Improved Oxygen Availability Research Articles

Experimental Design of High-Performing Open-Cathode Polymer Electrolyte Membrane Fuel Cells

Open-cathode polymer electrolyte membrane fuel cells (PEMFCs) utilize a unique air-cooled system design to eliminate the humidifiers, air compressor, and liquid cooling loop of conventional, liquid-cooled PEMFC systems, thereby greatly reducing system cost. However, the open-cathode PEMFC performance is restricted by poor humidification, high membrane and charge transfer resistances, and overheating due to inefficient thermal and water management. This work aims to strategically modify the membrane electrode assembly (MEA) design to overcome these issues and achieve high open-cathode PEMFC performance that approaches that of liquid-cooled systems. The use of thinner membrane along with short side chain ionomer is found to elevate the cell performance due to increased water retention at the cathode catalyst layer (CCL) and decreased ohmic losses. Thinner gas diffusion layers with high porosity enable additional cell performance increment by improving oxygen availability at the CCL. An overall current density rise of 88% at 0.6 V and 53% at 0.4 V is achieved by the strategically designed MEA for open-cathode cells. The enhanced power density enabled by the custom MEA can both reduce the stack cost and expand the power range of open-cathode PEMFCs, thus expanding their potential use for low-cost fuel cell system applications.

P-412 Long-term in vitro dynamic culture of bovine ovarian cortical tissue (BOCT) increases follicle growth, viability and AMH secretion

Abstract Study question Does improved oxygen availability and biomechanical stimulation during long-term dynamic in vitro culture of BOCT enhance secondary follicles growth and health? Summary answer Long-term dynamic versus static in vitro culture of BOCT increases the proportion, viability and AMH secretion of growing follicles. What is known already A limiting factor in multistep in vitro folliculogenesis is the low yeld of healthy secondary follicles after ovarian cortical tissue culture. We previously reported that dynamic in vitro culture of ovarian cortical tissue for 7 days in a newly designed perifusion bioreactor (patent 102020000027290) enhances follicle growth and health compared to conventional static culture. The bovine represents a valuable animal model to study early folliculogenesis in vitro. Study design, size, duration Bovine ovaries (age 8-24 months) were collected from slaughterhouse. BOCT strips from the same ovary were cultured for 14 days in perifusion bioreactors (PB, dynamic culture) and conventional dishes (CD, static culture). BOCT cultured in both PB and CD was monitored by collecting spent media every 2 days and through histology, live-dead confocal analysis at the end of culture. Participants/materials, setting, methods BOCT slices (0.5mm thick) were obtained by a custom tissue slicer, chopped into 1x1mm strips and cultured in group of 10 under in PB and CD. Follicle stages and quality in fresh (D0) and cultured tissues were evaluated by histology (hematoxylin-eosin staining), follicle viability was estimated by labelling with live-dead far-red and propidium iodide at the confocal microscope. Whole tissue viability (spectrophotometric LDH assays) and AMH secretion (mass spectrometry) were evaluated on spent media. Main results and the role of chance Overall, 939 follicles were analyzed (histology, 338; viability, 601). Day 0-Follicle stages: primordial, 82.4%; primary, 13.2%; secondary, 4.4%; follicle quality: grade 1-2, 37,6%; grade 3, 62,4%; live follicles: 94.3%. Day 14: PB vs CD - Follicle stages: primordial, 3.8 vs 5.7%,NS; primary, 75 vs 86.1%, NS; secondary, 21.2 vs 8.2%, P < 0.05; follicle quality: grade I/II, 70 vs 18.9%, P < 0.01; grade III, 30 vs 81.1%, P < 0.01; live follicles 62.6 vs 35.3%, P < 0.01. LDH activity in PB was markedly lower than in CD at all culture times (PB14d 150.5 nmol vs CD14d 233.1 nmol). During 14 days culture, AMH secretion continuously increases in PB (1700 picomol/Vtot) whereas in CD it markedly decreases during culture, falling down at very low values at the end of culture (67 picomol/Vtot). Findings indicate that the increased transport of solutes and dissolved oxygen, and the biomechanical stimulation in our novel dynamic bioreactor are key factors during ovarian tissue culture. Analysis of LDH and AMH levels in spent media confirm that dynamic culture better mantains general tissue health and promote a better functionality of growing follicles. Limitations, reasons for caution Although the bovine is considered a reliable model for human folliculogenesis, the study should be validated on human ovarian tissue. Wider implications of the findings Poor yield of secondary follicles during organ culture is a limiting step in the in vitro production of mature oocytes from primordial follicles. The use of a newly developed dynamic bioreactor for long-term culture could represent a valuable tool for in vitro multistep folliculogenesis. Trial registration number not applicable

