Partial Oxygen Research Articles

Interpretable machine learning model for early morbidity risk prediction in patients with sepsis-induced coagulopathy: a multi-center study

BackgroundSepsis-induced coagulopathy (SIC) is a complex condition characterized by systemic inflammation and coagulopathy. This study aimed to develop and validate a machine learning (ML) model to predict SIC risk in patients with sepsis.MethodsPatients with sepsis admitted to the intensive care unit (ICU) between March 1, 2021, and March 1, 2024, at Hebei General Hospital and Handan Central Hospital (East District) were retrospectively included. Patients were categorized into SIC and non-SIC groups. Data were split into training (70%) and testing (30%) sets. Additionally, for temporal validation, patients with sepsis admitted between March 1, 2024, and October 31, 2024, at Hebei General Hospital were included. Feature selection was performed using least absolute shrinkage and selection operator (LASSO) regression and multivariate logistic regression. Nine ML algorithms were tested, and model performance was assessed using receiver operating characteristic curve (ROC) analysis, including area under the curve (AUC), calibration curves, and decision curve analysis (DCA). The SHaply Additive Explanations (SHAP) algorithm was used to interpret the best-performing model and visualize key predictors.ResultsAmong 847 patients with sepsis, 480 (56.7%) developed SIC. The random forest (RF) model with eight variables performed best, achieving AUCs of 0.782 [95% confidence interval (CI): 0.745, 0.818] in the training set, 0.750 (95% CI: 0.690, 0.809) in the testing set, and 0.784 (95% CI: 0.711, 0.857) in the validation set. Key predictors included activated partial thromboplastin time, lactate, oxygenation index, and total protein.ConclusionsThis ML model reliably predicts SIC risk. SHAP enhances interpretability, supporting early, individualized interventions to improve outcomes in patients with sepsis.

Pilot-scale partial nitrification and anaerobic ammonium oxidation system for nitrogen removal from municipal wastewater

Partial nitrification has the advantages of saving energy and reducing the need for carbon sources in municipal wastewater treatment. However, for municipal wastewater with low ammonia, start-up and maintenance of partial nitrification is a worldwide challenge. Here we developed a pilot-scale double sludge system consisting of two sequencing batch reactors for partial nitrification (12 m2) and denitrification/anaerobic ammonium oxidation (denitrification/anammox, 8.4 m2) to treat municipal wastewater. Partial nitrification was maintained at no ammonium remaining with a nitrite accumulation rate of 87.7%. This study found that partial nitrification system effluent chemical oxygen demand increased from 24.8 mg L−1 to 64.9 mg L−1 accompanied by transformation from complete nitrification to partial nitrification. In the denitrification/anammox system, the reduction of nitrite to nitrogen required about 40% less carbon consumption than nitrate. High nitrogen removal was achieved with effluent total inorganic nitrogen of 2.7 mg L−1 without carbon addition. This work provided a pilot-scale demonstration of low-carbon high-nitrogen removal.

Suppressing Thermal Conductivity in SrTiO3 by Introducing Oxygen Isotope Disorder.

Transition metal oxides are promising candidates in the field of thermoelectricity, which can convert heat and electricity into each other and realize the efficient utilization of waste energy. For the figure of merit ZT = S2σT/(κe + κl), a lower thermal conductivity is desired for an enhanced ZT, and cation doping is an appropriate way to regulate the thermal transport properties. However, because S, σ, and κe are strongly coupled with each other, cation doping for one parameter modification can generate compensation with others, making regulation more difficult. In this work, we demonstrate the effective engineering of the thermal conductivity of SrTiO3 films by partial oxygen isotope substitution with 18O using a straightforward aftergrowth thermal annealing process. The results show that the isotope disorder promotes the scattering of phonons and generates a nearly 20% decreased thermal conductivity of SrTiO3 films. Our work provides a convenient new route for the design of thermoelectric materials with high ZT values.

Clinical Effects of Traditional Chinese Medicine + Azithromycin in the Treatment of Mycoplasma Pneumonia.

