Oxygen Transport Research Articles

Parameter quantification for oxygen transport in the human brain

Background and objective:Oxygen is carried to the brain by blood flow through generations of vessels across a wide range of length scales. This multi-scale nature of blood flow and oxygen transport poses challenges on investigating the mechanisms underlying both healthy and pathological states through imaging techniques alone. Recently, multi-scale models describing whole brain perfusion and oxygen transport have been developed. Such models rely on effective parameters that represent the microscopic properties. While parameters of the perfusion models have been characterised, those for oxygen transport are still lacking. In this study, we set to quantify the parameters associated with oxygen transport and their uncertainties. Methods:Effective parameter values of a continuum-based porous multi-scale, multi-compartment oxygen transport model are systematically estimated. In particular, geometric parameters that capture the microvascular topologies are obtained through statistically accurate capillary networks. Maximum consumption rates of oxygen are optimised to uniquely define the oxygen distribution over depth. Simulations are then carried out within a one-dimensional tissue column and a three-dimensional patient-specific brain mesh using the finite element method. Results:Effective values of the geometric parameters, vessel volume fraction and surface area to volume ratio, are found to be 1.42% and 627 [mm2/mm3], respectively. These values compare well with those acquired from human and monkey vascular samples. Simulation results of the one-dimensional tissue column show qualitative agreement with experimental measurements of tissue oxygen partial pressure in rats. Differences between the oxygenation level in the tissue column and the brain mesh are observed, which highlights the importance of anatomical accuracy. Finally, one-at-a-time sensitivity analysis reveals that the oxygen model is not sensitive to most of its parameters; however, perturbations in oxygen solubilities and plasma to whole blood oxygen concentration ratio have a considerable impact on the tissue oxygenation. Conclusions:The findings of this study demonstrate the validity of using a porous continuum approach to model organ-scale oxygen transport and draw attention to the significance of anatomy and parameters associated with inter-compartment diffusion.

Analyzing Uttarakhand's COVID-19 Outbreak: Demographic Insights and Strategies for Future Pandemic Prevention

Background:: The Indian state of Uttarakhand, also known as "Dev Bhoomi" or the Abode of Gods, is snuggled in the lap of the Himalayas. It is endowed with an abundant natural hilly environment and occupies more people in total than Israel, Switzerland, Hong Kong, etc. In this report, we look closely at the impact of COVID-19 on both high land/ hilly and low land/ plain bhabar zones across the state. Methods:: The data was retrieved from the Uttarakhand Government Covid-19 health bulletin for 12 months using the Python command line. The data analysis covers percentage positivity/COVID-19 positivity rate, recovery, deceased and doubling rate, along with a detailed statistical analysis. Results:: In the first wave, low-land- inhabitants residing in 4 districts, Dehradun, Haridwar, U. S. Nagar and Nainital, were found more vulnerable, with a peak positive case during the 21st – 26th week. On the other hand, the districts with exclusive hilly terrains, including Chamoli, Pauri Garhwal, and Rudraprayag, were found to be the least susceptible and reported a high number of positive cases between the 30th and 31st week. The highest recovery rate was found to be in the hilly district of Rudraprayag. The multiple regression with confirmed cases was explained in relation to deceased, recovered, other, and tested variables (R2 adj= 0.99). The analysis also revealed a very high doubling rate from the last week of May to the first week of Jun 2020. Conclusion:: The reduced number of COVID-19 cases in high-altitude hilly districts may be associated with factors such as enhanced ventilation, improved arterial oxygen transport, and increased tissue oxygenation. The findings from this study offer insights that can contribute to future pandemic prevention efforts. Summarising the current study, we have suggested 5-point solutions for preventing the next pandemic. It's important to note that while this study suggests a potential link between these factors and lower COVID-19 cases, further research is needed to establish a conclusive connection.

