Oxygen Transport Research Articles

Modeling the Effect of Cell Orientation on the Performance of an Air-Breathing Polymer Electrolyte Fuel Cell with a Columnar Cathode Plate

Air-breathing polymer electrolyte fuel cells (PEMFCs) are expected to play an important role in the development of sustainable portable and mobile devices, such as unnamed aerial vehicles, motorbikes or laptops. In this work, the performance of air-breathing PEMFCs with a columnar cathode plate design is examined by means of a 3D two-phase, non-isothermal model, and compared against experimental data. The results show that the performance is highly influenced by the cell orientation, namely horizontal (material plane perpendicular to gravity) versus vertical (material plane parallel to gravity). Oxygen transport in horizontal cells is mainly dominated by diffusion, leading to oxygen shortage toward the cell center and an inhomogeneous current density distribution. In contrast, oxygen transport in vertical cells is assisted by natural convection, enhancing oxygen transport throughout the cell and increasing the current density homogeneity. Water saturation is preferentially accumulated close to the cell center, being larger in horizontal cells due to the lower water removal rate of the cathode plate.

Foodborne iron overload induces oxidative stress and causes mitochondrial damage in the liver of grass carp (Ctenopharyngodon idellus)

Iron is essential to biological processes such as energy metabolism and oxygen transport. However, excessive iron can cause iron overload and ultimately result in tissue damage. To date, the damage mechanism of foodborne iron overload in aquatic animals is still unclear. This study used grass carp (Ctenopharyngodon idellas) as the research subject to establish a chronic iron overload model by feeding diets with different iron levels, and combined in vitro experiments to investigate the mechanisms of iron overload-induced damage. The growth performance and liver HE staining indicated that a high‑iron diet led to decreased growth in grass carp, accompanied by hepatic iron deposition. ELISA and qRT-PCR analysis data revealed that a high‑iron diet disrupted the antioxidant balance and modulated the expression of genes associated with iron metabolism. CCK-8 determination results revealed that treatment of L8824 cells with ferri ammonii citras (FAC) resulted in iron overload, led to disruption of iron metabolism and enhanced the intracellular production of reactive oxygen species (ROS), and caused lipid peroxidation. Furthermore, qRT-PCR analysis results showed that the treatment of L8824 cells with FAC resulted in a significant up-regulation of genes associated with antioxidant, apoptosis, and necrosis pathways, and increased the rate of apoptosis. In addition, fluorescence microscopy observation and mitochondrial DNA detection data showed that excess iron could increase the iron accumulation in mitochondria and the production of mtROS, reduce the mitochondrial membrane potential, and finally cause mitochondria damage. In conclusion, our research offers invaluable insights that iron overload leads to disrupted intracellular iron pool stability, causing mitochondrial damage and oxidative stress, eventually causing cell death.

Mathematical model of oxygen minimum zones in the vertical distribution of oxygen in the ocean.

Processes determining the amount and spatial distribution of dissolved oxygen in the ocean have been a focus of intense research over the last two decades. Anomalies known as Oxygen Minimum Zones (OMZs) have been attracting growing attention, in particular because their growth is believed to be a result of the global environmental change. Comprehensive understanding of factors contributing to and/or controlling the emergence and evolution of OMZs is still lacking though. OMZs are usually thought to result from an interplay between the oxygen transport through the water column from the ocean surface and variable oxygen solubility at different water temperature. In this paper, we suggest a different, novel mechanism of the OMZ formation relating it to the oxygen production in phytoplankton photosynthesis in a stratified ocean. We consider a simple, conceptual model of the coupled phytoplankton-oxygen dynamics and show that the model predictions are in qualitative agreement with some relevant field observations.

Effect of GDL Structure and Operating Conditions on PEMFC Performance and Liquid Water Removal

Gas diffusion layers (GDLs) in proton exchange membrane fuel cells (PEMFCs) are responsible for diffusion of reactant gases into the catalyst layers, current collection and the removal of produced water. An accumulation of generated liquid water within the GDL, known as flooding, impedes the supply of reactant gas and results in the increase of concentration overpotential. Therefore, understanding of oxygen transport and produced water removal characteristics is required to enhance cell performance. The objective of this study is to investigate the effect of GDL structure and operation conditions on PEMFC performance and liquid water removal, with a particular focus on comparing a novel GDL to a conventional GDL. The results of a simultaneous evaluation of cell performance and liquid water behavior in the GDLs by means of X-ray imaging under operational conditions are presented.

