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Long-distance oil pipeline is the most economical way to transport the crude oil and liquid chemical raw materials. The spillage liquid may enter the covered drain to form the flame spread over sub-flash liquid fuel. In this paper, a self-designed fuel-storable quartz glass pipe with the size of 100 cm long and 10 cm inner diameter is used to simulate a long-narrow confined space. The n-butanol flame spread behavior in the circular confined space is investigated by controlling the sealing ratio of the tube. The results show that the flame spreading behavior in the confined space is significantly different from that in the open space. There is the flame shuttle behavior at the sealing ratio β = 10% and the self-extinguishing behavior of the flame occurs at β = 55%. As the sealing ratios β > 10%, there is an obvious "retraction" behavior, resembling flame spreading over a hydrocarbon fuel in an open environment. However, the controlling mechanism is essentially different. For flame spread over butanol in a tube, the flame retreating is due to the insufficient oxygen supply. By contrast, for the flame spread over hydrocarbon fuel in an open space, the flame retreating is due to the evident difference of the flashpoint and fire point of the hydrocarbon fuel. The flame pulsation frequency increases from 2.0 to 5.7 Hz as the sealing ratio increases from β = 2% to 40%; then, it decreases to 1.3 Hz at β = 55%. The increase of the pulsation frequency in the initial stage indicates that the flame burns inadequately due to the reduced oxygen supply in the large sealing ratio. At β = 2%, the instantaneous velocity alternates between a low speed of 1–3 cm s−1 and a high speed of 5–8 cm s−1, with an average velocity of 1.9 cm s−1. This flame spreading behavior is regarded as the quasi-uniform propagation. At β = 45%, the average velocity reaches 2.3 cm/s. At β = 55%, the average velocity of flame is 0.54 cm s−1, indicating that the flame is difficult to spread forward. When the flame passes through the oxygen concentration sensor, there is a low oxygen concentration valley in the range of 1–5%. In middle area of the tube, the combustion can maintain owing to the oxygen concentration below 12%. This paper provides some theoretical support and guidance for fire safety and rescue in the long-narrow confined space. [ABSTRACT FROM AUTHOR]

We re-examined the reported increase in mitochondrial ROS production during acute hypoxia in cells. Using the Amplex Ultrared/horseradish peroxidase assay we found a decrease, not increase, in hydrogen peroxide release from HEK293 cells under acute hypoxia, at times ranging from 1 min to 3 h. The rates of superoxide/hydrogen peroxide production from each of the three major sites (site I Q in complex I and site III Qo in complex III in mitochondria, and NADH oxidases (NOX) in the cytosol) were decreased to the same extent by acute hypoxia, with no change in the cells' ability to degrade added hydrogen peroxide. A similar decrease in ROS production under acute hypoxia was found using the diacetyldichlorofluorescein assay. Using a HIF1α reporter cell line we confirmed earlier observations that suppression of superoxide production by site III Qo decreases HIF1α expression, and found similar effects of suppressing site I Q or NOX. We conclude that increased mitochondrial ROS do not drive the response of HIF1α to acute hypoxia, but suggest that cytosolic H 2 O 2 derived from site I Q , site III Qo and NOX in cells is necessary to permit HIF1α stabilization by other signals. [Display omitted] [ABSTRACT FROM AUTHOR]

BACKGROUND: Intervertebral disc degeneration is a condition caused by the combined effects of various factors, such as cellular apoptosis, oxidative stress, and inflammatory responses. Currently, it is believed that the core of this condition lies in the degeneration and apoptosis of nucleus pulposus cells (NPCs). However, the specific pathological mechanisms remain unclear. OBJECTIVE: By investigating the expression of the phosphatidylinositol-3 kinase (PI3K)/protein kinase B (Akt)/hypoxia-inducible factor 1-alpha (HIF-1α) signaling pathway and the apoptosis of NPCs under different oxygen concentrations, to clarify the biological characteristics of NPCs under varying oxygen levels, and to explore the mechanisms of intervertebral disc degeneration. METHODS: Normal and degenerated NPCs were collected. The second-generation cells were used for imaging identification. The third-generation cells were cultured in the following conditions: 37°C, air, 100% humidity. Leibovitz’s medium containing 100 μmol/L CoCl2 and 10% fetal bovine serum medium containing 100 μmol/L H2O2 were used to create distinct oxygen concentration environments for the third-generation cells, allowing for the investigation of cellular responses and behaviors under normal, low oxygen, and oxidative stress conditions. The third-generation cells were divided into six groups: normal NPCs+hypoxia, normal NPCs+normoxia, normal NPCs+oxidative stress, degenerated NPCs+hypoxia, degenerated NPCs+normoxia, and degenerated NPCs+oxidative stress groups. Cell viability and proliferation were assessed using the cell counting kit-8 method. Cell apoptosis was detected using flow cytometry. RT-PCR and western blot assay were utilized to examine the protein and mRNA expression levels of PI3K, AKT, and HIF-1α. RESULTS AND CONCLUSION: At different oxygen concentrations, the cell proliferation rate of both normal and degenerated NPCs decreased as the oxygen concentration increased. Conversely, the apoptosis rate increased as the oxygen concentration rose (P < 0.05). With the normal NPCs+hypoxia group as the control group, the effect of degenerated NPCs on the apoptosis rate was highly significant (P < 0.001). Oxygen concentration had a highly significant impact on both NPC proliferation rate and apoptosis rate (P < 0.001). The interaction between cell degeneration and oxygen concentration significantly affected both NPC proliferation and apoptosis rates (P < 0.05). At different oxygen concentrations, the protein and mRNA expression levels of PI3K, AKT, and HIF-1α in normal NPCs were highest under low oxygen concentration, followed by oxidative stress environment, and lowest under normoxia. In degenerated NPCs, the protein and mRNA expression levels of PI3K, AKT, and HIF-1α decreasd as the oxygen concentration increased. The protein and mRNA expression levels of PI3K and Akt in normal NPCs were significantly higher than those in degenerated NPCs (P < 0.05). With the normal NPCs+hypoxia group as the control group, the effects of normal or degenerated NPCs, as well as oxygen concentration, on the protein and mRNA expression of PI3K, AKT, and HIF-1α were highly significant. The interaction between cell degeneration and oxygen concentration also had an extremely significant effect on the protein and mRNA expression of PI3K, AKT, and HIF-1α (P < 0.001). To conclude, there is a close correlation between the proliferation and apoptosis of NPCs and both oxygen concentration and the cellular functional state. The PI3K/Akt/HIF-1α signaling pathway exhibits antagonistic regulatory effects under various cellular functional states and different oxygen concentration environments. The mechanism may be associated with the activation of the PI3K/Akt signaling pathway, which consequently transcribes HIF-1α, thus maintaining the balance of reactive oxygen species metabolism. This pathway plays a significant role in inhibiting oxidative stress, antagonizing NPCs apoptosis, and consequently delaying intervertebral disc degeneration. [ABSTRACT FROM AUTHOR]