New insights into the mechanisms of red blood cell enucleation: From basics to clinical applications

AbstractBackgroundRed blood cell (RBC) enucleation is a crucial step in the process of erythropoiesis. By removing the nucleus, RBCs gain greater flexibility, enabling them to traverse narrow capillaries with ease, thereby enhancing the efficiency of oxygen and carbon dioxide transport. This transformation underscores the intricate balance between cellular structure and function essential for maintaining homeostasis.TopicThis review delves into the multifaceted enucleation process, outlining its complex steps that encompass protein sorting, vesicle trafficking, cytoskeletal remodeling, and apoptosis regulation, while also exploring the potential of enhancing the enucleation rate of RBCs in vitro. We emphasize the intricate regulation of this process, which is orchestrated by multiple factors. This includes transcription factors that meticulously guide protein synthesis and sorting through the modulation of gene expression, as well as non‐coding RNAs that play a pivotal role in post‐transcriptional regulation during various stages of RBC enucleation. Additionally, macrophages participate in the enucleation process by engulfing and clearing the extruded nuclei, further ensuring the proper development of RBCs. Although many studies have deeply explored the molecular mechanisms of enucleation, the roles of apoptosis and anti‐apoptotic processes in RBC enucleation remain incompletely understood.ImplicationIn this review, we aim to comprehensively summarize the RBC enucleation process and explore the progress made in ex vivo RBC generation. In the future, a deeper understanding of the enucleation process could provide significant benefits to patients suffering from anemia and other related conditions.

Deep-GB: A novel deep learning model for globular protein prediction using CNN-BiLSTM architecture and enhanced PSSM with trisection strategy.

Globular proteins (GPs) play vital roles in a wide range of biological processes, encompassing enzymatic catalysis and immune responses. Enzymes, among these globular proteins, facilitate biochemical reactions, while others, such as haemoglobin, contribute to essential physiological functions such as oxygen transport. Given the importance of these considerations, accurately identifying Globular proteins is essential. To address the need for precise GP identification, this research introduces an innovative approach that employs a hybrid-based deep learning model called Deep-GP. We generated two datasets based on primary sequences and developed a novel feature descriptor called, Consensus Sequence-based Trisection-Position Specific Scoring Matrix (CST-PSSM). The model training phase involved the application of deep learning techniques, including the bidirectional long short-term memory network (BiLSTM), gated recurrent unit (GRU), and convolutional neural network (CNN). The BiLSTM and CNN were hybridised for ensemble learning. The CST-PSSM-based ensemble model achieved the most accurate predictive outcomes, outperforming other competitive predictors across both training and testing datasets. This demonstrates the potential of harnessing deep learning for precise GB prediction as a robust tool to expedite research, streamline drug discovery, and unveil novel therapeutic targets.

Genome-wide local ancestry and the functional consequences of admixture in African and European cattle populations.

Bos taurus (taurine) and Bos indicus (indicine) cattle diverged at least 150,000 years ago and, since that time, substantial genomic differences have evolved between the two lineages. During the last two millennia, genetic exchange in Africa has resulted in a complex tapestry of taurine-indicine ancestry, with most cattle populations exhibiting varying levels of admixture. Similarly, there are several Southern European cattle populations that also show evidence for historical gene flow from indicine cattle, the highest levels of which are found in the Central Italian White breeds. Here we use two different software tools (MOSAIC and ELAI) for local ancestry inference (LAI) with genome-wide high- and low-density SNP array data sets in hybrid African and residually admixed Southern European cattle populations and obtained broadly similar results despite critical differences in the two LAI methodologies used. Our analyses identified genomic regions with elevated levels of retained or introgressed ancestry from the African taurine, European taurine, and Asian indicine lineages. Functional enrichment of genes underlying these ancestry peaks highlighted biological processes relating to immunobiology and olfaction, some of which may relate to differing susceptibilities to infectious diseases, including bovine tuberculosis, East Coast fever, and tropical theileriosis. Notably, for retained African taurine ancestry in admixed trypanotolerant cattle we observed enrichment of genes associated with haemoglobin and oxygen transport. This may reflect positive selection of genomic variants that enhance control of severe anaemia, a debilitating feature of trypanosomiasis disease, which severely constrains cattle agriculture across much of sub-Saharan Africa.

