Search Results (2,437)

This study experimentally investigates various flow field designs for a direct ethanol-based proton exchange membrane (PEM) fuel cell operated at a temperature above the vaporization temperature of water. It expands the designs of flow fields investigated for high-temperature (HT) direct ethanol fuel cells by comparing four designs. It investigates the performance of these designs at various ethanol concentrations and flow rates. A series of polarization, constant current, and impedance spectroscopy experiments were carried out at different combinations of operating conditions. The result shows that all flow fields provide poorer performance at a high ethanol concentration (6 M), regardless of ethanol inlet flow rates. At a low concentration (3 M), the 2-channel spiral flow field exhibits higher cell power output (12–18% higher) with less mass transport loss and charge transfer resistance compared to other flow fields, although it has some voltage instability. As such, it is identified as a promising design, particularly for higher-power applications. The 4-channel serpentine, dual-triangle sandwich, and hybrid flow fields offer similar cell power output (max power: ~23 mW/cm²) and cell potentials. However, the cell potential instability and mass transport losses are higher in the hybrid flow field compared to the other two designs. Thus, it is not as promising a design for ethanol-based HT-PEM fuel cells. Since the dual-triangle has similar performance to the 4-channel serpentine, it could be an alternative to the serpentine for ethanol-based HT-PEM fuel cells. Full article

Developing safe and efficient cryoprotectants is critical for effective cryopreservation in biomedical applications. Inspired by natural antifreeze proteins (AFPs), a series of linear and star-shaped peptoids featuring isopropanol side chains to mimic the amphiphilic characteristics of threonine were prepared. The effects of chain length and molecular topology on antifreeze properties were systematically investigated. Both ice recrystallization inhibition (IRI) and ice crystal growth suppression improved with increasing chain length, and star-shaped peptoids exhibited superior performance. Notably, the star-shaped peptoid S-(A₆)₃ demonstrated excellent antifreeze activity and low cytotoxicity, highlighting its promise as a novel, non-toxic alternative to conventional cryoprotectants like DMSO. These findings provide valuable insight into the structure-property relationship of peptoids for cryopreservation applications. Full article

Objectives: This study evaluated peripheral nerve stimulation (PNS) as a treatment for vertebra plana fractures, focusing on its impact on pain intensity, physical function, anxiety, depression, fatigue, social role participation, and pain interference. The goal was to assess whether PNS could serve as a minimally invasive alternative for managing pain in patients with severe vertebral fractures. Methods: Four patients with lumbar vertebra plana fractures received PNS implants for 60 days. Pain scores and PROMIS-29 domains (physical function, anxiety, depression, fatigue, social participation, and pain interference) were assessed at 30, 60, 90, 180, and 365 days post-implantation. Data analysis included mean and standard deviation calculations. Results: PNS led to marked improvements in pain-related outcomes. The average pain intensity scores dropped from 8.5 at baseline to 4.25 at one year, and pain interference scores declined from 61.75 to 54.75. Physical function initially decreased but improved from 38.5 at three months to 46.75 at one year. Changes in depression, anxiety, fatigue, and social participation were minimal, reflecting their multifactorial nature and limited response to pain relief alone. Conclusions: This case series suggests that PNS may significantly reduce pain and pain interference while enhancing physical function in patients with vertebra plana fractures. Its sustained benefits highlight PNS as a promising minimally invasive treatment, especially for those ineligible for traditional procedures. However, the limited improvement in psychological and social domains underscores the need for comprehensive care strategies. Further research is warranted to explore the broader role of PNS in managing vertebral fracture pain. Full article

The mechanical limitations of gypsum-based composites necessitate reinforcement strategies to enhance their structural performance. This study investigates the feasibility of integrating 3D-printed polylactic acid (PLA) meshes into gypsum composites through a series of preliminary experiments. Various mesh configurations were tested, including different fiber thicknesses, mesh grid sizes, and single- and double-layer applications. The impact of mesh incorporation on bulk density, ultrasonic pulse velocity (UPV), bending strength, and compressive strength was assessed. The results indicate that the inclusion of PLA meshes had a limited effect on bulk density and led to a slight decrease in UPV values, suggesting increased porosity. Although improvements in mechanical properties were anticipated, most specimens exhibited lower bending and compressive strengths compared to the reference specimen. Among the tested configurations, 2 mm thick meshes demonstrated relatively higher performance, particularly in bending strength, with narrow-mesh aperture yielding better results. However, double-layer mesh applications consistently resulted in lower strength values. These findings highlight the challenges associated with integrating 3D-printed PLA meshes into gypsum composites. While the study provides valuable insights into mesh-based reinforcement, further investigations are required to optimize fiber–matrix interactions and enhance mechanical performance. Future research should explore alternative printing parameters, improved adhesion techniques, and hybrid reinforcement approaches to fully exploit the potential of additive manufacturing in gypsum-based composites. Full article