Air–liquid interface cultures trigger a metabolic shift in intestinal epithelial cells (IPEC-1)

An improved oxygen availability in air–liquid interface (ALI) cultures of enterocytes of the small intestine seems to be primarily responsible for morphological, metabolic, and functional changes. Intestinal porcine epithelial cells 1 (IPEC-1) are less investigated and are rarely used as model for intestinal barrier but showed a profound change of cell shape during ALI cultivation. We aim to answer the following question: Are the observed morphological effects accompanied by changes in metabolic function? A microarray analysis of submerged culture (SMC) and ALI cultures identified 830 significantly regulated genes. Subsequent functional clustering revealed alterations in 31 pathways, with the highest number of regulated genes in metabolic pathways, carbon metabolism, glycolysis, and hypoxia-inducible factor (HIF) signaling. Furthermore, HIF-1α as a mediator of a metabolic switch between glycolysis and oxidative phosphorylation showed a trend of increased mRNA levels in ALI in contrast to a reduced nuclear HIF-1α content in the nucleus. Candidate genes of oxidative phosphorylation such as a mitochondrial marker exhibited enhanced mRNA levels, which was confirmed by western blot analysis. Cytochrome C oxidase (COX) subunit 5B protein was decreased in ALI, although mRNA level was increased. The oxidation of ferrocytochrome C to ferricytochrome C was used for detection of cytochrome C oxidase activity of isolated mitochondria and resulted in a trend of higher activity in ALI. Furthermore, quantification of glucose and lactate concentrations in cell culture medium revealed significantly reduced glucose levels and decreased lactate production in ALI. To evaluate energy metabolism, we measured cellular adenosine triphosphate (ATP) aggregation in homogenized cell suspensions showing similar levels. However, application of the uncoupling agent FCCP reduced ATP levels in ALI but not in SMC. In contrast, blocking with 2-desoxy-d-glucose (2DG) significantly reduced ATP content in ALI and SMC. These results indicate a metabolic shift in IPEC-1 cultured under ALI conditions enhancing oxidative phosphorylation and suppressing glycolysis.

The Post Coronavirus Disease-19 Pandora-Box: Future Directions for Critical Care in Low and Medium-Income Countries

The novel Coronavirus disease-19, caused by the Severe Acute Respiratory Syndrome-Coronavirus-2 virus posed a worldwide public health emergency and remains a large health burden till date in some continents, causing a significant morbidity and mortality among the critically-ill, not sparing the low and medium-income countries. The critical care surge in most countries exposed the unpreparedness and “struggling” health systems of these countries, including Low and medium-income countries in containing the epidemic. The suddenness of Coronavirus disease in China is suggestive that another “Pathogen X” epidemic may occur. In addition, the increasing global terrorism index may precipitate another epidemic secondary to a bioterrorism contagion. In mitigating this, however, lessons learnt from the management of the critically-ill patients with the Coronavirus disease may assist the low and medium-income countries in charting the future directions of critical care in the event of any Post Coronavirus disease public health challenge. The import of systems approach and collaboration with development partners cannot be over-emphasized, alongside increasing critical care beds and improving oxygen availability and accessibility. Finally, changing the narrative of “struggling” health systems of developing countries by addressing the major debilitating factors, including the issue of critical care workforce and training is needed. The new Essential and Emergency Critical Care training program is proffered. Furthermore, offering skilled healthcare workers adequate remuneration and other incentives to guard against their migration to “greener pastures” may help the low and middle-income countries retain critical care specialists in preparing for any sudden Post-Coronavirus disease public health emergency.

