Decrease In Oxygen Concentration Research Articles

Naturally changing reference conditions: Evidence of isostatic uplift being the main cause of changes in ecological status in a SW Norwegian fjord system

According to the European Water Framework Directive (WFD), restoration actions are needed if the present-day ecological quality status (EcoQS) is worse than good. However, less stringent environmental objectives may be allowed if the water body’s natural condition is such that it may be unfeasible or unreasonably expensive to achieve good conditions.In the Inner Skjolda- and Grindefjord, an isolated and shallow silled fjordsystem on the SW coast of Norway, the present EcoQS (based on benthic foraminifera and macroinvertebrates) is bad due to anoxic conditions in the bottom water. Paleoecological foraminiferal data in two dated sediment records were used to establish in situ reference conditions. The data revealed that the current bad EcoQS did not deviate from the natural reference condition which existed just prior to the onset of the industrial revolution. Further back in time, the record showed poor EcoQS and a strong dominance of the opportunistic foraminiferal species Stainforthia fusiformis, indicating unfavorable conditions for benthic foraminifera already >2000 years ago. The changing ecological status during the pre-industrial period was probably caused by the inner fjordsystem becoming gradually more isolated and stratified, and the bottom water more stagnant with decreasing oxygen concentrations, in response to isostatic uplift. Our study shows that reference conditions at a location may represent a natural succession of environmental changes i.e., the natural baseline does not have to represent only one environmental condition but may vary naturally over time. We therefore suggest that the conditions just prior to the onset of the industrial revolution should be used when defining reference conditions according to the WFD.

Evaluation of the effect of high air temperature on the behavioural activity and physical performance of animals (in a rat model)

Introduction. The profession of firefighters belongs to extreme activities. Fire hazards include flames, sparks, heat flow, elevated ambient temperatures, increased concentrations of toxic combustion and thermal decomposition products, decreased oxygen concentrations, and reduced visibility in smoke. High air temperature during fire extinguishing is one of the main adverse physical factors affecting firefighters’ bodies. Material and methods. The study was carried out on 124 outbred white male 3-month rats weighing 250-300 g, divided randomly into two groups: the first group (62 rats) underwent single hyperthermia. The second group (62 rats) experienced daily hyperthermia for 14 days. The study of the behavioural activity of animals was carried out after single and prolonged hyperthermia using the following methods: “Open field”, “Elevated cruciform maze”, Porsolt’s test, running on a treadmill. The tests were performed two times: the first time - before exposure, the second - after, with intervals between tests of at least two weeks. Results. The data obtained indicate that the high ambient temperature causes changes in the behavioural responses in animals, which is expressed by an increase in the level of anxiety, a decrease in motor and research activity, the development of depressive states, and a decrease in physical endurance. Conclusion. An experimental model of extreme heat exposure on animals showed the emergence and persistence of changes in animals’ behavioural activity and physical performance indicators. This experiment can be used to study the long-term effects of high temperatures on firefighters’ bodies.

The Art of Inducing Hypoxia

Many cells in the human body strongly react on decreased oxygen concentrations, generally defined as hypoxia. Therefore, inducing hypoxia in vitro is essential for research. Classically, hypoxia is induced using a hypoxia chamber, but alternative methods exist that do not require special equipment. Here, we compared three different methods to induce hypoxia without a hypoxia chamber: the chemical stabilization of HIF-1α by CoCl2, the decrease in pericellular oxygen concentrations by increased media height, and the consumption of oxygen by an enzymatic system. Hypoxia induction was further analyzed within three different cell culture systems: 2D (adherent) osteoprogenitor cells, monocytic (suspension) cells, and in a 3D in vitro fracture hematoma model. The different methods were analyzed within the scope of fracture healing regarding inflammation and differentiation. We could show that all three induction methods were feasible for hypoxia induction within adherent cells. Increased media heights did not stimulate a hypoxic response within suspension cells and in the 3D system. Chemical stabilization of HIF-1α showed limitations when looking at the expression of cytokines in osteoprogenitors and monocytes. Enzymatic reduction of oxygen proofed to be most effective within all three systems inducing inflammation and differentiation.

