Increasing Oxygen Content Research Articles

Increased oxygen content in biochar lowered bioavailability of polycyclic aromatic hydrocarbons–related toxicity to various organisms

Agricultural or environmental application of biochar (BC) is connected with the introduction of biochar-derived components among which polycyclic aromatic hydrocarbons (PAHs) and heavy metals are the most toxic. Their presence and bioavailability are crucial considering biochar toxicity. The effect of feedstock and pyrolysis temperature on the physicochemical properties of produced biochar and contaminant content was established and combined with toxicity to a broad range of living organisms. The obtained data revealed that predicting the bioavailability of PAHs using the total content is misleading. The toxicity was influenced by factors in the following way: the bioavailable PAHs > ash > total PAHs content in BC stressing the role of BC physicochemical characteristics. Among tested BC properties, surface functionalization, e.g. presence of oxygen-containing functional groups was crucial in revealing the toxicity. The data clearly indicate that additional research is required to determine BC’s impact on various organisms and performing one ecotoxicity test is not sufficient.

Marine redox and nutrient dynamics linked to the Cambrian radiation of animals

Abstract The early Cambrian witnessed an increase in metazoan ecosystem complexity, likely linked to enhanced oxygen and nutrient availability. However, while improved stratigraphic and geochemical records suggest that the Cambrian explosion occurred under highly dynamic redox conditions, mechanistic links to nutrient availability and early Cambrian evolutionary innovations are poorly constrained. Here, we report paleoredox and nutrient data for two drill cores documenting late Cambrian Stage 2 to Stage 3 (ca. 522–514 Ma) strata from the Yangtze block, South China. The development of water-column euxinia during Cambrian Stage 2 led to extensive recycling of P, fueling elevated primary production and hence an increase in atmospheric and shallow-marine oxygen concentrations. The resulting expansion of oxygenated shelf area promoted sedimentary P retention and, in combination with a diminished supply of P from upwelling, drove a transition to oligotrophic shallow-marine conditions during Cambrian Stage 3. Reduced primary production and limited water-column oxygen consumption allowed for the stabilization of oxygenated continental shelf habitats that supported a burgeoning biotic complexity.

Temperatures and hypolimnetic oxygen in German lakes: Observations, future trends and adaptation potential.

We investigated trends in temperature, stratification, and hypolimnetic oxygen concentration of German lakes under climate change using observational data and hydrodynamic modelling. Observations from 46 lakes revealed that annually averaged surface temperatures increased by + 0.5°C between 1990 and 2020 while bottom temperatures remained almost constant. Modelling of 12 lakes predicted further increases in surface temperatures by 0.3°C/decade until the year 2099 in the most pessimistic emission scenario RCP 8.5 (RCP 4.5: + 0.18°C/decade; RCP 2.6: + 0.04°C/decade). Again, bottom temperatures increased much less while summer stratification extended by up to 38days. Using a simplified oxygen model, we showed that hypolimnetic oxygen concentrations decreased by 0.7-1.9mgL-1 in response to the extended stratification period. However, model runs assuming lower productivity (e. g. through nutrient reduction) resulted in increased oxygen concentrations even in the most pessimistic emission scenario. Our results suggest that the negative effects of climate change on the oxygen budget of lakes can be efficiently mitigated by nutrient control.

Oxygen concentration – A governing parameter for microstructural tailoring of duplex AlCrSiON coatings for superior mechanical, tribological, and anti-corrosion performance

This study investigates the impact of increasing oxygen levels on structure, and mechanical properties and tribological performance of duplex AlCrSiON coatings. AISI H13 steel and tungsten carbide substrates are coated using arc ion plating with increasing oxygen flow rate up to 200 sccm with varying oxygen concentration. High-resolution transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and three-dimensional profilometer are used to study morphological and structural evolution. Correspondingly, the coatings are assessed for hardness, adhesion strength, friction coefficient, and resistance against corrosion and wear. A 50–100 sccm oxygen flow rate is considered as an optimal range to receive lower surface roughness. Generally, the addition of oxygen has compromised hardness and friction coefficient but improve adhesion strength, wear and corrosion resistance with increasing oxygen concentration. The immersion tests have identified pitting corrosion as a dominating failure mechanism for AlCrSiON coatings when exposed to molten A380 aluminium alloy. This corrosion resistance stems from their dense microstructure, excellent thermal stability, and the presence of fcc-(Al, Cr)2O3 phase structure. This study demonstrates that controlled oxygen concentration is a crucial parameter for tuning the microstructure of AlCrSiON coatings to achieve superior mechanical, tribological, and anti-corrosion performance, particularly for high-pressure die-casting applications.

