Search Results (965)

Tantalum nitride (TaN) is a typical transition metal nitride characterized by a wide range of tunable resistivity. Low-resistance TaN even exhibits a resistivity similar to that of metals. Given that electrical resistance influences secondary electron emission (SEE) behavior, this study investigates the relationship between TaN film resistivity and SEE characteristics. Five TaN films were deposited by varying the N₂ gas flow rate during sputtering. Morphological analyses revealed that the film thicknesses ranged from approximately 197 to 281 nm. X-ray photoelectron spectroscopy (XPS) results indicated that the Ta:N atomic ratio of the films ranged from approximately 0.53 to 0.87. Furthermore, XPS detected non-adsorbed oxygen on the surfaces of the TaN films, and more detailed XPS analysis revealed the formation of TaON compounds on the surfaces due to oxygen exposure. X-ray diffraction patterns confirmed that the TaN films contained two crystal phases: Ta₂N (002) and TaN (200). Sheet resistivity tests showed that the resistivity of the TaN films ranged from 5.67 × 10⁻³ to 2.43 Ω·cm. Furthermore, the lower the Ta:N atomic ratio was, the lower the electrical resistivity of the films became. SEE coefficient (SEEC) showed a clear positive correlation with the films’ electrical resistivity. Specifically, films with lower resistivity exhibited reduced SEEC values. When the N₂ gas flow rate was 16 sccm (N₂:Ar = 16:0), the film exhibited the smallest SEEC (maximum ~1.88); when the N₂ flow rate was 0 sccm (N₂:Ar = 0:16), the film showed the largest SEEC (maximum ~2.25). This research provides valuable references for expanding the application of TaN films in engineering scenarios involving electrical resistivity adjustment and SEE applications. Full article

In solid rocket propulsion systems, overload effects induced by aircraft maneuvers can lead to gas accumulation in the afterburning chamber, resulting in severe localized ablation of thermal insulation layers and significantly compromising overall operational stability. Traditional ablation experimental methods (e.g., oxyacetylene and plasma ablation) exhibit poor correlation with the actual thermal environments in solid rocket ramjets, thereby posing substantial challenges for simulating real operational conditions. To address this issue, an oxygen-kerosene engine-based ablation device was developed. Methodologically, the CEA-optimized oxygen-to-fuel ratio (3.5) enabled authentic combustion simulation, while 3D compressible flow modeling (Ansys Fluent 2020 R2) quantified critical parameters such as chamber pressure and achieved precise control of surface temperature. Ablation experiments were conducted on diverse ablative materials using this device, yielding a maximum error in mass ablation rate of only 5.67%. This demonstrates the high accuracy of the device, which meets the requirements for ablation experiments. This reliable simulator (with an error <6%) provides a validated platform for high-fidelity evaluation of ablation performance in maneuverable solid rocket ramjets. Full article

Background/Objective: Paprika xanthophylls (PXs) have potent antioxidant properties and are believed to improve oxygen delivery (DO₂) efficiency by enhancing red blood cell (RBC) deformability. This study investigated whether PX ingestion improves endurance performance and subsequently enhances cognitive function by improving brain microcirculation. Methods: A crossover design was used to compare the effects of PX ingestion and a control condition in 21 healthy college students (18 males, 3 females). Each participant served as their own control, completing both conditions in a randomized order with a one-month washout period to eliminate any carryover effects. The participants underwent an incremental load test, a constant load test, the Trail Making Test Type B (TMT-B), and the Stroop test (ST). Results: In the incremental tests, the PX group showed a significantly lower heart rate (p = 0.032) and higher exercise efficiency (EE) (p = 0.004). In the constant load test, heart rate was lower (p = 0.020), and EE was higher (p = 0.030). No significant between-group differences were found in the cognitive tests; however, the PX group showed significant improvements in the TMT-B (p = 0.034) and ST interference rate I (p = 0.040). Conclusions: It is speculated that PX intake may improve DO₂ efficiency, which could contribute to the observed enhancements in endurance performance and, in turn, positively affect cognitive function by optimizing the brain’s oxygenation state. However, due to the absence of a placebo control group and unmeasured RBC deformability and cerebral blood flow, as well as a significant male predominance, this study’s results should be interpreted with caution. Full article