Study of the relationship among total oxygen, inclusions and fatigue properties of gear steel

In order to control non-metallic inclusions and improve fatigue performance of gear steel, the relationship among total oxygen, inclusion size and fatigue properties of gear steel was investigated. In the work, Mn–Cr system gear steels with different total oxygen contents were selected as the research objects. Inclusions and fatigue properties of gear steels with different total oxygen contents were studied by using traditional metallographic method, extreme value method and fatigue test. The experimental results demonstrates that with the decrease of total oxygen content（i.e., 0.0013%→0.0010%→0.0005%）, the number of small-size oxide inclusions in the range of 5–10 μm decreases greatly, whereas the number of large-size oxide inclusions over 10 μm has relatively little change. Meanwhile, it is found that the change of total oxygen content in different ranges has different influences on the size of maximum size oxide inclusion and fatigue properties. Reducing the total oxygen content of gear steel from 0.0013% to 0.0010% decreases the inclusion size of maximum oxide inclusion and improves fatigue resistance of materials, but these benefits do not extend to a total oxygen level of 0.0005%. Accordingly, we can conclude that no evident linear correlation exists between total oxygen content and maximum inclusion size or between the total oxygen content and the fatigue performance.

Catalytic co-pyrolysis of woody biomass with waste plastics: Effects of HZSM-5 and pyrolysis temperature on producing high-value pyrolytic products and reducing wax formation

In this study, using an analytical pyrolysis-GC/MS system, pine sawdust was pyrolyzed with polyethylene (PE) and polyethylene terephthalate (PET) in the presence of HZSM-5 to investigate the effect of plastic. Pyrolysis was performed at 500 °C, 600 °C, and 700 °C after 3.0 mg feedstock loading. Chemical compounds were identified and classified into six groups: Monomeric Aromatic Hydrocarbon (MAH), Polycyclic Aromatic Hydrocarbon (PAH), Phenols, Furfurals, Alkenes, and Alkanes. Results showed that pine and PE co-pyrolysis significantly decreased oxygen content from 23.4% (pine only) to 0.3% (pine + PE/HZSM-5), which increased products’ HHV from 25.9 MJ/kg to 34.4 MJ/kg. It also revealed that the pine and PE ratio did not heavily influence the petrochemical concentration (aromatic hydrocarbons + alkenes (C ≤ 15) + alkanes (C ≤ 13)). However, a higher plastic ratio led to a higher wax production, which is the reason for poor condensation performance in condenser bio-oil capture. A pinewood sawdust to PE ratio of 3:1 showed the most higher-level petrochemicals and least amount of wax formation. Pine and PET co-pyrolysis produced significantly less wax and similar aromatic hydrocarbons to pine and PE co-pyrolysis. It also made as many acids as PET depolymerization and is a problem for pyrolysis oil use.

