for parenteral theranostic analgesic nanomedicine. Methods: Critical process parameters and material attributes were identified through the FMECA (Failure, Modes, Effects, and Criticality Analysis) method and optimized using a 3 × 2 full-factorial design of experiments. We investigated the impact of the oil-to-surfactant ratio (w/w) with three different surfactant systems on the colloidal properties of NE. Small-scale (100 mL) batches were manufactured using sonication and microfluidization, and the final formulation was scaled up to 500 mL with microfluidization. The colloidal stability of NE was assessed using dynamic light scattering (DLS) and drug quantification was conducted through reverse-phase HPLC. An in vitro drug release study was conducted using the dialysis bag method, accompanied by HPLC quantification. The formulation was further evaluated for cell viability, cellular uptake, and COX-2 inhibition in the RAW 264.7 macrophage cell line. Results: Nanoemulsion droplet size increased with a higher oil-to-surfactant ratio (w/w) but was no significant impact by the type of surfactant system used. Thermal cycling and serum stability studies confirmed NE colloidal stability upon exposure to high and low temperatures and biological fluids. We also demonstrated the necessity of a solubilizer for long-term fluorescence stability of ICG. The nanoemulsion showed no cellular toxicity and effectively inhibited PGE2 in activated macrophages. Conclusions: To our knowledge, this is the first instance of a celecoxib-loaded theranostic platform developed using a plant-derived hydrocarbon oil, applying the QbD approach that demonstrated COX-2 inhibition. Full article
(This article belongs to the Special Issue Quality by Design in Pharmaceutical Manufacturing)
17 pages, 319 KiB  
Article
Research on Pathways to Improve Carbon Emission Efficiency of Chinese Airlines
by Liukun Zhang and Jiani Zhao
Sustainability 2025, 17(15), 6826; https://doi.org/10.3390/su17156826 - 27 Jul 2025
Viewed by 249
Abstract
As an energy-intensive industry, the aviation sector’s carbon emissions have drawn significant attention. Against the backdrop of the “dual carbon” goals, how to enhance the carbon emission efficiency of airlines has become an urgent issue to be addressed for both industry development and [...] Read more.
As an energy-intensive industry, the aviation sector’s carbon emissions have drawn significant attention. Against the backdrop of the “dual carbon” goals, how to enhance the carbon emission efficiency of airlines has become an urgent issue to be addressed for both industry development and low-carbon targets. This paper constructs an evaluation system for the carbon emission efficiency of airlines and uses the SBM-DDF model under the global production possibility set, combined with the bootstrap-DEA method, to calculate the efficiency values. On this basis, the fuzzy-set qualitative comparative analysis method is employed to analyze the synergistic effects of multiple influencing factors in three dimensions: economic benefits, transportation benefits, and energy consumption on improving carbon emission efficiency. The research findings reveal that, first, a single influencing factor does not constitute a necessary condition for achieving high carbon emission efficiency; second, there are four combinations that enhance carbon emission efficiency: “load volume-driven type”, “scale revenue-driven type”, “high ticket price + technology-driven type”, and “passenger and cargo synergy mixed type”. These discoveries are of great significance for promoting the construction of a carbon emission efficiency system by Chinese airlines and achieving high-quality development in the aviation industry. Full article
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18 pages, 1587 KiB  
Article
Management of Mobile Resonant Electrical Systems for High-Voltage Generation in Non-Destructive Diagnostics of Power Equipment Insulation
by Anatolii Shcherba, Dmytro Vinnychenko, Nataliia Suprunovska, Sergy Roziskulov, Artur Dyczko and Roman Dychkovskyi
Electronics 2025, 14(15), 2923; https://doi.org/10.3390/electronics14152923 - 22 Jul 2025
Viewed by 219
Abstract
This research presents the development and management principles of mobile resonant electrical systems designed for high-voltage generation, intended for non-destructive diagnostics of insulation in high-power electrical equipment. The core of the system is a series inductive–capacitive (LC) circuit characterized by a high quality [...] Read more.