Water Permeability and Oxygen Transport Resistance of Hydrophilic and Hydrophobic Composite Microporous Layer Coated Gas Diffusion Layer

Enhancing water management to mitigate the performance impact of humidity fluctuations is crucial in PEFC applications. A novel microporous layer (MPL) incorporated with both hydrophilic and hydrophobic properties, applied to the gas diffusion layer (GDL), has been developed and demonstrated to enhance robustness under varying humidity levels. This study utilized water permeability test results to analyze the composite MPL, distinguishing between hydrophobic and hydrophilic absolute permeability ratios. By elucidating these ratios, insights into their roles in liquid water distribution and oxygen transport resistance were gained, distinguishing the composite MPL from conventional hydrophobic and hydrophilic MPLs. Ultimately, the performance of the composite MPL under high and low humidity conditions highlighted its robustness across diverse humidity environments.

Water Permeability and Oxygen Transport Resistance of Hydrophilic and Hydrophobic Composite Microporous Layer Coated Gas Diffusion Layer

Enhancing water management to mitigate the performance impact of humidity fluctuations is crucial in PEFC applications. A novel microporous layer (MPL) incorporated with both hydrophilic and hydrophobic properties, applied to the gas diffusion layer (GDL), has been developed and demonstrated to enhance robustness under varying humidity levels. This study utilized water permeability test results to analyze the composite MPL, distinguishing between hydrophobic and hydrophilic absolute permeability ratios. By elucidating these ratios, insights into their roles in liquid water distribution and oxygen transport resistance were gained, distinguishing the composite MPL from conventional hydrophobic and hydrophilic MPLs. Ultimately, the performance of the composite MPL under high and low humidity conditions highlighted its robustness across diverse humidity environments.

Effect of GDL Structure and Operating Conditions on PEMFC Performance and Liquid Water Removal

Gas diffusion layers (GDLs) in proton exchange membrane fuel cells (PEMFCs) are responsible for diffusion of reactant gases into the catalyst layers, current collection and the removal of produced water. An accumulation of generated liquid water within the GDL, known as flooding, impedes the supply of reactant gas and results in the increase of concentration overpotential. Therefore, understanding of oxygen transport and produced water removal characteristics is required to enhance cell performance. The objective of this study is to investigate the effect of GDL structure and operation conditions on PEMFC performance and liquid water removal, with a particular focus on comparing a novel GDL to a conventional GDL. The results of a simultaneous evaluation of cell performance and liquid water behavior in the GDLs by means of X-ray imaging under operational conditions are presented.

Toxic Effects of Cadmium Exposure on Hematological and Plasma Biochemical Parameters in Fish: A Review.

Cadmium (Cd) is a non-essential trace element that poses significant toxic effects on fish. This review focuses on hematological and plasma biochemical parameters as key indicators of fish health under Cd exposure. Hematological parameters, such as red blood cell (RBC) count, hemoglobin (Hb) concentration, and hematocrit (Ht), were selected for their critical role in oxygen transport and their sensitivity to Cd-induced disruptions, which often result in anemia and impaired oxygen delivery to tissues. Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) provide further insights into erythropoiesis and hemoglobin synthesis, both of which are essential for assessing Cd toxicity. Plasma biochemical parameters, including calcium, magnesium, glucose, cholesterol, total protein, and liver enzymes such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP), are crucial for understanding ionic balance, metabolic regulation, and organ function, especially in fish exposed to Cd. These biomarkers offer a comprehensive view of the physiological stress and organ damage caused by Cd toxicity. This review synthesizes literature findings on the toxic effects of Cd on these parameters. It also discusses potential mitigation strategies, including dietary supplementation with antioxidants and trace elements, to counteract the harmful effects of Cd exposure.