Vibration influence on the O2-dependent processes activity in human erythrocytes

The early signs of vibration effects on the human body are microcirculation and transcapillary metabolism disorders, accompanied by disruption of the supply to and utilization of oxygen in the tissues and organs. However, there are few experimental studies aimed at finding targets of vibration in cells and determining the action mechanism of vibration. In in vitro experiments, human erythrocytes in buffer solution were exposed to low-frequency vibration (frequency range 8–32 Hz, amplitudes 0.5–0.9 mm) for 3 hours. The dynamics of the accumulation of membrane-bound catalase and hemoglobin and the distribution of ligand hemoglobin in the membrane-bound fraction were studied as the indicators of functional activity of cells. The choice of these indicators is justified by the participation of catalase and hemoglobin in O2-dependent cellular reactions as a part of protein complexes. Since pО2 is a trigger of conformational transitions in the hemoglobin molecule, simultaneously with oxygen transport, hemoglobin signals to different metabolic systems about oxygen conditions in the environment. The studies revealed that in the conditions of vibration, the activity of membrane-associated catalase increased by 40–50% in the frequency range of 12–24 Hz (amplitude 0.5 ± 0.04 mm), by 20–30% in the amplitude of 0.9 mm, but after about 100–120 min exposure the enzyme activity decreased even below the control level. There was a dose-dependent accumulation of membrane-bound hemoglobin during exposure to vibration. In the membrane-bound fraction of hemoglobin, oxyhemoglobin had the highest content (60–80%), while the content of methemoglobin varied 5–20%. During vibrations in the frequency range 12–28 Hz, 0.5 mm, we recorded 10–30% increase in oxyhemoglobin. With increase in the vibration amplitude (0.9 mm) in the frequency range of 16–32 Hz, constant content of oxyhemoglobin was noted at the beginning of the experiment, which tended to decrease during the last exposure time. Frequency of 32 Hz caused increase in the deoxyhemoglobin content in the membrane-bound fraction. The content of methemoglobin (metHb) in erythrocytes significantly increased during exposure to the frequency range of 12–24 Hz, with the amplitude of 0.5 mm (1.3–2.4 times). During the exposure to frequencies of 28 and 32 Hz, we observed the transition of methemoglobin to hemichrome. The content of methemoglobin in the cells was lower and decreased at the end of the experiment when the vibration amplitude was 0.9 mm. In these experimental conditions, no increase in hemichrome content in the membrane-bound fraction was recorded. Therefore, the degree of binding of catalase and hemoglobin with the membrane of erythrocytes that were exposed to vibration and the changes in the content of ligand forms in the composition of membrane-bound hemoglobin are dose-dependent. Low-frequency vibration initiates O2-dependent processes in erythrocytes. Targets of such an influence are nanobubbles of dissolved air (babstons), retained on the surface of erythrocytes due to Coulomb interactions, capable of coagulation and increase in size under the action of vibration. At first, the consequences of these processes are increase in oxygen content in the surface of erythrocytes, and then decrease as a result of degassing. Thus, increase in oxygen content on the surface initiates redox reactions, whereas decrease in oxygen content leads to reconstruction of metabolic processes oriented at overcoming hypoxia.

Effects of moderate-intensity intermittent hypoxic training on health outcomes of patients recovered from COVID-19: the AEROBICOVID study protocol for a randomized controlled trial

BackgroundRecent studies point to a lower number and reduced severity of cases in higher altitude cities with decreased oxygen concentration. Specific literature has shown several benefits of physical training, so, in this sense, physical training with hypoxic stimulus appears as an alternative that supports the conventional treatments of the COVID-19 patient’s recovery. Thus, this study’s primary aim is to analyze the effects of moderate-intensity intermittent hypoxic training on health outcomes in COVID-19 recovered patients.MethodsA clinical trial controlled double-blind study was designed. Participants (30–69 years old) will be recruited among those with moderate to severe COVID-19 symptoms, approximately 30 days after recovery. They will be included in groups according to the training (T) and recovery (R) association with hypoxia (H) or normoxia (N): (a) TH:RH, (b) TN:RH, (c) TN:RN, and last (d) the control group. The 8-week exercise bike intervention will be carried out with a gradual load increase according to the established periods, three times a week in sets of 5 min, 90 to 100% of the anaerobic threshold (AT), and a 2.5-min break. Blood will be collected for genotyping. First, after 4 weeks (partial), after 8 weeks, and later, 4 weeks after the end of the physical training intervention, participants will perform assessments. The primary outcome is the maximum oxygen consumption (VO2peak). The secondary outcomes include lung function, inflammatory mediators, hematological, autonomic parameters, AT, body composition analysis, quality of life, mental health, anthropometric measurements, and physical fitness. The statistical analysis will be executed using the linear regression model with mixed effects at a 5% significance level.DiscussionThis study is designed to provide evidence to support the clinical benefits of moderate-intensity intermittent hypoxic training as a part of the treatment of patients recovered from COVID-19. It may also provide evidence on the efficacy and safety of intermittent hypoxic training in different health conditions. Lastly, this study presents an innovative strategy enabling up to 16 participants in the same training session.Trial registrationClinicalTrials.gov RBR-5d7hkv. Registered after the start of inclusion on 3 November 2020 with the Brazilian Clinical Trials Registry

Evaluation of PAO adaptability to oxygen concentration change: Development of stable EBPR under stepwise low-aeration adaptation