This research presents the development and management principles of mobile resonant electrical systems designed for high-voltage generation, intended for non-destructive diagnostics of insulation in high-power electrical equipment. The core of the system is a series inductive–capacitive (LC) circuit characterized by a high quality (Q) factor and operating at high frequencies, typically in the range of 40–50 kHz or higher. Practical implementations of the LC circuit with Q-factors exceeding 200 have been achieved using advanced materials and configurations. Specifically, ceramic capacitors with a capacitance of approximately 3.5 nF and Q-factors over 1000, in conjunction with custom-made coils possessing Q-factors above 280, have been employed. These coils are constructed using multi-core, insulated, and twisted copper wires of the Litzendraht type to minimize losses at high frequencies. Voltage amplification within the system is effectively controlled by adjusting the current frequency, thereby maximizing voltage across the load without increasing the system’s size or complexity. This frequency-tuning mechanism enables significant reductions in the weight and dimensional characteristics of the electrical system, facilitating the development of compact, mobile installations. These systems are particularly suitable for on-site testing and diagnostics of high-voltage insulation in power cables, large rotating machines such as turbogenerators, and other critical infrastructure components. Beyond insulation diagnostics, the proposed system architecture offers potential for broader applications, including the charging of capacitive energy storage units used in high-voltage pulse systems. Such applications extend to the synthesis of micro- and nanopowders with tailored properties and the electrohydropulse processing of materials and fluids. Overall, this research demonstrates a versatile, efficient, and portable solution for advanced electrical diagnostics and energy applications in the high-voltage domain. Full article
(This article belongs to the Special Issue Energy Harvesting and Energy Storage Systems, 3rd Edition)
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39 pages, 1774 KiB  
Review
FACTS Controllers’ Contribution for Load Frequency Control, Voltage Stability and Congestion Management in Deregulated Power Systems over Time: A Comprehensive Review
by Muhammad Asad, Muhammad Faizan, Pericle Zanchetta and José Ángel Sánchez-Fernández
Appl. Sci. 2025, 15(14), 8039; https://doi.org/10.3390/app15148039 - 18 Jul 2025
Viewed by 369
Abstract
Incremental energy demand, environmental constraints, restrictions in the availability of energy resources, economic conditions, and political impact prompt the power sector toward deregulation. In addition to these impediments, electric power competition for power quality, reliability, availability, and cost forces utilities to maximize utilization [...] Read more.
Incremental energy demand, environmental constraints, restrictions in the availability of energy resources, economic conditions, and political impact prompt the power sector toward deregulation. In addition to these impediments, electric power competition for power quality, reliability, availability, and cost forces utilities to maximize utilization of the existing infrastructure by flowing power on transmission lines near to their thermal limits. All these factors introduce problems related to power network stability, reliability, quality, congestion management, and security in restructured power systems. To overcome these problems, power-electronics-based FACTS devices are one of the beneficial solutions at present. In this review paper, the significant role of FACTS devices in restructured power networks and their technical benefits against various power system problems such as load frequency control, voltage stability, and congestion management will be presented. In addition, an extensive discussion about the comparison between different FACTS devices (series, shunt, and their combination) and comparison between various optimization techniques (classical, analytical, hybrid, and meta-heuristics) that support FACTS devices to achieve their respective benefits is presented in this paper. Generally, it is concluded that third-generation FACTS controllers are more popular to mitigate various power system problems (i.e., load frequency control, voltage stability, and congestion management). Moreover, a combination of multiple FACTS devices, with or without energy storage devices, is more beneficial compared to their individual usage. However, this is not commonly adopted in small power systems due to high installation or maintenance costs. Therefore, there is a trade-off between the selection and cost of FACTS devices to minimize the power system problems. Likewise, meta-heuristics and hybrid optimization techniques are commonly adopted to optimize FACTS devices due to their fast convergence, robustness, higher accuracy, and flexibility. Full article
(This article belongs to the Special Issue State-of-the-Art of Power Systems)
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17 pages, 936 KiB  
Article
Improving the Freight Transportation System in the Context of the Country’s Economic Development
by Veslav Kuranovič, Leonas Ustinovichius, Maciej Nowak, Darius Bazaras and Edgar Sokolovskij
Sustainability 2025, 17(14), 6327; https://doi.org/10.3390/su17146327 - 10 Jul 2025
Viewed by 381
Abstract
Due to the recent significant increase in the scale of both domestic and international cargo transportation, the transport sector is becoming an important factor in the country’s economic development. This implies the need to improve all links in the cargo transportation chain. A [...] Read more.