Limited Utility of Self-made Oxygen Generators Assembled From Everyday Commodities During the COVID-19 Pandemic.

The current COVID-19 pandemic has aggravated pre-existing oxygen supply gaps all over the world. In fact, oxygen shortages occurred in affluent areas with highly developed healthcare systems. The state-of-affairs created much suffering and resulted in potentially preventable deaths. Meanwhile, several international activities have been initiated to improve oxygen availability in the long-term by creating new networks of oxygen plants and supply channels. However, disasters such as the current pandemic may require rapid, autarkic oxygen production. Therefore, we determined whether oxygen resilience could conceivably be improved through self-made oxygen generators using material that is easily available even in remote areas. The team comprised engineers and physicians with hands-on experience in low- and middle-income countries. We constructed and tested self-made setups for water hydrolysis and membrane-based oxygen purification. We must conclude, however, that the massive amounts of oxygen patients with COVID-19 require cannot be reasonably met with such simple measures, which would require high efforts and hold potential risks.

Therapeutic Modification of Hypoxia

Regions of reduced oxygenation (hypoxia) are a characteristic feature of virtually all animal and human solid tumours. Numerous preclinical studies, both in vitro and in vivo, have shown that decreasing oxygen concentration induces resistance to radiation. Importantly, hypoxia in human tumours is a negative indicator of radiotherapy outcome. Hypoxia also contributes to resistance to other cancer therapeutics, including immunotherapy, and increases malignant progression as well as cancer cell dissemination. Consequently, substantial effort has been made to detect hypoxia in human tumours and identify realistic approaches to overcome hypoxia and improve cancer therapy outcomes. Hypoxia-targeting strategies include improving oxygen availability, sensitising hypoxic cells to radiation, preferentially killing these cells, locating the hypoxic regions in tumours and increasing the radiation dose to those areas, or applying high energy transfer radiation, which is less affected by hypoxia. Despite numerous clinical studies with each of these hypoxia-modifying approaches, many of which improved both local tumour control and overall survival, hypoxic modification has not been established in routine clinical practice. Here we review the background and significance of hypoxia, how it can be imaged clinically and focus on the various hypoxia-modifying techniques that have undergone, or are currently in, clinical evaluation.

Drip irrigation with nanobubble oxygenated treated wastewater improves soil aeration

Long-term drip irrigation with treated wastewater (TWW) is known to enhance oxygen deficiency (hypoxia), especially in fine-textured soils. Hypoxia conditions around plant roots negatively affect growth and yield. Experiments were conducted to evaluate the response of lettuce grown in well-aerated (sandy) and poorly aerated (clayey) soils to surface and subsurface drip irrigation with nanobubbles oxygenated TWW (ONB-TWW). Oxygen mass balances show that irrigation with ONB-TWW supplied about 1% of the daily OCO2 emissions. Nevertheless, our results show that both surface and subsurface drip irrigation with ONB-TWW increased the lettuce yield regardless of the soil type or the amount of oxygen added to the soil out of the daily oxygen consumption in it. Irrigation with ONB-TWW significantly reduced membrane leakage and osmotic potential in the roots and leaves in both well-aerated and poorly aerated soils, concomitantly improving root viability and chlorophyll content in the leaves of the plants grown in the poorly aerated clayey soil. The results suggest that drip irrigation with ONB-TWW, should be considered as a viable method to improve oxygen availability in soils and to alleviate soil hypoxia. Further study is needed to elucidate the mechanisms by which ONB promote plant health and growth.

Effects of Highly Oxygenated Water in a Hyperuricemia Rat Model.