Recent research has shown the adaptability of Biological Nutrient Removal (BNR) systems to very low level dissolved oxygen (DO) concentration, mainly focusing in the nitrification ability that maintains the nitrogen oxidation process even at very low DO levels. Although step-wise aeration decrease on Enhanced Biological Phosphorus Removal (EBPR) is not fully comprehended. This study investigated the effect of reaching micro-aeration with adaptation strategies on EBPR performance. A step-wise oxygen concentration decrease, arriving at an average aeration level of 0.4 mgO2/L was evaluated, with an outcome of approximately 90 % phosphorus removal efficiency. Compared with different aeration modes, the highest phosphorus (P)-removal efficiency, P-release and lowest effluent phosphorus was achieved in gradual DO decrease strategy. On the other hand, an instant decrease in aeration from stable EBPR process from 2 mgO2/L to 0.4 mgO2/L adversely impacted P-removal by decreasing the efficiency to average 60 % and deteriorating the phosphorus removing microbial consortium. Comparison of results between instant and gradual DO-decrease, indicated the sensitivity of microorganisms to aeration. Microbial adaptation to decreased oxygen availability is crucial to reach high process performance. This study proposes, a potential aeration mode, which contributes in reduction of energy consumption in BNR systems through wastewater treatment.

Preparation and Characterization of Polyethylenimine Functionalized Reduced Graphene Oxide for Thermoelectric Applications

A facile and rapid hydrothermal route is used to synthesize the reduced graphene oxide (rGO) using polyethyleneimine (PEI) as a reducing agent. Structural and morphological studies confirm the degree of reduction, which is also verified by Raman analysis. Synthesized rGO has a nanosheet-like structure with wrinkles and folded regions. Hall measurements were taken at room temperature and measured its carrier concentration, resistivity, and mobility. Raman spectrum confirms that there is a change in shift while introducing a polymer. Thermoelectric characterizations were taken and found a decrease of oxygen content in rGO compared to GO. The values of Carrier concentration, resistivity and mobility are determined by Hall measurements at room temperature were rGO (p-type) is 3.95 × 1019 (cm3), 2.71 × 10−3 (ohm-cm), 58.3 (cm2 V−1 s−1) where for (n-type) rGO is 1.53 × 1020 (cm−3), 2.57 × 10−3 (ohm-cm), 15.9 (cm2 V−1 s−1) respectively. The carrier concentration of P-type rGO is higher when compared to n-type rGO. We believe that prepared reduced graphene oxide (rGO) will be used for wearable thermoelectric applications.

Physical and chemical mechanisms that influence the electrical conductivity of lignin-derived biochar

Lignin-derived biochar is a promising, sustainable alternative to petroleum-based carbon powders (e.g., carbon black) for polymer composite and energy storage applications. Prior studies of these biochars demonstrate that high electrical conductivity and good capacitive behavior are achievable. However, these studies also show high variability in electrical conductivity between biochars (∼10−2–102 S/cm). The underlying mechanisms that lead to desirable electrical properties in these lignin-derived biochars are poorly understood. In this work, we examine the causes of the variation in conductivity of lignin-derived biochar to optimize the electrical conductivity of lignin-derived biochars. To this end, we produced biochar from three different lignins, a whole biomass source (wheat stem), and cellulose at two pyrolysis temperatures (900 °C, 1100 °C). These biochars have a similar range of conductivities (0.002 to 18.51 S/cm) to what has been reported in the literature. Results from examining the relationship between chemical and physical biochar properties and electrical conductivity indicate that decreases in oxygen content and changes in particle size are associated with increases in electrical conductivity. Importantly, high variation in electrical conductivity is seen between biochars produced from lignins isolated with similar processes, demonstrating the importance of the lignin’s properties on biochar electrical conductivity. These findings indicate how lignin composition and processing may be further selected and optimized to target specific applications of lignin-derived biochars.

Effect of Oxygen Impurity on Thermal Conduction Rate of Polycrystalline Si3N4

Herein, the thermophysical properties and microstructures of the densified Si3N4, which are prepared by using MgO, Y2O3, and oxygen getter as sintering additives via conventional hot‐pressing sintering and followed by postheat treatment, are reported. Herein, it is found out that the sample using 5 mol.% of MgO, 2 mol.% of Y2O3, and 1.5 mol.% of Nb has the optimized thermal conductivity of 108 W m−1·K. Furthermore, increased rate of thermal conduction in the range of 10–15% is mainly originated from the decrease in the lattice oxygen contents of the grains in Si3N4 based on electron spin resonance (ESR) analysis.