Analysis of nitrogen adsorption capability at various activation temperatures of Klaten natural zeolite

The Pressure Swing Adsorption (PSA) method operates by passing air through an adsorbent to produce concentrated oxygen gas. Zeolites are commonly utilized as adsorbents due to their ability to adsorb nitrogen from the surrounding air. Two types of zeolites commonly employed are natural and synthetic zeolites. While the utilization of natural zeolites as adsorbents in oxygen purification remains limited, their potential as an alternative adsorbent is worth exploring in this field. This study focused on developing physically activated Klaten natural zeolite as an adsorbent to enhance oxygen purity. Physical activation involved heating for 1.5 hours using an electric oven at four temperature variations (250ºC, 300ºC, 350ºC, and 400ºC). Additionally, four distinct flow rates were tested: 0.1; 0.5; 1.0; and 1.5 lpm. Oxygen purification testing revealed that higher activation temperatures led to greater increases in oxygen concentration. The highest increase of 2.45% was achieved at an activation temperature of 400ºC, while the lowest increase of 1.75% was observed at 250ºC with a flow rate of 0.1 lpm. With a 10-minute holding period, oxygen content during the adsorption process ranged from 1.35% to 2.45%, compared to 0.60%-0.75% without holding. Physical activation of zeolite from Klaten enhanced its nitrogen absorption capacity, indicating the potential of natural zeolite from Klaten for oxygen purification through optimized activation processes, possibly via chemical activation

Effect of oxygen on the microstructure, tensile properties and deformation behaviours of a biocompatible Ti40Zr25Nb25Ta10 high entropy alloy

The effect of oxygen on the microstructure, mechanical properties and deformation behaviours of as-cast biocompatible Ti40Zr25Nb25Ta10Ox (x = 0.5, 1.0 and 2.0 at.%) high entropy alloys (HEAs) was investigated. All three oxygen-doped HEAs solidified as a single body-centred cubic (BCC) phase grain structure with predominantly high-angle grain boundaries following the Mackenzie prediction. Increasing oxygen content significantly increased tensile strength at a rate of about 180 MPa/1.0 at.%, but decreased tensile ductility. However, at the addition level of 0.5 at.% O, the as-cast Ti40Zr25Nb25Ta10O0.5 HEA can achieve a yield strength (σ0.2) of 947 ± 44 MPa and an elongation at break (εf) of 9.5 % ± 1.8 %. These properties make this HEA comparable to medical grade Ti-6Al-4V (wt.%) alloy (ASTM Grade 23 titanium) (σ0.2 ≥ 759 MPa; εf ≥ 10 %) in its ability to absorb energy in plastic deformation, while offering greater resistance to permanent shape changes. Due to the possible strong interaction between oxygen atoms and dislocations through pinning and de-pinning, all oxygen-doped HEAs exhibited discontinuous yielding, whereas the low oxygen base HEA underwent normal yielding. No oxygen clusters were detected through atom probe tomography (APT) analysis. The deformation mechanism depends on oxygen content. The plastic deformation of the Ti40Zr25Nb25Ta10O0.5 HEA occurred through the formation of primary and secondary shear bands. In contrast, planar slip bands and a limited number of primary shear bands (without secondary shear bands) were observed in the Ti40Zr25Nb25Ta10O2.0 HEA. To ensure sufficient ductility, the oxygen content should be limited to 0.5 at.%. Furthermore, at this oxygen content, the corrosion resistance of the Ti40Zr25Nb25Ta10O0.5 HEA in Hank's solution is comparable to that of Ti-6Al-4V.

