High Oxygen Flux Research Articles

Physical and mechanical properties of nano-modified polybenzoxazine nanocomposite laminates: Pre-flight tests before exposure to low Earth orbit

Polybenzoxazine (PBZ) formulations based on commercial components and modified with polyhedral oligomeric silsesquioxanes (POSS, 5 wt% and 10 wt%) have been scaled up for industrialisation, and their processing characteristics determined using thermal analysis and rheometry. The ultimate glass transition temperatures for the cured PBZ resins are increased by catalysis and by the incorporation of POSS. Carbon fibre reinforced polymer (CFRP) laminates (500 mm × 500 mm x 3 mm) were manufactured using resin transfer moulding and subjected to a suite of mechanical tests. The addition of 5 wt% POSS to the PBZ formulation leads to substantial improvements in both strength (tensile, flexural, short beam shear, and compression) and modulus (tensile, flexural, and compression). The CFRP specimens were subjected to a suite of pre-flight qualification tests prior to deployment in low Earth orbit. When the CFRP laminates were exposed to <1 × 10−5 mbar and 125 °C, the total mass loss recorded for each sample was <1 wt%. The introduction of POSS at both levels of incorporation improves erosion yield following exposure to high atomic oxygen flux and the ratio of solar absorptance (α) to emittance (ε) remained constant following simulated solar exposure. The outcome was that the three PBZ CFRP samples passed their pre-flight tests.

(Digital Presentation) New Magnetron Sputtering Fabrication Process for Ba0.5Sr0.5Co0.8Fe0.2O3- δ Miec Thin Film Membranes on Porous Support for Oxygen Permeation Applications

Mixed ionic electronic conductor (MIEC) membranes provide a great route for introducing oxygen to combustion and reforming processes of new fuels such as green ammonia. Ba0.5Sr0.5Co0.8Fe0.2O3- δ (BSCF) is known to be one of the most widely utilized perovskite material applied as oxygen transport membrane, as it possesses elevated oxygen permeability up to 7 ml(STP)·min-1·cm-2 at a temperature range of 850-900°C. Application of thin MIEC films of thicknesses of around 500 nm – 5 µm allow for reduction of Ohmic resistance for transport processes and sufficient oxygen permeation at lower temperatures as compared to bulk membranes, which is of great advantage with regard to materials stability and quality of sealing. However, fabrication techniques of thin MIEC membranes staunchly influence their phase purity. Crystallinity, microstructure and correlated oxygen diffusion properties as well as stability of membrane-substrate interfaces. Physical vapour deposition (PVD) such as magnetron sputtering (MS) is successfully applied to produce a dense and pinhole-free membrane with thicknesses ranging from 100 nm nanometer to a few micrometers. Challenges due to large size porosity of the ceramic substrate were addressed by tuning of the substrate porosity, ensuring formation of a continues layer and stability of the thin membranes. In this work, we report on the influence of the MS process parameters, as well as subsequent annealing techniques of both thermal annealing (TA) and line beam Laser annealing (LA) on the microstructure of a fabricated asymmetric membrane (AsM) consisting of BSCF thin membrane on a BSCF support wit tunable pore sizes. Oxygen permeability of the AsM was investigated at high temperatures (850-900 °C). For a substrate pore size of around 3 µm, BSCF membrane thicknesses of 1 to 5 µm could be applied for fabrication of AsM, resulting in a 2-fold increase of oxygen permeability ~5 ml.min-1.cm-2 at a temperature of 900 °C as compared to a bulk BSCF support of ~2 mm thickness, whereas comparable oxygen permeation is already reached at a temperature of 700°C by the thin membrane. Contrariwise, the one with high porosity (~10 µm) required the deposition of thicker layers, which obstruct the oxygen diffusion and inhibited the permeation. The results have optimised sputtering process parameters, supports porosity and TA&/SLA parameters, are key factors for producing thin film membrane exhibiting high oxygen flux and good stability.

Multiplying Oxygen Permeability of a Ruddlesden-Popper Oxide by Orientation Control via Magnets.

