Electrochemical Study on MgO as an Additive in Molten Li2CO3-Na2CO3 for Molten Carbonate Fuel Cells

This study investigates the effect of MgO as an additive in molten Li2CO3-Na2CO3 electrolyte for molten carbonate fuel cells through electrochemical analyses. Addition of MgO (1~5 mol%) increased the electrochemical response in cyclic voltammogram of peroxide in molten Li2CO3-Na2CO3. The diffusion coefficient of peroxide in molten Li2CO3-Na2CO3 containing MgO was determined via the comparison between the peak currents of cyclic voltammograms from microwire electrode and macrowire electrode. The addition of MgO did not impact the diffusion coefficient, indicating that the increase in the electrochemical response with the addition of MgO might be attributed to the increase in the peroxide concentration. The change in peroxide concentration was also confirmed by electrochemical impedance analyses, which exhibited a decrease in the exchange current density. The increase in the concentration of peroxide with the addition of MgO might be associated with the high thermal decomposition constant of MgCO3, implying the high concentration of oxide ion in the molten Li2CO3-Na2CO3. This study suggests that MgO might be an effective additive for increasing the oxygen solubility in the molten Li2CO3-Na2CO3, and subsequently for enhancing the performance of molten carbonate fuel cells.

Optimized Dissolved Oxygen Fuzzy Control for Recombinant Escherichia coli Cultivations

Due to low oxygen solubility and mechanical stirring limitations of a bioreactor, ensuring an adequate oxygen supply during a recombinant Escherichia coli cultivation is a major challenge in process control. Under the light of this fact, a fuzzy dissolved oxygen controller was developed, taking into account a decision tree algorithm presented in the literature, and implemented in the supervision software SUPERSYS_HCDC. The algorithm was coded in MATLAB with its membership function parameters determined using an Adaptive Network-Based Fuzzy Inference System tool. The controller was composed of three independent fuzzy inference systems: Princ1 and Princ2 assessed whether there would be an increment or a reduction in air and oxygen flow rates (respectively), whilst Delta estimated the size of these variations. To test the controller, simulations with a neural network model and E. coli cultivations were conducted. The fuzzification of the decision tree was successful, resulting in smoothing of air and oxygen flow rates and, hence, in an attenuation of dissolved oxygen oscillations. Statistically, the average standard deviation of the fuzzy controller was 2.45 times lower than the decision tree (9.48%). Results point toward an increase in the flow meter lifespan and a possible reduction of the metabolic stress suffered by E. coli during the cultivation.

Dynamic model of dissolved oxygen in intensive concrete pond of white leg shrimp (Litopenaeus vannamei) in Bomo Village, East Java

This study is to understand a simple model of dissolved oxygen (DO) and other water quality factors that affect it in two seasons in intensive white leg shrimp ponds. Water quality parameters in the dry and rainy seasons in several ponds were sampled daily, including temperature, pH, (DO), salinity, twice a week, including ammonium, nitrite, nitrate, orthophosphate, total alkalinity, and total bacteria. Besides daily, dissolved oxygen is also measured before the harvest every two hours by using dark bottles and light bottles. Pond water quality parameters are still suitable for white shrimp culture. Daily DO shrimp ponds form a polynomial regression model. DO in light bottles constructed a quadratic regression model, DO in dark bottles created a linear regression pattern, with a DO reduction rate of 0.6338 mg−l per hour. During one of the shrimp cultures, the DO model showed an inverse quadratic equation with the lowest oxygen solubility level on day 57. DO was positively correlated with changes in salinity and transparency and negatively related to ammonium, nitrate, phosphate, total alkalinity, and total bacteria count.

The role of oxygen-permeable ionomer for polymer electrolyte fuel cells

In recent years, considerable research and development efforts are devoted to improving the performance of polymer electrolyte fuel cells. However, the power density and catalytic activities of these energy conversion devices are still far from being satisfactory for large-scale operation. Here we report performance enhancement via incorporation, in the cathode catalyst layers, of a ring-structured backbone matrix into ionomers. Electrochemical characterizations of single cells and microelectrodes reveal that high power density is obtained using an ionomer with high oxygen solubility. The high solubility allows oxygen to permeate the ionomer/catalyst interface and react with protons and electrons on the catalyst surfaces. Furthermore, characterizations of single cells and single-crystal surfaces reveal that the oxygen reduction reaction activity is enhanced owing to the mitigation of catalyst poisoning by sulfonate anion groups. Molecular dynamics simulations indicate that both the high permeation and poisoning mitigation are due to the suppression of densely layered folding of polymer backbones near the catalyst surfaces by the incorporated ring-structured matrix. These experimental and theoretical observations demonstrate that ionomer’s tailored molecular design promotes local oxygen transport and catalytic reactions.

Biomimetic oxygen delivery nanoparticles for enhancing photodynamic therapy in triple-negative breast cancer