Experimental and numerical investigations of soot formation in propane laminar coflow flames in O2/N2 and O2/CO2 atmospheres

Oxygen-rich combustion is a new type of clean combustion technology with important application prospects. At present, there are few detailed analyses on the mechanism changes of soot formation under oxygen enrichment of propane. In this paper, the effects of oxygen-rich (O2/N2, O2/CO2) combustion on soot formation in the propane laminar flow coaxial jet diffusion flame were investigated by using the experiment and numerical simulation. The flame image was taken by a color (CCD) camera in the visible band, and the two-dimensional distribution of temperature and soot volume fraction in the flame was reconstructed. In numerical simulation, the soot production model considers a detailed description of nucleation via collisions among heavy polycyclic aromatic hydrocarbons, particle aggregation, polycyclic aromatic hydrocarbons condensation, surface growth and oxidation through the hydrogen abstraction acetylene addition mechanism. The results show that the experimental results were compared with the numerical simulation results, and the numerical simulation results predict the temperature and soot change of oxygen-rich flame well. With the increase in oxygen concentration, the peaks of soot and temperature in the two oxygen-rich atmospheres gradually increased. With the increase in oxygen concentration, the peaks of soot and temperature in the two oxygen-rich atmospheres gradually increased. Comparing the combustion mechanism changes of the two oxygen-rich combustion systems, it was found that the hydrogen abstraction acetylene addition mechanism was the main cause of soot generation. The OH oxidation is dominated near the fuel nozzle side, and O2 oxidation is dominant downstream. With the substitution of CO2 for N2, the chemical effect of CO2 reduces the flame temperature and inhibits the formation mechanism and oxidation mechanism of soot to some extent. This in turn leaded to a reduction in the amount of soot produced.

Research on shock wave driving technology of methane explosion

In order to improve the driving ability of the explosion wave simulation equipment, reduce the erosion effect of condensed explosives on the explosion wave simulation equipment, improve the safety of the test process, and make better use of the meteorological detonation driving method, it is necessary to optimize the source of the shock wave load in the driving section. Based on the finite volume method of FLACS, a methane detonation driving model corresponding to the test is established to explore the feasibility of using methane as an explosion source to test the structure against explosion shock wave. A methane detonation drive test was carried out to verify the accuracy of the numerical model. Finally, an engineering model for attenuation of shock wave overpressure peak value in pipeline is established by dimensional analysis, and the model coefficient is determined by numerical simulation and test data. The results show that the blast pressure is the highest when the methane volume ratio reaches 9.5 vol% in the methane-air mixture. Simply increasing oxygen content has little effect on the peak overpressure and positive pressure duration of shock wave. In the pure oxygen environment, the detonation effect can be achieved when the volume ratio of methane to oxygen is 1:2, and the incident pressure of the shock wave is proportional to the volume of the gas cloud. When the gas cloud volume is constant, a reasonable selection of methane-oxygen mixture ratio can achieve a better detonation effect, which can effectively increase the peak overpressure of the shock wave in the test section. The research results can provide technical reference for the development of new explosion wave simulation equipment.

System simulation and parametric analysis of low-concentration coal mine gas fed SOFC-CHP with deoxygenation and enrichment pretreatment

Solid oxide fuel cell (SOFC) combined heat and power (CHP) can efficiently convert low-concentration coal mine gas (LC-CMG) into clean energy, avoiding the greenhouse effect of LC-CMG. Deoxygenation and methane enrichment pretreatment of LC-CMG can prevent explosion and anode oxidation risk. Herein, a chemical process model of LC-CMG fed SOFC-CHP system with the pretreatment was established to predict the performances under different operating conditions. Performance evaluation and exergy analysis were performed considering the use of oxygen-rich gas from the pretreatment at SOFC cathode. The effects of key operation parameters on system performances were investigated in terms of residual oxygen concentration, inlet methane concentration, fuel flow and fuel utilization. The results indicated that net electrical efficiency and heat supply efficiency can respectively reach 49.13 % and 23.90 % using LC-CMG of 15 % CH4 with enhancing effect of oxygen-rich gas at cathode. The decrease of methane concentration and the increase of residual oxygen concentration and flow rate caused the decreased electrical efficiency but the increased heat supply efficiency due to the enlargement of concentration polarization and heat supply. The optimal operation parameters were recognized by comprehensively considering diverse performance indicators. This work can guide system integration and operation optimization of LC-CMG fed SOFC-CHP.