Background/Objectives: Pancreatic neoplasms, including adenocarcinoma, pancreatic neuroendocrine tumors (pNETs), intraductal papillary mucinous neoplasms (IPMNs), and high-grade cystic lesions, often require surgical resection as a form of curative treatment. However, comorbidities and high-risk features may preclude surgery. Endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) has emerged as a minimally invasive alternative with proven cytoreductive efficacy in solid tumors. This case series evaluates the safety and efficacy of EUS-RFA in patients with various unresectable, non-metastatic pancreatic neoplasms. Methods: A retrospective review was conducted on eight patients who underwent EUS-RFA at our institutions between July 2021 and February 2025. All patients were deemed unsuitable surgical candidates due to comorbidities such as advanced age, cardiovascular disease, renal insufficiency, and COPD or due to patient resistance to surgical intervention. EUS-RFA was performed using a 19-gauge RFA needle (Taewoong Corporation). Follow-up imaging was conducted 3 to 6 months after the completion of RFA treatment. Results: All eight patients demonstrated a good to excellent response in terms of tumor size reduction. The most notable response was observed in a patient with pNET, resulting in complete resolution from 15.6 × 12.0 mm to 0.0 × 0.0 mm after two RFA treatments. Other neoplasms, including pancreatic adenocarcinoma and intraductal papillary mucinous neoplasms (IPMNs), also demonstrated significant reductions. Mild post-procedure complications, including pancreatitis and abdominal pain, were noted in three cases. Conclusions: EUS-RFA is a promising alternative for managing unresectable pancreatic neoplasms in high-risk patients. Our findings support its use across various tumor types with favorable outcomes and minimal complications, reinforcing its role in expanding therapeutic options beyond surgery. Full article

Capture efficiency (CE) is a critical performance parameter for microchannel plates (MCPs), yet its accurate measurement remains challenging. In this study, we propose an innovative method for evaluating the CE of newly fabricated MCPs based on the detection of a photoelectron beam generated by UV light irradiation of a zinc plate. When incident photoelectrons are detected by the MCPs, they produce a series of disordered pulse signals. We demonstrate that the average pulse interval (denoted as Ts) correlates with the number of electrons entering the microchannels, enabling the assessment of CE differences among various MCPs under identical experimental conditions. Additionally, by partially blocking the incident surface to modulate the active area of the MCP, we established a relationship between Ts and active area, providing a means to roughly quantify CE. This method offers a straightforward alternative for assessing MCP performance, with reduced platform requirements and operational complexity. Full article

FRCM (Fabric-Reinforced Cementitious Matrix) composites, while providing an effective alternative to FRP (Fiber-Reinforced Polymer) strengthening systems when epoxy resins cannot be used, typically fail to achieve their full strengthening potential. Research indicates that appropriate mesh anchorage systems can minimize some of the undesirable effects that limit FRCM composite performance. This study investigates the effectiveness of different anchorage systems for PBO (p-Phenylene Benzobis Oxazole) fibers in FRCM composites used for strengthening reinforced concrete slabs. A series of unidirectionally bent RC slabs were tested under four-point bending: an unstrengthened control element, slabs strengthened with PBO-FRCM without anchorage, with bar anchorage (GFRP bar in a groove), and with cord anchorage (PBO cord through the slab). The research focused on analyzing the load–deflection behavior and key strain mechanisms that influence structural performance. The findings indicate that a single layer of PBO-FRCM increases bending capacity, raises yield load, and delays initial cracking. Most significantly, the research reveals substantial differences in composite mesh utilization efficiency. This study confirms that mechanical anchorage, particularly bar anchorage, significantly enhances the effectiveness of PBO-FRCM strengthening systems by delaying composite detachment and allowing for greater utilization of the high-strength fiber material. These results contribute valuable insights for RC slabs using FRCM composite systems and the anchorage of their mesh. Full article