Cu-Based Praseodymium-Modified γ-Al2O3 Oxygen Carrier for Chemical Looping Combustion Process Optimization

Chemical looping combustion (CLC) emerges as a cost-effective CO2 capture technology, demonstrating high competitiveness for both industrial and energy applications. This study explores the synthesis of a Cu-based, praseodymium (Pr)-modified gamma-alumina-supported (20CuPA) oxygen carrier (OC) through the wet impregnation method and investigates its performance in CLC. The characteristics of the synthesized OC were investigated using field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, temperature-programmed reduction analysis, and X-ray diffraction analysis. The CLC of methane gas was performed in a thermogravimetric analyzer (TA-Q50). The oxygen transport capacity (OTC) of the 20CuPA-based OC was investigated for 10 redox cycles. The impact of temperature and time as process variables in determining the OTC of OCs was studied. The TGA results indicated that the most important factor influencing the optimization of the OTC of OCs was time. In comparison to time, temperature had less of an impact on the OTC of 20CuPA-OC. The maximum OTC of 20CuPA-OC, which was 0.0546 mg of O2/mg of OC, was reached using optimized process variables, including a temperature of 800 °C and a time of 3 min.

Modular Assembly of Photoactive Lipid Nanoparticles on Red Blood Cells toward Enhanced Phototherapy Efficacy.

Photodynamic therapy has been developed as a promising treatment for malignant tumors, which inspires research into photosensitizers. However, the therapeutic efficacy of individual photosensitizers is often hampered by the physiological environment. The assembly of biological materials with synthetic molecules offers a strategy to enhance functionality while improving tolerance to varying physiological conditions. Herein, we present a biohybrid system for enhanced phototherapy efficacy through a simple two-step assembly process. Photoactive lipid nanoparticles were assembled based on synthesized conjugated molecules and lipophilic prodrugs, which were then modularly assembled with red blood cells (RBCs). Driven by hydrophobic and electrostatic interactions, hydrophobic conjugated molecules were efficiently incorporated into the RBCs, while lipophilic prodrugs were simultaneously inserted into the cell membranes. The engineered RBCs harnessed the natural oxygen transport capability, enabling the internal conjugated molecules to effectively produce reactive oxygen species (ROSs) even under oxygen-poor conditions. Meanwhile, the use of ROS-cleavable linkers in prodrugs enhanced drug release for chemotherapy, which is a perfect complement to photodynamic therapy. In vitro and in vivo experiments proved the improved phototherapy efficacy of the biohybrid system. Furthermore, the changes in aggregation directed Förster resonance energy transfer between conjugated molecules and fluorescent drugs provided a mechanism to track drug release from engineered RBCs. Therefore, the modular assembly of biohybrid systems can offer multiple functionalities required for phototherapy, on-demand drug release, and imaging.

Research Progress of Spectral Imaging Techniques in Plant Phenotype Studies.

Spectral imaging technique has been widely applied in plant phenotype analysis to improve plant trait selection and genetic advantages. The latest developments and applications of various optical imaging techniques in plant phenotypes were reviewed, and their advantages and applicability were compared. X-ray computed tomography (X-ray CT) and light detection and ranging (LiDAR) are more suitable for the three-dimensional reconstruction of plant surfaces, tissues, and organs. Chlorophyll fluorescence imaging (ChlF) and thermal imaging (TI) can be used to measure the physiological phenotype characteristics of plants. Specific symptoms caused by nutrient deficiency can be detected by hyperspectral and multispectral imaging, LiDAR, and ChlF. Future plant phenotype research based on spectral imaging can be more closely integrated with plant physiological processes. It can more effectively support the research in related disciplines, such as metabolomics and genomics, and focus on micro-scale activities, such as oxygen transport and intercellular chlorophyll transmission.