Effect of ZnO nanoparticle on combustion and emission characteristics of a diesel engine powered by lemongrass biodiesel: an experimental approach

Biodiesel (BD) is one of the efficient alternative fuels for diesel engines (DE) which can be employed sans any modifications. The present study is focused on the extraction of BD from a lemongrass plant and analyzing combustion, efficiency, and emission characteristics of the DE by adding NPs at different concentrations to reduce both hydrocarbon, carbon monoxide, and NOx emissions simultaneously from the DE. The fuel samples were prepared by adding different dosages of zinc oxide nanoparticles (ZnO NPs) with neat lemongrass biodiesel (LGB) such as 50 ppm, 100 ppm, 150 ppm, 200 ppm, and 250 ppm per liter. From the results, it is found that the properties of BD were improved by the addition of ZnO NPs and it increased oxygen concentration in the sample resulting in better combustion and lower exhaust pollutants. The DE tested with the LGB + 150 ppm sample has registered maximum brake thermal efficiency (BTE) and lower specific fuel combustion (SFC) for all loading conditions compared to other samples. The value of heat release rate (HRR) and in-cylinder pressure are higher for LGB + 150 ppm due to its specific properties compared to other LGB blends. The presence of ZnO NPs in LGB has reduced harmful emissions from the DE such as carbon monoxide (CO), hydrocarbon (HC), oxides of nitrogen (NOx), and smoke by 4.01%, 5.56%, and 19.01%, when compared to neat LGB.

Accelerated oxidation of epoxy thermosets with increased O2 pressure

Polymer oxidation is usually accelerated with temperature, which is therefore applied in nearly every experimental approach dealing with predictive materials aging. Because of this simple approach, we may tend to neglect that the effective concentration of oxygen also acts as a rate multiplier for oxidation. Increasing the oxygen partial pressure in an aging environment accelerates oxidation, and while there is often a near proportional increase initially, the effect of additional oxygen usually transitions to a saturation level at some elevated pressure. This has been theoretically described in the general autoxidation scheme and is well recognized. However, for many materials the exact rate behavior under moderately increased oxygen concentration remains to be established. We therefore review epoxy oxidation and offer a broader overview of its behavior under increased O2 partial pressure. Experimental data are given for a few thermoset materials demonstrating their rate behavior under O2 partial pressure up to 4 atm, meaning approximately 20 times more than under standard atmospheric conditions. Confirmative evidence suggests that epoxy materials will reach saturation oxidation rates only at significantly higher O2 partial pressure. In such a high-pressure regime it is theoretically possible to not only accelerate oxidation, but to transition into a condition where O2 diffusion can be increased without further accelerating the oxidation rate. This can reduce diffusion limited oxidation effects under specific accelerated aging conditions as a combination of temperature and O2 partial pressure.

Daily and other short-term changes in the ecosystem components of the world's largest hypersaline lagoon Bay Sivash (Crimea)

The interrelationship between various processes and components in the daily cycle of water bodies has been little studied, especially in hypersaline water bodies. A three-day study was conducted in the world's largest hypersaline lagoon Bay Sivash (the Sea of Azov). 16 biotic and abiotic parameters were measured 21–80 times in the studied site (wind direction and speed, photosynthetically active radiation (PAR), temperature, oxygen content, pH, Eh, turbidity, chlorophyll a fluorescence, zooplankton abundance, and others). There was a clear daily rhythm of PAR in the surface layer of the water, however, the stochastic weather factor (cloudiness, wind speed and direction) influenced the quantitative expression of it. The proportion of PAR entering deeper layers as shown, depends on the height of the Sun, as well as intra-ecosystem factors, for example turbidity and the development of mats of filamentous algae. Fluctuating from 1.69 to 98.03 NTU, turbidity depended on the speed and direction of the wind with windward winds leading to the resuspension of bottom sediments to a greater extent than leeward ones. Wind speed and direction also significantly influenced the distribution of biotic components such as the filamentous green alga Cladophora and zooplankton. Oxygen content fluctuated from between 1.8 and 16.58 mg L−1. An increase in oxygen concentration was observed only at PAR above approximately 500–1000 μE m−2;s−1. The increase in temperature and the virtual absence of wind, which was observed on 05/28/2022 and 05/29/2022, contributed to an increase in the oxygen concentration in the water on these days and the formation of hyperoxic conditions in this hypersaline lagoon.