Ruddlesden-Popper-type oxides exhibit remarkable chemical stability in comparison to perovskite oxides. However, they display lower oxygen permeability. We present an approach to overcome this trade-off by leveraging the anisotropic properties of Nd2 NiO4+δ . Its (a,b)-plane, having oxygen diffusion coefficient and surface exchange coefficient several orders of magnitude higher than its c-axis, can be aligned perpendicular to the gradient of oxygen partial pressure by a magnetic field (0.81 T). A stable and high oxygen flux of 1.40 mL min-1 cm-2 was achieved for at least 120 h at 1223 K by a textured asymmetric disk membrane with 1.0 mm thickness under the pure CO2 sweeping. Its excellent operational stability was also verified even at 1023 K in pure CO2 . These findings highlight the significant enhancement in oxygen permeation membrane performance achievable by adjusting the grain orientation. Consequently, Nd2 NiO4+δ emerges as a promising candidate for industrial applications in air separation, syngas production, and CO2 capture under harsh conditions.

Multiplying Oxygen Permeability of a Ruddlesden‐Popper Oxide by Orientation Control via Magnets

AbstractRuddlesden‐Popper‐type oxides exhibit remarkable chemical stability in comparison to perovskite oxides. However, they display lower oxygen permeability. We present an approach to overcome this trade‐off by leveraging the anisotropic properties of Nd2NiO4+δ. Its (a,b)‐plane, having oxygen diffusion coefficient and surface exchange coefficient several orders of magnitude higher than its c‐axis, can be aligned perpendicular to the gradient of oxygen partial pressure by a magnetic field (0.81 T). A stable and high oxygen flux of 1.40 mL min−1 cm−2 was achieved for at least 120 h at 1223 K by a textured asymmetric disk membrane with 1.0 mm thickness under the pure CO2 sweeping. Its excellent operational stability was also verified even at 1023 K in pure CO2. These findings highlight the significant enhancement in oxygen permeation membrane performance achievable by adjusting the grain orientation. Consequently, Nd2NiO4+δ emerges as a promising candidate for industrial applications in air separation, syngas production, and CO2 capture under harsh conditions.

Effects of fir-wood biochar on CH4 oxidation rates and methanotrophs in landfill cover soils packed at three different proctor compaction levels

Application of biochar to landfill cover soils can purportedly improve methane (CH4) oxidation rates, but understanding the combined effects of soil texture, compaction, and biochar on the activity and composition of the methanotrophs is limited. The amendment of wood biochar on two differently textured landfill cover soils at three compaction levels of the Proctor density was explored by analyzing changes in soil physical properties relevant to methane oxidation, the effects on CH4 oxidation rates, and the composition of the methanotrophic community. Loose soils with and without biochar were pre-incubated to equally elevate the CH4 oxidation rates. Hereafter, soils were compacted and re-incubated. Methane oxidation rates, gas diffusivity, water retention characteristics, and pore size distribution were analyzed on the compacted soils. The relative abundance of methanotrophic bacteria (MOB) was determined at the end of both the pre-incubation and incubation tests of the packed samples. Biochar significantly increased porosity at all compaction levels, enhancing diffusion coefficients. Also, a re-distribution in pore sizes was observed. Increased gas diffusivity from low compaction and amendment of biochar, though, did not reflect higher methane oxidation rates due to high diffusive oxygen fluxes over the limited height of the compacted soil specimens. All soils, with and without biochar, were strongly dominated by Type II methanotrophs. In the sandy soil, biochar amendment strongly increased MOB abundance, which could be attributed to a corresponding increase in the relative abundance of Methylocystis species, while no such response was observed in the clayey soil. Compaction did not change the community composition in either soil. Fir-wood biochar addition to landfill cover soils may not always enhance methanotrophic activity and hence reduce fugitive methane emissions, with the effect being soil-specific. However, especially in finer and more compacted soils, biochar amendment can maintain soil diffusivity above a critical level, preventing the collapse of methanotrophy.

The Importance of Precise Reaction Condition Control for the Comparison of Photocatalyst Materials on the Example of Hydrogen Peroxide Formation over Polymeric Carbon Nitrides

AbstractIn our study, we aimed to show how different reaction parameters can affect production rates using photocatalytic hydrogen peroxide formation by different polymeric carbon nitrides (PCN). For this purpose, selected materials were first compared under the same reaction conditions and compared with TiO2 (P25). We also show that different light intensities can have a different influence on seemingly similar materials. Since hydrogen peroxide production in the presence of an electron donor proceeds mainly by reduction of oxygen, we also show an influence of the oxygen flow on the formation rates. Thus, with high oxygen fluxes and high intensities of irradiated light, we were able to achieve an H2O2 concentration of 125 mM after about 25 h. Finally, the two best PCN materials were selected to measure light intensity dependence at different wavelengths up to visible light. It was found that they behaved differently at the different wavelengths and thus it could be shown that an exact specification of the reaction parameters is indispensable for comparisons in the literature.