To study the effect of pyrite on coal spontaneous combustion characteristics in low-rank coal under an oxygen atmosphere in goaf, this paper selected PZ brown coal impregnated with pyrite and its reaction products and monitored the changes in the generation of characteristic gases CO and CO2 during the programmed heating process of coal samples. The experiment found that oxygen concentration has the greatest impact on the spontaneous combustion characteristics of coal with added Fe3+. When the oxygen concentration in goaf coal increases to 9%, the promotion rate of high sulfur coal spontaneous combustion is the highest, which easily increases the range of goaf spontaneous combustion risk areas. When the temperature rises to 60°C, the catalytic effect of pyrite reaction products on coal spontaneous combustion is greatly enhanced. Through FTIR testing, it was found that Fe3+ ions, as strong oxidative free radicals, promote the reaction of –CH2–, –COOH, and –OH in coal at low oxygen concentrations, leading to a further increase in the tendency of coal to self ignite at low oxygen concentrations. [ABSTRACT FROM AUTHOR]

In the tumor microenvironment (TME), the interaction between cancer cells and the microvascular network plays a crucial role in cancer progression. It is also well known that an extremely low oxygen concentration is generated in the TME. However, the effects of oxygen concentration on the interaction between cancer cells and the microvascular network remain poorly understood. In the present study, we developed a microfluidic device with three gel channels and used this device to co-culture cancer cells and a microvascular network. We then investigated the cellular dynamics at different oxygen concentrations. Cancer cells and cells forming a microvascular network (endothelial cells and fibroblasts) were separately mixed with fibrin gels and placed in separate gel channels that flanked a middle gel channel lacking cells. During a seven-day co-culture, the dynamics of cancer cells and formation of a three-dimensional microvascular structure were observed. Cell culture was conducted at three different oxygen concentrations: atmospheric oxygen (21% O2), physiological normoxia (5% O2), and physiological hypoxia (1% O2, resembling the TME). Inspection revealed that cancer cells migrated toward the microvascular network under the co-culture conditions, a property that was potentiated at lower oxygen levels. Under physiological normoxia, endothelial cells formed a thick, dense microvascular network rather than migrating towards the cancer cells. In contrast, under physiological hypoxia, endothelial cells did not exhibit angiogenesis toward cancer cells. These results suggest that the microfluidic device described here will be useful for investigating the interactions between cancer cells and microvascular network under various oxygen conditions. [ABSTRACT FROM AUTHOR]

We studied positive streamers with a 5 mm gap under 20–101 kPa pressure and 1%–31% O2 concentrations conditions using a 2D axisymmetric fluid model based on local field approximation. As the pressure decreases from 101 kPa to 20 kPa, the axial reduced electric field, the mean electron energy and the electron diffusion coefficient increase, which leads to the acceleration of the streamer propagation velocity and the increase of the streamer channel radius. The opposite change of ionization cross section and gas molecular density caused by the decrease of pressure leads to the non-monotonic change of the peak of net ionization rate. At medium-low pressure, there is a wider ionization region at the streamer head. As the O2 concentration decreases from 31% to 1% in N2/O2, the streamer propagation velocity decreases. When the O2 concentration drops to 1%, the streamer velocity decreases with a descent gradient of nearly 4 times, compared to 11% O2. Based on the space charge effect and chemical reaction rate, a possible mechanism is proposed to explain the abrupt change in the streamer velocity. [ABSTRACT FROM AUTHOR]

The effect of different oxygen concentration conditions on the heat release behaviour of bituminous coal during spontaneous combustion was investigated. Thermal analysis experiments were conducted using differential scanning calorimetry (DSC) and laws governing feature peak changes. Heat flow curves were utilised to identify thermal reaction stages, and the impact of oxygen concentration on heat flows during spontaneous coal combustion (SCC) was assessed. The determinants of heat release rates according to temperature and different oxygen concentration conditions were shown. The heat release process exhibited varying heat proportions at distinct stages. Using the feature point analysis method, the DSC curves could be used to show the apparent activation energy of the total SCC process for different oxygen concentrations. Findings showed a noteworthy influence of oxygen concentration on the overall SCC process. As oxygen concentration increased, the characteristic peak of the heat flow curve appeared earlier, the range of heat release and its heat release temperature rose, and the apparent activation energy also increased. A critical oxygen concentration range, between 7 and 12%, was identified, causing fluctuations in the development process of SCC. This article provided a theoretical basis for further investigation into the SCC process and mechanisms. [ABSTRACT FROM AUTHOR]

In studying the effects of oxygen concentration and molecular structure on the morphologies of the soot particles produced by hydrocarbon fuels, ethylene and ethane were chosen as experimental fuels. With a Gülde laminar coaxial diffusion flame device, a soot particle device was used to sample soot particles at different oxygen concentrations (21%, 24%, 26%, 28%, and 31%) and at different heights above a burner (HABs = 10 mm, 20 mm, 30 mm, 40 mm, and 50 mm). High-resolution transmission electron microscopy (HRTEM) was used to scrutinize and analyze the soot particles at varying oxygen concentrations. The findings suggest that at the same oxygen concentration, ethylene produces brighter and taller flames. With an increase in the oxygen concentration, ethylene flames and ethane flames gradually decrease in height and become brighter. With an increase in the HAB, the average primary soot particle diameter (Dp) increases initially and then decreases, the fractal dimension (Df) increases, and the aggregates transition from strips and chains to clusters. At the same flame height (HAB = 30 mm), the Dp decreases, the Df increases, the carbon layer torsion resistance (Tf) and the carbon layer spacing (Ds) increase, and the carbon layer changes from a parallel arrangement to a curved arrangement to form denser network aggregations. [ABSTRACT FROM AUTHOR]

Previous research has unveiled a stem cell-like transcriptome enrichment in the aldehyde dehydrogenase-expressing (ALDHhigh) mesenchymal stromal cell (MStroC) fraction. However, considering the heterogeneity of MStroCs, with only a fraction of them presenting bona fide stem cells (MSCs), the actual potency of ALDH as an MSC-specific selection marker remains an issue. To address this, the proliferative and differentiation potential of individual ALDHhigh and ALDHlow MStroCs incubated at low oxygen concentrations, estimated to mimic stem cell niches (0.1% O 2), were assayed using single-cell clonal analysis, compared to standard conditions (20% O 2). We confirm that a high proliferative capacity and multi-potent MSCs are enriched in the ALDHhigh MStroC population, especially when cells are cultured at 0.1% O 2. Measurements of reduced/oxidized glutathione and mitochondrial superoxide anions with MitoSoX (MSX) indicate that this advantage induced by low oxygen is related to a decrease in the oxidative and reactive oxygen species (ROS) levels in the stem cell metabolic setup. However, ALDH expression is neither specific nor exclusive to MSCs, as high proliferative capacity and multi-potent cells were also found in the ALDHlow fraction. Furthermore, single-cell assays performed after combined cell sorting based on ALDH and MSX showed that the MSXlow MStroC population is enriched in stem/progenitor cells in all conditions, irrespective of ALDH expression or culture oxygen concentration. Importantly, the ALDHhighMSXlow MStroC fraction exposed to 0.1% O 2 was almost exclusively composed of genuine MSCs. In contrast, neither progenitors nor stem cells (with a complete absence of colony-forming ability) were detected in the MSXhigh fraction, which exclusively resides in the ALDHlow MStroC population. Our study reveals that ALDH expression is not exclusively associated with MSCs. However, cell sorting using combined ALDH expression and ROS content can be utilized to exclude MStroCs lacking stem/progenitor cell properties. [Display omitted] [ABSTRACT FROM AUTHOR]

SUMMARY: This study examines how the combination of layer breeder age and oxygen concentration in the incubator impacts Chorioallantoic (CAM) vascularization, embryo and chick organs, blood profiles, and organ histology at hatch. Nine hundred (900) eggs from 33 to 50 wk ISA breeders were incubated at different O2 levels (15%, 17%, and 21%). Results showed significant interactions between breeder age and oxygen levels, affecting liver and heart weights, blood indices, and CAM vascularity. Hypoxic conditions led to adaptive changes in embryonic organs, with notable differences between breeder age groups, suggesting that mild hypoxia can influence compensatory growth, depending on exposure stages.