To explore the clinical effect of Traditional Chinese Medicine (TCM) plus azithromycin in the treatment of Mycoplasma pneumonia (MP). This was a retrospective study including the clinical data of 119 patients with MP treated at Taihe County Hospital of Traditional Chinese Medicine from April 2021 to November 2023. According to treatment records, 58 cases were treated with conventional therapy and azithromycin (azithromycin group), and 61 cases were treated with conventional therapy, azithromycin, and Xiaoxianxiong decoction and Weijing decoction and acupoint application (TCM + azithromycin group). The treatment outcomes, levels of inflammatory status indicators before and after treatment, respiratory function status, and incidence of adverse reactions were analyzed between the two groups. The overall effective rate of TCM + azithromycin group was significantly higher than that of azithromycin group (P<0.05). After treatment, the serum C-reactive protein (CRP), procalcitonin (PCT), and white blood cell count (WBC) levels in both groups significantly decreased compared to before treatment, and the TCM + azithromycin group was significantly lower than the azithromycin group (P<0.05). After treatment, partial pressure of carbon dioxide (PaCO2) in both groups significantly decreased compared to before treatment, while oxygen partial pressure (PaO2) and oxygenation index (OI) significantly increased compared to before treatment; Moreover, the TCM + azithromycin group had significantly lower PaCO2 and higher PaO2 and OI than the azithromycin group (P<0.05). There was no significant difference in the incidence of adverse reactions between the two groups (P>0.05). Compared with treatment with azithromycin alone, intervention with TCM + azithromycin can significantly improve the respiratory function of patients with MP, reduce the degree of inflammatory response, and enhance the overall treatment effect without increasing the incidence of adverse reactions. This study indicates that intervention with traditional Chinese medicine and azithromycin can significantly improve the respiratory function of MP patients, reduce the degree of inflammatory response, improve overall treatment efficacy, and is safe.

Peripheral oxygen saturation levels as a guide to avoid hyperoxia: an observational study

BackgroundAs iatrogenic hyperoxia has been related to adverse outcomes in critically ill patients, guidelines advise to titrate oxygen to physiological levels. In the prehospital setting where partial arterial oxygen (PaO2) values are often not readily available, titration of oxygen is based on peripheral oxygen saturations (SpO2). In this study we aimed to investigate the efficacy of SpO2 guided oxygen titration in the prevention of hyperoxia.MethodsIn a retrospective observational cohort study of patients included in the Acutelines data- and biobank of the University Medical Center Groningen between September 2020 and March 2023, we collected blood gas samples and triage data of sequentially included patients who received oxygen at the moment they were presented in the emergency department (ED). PaO2 values were compared to (concurrently measured) SpO2 values, and to patient- and treatment characteristics and P/F ratios were calculated in order to investigate the efficacy of SpO2 based oxygen titration for various subgroups.ResultsBlood gas samples were obtained for 1042 patients, of which 178 (17.1%) had hyperoxia (PaO2 levels > 13.5 kPa). SpO2 readings were available for 170 of these, 68 of which (40%) had SpO2 values above the recommended target range (94–98%; 88–92% for patients with COPD) whereas 102 patients (60%) had SpO2 values within- or even below the recommended target range. Many of these patients (44.1%) received oxygen through a low-flow device (nasal canula), and these patients almost invariably (84.4%) were not compromised in their ventilation (P/F ratio’s > 300).ConclusionWhen oxygen is titrated based on SpO2 levels, this results in hyperoxemia in a significant proportion of the patients. Health care providers should especially be reluctant to administer (low flow) oxygen as a standard of care to patients who do not have clear respiratory compromise, as these patients are at a high risk of developing (occult) hyperoxia.

Hypoxia-Induced Reactive Oxygen Species: Their Role in Cancer Resistance and Emerging Therapies to Overcome It.