Increasing power output and isopropanol biodegradation by trickle-bed microbial fuel cells by optimizing air relative humidity and oxygen flux at cathode

The cathode air flow rate and relative humidity (RH) of a trickle-bed microbial fuel cell (TB-MFC) were optimized using the response surface methodology to obtain a high oxygen flux and a low electrical resistance at the cathode and thereby promote the oxygen reduction reaction. Under optimal air flow rate (2.20 L/min) and RH (20%) conditions, the TB-MFC system exhibited the highest oxygen flux (3.08%/cm2‧min) and the lowest resistance (5.33 Ω); its regression model had an R2 > 0.95 and the desirability coefficient was 0.78. These results demonstrate that the optimized air flow rate and RH support high oxygen flux and low resistance at the cathode. Using biochar combined with conductive carbon black (CCB) as the cathodic catalyst and optimal cathodic operating conditions, yielded a mineralization efficiency of isopropanol of 96.9% and a power density of 555 mW/m3 at an empty bed residence time and isopropanol influx concentration of 60 s and 300 ppmv, respectively. These results suggest that isopropanol can be effectively mineralized directly into CO2 and H2O by a TB-MFC, reducing the by-product accumulation, and thus increasing the power generation of the TB-MFC. Optimizing the air flow rate and RH of the biochar/CCB-based cathode in the TB-MFC increases the oxygen flux and reduces the electrical resistance of the cathode of TB-MFC, which can thus be used to treat exhaust gases that contain organics.

LaGaO3-based composite membrane with high oxygen permeability

This study presents the demonstration of the applicability of Sr and Mg co-doped LaGaO3 (LSGM), which is representative electrolyte material for solid oxide electrochemical cells due to its exceptional oxygen ionic conductivity, as oxygen transport membranes (OTMs). Herein, the oxygen flux of a LaGaO3-based composite membrane was systematically investigated by introducing Sr and Mg co-doped LaGaO3 as an ion-conductive material for composite membranes. To enhance the compatibility of the membrane and the surface exchange kinetics, perovskite LSCF phase containing La and Sr at the A-site was adopted as an electronic constituent in the membrane and active coating layer. Thus, the secondary phase between the two phases of the ionic and electronic conductors constituting the composite membrane was not observed. The highest oxygen flux (3.6 mL cm−2 min−1) was achieved in the LaGaO3-based membrane at 900 °C. The mechanism for enhancing the oxygen permeability via the active coating layer was confirmed by deriving the surface exchange kinetics under an operating atmosphere. These promising results indicate that LSGM represents a viable substitute for the oxygen-ion conductive materials utilized in dual-phase membranes.

High oxygen production membranes by Ag catalytic surface modified BSCC perovskite

This work shows the preparation, characterisation and oxygen performance of catalytic surface modified Barium Strontium Cobalt Copper (BSCC) perovskite hollow fibres for oxygen separation from air. BSCC hollow fibres were prepared via a phase inversion and sintering method with an outer diameter of ∼ 1.28 mm and a wall thickness of ∼ 0.47 mm. Subsequently, surface modification was carried out by the deposition of Ag nanoparticles as catalyst, resulting in Ag-BSCC hollow fibres. The effect of the catalyst was significant as oxygen fluxes for the Ag-BSCC hollow fibres were always higher than those of the blank BSCC hollow fibre. The Ag-BSCC hollow fibre reached very high oxygen fluxes of 30.6 mL cm−2 min−1. The maximum oxygen flux increment of 19.4 mL cm−2 min−1 over the blank BSCC hollow fibre is one order of magnitude higher than the majority of catalyst surface modified perovskite hollow fibres to date. In addition, the surface modified Ag-BSCC hollow fibre reduced the apparent energy of activation by 46% as compared to the blank BSCC hollow fibre, thus overcoming the rate limiting step of oxygen surface reaction. A mechanism is provided for the high performance of the Ag-BSCC based on three phase transitions of the BSCC perovskite structure as ascertained by high temperature HT-XRD and the oxygen spillover effect of the Ag nanoparticles.