The purpose of this study was to design a Pt/TiO₂–ZrO₂ catalytic-based treatment system to remove ethanol and oxygen (O₂) from a gaseous feed stream. The ultimate target application was the conversion of ethanol and O₂ to carbon dioxide (CO₂) and water (H₂O) from a feed stream of CO₂ in a commercial beer brewing operation. Bench-scale reactions were performed at 250 °C and 300 °C, representing two temperatures under practical consideration for a full-scale catalytic reactor. The target gaseous feed stream would be expected to have a relatively low (near-stoichiometric) concentration of O₂, so the effect of O₂ concentration was also studied. On the bench scale, ethanol was completely converted to CO₂ under low flow rate conditions, and the reactions proceeded through volatile and non-volatile reaction intermediates. Results from the bench-scale tests were used to make predictions for designing a pilot-scale catalytic reactor under conditions of high and low O₂ concentration. A pilot-scale reactor was constructed and installed in a commercial brewing facility, and results from testing the pilot-scale reactor are also presented. The pilot-scale system reduced the feed stream ethanol concentrations by 99.9% while concomitantly reducing the O₂ concentrations over the course of a six-day demonstration period without generating unacceptable levels of byproducts. Full article

This manuscript introduces a river segmentation method and explores the impact of human interventions through a long-term study of total nitrogen, total phosphorus, chemical oxygen demand, and biochemical oxygen demand. An indicator linking parameter concentrations to the river’s flow rate was used to assess the development of the examined parameters. The analysis spanned from 2011 to 2022, considering both seasonal and yearly variations. Normal probability plots served as statistical tools to evaluate whether the data followed normal distributions and identify outliers. The proposed segmentation divided the Bahlui River into four segments, each defined by anthropogenic stressors. It was found that, due to human activity, each river segment could be viewed as an “independent” river. This supports the idea that river segments can be analyzed separately as distinct components. The proposed segmentation approach represents an alternative approach in river water quality research, moving from traditional continuous system models to fragmented system analysis, which better reflects the reality of heavily modified river systems. The study’s findings are important for understanding how anthropogenic modifications affect river ecosystem functioning in the long term. Full article

Butyric acid is one of the main volatile fatty acids (VFAs) in Maotai-flavor liquor wastewater (MFLW), and its degradation process exhibits a positive Gibbs free energy, making it prone to accumulation during high-load anaerobic digestion (AD), which can lead to system instability or even failure. In this study, hydrochar (HTC) was prepared from rice husk obtained from distiller’s grains, and butyrate-degrading microbiomes were selectively enriched under acidic conditions with butyric acid as the sole carbon source. Through co-incubation, the butyrate-degrading microbiomes were successfully pre-coupled with HTC, forming a “hydrochar–microbe” composite, which was then applied to the AD of MFLW. The experimental results demonstrated that this composite enhanced system performance. The hydrochar–butyrate pre-coupling group (HBA-C) showed a 15.48% increase in methane yield compared to the control group (CK), with a soluble chemical oxygen demand (sCOD) removal rate of 75.02%, effectively mitigating VFA accumulation. Microbial community analysis indicated higher bacterial and archaeal diversity indices in the HBA-C group. qPCR results showed that the bacterial and archaeal copy numbers in the HBA-C group were 22.06-times and 13.80-times higher than those in the CK group, respectively. Moreover, the relative abundance of the genes for the key enzymes methylmalonyl-CoA carboxyltransferase (EC: 2.1.3.1) and succinate dehydrogenase (EC: 1.3.5.1) was significantly increased, indicating that the “hydrochar–microbe” coupling enhanced carbon flow distribution efficiency and energy metabolism by optimizing metabolic pathways. This study provides an innovative strategy for MFLW treatment and offers practical value for anaerobic digestion optimization and high-strength wastewater management. Full article