Normal tissues typically maintain partial oxygen pressure within a range of 3-10% oxygen, ensuring homeostasis through a well-regulated oxygen supply and responsive vascular network. However, in solid tumors, rapid growth often outpaces angiogenesis, creating a hypoxic microenvironment that fosters tumor progression, altered metabolism and resistance to therapy. Hypoxic tumor regions experience uneven oxygen distribution with severe hypoxia in the core due to poor vascularization and high metabolic oxygen consumption. Cancer cells adapt to these conditions through metabolic shifts, predominantly relying on glycolysis, and by upregulating antioxidant defenses to mitigate reactive oxygen species (ROS)-induced oxidative damage. Hypoxia-induced ROS, resulting from mitochondrial dysfunction and enzyme activation, exacerbates genomic instability, tumor aggressiveness, and therapy resistance. Overcoming hypoxia-induced ROS cancer resistance requires a multifaceted approach that targets various aspects of tumor biology. Emerging therapeutic strategies target hypoxia-induced resistance, focusing on hypoxia-inducible factors, ROS levels, and tumor microenvironment subpopulations. Combining innovative therapies with existing treatments holds promise for improving cancer outcomes and overcoming resistance mechanisms.

A Fuel Cell Power Supply System Equipped with Artificial Gill Membranes for Underwater Applications.

This work proposes a fuel cell power supply system for underwater applications (e.g., autonomous underwater vehicles), where artificial gills, based on a polymer membrane,harvest the required oxygen from the ambient water. In this system, a circulating air-flow continuously supplies a proton exchange membrane fuel cell with oxygen, which is replenished using a polymer membrane. The membrane serves as the interface between the circulating air-flow and the ambient water, preventing water flux while allowing an oxygen flux across the membrane, driven by a partial oxygen pressure gradient. To demonstrate the feasibility of this concept, a prototype system was built based on guidelines derived from a mathematical model that was developed to describe the oxygen transfer process. A computational fluid dynamics model is developed and validated against the measurements from the prototype, resulting in a digital twin. The analysis indicates that the proposed power supply system has the potential to be superior to any battery-based solution currently available.

Comparison of post-induction arterial partial oxygen pressure versus respiratory system compliance for predicting postanesthetic hypoxemia in 168 mechanically ventilated dogs

Comparison of post-induction arterial partial oxygen pressure versus respiratory system compliance for predicting postanesthetic hypoxemia in 168 mechanically ventilated dogs

Risk Factors for INtubation-SURfactant-Extubation Failure in Infants With Neonatal Respiratory Distress Syndrome

Risk Factors for INtubation-SURfactant-Extubation Failure in Infants With Neonatal Respiratory Distress Syndrome

Effect of cardiopulmonary bypass on late-onset hyperlactatemia after pediatric cardiac surgery

Background: This study aimed to investigate the effect of operative and postoperative parameters on late-onset hyperlactatemia (LOHL) after cardiac surgery in the pediatric patient population. Methods: One hundred fifty-nine ventricular septal defect patients (77 males, 82 females; mean age: 8.0±8.6 years; range, 1 to 48 years) were retrospectively examined between August 2020 and February 2023. Patients with the highest lactate value measured between 6 to 12 h postoperatively &lt;3 mmol/L were defined as Group 1, and those with lactate values ≥3 mmol/L (LOHL) were included in Group 2. Results: Cardiopulmonary bypass (CPB) time, aortic cross-clamp time, and CPB flow did not differ between groups (p=0.916, p=0.729, and p=0.699, respectively). The difference between partial oxygen pressure (PaO2) in the first blood gas obtained after CPB was statistically significant (p=0.017). The lactate level measured in the first arterial blood gas obtained after CPB was 1.74±0.61 mmol/L in Group 1 and 3.01±1.63 mmol/L in Group 2 (p&lt;0.001). The PaO2 in the arterial blood gas measured at 6 h postoperatively was 129.22±61.20 mmHg in Group 1 and 156.07±64.49 mmHg in Group 2 (p=0.046). Conclusion: The development of hyperlactatemia due to ischemia in the early post-CPB period may affect the development of LOHL. Microcirculatory changes at the tissue level may play a role in the etiology of LOHL.

Detection of serum FOXM1 and IGF2 in patients with ARDS and their correlation with disease and prognosis.