Recent years have seen a rapidly rising number of oxygenated water brands that claim to impart health benefits and increase athletic performance by improving oxygen availability in the body. Drinks with higher dissolved oxygen concentrations have in recent times gained popularity as potential ergogenic aids, despite the lack of evidence regarding their efficacy. The aim of this study was to characterize oxygenated water and assess the improvement in uric acid metabolism while identifying performance enhancements in animals administered oxygenated water. Oxygenated water was characterized by hydrogen and oxygen nuclear magnetic resonance (NMR) spectroscopy. Hyperuricemia in rats was induced by treatment with oxonic acid potassium salt, and the animals were given oxygenated drinking water before, during, or after oxonic acid treatment. Serum uric acid was measured to confirm the effects on uric acid metabolism. Following oxygenation, the full width at half maximum (FWHM) was reduced to 11.56 Hz and 64.16 Hz in the hydrogen and oxygen NMR spectra, respectively. Oxygenated water molecule clusters were reduced in size due to the reduction in FWHM. Oxygen concentration did not vary significantly with increased temperature. However, standing time played a critical role in the amount of oxygen dissolved in the water. The rat studies indicated that oxygenated water reduced serum uric acid levels and their rate of increase and enhanced uric acid metabolism. A significant improvement in uric acid metabolism and rate of increase in serum uric acid concentration was observed in hyperuricemic rats administered oxygenated water compared to that in rats administered regular water. High oxygen concentrations enhanced the rate of oxygen absorption, leading to increased glycolysis and mitochondrial protein synthesis. Therefore, oxygenated water is a potential adjuvant therapy or health food for treatment of hyperuricemia.

Electric field promoted oxidation of naphthalene over Cu/Ce0.55Zr0.45Ox catalysts at low temperature

Electric field was applied into the catalytic oxidation for the naphthalene over m% Cu/Ce0.55Zr0.45O2 catalysts. It was found that catalysts with 2% Cu loading exhibit the best catalytic performance and complete naphthalene conversion was achieved at low temperature of 150 °C. The effect of Cu modification and electric field were thoroughly investigated with various characterization technologies. It was found that the doping of Cu to Ce0.55Zr0.45O2 support is beneficial for the oxygen availability and regeneration capability, but suppressive for the naphthalene adsorption. Without electric field, the oxygen availability is the rate determining factor since the oxidation of adsorbed naphthalene on the catalyst surface is the lowest compared with the adsorption and oxygen regeneration process. Under the electric field, the conduction of electricity is through the occupation and reformation of oxygen vacancies by O ion, leading to highly improved oxygen mobility in the catalyst lattice. In addition, the formed Ce3+ in the electric field can easily be re-oxidized by the adjacent CuO, making oxygen species in CuO available for the naphthalene oxidation. Thus the catalytic performance was promoted due to the improved oxygen availability in the electric field and the optimized Cu loading is a balance between the adsorption ability and regeneration capability.

Trajectory of Topsoil Nitrogen Transformations Along a Thermo‐Erosion Gully on the Tibetan Plateau

AbstractPermafrost thaw, especially thermokarst formation, that is, ground collapse due to thawing of ice‐rich permafrost, is expected to alter soil gross nitrogen (N) transformations, which can regulate plant productivity and ecosystem carbon cycle. However, it remains unclear how thermokarst formation modifies soil N processes in permafrost ecosystems. Here 15N pool dilution techniques were used to evaluate changes in topsoil gross N transformations during various thaw stages (early, middle, and late stages) along a thermo‐erosion gully on the Tibetan Plateau. Structural equation modeling was then conducted to explore the relative importance of biotic and abiotic factors in affecting soil gross N transformations. The results showed that topsoil gross N mineralization (GNM) decreased at the three stages, reflecting declined inorganic N production after permafrost collapse. In contrast, topsoil gross nitrification increased only during the early stage. Additionally, the ratio of microbial N immobilization to GNM was enhanced during the middle and late stages, indicating a stronger microbial N limitation after thermokarst formation. The structural equation modeling analysis revealed that soil moisture played an important role in modulating gross N transformations. For GNM, decreased soil moisture had inhibiting effects via regulating the microbial biomass, microbial community, and enzyme activities along the thaw sequence. For gross nitrification, declined soil moisture exerted facilitating effects directly by improving oxygen availability and indirectly by modulating the abundances of ammonia‐oxidizing archaea and bacteria during the early stage. Overall, these results demonstrated that thermokarst formation altered soil N processes, potentially triggering interactions between ecosystem N and carbon cycles after permafrost thaw.