Effect of oxy-fuel combustion with different O2/CO2 fractions on the pulverized coal combustion mechanism and heat transfer characteristics in rotary kilns: A numerical simulation study

Oxy-fuel combustion combined with carbon capture and storage is the most effective and direct technology to achieve carbon neutrality in cement industry. In this work, numerical simulation was employed to investigate the effects of air combustion and oxy-fuel combustion with different O2/CO2 fractions on the airflow field, temperature field, pulverized coal combustion mechanism, heat transfer characteristics and NOx distribution in rotary kiln. The results show that the airflow field under different conditions has no significant change. When transitioning from the air condition to the oxy-fuel condition, the ignition point of pulverized coal extends backward by approximately 0.2 m. The maximum temperature decreases from 2306 K to 2052 K, and the temperature becomes more uniform. As the oxygen concentration in the primary air increases, both the maximum and average temperatures gradually rise, and the flame length shortens from 25.4 m to 24.16 m. In the rotary kiln, the locations of char oxidation and gasification reactions differ, but these reaction locations remain consistent under different conditions. Under oxy-fuel conditions, the oxidation rate and oxidation proportion of char decrease, while the gasification rate and gasification proportion of char increase, resulting in a shortening of the burnout distance of coal from 34.5 m to 31.3 m. With increasing oxygen concentration in the primary air, the rates of char oxidation and gasification gradually rise, further shortening the burnout distance. The decrease in temperature at the front end of the rotary kiln under oxy-fuel conditions reduces the total heat transfer in the burning zone by 15 %. When the oxygen content of the primary air is 70 %, it ensures stable calcination of clinker. Additionally, under oxy-fuel conditions, the NOx generation is significantly reduced. With the increase of oxygen concentration in the primary air, the NOx concentration at the outlet decreases slightly from 451 ppm to 406 ppm, due to the increase in kiln temperature that favors the reduction of fuel NOx.

Analysis of stage parameters of low-temperature oxidation of water-soaked coal based on kinetic principles

Mine fires caused by spontaneous coal combustion are major disasters in coal mines. The staged oxidation kinetic parameters of various coal samples at oxygen concentrations of 21 %, 15 %, 10 %, 5 %, and 3 % were analyzed using a programmed temperature testing system. Herein, the temperature increase rate of coal, the temperature difference between the furnace and coal, and the oxygen consumption characteristics were obtained. Based on the amount of CO produced and the temperature sensitivity coefficient, three characteristic temperatures and four stages of low-temperature oxidation (LTO) were identified. The results showed that at a critical temperature (TC), the amount of CO gas released from the coal samples increased with increasing oxygen concentration, and the difference in the oxygen consumption rate increased. After the limit temperature (Tu), the amount of CO gas increased steadily, and the increase in the oxygen consumption rate stagnated. CO production, the maximum heating rate, and the maximum heat release rate were positively correlated with the oxygen concentration. As the oxygen concentration increased, the activation energy during the oxygen absorption stage gradually decreased. The average reaction enthalpy (ΔH) of pre-oxidized water-immersed coal was 19.37 kJ/kg greater than that of raw coal. The equation for the conservation of energy of the coal oxidation warming process was normalized. The theoretical values of the awakening stage and the stable stage were τν and τν (1-B), respectively. When B was >1, pre-oxidized water-immersed coal at a low oxygen concentration was prone to crossover points during the oxygen absorption stage, which increased the risk of coal spontaneous combustion (CSC). The research results could provide a theoretical basis for the staged control of the spontaneous combustion of water-immersed coal in goaf areas.