A diode-based rectifier (DR) is an attractive transmission technology for offshore wind farms, which reduces the volume of large bulk platforms. A novel parallel–series DC wind farm based on a distributed DR is proposed, which meets the requirements of high voltage and high power with an isolation capability from other units. The coupling mechanism between a modular multilevel converter (MMC) and a DR has been built, and the coordinate control strategy for the whole system has been proposed based on the MMC triple control targets with intermediate variables. Under the proposed control strategy, the system automatically operates at maximum power point tracking (MPPT). The feasibility of topology and the effectiveness of the control strategy are verified under start-up, power fluctuation, onshore alternating current (AC) fault, and direct current (DC) fault based on the power systems computer-aided design (PSCAD)/electromagnetic transients including direct current (EMTDC) simulation. Full article

As the presence of renewable energy production grows, so does the need to find alternative solutions for long–term energy storage. One solution may be hydrogen, and more generally, power-to-gas systems, which could allow energy storage for longer periods than batteries. However, the problem of hydrogen storage remains a limitation to the deployment of this technology. A possible solution for the hydrogen storage could be metal hydrides. In this work, a power-to-gas system based on a $2.5\mathrm{kW}$ commercial electrolyzer coupled to a pair of AB2-type metal hydride cylinders with a total volume of $4\mathrm{L}$ is studied. A special focus is placed on the electrolyzer power converter. In particular, the current ripple generated on the side connected to the stack and the efficiency of the converter are studied. A series of tests are carried out to verify the behavior of the system with varying types of thermal conditioning of the hydrides. The results show that the converter used is not optimized for the chosen application, and the thermal conditioning influences the hydrogen adsorption rate and thus the electrolyzer’s behavior. Finally, a technique to operate the system at maximum efficiency is proposed. Full article

Background/Objectives: Prostatic artery embolization (PAE) has emerged as a minimally invasive alternative for treating lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH), particularly in high-risk surgical candidates. This study aims to evaluate the efficacy, safety, and clinical outcomes of PAE, combining a retrospective case series with a narrative review of the literature. Methods: A single-center retrospective analysis was conducted on 10 patients aged ≥ 70 years with moderate-to-severe LUTS due to BPH who underwent PAE between January 2021 and January 2024. Inclusion criteria included IPSS > 18, Qmax < 12 mL/s, prostate volume > 45 cc, and resistance to medical therapy. Embolization was performed using 300–500 µm tris-acryl gelatin microspheres via the PErFecTED technique. Follow-up included IPSS, Qmax, prostate volume (PV), PSA levels, and complications. A narrative review of 18 studies (n = 1539 patients) was also conducted to contextualize findings. Results: Technical success was achieved in all patients (100%), and clinical success (IPSS reduction ≥ 50%) in 90%. At 12 months, the following significant improvements were observed: mean IPSS decreased from 24 to 12 (p < 0.0001), Qmax increased from 8.7 to 12.6 mL/s (p < 0.0001), PV reduced from 66.4 to 49.4 cc (p < 0.0001), and PSA from 5.0 to 3.4 ng/mL (p < 0.0001). Outcomes remained stable up to 36 months. Two patients developed transient post-procedural fever; no major complications were recorded. Conclusions: PAE is a safe and effective treatment for LUTS related to BPH, offering durable symptom relief and minimal morbidity, particularly in elderly and comorbid patients. While the evidence supports its role as an alternative to TURP, larger prospective trials are necessary to confirm its long-term efficacy and optimize patient selection. Full article

In a flight test facility twin-aisle cabin demonstrator, a test series was conducted with the objective to investigate cleaning methods for recirculated air. Based on the data, a 3D zonal airflow simulation model of particle spread and cleaning performance was validated with the aim of extrapolating results to arbitrary aircraft cabins. For the tests, particles containing a phi6 bacteriophage, a virus only attacking a specific bacterium and with a similar structure to SARS-CoV-2, was dosed through a breathing head. The particle distribution and infectiveness of the air samples were measured. State-of-the-art HEPA filtering and cleaners based on UV-C and plasma were integrated in the recirculated air path and experimentally investigated. The test results showed the best cleaning performance for the state-of-the-art HEPA filter, while the alternatives showed lower performance levels. It was noted that infectiveness and particle count did not necessarily follow a monotonic function, making the link between these two quantities challenging. Therefore, modeling showed to be able to properly replicate particle distribution in the cabin, while an assumption of infectiveness depending on particle count had to be made. The model could successfully be applied to a single-aisle aircraft cabin geometry. Full article