The primary objective of the present study is to evaluate the effect of conglomerate microorganisms on nitrification in activated sludge. The present study compares this process with activated-sludge technology to explore the variables that influence the complex biochemical processes taking place in bioreactors. The research under consideration involves monitoring the effectiveness of optimizing the wastewater treatment process using kinetic modeling for the nitrification and denitrification processes. The system is designed to simulate various operating scenarios and adjust process parameters in real time. The nitrification rate demonstrates a 99.03% performance, while the denitrification rate ranges from 19.08% to 91.01%. A substantial correlation has been demonstrated between this variable and the temperature of the treated wastewater. This provides the possibility of accurately assessing the ammonium oxidation potential. Furthermore, kinetic equations facilitate the estimation of parameters that are not typically measured, yet are essential for optimizing operational parameters (e.g., dissolved oxygen levels in the aeration tank, sludge dosage, and influent flow rate). This estimation is crucial for enhancing the effectiveness of the process and attaining the desired or anticipated outcomes. This validation underscores the efficacy of the technology, thereby establishing a foundational framework for subsequent research endeavors. These research efforts are directed towards providing decision-makers and stakeholders with actionable insights. The validation underscores the significance of optimized practices in the context of water resource protection. Moreover, it signifies a substantial advancement in the instrumentation of wastewater treatment plants. Full article

Industrial alkaline water electrolysis systems face challenges in maintaining hydrogen-in-oxygen impurity within safe limits under fluctuating operating conditions. This study aims to characterize the dynamic response of hydrogen-in-oxygen concentration in an industrial 10 kW alkaline water electrolysis test platform (2 Nm³/h hydrogen output at 1.6 MPa and 90 °C) and to identify how operating parameters influence hydrogen-in-oxygen behavior. We systematically varied the cell current, system pressure, and electrolyte flow rate while monitoring real-time hydrogen-in-oxygen levels. The results show that hydrogen-in-oxygen exhibits significant inertia and delay: during startup, hydrogen-in-oxygen remained below the 2% safety threshold and stabilized at 0.9% at full load, whereas a step decrease to 60% load caused hydrogen-in-oxygen to rise to 1.6%. Furthermore, reducing the pressure from 1.4 to 1.0 MPa lowered the hydrogen-in-oxygen concentration by up to 15%, and halving the alkaline flow rate suppressed hydrogen-in-oxygen by over 20% compared to constant conditions. These findings provide new quantitative insights into hydrogen-in-oxygen dynamics and offer a basis for optimizing control strategies to keep gas purity within safe limits in industrial-scale alkaline water electrolysis systems. Full article

Background: Patients undergoing head and neck surgery with free flap reconstruction are at a high risk for postoperative respiratory complications, including hypoxemia. Conventional oxygen therapy (COT) and non-invasive ventilation (NIV) may be poorly tolerated or contraindicated due to anatomical limitations. High-Flow Nasal Cannula (HFNC) therapy represents a promising alternative, offering better humidification, comfort, and oxygenation. Methods: This retrospective single-center study included 50 adult patients admitted to the ICU after head and neck oncologic surgery with flap reconstruction from January 2022 to November 2024. All patients received HFNC immediately after extubation. Hypoxemia was defined as a PaO₂/FiO₂ (P/F) ratio of < 300 mm Hg. The primary outcome was the incidence of postoperative hypoxemia. Secondary outcomes included reintubation rates and patient compliance. Data were collected at 1, 6, 12, and 24 h following HFNC initiation. Results: Out of 59 patients screened, 9 were excluded per predefined criteria. Among the 50 included, only 2 patients (4%) developed hypoxemia, with P/F ratios remaining above 250. No patients required reintubation. The respiratory rate–oxygenation index (ROX index) improved steadily during the first 24 h. HFNC was well tolerated; only three patients required minor adjustments due to discomfort. Conclusions: HFNC use in the immediate postoperative period after head and neck surgery was associated with a low incidence of hypoxemia and no reintubations. These findings suggest that HFNC is a safe and effective strategy for postoperative respiratory support in this high-risk population. Further prospective studies are warranted to confirm the benefit of HFNC in reducing hypoxemia and preventing reintubation in high-risk surgical populations. Full article