Influence of O2 on structural evolution of biochar in oxidative pyrolysis of cellulose

Oxidative pyrolysis could mitigate energy requirement in endothermic pyrolysis, but evolution of pyrolytic products might be impacted in oxidative atomosphere. This was investigated herein at 300–600 °C in a carrier gas of 11 vol% of oxygen with cellulose as a research object for the pyrolysis, as cellulose-derived aliphatic structures are prone to oxidization. The results indicated that O2 reacted with organics on cellulose/biochar even from 300 °C, decreasing biochar production while enhancing bio-oil formation. Oxidation of the organics on the biochar increased CO/CC ratio but did not increase oxygen content, as formation of the oxygen-containing aliphatic structures and their elimination via cracking took place in parallel, which in overall formed the biochar of higher C/O and C/H ratios, but not necessarily higher thermal stability. The abundance of the thermally unstable aliphatic structures was responsible for this, but it was also the reason for the improved comprehensive combustion characteristic index and combustion kinetics. Additionally, pyrolysis at 600 °C in presence of O2 formed the biochar with a specific surface area of 426.2 m2/g (mainly micropores), which was significantly higher than that of counterpart in nitrogen (28.9 m2/g). The in-situ IR characterization of the pyrolysis suggested that O2 favored formation of oxygen-containing species such as -OH, CO of varied forms, *CO2, olefinic CC but not aromatic CC.

Geochemical impact of biomethane and natural gas blend injection in deep aquifer storage

Biomethane is one of the main renewable gases available today to offset fossil gas and decarbonize the energy system. The EU is seeking to rapidly replace part of the natural gas usually stored in deep saline aquifers by biomethane which contains up to 10000 ppm of O2. This study presents for the first-time assessment of deep aquifers’ resilience to biomethane and natural gas blend injection into two sandstone reservoirs with different mineral paragenesis from the Paris Basin (France). Multiphase reactive transport modeling allowed to evaluate changes in gas and water quality, mineralogy and moreover, to identify major resilience properties of storage facilities necessary to buffer the oxygen reactivity and induced acidification coming from gas–water–rock interactions. In the presence of pyrite, the injected oxygen is consumed during pyrite oxidation and contributes to the acidification of the formation water close to the injection point. However, the injection of 1% mole fraction of CO2(g) contained in the gas blend is found to be the main acidification factor. The analysis of reservoir resilience showed three protection levels of pH buffering capacity, which can effectively mitigate an increase in oxygen content up to 1000 ppm: (i) calcite dissolution, (ii) plagioclase and clay dissolution and (iii) clay sorption capacity. Models predict that the gas blend injection could induce minimal but long-term change in the mineralogy without significantly impacting the global porosity. Overall, both sandstones can preserve the quality of the gas plume despite partial CO2(g) exsolution induced by the geochemical perturbation of the formations. The developed models will be used as a basis for assessment of renewable natural gas storage facilities in the long-term.

An attachment oxygen supply method for improving the sleep space environment in the Tibetan Plateau

The hypoxic environment results in common sleep problems for the local inhabitants of the Tibetan Plateau. Based on attachment ventilation, this study proposed an attachment oxygen supply device (AOSD) to improve the sleep space environment. The field tests were conducted in Lhasa to verify the oxygen supply effect of the AOSD and compared it with the traditional diffusive oxygen supply device (T-DOSD). The field tests were divided into two segments: the test of environmental parameters within the bedroom and the physiological parameters of the subjects. The results showed that the AOSD could create a comfortable oxygen-enriched environment for sleep space. At an oxygen flow of 10 L/min, compared to the initial oxygen concentration in the breathing zone, the oxygen concentration in the breathing zone is increased to 26.1% with the AOSD and 22.0% with the T-DOSD. When the oxygen flow is the same at 10 L/min, the AOSD increases oxygen concentration in the breathing zone by 4.1% compared to utilizing the T-DOSD. In addition, there was a decrease in heart rate and an increase in arterial oxygen saturation of subjects utilizing the AOSD. Therefore, the AOSD oxygen supply effect was further verified. The research contributes to improving both the sleep space environment and the sleep quality for inhabitants in an effective and energy-saving approach.