Computer model coupling hemodynamics and oxygen transport in the coronary capillary network: Pulsatile vs. non-pulsatile analysis

Background and Objective:Oxygen transport in the heart is crucial, and its impairment can lead to pathological conditions such as hypoxia, ischemia, and heart failure. However, investigating oxygen transport in the heart using in vivo measurements is difficult due to the small size of the coronary capillaries and their deep embedding within the heart wall. Methods:In this study, we developed a novel computational modeling framework that integrates a 0-D hemodynamic model with a 1-D mass transport model to simulate oxygen transport in/across the coronary capillary network. Results:The model predictions agree with analytical solutions and experimental measurements. The framework is used to simulate the effects of pulsatile vs. non-pulsatile behavior of the capillary hemodynamics on oxygen-related metrics such as the myocardial oxygen consumption (MVO2) and oxygen extraction ratio (OER). Compared to simulations that consider (physiological) pulsatile behaviors of the capillary hemodynamics, the OER is underestimated by less than 9% and the MVO2 is overestimated by less than 5% when the pulsatile behaviors are ignored in the simulations. Statistical analyses show that model predictions of oxygen-related quantities and spatial distribution of oxygen without consideration of the pulsatile behaviors do not significantly differ from those that considered such behaviors (p-values >0.05). Conclusions:This finding provides the basis for reducing the model complexity by ignoring the pulsatility of coronary capillary hemodynamics in the computational framework without a substantial loss of accuracy when predicting oxygen-related metrics.

Genome sequencing and transcriptome analysis provide an insight into the hypoxia resistance of Channa asiatica

Channa asiatica is an economically valuable fish species and excellent model for studying hypoxic tolerance. However, the underlying genetic and molecular mechanisms are poorly understood. In this study, we assembled a high-quality C. asiatica genome (23 chromosomes, totaling 722 Mb) using a combination of Illumina short-read, PacBio long-read, and Hi-C sequencing. Repetitive elements accounted for 28.39%of the C. asiatica genome, and 23,949 protein-coding genes were predicted, with 96.63 % of these functionally annotated. Moreover, a comparative genomic analysis of 12 fish genomes showed that gene families associated with oxygen binding and transport were expanded in C. asiatica. In addition, transcriptome analysis revealed that multiple oxidative stress pathways were activated when C. asiatica was exposed to air. In conclusion, this study provided high-quality genome assembly and transcriptome data, both serving as critical resources for researching the genetic basis of hypoxic tolerance in C. asiatica.

Folic Acid Before and During Pregnancy

Folate is a key nutrient required to maintain optimal health, especially when planning a family or during pregnancy. The functionality of folate centres on the production of healthy red blood cells, important for the transportation of oxygen around the body. It supports development of the foetal nervous system specifically neural tube growth, with evidence showing that taking folic acid supplements before and during pregnancy reduces the chance of the baby developing spina bifida and other conditions affecting the spine and neural tube.1 Folate is essential for DNA replication, and may protect against miscarriage, premature birth and low birth weight, with beneficial effects in the prevention of structural anomalies, congenital heart disease and oral clefts.2

Breath inspired multifunctional low-cost inorganic colloidal electrolyte for stable zinc metal anode