Due to the recent significant increase in the scale of both domestic and international cargo transportation, the transport sector is becoming an important factor in the country’s economic development. This implies the need to improve all links in the cargo transportation chain. A key role in it is played by logistics centers, which in their activities must meet both state (CO2 emissions, reduction in road load, increase in transportation safety, etc.) and commercial (cargo transportation in the shortest time and at the lowest cost) requirements. The objective of the paper is freight transportation from China to European countries, reflecting issues of CO2 emissions, reduction in road load, and increase in transportation safety. Transport operations from the manufacturer to the logistics center are especially important in this chain, since the efficiency of transportation largely depends on the decisions made by its employees. They select the appropriate types of transport (air, sea, rail, and road transport) and routes for a specific situation. In methodology, the analyzed problem can be presented as a dynamic multi-criteria decision model. It is assumed that the decision-maker—the manager responsible for planning transportation operations—is interested in achieving three basic goals: financial goal minimizing total delivery costs from factories to the logistics center, environmental goal minimizing the negative impact of supply chain operations on the environment, and high level of customer service goal minimizing delivery times from factories to the logistics center. The proposed methodology allows one to reduce the total carbon dioxide emission by 1.1 percent and the average duration of cargo transportation by 1.47 percent. On the other hand, the total cost of their delivery increases by 1.25 percent. By combining these, it is possible to create optimal transportation options, effectively use vehicles, reduce air pollution, and increase the quality of customer service. All this would significantly contribute to the country’s socio-economic development. It is proposed to solve this complex problem based on a dynamic multi-criteria model. In this paper, the problem of constructing a schedule of transport operations from factories to a logistics center is considered. The analyzed problem can be presented as a dynamic multi-criteria decision model. Linear programming and the AHP method were used to solve it. Full article
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14 pages, 569 KiB  
Article
Assessing Choline, Carnitine, and Betaine Intake and Their Effects on Trimethylamine N-Oxide Levels: Validation of a Dietary Questionnaire in a Central European Population
by Witold Streb, Anna Olma, Mateusz Pajor, Alex Suchodolski, Wiktoria Staśkiewicz-Bartecka, Anita Stanjek-Cichoracka, Katarzyna Mitręga, Jacek Kowalczyk and Zbigniew Kalarus
Nutrients 2025, 17(14), 2263; https://doi.org/10.3390/nu17142263 - 9 Jul 2025
Viewed by 383
Abstract
Background/Objectives: Trimethylamine N-oxide (TMAO) is implicated in the development of atherosclerosis and cardiovascular diseases. Preventive strategies must recognize the excessive consumption of products rich in choline, carnitine, and betaine, which are substrates essential for TMAO synthesis. The aim of this study was to [...] Read more.
Background/Objectives: Trimethylamine N-oxide (TMAO) is implicated in the development of atherosclerosis and cardiovascular diseases. Preventive strategies must recognize the excessive consumption of products rich in choline, carnitine, and betaine, which are substrates essential for TMAO synthesis. The aim of this study was to develop and validate a dietary questionnaire to assess the consumption of these compounds and investigate the correlation with serum TMAO levels in a Central European population. Methods: A dietary questionnaire was designed based on a literature review identifying foods high in TMAO precursors. The tool was validated in a prospective study with 94 participants. The theoretical relevance and reliability of the tool were assessed using factor analysis and statistical indices. Reproducibility was evaluated in a subgroup of 10 participants who completed the questionnaire a second time 24 h later. The results of the questionnaire helped us to determine factors contributing to serum TMAO levels. Results: The final questionnaire consisted of 15 questions, providing acceptable data quality (KMO = 0.654). Three main dietary factors were detected: (1) the consumption of fish products and legumes (SS loadings = 1.72; 10.78% variance), (2) the consumption of cereal products and root vegetables (SS loadings = 1.61; 10.05% variance), and (3) the consumption of meat (SS loadings = 1.47; 9.22% variance). Conclusions: The validated questionnaire is a useful tool for assessing the intake of TMAO-promoting foods in post-myocardial infarction patients from Central Europe. It may support dietary risk assessment and nutritional counseling in clinical practice, particularly for secondary cardiovascular prevention. Full article
(This article belongs to the Section Nutrition Methodology & Assessment)
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20 pages, 9084 KiB  
Article
Geochemical Assessment of Potentially Toxic Elements in Urban Stream Sediments Draining into the Keban Dam Lake, Turkey
by Hatice Kara
Appl. Sci. 2025, 15(13), 7565; https://doi.org/10.3390/app15137565 - 5 Jul 2025
Viewed by 221
Abstract
The present study investigates the extent and spatial distribution of metal concentration in stream sediments that flow into Keban Dam Lake, Turkey. Sediment samples were analysed for trace and potentially toxic elements (PTEs), including V, Cr, Co, Ni, Cu, Zn, Pb, Tl, Th, [...] Read more.