Study on heat and mass transfer behavior of coupled electrochemical reaction in porous structure of proton exchange membrane fuel cell

Proton exchange membrane fuel cell (PEMFC) is widely used in transportation, aviation and energy storage due to its unique advantages. Improving the performance of fuel cells depends largely on effective hydrothermal management. In this work, a multi-physical field coupling model based on the lattice Boltzmann method (LBM) is established to analyze the oxygen transport, liquid water transport, heat transfer and electrochemical reaction, mainly considering the difference between the overpotential of the cell and the surface wettability of the structure. The results show that the overpotential is closely related to the reaction process. The rate of water production is significantly accelerated by increasing the overpotential, and the breakage and merging of water clusters are observed. The increase of overpotential will lead to more energy loss in the form of heat, thus increasing the heat production. Enhancing the hydrophobicity of the structure has a positive effect on the performance of the fuel cell, and the possibility of local hot spots in the low-hydrophobic structure is greater. It is feasible to improve water management and fuel cell performance through wettability design.

Anionic and cationic co-doping to enhance the oxygen transport property of Bi0.5Sr0.5FeO3-δ as a high-performance air electrode for reversible solid oxide cells

Reversible solid oxide cells (RSOCs) have attracted considerable interest due to their efficient energy conversion. However, the low catalytic activity of air electrodes limits the application of RSOCs. Bi0.5Sr0.5Fe0.9Ta0.1O3-δ developed in our previous work exhibits a comparatively desirable performance and is expected to be further optimized. Herein, a novel strategy of anionic F and cationic Ta co-doped Bi0.5Sr0.5Fe0.9Ta0.1O3-δ-xFx (x = 0, 0.05, 0.10, 0.15, denoted as, BSFTF0, BSFTF5, BSFTF10, BSFTF15) materials are obtained to enhance the oxygen transport property of Bi0.5Sr0.5FeO3-δ for RSOCs. The polarization resistance (Rp) of BSFTF10 (0.017 Ω cm2) decreases by 66 % compared with that of BSFTF0 (0.051 Ω cm2) at 800 °C. In fuel cell mode, the single cell with BSTF10 reaches the maximum power density of 908 mW cm−2, which is approximately 72 % higher than the only Ta-doped BSFTF0 (527 mW cm−2) at 800 °C. In electrolysis mode, the single cell with BSFTF10 exhibits a high electrolysis current density of 1679 mA cm−2, indicating an approximately 90 % increase compared to that of BSFTF0 at 800 °C and 1.5 V with 70 % CO2-30 % CO feed gas. The bulk chemical diffusion (Dchem) of BSFTF10 is up to 5.12 × 10−4 cm2 s−1, which is 4.3 times higher than that of BSFTF0. The superior oxygen transport property of BSFTF10 is attributed to the high electronegativity of F− (4.0) and low electronegativity of Ta5+(1.8), which may weaken the chemical bonding between B-site ions and O2−, generating more oxygen vacancies and accelerating the rate of oxygen transfer. The results indicate that F and Ta co-doping is an effective strategy to develop a highly catalytically active air electrode for RSOCs featuring oxygen transport properties.

Effects of 12 Weeks of Combined Exercise Training in Normobaric Hypoxia on Arterial Stiffness, Inflammatory Biomarkers, and Red Blood Cell Hemorheological Function in Obese Older Women.

The present study examined the effect of 12-week combined exercise training in normobaric hypoxia on arterial stiffness, inflammatory biomarkers, and red blood cell (RBC) hemorheological function in 24 obese older women (mean age: 67.96 ± 0.96 years). Subjects were randomly divided into two groups (normoxia (NMX; n = 12) and hypoxia (HPX; n = 12)). Both groups performed aerobic and resistance exercise training programs three times per week for 12 weeks, and the HPX group performed exercise programs in hypoxic environment chambers during the intervention period. Body composition was estimated using bioelectrical impedance analysis equipment. Arterial stiffness was measured using an automatic waveform analyzer. Biomarkers of inflammation and oxygen transport (tumor necrosis factor alpha, interleukin 6 (IL-6), erythropoietin (EPO), and vascular endothelial growth factor (VEGF)), and RBC hemorheological parameters (RBC deformability and aggregation) were analyzed. All variables showed significantly more beneficial changes in the HPX group than in the NMX group during the intervention. The combined exercise training in normobaric hypoxia significantly reduced blood pressure (systolic blood pressure: p < 0.001, diastolic blood pressure: p < 0.001, mean arterial pressure: p < 0.001, pulse pressure: p < 0.05) and brachial-ankle pulse wave velocity (p < 0.001). IL-6 was significantly lower in the HPX group than in the NMX group post-test (p < 0.001). Also, EPO (p < 0.01) and VEGF (p < 0.01) were significantly higher in the HPX group than in the NMX group post-test. Both groups showed significantly improved RBC deformability (RBC EI_3Pa) (p < 0.001) and aggregation (RBC AI_3Pa) (p < 0.001). The present study suggests that combined exercise training in normobaric hypoxia can improve inflammatory biomarkers and RBC hemorheological parameters in obese older women and may help prevent cardiovascular diseases.