Hyperthermia: The Optimal Treatment to Overcome Radiation Resistant Hypoxia.

Regions of low oxygenation (hypoxia) are a characteristic feature of solid tumors, and cells existing in these regions are a major factor influencing radiation resistance as well as playing a significant role in malignant progression. Consequently, numerous pre-clinical and clinical attempts have been made to try and overcome this hypoxia. These approaches involve improving oxygen availability, radio-sensitizing or killing the hypoxic cells, or utilizing high LET (linear energy transfer) radiation leading to a lower OER (oxygen enhancement ratio). Interestingly, hyperthermia (heat treatments of 39–45 °C) induces many of these effects. Specifically, it increases blood flow thereby improving tissue oxygenation, radio-sensitizes via DNA repair inhibition, and can kill cells either directly or indirectly by causing vascular damage. Combining hyperthermia with low LET radiation can even result in anti-tumor effects equivalent to those seen with high LET. The various mechanisms depend on the time and sequence between radiation and hyperthermia, the heating temperature, and the time of heating. We will discuss the role these factors play in influencing the interaction between hyperthermia and radiation, and summarize the randomized clinical trials showing a benefit of such a combination as well as suggest the potential future clinical application of this combination.

Effects of Lake–Reservoir Pumped-Storage Operations on Temperature and Water Quality

Pumped-storage (PS) hydropower plants are expected to make an important contribution to energy storage in the next decades with growing market shares of new renewable electricity. PS operations affect the water quality of the connected water bodies by exchanging water between them but also by deep water withdrawal from the upper water body. Here, we assess the importance of these two processes in the context of recommissioning a PS hydropower plant by simulating different scenarios with the numerical hydrodynamic and water quality model CE-QUAL-W2. For extended PS operations, the results show significant impacts of the water exchange between the two water bodies on the seasonal dynamics of temperatures, stratification, nutrients, and ice cover, especially in the smaller upper reservoir. Deep water withdrawal was shown to strongly decrease the strength of summer stratification in the upper reservoir, shortening its duration by ~1.5 months, consequently improving oxygen availability, and reducing the accumulation of nutrients in the hypolimnion. These findings highlight the importance of assessing the effects of different options for water withdrawal depths in the design of PS hydropower plants, as well as the relevance of defining a reference state when a PS facility is to be recommissioned.

Computational Study to Identify Feasible Operating Space for a Mixed Mode Combustion Strategy—A Pathway for Premixed Compression Ignition High Load Operation

A mixed mode combustion strategy with a premixed compression ignition (PCI) combustion event and a mixing controlled load extension injection was investigated in the current study. Computational fluid dynamics (CFD) modeling was used to perform a full factorial design of experiments (DOE) to study the effects of premixed fuel fraction, load extension injection timing, and exhaust gas recirculation (EGR). The goal of the study was to identify a feasible operating space and demonstrate a pathway to enable high-load operation with the mixed mode combustion strategy. The gross-indicated efficiency (GIE) increased with premix fraction, but the maximum premix fraction was constrained by pressure rise rate which confined the feasible operating space to a premix fuel mass range of 70–80%. Injecting part of the premixed fuel as a stratified injection relieved the pressure rise rate constraint considerably through in-cylinder equivalence ratio stratification. This allowed operation with premix fuel mass of 70% and higher and EGR rates less than 40% which resulted in improved GIE of the late cycle injection cases. It was also identified that by targeting the fuel from the stratified injection into the squish region, there is improved oxygen availability in the bowl for the load extension injection, which resulted in reduced soot emissions. This allowed the load extension injection to be brought closer to top dead center while meeting the soot constraint, which further improved the GIE. Finally, the results from the study were used to demonstrate high-load operation at 20 bar and 1300 rev/min.