The present study investigates the extent and spatial distribution of metal concentration in stream sediments that flow into Keban Dam Lake, Turkey. Sediment samples were analysed for trace and potentially toxic elements (PTEs), including V, Cr, Co, Ni, Cu, Zn, Pb, Tl, Th, and U. Enrichment Factor (EF), Contamination Factor (CF), Geo-accumulation Index (Igeo), and Pollution Load Index (PLI) were employed to assess contamination levels. Results reveal that Cr exhibited very high enrichment (EF = 15.95) in downstream urban samples, while Cu and Zn showed high enrichment in samples collected from the middle to lower reaches of the stream, probably indicating anthropogenic contributions. Most other elements, such as Pb, Tl, Th, and U, were within natural background levels. Sediment Quality Guidelines (SQGs) indicate that Cr, Ni, and Cu may pose potential ecological risks, especially in samples from urban-influenced and downstream areas where concentrations exceed the Probable Effect Levels (PEL; Cr: 160 mg/kg, Ni: 42.8 mg/kg, Cu: 108 mg/kg). Multivariate statistical analyses, including Pearson correlation and hierarchical clustering, reveal three distinct geochemical groupings. Among these, the most contaminated cluster—corresponding to midstream and downstream regions—is characterized by elevated Cu and Zn concentrations. Strong correlations among Cu–Zn, Ni–Cu, and Th–U suggest there is a combination of anthropogenic and lithogenic sources for most metals. While most sites showed low to moderate pollution, urban downstream locations exhibited significant metal accumulation, necessitating the region’s continued environmental monitoring and management strategies. Full article
(This article belongs to the Special Issue Ecotoxicology of Trace Elements on Ecosystems)
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17 pages, 845 KiB  
Article
Prediction of Uncertainty Ramping Demand in New Power Systems Based on a CNN-LSTM Hybrid Neural Network
by Peng Yu, Zhuang Cai, Hao Zhang, Dai Cui, Hang Zhou, Ruijia Yu and Yibo Zhou
Processes 2025, 13(7), 2088; https://doi.org/10.3390/pr13072088 - 1 Jul 2025
Viewed by 348
Abstract
Under the background of “dual-carbon”, expanding renewable energy grid integration exacerbates grid net load volatility, and system climbing requirements escalate. In this paper, the problem of uncertain ramping demand prediction caused by net load prediction error in new power systems is investigated. First, [...] Read more.
Under the background of “dual-carbon”, expanding renewable energy grid integration exacerbates grid net load volatility, and system climbing requirements escalate. In this paper, the problem of uncertain ramping demand prediction caused by net load prediction error in new power systems is investigated. First, the total system ramping demand calculation model is constructed, and the effects of deterministic and uncertain ramping demand on the total system ramping demand are analyzed. Secondly, a prediction model based on a CNN-LSTM hybrid neural network is proposed for the uncertain ramp-up demand, which extracts the spatial correlation features of the multi-source influencing factors through the convolutional layer, captures the dynamic evolution law in the time series by using the LSTM layer, and realizes the high-precision point prediction and reliable interval prediction by combining the quantile regression method. Finally, the actual operation data and forecast data of a provincial power grid are used for example verification, and the results show that the proposed model outperformed traditional models (SVM, RF, BPNN) and single deep learning models (CNN, LSTM) in point prediction performance, achieving higher prediction accuracy and validating the effectiveness of the spatio-temporal feature extraction module. In terms of interval prediction quality, compared with the histogram and QRF benchmark models, the proposed model achieves a significant reduction in the average width of the prediction interval, average upward ramp-up demand, and average downward ramp-down demand while maintaining 100% interval coverage. This demand realizes a better balance between prediction economic efficiency and safety, providing more reliable technical support for the precise assessment of uncertain ramp-up demand in new power systems. Full article
(This article belongs to the Section Energy Systems)
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22 pages, 4476 KiB  
Article
Real-Time Model Predictive Control for Two-Level Voltage Source Inverters with Optimized Switching Frequency
by Ariel Villalón, Claudio Burgos-Mellado, Marco Rivera, Rodrigo Zuloaga, Héctor Levis, Patrick Wheeler and Leidy Y. García
Appl. Sci. 2025, 15(13), 7365; https://doi.org/10.3390/app15137365 - 30 Jun 2025
Viewed by 370
Abstract
The increasing integration of renewable energy, electric vehicles, and industrial applications demands efficient power converter control strategies that reduce switching losses while maintaining high waveform quality. This paper presents a Finite-Control-Set Model Predictive Control (FCS-MPC) strategy for three-phase, two-level voltage source inverters (VSIs), [...] Read more.