Infectious and obstetric determinants of anemia among pregnant women in Southwest Ethiopia.

Anaemia, characterized by low red blood cell or haemoglobin levels, impairs oxygen transport in the body and poses a major global public health issue, particularly affecting pregnant women and children. This study focuses on identifying the factors contributing to anaemia among pregnant women receiving antenatal care (ANC) at Mizan-Tepi University Teaching Hospital (MTUTH) in southwest Ethiopia. A hospital-based unmatched case-control study was conducted from July 1 to August 30, 2022, involving 370 pregnant women (90 with anaemia and 280 without). Data collection included questionnaires, laboratory tests (Hgb and stool examination), and anthropometric measurements. SPSS version 21 was used for data analysis, with binary logistic regression identifying factors associated with anaemia. The significance level was set at a p-value <0.05. The study achieved a 100% response rate for both cases and controls. Factors identified as determinants of anaemia among pregnant women included malaria infection (AOR = 7.83, 95% CI: 3.89-15.8), hookworm infection (AOR = 2.73, 95% CI: 1.39-5.34), short birth interval (AOR = 7.11, 95% CI: 3.59-14.2), and history of unsafe abortion (AOR = 5.40, 95% CI: 2.46-11.8). This study found that malaria infection, hookworm infection, birth interval <33 months, and a history of unsafe abortion are factors contributing to anaemia in pregnant women. Strategies such as distributing insecticide-treated bed nets (ITNs) to combat malaria, improving sanitation, anthelmintic drugs, promoting family planning to prevent unwanted pregnancies and unsafe abortions, and providing preconception care can help reduce the incidence of anaemia.

ITRAQ Based Proteomics Reveals the Potential Mechanism of Placental Injury Induced by Prenatal Stress.

Maternal stress experienced during prenatal development is recognized as a significant risk factor for neurodevelopmental and neuropsychiatric disorders across the offspring's lifespan. The placental barrier serves a crucial function in safeguarding the fetus from detrimental exposures during gestation. However, previous investigations have not yet comprehensively elucidated the extensive connections between prenatal stress and the expression of placental proteins. In this study, we used iTRAQ-based quantitative proteomics to elucidate the placental adaptive mechanisms of pregnant rats in response to fear-induced stress. Our results showed that during pregnancy, exposure to fear-induced stress led to a pathological hypercoagulable state in the mother's body. Placental circulation was also disrupted, significantly reducing placental efficiency and blood oxygen saturation in newborn rats. Proteomic analyses showed that most of the DEPs were annotated to the PI3K-Akt and ECM-receptor interaction signaling pathway. In addition, the expressions of CDC37, HSP90β, AKT, p-AKT and p-mTOR were down-regulated significantly in the placenta. Our results demonstrated that prenatal fear-induced stress led to inhibition of the cellular signal transduction of placental PI3K/AKT/mTOR, which affected biological processes such as rRNA processing, translation, protein folding, protein stability, and oxygen transport in the placenta. These abnormalities in biological functions could potentially damage the barrier function of the placenta and thereby result in abnormal development in the offspring.

A microscopic oxygen transport model for ultra-high dose rate radiotherapy in vivo: The impact of physiological conditions on FLASH effect.