On the localized corrosion of AA5083 in a simulated dynamic seawater/air interface—Part 1: Corrosion initiation mechanism

Localized corrosion of the aluminium alloy AA5083-H111 in a simulated dynamic seawater/air interfacial zone and a full seawater immersion zone was investigated with electrochemical impedance spectroscopy and electrochemical noise. Al-Fe/Ti intermetallic particles (IMPs) on localized corrosion were examined with focused ion beam, transmission electron microscopy and energy dispersive x-ray spectroscopy. As compared with the full immersion zone, the interfacial zone showed higher oxide film resistance and charge transfer resistance, which was attributed to the high oxygen flux in that zone. Localized corrosion arose from IMPs that posessed an Al-Fe phase and a Ti enriched phase.

Asymmetric Ba0.5Sr0.5Co0.8Fe0.2O3-Δ Membrane for Oxygen Permeation: Synergetic Fabrication By Magnetron Sputtering Deposition and Selective Laser Annealing

The Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) mixed ionic electronic conductor (MIEC) is considered to be one of the most promising perovskite-based materials for oxygen transport exhibiting high oxygen permeability. Such oxygen-permeable perovskite membrane maybe applied to increase efficiency of combustion or reforming processes of new fuels such as green ammonia. An approach to elevate the oxygen permeability of BSCF membranes is reduction of membrane thickness, as the permeation process is mostly controlled by bulk diffusion. Since self-standing thin membranes are not sufficiently mechanically stable, asymmetric membranes consisting of a thin layer membrane deposited onto a porous bulk support are usually employed. . In this work, planar BSCF thin film membranes of 1 to 2 and 15 to 20 µm thickness were successfully synthesized by a combination of magnetron sputtering (MS) and thermal annealing (TA) and/or selective laser annealing (SLA) processes. Thin films appeared to be pinhole-free with a high crystallinity of a single perovskite phase and a microstructure that showed suitability for oxygen permeation applications. Correlations between thin film properties and MS process parameters (e.g. power, Ar/O2 ratio, pressure, etc.) and TA&/SLA parameters were established and optimised as key factors for producing thin film membrane exhibiting high oxygen flux and good stability. A variation of the oxygen flux through the BSCF asymmetric membrane as well as the porous substrate is presented as a function of temperature and also oxygen partial pressures applied to both sides of the membrane allowing for calculation of permeability of the deposited thin film. Figure 1

Scalable Formation of Highly Viable and Functional Hepatocellular Carcinoma Spheroids in an Oxygen-Permeable Microwell Device for Anti-Tumor Drug Evaluation.

For high-throughput anti-cancer drug screening, microwell arrays may serve as an effective tool to generate uniform and scalable tumor spheroids. However, microwell arrays are commonly anchored in non-oxygen-permeable culture plates, leading to limited oxygen supply for avascular spheroids. Herein, a polydimethylsiloxane (PDMS)-based oxygen-permeable microwell device is introduced for generating highly viable and functional hepatocellular carcinoma (HCC) spheroids. The PDMS sheets at the bottom of the microwell device provide a high flux of oxygen like in vivo neighboring hepatic sinusoids. Owing to the better oxygen supply, the generated HepG2 spheroids are larger in size and exhibit higher viability and proliferation with less cell apoptosis and necrosis. These spheroids also exhibit lower levels of anaerobic cellular respiration and express higher levels of liver-related functions. In anti-cancer drug testing, spheroids cultured in PDMS plates show a significantly stronger resistance against doxorubicin because of the stronger stem-cell and multidrug resistance phenotype. Moreover, higher expression of vascular endothelial growth factor-A produces a stronger angiogenesis capability of the spheroids. Overall, compared to the spheroids cultured in conventional non-oxygen-permeable plates, these spheroids can be used as a more favorable model for early-stage HCCs and be applied in high-throughput anti-cancer drug screening.