The formation and spatial uniformity of calcium carbonate (CaCO₃) are critical for evaluating the effectiveness of microbial-induced calcium carbonate precipitation (MICP) in geotechnical applications. In recent years, the single-phase injection method has emerged as a promising alternative to traditional two-phase processes by addressing the issue of uneven CaCO₃ distribution. This study proposes a dual inhibition strategy that delays the mineralization reaction by synergistically lowering pH and temperature, thereby promoting uniform precipitation and enhanced compressive strength in cemented sand columns. A series of experiments, including bacterial growth, aqueous reaction, sand column reinforcement, and microstructural characterization, were conducted. Results show that the minimum pH required for flocculation increases from ~4.5 at 40 °C to ~6.0 at 10 °C. Under dual inhibition, the lag period effectively improved the spatial uniformity of CaCO₃ and enabled complete calcium utilization within 24 h. After four treatment cycles, the CaCO₃ content at 10 °C increased by 53%, and the unconfined compressive strength reached 2.5 MPa, a 50% improvement over the 40 °C condition. XRD analysis confirmed that calcite was the dominant phase (85–90%), accompanied by minor vaterite. These findings demonstrate the adaptability and efficiency of the dual inhibition method across temperature ranges, providing a cost-effective solution for broader engineering applications. Full article

Methane hydrate is a crystalline compound in which methane is trapped within a water lattice under high-pressure, low-temperature conditions. Its presence in oceanic and permafrost sediments makes it a promising alternative energy source, but also a potential contributor to climate change. Accurate in situ detection remains a major challenge due to hydrate’s dispersed occurrence and the limitations of conventional geophysical methods. This study investigates the feasibility of using the associated alpha particle (AAP) technique for the direct detection of methane hydrate. A series of laboratory measurements was conducted on sand-based samples with varying levels of methane hydrate simulant. Using a 14 MeV neutron generator and a LaBr₃ gamma detector, the 4.44 MeV carbon peak was monitored and calibrated against volumetric hydrate saturation. The minimum detection limit (MDL) was experimentally determined to be $(67\pm 25)\%$. Although the result is subject to high uncertainty, it provides a preliminary benchmark for evaluating the method’s sensitivity and highlights the potential of AAP-based gamma spectroscopy for in situ detection, especially when supported by higher neutron flux in future applications. Full article

Nucleopolyhedroviruses of lepidopteran larvae (Alphabaculovirus, Baculoviridae) form the basis for effective and highly selective biological insecticides for the control of caterpillar pests of greenhouse and field crops and forests. Horizontal transmission is usually achieved following the release of large quantities of viral occlusion bodies (OBs) from virus-killed insects. In the present review, I examine the evidence for productive midgut infection in different host species and the resulting transmission through the release of OBs in the feces (frass) of the host. This has been a neglected aspect of virus transmission since it was initially studied over six decades ago. The different host–virus pathosystems vary markedly in the quantity of OBs released in feces and in their ability to contaminate the host’s food plant. The release of fecal OBs tends to increase over time as the infection progresses. Although based on a small number of studies, the prevalence of transmission of fecal inoculum is comparable with that of recognized alternative routes for transmission and dissemination, such as cannibalism and interactions with predators and parasitoids. Finally, I outline a series of predictions that would affect the importance of OBs in feces as a source of inoculum in the environment and which could form the basis for future lines of research. Full article

The rapid advancement of computing power, combined with the ability to collect vast amounts of data, has unlocked new possibilities for industrial applications. While traditional time–domain industrial signals generally do not allow for direct stability assessment or the detection of abnormal situations, alternative representations can reveal hidden patterns. This paper introduces time-shifted maps (TSMs) as a novel method for analyzing industrial data—an approach that is not yet widely adopted in the field. Unlike contemporary machine learning techniques, TSM relies on a simple and interpretable algorithm designed to process data from standard industrial automation systems. By creating clear, visual representations, TSM facilitates the monitoring and control of production process. Specifically, TSMs are constructed from time series data collected by an acceleration sensor mounted on a robot base. To evaluate the effectiveness of TSM, its results are compared with those obtained using classical signal processing methods, such as the fast Fourier transform (FFT) and wavelet transform. Additionally, TSMs are classified using computed correlation dimensions and entropy measures. To further validate the method, we numerically simulate three distinct anomalous scenarios and present their corresponding TSM-based graphical representations. Full article