The increasing integration of renewable energy, electric vehicles, and industrial applications demands efficient power converter control strategies that reduce switching losses while maintaining high waveform quality. This paper presents a Finite-Control-Set Model Predictive Control (FCS-MPC) strategy for three-phase, two-level voltage source inverters (VSIs), incorporating a secondary objective for switching frequency minimization. Unlike conventional MPC approaches, the proposed method optimally balances control performance and efficiency trade-offs by adjusting the weighting factor (λmin). Real-time implementation using the OPAL-RT platform validates the effectiveness of the approach under both linear and non-linear load conditions. Results demonstrate a significant reduction in switching losses, accompanied by improved waveform tracking; however, trade-offs in distortion are observed under non-linear load scenarios. These findings provide insights into the practical implementation of real-time predictive control strategies for high-performance power converters. Full article
(This article belongs to the Special Issue New Trends in Grid-Forming Inverters for the Power Grid)
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28 pages, 2337 KiB  
Review
Narrative Review on the Management of Neck of Femur Fractures in People Living with HIV: Challenges, Complications, and Long-Term Outcomes
by Yashar Mashayekhi, Chibuchi Amadi-Livingstone, Abdulmalik Timamy, Mohammed Eish, Ahmed Attia, Maria Panourgia, Dushyant Mital, Oliver Pearce and Mohamed H. Ahmed
Microorganisms 2025, 13(7), 1530; https://doi.org/10.3390/microorganisms13071530 - 30 Jun 2025
Viewed by 525
Abstract
Neck of femur (NOF) fractures are a critical orthopaedic emergency with a high morbidity and mortality prevalence, particularly in people living with Human Immunodeficiency Virus (PLWHIV). A combination of HIV infection, combined antiretroviral therapy (cART), and compromised bone health further increases the risk [...] Read more.
Neck of femur (NOF) fractures are a critical orthopaedic emergency with a high morbidity and mortality prevalence, particularly in people living with Human Immunodeficiency Virus (PLWHIV). A combination of HIV infection, combined antiretroviral therapy (cART), and compromised bone health further increases the risk of fragility fractures. Additionally, HIV-related immune dysfunction, cART-induced osteoporosis, and perioperative infection risks further pose challenges in ongoing surgical management. Despite the rising global prevalence of PLWHIV, no specific guidelines exist for the perioperative and post-operative care of PLWHIV undergoing NOF fracture surgery. This narrative review synthesises the current literature on the surgical management of NOF fractures in PLWHIV, focusing on pre-operative considerations, intraoperative strategies, post-operative complications, and long-term outcomes. It also explores infection control, fracture healing dynamics, and ART’s impact on surgical outcomes while identifying key research gaps. A systematic database search (PubMed, Embase, Cochrane Library) identified relevant studies published up to February 2025. Inclusion criteria encompassed studies on incidence, risk factors, ART impact, and NOF fracture outcomes in PLWHIV. Data were analysed to summarise findings and highlight knowledge gaps. Pre-operative care: Optimisation involves assessing immune status (namely, CD4 counts and HIV-1 viral loads), bone health, and cART to minimise surgical risk. Immunodeficiency increases surgical site and periprosthetic infection risks, necessitating potential enhanced antibiotic prophylaxis and close monitoring of potential start/switch/stopping of such therapies. Surgical management of neck of femur (NOF) fractures in PLWHIV should be individualised based on fracture type (intracapsular or extracapsular), age, immune status, bone quality, and functional status. Extracapsular fractures are generally managed with internal fixation using dynamic hip screws or intramedullary nails. For intracapsular fractures, internal fixation may be appropriate for younger patients with good bone quality, though there is an increased risk of non-union in this group. Hemiarthroplasty is typically favoured in older or frailer individuals, offering reduced surgical stress and lower operative time. Total hip arthroplasty (THA) is considered for active patients or those with pre-existing hip joint disease but carries a higher infection risk in immunocompromised individuals. Multidisciplinary evaluation is