Relation between crystal structure and lattice oxygen content of sintered reaction‐bonded silicon nitride

AbstractWhen reaction‐bonded silicon nitride containing MgO/Y2O3 additives is sintered at three different temperatures to form sintered reaction‐bonded silicon nitride (SRBSN), the thermal conductivity increases with sintering temperature. The β‐Si3N4 (silicon nitride) crystals of SRBSN ceramics were synthesized and characterized to investigate the relation between the crystal structure and the lattice oxygen content. The hot‐gas extraction measurement result and the crystal structure obtained using Rietveld analysis suggested that the unit cell size of the β‐Si3N4 crystal increases with the decrease in the lattice oxygen content. This result is reasonable considering that the lattice oxygen with the smaller covalent radius substitutes nitrogen with the larger one in the β‐Si3N4 crystals. The lattice oxygen content decreased with increasing sintering temperature which also correlated with increase in thermal conductivity. Moreover, it is noteworthy from the viewpoint that it may be possible to apply the lattice constant analysis for the nondestructive and simple measurement of the lattice oxygen content that deteriorates the thermal conductivity of the β‐Si3N4 ceramics.

Three-Dimensional Fluorescent Imaging to Identify Multi-Paths in Polymer Aging.

It is of great significance to disclose the diverse aging pathways for polymers under multiple factors, so as to predict and control the potential aging evolution. However, the current methods fail to distinguish multiple pathways (multi-paths) of polymer aging due to the lack of spatiotemporal resolution. In this work, using polyimide as a model polymer, the hydroxyl, carboxyl, and amino groups from the polyimide aging process were labeled using specific fluorescent probes through boron-oxygen, imine, and thiourea linkages, respectively. When the excitation and emission wavelengths of each fluorescent probe were controlled, the multi-paths in polyimide aging can be visualized individually and simultaneously in three-dimensional fluorescent images. The overall aging process under hydrothermal treatment was destructured into the pyrolysis and hydrolysis pathways. Three-dimensional dynamic studies discovered that the increased humidity, along with the decreased oxygen content, could hamper the pyrolysis reaction and accelerate the hydrolysis reaction, leading to severe degradation of the overall polyimide aging. More importantly, the oxygen showed a higher regulation coefficient in accelerating the pyrolysis reaction, than the water vapor in motivating the hydrolysis reactions. Such a multidimensional identification methodology is able to guide the long-term use of polymers and control their aging process to a harmless direction in advance by tuning the contents of oxygen and water vapor.

Techno-economic and life cycle analysis of biofuel production via hydrothermal liquefaction of microalgae in a methanol-water system and catalytic hydrotreatment using hydrochar as a catalyst support

The hydrochar, a by-product of hydrothermal liquefaction (HTL) of algal biomass, was utilized through two methods; combustion and activation, for its usage as a source of heat and a catalyst support for hydrodeoxygenation (HDO) process in the production of algal biofuels. In this study, techno-economic analysis (TEA) and life cycle assessment (LCA) of algal biofuels production in a two-stage process (HTL and HDO) were investigated. Aspen plus simulation and SimaPro software were used to analyze process economics and greenhouse gas (GHG) emissions. Microalgae at 200 dry metric tonnes day−1 was the basis for its conversion to biocrude oil through HTL in the methanol-water system followed by catalytic upgrading to produce biofuels. According to HTL experimental results, maximum biocrude oil yield of 57.8 wt% was obtained using microalgae-solvent mass ratio and methanol-water mass ratio of 1:5 and 3:1, respectively. Produced biocrude oil contained 14.5 wt% of oxygen and HHV of 33.4 MJ kgbiocrude oil−1 which required upgrading to be utilized as a transportation fuel. HDO was employed to enhance the quality of biocrude oil with decrease in oxygen content (3.1 wt%) and increase in HHV (42 MJ kgbiofuel−1). The minimum fuel selling price (MFSP) for using method #2 (activation) was 2.2 $ L−1 to breakeven the cost of operation, which was about 10% lower than that from method #1 (combustion). The GHG emissions performance was estimated at −1.13 gCO2-eq MJ−1 indicating the significant GHG emissions reduction compared to petroleum-based fuels production.