Prior exercise speeds pulmonary oxygen uptake kinetics and increases critical power during supine but not upright cycling.

What is the central question of this study? Critical power (CP) represents the highest work rate for which a metabolic steady state is attainable. The physiological determinants of CP are unclear, but research suggests that CP might be related to the time constant of phaseII oxygen uptake kinetics (τV̇O2). What is the main finding and its importance? We provide the first evidence that τV̇O2 is mechanistically related to CP. A reduction of τV̇O2 in the supine position was observed alongside a concomitant increase in CP. This effect may be contingent on measures of oxygen availability derived from near-infrared spectroscopy. Critical power (CP) is a fundamental parameter defining high-intensity exercise tolerance and is related to the time constant of phaseII pulmonary oxygen uptake kinetics (τV̇O2). To test the hypothesis that this relationship is causal, we determined the impact of prior exercise ('priming') on CP and τV̇O2 in the upright and supine positions. Seventeen healthy men were assigned to either upright or supine exercise groups, whereby CP, τV̇O2 and muscle deoxyhaemoglobin kinetics (τ[HHb] ) were determined via constant-power tests to exhaustion at four work rates with (primed) and without (control) priming exercise at ∼31%Δ. During supine exercise, priming reduced τV̇O2 (control 54±18s versus primed 39±11s; P<0.001), increased τ[HHb] (control 8±4s versus primed 12±4s; P=0.003) and increased CP (control 177±31W versus primed 185±30W, P=0.006) compared with control conditions. However, priming exercise had no effect on τV̇O2 (control 37±12s versus primed 35±8s; P=0.82), τ[HHb] (control 10±5s versus primed 14±10s; P=0.10) or CP (control 235±42W versus primed 232±35W; P=0.57) during upright exercise. The concomitant reduction of τV̇O2 and increased CP following priming in the supine group, effects that were absent in the upright group, provide the first experimental evidence that τV̇O2 is mechanistically related to critical power. The increased τ[HHb+Mb] suggests that this effect was mediated, at least in part, by improved oxygen availability.

The novel combination of theophylline and bambuterol as a potential treatment of hypoxemia in humans.

Hypoxemia can be life-threatening, both acutely and chronically. Because hypoxemia causes vascular dysregulation that further restricts oxygen availability to tissue, it can be pharmacologically addressed. We hypothesized that theophylline can be safely combined with the β2-adrenergic vasodilator bambuterol to improve oxygen availability in hypoxemic patients. Ergogenicity and hemodynamic effects of bambuterol and theophylline were measured in rats under hypobaric and normobaric hypoxia (12% O2). Feasibility in humans was assessed using randomized, double-blind testing of the influence of combined slow-release theophylline (300 mg) and bambuterol (20 mg) on adverse events (AEs), plasma K+, pulse, blood pressure, and drug interaction. Both drugs and their combination significantly improved hypoxic endurance in rats. In humans, common AEs were low K+ (<3.5 mmol/L; bambuterol: 12, theophylline: 4, combination: 13 episodes) and tremors (10, 0, 14 episodes). No exacerbation or serious AE occurred when drugs were combined. A drop in plasma K+ coincided with peak bambuterol plasma concentrations. Bambuterol increased heart rate by approximately 13 bpm. Drug interaction was present but small. We report promise, feasibility, and relative safety of combined theophylline and bambuterol as a treatment of hypoxemia in humans. Cardiac safety and blood K+ will be important safety endpoints when testing these drugs in hypoxemic subjects.