critical in guiding the most suitable surgical approach for PLWHIV. Importantly, post-operative care carries the risk of higher infection rates, requiring prolonged antibiotic use and wound surveillance. Antiretroviral therapy (ART) contributes to bone demineralisation and chronic inflammation, increasing delayed union healing and non-union risk. HIV-related frailty, neurocognitive impairment, and socioeconomic barriers hinder rehabilitation, affecting recovery. The management of NOF fractures in PLWHIV requires a multidisciplinary, patient-centred approach ideally comprising a team of Orthopaedic surgeon, HIV Physician, Orthogeriatric care, Physiotherapy, Occupational Health, Dietitian, Pharmacist, Psychologist, and related Social Care. Optimising cART, tailoring surgical strategies, and enforcing strict infection control can improve outcomes. Further high-quality studies and randomised controlled trials (RCTs) are essential to develop evidence-based guidelines. Full article
(This article belongs to the Section Virology)
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24 pages, 6055 KiB  
Article
Assessment of Remote Sensing Reflectance Glint Correction Methods from Fixed Automated Above-Water Hyperspectral Radiometric Measurement in Highly Turbid Coastal Waters
by Behnaz Arabi, Masoud Moradi, Annelies Hommersom, Johan van der Molen and Leon Serre-Fredj
Remote Sens. 2025, 17(13), 2209; https://doi.org/10.3390/rs17132209 - 26 Jun 2025
Viewed by 381
Abstract
Fixed automated (unmanned) above-water radiometric measurements are subject to unavoidable sky conditions and surface perturbations, leading to significant uncertainties in retrieved water surface remote sensing reflectances (Rrs(λ), sr−1). This study evaluates various above-water Rrs(λ) glint correction [...] Read more.
Fixed automated (unmanned) above-water radiometric measurements are subject to unavoidable sky conditions and surface perturbations, leading to significant uncertainties in retrieved water surface remote sensing reflectances (Rrs(λ), sr−1). This study evaluates various above-water Rrs(λ) glint correction methods using a comprehensive dataset collected at the Royal Netherlands Institute for Sea Research (NIOZ) Jetty Station located in the Marsdiep tidal inlet of the Dutch Wadden Sea, the Netherlands. The dataset includes in-situ water constituent concentrations (2006–2020), inherent optical properties (IOPs) (2006–2007), and above-water hyperspectral (ir)radiance observations collected every 10 min (2006–2023). The bio-optical models were validated using in-situ IOPs and utilized to generate glint-free remote sensing reflectances, Rrs,ref(λ), using a robust IOP-to-Rrs forward model. The Rrs,ref(λ) spectra were used as a benchmark to assess the accuracy of glint correction methods under various environmental conditions, including different sun positions, wind speeds, cloudiness, and aerosol loads. The results indicate that the three-component reflectance model (3C) outperforms other methods across all conditions, producing the highest percentage of high-quality Rrs(λ) spectra with minimal errors. Methods relying on fixed or lookup-table-based glint correction factors exhibited significant errors under overcast skies, high wind speeds, and varying aerosol optical thickness. The study highlights the critical importance of surface-reflected skylight corrections and wavelength-dependent glint estimations for accurate above-water Rrs(λ) retrievals. Two showcases on chlorophyll-a and total suspended matter retrieval further demonstrate the superiority of the 3C model in minimizing uncertainties. The findings highlight the importance of adaptable correction models that account for environmental variability to ensure accurate Rrs(λ) retrieval and reliable long-term water quality monitoring from hyperspectral radiometric measurements. Full article
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16 pages, 3867 KiB  
Article
Ultralow-Resistance High-Voltage Loaded Woven Air Filter for Fine Particle/Bacteria Removal
by Weisi Fan, Sanqiang Wei, Ziyun Zhang, Lulu Shi, Jun Wang, Wenlan Hao, Kun Zhang and Qiuran Jiang
Polymers 2025, 17(13), 1765; https://doi.org/10.3390/polym17131765 - 26 Jun 2025
Viewed by 385
Abstract
Conventional filters for air filtration typically feature compact nonwoven structures, which not only lead to high pressure drop, significant energy consumption, and a decay in filtration efficacy, but are also uncleanable, resulting in substantial pollution upon disposal. In this study, filters with high-voltage [...] Read more.