To investigate the relationship between the expression levels of serum forkhead box protein M1(FOXM1) and insulin-like growth factor 2 (IGF2) mRNA in patients with acute respiratory distress syndrome (ARDS) condition and prognosis. Ninety patients with ARDS admitted to our hospital were regarded as the ARDS group, according to the prognosis, they were grouped into death group (n = 64) and survival group (n = 126); the control group consisted of 190 healthy individuals. Compared with the control group, the level of serum FOXM1 mRNA in ARDS group was obviously lower, and the level of IGF2 mRNA was higher. The serum IGF2 mRNA, serum creatinine, inhaled oxygen concentration (FiO2), and mechanical ventilation time in the death group were higher than those in the control group, and the arterial oxygen partial pressure (PaO2), FOXM1 mRNA, and oxygenation index (PaO2/FiO2) were lower than those in control group. Logistic regression analysis indicated that FOXM1, IGF2, and PaO2/FiO2 were significant factors influencing the prognosis and mortality in ARDS patients. Correlation analysis showed that there was a negative correlation between serum FOXM1 and IGF2 mRNA levels in patients with ARDS. Serum FOXM1 and IGF2 mRNA in patients with ARDS are correlated with the severity and prognosis of ARDS.

Acid-base composition of mice blood during the progression of toxic pulmonary edema

BACKGROUND: Modeling toxic pulmonary edema for the purpose of studying the effectiveness of drugs is associated with difficulties in model validation and objectification of drug effectiveness criteria. To confirm the significance of changes in pulmonary coefficients and visual changes in lung tissue, acid-base balance and blood gas analysis are often used to objectify emerging gas exchange disorders. AIM: To investigate the acid-base composition and blood gases in mice during the progression of toxic pulmonary edema caused by inhalational phosgene exposure. MATERIAL AND METHODS: Toxic pulmonary edema was induced by exposing mice to phosgene at a dose corresponding to LCt50 in an inhalation chamber. Blood samples were analyzed for acid-base balance and gas parameters, including partial oxygen pressure (pO2), partial carbon dioxide pressure (pCO2), total hemoglobin (tHb), oxyhemoglobin (O2Hb), carboxyhemoglobin (COHb), methemoglobin (MetHb), reduced hemoglobin (RHb), oxygen saturation (sO2), oxygen concentration (O2ct), oxygen capacity (O2cap), partial oxygen pressure at 50 % saturation (P50), total carbon dioxide (tCO2), true and standard bicarbonate (HCO3–, SBC), actual and standard base excess (BEb, BEecf), anion gap, lactate, and concentrations of sodium, potassium, chloride, and ionized calcium. Measurements were performed using a gas analyzer at 30 minutes, 3 hours, and 24 hours after exposure initiation. RESULTS: Significant shifts in blood gas composition and acid-base balance were observed 3 hours after pulmonary edema initiation. These included decreased acid-base balance, reduced oxyhemoglobin levels, lowered oxygen saturation, and elevated partial carbon dioxide pressure, indicating respiratory insufficiency and compensated respiratory acidosis. Major changes in acid-base parameters were observed after 24 hours, with normalization of pH accompanied by increases in true and standard bicarbonate levels, as well as total carbon dioxide content. Changes in actual and standard base excess were observed, reflecting a reduction in base deficit. Electrolyte levels remained unchanged in all experimental groups throughout all observation periods. CONCLUSIONS: The study elucidated the progression of respiratory hypoxia during toxic pulmonary edema and confirmed that respiratory hypoxia serves as a key pathogenic link, leading to significant disruptions in energy metabolism during the progression of pulmonary edema.

Cortex kidney tissue partial oxygen pressure depends on percentage of active oxygenation during oxygenated hypothermic machine perfusion.