The practical application of aqueous zinc-ion batteries (AZIBs) is primarily constrained by issues such as corrosion, zinc dendrite formation, and the hydrogen evolution reaction occurring at the zinc metal anode. To overcome these challenges, strategies for optimizing the electrolyte are crucial for enhancing the stability of the zinc anode. Inspired by the role of hemoglobin in blood cells, which facilitates oxygen transport during human respiration, an innovative inorganic colloidal electrolyte has been developed: calcium silicate-ZnSO4 (denoted as CS-ZSO). This electrolyte operates in weak acidic environment and releases calcium ions, which participate in homotopic substitution with zinc ions, while the solvation environment of hydrated zinc ions in the electrolyte is regulated. The reduced energy barrier for the transfer of zinc ions and the energy barrier for the desolvation of hydrated ions imply faster ion transfer kinetics and accelerated desolvation processes, thus favoring the mass transfer process. Furthermore, the silicate colloidal particles act as lubricants, improving the transfer of zinc ions. Together, these factors contribute to the more uniform concentration of zinc ions at the electrode/electrolyte interface, effectively inhibiting zinc dendrite formation and reducing by-product accumulation. The Zn//CS-ZSO//Zn symmetric cell demonstrates stable operation for over 5000 h at 1 mA cm−2, representing 29-fold improvement compared to the Zn//ZSO//Zn symmetric cell, which lasts only 170 h. Additionally, the Zn//CS-ZSO//Cu asymmetric cell shows stable average Coulombic efficiency (CE) exceeding 99.6% over 2400 cycles, significantly surpassing the performance of the ZSO electrolyte. This modification strategy for electrolytes not only addresses key limitations associated with zinc anodes but also provides valuable insights into stabilizing anodes for the advancement of high-performance aqueous zinc-ion energy storage systems.

Recycling of hydrogen tolerant La0.6Ca0.4Co0.2Fe0.8O3–d oxygen transport membranes with integrated life cycle assessment for plasma-assisted CO2-conversion

In this study, a recycling approach was adapted for the hydrogen tolerant La0.6Ca0.4Co0.2Fe0.8O3–d (LCCF_6428) oxygen transport membranes that have great potential in plasma-assisted CO2 conversion techniques for producing industrial fuels such as methanol. The major focus was the incorporation of sustainability measures such as integrating life cycle assessment (LCA) into the materials development at an early stage to study and compare the environmental feasibility of the recycled membrane with the primary membrane. The aim was also to ensure reduced resource depletion of critical raw materials such as cobalt and lanthanum by means of recycling. It consisted of microwave-assisted dissolution of the membrane followed by ultrasonic spray synthesis. The recycled membrane exhibited at least 83 % of the oxygen permeability of the primary membrane and maintained hydrogen tolerance up to 600 °C for 25 h which is a remarkable result for LCCF_6428 in terms of potentially enhancing its life span. As per the LCA, recycling did result in lower resource depletion. However, the recycled LCCF had a higher overall environmental impact compared to the primary LCCF, mainly due to increased electricity consumption during recycling. These results accentuate the need for a transition towards more efficient processes accompanied by cleaner and renewable sources of energy and critically indicate integration of LCA into materials development to establish the sustainability profile of materials.

Patient-specific prostate tumour growth simulation: a first step towards the digital twin.

Prostate cancer (PCa) is a major world-wide health concern. Current diagnostic methods involve Prostate-Specific Antigen (PSA) blood tests, biopsies, and Magnetic Resonance Imaging (MRI) to assess cancer aggressiveness and guide treatment decisions. MRI aligns with in silico medicine, as patient-specific image biomarkers can be obtained, contributing towards the development of digital twins for clinical practice. This work presents a novel framework to create a personalized PCa model by integrating clinical MRI data, such as the prostate and tumour geometry, the initial distribution of cells and the vasculature, so a full representation of the whole prostate is obtained. On top of the personalized model construction, our approach simulates and predicts temporal tumour growth in the prostate through the Finite Element Method, coupling the dynamics of tumour growth and the transport of oxygen, and incorporating cellular processes such as proliferation, differentiation, and apoptosis. In addition, our approach includes the simulation of the PSA dynamics, which allows to evaluate tumour growth through the PSA patient's levels. To obtain the model parameters, a multi-objective optimization process is performed to adjust the best parameters for two patients simultaneously. This framework is validated by means of data from four patients with several MRI follow-ups. The diagnosis MRI allows the model creation and initialization, while subsequent MRI-based data provide additional information to validate computational predictions. The model predicts prostate and tumour volumes growth, along with serum PSA levels. This work represents a preliminary step towards the creation of digital twins for PCa patients, providing personalized insights into tumour growth.