Conventional filters for air filtration typically feature compact nonwoven structures, which not only lead to high pressure drop, significant energy consumption, and a decay in filtration efficacy, but are also uncleanable, resulting in substantial pollution upon disposal. In this study, filters with high-voltage electrostatic loading capability were developed with a dopamine binding layer to facilitate the establishment of an Ag conductive layer on the surface of ultraloose woven structure fabrics (pore size: 73.7 μm). The high-voltage-loaded woven structure filtration (VLWF) system was constructed with a negative-ion zone, a high-voltage filtration zone, and a grounded filter. The morphological, chemical, and electrical properties of the filters and the filtration performance of the VLWF system were evaluated. The single-pass filtration efficiencies for PM2.5 and E. coli were 67.4% and 97.0%, respectively. Notably, the pressure drop was reduced to 6.2 Pa, and the quality factor reached 0.1810 Pa−1 with no detectable ozone release. After three cycles of ultrasonic cleaning, approximately 58.4% of filtration efficiency was maintained without any increase in air resistance. The removal of PM2.5 and microorganisms by this system was not solely reliant on blocking and electrostatic attraction but may also involve induced repulsion and biostructure inactivation. By integrating the ultraloose woven structure with high-voltage assistance, this VLWF system effectively balanced the requirements for high filtration efficacy and low air resistance. More importantly, this VLWF system provided a cleanable filter model that reduced the pollution associated with conventional disposable filters and lowered costs for customers. Full article
(This article belongs to the Section Polymer Applications)
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32 pages, 11250 KiB  
Article
Novel Dielectric Resonator-Based Microstrip Filters with Adjustable Transmission and Equalization Zeros
by David Espinosa-Adams, Sergio Llorente-Romano, Vicente González-Posadas, José Luis Jiménez-Martín and Daniel Segovia-Vargas
Electronics 2025, 14(13), 2557; https://doi.org/10.3390/electronics14132557 - 24 Jun 2025
Viewed by 477
Abstract
This work presents a comprehensive technological study of dielectric resonator-based microstrip filters (DRMFs), encompassing the design, fabrication, and rigorous characterization of the TE01δ mode. Through systematic coupling analysis, we demonstrate filters featuring novel input–output coupling techniques and innovative implementations of [...] Read more.
This work presents a comprehensive technological study of dielectric resonator-based microstrip filters (DRMFs), encompassing the design, fabrication, and rigorous characterization of the TE01δ mode. Through systematic coupling analysis, we demonstrate filters featuring novel input–output coupling techniques and innovative implementations of both transmission zeros (4-2-0 configuration) and equalization zeros (4-0-2 configuration), specifically designed for demanding space and radar receiver applications, while the loaded quality factor (QL) and insertion loss do not match those of dielectric resonator cavity filters (DRCFs), our solution significantly surpasses conventional microstrip filters (MFs), achieving QL> 3000 compared to typical QL≈ 200 for coupled-line MFs in X-band. The fabricated filters exhibit exceptional performance as follows: input reflection (S11) below −18 dB (4-2-0) and −16.5 dB (4-0-2), flat transmission response (S21), and out-of-band rejection exceeding −30 dB. Mechanical tuning enables precise control of input–output coupling, inter-resonator coupling, cross-coupling, and frequency synthesis, while equalization zeros provide tailored group delay characteristics. This study positions DRMFs as a viable intermediate technology for high-performance RF systems, bridging the gap between conventional solutions. Full article
(This article belongs to the Special Issue Advances in Low Power Circuit and System Design and Applications)
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28 pages, 9836 KiB  
Article
Cascaded H-Bridge Multilevel Converter Topology for a PV Connected to a Medium-Voltage Grid
by Hammad Alnuman, Essam Hussain, Mokhtar Aly, Emad M. Ahmed and Ahmed Alshahir
Machines 2025, 13(7), 540; https://doi.org/10.3390/machines13070540 - 21 Jun 2025
Viewed by 375
Abstract
When connecting a renewable energy source to a medium-voltage grid, it has to fulfil grid codes and be able to work in a medium-voltage range (>10 kV). Multilevel converters (MLCs) are recognized for their low total harmonic distortion (THD) and ability to work [...] Read more.