To explore the changes in water status and protein characteristics of Tibetan pork (TP) under modified atmosphere packaging (MAP) with different oxygen concentrations compared to Duroc×Landrace×Yorkshire pork (DLY), the water holding capacity (WHC), water distribution, protein oxidation, and conformation of both types were determined. Results indicate that under MAP, TP pork and DLY pork exhibited higher water retention and lower protein oxidation compared to air packaging. However, with increased oxygen concentration in the MAP, protein oxidation intensified, leading to reduced WHC in the pork. Compared to DLY pork, TP pork in different packaging conditions maintained the integrity of protein secondary and tertiary structures, reducing protein cross-linking aggregation. The lower content of P3 in the two-dimensional relaxation spectra, shorter T1 and T2 relaxation times, and higher proton density suggest better water retention properties in Tibetan pork. These findings support the development of long-distance preservation and transportation technologies for TP pork.

To research the impact of oxygen consistency on the thermal dynamic characteristics and the change of gas products of weakly caking coal oxidation, differential scanning calorimetry and temperature programmed experiments were used to study, and the correlation between the intensity of heat release at distinct consistencies of oxygen and concentration of gas products was computed applying grey correlation method. The outcomes indicated that the coal low-temperature oxidation process can be categorized into three phases: speedy endothermic, slow endothermic, and exothermic. The apparent activation energy in the slow heat absorption phase exceeded the speedy endothermic stage, and the apparent activation energy in the heat release phase increased by 20.83 kJ/mol. The concentration of gas products generated at the spontaneous combustion process of coal growth when temperature went up. However, CH4 concentration increased with the temperature rising after 120 °C. C2H6 gas does not appear until 100 °C. C2H4 gas appeared after 90 °C. At various O2 consistencies, the correlation between exothermic intensity and CO2 remained the largest, the correlation between exothermic intensity and CO and CH4 was larger at lower oxygen consistencies. As concentration of oxygen increased, the correlation between exothermic intensity and C2H4 and C2H6 increased first and then decreased.

The conversion of methane in catalysis fields has aroused much attention for its abundant distribution in nature and it is environment-friendly. However, the C–H chemical breaking is a major challenge and requires proper catalysts for methane activation. Using first-principle calculations, we systematically explore the atomic configuration, interaction strength, dehydrogenation process and electronic properties of methane on noble metal Pt(111) and isoelectronic transition metal carbide WC(001) surface. The adsorption strength of methane activation on the WC(001) surface is stronger and the barrier of C–H bond breaking is smaller than that of the Pt(111) surface. Moreover, the oxygen concentration ranging from 40% to 60% coverage on the WC(001) surface benefits the methane activation and the energy barrier decreased to 0.26 ∼ 0.57 eV. The larger charge transfer emerges at the interface between methane and the WC(001) surface with or without oxygen coverage comparable to the Pt(111) surface. Our theoretical results can provide vital guidance for experimental synthesis conditions of methane activation and the transition metal carbide application in catalysts. [ABSTRACT FROM AUTHOR]

As a fossil fuel substitute, bio-jet fuel derived from inedible oilseed crops has the potential to improve energy security, decrease carbon footprint, and promote agricultural economy and social development. The efficient production of bio-jet fuels depends on the identification and characterization of eco-friendly and sustainable feedstocks. Brassica carinata (Arun Braun) cultivars are among the most significant industrial oilseeds that can be utilized as alternative feedstocks in the aviation industry. The study thoroughly evaluated four non-food Brassica carinata cultivars that are indigenous to Ethiopia to determine their suitability as substitute feedstocks for the production of bio-jet fuel. The effects of solvent extraction parameters were studied using response surface methodology with Box-Behnken design in an isothermal batch reactor. Physicochemical characterization, fatty acids profiling, ultimate analysis, analysis of metals and phosphorus concentration, Fourier-transform infrared spectroscopy characterization, and calorific value analyses were performed to characterize the properties of oils. Accordingly, oil yields ranged from 35.93 to 45.25%. Erucic acid (EA) was the most predominant fatty acid in all oils, accounting for 42–50%, of Derash and Yellow Dodolla oils, respectively, making Yellow Dodolla oil a super-high erucic acid oil. In comparison to the other oils, Yellow Dodolla was observed to be the least oxygenated oil, with a 7.80% oxygen content and oxygen to carbon ratio of 0.07, which may enable it to consume a very limited amount of hydrogen gas during hydrodeoxygenation in bio-jet fuel production. It was determined that, except for calcium and phosphorous levels in Tesfa, the concentrations of the metals and phosphorous were very small. Alkanes, alkenes, carboxylic acids, esters, alcohols, aromatics, and olefins were among the most significant and main functional groups identified. Our extraction and characterization results revealed that the Brassica carinata cultivars have very high oil contents, better physicochemical properties, excellent fatty acid profiles, and very low concentrations of heteroatoms (nitrogen, sulfur), metals and phosphorous concentrations, and very low level of oxygen to carbon ratios, making the oils, notably Yellow Dodolla oil, very high quality and promising alternative feedstocks for upgrading of the oils into bio-jet fuels through hydroprocessing pathway. [ABSTRACT FROM AUTHOR]

Understanding the characteristics of coal spontaneous combustion (CSC) in goaf under different porosities is crucial for comprehending the mechanism of CSC and its prevention and control. In this paper, a multi-field coupled model of CSC in the goaf, considering porosity variation, is developed to investigate the effect of porosity on the CSC characteristics in the goaf. The results indicate that, as the goaf depth increases, both porosity and permeability decrease. When the highest goaf porosity is 25%, the average airflow velocity is between 0.00134 and 0.00139 m/s. In contrast, the average airflow velocity in the goaf with a porosity of 40% is approximately six times greater than that of the goaf with a porosity of 25%. As the goaf porosity increases, the overall oxygen concentration, temperature, and oxidized zone area also rise. Moreover, the oxidation zone area can be quantified and visualized, thereby enabling more effective prediction of the CSC risk in the goaf. The findings of the study have a positive significance in guiding the prevention and control of coal fires. [ABSTRACT FROM AUTHOR]