A comparative study on the Lattice Boltzmann Method and the VoF-Continuum method for oxygen transport in the anodic porous transport layer of an electrolyzer

The optimization of Polymer Electrolyte Membrane (PEM) electrolyzers necessitates an intimate knowledge of the oxygen flows within the anodic porous transport layers (PTLs) to determine any possible reduction in performance. In this field, as experimental studies are cumbersome and expensive, numerical modeling has arisen as a viable alternative for studying the oxygen transport within the Anodic PTLs of a PEM electrolyzer. Amongst the various numerical modeling techniques, the Lattice Boltzmann Method (LBM) is gaining prominence for its effectiveness in analyzing fluid transport within porous media due to its mesoscopic nature and ease of implementation. This study utilizes the Shan-Chen LBM methodology to model the flow of oxygen within the Anodic PTL of a PEM electrolyzer and compares it against the Volume-of-Fluid-based Continuum Model. The results show that LBM can not only replicate the experimental studies accurately, but can also maintain its high accuracy at progressively shrinking length scales of PTLs, even at length scales where the VoF-based Continuum Model would run into accuracy issues. The high accuracy of the LBM model, combined with the simplicity of the LB algorithm makes LBM a powerful technique for simulating the microfluidic flows such as the flow of oxygen within the Anodic PTL of a PEM electrolyzer.

Performance constraints of high temperature polymer electrolyte membrane fuel cells by varying the Pt/C ratio of the catalyst

Electrodes prepared from catalysts with Pt weight percentages on the carbon support (Pt/C nanoparticles) ranging from 10 up to 60 wt% are used as cathodes of membrane electrode assemblies (MEAs) and tested in high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). For each Pt/C percentage in the catalyst, the cathode Pt-loading (which become proportional to the thickness of the electrode formed by the catalyst nanoparticles) is stepwise scanned from low to high loadings. Results show that when the Pt load increases, the MEA performance (measured by its power density at 0.6 V) rises initially (due to the increase in the number of active sites in the cathode) up to a maximum value limited by the mass transport of oxygen, associated to an optimum Pt-loading (different for each Pt/C ratio). Noteworthy, the peak performance is significantly different depending on the catalyst used (60 > 40 >> 20 > 10 wt% Pt/C), a fact that restricts the catalyst choice according to the performance required by the application. Furthermore, higher amounts of Pt in the cathode lead to a large catalyst waste as the FC performance even decreases as the cathode thickness increases.