Water column poly-aromatic hydrocarbon anomalies measured with submersible gliders in the Angolan natural oil seepage province

Fluorescence sensors mounted on unmanned underwater gliders open new ways of investigation to detect dissolved hydrocarbons in seawater. A glider was deployed for 20 days to monitor biogeochemical and physical signals associated with natural hydrocarbon seepages within the first 700 m in the Angolan waters. The glider was equipped with fluorometers (MiniFluo-UV) to measure the concentrations of polycyclic aromatic hydrocarbons (PAH) of interest, i.e. naphthalene, phenanthrene, fluorene and pyrene. A continuous PAH-like signal detected within the 70 m layer below the sea surface is associated with high chlorophyll concentration in the deep chlorophyll maximum. Vertical PAH-like anomalies forming either strong spikes or diffuse columns down to 700 m are observed at the exact location of oil seep sites identified on Synthetic Aperture Radar satellite images. An ~200 m thick layer of enhanced PAH-like concentration, topped by a thermo/pycnocline identified at 280–300 m water depth, is measured in concomitance with the decrease in oxygen concentration. The concomitance of these signals suggests that lower oxygen concentrations induce a preservation of hydrocarbons within the eastern Atlantic oxygen minimum zone. Even if the absence of in-situ measurements limits the understanding of physical and biogeochemical processes affecting PAH concentrations, the measurements conducted at the edges of the OMZ suggests a relationship with microbial activity and organic matter dynamics in this layer. The results presented here show that gliders equipped with PAH sensors represent a promising means for monitoring hydrocarbons in the oceans, especially when they are coupled with other systems (i.e. Synthetic Aperture Radar).

Heat effects and kinetics of coal spontaneous combustion at various oxygen contents

In order to explore the effect of oxygen concentration on the exothermic characteristics of coal spontaneous combustion (CSC), the coal exothermic reaction process under different oxygen concentrations was analyzed with the aid of synchronous thermal analyzer. Moreover, the Gaussian function was adopted to perform the multimodal fitting for the oxidation exothermic stage of CSC, and the kinetic calculation of the fitting results was carried out. The following research results were obtained. Oxygen-depleted conditions can reduce the heat release of coal, delay the occurrence of the characteristic temperature point and prolong the reaction time. The coal oxidation exothermic process results from the superposition of three reaction mechanisms, namely oxidative decomposition, gas-phase combustion and solid-phase combustion, which are all inhibited under oxygen-depleted conditions. Besides, oxidative decomposition and gas-phase combustion tend to convert to solid-phase combustion under oxygen-depleted conditions. The apparent activation energy and the pre-exponential factor of coal are reduced as the oxygen concentration decreases. The CSC reaction intensity declines under oxygen-depleted conditions, so CSC can be suppressed by reducing the oxygen concentration. Nevertheless, under oxygen-depleted conditions, CSC lasts longer and is more difficult to extinguish. In addition, coal that is hard to spontaneously combust is also difficult to be extinguished. This research conduces to the study on CSC mechanism and the prevention and control of CSC hazards under oxygen-depleted conditions.

Study on the shouting breathing pattern while jogging wearing a mask

Because of the COVID-19 epidemic, many countries have made the obligation to wear masks normal. Wearing masks in public places has become a must. At present, wearing a mask to participate in sports makes it very common. People seek to gain health through exercise but ignore the potential respirato-ry health threat. That is, wearing a mask will cause a decrease in oxygen content in the body. This neg-ative impact becomes more prominent as the wear-ing time and oxygen consumption increase. To pro-tect people from viruses and enjoy a healthy life. This paper proposes a breathing pattern that im-proves blood oxygen saturation while wearing a jogging mask and walking. Namely, shouting breathing pattern. Use a pulse oximeter to measure the blood oxygen saturation of running at different speeds and compare the normal breathing pattern and the shouting breathing pattern. The results show that the shouting breathing pattern has a sig-nificant improvement in the blood oxygen satura-tion of low-speed walking and medium-speed jog-ging.