Neisseria gonorrhoeae has developed resistance to every antibiotic currently approved for the treatment of gonorrhea, prompting the development of new therapies. The phenoxazine dye resazurin exhibits robust antimicrobial activity against N. gonorrhoeae in vitro but fails to limit vaginal colonization by N. gonorrhoeae in a mouse model. The lack of in vivo efficacy may be due to oxygen limitation as in vitro susceptibility assays with resazurin are conducted under atmospheric oxygen while a microaerophilic environment is present in the vagina. Here, we utilized broth microdilution assays to determine the susceptibility of N. gonorrhoeae to resazurin under low and atmospheric oxygen conditions. The minimal inhibitory concentration of resazurin for multiple N. gonorrhoeae clinical isolates was significantly higher under low oxygen. This effect was specific to resazurin as N. gonorrhoeae was equally susceptible to other antibiotics under low and atmospheric oxygen conditions. The reduced susceptibility of N. gonorrhoeae to resazurin under low oxygen was largely attributed to reduced oxidative stress, as the addition of antioxidants under atmospheric oxygen mimicked the reduced susceptibility to resazurin observed under low oxygen. Together, these data suggest oxygen concentration is an important factor to consider when evaluating the efficacy of new antibiotics against N. gonorrhoeae in vitro. [ABSTRACT FROM AUTHOR]

The construction of dams on large rivers significantly changes the hydrological regime. The morphology and functional features of floodplain water bodies have a significant impact on water quality parameters. The electrical conductivity, transparency, water temperature and dissolved oxygen content of 302 water bodies located in the Dnipro River floodplain were investigated. The variability of water quality indicators is explained by different sources of water supply to the floodplain reservoirs, as well as by the geological characteristics of the soil. The genesis of lakes of a certain shape is related to the geological and geomorphological conditions of the floodplain, which is the reason for the connection between the functional characteristics of water bodies and water quality indicators in them. Predictors of the probability of oxygen stress are the proximity of the sandy border to the reservoir and the elongated shape of the reservoir. [ABSTRACT FROM AUTHOR]

In this study, we created a 3D Artificial Skin Platform that can be used for the treatment of pigmentation by artificially realizing the skin of pregnant women. For the stable realization of 3D artificial skin, a bilayer hydrogel composed of collagen type I and fibrin was designed and applied to the study to reduce the tension-induced contraction of collagen type I, the extracellular matrix (ECM) of artificial skin, by dynamic culture. Oxygen concentration and 17β-Estradiol (E2) concentration, which are highly related to melanin production, were selected as parameters of the pregnancy environment and applied to cell culture. Oxygen concentration, which is locally reduced in the first trimester (2.5–3%), and E2, which is upregulated in the third trimester, were applied to the cell culture process. We analyzed whether the 3D artificial skin implemented in the 3D Artificial Skin Platform could better represent the tendency of melanin expression in pregnant women than cells cultured under the same conditions in 2D. The expression levels of melanin and melanin-related genes in the 2D cell culture did not show a significant trend that was similar to the melanin expression trend in pregnant women. However, the 3D artificial skin platform showed a significant trend towards a 2-6-fold increase in melanin expression in response to low oxygen concentrations (2.5%) and E2 concentrations (17 ng/mL), which was similar to the trend in pregnant women in vivo. These results suggest that 3D artificial skin cultured on the Artificial Skin Platform has the potential to be used as a substitute for human pregnant skin in various research fields related to the treatment of pigmentation. [ABSTRACT FROM AUTHOR]

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Objective: Gas embolism is a common complication of hysteroscopic surgery that causes serious concern among gynecologists and anesthesiologists due to the potential risk to patients. The factors influencing gas embolism in hysteroscopic surgery have been extensively studied. However, the effect of the oxygen concentration inhaled by patients on gas embolism during hysteroscopic surgery remains elusive. Therefore, we designed a double‐blind, randomized, controlled trial to determine whether different inhaled oxygen concentrations influence the occurrence of gas embolism during hysteroscopic surgery. Methods: This trial enrolled 162 adult patients undergoing elective hysteroscopic surgery who were randomly divided into three groups with inspired oxygen fractions of 30%, 50%, and 100%. Transthoracic echocardiography (four‐chamber view) was used to evaluate whether gas embolism occurred. Before the start of surgery, the four‐chamber view was continuously monitored. Results: The number of gas embolisms in the 30%, 50%, and 100% groups was 36 (69.2%), 30 (55.6%), and 24 (44.4%), respectively. The incidence of gas embolism gradually decreased with increasing inhaled oxygen concentration (P = 0.031). Conclusion: In hysteroscopic surgery, a higher oxygen concentration inhaled by patients may reduce the incidence of gas embolism, indicating that a higher inhaled oxygen concentration, especially 100%, could be recommended for patients during hysteroscopic surgery. Trial Registration: Chinese Clinical Trial Registry (https://www.chictr.org.cn/showproj.html?proj=53779, Registration number: ChiCTR2000033202). Synopsis: In hysteroscopic surgery, a higher oxygen concentration inhaled by patients may reduce the incidence of gas embolism. [ABSTRACT FROM AUTHOR]

The addition of hydrogen peroxide (H2O2) to cultured cells is widely used as a method to modulate redox-regulated cellular pathways, including the induction of programmed cell death in cell culture experiments and the testing of pro- and antioxidant compounds. Here, we assessed the effect on the cellular response to H2O2 of pre-adapting squamous cell carcinoma cells (A431) to the standard cell culture oxygenation of 18.6% O2, compared to cells pre-adapted to a physiological skin O2 concentration (3.0% O2). We showed that cells pre-adapted to 18.6% O2 resisted H2O2-induced cell death compared to cells pre-adapted to 3.0% O2 for 96 h prior to treatment with H2O2. Moreover, the enzymatic activities of catalase and glutathione reductase, as well as the protein expression levels of catalase, were higher in cells pre-adapted to 18.6% O2 compared to cells pre-adapted to 3.0% O2. H2O2-resistant cells, pre-adapted to 18.6% O2, exhibited increased nuclear Nrf-2 levels. It is concluded that A431 cells pre-adapted to standard cell culture oxygenation conditions resist H2O2-induced cell death. This effect may be related to their heightened activation of Nrf-2. [ABSTRACT FROM AUTHOR]