Air\u2013liquid interface enhances oxidative phosphorylation in intestinal epithelial cell line IPEC-J2

The intestinal porcine epithelial cell line IPEC-J2, cultured under the air–liquid interface (ALI) conditions, develops remarkable morphological characteristics close to intestinal epithelial cells in vivo. Improved oxygen availability has been hypothesised to be the leading cause of this morphological differentiation. We assessed oxygen availability in ALI cultures and examined the influence of this cell culture method on glycolysis and oxidative phosphorylation in IPEC-J2 using the submerged membrane culture (SMC) and ALI cultures. Furthermore, the role of HIF-1 as mediator of oxygen availability was analysed. Measurements of oxygen tension confirmed increased oxygen availability at the medium–cell interface and demonstrated reduced oxygen extraction at the basal compartment in ALI. Microarray analysis to determine changes in the genetic profile of IPEC-J2 in ALI identified 2751 modified transcripts. Further examinations of candidate genes revealed reduced levels of glycolytic enzymes hexokinase II and GAPDH, as well as lactate transporting monocarboxylate transporter 1 in ALI, whereas expression of the glucose transporter GLUT1 remained unchanged. Cytochrome c oxidase (COX) subunit 5B protein analysis was increased in ALI, although mRNA level remained at constant level. COX activity was assessed using photometric quantification and a three-fold increase was found in ALI. Quantification of glucose and lactate concentrations in cell culture medium revealed significantly reduced glucose levels and decreased lactate production in ALI. In order to evaluate energy metabolism, we measured cellular adenosine triphosphate (ATP) aggregation in homogenised cell suspensions showing similar levels. However, application of the uncoupling agent FCCP reduced ATP levels in ALI but not in SMC. In addition, HIF showed reduced mRNA levels in ALI. Furthermore, HIF-1α protein was reduced in the nuclear compartment of ALI when compared to SCM as confirmed by confocal microscopy. These results indicate a metabolic switch in IPEC-J2 cultured under ALI conditions enhancing oxidative phosphorylation and suppressing glycolysis. ALI-induced improvement of oxygen supply reduced nuclear HIF-1α, demonstrating a major change in the transcriptional response.

Oxygation of clayey soils by adding hydrogen peroxide to the irrigation solution: Lysimetric experiments

Poorly drained, clayey soils are frequently characterized with oxygen deficiency. One of the methods proposed for improving soil aeration is application of H2O2. The effects of adding hydrogen peroxide to irrigation water on the concentration of oxygen in a clayey soil and on pepper growth parameters were studied in two successive lysimeter (barrel) experiments. This study examined the effects of on-surface and subsurface irrigation with an 800-ppm hydrogen peroxide solution and subsurface irrigation with a 600-ppm hydrogen peroxide solution on oxygen concentrations in a clayey soil and the yield of pepper plants grown in barrels. The main findings were that the use of an 800-ppm H2O2 solution effectively increased the soil–air oxygen concentration, especially when irrigation was applied through on-surface drippers. However, the addition of H2O2 did not increase pepper yield or the rate of stem elongation, possibly due to a dual effect of improved oxygen availability, on the one hand, and physiological damage caused by an oxidative stress (and/or hormonal effect) on the other. Irrigation with a 600-ppm H2O2 solution did not affect the soil–air oxygen concentration; but did slightly decrease the soil volumetric water content and delay the flowering of the pepper plants.

Stimulation of intrarenal endothelin B receptors with Sarafotoxin 6c improves kidney oxygenation in rats with diabetic nephropathy by augmented oxygen availability