Ultra-high dose rate irradiation (≥40Gy/s, FLASH) has been shown to reduce normal tissue toxicity, while maintaining tumor control compared to conventional dose-rate radiotherapy. The radiolytic oxygen (O2) depletion (ROD) resulting from FLASH has been proposed to explain the normal tissue protection effect; however, in vivo experiments have not confirmed that FLASH induced global tissue hypoxia. Nonetheless, the experiments reported are based on volume-averaged measurement, which have inherent limitations in detecting microscopic phenomena, including the potential preservation of stem cells niches due to local FLASH-induced O2 depletion. Computational modeling offers a complementary approach to understand the ROD caused by FLASH at the microscopic level. We developed a comprehensive model to describe the spatial and temporal dynamics of O2 consumption and transport in response to irradiation in vivo. The change of oxygen enhancement ratio (OER) was used to quantify and investigate the FLASH effect as a function of physiological and radiation parameters at microscopic scale. We considered time-dependent O2 supply and consumption in a 3D cylindrical geometry, incorporating blood flow linking the O2 concentration ([O2]) in the capillary to that within the tissue through the Hill equation, radial and axial diffusion of O2, metabolic and zero-order radiolytic O2 consumption, and a pulsed radiation structure. Time-evolved distributions of [O2] were obtained by numerically solving perfusion-diffusion equations. The model enables the computation of dynamic O2 distribution and the relative change of OER (δROD) under various physiological and radiation conditions in vivo. Initial [O2] level and the subsequent changes during irradiation determined δROD distribution, which strongly depends on physiological parameters, i.e., intercapillary spacing, ultimately determining the tissue area with enhanced radioresistance. We observed that the δROD/FLASH effect is affected by and sensitive to the interplay effect among physiological and radiation parameters. It renders that the FLASH effect can be tissue environment dependent. The saturation of FLASH normal tissue protection upon dose and dose rate was shown. Beyond ∼60Gy/s, no significant decrease in radiosensitivity within tissue region was observed. In turn, for a given dose rate, the change of radiosensitivity became saturated after a certain dose level. Pulse structures with the same dose and instantaneous dose rate but with different delivery times were shown to have distinguishable δROD thus tissue sparing, suggesting the average dose rate could be a metric assessing the FLASH effect and demonstrating the capability of our model to support experimental findings. On a macroscopic scale, the modeling results align with the experimental findings in terms of dose and dose rate thresholds, and it also indicates that pulse structure can vary the FLASH effect. At the microscopic level, this model enables us to examine the spatially resolved FLASH effect based on physiological and irradiation parameters. Our model thus provides a complementary approach to experimental methods for understanding the underlying mechanism of FLASH radiotherapy. Our results show that physiological conditions can potentially determine the FLASH efficacy in tissue protection. The FLASH effect may be observed under optimal combination of physiological parameters, not limited to radiation conditions alone.

Metabolic and Inflammatory Aspects of Iron Deficiency in Obese

Obesity is a chronic disease with a complex etiology, characterized by a persistent inflammatory state induced by various pro-inflammatory cytokines, including interleukin-6. This condition leads to increased production of hepcidin, a protein hormone responsible for regulating iron homeostasis. Hepcidin's primary function is to inhibit iron absorption by enterocytes, the cells lining the small intestine. Symptoms of iron deficiency, which is crucial for oxygen transport, energy production, and immune system support, can be varied and often nonspecific, such as general weakness, pallor, or concentration difficulties, potentially prolonging the diagnostic process. This article aims to analyze the relationship between obesity and iron deficiency in the metabolic context. Obesity, being one of the most prevalent health issues of the modern world, is associated with numerous complications, including disturbances in iron metabolism. Iron deficiency in obese individuals can lead to anemia, reduced physical performance, and cognitive impairments. Traditional treatment methods for this micronutrient deficiency involve supplementation. However, supplementation shows reduced efficacy in overweight and obese individuals, likely due to elevated hepcidin levels. A more effective approach should include interventions targeting not only the supplementation of the missing micronutrient but also weight reduction.

PSLBII-3 Influence of iron supplementation on insulin and glucose dynamics in horses