[Objective] As the main energy source in China, coal has an important strategic position in the country's economic development. China's coal-based energy structure model will not change in the short term, but coal mine accidents occur frequently. Mine fire is a major disaster that threatens safe coal mine production, which incurs huge economic losses and threatens the personal safety of miners and coal mine production. However, coal spontaneous combustion primarily causes mine fires. The occurrence mechanism of coal spontaneous combustion is highly complex and is affected by the inherent combustion characteristics of coal and external environmental factors. Therefore, it is necessary to comprehensively analyze various phenomena and characteristics in the process of coal spontaneous combustion and apply quantitative indicators to express to predict the risk and ensure the safe production of the mine. [Methods] Oxygen concentration is an important factor influencing coal oxidation reaction. In this paper, the temperature-programmed experimental system is used to conduct the spontaneous combustion experiment of coal samples with three oxygen concentrations of 20.9%, 10%, and 7% regarding the heat dissipation, oxidation, and asphyxiation zones in the goaf. The gas products at different temperature stages are collected, the effects of temperature and oxygen concentration on the concentration of gas products are analyzed, and the index gases are classified and evaluated in detail. [Results] The results show the following: (1) The cross-point temperature (CPT) decreases with the increase in the oxygen concentration. The cross-point temperature under dry-air conditions is 144.6 °C. The error between the CPT value calculated by the BM empirical relationship and the experimental data is only 6.08%. The higher the oxygen concentration, the smaller the critical temperature, and the higher the gas concentration. (2) The content of oxidation products increases with the oxygen concentration. When heating commences, minimal CO and CH4 gases are generated, but with the increase in the temperature, C2H4 and C2H6 gases appear gradually. The oxidation reaction of coal samples is primarily affected by temperature and oxygen concentration. At a certain temperature, the higher the oxygen concentration, the more intense the coal-oxygen composite reaction, and more gas products appear. (3) For different oxygen concentration environments, the regularity of generating CO gas is highly significant, which can be used as an indicator gas to evaluate the spontaneous combustion of coal. In dry air, the temperature of C2H4 is earlier than that of C3H6, implying that the existence of C2H4 indicates that the coal oxidation process has entered an accelerated stage. The emergence of C3H6 gas marks the transformation of the coal oxidation into strong oxidation. Recently, the programmed temperature rise experiment has become an important research field. [Conclusions] Through indoor experiments, students can deeply understand the mechanism of coal spontaneous combustion and the process of establishing the prediction index system and introduce the experiment into the classroom. This practical teaching approach not only helps students to apply theoretical knowledge to practical problems but also broadens their horizons and improves their interest in scientific research, achieving better teaching results. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to evaluate the association between the concentration and duration of oxygen therapy and the development and severity of retinopathy of prematurity (ROP). Additionally, it sought to examine the incidence of ROP at Naresuan University Hospital. Materials and Methods: A retrospective observational cohort study was conducted, utilizing data from the medical records of infants admitted to the Neonatal Intensive Care Unit at Naresuan University Hospital, Phitsanulok, Thailand, from January 1, 2016, to December 31, 2022. The duration of various oxygen therapies was recorded in hours, and the concentration of oxygen administered per hour was calculated as the average fraction of inspired oxygen for each infant. These data were subsequently analyzed using STATA version 11.0. Results: Out of 100 eligible infants, 27 (27%) were diagnosed with ROP at different severity levels: 17 infants (62.96%) with ROP stage 1, 9 infants (33.33%) with stage 2, and 1 infant (3.70%) with stage 3. There were no cases of Stage 4 or 5 ROP. The adjusted risk ratio revealed that infants receiving an average FiO2 of 0.3 or higher had a 1.64 times greater risk of developing ROP [95%CI 1.03-2.62], (P-value=0.038). Further analysis using mean difference regression showed a significant correlation between the duration of oxygen therapy and the severity of ROP. Conclusion: This study suggests that regulating oxygen therapy to not exceed an FiO2 of 0.3 and administering it strictly as needed may mitigate the risk of developing ROP and its severe manifestations. [ABSTRACT FROM AUTHOR]

A decline in atmospheric oxygen concentration is projected in the 21st century given the background of global warming. The Qinghai-Tibetan Plateau is located at a high altitude, and thus, it faces a hypoxia challenge; however, knowledge of the factors contributing to its atmospheric oxygen concentration is still lacking. Here, we conducted joint observations of ecosystem oxygen production and carbon sinks and near-surface atmospheric oxygen concentrations on the Qinghai-Tibetan Plateau and meteorological elements at Beijing Fangshan Station. Using seasonal differences and statistical methods, we calculated the relative contribution rates of vegetation to changes in atmospheric oxygen concentration. Our results indicate that solar radiation, atmospheric humidity, and ecosystem oxygen consumption and production have a significant impact on the atmospheric oxygen concentration, and the impact shows temporal and spatial differences. Vegetation significantly impacts the oxygen concentration, with a contribution rate of 16.7%–24.5%, which is underestimated in existing research. Our findings provide important insights into the factors that influence atmospheric oxygen concentration and highlight the contribution of vegetation. To better understand the oxygen dynamics of the Qinghai-Tibetan Plateau, we recommend further field observations of soil respiration and vegetation photosynthesis to clarify the contributions of carbon storage, carbon sinks and other factors to the near-surface atmospheric oxygen concentration. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The aim of the study was to explore the expression of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB/AKT)/hypoxia-induced factor-1 alpha (HIF-1α) signaling pathway and the apoptosis of nucleus pulposus cells (NPCs) under different oxygen concentrations to clarify the biological characteristics of NPCs and the molecular mechanism of intervertebral disc degeneration (IVDD). MATERIALS AND METHODS: Normal and degenerated human NPCs were collected. Leibovitz's medium with 100 μmol/L CoCl2 was used to establish a hypoxic culture environment, and 100 μmol/L H2O2 was used to establish an oxidative stress culture environment. Third-generation NPCs were divided into 6 groups: normal NPCs + hypoxia, normal NPCs + normoxia, normal NPCs + oxidative stress, degenerated NPCs + hypoxia, degenerated NPCs + normoxia, and degenerated NPCs + oxidative stress. Normal NPCs + hypoxia was used as the experimental control group. Cell viability and proliferation were detected by using the Cell Counting Kit- 8 (CCK-8) method. Cell apoptosis rate was assessed by flow cytometry, and expression levels of PI3K, AKT, and HIF-1α were determined by Real-Time-Polymerase Chain Reaction (RT-PCR) and Western blotting. RESULTS: The cell proliferation rate of both normal and degenerated NPCs decreased with increasing oxygen concentration. Conversely, the apoptosis rate increased as the oxygen concentration increased (p<0.05). Compared with the control group, whether the cells degenerated had a very significant impact on the apoptosis rate (p<0.001), and oxygen concentration also had a highly significant impact on both the cell proliferation rate and apoptosis rate (both p<0.001). The interaction between cell degeneration and oxygen concentration significantly affected both cell proliferation and apoptosis rates (p<0.05). Considering the expression levels of PI3K, AKT, and HIF-1α, normal NPCs had the highest levels under low oxygen concentrations, followed by oxidative stress and normoxia. In degenerated NPCs, the expression levels also decrease as the oxygen concentration increases. CONCLUSIONS: The PI3K/AKT/HIF-1α signaling pathway plays a significant role in inhibiting oxidative stress, antagonizing NPC apoptosis, and consequently delaying IVDD. [ABSTRACT FROM AUTHOR]

Taking Aspergillus niger and Penicillium citrinum as examples, the internet of things system was used to monitor the temperature, humidity and oxygen concentration of the incubator, and the influences of oxygen concentration on the growth of A. niger and P. citrinum were preliminarily studied. Through the preliminary study, it was found that the minimum oxygen concentration required for the growth of A. niger should be 0. 7% when the temperature was (28±1)℃, the humidity was 60%-80%, and the culture lasted for 7 days. High concentration oxygen could satisfy its aerobic metabolism and make its growth and development reach saturation state, while low concentration oxygen could not satisfy its aerobic metabolism and cause insufficient growth and development. The metabolic activity of A. niger stopped when the oxygen concentration in the system was as low as 0. 7%. The growth of P. citrinum was similar to the above rule in oxygen concentration. The study on the rule of the growth of common molds on silk cultural relics and the oxygen concentration and the oxygen concentration threshold provided the theoretical basis for the preservation of silk cultural relics and the development and design of its devices. [ABSTRACT FROM AUTHOR]