Preclinical and clinical studies have demonstrated the advantages of oxygenated hypothermic machine perfusion (HMPO2) during kidney preservation. However, the optimal oxygenation levels during HMPO2 remain undetermined. The aim of this study was to compare different levels of oxygenation (0%, 21%, 50%, and 100%) during 22 h of active oxygenated HMP (HMPO2) using oxygen preloading by bubbling oxygenation in the preservation solution and continuous surface oxygenation during MP in a porcine DCD model. After 60 min of warm ischemia time, both kidneys of an 80 kg pig were procured and randomized to one of the following groups: (1) 22-h static cold storage (n = 6), (2) 22-h HMP without active oxygenation (n = 6), (3) 22-h HMPO2 21% O2 (n = 6), (4) 22-h HMPO2 50% O2 (n = 6), and (5) 22-h HMPO2 100% O2 (n = 6). The primary outcome measure was to compare the different oxygen levels among the different groups assessed by cortex kidney tissue oxygen partial pressures (tpO2). Continuous HMPO2 resulted in a significant modification of cortex kidney tpO2. In addition, tpO2 was dependent on the percentage of oxygenation. One hundred percent oxygen resulted in a significantly higher tpO2 compared to all other study groups. In line with that, ATP resynthesis was significantly higher in the HMPO2 100% group. This study demonstrates that continuous HMPO2 results in a significant modification of tpO2 compared with SCS, and the degree of tpO2 is positively correlated with the percentage of active oxygenation during HMP. Metabolic profile analyses (ATP resynthesis) suggest that the aerobic mechanism is better supported with higher oxygen levels (50% and 100% oxygenation).

In Vivo Mouse Abdominal Oxygen Imaging And Assessment of Subcutaneously Implanted Beta Cell Replacement Devices.

In Vivo Mouse Abdominal Oxygen Imaging And Assessment of Subcutaneously Implanted Beta Cell Replacement Devices.

A Multiscale Mathematical Model for Fetal Gas Transport and Regulatory Systems During Second Half of Pregnancy.

Fetal asphyxia, a condition resulting from the combined effects of hypoxia and hypercapnia, leads to approximately 900,000 annual deaths worldwide. One cause is umbilical cord compression during labor-induced uterine contractions, disrupting the transport of metabolites to and from the placenta, and resulting in asphyxia. Current fetal well-being assessment relies on monitoring fetal heart rate and uterine contractions as indicators of oxygen delivery to the brain. To enhance our understanding of this complex relationship, this study aims to develop a modular mathematical model including fetal blood gas dynamics, the autonomic nervous system, and cerebral blood flow regulation. The novelty of this study lies in the capability of the model to simulate fetal growth. These submodels are part of a larger multiscale mathematical model describing fetal circulation in the second half of pregnancy. The blood gas model realistically replicates partial oxygen and carbon dioxide pressures in umbilical arteries and veins during healthy fetal development reported in the literature. An in silico experiment is conducted to simulate umbilical cord occlusion and is compared with lamb experiments to verify the realism of the regulation models during fetal growth. Our findings suggest that premature infants are more susceptible to umbilical cord occlusion, exhibiting elevated cerebral perfusion pressure and flow. This modular mathematical model may serve as a valuable tool for testing hypotheses related to the fetal regulatory system.

Investigation of Topography and Electrical Properties of K0.3MoO3 Thin Films

Abstract In this article we investigate topography and electrical properties of potassium blue bronze thin films by the means of atomic force microscopy. Thin films were prepared by pulsed laser depositions on two types of substrates (Al2O3 and SrTiO3) at different substrate temperatures and partial oxygen pressures. On the basis of topography measurements, granular nature of the films was revealed. Surface roughness, as well as the size and the orientation of grains was determined. Films deposited on SrTiO3 substrates are quite homogeneous and the grains display ordering in preferential directions. Films on Al2O3 contain randomly oriented grains. Roughness of the films increases with the increase of the deposition temperature. Electrical measurements provided qualitative information regarding the electrical properties of the films.

Quantitative Conversion of Sulfate Oxygen for High-Precision Triple Oxygen Isotope Analysis.

Triple oxygen isotope composition (Δ'17O) of sulfate carries information on the sulfur cycle as well as signatures of atmospheric O2, O3, and surface water of the geological past. However, existing analytical techniques can only achieve a partial oxygen yield during the conversion from sulfate to the analyte O2, which results in isotope fractionation and impedes the Δ'17O comparison with other oxygen-bearing compounds (e.g., H2O) on the VSMOW-SLAP scale. Here, we present an analytical method involving high-temperature graphite reduction, CO discharge, and Pt-catalyzed CO2-O2 isotope exchange, the R-D-E method, that achieves ∼100% conversion of sulfate oxygen to CO2. Compared with the widely used CO2-laser-fluorination technique, our R-D-E method has a better Δ'17O precision (9 per meg) and requires a smaller sample amount, as low as 4 μmol of sulfate (equivalent to 1 mg BaSO4), with both Δ'17O and δ18O being determined simultaneously. Using this method, we report the triple oxygen isotope compositions of three international reference materials (NBS-127, IAEA-SO-5, and IAEA-SO-6) and three in-house references on the VSMOW-SLAP scale. We found that the sulfate Δ'17O values measured on the partially yielded O2 from the fluorination technique are 10-200 per meg higher than those obtained by our R-D-E method, depending on the oxidant used (e.g., F2 or BrF5). Incomplete conversion of sulfate oxygen during the high-temperature graphite reduction would result in lower δ18O and higher Δ'17O values. This work highlights the needs for recalibration and reinterpretation of the published sulfate Δ'17O data when sulfate Δ'17O values of interest are small.