Diabetic nephropathy is the leading cause of end stage renal disease. The damage progression has recently been suggested to involve decreased kidney oxygenation as a result of increased oxygen consumption. Furthermore, endothelin A receptors (ETA) are highly related to kidney damage meanwhile endothelin B receptors (ETB) seem to be more protective towards diabetic nephropathy. Therefore, in this study we examined how acute in vivo intrarenal stimulation of ETB affects the progression of kidney damage in rats with diabetic nephropathy.Two weeks post induction of hyperglycemia (Streptozotocin 55 mg/kg) rats werestudied for kidney function and oxygen metabolism during acute in vivo procedures. Parameters were collected during a baseline period with intrarenal saline infusion and during an experimental period with Sarafotoxin 6c (S6c) infusion (0.78125 pmol/h).Hyperglycemic rats had lower kidney oxygenation which increased during S6c infusion. Meanwhile the increased oxygen consumption and glomerular filtration rate was unaffected by the treatment. Renal blood flow, delivered oxygen, urinary sodium excretion and oxidative stress levels increased in both groups during treatment compared to baseline.Conclusively, stimulating ETB with S6c seems to improve the diminished kidney oxygenation in diabetic nephropathy in the same manner as inhibiting ETA, by improving oxygen availability, although not to the same extent.Support or Funding InformationAll experiments were conducted according to FASEB Statement of Principles. This study was supported by the Swedish Research Council, the Swedish Diabetes Foundation and the Swedish Heart Lung Foundation.

Optimizing a woodchip and coal co-firing retrofit for a power utility boiler using CFD

A computational fluid dynamics (CFD) tool, CFX-TASCflow, with a drag force sub-model for woodchip particles was used to explore the optimization of woodchip co-firing of a Canadian utility boiler, after it was first validated by comparing the model results with field operation data when firing Colombia coal. The CFD model predicted both a small increase in NO emissions and a significant increase in unburned carbon in fly ash for the originally proposed co-firing configuration, with 85% of the unburned carbon originating from the woodchips. Improvement strategies were examined, including intensifying the swirl inside the furnace to improve oxygen availability for woodchip combustion, lowering the woodchip injection level to increase residence time, and reducing woodchip particle size to shorten burnout time. The model results revealed the importance of intensified swirl on the burnout of large woodchip particles and the sensitivity of NO emissions to the air distribution in the combustion zone. Also, the model predicted an increase in large unburned woodchip particles falling into the bottom hopper when lowering woodchip injection level, although there was an overall improvement in predicted woodchip burnout. An improvement in woodchip burnout was also observed with reduced woodchip particle size. Based on these results, a co-firing strategy is suggested that is predicted to give reasonable burnout and NOx emissions at a minimum retrofitting cost.

Endothelin type A receptor inhibition normalises intrarenal hypoxia in rats used as a model of type 1 diabetes by improving oxygen delivery.

Intrarenal tissue hypoxia, secondary to increased oxygen consumption, has been suggested as a unifying mechanism for the development of diabetic nephropathy. Increased endothelin-1 signalling via the endothelin type A receptor (ETA-R) has been shown to contribute to the development of chronic kidney disease, but its role in kidney oxygen homeostasis is presently unknown. The effects of acute ETA-R inhibition (8 nmol/l BQ-123 for 30-40 min directly into the left renal artery) on kidney function and oxygen metabolism were investigated in normoglycaemic control and insulinopenic male Sprague Dawley rats (55 mg/kg streptozotocin intravenously 2 weeks before the main experiment) used as a model of type 1 diabetes. Local inhibition of ETA-R in the left kidney did not affect BP in either the control or the diabetic rats. As previously reported, diabetic rats displayed increased kidney oxygen consumption resulting in tissue hypoxia in both the kidney cortex and medulla. The inhibition of ETA-Rs restored normal kidney tissue oxygen availability in the diabetic kidney by increasing renal blood flow, but did not affect oxygen consumption. Furthermore, ETA-R inhibition reduced the diabetes-induced glomerular hyperfiltration and increased the urinary sodium excretion. Kidney function in normoglycaemic control rats was largely unaffected by BQ-123 treatment, although it also increased renal blood flow and urinary sodium excretion in these animals. Acutely reduced intrarenal ETA-R signalling results in significantly improved oxygen availability in the diabetic kidney secondary to elevated renal perfusion. Thus, the beneficial effects of ETA-R inhibition on kidney function in diabetes may be due to improved intrarenal oxygen homeostasis.