Incorporation of bovine serum-derived albumin formulation (AlbuMAX) into a basic culture medium, MEMa, enables the completion of in vitro spermatogenesis through testicular tissue culture in mice. However, this medium was not effective in other animals. Therefore, we sought an alternative approach for in vitro spermatogenesis using a synthetic medium without AlbuMAX and aimed to identify its essential components. In addition to factors known to be important for spermatogenesis, such as retinoic acid and reproductive hormones, we found that antioxidants (vitamin E, vitamin C, and glutathione) and lysophospholipids are vital for in vitro spermatogenesis. Moreover, based on our experience with microfluidic devices (MFD), we developed an alternative approach, the PDMS-ceiling method (PC method), which involves simply covering the tissue with a flat chip made of PDMS, a silicone resin material used in MFD. The PC method, while straightforward, integrates the advantages of MFD, enabling improved and uniform oxygen and nutrient supply via tissue flattening. Furthermore, our studies underscored the significance of lowering the oxygen concentration to 10-15%. Using an integrated cultivation method based on these findings, we successfully achieved in vitro spermatogenesis in rats, which has been a long-standing challenge. Further improvements in culture conditions would pave the way for spermatogenesis completion in diverse animal species. [ABSTRACT FROM AUTHOR]

The airways of cystic fibrosis (CF) patients are colonized by many pathogens and the most common is Pseudomonas aeruginosa, an environmental pathogen that is able to infect immunocompromised patients thanks to its ability to develop resistance to conventional antibiotics. Over 12% of all patients colonized by P. aeruginosa harbour multi-drug resistant species. During airway infection in CF, P. aeruginosa adopts various mechanisms to survive in a hostile ecological niche characterized by low oxygen concentration, nutrient limitation and high osmotic pressure. To this end, P. aeruginosa uses a variety of virulence factors including pigment production, biofilm formation, motility and the secretion of toxins and proteases. This study represents the first report that systematically analyzes the differences in virulence features, in normoxia and anoxia, of clinical P. aeruginosa isolated from CF patients, characterized by multi- or pan-drug antibiotic resistance compared to antibiotic sensitive strains. The virulence features, such as biofilm formation, protease secretion and motility, are highly diversified in anaerobiosis, which reflects the condition of chronic CF infection. These findings may contribute to the understanding of the real-world lifestyle of pathogens isolated during disease progression in each particular patient and to assist in the design of therapeutic protocols for personalized medicine. [ABSTRACT FROM AUTHOR]

In light of the low dissolved oxygen concentration in the deep sea, the corrosion mechanisms of the high entropy alloy (HEA) AlCoCrFeNi in artificial seawater with varying oxygen concentrations (2.0, 4.0, 7.0 mg/L) were studied. As the oxygen concentration decreases, the alloy's free corrosion potential decreases, and at 2.0 mg/L, the corrosion rate is 421 times higher than that at 7.0 mg/L. The corrosion form transforms from pitting to uniform corrosion. The primary reasons for this are the passivation film is thin under low oxygen concentration conditions, as well as the preferential dissolution of the alloy elements Al and Ni due to their high activity and “local acidizing” properties, respectively. In designing a super corrosion-resistant high entropy alloy for use in the deep sea, it is advisable to avoid the use of element Al and to add Ni with caution.

Adaptive response to physiological oxygen levels (physO2; 5% O2) enables embryonic survival in a low-oxygen developmental environment. However, the mechanism underlying the role of physO2 in supporting preimplantation development, remains elusive. Here, we systematically studied oxygen responses of hallmark events in preimplantation development. Focusing on impeded transcriptional upregulation under atmospheric oxygen levels (atmosO2; 20% O2) during the 2-cell stage, we functionally identified a novel role of HIF-1α in promoting major zygotic genome activation by serving as an oxygen-sensitive transcription factor. Moreover, during blastocyst formation, atmosO2 impeded H3K4me3 and H3K27me3 deposition by deregulating histone-lysine methyltransferases, thus impairing X-chromosome inactivation in blastocysts. In addition, we found atmosO2 impedes metabolic shift to glycolysis before blastocyst formation, thus resulting a low-level histone lactylation deposition. Notably, we also reported an increased sex-dimorphic oxygen response of embryos upon preimplantation development. Together, focusing on genetic and epigenetic events that are essential for embryonic survival and development, the present study advances current knowledge of embryonic adaptive responses to physO2, and provides novel insight into mechanism underlying irreversibly impaired developmental potential due to a short-term atmosO2 exposure.

Objective: In this study, we investigated the effect of various oxygen therapy regimens on oxygenation in patients with acute type A aortic dissection (AAD). Methods: A quasi-randomized controlled trial was conducted, in which patients with AAD hospitalized for surgery from June to September 2021 were assigned to the control group (patients received conventional oxygen therapy after postoperative mechanical ventilation, weaning, and extubation) and those who were admitted from October to December 2021 were assigned to the observation group [patients underwent optimally adjusted therapy based on the treatment of the control group, which mainly included prioritized elevation of positive end-expiratory pressure (PEEP) and restricted use of the fraction of inspired oxygen (FiO2)].The postoperative oxygenation index, blood gas analysis, and duration of mechanical ventilation were compared between the two groups. Results: There were significant differences in oxygenation observed at 2 h postoperatively between the groups. 12, 24, and 72 h postoperatively, the oxygenation index varied significantly between the two groups. There were statistically significant differences in the time effects of the oxygenation index and PaO2 between the two groups, as well as significant differences in the length of stay in the intensive care unit. Conclusion: For the postoperative care of patients with AAD, it is suggested that the minimum FiO2 required for oxygenation of patients be maintained. In addition, it is possible to enhance PEEP as a priority when PaO2 is low.

Incorporation of bovine serum-derived albumin formulation (AlbuMAX) into a basic culture medium, MEMα, enables the completion of in vitro spermatogenesis through testicular tissue culture in mice. However, this medium was not effective in other animals. Therefore, we sought an alternative approach for in vitro spermatogenesis using a synthetic medium without AlbuMAX and aimed to identify its essential components. In addition to factors known to be important for spermatogenesis, such as retinoic acid and reproductive hormones, we found that antioxidants (vitamin E, vitamin C, and glutathione) and lysophospholipids are vital for in vitro spermatogenesis. Moreover, based on our experience with microfluidic devices (MFD), we developed an alternative approach, the PDMS-ceiling method (PC method), which involves simply covering the tissue with a flat chip made of PDMS, a silicone resin material used in MFD. The PC method, while straightforward, integrates the advantages of MFD, enabling improved and uniform oxygen and nutrient supply via tissue flattening. Furthermore, our studies underscored the significance of lowering the oxygen concentration to 10–15%. Using an integrated cultivation method based on these findings, we successfully achieved in vitro spermatogenesis in rats, which has been a long-standing challenge. Further improvements in culture conditions would pave the way for spermatogenesis completion in diverse animal species.