When connecting a renewable energy source to a medium-voltage grid, it has to fulfil grid codes and be able to work in a medium-voltage range (>10 kV). Multilevel converters (MLCs) are recognized for their low total harmonic distortion (THD) and ability to work at high voltage compared to other converter types, making them ideal for applications connected to medium-voltage grids whilst being compliant with grid codes and voltage ratings. Cascaded H-bridge multilevel converters (CHBs-MLC) are a type of MLC topology, and they does not need any capacitors or diodes for clamping like other MLC topologies. One of the problems in these types of converters involves the double-frequency harmonics in the DC linking voltage and power, which can increase the size of the capacitors and converters. The use of line frequency transformers for isolation is another factor that increases the system’s size. This paper proposes an isolated CHBs-MLC topology that effectively overcomes double-line frequency harmonics and offers isolation. In the proposed topology, each DC source (renewable energy source) supplies a three-phase load rather than a single-phase load that is seen in conventional MLCs. This is achieved by employing a multi-winding high-frequency transformer (HFT). The primary winding consists of a winding connected to the DC sources. The secondary windings consist of three windings, each supplying one phase of the load. This configuration reduces the DC voltage link ripples, thus improving the power quality. Photovoltaic (PV) renewable energy sources are considered as the DC sources. A case study of a 1.0 MW and 13.8 kV photovoltaic (PV) system is presented, considering two scenarios: variations in solar irradiation and 25% partial panel shedding. The simulations and design results show the benefits of the proposed topology, including a seven-fold reduction in capacitor volume, a 2.7-fold reduction in transformer core volume, a 50% decrease in the current THD, and a 30% reduction in the voltage THD compared to conventional MLCs. The main challenge of the proposed topology is the use of more switches compared to conventional MLCs. However, with advancing technology, the cost is expected to decrease over time. Full article
(This article belongs to the Special Issue Power Converters: Topology, Control, Reliability, and Applications)
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14 pages, 1706 KiB  
Communication
Enhancing Fatigue Life of Metal Parts Produced by High-Speed Laser Powder Bed Fusion Through In Situ Surface Quality Improvement
by Daniel Ordnung, Mirko Sinico, Thibault Mertens, Han Haitjema and Brecht Van Hooreweder
J. Manuf. Mater. Process. 2025, 9(7), 207; https://doi.org/10.3390/jmmp9070207 - 20 Jun 2025
Viewed by 343
Abstract
The poor surface quality of the metal parts produced by laser powder bed fusion limits their application in load-bearing components, as it promotes crack initiation under cyclic loadings. Consequently, improving part quality relies on time-consuming surface finishing. This work explores a dual-laser powder [...] Read more.
The poor surface quality of the metal parts produced by laser powder bed fusion limits their application in load-bearing components, as it promotes crack initiation under cyclic loadings. Consequently, improving part quality relies on time-consuming surface finishing. This work explores a dual-laser powder bed fusion strategy to simultaneously improve the productivity, surface quality, and fatigue life of parts with inclined up-facing surfaces made from a novel tool steel. This is achieved by combining building using a high layer thickness of 120 μm with in situ quality enhancement through powder removal and laser remelting. A bending fatigue campaign was conducted to assess the performance of such treated samples produced with different layer thicknesses (60 μm, hull-bulk 60/120 μm, 120 μm) compared to as-built and machined reference samples. Remelting consistently enhanced the fatigue life compared to the as-built reference samples by up to a factor of 36. The improvement was attributed to the reduced surface roughness, the reduced critical stress concentration factors, and the gradually changing surface features with increased lateral dimensions. This led to a beneficial load distribution and fewer potential crack initiation points. Finally, the remelting samples produced with a layer thickness of 120 μm enhanced the fatigue life by a factor of four and reduced the production time by 30% compared to the standard approach using a layer thickness of 60 μm. Full article
(This article belongs to the Special Issue Progress and Perspectives in Metal Laser Additive Manufacturing)
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