Dysregulation of bisphosphoglycerate mutase during in vitro maturation of oocytes.

Oxygen is vital for oocyte maturation; however, oxygen regulation within ovarian follicles is not fully understood. Hemoglobin is abundant within the in vivo matured oocyte, indicating potential function as an oxygen regulator. However, hemoglobin is significantly reduced following in vitro maturation (IVM). The molecule 2,3-bisphosphoglycerate (2,3-BPG) is essential in red blood cells, facilitating release of oxygen from hemoglobin. Towards understanding the role of 2,3-BPG in the oocyte, we characterized gene expression and protein abundance of bisphosphoglycerate mutase (Bpgm), which synthesizes 2,3-BPG, and whether this is altered under low oxygen or hemoglobin addition during IVM. Hemoglobin and Bpgm expression within in vivo matured human cumulus cells and mouse cumulus-oocyte complexes (COCs) were evaluated to determine physiological levels of Bpgm. During IVM, Bpgm gene expression and protein abundance were analyzed in the presence or absence of low oxygen (2% and 5% oxygen) or exogenous hemoglobin. The expression of Bpgm was significantly lower than hemoglobin when mouse COCs were matured in vivo. Following IVM at 20% oxygen, Bpgm gene expression and protein abundance were significantly higher compared to in vivo. At 2% oxygen, Bpgm was significantly higher compared to 20% oxygen, while exogenous hemoglobin resulted in significantly lower Bpgm in the COC. Hemoglobin and 2,3-BPG may play a role within the maturing COC. This study shows that IVM increases Bpgm within COCs compared to in vivo. Decreasing oxygen concentration and the addition of hemoglobin altered Bpgm, albeit not to levels observed in vivo.

Asphyxia with a reduced oxygen content in the environment (clinical lecture)

Asphyxia due to a decrease in oxygen concentration in the inhaled air is not common. Nevertheless, the mass media fairly regularly inform the population about its episodes in wine cellars, silos, and children in closed spaces. Quite a serious problem is exogenous hypoxia in miners as a result of accidents with the release of firedamp, carbon dioxide poisoning of submarine crews in case of failure of ventilation systems. The modern extreme sports enthusiast who are actively engaged in mountain tourism and mountaineering, speleology (including diggers), amateur piloting of sports aircraft and balloons, diving, etc. are subject to such lesions. In the available special literature sources on the topic “Asphyxiation due to a decrease in the concentration of oxygen in the environment”, there are almost no reports related to lifetime pathogenetic characteristics, diagnosis, and the basics of providing medical care to such victims. There are isolated recommendations on the provision of medical care for mountain sickness, while other options for exogenous asphyxia are considered only from the standpoint of forensic medical examination, in most cases — posthumously. Based on isolated domestic and foreign research works, personal theoretical and clinical experience, we have developed an algorithm for diagnosis and medical care at the stages of the route of a victim with exogenous hypoxia.

Electron structure and magnetic properties of self-doped Pr 1-xMnO3+δ manganites: XANES and EXAFS study. Comparing with A- and B-site doped perovskites

The local electronic and crystal structures of self-doped Pr1-xMnO3+δ (x = 0.0 and 0.2) perovskites are studied by x-ray absorption spectroscopy at Mn K-, Mn L- and O K-edges. The Mn K-edge shifts towards higher energy with increasing x indicating the increase in average manganese valence, which, in turn, leads to an increase in magnetization. The Mn L-edge spectra display a splitting into L3(2p3/2) and L2(2p1/2) peaks which is caused by core hole spin-orbit coupling. The intensities of 2p3/2 and 2p1/2 peaks increase with x, which correlates with the increase in magnetization and results from the change in hybridization between O 2p and Mn 3d orbitals. Altering x do not affect the O K-pre-edge spectra indicating no changes in Fermi level. Difference in relation of magnetic properties to electron structure in self-doped manganites and oxides doped in A- and B-positions of perovskites ABO3 cell is underlined. The Fourier transform of EXAFS spectra shows the decrease in oxygen and praseodymium contents and the formation of trivalent manganese anti-site defects in praseodymium position with increasing x.