Impact of Variability in Precipitation Patterns on the Geochemistry of Pyritic Uranium Tailings Rehabilitated with Saturated Cover Technology

Increasing variability in precipitation patterns is expected to result from climate change in Canada. This effect has the potential to affect the performances of saturated covers in inhibiting acid rock drainage (ARD) and metal leaching (ML) processes. Because ARD and ML may cause the release of deleterious chemical species into the environment, such climate-change-driven impact was investigated using trickle leach columns. The physical, chemical, and mineralogical characteristics of the tailings as well as chemical composition of the leachate were measured before and after the column study. Results from the experiment showed that higher variability in precipitation regimes could enhance leaching of uranium. Leaching ranged from 67.1 to 90.1% of the total amount of U, with greater values associated with higher variability in precipitation patterns. Lower water levels and prolonged drought periods led to higher oxygen fluxes to the U tailings and dissolution of carbonate-bearing minerals. The release of carbonates could have enhanced uranium leaching through the formation of stable uranium-carbonate complexes in solution. Overall, this study shows that water level variation caused by varying precipitation patterns can significantly affect the drainage chemistry of saturated cover systems for which the level fluctuates freely near the tailings–cover interface.

Modification of Ruddlesden-Popper-type Nd2-xNi0.75Cu0.2M0.05O4±δ by the Nd-site cationic deficiency and doping with Sc, Ga or In: Crystal structure, oxygen content, transport properties and oxygen permeability

Nd2-xNi0.75Cu0.2M0.05O4±δ (x ​= ​0 and 0.1; M ​= ​Sc, Ga, and In) Ruddlesden-Popper-type oxides are obtained by a sol-gel route and characterized concerning phase composition and crystal structure. It is found that the largest In3+ cannot be effectively introduced into the structure, while Nd stoichiometric and cation-deficient Nd2-xNi0.75Cu0.2Sc0.05O4±δ and Nd2-xNi0.75Cu0.2Ga0.05O4±δ (x ​= ​0; 0.1) can be obtained as single-phase materials. Systematic characterization of the crystal structure at high temperatures, oxygen content, as well as transport properties reveals that while the Nd-site deficiency has rather negligible influence on the structure, it causes a substantial decrease of the oxygen content, which at high temperatures leads to a change of the dominant type of defects from the oxygen interstitials to the vacancies for Nd1.9Ni0.75Cu0.2Sc0.05O4±δ and Nd1.9Ni0.75Cu0.2Ga0.05O4±δ. The Nd-site deficiency also causes a decrease of the total conductivity. Importantly, all the examined materials exhibit full chemical stability in CO2 atmosphere, which together with moderate thermal expansion makes them good candidates for the oxygen transport membranes, which can be used e.g. in the air separation technologies. The selected Sc- and Ga-doped compounds evaluated as ceramic membranes show relatively high oxygen fluxes, with the highest value of 0.78 ​mL ​cm-2 min-1 at ca. 880 ​°C registered for 0.9 ​mm thick, dense Nd1.9Ni0.75Cu0.2Ga0.05O4±δ membrane.

Hyperglycemia in a type 1 Diabetes Mellitus model causes a shift in mitochondria coupled-glucose phosphorylation and redox metabolism in rat brain

Hyperglycemia associated with Diabetes Mellitus type 1 (DM1) comorbidity may cause severe complications in several tissues that lead to premature death. These dysfunctions are related, among others, to redox imbalances caused by the uncontrolled cellular levels of reactive oxygen species (ROS). Brain is potentially prone to develop diabetes complications because of its great susceptibility to oxidative stress. In addition to antioxidant enzymes, mitochondria-coupled hexokinase (mt-HK) plays an essential role in maintaining high flux of oxygen and glucose to control the mitochondrial membrane and redox potential in brain. This redox control is critical for healthy conditions in brain and in the pathophysiological progression of DM1. The mitochondrial and mt-HK contribution in this process is essential to understand the relationship between DM1 complications and the management of the cellular redox balance. Using a rat model of one month of hyperglycemia induced by a single administration intraperitoneally of streptozotocin, we showed in the present work that, in rat brain mitochondria, there is a specifically reduction of the mitochondrial complex I (CI) activity and an increase in the activity of the antioxidant enzyme thioredoxin reductase, which are related to decreased hydrogen peroxide generation, oxygen consumption and mt-HK coupled-to-OxPhos activity via mitochondrial CI. Surprisingly, DM1 increases respiratory parameters and mt-HK activity via mitochondrial complex II (CII). This way, for the first time, we provide evidence that early progression of hyperglycemia, in brain tissue, changes the coupling of glucose phosphorylation at the level of mitochondria by rearranging the oxidative machinery of brain mitochondria towards CII dependent electron harvest. In addition, DM1 increased the production of H2O2 by α-ketoglutarate dehydrogenase without causing oxidative stress. Finally, DM1 increased the oxidation status of PTEN and decreased the activation of NF-kB in DM1. These results indicate that this reorganization of glucose-oxygen-ROS axis in mitochondria may impact turnover of glucose, brain amino acids, redox and inflammatory signaling. In addition, this reorganization may be involved in early protection mechanisms against the development of cognitive degeneration and neurodegenerative disease, widely associated to mitochondrial CI deficits.