Redox Properties of Mn(III)porphyrins in Hyaluronan Oxidative Degradation: Single Electron Transfer Mechanism.

Cationic Mn(III)-meso-tetraarylporphyrin derivatives, substituted in para position with different size alkyl chains, were investigated to function as antioxidants in free-radical degradation of high-molar-mass hyaluronan by the methods of rotational viscometry and oximetry. The results of rotational viscometry showed that MnTM-4-PyP5+, MnTE-4-PyP5+, MnTPr-4-PyP5+, MnTPen-4-PyP5+ and MnTHep-4-PyP5+ showed high efficiency in decomposing H2O2, and reducing of peroxidized hyaluronan. When using oxygen electrode, MnTE-4-PyP5+, MnTPr-4-PyP5+, MnTPen-4-PyP5+, and MnTHep-4-PyP5+ applied to function as protective antioxidants in hyaluronan degradation, the uptake of dissolved oxygen from the reaction milieu was rapid, followed by continual increase in oxygen concentration up to the end of the measurement. However, when especially MnTE-4-PyP5+, MnTPr-4-PyP5+, and MnTPen-4-PyP5+ were examined as hyaluronan chain-breaking antioxidants, after short-term dissolved oxygen uptake, almost no increase in oxygen concentration was shown.

Measuring flow rate and purity in portable oxygen concentrators

For people with respiratory disorders who need additional oxygen therapy, oxygen concentrators are vital medical equipment. By concentrating oxygen from the ambient air, they function to give the user a greater flow of oxygen-enriched air. The application of lithium zeolite for oxygen concentration in POCs is the most intense part of this work. One kind of zeolite material that may selectively absorb nitrogen from the air to increase oxygen concentration is lithium zeolite. The capacity, effectiveness, and dependability of a POC fitted with lithium zeolite are all examined in this study, along with its overall performance. The findings show that lithium zeolite, which has benefits including high oxygen purity and low energy consumption, is a potential material for use in POCs. The results of this study aid in the creation of POCs for oxygen therapy that are more effective and efficient. This study suggests utilizing an Arduino microcontroller and an HX710B air pressure sensor to measure the oxygen flow rate in a POC. The POC’s oxygen flow channel incorporates the HX710B sensor to monitor pressure variations, which the Arduino uses to translate into flow rate readings. To verify the accuracy and dependability of the system, its performance is assessed under different flow rate scenarios. Lithium zeolites are well-known for having a high selectivity for nitrogen adsorption, which can enhance the concentrator’s oxygen separation process’s effectiveness. Lithium-zeolite-based oxygen concentrators may have a lower environmental effect than standard concentrators.

Electrochemical Study and Mechanical Properties of Ti-Zr Alloy for Biomedical Applications

In response to concerns of potential cytotoxicity and adverse tissue reactions caused by vanadium and aluminum in the currently used biomaterial Ti-6Al-4V, the Ti–20Zr alloy was evaluated in this study because it has been suggested as a candidate for human body implant material. The Ti-20Zr alloy was obtained by vacuum-melting, followed by heat treatment at 1000 °C for 1 h, and then air-cooled. Optical and scanning electron microscopy revealed that the sample had an α and β lamellar microstructure. Analysis showed that the mechanical properties, in terms of hardness measurements performed at low loads, were significantly different between the two phases. Thus, it was found out that the α phase is softer by about 30% compared to the β phase. The Electrochemical Impedance Spectroscopy technique (EIS) was employed to study the electrochemical behavior in simulated body fluid (SBF). The electrochemical behavior demonstrated that Ti-20Zr alloy exhibits excellent corrosion resistance due to the stable oxide layer formed on its surface. SEM and EDS investigations showed that the surface topography, after electrochemical studies, is characterized by a porous film with increased oxygen content, which might be suitable for the osteoinductive growth of bone.