Oxygen Concentration and Reaction Rate Profiles Analysis of Polymer Electrolyte Fuel Cell

Introduction A one-dimensional (1D) model of polymer electrolyte fuel cells (PEFCs) is especially suitable for performance diagnostics, design optimization, and material evaluation, due to its high computational efficiency. Uniform distributions of reactants are commonly assumed in 1D models, i.e., a single representative reactant concentration inside the gas channel is required. However, this concentration is strongly dependent on the flow field. Although plenty of 1D models with sufficient accuracy as 3D models have been reported, the effects of the flow field have not been sufficiently discussed in the literature. In this work, efforts have been put into developing a generalized theory suitable for various flow fields to quantitatively analyze the in-plane reaction rate profile, so that the flow-field-sensitive representative reactant concentration can be employed to further fill the gaps in the 1D models. Analytical model A series of a plug flow reactor (PFR) and a continuous stirred tank reactor (CSTR) was proposed to explain the unideal flow and the macromixing behaviors inside a gas channel coupled with a gas diffusion layer (GDL), as shown in Fig. 1(a).[1] The fraction of PFR’s space time to total space time was defined as the characterization factor γ, which should be the function of flow field shape and flow rate. Furthermore, under-rib oxygen concentration and current density profiles were taken into account by introducing the dimensionless moduli.[2] Especially, the under-rib convection can be evaluated by Péclet modulus Pe, by increasing which will improve the under-rib mass transfer and the effectiveness factor f. The in-plane profile of the ohmic resistance of the membrane was assumed uniform. The oxygen reduction reaction (ORR) was regarded as a surface reaction occurring on the interface of cathode catalyst layer (CCL) and GDL. The ORR rate was assumed to be proportional to oxygen partial pressure and independent of relative humidity (RH). Results and Discussion The characterization factors γ of different flow fields were determined according to the residence time distribution simulated by the computational fluid dynamics (CFD) model. The ORR rate constant at each electrical potential was obtained from the measured polarization curve of a parallel gas channel (PN0) with 0.35 mm channel depth, by employing the analytical model mentioned above. Fig. 1(c) shows the polarization curves of parallel channels with staggered 1-mm-long partially narrowed structures (PSN1) and PN0 with different channel depths. Compared to the PN0, the under-rib convection improves the oxygen mass transport and the cell performance, where f increases 17 % at 0.35 V in the case of the PSN1. On the other hand, increasing the channel depth restrains the oxygen diffusion and f decreases by 18 % at 0.35 V. The analytical model results show good agreement with experiment data, which indicates that the effects of the flow field can be summarized by the parameters γ and f.The analytical model provides the in-plane oxygen mole fraction and current density profiles. Fig. 2 shows the oxygen partial pressure distribution in a single gas channel calculated by the CFD model and analytical model. The mean oxygen partial pressure on the under-channel CCL-GDL interface calculated by the analytical model approximately equals the CFD result. By employing the ohmic resistance estimated according to the inlet conditions, although the current density is underestimated where RH is high, the integral mean of the in-plane current density offered by the analytical model has less than 5 % error compared to the CFD results, as shown in Fig. 3.The analytical model also gives an effective way to estimate the integral mean in-plane oxygen partial pressure. Fig. 4 demonstrates the relationships among integral mean, inlet, and outlet oxygen partial pressures. When the reaction rate constant and effectiveness factor are fixed, Fig. 4 also reveals the relationships between total and local current densities. If the parameters γ and f are determined, the integral mean of the oxygen partial pressure can be obtained when the outlet oxygen partial pressure or oxygen conversion is known. Conclusions The analytical model quantitatively demonstrates the effects of the flow field shape and provides a quick and effective way to estimate the reaction rate profile, based on the fixed in-plane ohmic resistance assumption. This model was verified by experiment and CFD model in case of the oxygen conversion less than 0.33 and can be applied to ORR kinetics determination and rapid performance prediction. Reference [1] Y. Ma et al., J. Electrochem. Soc., 170, 084506 (2023).[2] Y. Ma et al., ECS Meet. Abstr., MA2023-02, 1867 (2023). Figure 1