Abstract Iron is an essential micromineral involved in various physiological functions such as oxygen transport. The National Research Council’s Nutrient Requirements of Horses has iron requirements set at 400 mg iron daily for a 500 kg horse at maintenance; however, a survey found that Thoroughbreds consumed well over the daily requirement at 3,900 mg of iron from hay and grain alone. Additionally, a previous study has found a correlation between hyperinsulinemia and increased ferritin, an indicator of iron body stores. Therefore, the objective of the present study was to determine the effects of iron supplementation on body iron stores as well as insulin and glucose dynamics. It was hypothesized that iron supplementation would influence body iron stores and insulin and glucose responses. Mixed-breed geldings [n = 12; 558.9 ± 74.4 kg body weight (BW)] were housed individually for the study. Horses were fed 2% of their BW in grass hay and an iron-free vitamin mineral supplement, consuming an average of 600 mg of iron daily for the first 28 d (Hay Phase). Horses were then assigned to continue on the hay diet (CTRL; n = 4) or an iron-supplemented diet (IRON; n = 8), in which an oral iron supplement was given daily in the form of ferrous sulfate, with IRON horses consuming an average of 4,000 mg of iron daily for 28 d (Supplement Phase). Oral sugar tests (OSTs) were performed at the beginning of the study as well as the end of each phase, using a 0.45 mL/kg of BW Karo Light Syrup dose to determine insulin response, with jugular venous samples taken prior to the dose and 60 min after. All statistical analysis was performed in GraphPadPrism Version 10.2.0 (GraphPad Software, Boston, MA), using analysis of variance for repeated measures and correlation analysis. All OSTs throughout the study had a significant time effect (P &amp;lt; 0.05) for both insulin and glucose. There was a time X treatment trend (P = 0.1) for insulin during the Supplement Phase and when using multiple comparisons, insulin response was significantly greater (P &amp;lt; 0.0007) at 0 versus 60 min in IRON horses. Although there was no correlation found between 60-min insulin and ferritin concentrations in both IRON and CTRL horses, mean ± SD insulin and ferritin in the IRON group were 23.6 ± 10 uU/mL and 570 ± 195.8 ng/mL, respectively, while in the CTRL group these were 12.7 ± 2.9 uU/mL and 453 ± 31.1 ng/mL, respectively. In conclusion, iron supplementation with an inorganic form at 10 times the daily requirement appears to result in increased insulin responses as well as body iron stores. Further research needs to determine if feeds naturally enriched in iron impact glucose metabolism.

169 Vitamin and mineral supplementation to gestating beef heifers: Fetal physiology and metabolic programming

Abstract Vitamins and minerals have key roles in hormone production and action, enzyme activity, tissue synthesis, oxygen transport, and energy production. These micronutrients are efficiently transferred from the dam to the fetus during gestation to be partitioned for metabolic use and stored as postnatal mineral reserves. Maternal nutrient intake is one of the main factors that influence the availability of vitamins and minerals to the fetus. Thus, an inadequate supply of these critical nutrients can have a long-lasting impact on offspring growth and health. Evidence suggests that biological processes regulating normal growth, development, and nutrient utilization are programmed in utero, even during the earliest developmental stages. Therefore, there is a critical need to evaluate the effects of micronutrient supplementation during gestation on fetal physiology and metabolic programming. Our research group has developed research models examining the impact of maternal vitamin and mineral supplementation (VTM, supplemented vs. NoVTM, not supplemented) during the periconceptual period or throughout gestation in beef heifers. A metabolomic analysis revealed that metabolites in the oxidative phosphorylation pathway were more abundant in the liver of fetuses from VTM than NoVTM dams, suggesting that a greater supply of micronutrients during the periconceptual period and first trimester of pregnancy may positively modulate mitochondrial energy metabolism in offspring. These changes in the abundance of metabolites suggested physiological adaptations to meet fetal metabolic needs. Further, high-resolution respirometry analysis revealed greater efficiency of energy utilization in small intestinal samples of neonatal calves from VTM dams. In fact, VTM offspring were heavier from weaning to breeding phase than NoVTM offspring, suggesting that maternal nutrition affects physiological mechanisms in utero that modulate offspring energetics and efficiency of nutrient utilization in the postnatal period. Furthermore, we reported increased concentrations of histidine, aspartate, and 12 out of 14 neutral amino acids in the allantoic fluid of VTM-supplemented dams. Finally, genes involved with amino acid transport in fetal liver were upregulated in response to VTM supplementation, highlighting the intricate relationship between maternal and fetal nutrition. Vitamin and mineral supplementation were also associated with changes in gene expression, biological processes and pathways in placental tissue at d 83 of gestation. We observed an upregulation of genes in the calcium signaling and cyclic guanosine monophosphate (CGMP)-PKG signaling pathways in response to micronutrient supplementation. Calcium-mediated systems may modulate cell proliferation and steroidogenic activity in bovine placentomes, while CGMP-PKG plays a key role in vascular homeostasis. Placental blood vessel vascularity at term was indeed increased in heifers supplemented throughout gestation, emphasizing the importance of micronutrient supplementation beyond early pregnancy. Altogether, our findings suggest that vitamin and mineral supplementation in the periconceptual period and during gestation play a pivotal role in fetal metabolic programming with consequences extending to the postnatal period.