In studying the effects of oxygen concentration and molecular structure on the morphologies of the soot particles produced by hydrocarbon fuels, ethylene and ethane were chosen as experimental fuels. With a Gülde laminar coaxial diffusion flame device, a soot particle device was used to sample soot particles at different oxygen concentrations (21%, 24%, 26%, 28%, and 31%) and at different heights above a burner (HABs = 10 mm, 20 mm, 30 mm, 40 mm, and 50 mm). High-resolution transmission electron microscopy (HRTEM) was used to scrutinize and analyze the soot particles at varying oxygen concentrations. The findings suggest that at the same oxygen concentration, ethylene produces brighter and taller flames. With an increase in the oxygen concentration, ethylene flames and ethane flames gradually decrease in height and become brighter. With an increase in the HAB, the average primary soot particle diameter (Dp) increases initially and then decreases, the fractal dimension (Df) increases, and the aggregates transition from strips and chains to clusters. At the same flame height (HAB = 30 mm), the Dp decreases, the Df increases, the carbon layer torsion resistance (Tf) and the carbon layer spacing (Ds) increase, and the carbon layer changes from a parallel arrangement to a curved arrangement to form denser network aggregations.

The objective of this study was to determine melatonin"s ameliorating effects against heat stress and oxygen tension in developing bovine embryos in vitro. The oocytes were collected from ovaries obtained from a local abattoir, followed by in vitro maturation, fertilization, and embryo culture. During in vitro culture, embryos were exposed to 5% (Group I) and 20% (Group II) oxygen tension with 10-3, 10-6, and 10-9 molar (M) melatonin, along with the control group without melatonin (Group III). Compared to the control group, melatonin at 10-6 and 10-9 concentrations increased in vitro development rates and decreased caspase 3/7 activity at 5% and 20% oxygen tension (P0.05). In conclusion, melatonin prevents the adverse effects of heat stress and O2 tension on preimplantation bovine embryos in vitro.

Objective To evaluate the effects of different oxygen concentrations on the oxygenation index of obese patients during the non-ventilation period after general anesthesia induction. Methods 75 American Society of Anaesthesiologists （ASA） gradeⅡ-Ⅲobese patients （30 kg/m22）， aged 18-65 years， were recruited and divided into H， M and L groups according to the inhaled oxygen concentration during anesthesia induction. Induction drugs were given according to the ideal body weight. After the patients’ eyelash reflex were absent and spontaneous respiration was terminated， the oropharyngeal airway was placed， the mandibular mask was supported with both hands and mechanical ventilation was pre-administered with oxygen （100% oxygen concentration in group H， 80% oxygen concentration in group M， and 60% oxygen concentration in group L）. The tracheal tube was intubated under the guidance of a visual light rod， and oxygen was temporarily not connected. The ventilator was connected when O2 saturation declined to 92%. The main outcome indexes included the oxygenation index of obese patients before anesthesia induction （T0）， after preoxygenation （T1）， and before PACU entry （T2）. The secondary outcome indexes included the number of cases of attasis at each time point of T0， T1， and T2. The time of SpO2 decreasing to 92% （time interval between SpO2 decreasing to 92% and the start of intubation）， the time of SpO2 restoring to 100% after ventilator connection， intubation time and operation time were recorded. The incidence of postoperative pulmonary complications and the length of hospital stay were compared among different groups. Results Compared with group H， oxygenation indexes at T1 were lower in groups M and L （both P < 0.05）. At T1 and T2， the incidence of atelectasis in groups M and L was significantly lower than that in group H （both P < 0.05）. Among the three groups， the time of SpO2 declining to 92% in group H was （197±57） s，（157±31） s in group M， and （131±23） s in group L， respectively. Compared with group H， the time of SpO2 declining to 92% in groups M and L was significantly shortened （both P < 0.05）. The time of SpO2 restoring to 97% in group H was shorter than that in groups M and L （both P < 0.05）. No significant differences were observed in the incidence of postoperative pulmonary complications and the length of hospital stay among three groups （all P > 0.05）. Conclusions During general anesthesia induction in obese patients， the oxygenation index at 100% oxygen concentration is higher than those at 80% and 60% oxygen concentrations， which is conducive to the restoration of SpO2 after oxygen administration. The incidence of postoperative pulmonary complications and the length of hospital stay do not significantly differ among three groups.

Objective: This study aimed to evaluate the association between the concentration and duration of oxygen therapy and the development and severity of retinopathy of prematurity (ROP). Additionally, it sought to examine the incidence of ROP at Naresuan University Hospital. Materials and Methods: A retrospective observational cohort study was conducted, utilizing data from the medical records of infants admitted to the Neonatal Intensive Care Unit at Naresuan University Hospital, Phitsanulok, Thailand, from January 1, 2016, to December 31, 2022. The duration of various oxygen therapies was recorded in hours, and the concentration of oxygen administered per hour was calculated as the average fraction of inspired oxygen for each infant. These data were subsequently analyzed using STATA version 11.0. Results: Out of 100 eligible infants, 27 (27%) were diagnosed with ROP at different severity levels: 17 infants (62.96%) with ROP stage 1, 9 infants (33.33%) with stage 2, and 1 infant (3.70%) with stage 3. There were no cases of Stage 4 or 5 ROP. The adjusted risk ratio revealed that infants receiving an average FiO2 of 0.3 or higher had a 1.64 times greater risk of developing ROP [95%CI 1.03-2.62], (P-value=0.038). Further analysis using mean difference regression showed a significant correlation between the duration of oxygen therapy and the severity of ROP. Conclusion: This study suggests that regulating oxygen therapy to not exceed an FiO2 of 0.3 and administering it strictly as needed may mitigate the risk of developing ROP and its severe manifestations.

From 1995 to the present, the level of the Caspian Sea decreased by almost 3 m, which significantly affects the morphometry and the ecological state of shallow water areas. First of all, this concerns the shallow Northern Caspian and, especially, the Volga Delta, which over the years has moved 10–20 km forward and grown by about 3000 km2 in area. Changes in the morphometric characteristics of the Volga Delta inevitably affect the hydrodynamic, hydrophysical, hydrochemical, and hydrobiological characteristics of river water in the foredelta. From May 18 to 20, 2021, complex hydrophysical, hydrochemical, and hydrobiological studies of river water were carried out in the southwestern part of the Volga Delta. A total of 32 stations were completed, at which water surface temperature, electrical conductivity, turbidity, and chlorophyll a and oxygen concentrations were measured and samples were taken for further analysis in the laboratory. They showed a complex picture of the distribution of the studied parameters, both along the watercourses and across them. Only high spatial resolution optical and infrared Landsat-8 OLI/TIRS satellite images, obtained on May 20, 2021, almost simultaneously with the ongoing studies in the Volga Delta, helped the spatial distribution of these parameters to be understood. As a result of the analysis of the images, it was possible for the first time to identify a horizontal fine structure of watercourses, which is an alternation of clear immiscible narrow jets with significantly different characteristics of temperature, suspended matter, turbidity, and chlorophyll a. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to compare embryo development, cumulative live birth rate (CLBR), and perinatal outcomes of embryos cultured in 20% and 5% oxygen from days 1 to 3 after insemination. Methods: This retrospective study included patients who received in vitro fertilization (IVF) treatment between January 2015 and November 2019. Embryos of each patient were cultured at 20% or 5% oxygen from days 1–3 after insemination. The primary outcome was CLBR. Propensity score matching (PSM) was used to balance patients' baseline data in both oxygen groups. Results: In total, 31,566 patients were enrolled. After PSM, the rate of high-quality day 3 embryos was significantly lower in the 20% than in the 5% oxygen group (0.49 ± 0.33 vs 0.51 ± 0.33; adjusted β = −0.03; 95% confidence interval [CI], −0.03 to −0.02). The CLBR was significantly lower in the 20% than in the 5% oxygen group (58.6% vs. 62.4%; adjusted odds ratio = 0.85; 95% CI, 0.81–0.90). The birthweight and Z score of singletons were significantly higher in the 20% than in the 5% oxygen group (birthweight: 3.30 ± 0.50 vs. 3.28 ± 0.48; adjusted β = 0.022; 95% CI, 0.004–0.040; Z score: 0.26 ± 1.04 vs. 0.22 ± 1.01; adjusted β = 0.037; 95% CI, 0.001–0.074). Conclusion: Culturing embryos at atmospheric oxygen concentrations from days 1 to 3 compromises embryo quality, reduces CLBR, and affects birthweight. The 5% oxygen concentration is more suitable for embryo culture in IVF laboratories to achieve successful outcomes. [ABSTRACT FROM AUTHOR]