Factors Affecting Long-Term Cycle Stability of Cobalt-Free Li2MnO3-Based Materials

A layered-type solid solution material between Li2MnO3 and LiNi0.5Mn0.5O2, Li1.2Ni0.2Mn0.6O2, delivers a large reversible capacity over 220 mA h g–1, which exceeds the theoretical capacity calculated based on cationic redox of transition metal ions, through reversible anionic redox of oxide ions. However, a practical problem of this material is found in the poor electrode reversibility associated with partial oxygen loss during charging process. In this study, Li1.2Al0.04Ni0.18Mn0.58O2, where Ni and Mn ions are partially substituted with Al ions, is synthesized via a solid-state reaction under different synthesis conditions, and its electrochemical performance as a positive electrode material is examined. Li1.2Al0.04Ni0.18Mn0.58O2 samples are synthesized at various sintering temperatures ranging from 850 to 1100 oC, and single-phase samples are obtained except for 850 oC. Al3+ substitution effectively suppresses the capacity fading and voltage decay of Li1.2Ni0.2Mn0.6O2. In addition, Li1.2Al0.04Ni0.18Mn0.58O2 delivers a large reversible capacity of over 200 mA h g–1 through optimizing the specific surface area. Furthermore, the use of highly concentrated electrolytes with high oxidative stability and low solubility of Mn ions effectively improves electrode reversibility of Li1.2Al0.04Ni0.18Mn0.58O2. From these results, factors affecting the electrode properties of cobalt-free Li-rich layered oxides will be discussed in detail.

Study of Physiological Adaptations in Vertical Kilometer Runners: Focus on Cardiorespiratory and Local Muscle Demands.

Background: Research into key performance factors in trail running, particularly in vertical kilometer (VK) races, is crucial for effective training and periodization. However, recent studies on metabolic and cardiorespiratory responses during VK races, especially using field tests, are limited. Objectives: Therefore, the aim of this study is to evaluate the metabolic and cardiorespiratory responses during a VK field test, identifying differences based on sex and performance level, as well as key performance factors and their deterioration due to fatigue. Fifteen trained trail runners (ten males and five females, 19 to 38 years old) perform a VK race. Methods: The global physiological response is evaluated using the portable gas analyzer Cosmed K5 and the local response using near-infrared spectroscopy technology. Results: In gender comparisons, the ANCOVA test shows significant differences (p < 0.05) in the ventilation, tidal volume, expiratory time-to-inspiratory time ratio, inspiratory flow rate, end-tidal CO2 partial pressure, heart rate, oxygen pulse, and total hemoglobin. Additionally, the performance comparison reveals significant differences in the variables' velocity, oxygen consumption, carbon dioxide production, ventilation, dead space-to-tidal volume ratio, total time of the breathing cycle, expiratory time-to-inspiratory time ratio, inspiratory duty cycle, expiratory fractions of CO2, quadriceps saturation index, and VE/VCO2 ratio. Finally, the correlation analysis shows oxygen consumption (r = -0.80 mean; r = -0.72 peak), carbon dioxide production (r = -0.91 mean; r = -0.75 peak), expiratory time-to-inspiratory time ratio (r = 0.68 peak), ventilation (r = -0.58 mean), and quadriceps saturation index (r = 0.54 mean; r = -0.76 coefficient of variation) as the key performance factors in the VK race. Conclusions: Overall, the physiological analysis indicates the importance of local muscular adaptations and respiratory system capacity in this type of short-duration race.