Ground testing of an on-orbit atomic oxygen flux and ionizing radiation dose sensor based on material degradation by the space environment

Atomic oxygen is the predominant neutral species in the low Earth orbit environment and is considered to be one of the main hazards to spacecraft materials. The pursuit nowadays of satellite projects toward very low Earth orbit missions, results in exposure of these spacecraft to extremely high atomic oxygen flux. In geosynchronous Earth orbit spacecraft are exposed to charged particles and ionizing radiation which may affect their electronics. Therefore, obtaining accurate on-orbit atomic oxygen flux and total ionizing dose data will contribute to the design of the next generation of spacecraft by facilitating reliable prediction of material and electronics durability for a specific mission. Atomic oxygen flux and ionizing radiation can be measured by a variety of techniques which are either extremely expensive, require retrieval of samples, or difficult to implement on board small spacecraft. In this study, we present validation test results of the on-orbit materials degradation detector, in a series of ground-based measurements. The on-orbit materials degradation detector is based on photovoltaic cells and can measure real-time space environment components. The goal of this study is to validate the on-orbit materials degradation detector's accuracy during atomic oxygen flux measurements under severe conditions and to calibrate it for total ionizing dose measurements. The validation of the on-orbit materials degradation detector is a step toward its integration with the THERME experiment, which was developed in order to provide real-time ageing measurements of thermal control coatings. The combined THERME - on-orbit materials degradation detector will allow correlation between real-time space environment effects and ageing of materials. The results show the versatility of the on-orbit materials degradation detector, i.e. its ability to measure real-time and accurate atomic oxygen fluxes while being exposed to extreme thermal cycles, its ability for total ionizing dose measurements, as well as its real-time material degradation detection capability.

P3476High-resolution respirometry reveals enhanced myocardial mitochondrial ketone oxidation after fasting and ventricular unloading

Abstract Background Impairment of myocardial mitochondrial function is regarded as an established pathomechanism in heart failure. Enhanced oxidation of ketone bodies may potentially exert protective effects on myocardial function. High-resolution respirometry (HRR) resembles a gold-standard methodology to determine myocardial mitochondrial metabolism and oxidative function but has not been validated for ketone substrates yet. Purpose We hypothesized that (1) quantification of ketone body oxidative capacity (OC) in myocardium utilizing ex-vivo HRR is feasible and that (2) ketone-associated OC is elevated after fasting and under conditions of chronic mechanical ventricular unloading. Methods We established new HRR (Oxygraph-2k) protocols, measuring oxygen flux generated by oxidation of the ketone substrates beta-hydroxybutyrate (HBA) and acetoacetate (ACA). Ketone protocols were then applied to twelve C57BL/6 mice' (of which six were fasted for 16h) left ventricular and right liver lobe tissue, as well as to eleven terminal heart failure patients' left ventricular tissue, harvested at heart transplantation. Heart transplant recipients were subdivided into patients with left ventricular assist device prior to transplantation (LVAD group, n=6) or no unloading prior to transplantation (HTX group, n=5). Results In non-fasted rodent hearts, HBA yielded an OC of 25±4 pmol/(s*mg tissue) above basal respiration, when applied as sole substrate (21±11 pmol/(s*mg) in liver). ACA alone did not induce oxygen flux, but ACA+succinate yielded 229% higher oxygen flux than succinate alone in state III (146±32 vs 44±12 pmol/(s*mg); p=0.0003). When titrated after succinate, ACA increased OC by 93±25 pmol/(s*mg) (p=0.0003). In 16h-fasted rodent hearts, HBA-supported OC was 27% higher (41±3 vs 52±9 pmol/(s*mg); p=0.04), while OC with ACA+succinate was unchanged (p=0.60). In rodent liver, no oxygen flux was induced by ACA, reflecting absence of 3-oxoacid CoA-transferase. However, HBA-supported OC was 118% higher in fasted liver (37±13 vs 57±13 pmol/(s*mg); p=0.03). In humans, left ventricular unloading was not associated with altered myocardial OC for fatty acids and glycolytic substrates (standard protocol, p=0.13), but HBA-supported OC was 39% higher in the LVAD group compared to the HTX group (54±12 vs 39±9 pmol/(s*mg), p=0.04). Conclusion Quantification of ketone body OC with HRR is feasible in permeabilized myocardial fibers. Applying this novel method revealed increased HBA-supported myocardial mitochondrial respiration after fasting and chronic left ventricular unloading. These data support a concept of enhanced ketone oxidation following ventricular unloading in myocardial mitochondria. Our findings facilitate new studies on myocardial ketone turnover and the interaction of mitochondrial ketone metabolism with cardiac performance. Acknowledgement/Funding CRC 1116, Research commission of the University Hospital Düsseldorf