Physisporinus, a genus in Polyporales, Basidiomycota, is a versatile fungus that lives as a wood decomposer, a potential pathogen of standing trees, and an orchid mycobiont. We previously reported that some Physisporinus species inhabiting wet wood in aquatic environments such as streams and waterfalls form synnema-like structures (SSs) bearing acanthophyses at their apices, and that they produce acanthophyses on vegetative hyphae when cultured on agar media. In this study, we investigated the acanthophysis-forming ability in Physisporinus and allied genera, and experimentally demonstrated the function of SSs. Phylogenetic analyses and observations of Meripilus, Physisporinus and Rigidoporus cultures showed that all of the strains forming acanthophyses belonged to Physisporinus, whereas strains of Meripilus and Rigidoporus did not produce acanthophyses. These findings suggest that SS/acanthophysis formation is a useful taxonomic character for members of Physisporinus. When Physisporinus strains were cultured under oxygen (O2) concentrations of 5, 10, 20 and 40%, most of those cultured under 20% O2 formed the most acanthophyses. According to these experimental data, the SSs/acanthophyses in Physisporinus were considered to have a respiratory function. Physisporinus probably acquired the SS/acanthophysis- forming ability to adapt to moist and/or aquatic habitats and to decay wet wood in which the O2 concentration is often low. [ABSTRACT FROM AUTHOR]

The key to upgrade the efficiency of aerobic remediation of landfills is to determine the distribution characteristics of oxygen concentration during aerobic ventilation. This study discusses the distribution law of oxygen concentration with time and radial distance based on a single-well aeration test at an old landfill site. The transient analytical solution of the radial oxygen concentration distribution was deduced using the gas continuity equation and approximation of calculus and logarithmic functions. Oxygen concentration data from the field monitoring were compared with the results predicted by the analytical solution. The results indicated that the oxygen concentration initially increased and then decreased with prolonged aeration time. With an increase in radial distance, the oxygen concentration rapidly declined, followed by a gradual decrease. The influence radius of the aeration well increased slightly when the aeration pressure increased from 2 to 20 kPa. The field test data agreed with the analytical solution prediction results, preliminarily verifying the reliability of the oxygen concentration prediction model. Results from this study provide a basis of guidelines for the design, operation and maintenance management of a landfill aerobic restoration project. [ABSTRACT FROM AUTHOR]

PVC plastic products are common combustible substances seen in fires, but their thermal degradation behavior under different oxygen concentrations has not been adequately studied. The thermal degradation behavior of PVC materials in atmospheres with different oxygen concentrations was analyzed via thermogravimetric–Fourier transform infrared spectroscopy (TG-FTIR). The TG results show that the thermal degradation process of PVC under a non-oxygenated atmosphere occurred in two stages, and the activation energies of the two stages were 130–175 KJ mol−1 and 230–320 KJ mol−1, respectively; under the oxygenated atmosphere, the thermal degradation process occurred in three stages. The activation energies of the three stages were 130–175 KJ mol−1, 145–510 KJ mol−1 and 75–190 KJ mol−1, respectively. And the reaction mechanism of the second stage of thermal degradation was changed from D-ZLT3 to En by the higher oxygen concentration. Infrared spectroscopy (FTIR) was used to analyze the pyrolysis process of PVC in the non-oxygenated atmosphere, and the eight major components were as follows, in descending order according to amount released: C-H stretching > HCl > C-Cl stretching > H2O > CO2 > C-H bending > C-H aliphatic bending > CH2. For the reaction of PVC at an oxygen concentration of 7%, the nine major components, in descending order according to amount released, were as follows: CO2 > HCl > H2O > CO > C-H stretching > C-Cl stretching > C-H aliphatic bending > C-H bending > CH2. For PVC reactions at oxygen concentrations of 14% and 21%, the five major components, in descending order according to amount released, were CO2 > HCl > CO > C-Cl stretching > H2O. [ABSTRACT FROM AUTHOR]

Ahmed Ali Dawud, Ahmed Mohammed Abagaro School of Biomedical Engineering, Jimma Institute of Technology, Jimma University, Jimma, EthiopiaCorrespondence: Ahmed Ali Dawud, Tel +251920846652, Email ahme8002@gmail.comIntroduction: More than 60% of preterm births take place in South Asia and sub-Saharan Africa, making prematurity a primary cause of neonatal mortality. Even though continuous positive airway pressure (CPAP) is a popular treatment for respiratory distress syndrome (RDS) and is safe, practicable, and efficient for use in LMICs, it is crucial to ensure that neonates receive the full benefits of the therapy by monitoring their blood oxygen level.Methods: A centrifugal fan, power source, control system, and sensors are all included in our design. A centrifugal fan was created to provide air at positive pressure in the range of approximately 4 cmH2O to 20 cmH2O utilizing revolving blades (impeller), a DC motor, and a fixed component. The control unit contains a microcontroller to handle sensor data. The proportional-integral (PI) controller board’s external potentiometer is used to set the pressure level.Results: To ascertain whether the prototype satisfies the design requirements, it was constructed and put through several iterations and testing. The proposed device’s prototype was tested for accuracy, affordability, and usability. The centrifugal fan speed measurement was accurate to within 94.5%, while the oxygen concentration sensor reading was accurate to within 98.5%.Conclusion: The design investigates viability of a straightforward, inexpensive, portable SpO2 integrated neonatal CPAP device for use in the delivery room in low-resource countries and to evaluates methods for measuring flows during CPAP treatment by monitoring the level of oxygen in the blood and pressure level delivered by the device using the lowest and safest setting that yields useful results.Graphical Abstract: Keywords: centrifugal fan, CPAP, hypoxemia, oxygen concentration, prematurity, respiratory distress syndrome