Effect of upper body venoarterial ECMO on systemic hemodynamics and oxygenation: A computational study

BackgroundThis study seeks to quantify the effects of upper body veno-arterial extracorporeal membrane oxygenation (VA ECMO) on the anatomical distribution of oxygen delivery in the setting of hypoxic respiratory failure and provide new insights that will guide clinical use of this support strategy to bridge patients to lung transplant. MethodsEmploying a patient-specific vascular geometry and a quantitative model of oxygen transport, computational simulations were performed to determine hemodynamics and oxygen delivery in the ascending and descending aorta, left and right coronary arteries, and great vessels during upper body VA ECMO support. Oxygen content in ECMO circuit blood flow was varied while considering different degrees of lung failure severity. Using lumped parameter models to dynamically apply perfusion boundary conditions, hemodynamic parameters and oxygen content were analyzed to assess the effect of ECMO supply titration. ResultsThe results emphasize the importance of anatomical distribution for tissue oxygen delivery in severe lung failure, with ECMO-derived flow primarily augmenting oxygen content in specific vascular beds. They also demonstrate that although cannulating the subclavian artery can enhance cerebral oxygen delivery, its ability to ensure sufficient oxygen delivery to the coronary circulation seems to be comparatively restricted. ConclusionsThe oxygen delivery to a specific vascular area is primarily determined by the oxygen content in the source of perfusion. Caution is advised with upper body VA ECMO for patients with hypoxic respiratory failure and right ventricle dysfunction, due to potential coronary ischemia. Management of these patients is challenging due to disease progression and organ availability uncertainties.

Enhancement of oxygen flux through Nb-doped La0.4Sr0.6FeO3-δ ceramic hollow fiber membranes by Fe exsolution

In recent years, numerous studies have focused on the use of mixed ionic-electronic conducting oxides for coupled oxygen separation and catalytic reactions in membrane reactors. A promising strategy for the efficient fabrication of oxygen separation membranes involves modification of the membrane surface via exsolved metal nanoparticles decoration. Here, we present a detailed characterization of the structural and transport properties of a novel membrane material La0.4Sr0.6Fe0.95Nb0.05O3−δ (LSFNb5). The exsolution of Fe nanoparticles was observed after heating of LSFNb5 in a reducing atmosphere (5 % Н2/Ar) and was confirmed by X-ray diffraction analysis, Mössbauer spectroscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The formation of Fe nanoparticles on the surface of LSFNb5 hollow fiber membrane in the reduction process leads to the enhancement of oxygen fluxes and reduces the apparent activation energy. Kinetic parameters for oxygen transport through LSFNb5 hollow fiber membrane estimated using two different models, are in good agreement with the experimental results. Furthermore, LSFNb5 hollow fiber membrane demonstrates stable performance both before and after surface treatment.

Comprehensive Analysis of the Gradient Porous Transport Layer for the Proton-Exchange Membrane Electrolyzer.

A reasonable porous transport layer (PTL) is crucial to decreasing the mass-transfer loss in proton-exchange membrane water electrolyzers (PEMWEs). In this study, it was experimentally demonstrated that the gradient porosity PTL is beneficial in improving the performance of electrolyzers. The research comprehensively investigates the impact of gradient porosity PTL structures on the performance of the PEMWE, considering mass transfer and interfacial contact. It offers insights into the two-phase (oxygen-water) flow transport mechanisms within the PTLs using a 2D numerical model based on the actual PTL geometry. At the microscopic level, it analyzes how the interfacial contact impacts proton and electron transport mechanisms, affecting not only the contact resistance but also the number of effective catalytic sites for the oxygen evolution reaction. Experimental results demonstrate that the cis-gradient porosity PTL leads to a performance enhancement of 9.3% at 2.2 A/cm2. Numerical simulations reveal that the drivers of oxygen transport include the surface tension of the fibers and the pressure drop influenced by the local PTL porosity. Further analysis indicates that the lower oxygen saturation in the bottom region of the PTL with cis-gradient porosity favors a lower oxygen coverage area in the catalyst layers (CL) since the narrower pore space and higher capillary pressure increase the number of water flow paths into the CL. Overall, this study provides valuable insights for designing high-performance PTLs for use in electrolyzers.