Variable-thrust liquid rocket engines are essential for precision landing in deep-space exploration, reusable launch vehicle recovery, high-accuracy orbital maneuvers, and emergency obstacle evasions of space drones. However, with the increasingly complex space missions, challenges remain with the development of different technical schemes. In view of these issues, this paper systematically reviews the technology’s evolution through mechanical throttling, electromechanical precision regulation, and commercial space-driven deep throttling. Then, the development of key variable thrust technologies for liquid rocket engines is summarized from the perspective of thrust regulation and control strategy. For instance, thrust regulation requires synergistic flow control devices and adjustable pintle injectors to dynamically match flow rates with injection pressure drops, ensuring combustion stability across wide thrust ranges—particularly under extreme conditions during space drones’ high-maneuver orbital adjustments—though pintle injector optimization for such scenarios remains challenging. System control must address strong multivariable coupling, response delays, and high-disturbance environments, as well as bottlenecks in sensor reliability and nonlinear modeling. Furthermore, prospects are made in response to the research progress, and breakthroughs are required in cryogenic wide-range flow regulation for liquid oxygen-methane propellants, combustion stability during deep throttling, and AI-based intelligent control to support space drones’ autonomous orbital transfer, rapid reusability, and on-demand trajectory correction in complex deep-space missions. Full article

A computational fluid dynamics (CFD) numerical simulation methodology was implemented to model transient heating processes in steel industry reheating furnaces, targeting combustion efficiency optimization and carbon emission reduction. The effects of oxygen concentration (O₂%) and different fuel types on the flow and heat transfer characteristics were investigated under both oxygen-enriched combustion and MILD oxy-fuel combustion. The results indicate that MILD oxy-fuel combustion promotes flue gas entrainment via high-velocity oxygen jets, leading to a substantial improvement in the uniformity of the furnace temperature field. The effect is most obvious at O₂% = 31%. MILD oxy-fuel combustion significantly reduces NOx emissions, achieving levels that are one to two orders of magnitude lower than those under oxygen-enriched combustion. Under MILD conditions, the oxygen mass fraction in flue gas remains below 0.001 when O₂% ≤ 81%, indicating effective dilution. In contrast, oxygen-enriched combustion leads to a sharp rise in flame temperature with an increasing oxygen concentration, resulting in a significant increase in NOx emissions. Elevating the oxygen concentration enhances both thermal efficiency and the energy-saving rate for both combustion modes; however, the rate of improvement diminishes when O₂% exceeds 51%. Based on these findings, MILD oxy-fuel combustion using mixed gas or natural gas is recommended for reheating furnaces operating at O₂% = 51–71%, while coke oven gas is not. Full article

Streptococcus iniae (S. iniae) is a globally significant aquatic pathogen responsible for severe economic losses in aquaculture. While the S. iniae infection often exhibits distinct seasonal patterns strongly correlated with water temperature, there is limited knowledge regarding the temperature-dependent immune evasion strategies of S. iniae. Our results demonstrated a striking temperature-dependent virulence phenotype, with significantly higher A. latus mortality rates observed at high temperature (HT, 33 °C) compared to low temperature (LT, 23 °C). Proteomic analysis revealed temperature-dependent upregulation of key virulence factors, including streptolysin S-related proteins (SagG, SagH), antioxidant-related proteins (SodA), and multiple capsular polysaccharide (cps) synthesis proteins (cpsD, cpsH, cpsL, cpsY). Flow cytometry analysis showed that HT infection significantly reduced the percentage of lymphocyte and myeloid cell populations in the head kidney leukocytes of A. latus, which was associated with elevated caspase-3/7 expression and increased apoptosis. In addition, HT infection significantly inhibited the release of reactive oxygen species (ROS) but not nitric oxide (NO) production. Using S. iniae cps-deficient mutant, Δcps, we demonstrated that the cps is essential for temperature-dependent phagocytosis resistance in S. iniae, as phagocytic activity against Δcps remained unchanged across temperatures, while NS-1 showed significantly reduced uptake at HT. These findings provide new insights into the immune evasion of S. iniae under thermal regulation, deepening our understanding of the thermal adaptation of aquatic bacterial pathogens. Full article