Background Triple-negative breast cancer (TNBC) is a kind of aggressive breast cancer with a high rate of metastasis, poor overall survival time, and a low response to targeted therapies. To improve the therapeutic efficacy and overcome the drug resistance of TNBC treatments, here we developed the cancer cell membrane-coated oxygen delivery nanoprobe, CCm–HSA–ICG–PFTBA, which can improve the hypoxia at tumor sites and enhance the therapeutic efficacy of the photodynamic therapy (PDT), resulting in relieving the tumor growth in TNBC xenografts. Results The size of the CCm–HSA–ICG–PFTBA was 131.3 ± 1.08 nm. The in vitro 1O2 and ROS concentrations of the CCm–HSA–ICG–PFTBA group were both significantly higher than those of the other groups (P < 0.001). In vivo fluorescence imaging revealed that the best time window was at 24 h post-injection of the CCm–HSA–ICG–PFTBA. Both in vivo 18F-FMISO PET imaging and ex vivo immunofluorescence staining results exhibited that the tumor hypoxia was significantly improved at 24 h post-injection of the CCm–HSA–ICG–PFTBA. For in vivo PDT treatment, the tumor volume and weight of the CCm–HSA–ICG–PFTBA with NIR group were both the smallest among all the groups and significantly decreased compared to the untreated group (P < 0.01). No obvious biotoxicity was observed by the injection of CCm–HSA–ICG–PFTBA till 14 days. Conclusions By using the high oxygen solubility of perfluorocarbon (PFC) and the homologous targeting ability of cancer cell membranes, CCm–HSA–ICG–PFTBA can target tumor tissues, mitigate the hypoxia of the tumor microenvironment, and enhance the PDT efficacy in TNBC xenografts. Furthermore, the HSA, ICG, and PFC are all FDA-approved materials, which render the nanoparticles highly biocompatible and enhance the potential for clinical translation in the treatment of TNBC patients.

A relationship between temperature, oxygen dissolved in blood and viral infections

An investigation is made on the environmental factors that may determine the seasonal cycle of respiratory affections. The driving role of temperature is examined, for its inverse synergism with the dissolution of oxygen in human plasma. Two best-fit equations are discussed to interpolate the experimental data about the oxygen solubility and the saturation levels reached at various temperatures, referring to the value of the basic alveolar temperature. A vulnerable condition is when the airways temperature is lowered, e.g. breathing cold air, or increasing the breathing frequency. In winter, the upper airways reach lower temperatures and greater oxygen concentrations; the opposite occurs in summer. As low temperatures increase the dissolution of oxygen in plasma, and blood oxidation favours viral activity, an explanation is given to the seasonality of infections affecting the respiratory system.

Climate and Human-Driven Variability of Summer Hypoxia on a Large River-Dominated Shelf as Revealed by a Hypoxia Index

Coastal hypoxia has become common especially in large river dominated coastal ecosystems. To better quantify the severity of hypoxia and the contribution of hypoxia drivers, we applied principal component analysis (PCA) on observable properties from eight summer hypoxia events in the East China Sea and defined the first principal component as the hypoxia index (HI). Multiple linear regression showed that the HI significantly correlated with three direct hypoxia drivers including water column stratification, subsurface water residence time, and respiration rates, which accounted for 5.7, 55.3, and 34.5%, respectively, of the total variance of PCA derived HI. We further reconstructed the HI over the past 60 years using available long-term data of stratification, model-derived residence times and respiration rates. The results show that summer hypoxia has become more severe since the 1960s. ENSO and global warming may have exacerbated hypoxia by affecting the river discharge, resulting in freshening in the plume-impacted shelf area, while anthropogenic activities may have exacerbated hypoxia by elevating fluvial nutrient concentrations, resulting in higher respiration rates. In addition, warming of the bottom water from the Kuroshio Current accounts for an additional increasing rate for HI, which made hypoxia more severe by means of decreasing oxygen solubility. Overall, our results indicate that stratification, water residence and oxygen solubility resulting from climate change can explain about 80% while higher respiration resulting from higher nutrient inputs can explain about 20% of the variation in the severity of hypoxia during the past half century.

Biomimetic Oxygen Delivery Nanoparticles for Enhancing Photodynamic Therapy in Triple-negative Breast Cancer

Background Triple-negative breast cancer (TNBC) is a kind of aggressive breast cancer with a high rate of metastasis, poor overall survival time, and a low response to targeted therapies. To improve the therapeutic efficacy and overcome the drug resistance of TNBC treatments, here we developed the cancer cell membrane-coated oxygen delivery nanoprobe, CCm-HSA-ICG-PFTBA, which can improve the hypoxia at tumor sites and enhance the therapeutic efficacy of the photodynamic therapy (PDT), resulting in relieving the tumor growth in TNBC xenografts. Results The size of the CCm-HSA-ICG-PFTBA was 131.3 ± 1.08 nm. The in vitro 1O2 and ROS concentrations of the CCm-HSA-ICG-PFTBA group were both significantly higher than those of the other groups (P < 0.001). In vivo fluorescence imaging revealed that the best time window was at 24 h post-injection of the CCm-HSA-ICG-PFTBA. Both in vivo 18F-FMISO PET imaging and ex vivo immunofluorescence staining results exhibited that the tumor hypoxia was significantly improved at 24 h post-injection of the CCm-HSA-ICG-PFTBA. For in vivo PDT treatment, the tumor volume and weight of the CCm-HSA-ICG-PFTBA with NIR group were both the smallest among all the groups and significantly decreased compared to the untreated group (P < 0.01). No obvious biotoxicity was observed by the injection of CCm-HSA-ICG-PFTBA till 14 days. Conclusions By using the high oxygen solubility of perfluorocarbon (PFC) and the homologous targeting ability of cancer cell membranes, CCm-HSA-ICG-PFTBA can target tumor tissues, mitigate the hypoxia of the tumor microenvironment, and enhance the PDT efficacy in TNBC xenografts. Furthermore, the HSA, ICG, and PFC are all FDA-approved materials, which render the nanoparticles highly biocompatible and enhance the potential for clinical translation in the treatment of TNBC patients.

Perfluorinated organics regulating Li2O2 formation and improving stability for Li–oxygen batteries

Perfluorotributylamine, an artificial blood, is introduced into lithium–oxygen batteries due to its excellent oxygen solubility, achieving superior high capacity and long stability.