MIEC-type ceramic membranes for the oxygen separation technology

Mixed ionic-electronic conducting ceramic membrane-based oxygen separation technology attracts great attention as a promising alternative for oxygen production. The oxygen-transport membranes should not only exhibit a high oxygen flux but also show good stability under CO2-containing atmospheres. Therefore, designing and optimization, as well as practical application of membrane materials with good CO2 stability is a challenge. In this work, apart from discussion of literature data, authors’ own results are provided, which are focused on materia - related issues, including development of electrode materials exhibiting high ionic and electronic conductivities.

Evaluation of silicon membranes for extracorporeal membrane oxygenation (ECMO).

While extracorporeal membrane oxygenation (ECMO) is a valuable therapy for patients with lung or heart failure, clinical use of ECMO remains limited due to hemocompatibility concerns with pro-coagulatory hollow fiber membrane geometries. Previously, we demonstrated the feasibility of silicon nanopore (SNM) and micropore (SμM) membranes for transport between two liquid-phase compartments in blood-contacting devices. Herein, we investigate various pore sizes of SNM and SμM membranes - alone or with a polydimethylsiloxane (PDMS) protective coating - for parameters that determine suitability for gas exchange. We characterized the bubble or rupture point of these membranes to determine sweep gas pressures at which gas emboli would form. The smallest pore size SNM and the SμM with PDMS coating could be pressurized in excess of 260 cmHg without rupture, which is comparable to hollow fiber sweep gas pressures. Oxygen flux for the SμM with and without PDMS was insignificantly different at 0.0306 ± 0.0028 and 0.0297 ± 0.0012mL/min, respectively, while SNM flux was significantly lower at 0.0149 ± 0.0040mL/min. However, the area-normalized mass transfer coefficient of the SNM was 338 ± 54mL O2 m-2min-1 cmHg-1 - an order of magnitude higher than that of the SμM with and without PDMS (57.3 ± 5.5 and 55.6 ± 2.2mL O2 m-2min-1 cmHg-1). Ultimately, we conclude that SμM-PDMS may make effective membranes for ECMO, since they are both mechanically robust and capable of high oxygen flux.

Perovskite hollow fiber membranes supported in a porous and catalytically active perovskite matrix for air separation

Abstract Mixed conducting perovskite membranes have attracted much research interest for use in air separation. However, the application of perovskite hollow fiber membranes is limited by their brittleness. Herein, the fiber bundling in a perovskite matrix is reported to overcome the physical weakness of the individual perovskite hollow fiber membranes. This has been achieved by binding these hollow fibers into one matrix using a porous binder made from the same membrane material, i.e., La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) perovskite. The bending force for one individual LSCF hollow fiber is 2.18 N for a fixed length of 4 cm; in contrast, the bending forces for the LSCF bundle in the same length including 3, 5, 8, and 10 single LSCF hollow fibers are 6.80, 11.77, 23.97, and 39.02 N, respectively. The membrane bundle was evaluated for air separation using a sweep gas mode by passing the air in the shell side and argon through the fiber lumen operated from 800 to 1000 °C. The oxygen flux through the single LSCF hollow fiber at 950 °C was 0.26 mL cm−2 min−1 (standard conditions) but the bundle gave a higher flux improved by 76% up to 0.46 mL cm−2 min−1 under similar testing conditions due to the porous matrix with enhanced surface reaction kinetics. The resultant membrane bundle demonstrates exceeding performance for air separation in terms of high oxygen flux, mechanical strength, and thermal stability for an easy scale-up.