Primary inflammatory disease in heart failure with preserved ejection fraction

Abstract Background Inflammation plays a fundamental role in the pathogenesis of heart failure (HF) with preserved ejection fraction (HFpEF). In most patients, inflammation develops secondary to cardiometabolic comorbidities, but in some, HFpEF develops in the setting of underlying systemic inflammatory diseases represented by rheumatoid arthritis. Purpose This study aimed to investigate the prevalence, pathophysiology, and outcome of patients with HFpEF and primary inflammatory diseases. Methods Consecutive patients undergoing hemodynamic exercise testing with concurrent expiratory gas analysis to evaluate dyspnea of unknown cause were identified. HFpEF was defined as left ventricular ejection fraction ≥50% and pulmonary capillary wedge pressure ≥15 mmHg (rest) or ≥25 mmHg (exercise). Patients with HFpEF were divided into groups with and without primary inflammatory diseases. Patients without inflammatory disease were divided into tertiles according to the value of C-reactive protein (CRP). Results Of 982 consecutively evaluated patients with HFpEF diagnosed (577 female, mean age 68 years), 79 (8%) had primary inflammatory disease. In multivariable logistic regression, female sex (OR 1.88; 95% CI 1.01-3.52), higher resting heart rate (OR 1.18; 95% CI 1.08-1.30), lower hemoglobin level (OR 0.84; 95% CI 0.70-0.99), absence of history of atrial fibrillation (OR 0.45; 95% CI 0.24-0.86) and absence of epicardial coronary artery disease (OR 0.45; 95% CI 0.22-0.93) were independently associated with inflammatory disease. Hemodynamics at rest and exercise did not differ between the groups, but peripheral oxygen extraction was lower in those with inflammatory disease, reflected by lower arterial-venous oxygen content difference (Ca-vO2) at rest (4.2±0.7 mL/dL vs 4.6±1.0 mL/dL, P<.001) and during exercise (9.3±2.2 mL/dL vs 10.4±2.2 mL/dL, P<.001) (Figure 1A), suggesting a greater peripheral deficit, and ventilatory efficiency (VE/VCO2 slope) was also more impaired (38.0±7.9 vs 36.2±7.3, P=.035). The HFpEF patients without inflammatory disease falling in the highest tertile of CRP) displayed lower Ca-vO2 during exercise, more closely resembling peripheral deficits observed in those with inflammatory disease (Figure 1B). During a median follow-up of 3.0 years, the composite outcome of all-cause deaths and HF hospitalization occurred in 127 patients (14%). Patients with HFpEF and inflammatory disease showed a higher incidence of composite outcome than those without (log-rank P=.030; Figure 2). Patients with inflammatory disease had higher risk of composite outcome compared to those without in adjusted analyses (HR 1.93; 95% CI 1.15-3.23), which was primarily attributable to higher risk of HF hospitalization (HR 2.85; 95% CI 1.08-7.52). Conclusion Patients with HFpEF and primary inflammatory disease have similar hemodynamic derangements but greater peripheral deficits in oxygen transport and higher risk for adverse outcome compared to those without.

Influence of Inner Crucible Radius Variation on the Thermal Field and Oxygen Transport in the Melt During the Growth of Silicon by Continuous Czochralski Method

Influence of Inner Crucible Radius Variation on the Thermal Field and Oxygen Transport in the Melt During the Growth of Silicon by Continuous Czochralski Method

Development of Grooves in Gas Diffusion Layers for PEM Fuel Cells Considering Mechanisms of Oxygen Transport and Water Drainage

Development of Grooves in Gas Diffusion Layers for PEM Fuel Cells Considering Mechanisms of Oxygen Transport and Water Drainage

Overcoming the Limitation of Ionomers on Mass Transport and Pt Activity to Achieve High-Performing Membrane Electrode Assembly.

The membrane electrode assembly (MEA) is one of the critical components in proton exchange membrane fuel cells (PEMFCs). However, the conventional MEA cathode with a covered-type catalyst/ionomer interfacial structure severely limits oxygen transport efficiency and Pt activity, hardly achieving the theoretical performance upper bound of PEMFCs. Here, we design a noncovered catalyst/ionomer interfacial structure with low proton transport resistance and high oxygen transport efficiency in the cathode catalyst layer (CL). This noncovered interfacial structure employs the ionomer cross-linked carbon particles as long-range and fast proton transport channels and prevents the ionomer from directly covering the Pt/C catalyst surface in the CL, freeing the oxygen diffusion process from passing through the dense ionomer covering layer to the Pt surface. Moreover, the structure improves oxygen transport within the pores of the CL and achieves more than 20% lower pressure-independent oxygen transport resistance compared to the covered-type structure. Fuel-cell diagnostics demonstrate that the noncovered catalyst/ionomer interfacial structure provides exceptional fuel-cell performance across the kinetic and mass transport-limited regions, with 77% and 67% higher peak power density than the covered-type interfacial structure under 0 kPagauge of oxygen and air conditions, respectively. This alternative interfacial structure provides a new direction for optimizing the electrode structure and improving mass-transport paths of MEA.