The availability of detritus is a key factor influencing aquatic biota and can significantly affect decomposition processes. In this study, we investigated how varying quantities of surrounding detritus impact leaf litter decay rates. It was tested in flowing and still-water microcosms to highlight context-dependent effects of surrounding detritus on leaf litter decomposition. To isolate the effect of detritus amount, experiments were conducted in laboratory microcosms simulating lotic and lentic ecosystems, each containing leaf fragments for decomposition assessments. Four detritus quantities were tested, with invertebrates either allowed or restricted from moving among detritus patches. Leaf decomposition rates were influenced by the amount of surrounding detritus, with slower decay observed at higher detritus conditions, regardless of invertebrate mobility. Detritivore distribution responded to both detritus quantity and oxygen availability, showing a preference for high detritus conditions. Additionally, detritus quantity affected microbial activity with a quadratic response, as indicated by leaf respiration rates. Overall, our findings indicate that the amount of surrounding detritus modulates leaf litter decomposition independently of invertebrate density, by influencing oxygen dynamics and, consequently, the activity of biological decomposers. Full article

Brain ischemia is a severe condition caused by reduced cerebral blood flow, leading to the disruption of ion gradients in brain tissue. This imbalance triggers spreading depolarizations, which are waves of neuronal and glial depolarization propagating through the gray matter. Microelectrode arrays (MEAs) are essential for real-time monitoring of these electrophysiological processes both in vivo and in vitro, but their sensitivity and signal quality are critical for accurate detection of extracellular brain activity. In this study, we evaluate the performance of a flexible microelectrode array based on gold-coated zinc oxide nanorods (ZnO NRs), referred to as nano-fMEA, specifically for high-fidelity electrophysiological recording under pathological conditions. Acute mouse brain slices were tested under two ischemic models: oxygen–glucose deprivation (OGD) and hyperkalemia. The nano-fMEA demonstrated significant improvements in event detection rates and in capturing subtle fluctuations in neural signals compared to flat fMEAs. This enhanced performance is primarily attributed to an optimized electrode–tissue interface that reduces impedance and improves charge transfer. These features enabled the nano-fMEA to detect weak or transient electrophysiological events more effectively, making it a valuable platform for investigating neural dynamics during metabolic stress. Overall, the results underscore the promise of ZnO NRs in advancing electrophysiological tools for neuroscience research. Full article

Pre-oxygenation is the key step prior to endotracheal intubation, particularly in a critically ill patient, to prevent life-threatening peri-procedural hypoxemia. This narrative review explores the emerging interest of Non-Invasive Positive Pressure Ventilation (NIPPV) as a pre-oxygenation modality in the intensive care unit (ICU) context. We reviewed data from randomized controlled trials (RCTs) and observational studies published from 2000 to 2024 that compare NIPPV to conventional oxygen therapy and High Flow Nasal Cannula Oxygen (HFNCO). The pathophysiological mechanisms for the successful use of NIPPV, including alveolar recruitment, the decrease of shunting, and the maintenance of functional residual capacity, were reviewed in depth. Existing studies show that NIPPV significantly prolongs the apnea time, reduces the rate of peri-intubation severe hypoxaemia in selected patients and is especially effective for patients with acute hypoxaemic respiratory failure. Nevertheless, appropriate patient selection is still crucial because some diseases can contraindicate or even be harmful with NIPPV. We further discussed the practical aspects of how to use this ventilatory support (the best ventilator settings, which interface, and when to apply it). We lastly discuss unanswered questions and offer suggestions and opportunities for future exploration in guiding the role of NIPPV use in the pre-oxygenation of the critically ill patient requiring emergent airway management. Full article